Multifunctional fusion protein

Abstract

The invention provides a monoclonal antibody targeting human HHLA2 and a multifunctional fusion antibody molecule derived from the monoclonal antibody, and relates to the field of biological medicine. The HHLA2 monoclonal antibody can be combined with an HHLA2 antigen with high specificity and effectively block an immunosuppression signal channel between the HHLA2 antigen and a receptor KIR3DL3, so that T cell function inhibition is relieved, and the tumor killing function of NK cells is promoted. Based on the antibody skeleton, a fusion antibody containing a plurality of immunomodulatory domains is constructed, and the domains include but are not limited to an anti-PD-L1 antibody or anti-PD-1 antibody or anti-CD3 antibody domain, a CD86 / CD80 variant polypeptide and an LAG3 variant polypeptide. The fusion antibody can cooperatively block a plurality of immune checkpoint pathways, activate a costimulatory signal, promote antigen presenting cell maturation, and enhance T cell activation and killing functions. The provided antibody molecule can be used for preparing immunotherapy drugs for various indications, is especially suitable for treating solid tumors or hematoma, and has remarkable application potential in the aspect of enhancing anti-tumor immune response.

Description

A multifunctional fusion protein TECHNICAL FIELD

[0001] The present application relates to the field of biological medicine, in particular to a fusion polypeptide and use thereof. BACKGROUND

[0002] Immune checkpoint blockade therapy has become a highly potential anti-cancer therapy in the past decade. Since the immune therapy targeting PD-1, PD-L1 and CTLA-4, members of the B7:CD28 pathway, has achieved remarkable clinical efficacy, other members of the B7 family and their receptors have been considered as potential immune regulatory molecules and attracted extensive attention.

[0003] HHLA2 is a newly discovered member of the B7 family, which was originally named B7-H5. However, in recent years, B7-H5 is generally considered as VISTA of the B7 family, and HHLA2 is renamed as B7-H7 or B7y in subsequent studies.

[0004] HHLA2 is a relatively unique member of the B7 family. It is a type I transmembrane protein with low amino acid sequence homology (10-18%) to other B7 family members. Other proteins of the B7 family either contain only one IgV and one IgC domain (B7-1, B7-2, ICOS-L, PD-L1, PD-L2, B7x) or contain two IgV and two IgC domains (B7-H3), different from other members, HHLA2 has three immunoglobulin domains (IgV1, IgC and IgV2).

[0005] Another point different from other proteins in the family is that the sequence of HHLA2 is conserved in evolution in primates, fish, frogs and some mammals (such as giant pandas and naked mice), but not in rodents, so HHLA2 protein is not expressed in rodents, which greatly hinders further animal studies related to HHLA2.

[0006] In normal human physiology, HHLA2 protein expression is only in placental trophoblasts, intestinal, kidney, gallbladder and breast epithelial cells, monocytes and a little HHLA2 protein expression in induced B cells. (Janakiram et al., 2015; Zhao et al., 2013) Compared with normal tissues, HHLA2 protein expression is abnormally high in various cancer tissues, commonly found in lung cancer, breast cancer, ovarian cancer, pancreatic cancer, thyroid cancer, bladder cancer, esophageal cancer, prostate cancer, kidney cancer, testicular cancer, liver cancer, gastric cancer and melanoma. Especially in pancreatic cancer, colon cancer, bladder cancer, triple-negative breast cancer, liver cancer, lung cancer, the expression abundance of HHLA2 is negatively correlated with the prognosis and survival rate of patients. Mechanically, HHLA2 has two ligands, TMIGD2 and KIR3DL3. These two ligands are mainly expressed on T cells and NK cells. Studies have found that the combination of HHLA2 and KIR3DL3 can inhibit the function of T cells and NK cells. Therefore, HHLA2 can play the role of immune checkpoint in vivo, and the combination of HHLA2 and inhibitory ligand inhibits the immune response in vivo. By preparing antibodies to block the signal pathway of HHLA2 and KIR3DL3, the immune system can be reactivated. Moreover, tumor tissues with high expression of HHLA2 often do not express or lowly express PD-L1, which makes HHLA2 another high-potential immune checkpoint independent of the PD-L1 target. The current research on HHLA2 is still in the clinical development stage. From its preclinical data, HHLA2 mAb shows anti-tumor effects, but has the defects of high dosage and general tumor suppression effect. Therefore, antibodies targeting HHLA2 can be used as TAA targeting tumor cells in addition to blocking the HHLA2-KIR3DL3 inhibitory pathway, and can be assembled into multifunctional antibodies with other components such as T cell engager or T cell activation enhancer to enhance the immune response of the body, providing a promising and potential method for treating HHLA2 high expression tumors through immunotherapy.

[0007] LAG3 is a type I transmembrane protein in the immune checkpoint, mainly expressed on activated NK cells and T cells, and LAG3 is expressed on tumor-exhausted CD8 +LAG3 is an effective target for tumor immunotherapy on T cells; but its function has a dual nature, on the one hand, LAG3 plays a negative regulatory role in T cell proliferation and activation, and after LAG3 binds to its ligand MHCII or ligand FGL1, it is involved in the inhibition of T cell activation and function; on the other hand, soluble LAG3 polypeptide is involved in the induction of antigen presenting cell activation, such as up-regulating the expression of CD83 / CD40 / CD80 / CD86, expressing IL-12, TNF-α and other effector cytokines, secreting CCL4, CCL2 and CCL5 and other chemokines to recruit T cells and other effects to participate in the activation of T cells. The antibody antagonizing LAG3 has the effect of directly relieving LAG3-mediated T cell inhibition, but at the same time it also blocks LAG3-mediated activation of antigen presenting cells, so it cannot achieve overall enhancement of LAG3-related immune activation effects, and LAG3 polypeptide has the effect of activating antigen presenting cells, so it has potential prospects for treatment in the fields of tumors, infections and the like. In combination with products related to the HHLA2 target, it has the function of simultaneously activating antigen presenting cells, T cells and NK cells, and plays a better immune regulation role.

[0008] CD86 protein is a kind of immune-related molecule with immune reaction, which realizes its function mainly by regulating T cell immune response, including participating in immune defense, immune tolerance and immune tissue damage, etc. CD86 mainly plays an immune regulatory role by combining with its ligand CD28 and CTLA4 to regulate immune response, and changing the affinity of CD86 and ligand can regulate the related functions mediated by CD86, especially enhancing the immune response function of the body to strengthen the control effect on diseases including tumors, infections, etc. The mature CD86 molecule is composed of extracellular domain (ECD), transmembrane domain and intracellular domain, wherein the extracellular domain (ECD) is the key region of these molecules to combine with the corresponding receptors on T cells. The extracellular domain of CD86 contains immunoglobulin variable-like V (IgV) region and immunoglobulin constant-like C2 (IgC2) region, and the IgV domain is the key domain directly involved in the binding of its receptor. The IgV domain of CD86 can combine with CD28 to participate in inducing T cell activation, proliferation and effector function. CTLA4 can also combine with the IgV region of CD86 to participate in immune suppression regulation. In the regulation of immune response, the activation of T cells is regulated by the combination of costimulatory signal receptors such as CD28 and the corresponding ligand CD86 on the surface of APC, but in the tumor microenvironment, CD86 is usually not expressed or lowly expressed, thus leading to the failure of T cells to be effectively activated, which is one of the key mechanisms of tumor immune escape. In addition, CTLA4 competes with CD28 to bind CD86, and shows higher affinity characteristics, which leads to the failure of CD28 to effectively receive the immune stimulation signal mediated by CD86, so that T cells cannot be effectively activated or immunosuppressed. Similarly, CD80 (B7-1) and CD86 belong to costimulatory molecules and have similar functions. The IgV domain of CD80 extracellular domain can also combine with CD28 to participate in inducing T cell activation, proliferation and effector function. CTLA4 can also combine with the IgV region of CD80 to participate in immune suppression regulation.

[0009] Therefore, the CD86 mutant polypeptide with improved CD86 ligand binding activity and the HHLA2 targeting antibody are combined in the present application, which can effectively stimulate T cells and enhance immune response, so as to treat or prevent diseases caused by the inhibition of T cell function, such as infections, tumors, etc. It has potential therapeutic significance for tumor patients with high expression of HHLA2. Similarly, the CD80 mutant polypeptide with improved CD80 ligand binding activity and the HHLA2 targeting antibody are combined, which can also effectively stimulate T cells and enhance immune response, so as to benefit potential patients. SUMMARY

[0010] First aspect

[0011] In a first aspect, the present application provides an antibody or antigen-binding fragment thereof capable of binding to HHLA2, which can block the anti-binding of HHLA2 to KIR3DL3.

[0012] In some embodiments, the antibody or antigen-binding fragment has the following CDRs or mutations thereof: LCDR1 selected from SEQ ID NO: 245, 253, 261, LCDR2 selected from SEQ ID NO: 246, 254, LCDR3 selected from SEQ ID NO: 247, 255, 271, HCDR1 selected from SEQ ID NO: 242, 250, 258, 266, 273, 277, HCDR2 selected from SEQ ID NO: 243, 251, 259, 267, 274, 278, and HCDR3 selected from SEQ ID NO: 244, 252, 260, 268, 275, 279, 296, wherein the mutations are insertions, deletions or substitutions of 3, 2 or 1 amino acids in the amino acid sequence of the CDRs.

[0013] In some embodiments, the HCDR1, HCDR2, HCDR3 respectively comprise the amino acid sequence selected from SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244; or the HCDR1, HCDR2, HCDR3 respectively comprise the amino acid sequence selected from SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252; or the HCDR1, HCDR2, HCDR3 respectively comprise the amino acid sequence selected from SEQ ID NO: 258, SEQ ID NO: 259, SEQ ID NO: 260; or the HCDR1, HCDR2, HCDR3 respectively comprise the amino acid sequence selected from SEQ ID NO: 266, SEQ ID NO: 267, SEQ ID NO: 268; or the HCDR1, HCDR2, HCDR3 respectively comprise the amino acid sequence selected from SEQ ID NO: 273, SEQ ID NO: 274, SEQ ID NO: 275; or the HCDR1, HCDR2, HCDR3 respectively comprise the amino acid sequence selected from SEQ ID NO: 273, SEQ ID NO: 274, SEQ ID NO: 296; or the HCDR1, HCDR2, HCDR3 respectively comprise the amino acid sequence selected from SEQ ID NO: 277, SEQ ID NO: 278, SEQ ID NO: 279.

[0014] In some embodiments, the LCDR1, LCDR2, LCDR3, respectively, comprise an amino acid sequence selected from the group consisting of SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 247; or the LCDR1, LCDR2, LCDR3, respectively, comprise an amino acid sequence selected from the group consisting of SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255; or the LCDR1, LCDR2, LCDR3, respectively, comprise an amino acid sequence selected from the group consisting of SEQ ID NO: 261, SEQ ID NO: 254, SEQ ID NO: 255; or the LCDR1, LCDR2, LCDR3, respectively, comprise an amino acid sequence selected from the group consisting of SEQ ID NO: 261, SEQ ID NO: 254, SEQ ID NO: 271.

[0015] In some embodiments, the HCDR1, HCDR2, HCDR3, respectively, comprise an amino acid sequence selected from the group consisting of SEQ ID NO: 242, SEQ ID NO: 243, SEQ ID NO: 244, and the LCDR1, LCDR2, LCDR3, respectively, comprise an amino acid sequence selected from the group consisting of SEQ ID NO: 245, SEQ ID NO: 246, SEQ ID NO: 247; or the HCDR1, HCDR2, HCDR3, respectively, comprise an amino acid sequence selected from the group consisting of SEQ ID NO: 250, SEQ ID NO: 251, SEQ ID NO: 252, and the LCDR1, LCDR2, LCDR3, respectively, comprise an amino acid sequence selected from the group consisting of SEQ ID NO: 253, SEQ ID NO: 254, SEQ ID NO: 255; or the HCDR1, HCDR2, HCDR3, respectively, comprise an amino acid sequence selected from the group consisting of SEQ ID NO: 258, SEQ ID NO: 259, SEQ ID NO: 260, and the LCDR1, LCDR2, LCDR3, respectively, comprise an amino acid sequence selected from the group consisting of SEQ ID NO: 261, SEQ ID NO: 254, SEQ ID NO: 255; or the HCDR1, HCDR2, HCDR3, respectively, comprise an amino acid sequence selected from the group consisting of SEQ ID NO: 266, SEQ ID NO: 267, SEQ ID NO: 268, and the LCDR1, LCDR2, LCDR3, respectively, comprise an amino acid sequence selected from the group consisting of SEQ ID NO: 261, SEQ ID NO: 254, SEQ ID NO: 271.

[0016] In some embodiments, the antibody or antigen-binding fragment further comprises humanization modifications of a heavy chain variable region framework region (VH FWR) and / or a light chain variable region framework region (VL FWR), wherein the VH FWR comprises a VH FWR1, a VH FWR2, a VH FWR3, and a VH FWR4, and the VL FWR comprises a VL FWR1, a VL FWR2, a VL FWR3, and a VL FWR4.

[0017] In some embodiments, the VH FWR is derived from a human antibody heavy chain variable region framework region, and the encoding gene is preferably derived from germline V genes IGHV1-46*01, IGHV1-2*02, IGHV1-3*01; and / or the VL FWR is derived from a human antibody light chain variable region framework region, and the encoding gene is preferably derived from germline V genes IGKV1-NL1*01, IGKV1-5*01, IGKV3-20*01.

[0018] In some embodiments, the VH FWR1 comprises the amino acid sequence set forth in SEQ ID NO: 298; and / or the VH FWR2 comprises the amino acid sequence set forth in SEQ ID NO: 299; and / or the VH FWR3 comprises the amino acid sequence set forth in SEQ ID NO: 300, 310, 320, 340; the VH FWR4 comprises the amino acid sequence set forth in SEQ ID NO: 301; the VL FWR1 comprises the amino acid sequence set forth in SEQ ID NO: 303, 323; and / or the VL FWR2 comprises the amino acid sequence set forth in SEQ ID NO: 304, 324; and / or the VL FWR3 comprises the amino acid sequence set forth in SEQ ID NO: 305, 325, 335; and / or the VL FWR4 comprises the amino acid sequence set forth in SEQ ID NO: 306.

[0019] In some embodiments, the VH FWR1, VH FWR2, VH FWR3, and VH FWR4 comprise the amino acid sequences set forth in SEQ ID NO: 298, SEQ ID NO: 299, SEQ ID NO: 300, SEQ ID NO: 301, respectively; or the VH FWR1, VH FWR2, VH FWR3, and VH FWR4 comprise the amino acid sequences set forth in SEQ ID NO: 298, SEQ ID NO: 299, SEQ ID NO: 310, SEQ ID NO: 301, respectively; or the VH FWR1, VH FWR2, VH FWR3, and VH FWR4 comprise the amino acid sequences set forth in SEQ ID NO: 298, SEQ ID NO: 299, SEQ ID NO: 320, SEQ ID NO: 301, respectively; or the VH FWR1, VH FWR2, VH FWR3, and VH FWR4 comprise the amino acid sequences set forth in SEQ ID NO: 298, SEQ ID NO: 299, SEQ ID NO: 340, SEQ ID NO: 301, respectively.

[0020] In some embodiments, the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 comprise the amino acid sequences set forth in SEQ ID NO: 303, SEQ ID NO: 304, SEQ ID NO: 305, SEQ ID NO: 306, respectively; or the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 comprise the amino acid sequences set forth in SEQ ID NO: 323, SEQ ID NO: 324, SEQ ID NO: 325, SEQ ID NO: 306, respectively; or the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 comprise the amino acid sequences set forth in SEQ ID NO: 323, SEQ ID NO: 324, SEQ ID NO: 335, SEQ ID NO: 306, respectively.

[0021] In some embodiments, the VH FWR1, VH FWR2, VH FWR3, and VH FWR4 comprise the amino acid sequences set forth in SEQ ID NO: 298, SEQ ID NO: 299, SEQ ID NO: 300, SEQ ID NO: 301, respectively, and the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 comprise the amino acid sequences set forth in SEQ ID NO: 303, SEQ ID NO: 304, SEQ ID NO: 305, SEQ ID NO: 306, respectively; or the VH FWR1, VH FWR2, VH FWR3, and VH FWR4 comprise the amino acid sequences set forth in SEQ ID NO: 298, SEQ ID NO: 299, SEQ ID NO: 310, SEQ ID NO: 301, respectively, and the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 comprise the amino acid sequences set forth in SEQ ID NO: 303, SEQ ID NO: 304, SEQ ID NO: 305, SEQ ID NO: 306, respectively; or the VH FWR1, VH FWR2, VH FWR3, and VH FWR4 comprise the amino acid sequences set forth in SEQ ID NO: 298, SEQ ID NO: 299, SEQ ID NO: 320, SEQ ID NO: 301, respectively, and the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 comprise the amino acid sequences set forth in SEQ ID NO: 323, SEQ ID NO: 324, SEQ ID NO: 325, SEQ ID NO: 306, respectively; or the VH FWR1, VH FWR2, VH FWR3, and VH FWR4 comprise the amino acid sequences set forth in SEQ ID NO: 298, SEQ ID NO: 299, SEQ ID NO: 320, SEQ ID NO: 301, respectively, and the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 comprise the amino acid sequences set forth in SEQ ID NO: 323, SEQ ID NO: 324, SEQ ID NO: 335, SEQ ID NO: 306, respectively.VH FWR1, VH FWR2, VH FWR3, and VH FWR4 comprise the amino acid sequences set forth in SEQ ID NO:298, SEQ ID NO:299, SEQ ID NO:300, SEQ ID NO:301, respectively, and the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 comprise the amino acid sequences set forth in SEQ ID NO:323, SEQ ID NO:324, SEQ ID NO:325, SEQ ID NO:306, respectively; or the VH FWR1, VH FWR2, VH FWR3, and VH FWR4 comprise the amino acid sequences set forth in SEQ ID NO:298, SEQ ID NO:299, SEQ ID NO:300, SEQ ID NO:301, respectively, and the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 comprise the amino acid sequences set forth in SEQ ID NO:323, SEQ ID NO:324, SEQ ID NO:335, SEQ ID NO:306, respectively; or the VH FWR1, VH FWR2, VH FWR3, and VH FWR4 comprise the amino acid sequences set forth in SEQ ID NO:298, SEQ ID NO:299, SEQ ID NO:340, SEQ ID NO:301, respectively, and the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 comprise the amino acid sequences set forth in SEQ ID NO:323, SEQ ID NO:324, SEQ ID NO:335, SEQ ID NO:306, respectively.

[0022] In some embodiments, the VH comprises an amino acid sequence as set forth in any one of SEQ ID NO:280, SEQ ID NO:282, SEQ ID NO:284, SEQ ID NO:286, SEQ ID NO:288, SEQ ID NO:290, SEQ ID NO:292, SEQ ID NO:293, SEQ ID NO:295, SEQ ID NO:297, SEQ ID NO:307, SEQ ID NO:317, SEQ ID NO:337, SEQ ID NO:357.

[0023] In some embodiments, the VL comprises an amino acid sequence as set forth in any one of SEQ ID NO: 281, SEQ ID NO: 283, SEQ ID NO: 285, SEQ ID NO: 287, SEQ ID NO: 289, SEQ ID NO: 291, SEQ ID NO: 302, SEQ ID NO: 322, SEQ ID NO: 32.

[0024] In some embodiments, the VH comprises an amino acid sequence as set forth in SEQ ID NO: 284 and the VL comprises an amino acid sequence as set forth in SEQ ID NO: 285; or the VH comprises an amino acid sequence as set forth in SEQ ID NO: 286 and the VL comprises an amino acid sequence as set forth in SEQ ID NO: 287; or the VH comprises an amino acid sequence as set forth in SEQ ID NO: 288 and the VL comprises an amino acid sequence as set forth in SEQ ID NO: 289; or the VH comprises an amino acid sequence as set forth in SEQ ID NO: 290 and the VL comprises an amino acid sequence as set forth in SEQ ID NO: 291; or the VH comprises an amino acid sequence as set forth in SEQ ID NO: 297 and the VL comprises an amino acid sequence as set forth in SEQ ID NO: 302; or the VH comprises an amino acid sequence as set forth in SEQ ID NO: 307 and the VL comprises an amino acid sequence as set forth in SEQ ID NO: 302; or the VH comprises an amino acid sequence as set forth in SEQ ID NO: 317 and the VL comprises an amino acid sequence as set forth in SEQ ID NO: 322; or the VH comprises an amino acid sequence as set forth in SEQ ID NO: 317 and the VL comprises an amino acid sequence as set forth in SEQ ID NO: 332; or the VH comprises an amino acid sequence as set forth in SEQ ID NO: 337 and the VL comprises an amino acid sequence as set forth in SEQ ID NO: 322; or the VH comprises an amino acid sequence as set forth in SEQ ID NO: 357 and the VL comprises an amino acid sequence as set forth in SEQ ID NO: 322; or the VH comprises an amino acid sequence as set forth in SEQ ID NO: 337 and the VL comprises an amino acid sequence as set forth in SEQ ID NO: 332.

[0025] In some embodiments, the antibody heavy chain comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272, SEQ ID NO: 276, SEQ ID NO: 367, SEQ ID NO: 368, SEQ ID NO: 369, SEQ ID NO: 370, SEQ ID NO: 371, SEQ ID NO: 372.

[0026] In some embodiments, the antibody light chain comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257, SEQ ID NO: 265, SEQ ID NO: 373, SEQ ID NO: 374, SEQ ID NO: 375.

[0027] In some embodiments, the antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 240, and the light chain comprises an amino acid sequence as set forth in SEQ ID NO: 241; or the antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 248, and the light chain comprises an amino acid sequence as set forth in SEQ ID NO: 249; or the antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 256, and the light chain comprises an amino acid sequence as set forth in SEQ ID NO: 257; or the antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 264, and the light chain comprises an amino acid sequence as set forth in SEQ ID NO: 265; or the antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 368, and the light chain comprises an amino acid sequence as set forth in SEQ ID NO: 373; or the antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 369, and the light chain comprises an amino acid sequence as set forth in SEQ ID NO: 373; or the antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 370, and the light chain comprises an amino acid sequence as set forth in SEQ ID NO: 374; or the antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 370, and the light chain comprises an amino acid sequence as set forth in SEQ ID NO: 375; or the antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 371, and the light chain comprises an amino acid sequence as set forth in SEQ ID NO: 374; or the antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 372, and the light chain comprises an amino acid sequence as set forth in SEQ ID NO: 375; or the antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 371, and the light chain comprises an amino acid sequence as set forth in SEQ ID NO: 375.

[0028] In some embodiments, the antibody or antigen-binding fragment can be a recombinant antibody, a single domain antibody, a heavy chain antibody, a chimeric antibody, and a bispecific antibody, or a monoclonal antibody or a polyclonal antibody prepared from the above-mentioned antibodies.

[0029] In some embodiments, the antibody or antigen-binding fragment can be a Fab, a Fab', a Fv fragment, a F(ab')2, a F(ab)2, a scFv, a di-scFv, a VHH, or a dAb.

[0030] Second aspect

[0031] In a second aspect, the present application provides a fusion polypeptide comprising a first domain and a second domain, wherein the first domain is capable of blocking HHLA2 / KIR3DL3 signaling, and the second domain is capable of binding CD28 and / or CTLA4.

[0032] In some embodiments, the first domain of the fusion polypeptide is capable of binding HHLA2.

[0033] In some embodiments, the first domain of the fusion polypeptide is an antibody or an antigen-binding fragment thereof.

[0034] In some embodiments, the first domain of the fusion polypeptide is as described in the first aspect of the present application.

[0035] In some embodiments, the first domain of the fusion polypeptide comprises a complementarity determining region or a variable region selected from RP004263 (derived from patent WO2023138579A1) or hz2D7 (derived from patent WO2020041300A1).

[0036] In some embodiments, the second domain of the fusion polypeptide comprises CD86 or CD80 or a functionally active fragment thereof, or / and a variant of CD86 or CD80.

[0037] In some embodiments, the second domain of the fusion polypeptide is of human or murine origin.

[0038] In some embodiments, the second domain of the fusion polypeptide comprises an IgV domain of CD86 or CD80 or a functionally active fragment thereof.

[0039] In some embodiments, the second domain of the fusion polypeptide comprises an extracellular domain of CD86 or CD80 or a functionally active fragment thereof.

[0040] In some embodiments, the second domain of the fusion polypeptide comprises a CD86 variant polypeptide, which comprises an amino acid substitution mutation of humanized CD86.

[0041] In some embodiments, the second domain of the fusion polypeptide comprises a CD86 variant polypeptide, which comprises an IgV domain amino acid substitution mutant of CD86 and / or an extracellular domain amino acid substitution mutant of humanized CD86.

[0042] In some embodiments, the CD86 variant polypeptide of the fusion polypeptide comprises an IgV domain amino acid substitution mutant of CD86, the mutation site of which comprises one or more of the amino acid site mutations selected from the group consisting of: A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

[0043] In some embodiments, the CD86 variant polypeptide of the fusion polypeptide comprises an IgV domain amino acid substitution mutant of CD86, the amino acid substitution mutant of which comprises a combination selected from the group consisting of: Q25I / F33L / H90I, Q25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V, Q25V / F33L / H90V, Q25I / F33V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F33L / H90I, A13L / Q25V / F33L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M60R / H90I, Q25V / F33L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F, Q25I / F33A / H90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13F / Q25I / F33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I, and Q25I / F33L / H90M.

[0044] In some embodiments, the CD86 variant polypeptide of the fusion polypeptide comprises an IgV domain amino acid substitution mutant of CD86, the amino acid substitution mutant of which comprises a combination selected from the group consisting of: Q25I / F33L / H90I.

[0045] In some embodiments, the CD86 variant polypeptide of the fusion polypeptide comprises an extracellular domain amino acid substitution mutant of CD86 comprising one or more of the amino acid site mutations selected from the group of A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

[0046] In some embodiments, the CD86 variant polypeptide of the fusion polypeptide comprises an extracellular domain amino acid substitution mutant of CD86 comprising a combination of Q25I / F33L / H90I, Q25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V, Q25V / F33L / H90V, Q25I / F33V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F33L / H90I, A13L / Q25V / F33L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M60R / H90I, Q25V / F33L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F, Q25I / F33A / H90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13F / Q25I / F33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I, and Q25I / F33L / H90M; preferably, the CD86 variant polypeptide of the fusion polypeptide comprises an extracellular domain amino acid substitution mutant of CD86 comprising a combination of Q25I / F33L / H90I.

[0047] In some embodiments, the second domain is selected from the group consisting of the amino acid sequences of SEQ ID NO: 2 to SEQ ID NO: 3, SEQ ID NO: 22 to SEQ ID NO: 87.

[0048] In some embodiments, the second domain of the fusion polypeptide comprises a CD80 variant polypeptide comprising an amino acid substitution mutation of IgV domain of CD80 and / or an extracellular domain amino acid substitution mutation of humanized CD80.

[0049] In some embodiments, the second domain of the fusion polypeptide comprises a CD80 variant polypeptide comprising an amino acid substitution mutation of IgV domain of CD80 and / or an extracellular domain amino acid substitution mutation of humanized CD80.

[0050] In some embodiments, the first domain is directly or indirectly linked to the second domain.

[0051] In some embodiments, the first domain heavy chain is directly or indirectly linked to the second domain; preferably, the C-terminus of the first domain heavy chain is directly or indirectly linked to the N-terminus of the second domain; preferably, the N-terminus of the first domain heavy chain is directly or indirectly linked to the C-terminus of the second domain.

[0052] In some embodiments, the first domain light chain is directly or indirectly linked to the second domain; preferably, the C-terminus of the first domain light chain is directly or indirectly linked to the N-terminus of the second domain; preferably, the N-terminus of the first domain light chain is directly or indirectly linked to the C-terminus of the second domain.

[0053] In some embodiments, the indirect linkage comprises linkage via a linker; preferably, the linker comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 16-21.

[0054] In some embodiments, the fusion polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 400-496, SEQ ID NO: 639.

[0055] In some embodiments, the fusion polypeptide further comprises a third domain capable of activating innate immune response.

[0056] In some embodiments, the third domain is capable of binding to MHCII molecules on antigen presenting cells.

[0057] In some embodiments, the third domain is LAG3 or a functional fragment thereof, or a variant polypeptide thereof.

[0058] In some embodiments, the third domain of LAG3 or a functional fragment thereof is derived from human or from mouse.

[0059] In some embodiments, the third domain comprises an extracellular domain of LAG3 or a functionally active fragment thereof.

[0060] In some embodiments, the third domain comprises IgD1, IgD2, IgD3 and / or IgD4 of LAG3 or a functionally active fragment thereof.

[0061] In some embodiments, the third domain comprises IgD1, IgD1-IgD2, IgD1-IgD2-IgD3, and / or IgD1-IgD2-IgD3-IgD4 of LAG3 or a functionally active fragment thereof.

[0062] In some embodiments, the third domain comprises a LAG3 variant polypeptide comprising a truncation and / or mutation based on human-derived LAG3.

[0063] In some embodiments, the third domain comprises a LAG3 variant polypeptide comprising a truncation based on wild-type human-derived LAG3 extracellular region polypeptide.

[0064] In some embodiments, the LAG3 variant polypeptide comprises an amino acid sequence truncated by 0-124 amino acids or 125-145 amino acids at the N-terminus based on wild-type human-derived LAG3 extracellular region polypeptide.

[0065] In some embodiments, the LAG3 variant polypeptide comprises an amino acid sequence that is 0, 5, 21, 37, 45, 60, 71, 74, 79, 81, 84, 89, 94, 99, 104, 109, or 114 amino acids shorter at the N-terminus than a wild-type human LAG3 extracellular region polypeptide; or, the LAG3 variant polypeptide comprises an amino acid sequence that is 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, or 145 amino acids shorter at the N-terminus than a wild-type human LAG3 extracellular region polypeptide; or, the LAG3 variant polypeptide comprises an amino acid sequence that is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124 amino acids shorter at the N-terminus than a wild-type human LAG3 extracellular region polypeptide.

[0066] In some embodiments, the LAG3 variant polypeptide comprises an amino acid sequence that is 0, 5, 21, 37, 45, 60, 71, 74, 81, or 99 amino acids shorter at the N-terminus than a wild-type human LAG3 extracellular region polypeptide.

[0067] In some embodiments, the LAG3 variant polypeptide comprises an amino acid sequence that is 0, 5, 21, 37, 45, 60, 71, or 74 amino acids shorter at the N-terminus than a wild-type human LAG3 extracellular region polypeptide.

[0068] In some embodiments, the C-terminus of the LAG3 variant polypeptide terminates at a position corresponding to any of amino acid positions 121-167 of a wild-type LAG3 extracellular region polypeptide, a position corresponding to any of amino acid positions 148-167 of a wild-type LAG3 extracellular region polypeptide, or a position corresponding to any of amino acid positions 1-121 of a wild-type LAG3 extracellular region polypeptide.

[0069] In some embodiments, the C-terminus of the LAG3 variant polypeptide terminates at a position corresponding to any of amino acid positions 122-167 of a wild-type LAG3 extracellular region polypeptide.

[0070] In some embodiments, the LAG3 variant polypeptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide that terminates at the C-terminus at amino acid position 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167; or, the LAG3 variant polypeptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide that terminates at the C-terminus at amino acid position 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167; or, the LAG3 variant polypeptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide that terminates at the C-terminus at a position corresponding to amino acid position 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, or 121.

[0071] In some embodiments, the LAG3 variant polypeptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide that terminates at the C-terminus at amino acid position 121, 122, 129, 136, 146, 156, 161, or 167.

[0072] In some embodiments, the LAG3 variant polypeptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide that terminates at the C-terminus at amino acid position 121, 146, 156, 161, or 167.

[0073] In some embodiments, the LAG3 variant polypeptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide that terminates at the C-terminus at amino acid position 156, 161, or 167.

[0074] In some embodiments, the LAG3 variant polypeptide comprises 0, 5, 21, 37, 45, 60, 71, 74, 79, 84, 89, 94, 99, 104, 109, or 114 amino acids truncated from the N-terminus and terminates at the C-terminus with the amino acid sequence of amino acid position 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 of the wild-type human LAG3 extracellular region polypeptide.

[0075] In some embodiments, the LAG3 variant polypeptide comprises 0, 5, 21, 37, 45, 60, 71, 74, 81, or 99 amino acids truncated from the N-terminus and terminates at the C-terminus with the amino acid sequence of amino acid position 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 of the wild-type human LAG3 extracellular region polypeptide.

[0076] In some embodiments, the LAG3 variant polypeptide comprises 0, 5, 21, 37, 45, 60, 71, or 74 amino acids truncated from the N-terminus and terminates at the C-terminus with the amino acid sequence of amino acid position 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 of the wild-type human LAG3 extracellular region polypeptide.

[0077] In some embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation.

[0078] In some embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation, the amino acid mutation site comprises an Arg amino acid at position 97.

[0079] In some embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation, the amino acid mutation site comprises an Arg amino acid at position 97 mutated to a Glu amino acid.

[0080] In some embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation, the amino acid mutation site comprises an Arg amino acid at position 110.

[0081] In some embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation, the R110 site mutation is K110.

[0082] In some embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation, the R113 site mutation is K113.

[0083] In some embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation, the R119 site mutation is K119.

[0084] In some embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation, the R129 site mutation is K129.

[0085] In some embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation, the G130 site mutation is P130, or A130, or T130, or Y130, or S130.

[0086] In some embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation, the R141 site mutation is K141.

[0087] In some embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation, the R141 site mutation is K141 and / or the G130 site mutation is P130.

[0088] In some embodiments, the LAG3 variant polypeptide is truncated by 81 amino acids at the N-terminus and terminates at amino acid position 121 at the C-terminus, and comprises a mutation at the R110, and / or R113, and / or R119 site.

[0089] In some embodiments, the LAG3 variant polypeptide is truncated by 99 amino acids at the N-terminus and terminates at amino acid position 146 at the C-terminus, and comprises a mutation at the R129, and / or G130, and / or R141 site.

[0090] In some embodiments, the LAG3 variant polypeptide is truncated by 81 amino acids at the N-terminus and terminates at amino acid position 146 at the C-terminus, and comprises a mutation at the R110, and / or R113, and / or R119, and / or R129, and / or G130, and / or R141 site.

[0091] In some embodiments, the LAG3 variant polypeptide is truncated by 81 amino acids at the N-terminus and terminates at amino acid position 146 at the C-terminus, and comprises a mutation at the R110, and / or R113, and / or R119, and / or R129, and / or G130, and / or R141 site.

[0092] In some embodiments, the second domain comprises a LAG3 variant polypeptide having at least one feature selected from the group consisting of:

[0093] (1) N-terminally truncated by 74 amino acids and C-terminally truncated at a position corresponding to amino acid position 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 of the wild-type LAG3 ectodomain polypeptide; preferably, C-terminally truncated at a position corresponding to amino acid position 122, 129, 136, 146, 156, 161 of the wild-type LAG3 ectodomain polypeptide;

[0094] (2) N-terminally truncated by 74 amino acids, Arg at position 97 mutated to Glu, and C-terminally truncated at a position corresponding to amino acid position 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 of the wild-type LAG3 ectodomain polypeptide; preferably, C-terminally truncated at a position corresponding to amino acid position 122, 129, 136, 146, 156, 161 of the wild-type LAG3 ectodomain polypeptide;

[0095] (3) N-terminally truncated by 5 amino acids and C-terminally truncated at a position corresponding to amino acid position 156, 161, or 167 of the wild-type LAG3 ectodomain polypeptide;

[0096] (4) N-terminally truncated by 5 amino acids, Arg at position 97 mutated to Glu, and C-terminally truncated at a position corresponding to amino acid position 156, 161, or 167 of the wild-type LAG3 ectodomain polypeptide;

[0097] (5) N-terminally truncated by 21 amino acids and C-terminally truncated at a position corresponding to amino acid position 156, 161, or 167 of the wild-type LAG3 ectodomain polypeptide;

[0098] (6) N-terminally truncated by 21 amino acids, Arg at position 97 mutated to Glu, and C-terminally truncated at a position corresponding to amino acid position 156, 161, or 167 of the wild-type LAG3 ectodomain polypeptide;

[0099] (7) N-terminally truncated by 37 amino acids and C-terminally truncated at a position corresponding to amino acid position 156, 161, or 167 of the wild-type LAG3 ectodomain polypeptide;

[0100] (8) N-terminal truncation of 37 amino acids, mutation of Arg amino acid at position 97 to Glu amino acid, and C-terminal termination at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 extracellular region polypeptide;

[0101] (9) N-terminal truncation of 45 amino acids, and C-terminal termination at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 extracellular region polypeptide;

[0102] (10) N-terminal truncation of 45 amino acids, mutation of Arg amino acid at position 97 to Glu amino acid, and C-terminal termination at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 extracellular region polypeptide;

[0103] (11) N-terminal truncation of 60 amino acids, and C-terminal termination at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 extracellular region polypeptide;

[0104] (12) N-terminal truncation of 60 amino acids, mutation of Arg amino acid at position 97 to Glu amino acid, and C-terminal termination at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 extracellular region polypeptide;

[0105] (13) N-terminal truncation of 71 amino acids, and C-terminal termination at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 extracellular region polypeptide;

[0106] (14) N-terminal truncation of 71 amino acids, mutation of Arg amino acid at position 97 to Glu amino acid, and C-terminal termination at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 extracellular region polypeptide;

[0107] (15) N-terminal truncation of 79 amino acids, and C-terminal termination at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 extracellular region polypeptide;

[0108] (16) N-terminal truncation of 84 amino acids, and C-terminal termination at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 extracellular region polypeptide;

[0109] (17) N-terminal truncation of 89 amino acids, and C-terminal termination at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 extracellular region polypeptide;

[0110] (18) N-terminally truncated by 94 amino acids and C-terminally truncated at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0111] (19) N-terminally truncated by 99 amino acids and C-terminally truncated at a position corresponding to amino acid position 146, 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0112] (20) N-terminally truncated by 99 amino acids and C-terminally truncated at amino acid position 146, and mutated at the R129, and / or G130, and / or R141 site;

[0113] (21) N-terminally truncated by 104 amino acids and C-terminally truncated at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0114] (22) N-terminally truncated by 109 amino acids and C-terminally truncated at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0115] (23) N-terminally truncated by 114 amino acids and C-terminally truncated at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0116] (24) N-terminally truncated by 0 amino acids and C-terminally truncated at a position corresponding to amino acid position 122, 129, 136, 146, 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0117] (25) N-terminally truncated by 0 amino acids, mutated at position 97 from Arg to Glu, and C-terminally truncated at a position corresponding to amino acid position 122, 129, 136, 146, 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0118] (26) N-terminally truncated by 81 amino acids and C-terminally truncated at amino acid position 121, and mutated at the R110, and / or R113, and / or R119 site;

[0119] (27) N-terminally truncated by 81 amino acids and C-terminally truncated at amino acid position 146, and mutated at the R110, and / or R113, and / or R119, and / or R129, and / or G130, and / or R141 site.

[0120] In some embodiments, the third domain comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 5 to SEQ ID NO: 13 and SEQ ID NO: 88 to SEQ ID NO: 227.

[0121] In some embodiments, the first domain is directly or indirectly connected to the third domain.

[0122] In some embodiments, the heavy chain of the first domain is directly or indirectly connected to the third domain.

[0123] In some embodiments, the N-terminus of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0124] In some embodiments, the N-terminus of the heavy chain of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0125] In some embodiments, the N-terminus of the light chain of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0126] In some embodiments, the C-terminus of the first domain is directly or indirectly connected to the N-terminus of the third domain.

[0127] In some embodiments, the C-terminus of the heavy chain of the first domain is directly or indirectly connected to the N-terminus of the third domain.

[0128] In some embodiments, the C-terminus of the light chain of the first domain is directly or indirectly connected to the N-terminus of the third domain.

[0129] In some embodiments, the second domain is directly or indirectly connected to the third domain.

[0130] In some embodiments, the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0131] In some embodiments, the N-terminus of the second domain is directly or indirectly connected to the C-terminus of the third domain.

[0132] In some embodiments, the first domain is directly or indirectly connected to the second domain, and the second domain is directly or indirectly connected to the third domain.

[0133] In some embodiments, the C-terminus of the first domain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0134] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0135] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0136] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0137] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0138] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0139] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0140] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0141] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0142] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0143] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0144] In some embodiments, the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the third domain, and the N-terminus of the third domain is directly or indirectly connected to the C-terminus of the second domain.

[0145] In some embodiments, the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the third domain, and the N-terminus of the third domain is directly or indirectly connected to the C-terminus of the second domain.

[0146] In some embodiments, the first domain is directly or indirectly connected to the second domain, and the first domain is directly or indirectly connected to the third domain.

[0147] In some embodiments, the C-terminus of the first domain is directly or indirectly connected to the N-terminus of the second domain, and the N-terminus of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0148] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the third domain.

[0149] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the third domain.

[0150] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the third domain.

[0151] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the third domain.

[0152] In some embodiments, the N-terminus of the first domain is directly or indirectly connected to the C-terminus of the second domain, and the C-terminus of the first domain is directly or indirectly connected to the N-terminus of the third domain.

[0153] In some embodiments, the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the second domain, and the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the third domain.

[0154] In some embodiments, the N-terminus of the first domain light chain is directly or indirectly connected to the C-terminus of the second domain, and the C-terminus of the first domain light chain is directly or indirectly connected to the N-terminus of the third domain.

[0155] In some embodiments, the N-terminus of the first domain light chain is directly or indirectly connected to the C-terminus of the second domain, and the C-terminus of the first domain light chain is directly or indirectly connected to the N-terminus of the third domain.

[0156] In some embodiments, the N-terminus of the first domain light chain is directly or indirectly connected to the C-terminus of the second domain, and the C-terminus of the first domain light chain is directly or indirectly connected to the N-terminus of the third domain.

[0157] In some embodiments, the indirect connection comprises a connection via a linker; preferably, the linker comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 16-21.

[0158] In some embodiments, the fusion polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 412-441, SEQ ID NOs: 448-488, SEQ ID NOs: 500-519, SEQ ID NOs: 528-582, SEQ ID NO: 774.

[0159] In some embodiments, a fourth domain can also be included, which is capable of binding on T cells and / or NK and / or tumor cells.

[0160] In some embodiments, the fourth domain is capable of blocking PD-L1, PD-1 pathway, or capable of blocking other known immune checkpoint pathways, or capable of binding target on T cells / NK cells to bring T cells / NK cells and tumor cells closer, or capable of binding TAA on other tumor cells.

[0161] In some embodiments, the fourth domain comprises the same or different antibody or antigen binding fragment as the second domain.

[0162] In some embodiments, the fourth domain antigen binding fragment is selected from one or more of the following group: Fab, Fab', Fv fragment, F(ab')2, F(ab)2, scFv, di-scFv, VHH, and dAb.

[0163] In some embodiments, the fourth domain is capable of binding one or more of the target selected from the group of HHLA2, PD-L1, PD-L2, PD-1, OX40, 4-1BB, ICOS, TIGIT, CTLA4, LAG3, CD3, VEGF, VEGFR, CD47, HGF, Trop2, EpCAM, CCR8, CCR4, CCR5, GPRC5D, BCMA, CD19, CD20, HER-2neu, DLL1, HER-3, HER-4, EGFR, PSMA, CEA, MUC-1 (mucin), MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC7, CD123, CD33, CD30, CD38, NKG2A, Nkp36, Tim3, and 5T4.

[0164] In some preferred embodiments, the fourth domain is capable of binding PD-L1 and / or PD-1.

[0165] In some embodiments, the fourth domain comprises an antibody or antigen binding fragment thereof selected from the group of Sugemalimab, Atezolizumab, Permbrolizumab, and Nivolumab.

[0166] In some embodiments, the fourth domain comprises Sugemalimab or an antigen binding fragment thereof, Atezolizumab or an antigen binding fragment thereof, Permbrolizumab or an antigen binding fragment thereof, or Nivolumab or an antigen binding fragment thereof.

[0167] In some embodiments, the fourth domain comprises HCDR1, HCDR2, and / or HCDR3 of a heavy chain of an antibody, the antibody heavy chain comprising an amino acid sequence selected from the group of SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272, and SEQ ID NO: 276.

[0168] In some embodiments, the fourth domain comprises a heavy chain variable region VH of an antibody heavy chain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272, and SEQ ID NO: 276.

[0169] In some embodiments, the fourth domain comprises an antibody heavy chain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272, and SEQ ID NO: 276.

[0170] In some embodiments, the fourth domain comprises a LCDR1, a LCDR2, and / or a LCDR3 of a light chain of an antibody light chain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257, and SEQ ID NO: 265.

[0171] In some embodiments, the fourth domain comprises a light chain variable region VL of an antibody light chain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257, and SEQ ID NO: 265.

[0172] In some embodiments, the fourth domain comprises an antibody light chain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257, and SEQ ID NO: 265.

[0173] In some embodiments, the fourth domain is directly or indirectly connected to the first domain.

[0174] In some embodiments, the heavy chain of the fourth domain is directly or indirectly connected to the heavy chain of the first domain.

[0175] In some embodiments, the heavy chain of the fourth domain is directly or indirectly connected to the heavy chain of the first domain via a disulfide bond or via a complementary stereostructure (knob-into-hole, KiH).

[0176] In some embodiments, the light chain of the fourth domain is directly or indirectly connected to the heavy chain of the first domain.

[0177] In some embodiments, the heavy chain of the fourth domain is directly or indirectly connected to the light chain of the first domain.

[0178] In some embodiments, the fourth domain is directly or indirectly connected to the second domain.

[0179] In some embodiments, the light chain of the fourth domain is directly or indirectly connected to the second domain.

[0180] In some embodiments, the heavy chain of the fourth domain is directly or indirectly connected to the second domain.

[0181] In some embodiments, the fourth domain is directly or indirectly connected to the third domain.

[0182] In some embodiments, the light chain of the fourth domain is directly or indirectly connected to the third domain.

[0183] In some embodiments, the heavy chain of the fourth domain is directly or indirectly connected to the third domain.

[0184] In some embodiments, the indirect connection comprises a connection via a linker.

[0185] In some embodiments, the linker comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 16-21.

[0186] In some embodiments, the fusion polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 700-708, 725-740, 745-774.

[0187] Third aspect

[0188] In a third aspect, the present application provides a fusion protein comprising a first domain, a second domain, and a fourth domain, wherein the first domain is an antibody or antigen binding fragment thereof that binds to HHLA2 as defined in the first aspect of the present application, the second domain is as defined in the second aspect of the present application, and the fourth domain is capable of binding to a T cell and / or NK and / or tumor cell.

[0189] In some embodiments, the fourth domain is capable of blocking the PD-L1, PD-1 pathway, or is capable of blocking other known immune checkpoint pathways, or is capable of binding to a target on a T cell / NK cell to bring the T cell / NK cell and tumor cell closer together, or is capable of binding to a TAA on other tumor cells.

[0190] In some embodiments, the fourth domain comprises the same or a different antibody or antigen binding fragment as the second domain.

[0191] In some embodiments, the fourth domain is capable of binding to one or more of the following targets: HHLA2, PD-L1, PD-L2, PD-1, OX40, 4-1BB, ICOS, TIGIT, CTLA4, LAG3, CD3, VEGF, VEGFR, CD47, HGF, Trop2, EpCAM, CCR8, CCR4, CCR5, GPRC5D, BCMA, CD19, CD20, HER-2neu, DLL1, HER-3, HER-4, EGFR, PSMA, CEA, MUC-1 (mucin), MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC7, CD123, CD33, CD30, CD38, NKG2A, Nkp36, Tim3, and 5T4.

[0192] In some embodiments, the fourth domain is capable of binding to PD-L1 and / or PD-1.

[0193] In some embodiments, the fourth domain comprises an antibody or antigen-binding fragment thereof selected from the group consisting of Sugemalimab, Atezolizumab, Permbrolizumab, and Nivolumab.

[0194] In some embodiments, the fourth domain comprises Sugemalimab or an antigen-binding fragment thereof, Atezolizumab or an antigen-binding fragment thereof, Permbrolizumab or an antigen-binding fragment thereof, or Nivolumab or an antigen-binding fragment thereof.

[0195] In some embodiments, the fourth domain comprises HCDR1, HCDR2, and / or HCDR3 of a heavy chain of an antibody, the antibody heavy chain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272, and SEQ ID NO: 276.

[0196] In some embodiments, the fourth domain comprises a heavy chain variable region VH of an antibody heavy chain, the antibody heavy chain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272, and SEQ ID NO: 276.

[0197] In some embodiments, the fourth domain comprises an antibody heavy chain, the antibody heavy chain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272, and SEQ ID NO: 276.

[0198] In some embodiments, the fourth domain comprises a LCDR1, a LCDR2, and / or a LCDR3 of a light chain of an antibody light chain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257, and SEQ ID NO: 265.

[0199] In some embodiments, the fourth domain comprises a VL of a light chain variable region of an antibody light chain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257, and SEQ ID NO: 265.

[0200] In some embodiments, the fourth domain comprises an antibody light chain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257, and SEQ ID NO: 265.

[0201] In some embodiments, the fourth domain is directly or indirectly connected to the first domain.

[0202] In some embodiments, the heavy chain of the fourth domain is directly or indirectly connected to the heavy chain of the first domain.

[0203] In some embodiments, the heavy chain of the fourth domain is directly or indirectly connected to the heavy chain of the first domain via a disulfide bond or via a complementary stereo structure (knob-into-hole, KiH).

[0204] In some embodiments, the light chain of the fourth domain is directly or indirectly connected to the heavy chain of the first domain.

[0205] In some embodiments, the heavy chain of the fourth domain is directly or indirectly connected to the light chain of the first domain.

[0206] In some embodiments, the fourth domain is directly or indirectly connected to the second domain.

[0207] In some embodiments, the light chain of the fourth domain is directly or indirectly connected to the second domain.

[0208] In some embodiments, the heavy chain of the fourth domain is directly or indirectly connected to the second domain.

[0209] In some embodiments, in the fusion polypeptide of one embodiment, the indirect connection comprises connection by a linker; preferably, the linker comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 16-21.

[0210] In some embodiments, the fusion polypeptide heavy chain comprises any one of the amino acid sequences selected from the group consisting of SEQ ID NO: 691 to SEQ ID NO: 724, SEQ ID NO: 741 to SEQ ID NO: 744, and the fusion polypeptide light chain comprises any one of the amino acid sequences selected from the group consisting of SEQ ID NO: 687 to SEQ ID NO: 690, SEQ ID NO: 725 to SEQ ID NO: 740, SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235; or, the fusion polypeptide heavy chain comprises any one of the amino acid sequences selected from the group consisting of SEQ ID NO: 603-606, SEQ ID NO: 628-631, SEQ ID NO: 636-641, and the fusion polypeptide light chain comprises any one of the amino acid sequences selected from the group consisting of SEQ ID NO: 602, SEQ ID NO: 635.

[0211] Fourth aspect

[0212] In the fourth aspect, the present application provides a fusion polypeptide comprising a first domain and a third domain, wherein the first domain is capable of blocking HHLA2 / KIR3DL3 signal, and the third domain is LAG3 or a functional fragment thereof, or a variant polypeptide thereof.

[0213] In some embodiments, the first domain has the same definition as the first domain in the first aspect of the present application.

[0214] In some embodiments, the first domain comprises a complementarity determining region or a variable region selected from RP004263 (derived from patent WO2023138579A1) or hz2D7 (derived from patent WO2020041300A1).

[0215] In some embodiments, the third domain has the same definition as the third domain in the second aspect of the application.

[0216] In some embodiments, the first domain is directly or indirectly connected to the third domain.

[0217] In some embodiments, the first domain heavy chain is directly or indirectly connected to the third domain.

[0218] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the third domain.

[0219] In some embodiments, the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the second domain.

[0220] In some embodiments, the first domain light chain is directly or indirectly connected to the third domain.

[0221] In some embodiments, the C-terminus of the first domain light chain is directly or indirectly connected to the N-terminus of the third domain.

[0222] In some embodiments, the N-terminus of the first domain light chain is directly or indirectly connected to the C-terminus of the third domain.

[0223] In some embodiments, the indirect connection comprises connection via a linker; preferably, the linker comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 16-21.

[0224] In some embodiments, the fusion polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 500-547, 583-586.

[0225] In some embodiments, the fusion polypeptide further comprises a second domain, which is capable of binding CD28 and / or CTLA4.

[0226] In some embodiments, the second domain has the same definition as the second domain in the second aspect of the application.

[0227] In some embodiments, the first domain and the second domain are directly or indirectly connected.

[0228] In some embodiments, the first domain heavy chain is directly or indirectly connected to the second domain.

[0229] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain.

[0230] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain.

[0231] In some embodiments, the first domain light chain is directly or indirectly connected to the second domain.

[0232] In some embodiments, the C-terminus of the first domain light chain is directly or indirectly connected to the N-terminus of the second domain.

[0233] In some embodiments, the N-terminus of the first domain light chain is directly or indirectly connected to the C-terminus of the second domain.

[0234] In some embodiments, the second domain and the third domain are directly or indirectly connected.

[0235] In some embodiments, the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0236] In some embodiments, the N-terminus of the second domain is directly or indirectly connected to the C-terminus of the third domain.

[0237] In some embodiments, the first domain is directly or indirectly connected to the second domain, and the second domain is directly or indirectly connected to the third domain.

[0238] In some embodiments, the C-terminus of the first domain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0239] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0240] In some embodiments, the C-terminus of the first domain light chain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0241] In some embodiments, the N-terminus of the first domain is directly or indirectly connected to the C-terminus of the second domain, and the N-terminus of the second domain is directly or indirectly connected to the C-terminus of the third domain.

[0242] In some embodiments, the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the second domain, and the N-terminus of the second domain is directly or indirectly connected to the C-terminus of the third domain.

[0243] In some embodiments, the N-terminus of the first domain light chain is directly or indirectly connected to the C-terminus of the second domain, and the N-terminus of the second domain is directly or indirectly connected to the C-terminus of the third domain.

[0244] In some embodiments, the first domain is directly or indirectly connected to the third domain, and the third domain is directly or indirectly connected to the second domain.

[0245] In some embodiments, the C-terminus of the first domain is directly or indirectly connected to the N-terminus of the third domain, and the C-terminus of the third domain is directly or indirectly connected to the N-terminus of the second domain.

[0246] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the third domain, and the C-terminus of the third domain is directly or indirectly connected to the N-terminus of the second domain.

[0247] In some embodiments, the C-terminus of the first domain light chain is directly or indirectly connected to the N-terminus of the third domain, and the C-terminus of the third domain is directly or indirectly connected to the N-terminus of the second domain.

[0248] In some embodiments, the N-terminus of the first domain is directly or indirectly connected to the C-terminus of the third domain, and the N-terminus of the third domain is directly or indirectly connected to the C-terminus of the second domain.

[0249] In some embodiments, the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the third domain, and the N-terminus of the third domain is directly or indirectly connected to the C-terminus of the second domain.

[0250] In some embodiments, the N-terminus of the first domain light chain is directly or indirectly connected to the C-terminus of the third domain, and the N-terminus of the third domain is directly or indirectly connected to the C-terminus of the second domain.

[0251] In some embodiments, the first domain is directly or indirectly connected to the second domain, and the first domain is directly or indirectly connected to the third domain.

[0252] In some embodiments, the C-terminus of the first domain is directly or indirectly connected to the N-terminus of the second domain, and the N-terminus of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0253] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the third domain.

[0254] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the third domain.

[0255] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the third domain.

[0256] In some embodiments, the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the second domain, and the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the third domain.

[0257] In some embodiments, the N-terminus of the first domain is directly or indirectly connected to the C-terminus of the second domain, and the C-terminus of the first domain is directly or indirectly connected to the N-terminus of the third domain.

[0258] In some embodiments, the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the second domain, and the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the third domain.

[0259] In some embodiments, the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the second domain, and the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the third domain.

[0260] In some embodiments, the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the second domain, and the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the third domain.

[0261] In some embodiments, the N-terminus of the first domain heavy chain is directly or indirectly connected to the C-terminus of the second domain, and the C-terminus of the first domain heavy chain is directly or indirectly connected to the N-terminus of the third domain.

[0262] In some embodiments, the indirect connection comprises a connection via a linker; preferably, the linker comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 16-21.

[0263] In some embodiments, the fusion polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 412-441, SEQ ID NOs: 448-488, SEQ ID NOs: 500-519, SEQ ID NOs: 528-582, SEQ ID NO: 774.

[0264] In some embodiments, the fusion polypeptide can further comprise a fourth domain, which is capable of binding on T cells and / or NK and / or tumor cells.

[0265] In some embodiments, the fourth domain has the same definition as the fourth domain in the second aspect of the application.

[0266] In some embodiments, the fourth domain is directly or indirectly linked to the first domain.

[0267] In some embodiments, the heavy chain of the fourth domain is directly or indirectly linked to the heavy chain of the first domain; preferably, the heavy chain of the fourth domain is directly or indirectly linked to the heavy chain of the first domain by a disulfide bond or by a complementary stereostructure (knob-into-hole, KiH); or preferably, the antigen binding fragment of the fourth domain is directly or indirectly linked to the heavy chain of the first domain or the antigen binding fragment of the first domain is directly or indirectly linked to the heavy chain of the fourth domain.

[0268] In some embodiments, the light chain of the fourth domain is directly or indirectly linked to the heavy chain of the first domain.

[0269] In some embodiments, the heavy chain of the fourth domain is directly or indirectly linked to the light chain of the first domain.

[0270] In some embodiments, the fourth domain is directly or indirectly linked to the second domain.

[0271] In some embodiments, the light chain of the fourth domain is directly or indirectly linked to the second domain.

[0272] In some embodiments, the heavy chain of the fourth domain is directly or indirectly linked to the second domain.

[0273] In some embodiments, the light chain of the fourth domain is directly or indirectly linked to the second domain.

[0274] In some embodiments, the fourth domain is directly or indirectly linked to the third domain.

[0275] In some embodiments, the light chain of the fourth domain is directly or indirectly connected to the third domain.

[0276] In some embodiments, the heavy chain of the fourth domain is directly or indirectly connected to the third domain.

[0277] In some embodiments, the indirect connection includes connection via a linker; preferably, the linker comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 16 - 21.

[0278] In some embodiments, the fusion polypeptide comprises an amino acid sequence selected from SEQ ID NO: 700 - 708, SEQ ID NO: 725 - 740, SEQ ID NO: 745 - 774.

[0279] The fifth aspect to the thirteenth aspect

[0280] In the fifth aspect, the present invention provides an immunoconjugate comprising the antibody or antigen - binding fragment described in the first aspect, and / or the fusion polypeptide described in the second aspect, the third aspect or the fourth aspect.

[0281] In the sixth aspect, the present invention provides a nucleic acid molecule encoding the antibody or antigen - binding fragment described in the first aspect, and / or the fusion polypeptide described in the second aspect, the third aspect or the fourth aspect.

[0282] In the seventh aspect, the present invention provides a vector comprising the nucleic acid molecule described in the sixth aspect.

[0283] In the eighth aspect, the present invention provides a cell comprising and / or expressing the antibody or antigen - binding fragment described in the first aspect, and / or the fusion polypeptide described in the second aspect, the third aspect or the fourth aspect, the immunoconjugate described in the fifth aspect, the nucleic acid molecule described in the sixth aspect, and / or the vector described in the seventh aspect.

[0284] In the ninth aspect, the present invention provides a composition comprising the antibody or antigen - binding fragment described in the first aspect, and / or the fusion polypeptide described in the second aspect, the third aspect or the fourth aspect, the immunoconjugate described in the fifth aspect, the nucleic acid molecule described in the sixth aspect, the vector described in the seventh aspect, and / or the cell described in the eighth aspect, and optionally a pharmaceutically acceptable carrier.

[0285] In the tenth aspect, the present invention provides a method for preparing the antibody or antigen - binding fragment described in the first aspect, and / or the fusion polypeptide described in the second aspect, the third aspect or the fourth aspect, which comprises culturing the cell described in the eighth aspect under conditions that enable the expression of the fusion polypeptide.

[0286] In an eleventh aspect, the present application provides a method of blocking the interaction of HHLA2 with KIR3DL3, comprising administering an effective amount of the antibody or antigen binding fragment of the first aspect, and / or the fusion polypeptide of the second, third or fourth aspect.

[0287] In a twelfth aspect, the present application provides a method of inhibiting the growth and / or proliferation of a tumor or tumor cell, comprising administering an effective amount of the antibody or antigen binding fragment of the first aspect, and / or the fusion polypeptide of the second, third or fourth aspect, the immunoconjugate of the fifth aspect, the nucleic acid molecule of the sixth aspect, the vector of the seventh aspect, the cell of the eighth aspect, and / or the composition of the ninth aspect.

[0288] In a thirteenth aspect, the present application also provides the use of the antibody or antigen binding fragment of the first aspect, and / or the fusion polypeptide of the second, third or fourth aspect, the immunoconjugate of the fifth aspect, the nucleic acid molecule of the sixth aspect, the vector of the seventh aspect, the cell of the eighth aspect, and / or the composition of the ninth aspect in the manufacture of a medicament for preventing, ameliorating and / or treating a tumor.

[0289] In some embodiments, wherein the tumor comprises a solid tumor and / or a hematological tumor; preferably, the tumor is selected from the group consisting of a colon tumor, a breast tumor, a lung tumor, a gastric tumor, a melanoma, a head and neck tumor, a lymphoma, a nasopharyngeal tumor, a cervical tumor, an esophageal tumor, a renal tumor, a skin squamous carcinoma, an endometrial tumor, a liver tumor, a bladder tumor, a urothelial tumor and a skin tumor.

[0290] DETAILED DESCRIPTION

[0291] The technical problem to be solved by the present application is to provide a new therapeutic regimen for tumors using a new agent with the ability to synergistically block the HHLA2 / KIR3DL3 pathway and enhance T cell activation in order to overcome the limited effect of anti-B7-H7 antibodies on tumor treatment in existing products. The development of a new agent with the ability to synergistically block the HHLA2 / KIR3DL3 pathway, enhance T cell activation and / or improve antigen presenting cell activation for the clinical treatment of tumors can potentially bring more benefits to more tumor patients.

[0292] The present application provides a single functional anti-HHLA2 antibody, which has the effect of blocking the HHLA2 / KIR3DL3 pathway to enhance T cell activation / NK cell killing activity. The present application also provides a fusion polypeptide, which can comprise (i) an anti-HHLA2 (HERV-HLTR-associating 2, B7-H7) antibody or antigen binding fragment thereof, or / and (ii) an immunoglobulin Fc domain, or / and (iii) a CD86 extracellular domain (ECD), or / and (iv) a LAG3 extracellular domain, or / and (v) an anti-PD-L1 / PD-1 antibody or antigen binding fragment thereof, and the present application provides polynucleotides expressing the fusion polypeptides; the present application provides methods for inducing and / or enhancing immunity using the fusion polypeptides, and methods for treating diseases (e.g., cancer).

[0293] The present application provides a class of bifunctional and / or multifunctional fusion polypeptides that simultaneously interfere with, inhibit or block the HHLA2 / KIR3DL3 signal transduction pathway and / or synergistically stimulate antigen-presenting cell activation and / or synergistically stimulate T cell activation, which can effectively agonize T cells to enhance immune response and / or agonize antigen-presenting cells, and can have a potential effect of killing tumors, thereby achieving therapeutic effects in patients with tumors that have high expression of HHLA2, particularly in patients with tumors that have high expression of HHLA2.

[0294] In one aspect, the present application provides an anti-B7-H7 antibody or antigen binding fragment thereof, which comprises a heavy chain variable region (VH) and / or a light chain variable region (VL). Wherein the VL comprises the following complementarity determining regions (CDRs) or mutations thereof: the amino acid sequence of LCDR1 is as shown in SEQ ID NO: 245, 253, 261, the amino acid sequence of LCDR2 is as shown in SEQ ID NO: 246, 254, and the amino acid sequence of LCDR3 is as shown in SEQ ID NO: 247, 255, 271; the VH comprises the following CDRs or mutations thereof: the amino acid sequence of HCDR1 is as shown in SEQ ID NO: 242, 250, 258, 266, 273, 277, the amino acid sequence of HCDR2 is as shown in SEQ ID NO: 243, 251, 259, 267, 274, 278, and the amino acid sequence of HCDR3 is as shown in SEQ ID NO: 244, 252, 260, 268, 275, 279, 296.

[0295] In this application, the terms "insertion, deletion, or substitution of amino acids" or "amino acid mutation" refer to an amino acid change in a variant sequence relative to the original amino acid sequence, including insertion, deletion, or substitution. For example, a mutation of a CDR may involve a mutation of 1 to 3 amino acids, and these CDRs may optionally involve the same or different numbers of amino acid residues. For example, CDR1 may be mutated by one amino acid, while CDR2 and CDR3 remain unchanged.

[0296] Preferably, the amino acid sequences of HCDR1, HCDR2, and HCDR3 are as follows:

[0297] (1) HCDR1 is SEQ ID NO:242, HCDR2 is SEQ ID NO:243, and HCDR3 is SEQ ID NO:244;

[0298] (2) HCDR1 is SEQ ID NO:250, HCDR2 is SEQ ID NO:251, and HCDR3 is SEQ ID NO:252;

[0299] (3) HCDR1 is SEQ ID NO:258, HCDR2 is SEQ ID NO:259, and HCDR3 is SEQ ID NO:260;

[0300] (4) HCDR1 is SEQ ID NO:266, HCDR2 is SEQ ID NO:267, and HCDR3 is SEQ ID NO:268;

[0301] (5) HCDR1 is SEQ ID NO:273, HCDR2 is SEQ ID NO:274, and HCDR3 is SEQ ID NO:275;

[0302] (6)HCDR1 is SEQ ID NO:277, HCDR2 is SEQ ID NO:278, and HCDR3 is SEQ ID NO:279;

[0303] (7)HCDR1 is SEQ ID NO:273, HCDR2 is SEQ ID NO:274, and HCDR3 is SEQ ID NO:296.

[0304] Preferably, the amino acid sequences of LCDR1, LCDR2, and LCDR3 are as follows:

[0305] (1) LCDR1 is SEQ ID NO: 245, LCDR2 is SEQ ID NO: 246, and LCDR3 is SEQ ID NO: 247;

[0306] (2) LCDR1 is SEQ ID NO: 253, LCDR2 is SEQ ID NO: 254, and LCDR3 is SEQ ID NO: 255;

[0307] (3) LCDR1 is SEQ ID NO: 261, LCDR2 is SEQ ID NO: 254, and LCDR3 is SEQ ID NO: 255;

[0308] (4) LCDR1 is SEQ ID NO: 261, LCDR2 is SEQ ID NO: 254, and LCDR3 is SEQ ID NO: 271.

[0309] Preferably, the combinations of HCDR1, HCDR2, HCDR3 and LCDR1, LCDR2, LCDR3 are as follows: (1) HCDR1 is SEQ ID NO: 242, HCDR2 is SEQ ID NO: 243, HCDR3 is SEQ ID NO: 244, LCDR1 is SEQ ID NO: 245, LCDR2 is SEQ ID NO: 246, and LCDR3 is SEQ ID NO: 247;

[0310] (2) HCDR1 is SEQ ID NO: 250, HCDR2 is SEQ ID NO: 251, HCDR3 is SEQ ID NO: 252, LCDR1 is SEQ ID NO: 253, LCDR2 is SEQ ID NO: 254, and LCDR3 is SEQ ID NO: 255;

[0311] (3) HCDR1 is SEQ ID NO: 258, HCDR2 is SEQ ID NO: 259, HCDR3 is SEQ ID NO: 260, LCDR1 is SEQ ID NO: 261, LCDR2 is SEQ ID NO: 254, and LCDR3 is SEQ ID NO: 255;

[0312] (4) HCDR1 is SEQ ID NO: 266, HCDR2 is SEQ ID NO: 267, HCDR3 is SEQ ID NO: 268, LCDR1 is SEQ ID NO: 261, LCDR2 is SEQ ID NO: 254, and LCDR3 is SEQ ID NO: 271.

[0313] In addition, preferably, the amino acid sequences of HCDR1, HCDR2, HCDR3 can be any combination of the following:

[0314] (1) HCDR1 is SEQ ID NO: 273, HCDR2 is SEQ ID NO: 274, and HCDR3 is SEQ ID NO: 275;

[0315] (2) HCDR1 is SEQ ID NO: 277, HCDR2 is SEQ ID NO: 278, and HCDR3 is SEQ ID NO: 279;

[0316] (3) HCDR1 is SEQ ID NO: 273, HCDR2 is SEQ ID NO: 274, and HCDR3 is SEQ ID NO: 296.

[0317] In an embodiment of the application, the VL comprises any one of the amino acid sequences of SEQ ID NOs: 281, 283, 285, 287, 289, 291, 302, 322, 332, or a mutated version thereof.

[0318] In an embodiment of the application, the VL comprises any one of the amino acid sequences of SEQ ID NOs: 281, 283, 285, 287, 289, 291, 302, 322, 332, or a mutated version thereof.

[0319] Preferably, the VL comprises a light chain variable region framework region (VL FWR) derived from a human antibody light chain variable region framework region, the encoding gene of which is preferably derived from germline V gene IGKV1-NL1*01, IGKV1-5*01, IGKV3-20*01. More preferably, the VL FWR comprises any one of the following amino acid sequences or a mutated version thereof:

[0320] VL FWR1: SEQ ID NO: 303, 323

[0321] VL FWR2: SEQ ID NO: 304, 324

[0322] VL FWR3: SEQ ID NO: 305, 325, 335

[0323] VL FWR4: SEQ ID NO: 306

[0324] The mutation refers to an insertion, deletion, substitution or duplication of 3, 2 or 1 amino acids in the amino acid sequence of the VL FWR.

[0325] Preferably, the VH comprises a heavy chain variable region framework region (VH FWR) which is derived from a human antibody heavy chain variable region framework region, the encoding gene of which is preferably derived from the germline V gene IGHV1-46*01, IGHV1-2*02, IGHV1-3*01.

[0326] More preferably, the VH FWR comprises any one of the following amino acid sequences or a mutated version thereof:

[0327] VH FWR1: SEQ ID NO: 298

[0328] VH FWR2: SEQ ID NO: 299

[0329] VH FWR3: SEQ ID NO: 300, 310, 320, 340

[0330] VH FWR4: SEQ ID NO: 301

[0331] The mutations refer to insertions, deletions, substitutions, or repeats of 3, 2, or 1 amino acids in the amino acid sequence of the VH FWRs. In a preferred embodiment, the VL comprises the amino acid sequence of SEQ ID NO: 281 and the VH comprises the amino acid sequence of SEQ ID NO: 280. In a preferred embodiment, the VL comprises the amino acid sequence of SEQ ID NO: 283 and the VH comprises the amino acid sequence of SEQ ID NO: 282. In a preferred embodiment, the VL comprises the amino acid sequence of SEQ ID NO: 285 and the VH comprises the amino acid sequence of SEQ ID NO: 284. In a preferred embodiment, the VL comprises the amino acid sequence of SEQ ID NO: 287 and the VH comprises the amino acid sequence of SEQ ID NO: 286. In a preferred embodiment, the VL comprises the amino acid sequence of SEQ ID NO: 289 and the VH comprises the amino acid sequence of SEQ ID NO: 288. In a preferred embodiment, the VL comprises the amino acid sequence of SEQ ID NO: 291 and the VH comprises the amino acid sequence of SEQ ID NO: 290. In a preferred embodiment, the VL comprises the amino acid sequence of SEQ ID NO: 302 and the VH comprises the amino acid sequence of SEQ ID NO: 297. In a preferred embodiment, the VL comprises the amino acid sequence of SEQ ID NO: 302 and the VH comprises the amino acid sequence of SEQ ID NO: 307. In a preferred embodiment, the VL comprises the amino acid sequence of SEQ ID NO: 322 and the VH comprises the amino acid sequence of SEQ ID NO: 317. In a preferred embodiment, the VL comprises the amino acid sequence of SEQ ID NO: 332 and the VH comprises the amino acid sequence of SEQ ID NO: 317. In a preferred embodiment, the VL comprises the amino acid sequence of SEQ ID NO: 322 and the VH comprises the amino acid sequence of SEQ ID NO: 337. In a preferred embodiment, the VL comprises the amino acid sequence of SEQ ID NO: 332 and the VH comprises the amino acid sequence of SEQ ID NO: 337. In a preferred embodiment, the VL comprises the amino acid sequence of SEQ ID NO: 332 and the VH comprises the amino acid sequence of SEQ ID NO: 357.

[0332] In a preferred embodiment, the VH comprises an amino acid sequence as set forth in SEQ ID NO: 292. In a preferred embodiment, the VH comprises an amino acid sequence as set forth in SEQ ID NO: 293. In a preferred embodiment, the VH comprises an amino acid sequence as set forth in SEQ ID NO: 295.

[0333] The single-function antibody heavy chain comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 240, 248, 256, 264, 272, 276, 367-372. The single-function antibody light chain comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 241, 249, 257, 265, 373-375.

[0334] Preferably, the single-function antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 240, and the single-function antibody light chain comprises an amino acid sequence as set forth in SEQ ID NO: 241.

[0335] Preferably, the single-function antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 248, and the single-function antibody light chain comprises an amino acid sequence as set forth in SEQ ID NO: 249.

[0336] Preferably, the single-function antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 256, and the single-function antibody light chain comprises an amino acid sequence as set forth in SEQ ID NO: 257.

[0337] Preferably, the single-function antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 264, and the single-function antibody light chain comprises an amino acid sequence as set forth in SEQ ID NO: 265.

[0338] Preferably, the single-function antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 368, and the single-function antibody light chain comprises an amino acid sequence as set forth in SEQ ID NO: 373.

[0339] Preferably, the single-function antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 369, and the single-function antibody light chain comprises an amino acid sequence as set forth in SEQ ID NO: 373.

[0340] Preferably, the single-function antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 370, and the single-function antibody light chain comprises an amino acid sequence as set forth in SEQ ID NO: 374.

[0341] Preferably, the single-function antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 370, and the single-function antibody light chain comprises an amino acid sequence as set forth in SEQ ID NO: 375.

[0342] Preferably, the single-function antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 371, and the single-function antibody light chain comprises an amino acid sequence as set forth in SEQ ID NO: 374.

[0343] Preferably, the single-function antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 371, and the single-function antibody light chain comprises an amino acid sequence as set forth in SEQ ID NO: 375.

[0344] Preferably, the single-function antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 372, and the single-function antibody light chain comprises an amino acid sequence as set forth in SEQ ID NO: 375. Preferably, the single-function antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 272.

[0345] Preferably, the single-function antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 276.

[0346] Preferably, the single-function antibody heavy chain comprises an amino acid sequence as set forth in SEQ ID NO: 367.

[0347] Preferably, the anti-B7-H7 antibody or antigen-binding fragment thereof described in the present application can be a recombinant antibody, a single-domain antibody, a heavy chain antibody, a chimeric antibody, a humanized antibody, a fully human antibody, a bispecific antibody, a trispecific antibody, an antibody-drug conjugate (ADC), an Fc fusion protein, a monoclonal antibody, or a polyclonal antibody. Preferably, the anti-B7-H7 antibody or antigen-binding fragment thereof described in the present application is selected from one or more of the following group: Fab, Fab', Fv fragment, F(ab')2, F(ab)2, scFv, di-scFv, VHH, dAb, and single-chain bivalent antibody (sdAb).

[0348] Preferably, the anti-B7-H7 antibody or antigen-binding fragment thereof of the present application can be obtained by hybridoma technology, phage display technology, yeast display technology, mammalian cell expression system, E. coli expression system, transgenic animal or plant expression system, etc.

[0349] Preferably, the anti-B7-H7 antibody or antigen-binding fragment thereof of the present application can be a natural antibody or an engineered antibody, such as an Fc-optimized antibody, a glycosylation-modified antibody, a PEG-modified antibody, an antibody with enhanced stability, or an immunotoxin fusion antibody.

[0350] In another aspect, the present application provides a CD86 variant polypeptide comprising an amino acid substitution mutant of humanized CD86. The CD86 variant polypeptide of the present application can be used to enhance or inhibit the interaction of CD86 with CD28 or CTLA-4 to modulate immune response, suitable for cancer immunotherapy or treatment of autoimmune diseases.

[0351] The content related to CD86 mutants described in PCT / CN2023 / 134527 is incorporated by reference into the present application.

[0352] 1. A CD86 extracellular domain IgV domain mutant

[0353] In one embodiment, the CD86 variant polypeptide comprises an extracellular domain IgV domain amino acid substitution mutant of CD86, which mutant comprises at least 1, 2, 3, 4, 5 or more mutations in the following amino acid positions: A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

[0354] In another embodiment, the CD86 variant polypeptide comprises at least one of the following combinations of mutations: Q25I / F33L / H90I, Q25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V, Q25V / F33L / H90V, Q25I / F33V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F33L / H90I, A13L / Q25V / F33L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M60R / H90I, Q25V / F33L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F, Q25I / F33A / H90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13F / Q25I / F33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I, and Q25I / F33L / H90M.

[0355] In a preferred embodiment, the CD86 variant polypeptide comprises the specific combination of mutations Q25I / F33L / H90I.

[0356] 2. CD86 extracellular domain mutants

[0357] In another embodiment, the CD86 variant polypeptide comprises an extracellular domain amino acid substitution mutant of humanized CD86 comprising at least 1, 2, 3, 4, 5, or more mutations of the following amino acid positions: A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

[0358] In another embodiment, the amino acid substitution mutants of the CD86 variant polypeptides can comprise, but are not limited to, the following combinations of mutations: Q25I / F33L / H90I, 25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V, Q25V / F33L / H90V, Q25I / F33V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F33L / H90I, A13L / Q25V / F33L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M60R / H90I, Q25V / F33L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F, Q25I / F33A / H90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13F / Q25I / F33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I, and Q25I / F33L / H90M.

[0359] In a preferred embodiment, the CD86 variant polypeptide comprises the specific combination of mutations Q25I / F33L / H90I.

[0360] In one embodiment of the CD86 variant polypeptide, the CD86 variant polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 22 to SEQ ID NO: 87.

[0361] In certain embodiments, the CD86 variant polypeptide can be further modified, such as glycosylation optimization, Fc fusion, PEG modification, or other protein engineering, to optimize its immune activity or stability.

[0362] In another aspect, the present application provides a CD80 variant polypeptide comprising an amino acid substitution mutation of humanized CD80. The content related to CD80 mutants described in PCT / CN2023 / 102271 is incorporated by reference into the present application.

[0363] In another aspect, the present application provides a LAG3 variant polypeptide, which is based on human LAG3 and comprises specific truncation and / or mutation. The relevant content about LAG3 variant in PCT / CN2023 / 134527 and CN2024106601424 is incorporated by reference into the present application.

[0364] In one embodiment, the LAG3 variant polypeptide comprises a truncation based on wild-type human LAG3 ectodomain polypeptide.

[0365] In one embodiment, the LAG3 variant polypeptide comprises an amino acid sequence that is 0-124 amino acids shorter at the N-terminus than the wild-type human LAG3 extracellular region polypeptide, e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124 amino acids shorter.and the C-terminus terminates at a position corresponding to any of amino acid positions 121-167, e.g., amino acid positions 121, 122-146, 122-167, 123-167, 124-167, 125-167, 126-167, 127-167, 128-167, 129-167, 130-167, 131-167, 132-167, 133-167, 134-167, 135-167, 136-167, 137-167, 138-167, 139-167, 140-167, 141-167, 142-167, 143-167, 144-167, 145-167, 146-167, 147-167, 148-167, 149-167, 150-167, 151-167, 152-167, 153-167, 154-167, 155-167, 156-167, 157-167, 158-167, 159-167, 160-167, 161-167, 162-167, 163-167, 164-167, 165-167, 166-167, or 167 of the wild-type LAG3 ectodomain polypeptide, e.g., the C-terminus terminates at a position corresponding to amino acid position 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 of the wild-type LAG3 ectodomain polypeptide.

[0366] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid sequence that is 0, 5, 21, 37, 45, 60, 71, 74, 79, 81, 84, 89, 94, 99, 104, 109, or 114 amino acids shorter at the N-terminus than the wild-type human LAG3 ectodomain polypeptide.

[0367] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid sequence that is 0, 5, 21, 37, 45, 60, 71, 74, 81, or 99 amino acids shorter at the N-terminus than the wild-type human LAG3 ectodomain polypeptide.

[0368] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid sequence that is based on the wild-type human LAG3 extracellular region polypeptide truncated by 0, 5, 21, 37, 45, 60, 71, or 74 amino acids at the N-terminus.

[0369] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid sequence that is based on the wild-type human LAG3 extracellular region polypeptide truncated by 0, 5, 21, 37, 45, 60, 71, or 74 amino acids at the N-terminus.

[0370] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid sequence that is based on the wild-type human LAG3 extracellular region polypeptide truncated by 0, 5, 21, 37, 45, 60, 71, or 74 amino acids at the N-terminus.

[0371] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid sequence that is based on the wild-type human LAG3 extracellular region polypeptide truncated by 0, 5, 21, 37, 45, 60, 71, or 74 amino acids at the N-terminus.

[0372] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid sequence that is based on the wild-type human LAG3 extracellular region polypeptide truncated by 0, 5, 21, 37, 45, 60, 71, or 74 amino acids at the N-terminus.

[0373] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid sequence that is based on the wild-type human LAG3 extracellular region polypeptide truncated by 0, 5, 21, 37, 45, 60, 71, or 74 amino acids at the N-terminus.

[0374] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid sequence that is based on the wild-type human LAG3 extracellular region polypeptide truncated by 0, 5, 21, 37, 45, 60, 71, or 74 amino acids at the N-terminus.

[0375] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid sequence that is based on the wild-type human LAG3 extracellular region polypeptide truncated by 0, 5, 21, 37, 45, 60, 71, or 74 amino acids at the N-terminus.

[0376] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid sequence that is based on the wild-type human LAG3 ectodomain polypeptide truncated by 0, 5, 21, 37, 45, 60, 71, 74, 81, or 99 amino acids at the N-terminus and terminates at the C-terminus at amino acid position 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 of the wild-type human LAG3 ectodomain polypeptide.

[0377] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid sequence that is based on the wild-type human LAG3 ectodomain polypeptide truncated by 0, 5, 21, 37, 45, 60, 71, or 74 amino acids at the N-terminus and terminates at the C-terminus at amino acid position 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 of the wild-type human LAG3 ectodomain polypeptide.

[0378] In one embodiment of the LAG3 variant, the LAG3 variant polypeptide comprises an amino acid sequence that is based on the wild-type human LAG3 ectodomain polypeptide truncated by 125-145 amino acids at the N-terminus, e.g., 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, or 145 amino acids; and terminates at the C-terminus at a position of the wild-type LAG3 ectodomain polypeptide that corresponds to any of amino acid positions 148-167 of the wild-type LAG3 ectodomain polypeptide, e.g., a position that corresponds to any of 148-167, 149-167, 150-167, 151-167, 152-167, 153-167, 154-167, 155-167, 156-167, 157-167, 158-167, 159-167, 160-167, 161-167, 162-167, 163-167, 164-167, 165-167, 166-167, e.g., terminates at the C-terminus at a position that corresponds to amino acid position 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 of the wild-type LAG3 ectodomain polypeptide.

[0379] In one embodiment, the LAG3 variant polypeptide comprises a truncation of 0-124 amino acids at the N-terminus, e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124 amino acids, based on the wild-type human LAG3 extracellular region polypeptide; and terminates at the C-terminus at a position that is between amino acid positions 1-121 of the wild-type LAG3 extracellular region polypeptide, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161,for example, the position corresponding to any of the positions of 1-121, 2-121, 3-121, 4-121, 5-121, 6-121, 7-121, 8-121, 9-121, 10-121, 11-121, 12-121, 13-121, 14-121, 15-121, 16-121, 17-121, 18-121, 19-121, 20-121, 21-121, 22-121, 23-121, 24-121, 25-121, 26-121, 27-121, 28-121, 29-121, 30-121, 31-121, 32-121, 33-121, 34-121, 35-121, 36-121, 37-121, 38-121, 39-121, 40-121, 41-121, 42-121, 43-121, 44-121, 45-121, 46-121, 47-121, 48-121, 49-121, 50-121, 51-121, 52-121, 53-121, 54-121, 55-121, 56-121, 57-121, 58-121, 59-121, 60-121, 61-121, 62-121, 63-121, 64-121, 65-121, 66-121, 67-121, 68-121, 69-121, 70-121, 71-121, 72-121, 73-121, 74-121, 75-121, 76-121, 77-121, 78-121, 79-121, 80-121, 81-121, 82-121, 83-121, 84-121, 85-121, 86-121, 87-121, 88-121, 89-121, 90-121, 91-121, 92-121, 93-121, 94-121, 95-121, 96-121, 97-121, 98-121, 99-121, 100-121, 101-121, 102-121, 103-121, 104-121, 105-121, 106-121, 107-121, 108-121, 109-121, 110-121, 111-121, 112-121, 113-121, 114-121, 115-121, 116-121, 117-121, 118-121, 119-121, or 120-121,For example, the C-terminus terminates at a position corresponding to amino acid position 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, or 121 of the wild-type LAG3 extracellular domain polypeptide.

[0380] In one embodiment, the LAG3 variant polypeptide comprises an amino acid mutation at a position corresponding to amino acid position 97.

[0381] In one embodiment, the LAG3 variant polypeptide comprises an amino acid mutation at a position corresponding to amino acid position 97.

[0382] In one embodiment, the LAG3 variant polypeptide comprises an amino acid mutation at a position corresponding to amino acid position 97.

[0383] In one embodiment, the LAG3 variant polypeptide comprises an amino acid mutation at a position corresponding to amino acid position 97.

[0384] In one embodiment, the LAG3 variant polypeptide comprises an amino acid mutation at a position corresponding to amino acid position 97.

[0385] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid mutation at a position corresponding to R110, R113, R119, R129, G130, and / or R141.

[0386] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid mutation at a position corresponding to R110, R113, R119, R129, G130, and / or R141.

[0387] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation at R113 to K113.

[0388] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation at R119 to K119.

[0389] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation at R129 to K129.

[0390] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation at G130 to P130, or A130, or T130, or Y130, or S130.

[0391] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation at R141 to K141.

[0392] In certain embodiments, the LAG3 variant polypeptide comprises an amino acid site mutation at R141 to K141 and / or G130 to P130.

[0393] In certain preferred embodiments, the truncated LAG3 variant polypeptide variant has at least one feature selected from the group consisting of:

[0394] (1) N-terminally truncated by 74 amino acids and C-terminally ending at a position corresponding to amino acid position 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166 or 167 of the wild-type LAG3 extracellular region polypeptide; wherein, preferably, C-terminally ending at a position corresponding to amino acid position 122, 129, 136, 146, 156, 161 of the wild-type LAG3 extracellular region polypeptide;

[0395] (2) N-terminally truncated by 74 amino acids, the Arg amino acid at position 97 mutated to Glu amino acid, and C-terminally ending at a position corresponding to amino acid position 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166 or 167 of the wild-type LAG3 extracellular region polypeptide; wherein, preferably, C-terminally ending at a position corresponding to amino acid position 122, 129, 136, 146, 156, 161 of the wild-type LAG3 extracellular region polypeptide;

[0396] (3) N-terminal truncation of 5 amino acids and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0397] (4) N-terminal truncation of 5 amino acids, mutation of the Arg amino acid at position 97 to a Glu amino acid, and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0398] (5) N-terminal truncation of 21 amino acids and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0399] (6) N-terminal truncation of 21 amino acids, mutation of the Arg amino acid at position 97 to a Glu amino acid, and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0400] (7) N-terminal truncation of 37 amino acids and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0401] (8) N-terminal truncation of 37 amino acids, mutation of the Arg amino acid at position 97 to a Glu amino acid, and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0402] (9) N-terminal truncation of 45 amino acids and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0403] (10) N-terminal truncation of 45 amino acids, mutation of the Arg amino acid at position 97 to a Glu amino acid, and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0404] (11) N-terminal truncation of 60 amino acids and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0405] (12) N-terminal truncation of 60 amino acids, mutation of the Arg amino acid at position 97 to a Glu amino acid, and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0406] (13) N-terminal truncation of 71 amino acids and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0407] (14) N-terminal truncation of 71 amino acids, mutation of the Arg amino acid at position 97 to a Glu amino acid, and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0408] (15) N-terminal truncation of 79 amino acids and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0409] (16) N-terminal truncation of 84 amino acids and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0410] (17) N-terminal truncation of 89 amino acids and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0411] (18) N-terminal truncation of 94 amino acids and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0412] (19) N-terminal truncation of 99 amino acids and C-terminal truncation at a position corresponding to amino acid position 146, 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0413] (20) N-terminal truncation of 99 amino acids and C-terminal truncation at amino acid position 146, with mutations introduced at R129, and / or G130, and / or R141;

[0414] (21) N-terminal truncation of 104 amino acids and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0415] (22) N-terminal truncation of 109 amino acids and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0416] (23) N-terminal truncation of 114 amino acids and C-terminal truncation at a position corresponding to amino acid position 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0417] (24) N-terminally truncated by 0 amino acids and C-terminally truncated at a position corresponding to amino acid position 122, 129, 136, 146, 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0418] (25) N-terminally truncated by 0 amino acids, mutated at position 97 from Arg to Glu, and C-terminally truncated at a position corresponding to amino acid position 122, 129, 136, 146, 156, 161 or 167 of the wild-type LAG3 ectodomain polypeptide;

[0419] (26) LAG3 polypeptide variant N-terminally truncated by 81 amino acids and C-terminally truncated at amino acid position 121, and comprising a mutation at R110, and / or R113, and / or R119;

[0420] (27) LAG3 polypeptide variant N-terminally truncated by 81 amino acids and C-terminally truncated at amino acid position 146, and comprising a mutation at R110, and / or R113, and / or R119, and / or R129, and / or G130, and / or R141.

[0421] In an embodiment, the LAG3 variant polypeptide is selected from the group consisting of the amino acid sequences set forth in SEQ ID NO: 88 to SEQ ID NO: 227.

[0422] In another aspect, the present application provides a fusion polypeptide, which comprises a first domain and a second domain. The first domain is capable of blocking HHLA2 / KIR3DL3 signaling, and the second domain is capable of binding CD28 and / or CTLA4.

[0423] In an embodiment, the fusion polypeptide, the first domain is capable of binding HHLA2.

[0424] In an embodiment, the fusion polypeptide, the first domain comprises an antibody or an antigen-binding fragment thereof.

[0425] In one embodiment, the fusion polypeptide, the first domain has the following CDRs or mutations thereof: LCDR1 selected from SEQ ID NO: 245, 253, 261, LCDR2 selected from SEQ ID NO: 246, 254, 262, LCDR3 selected from SEQ ID NO: 247, 255, 263, and HCDR1 selected from SEQ ID NO: 242, 250, 258, 266, 273, 277, HCDR2 selected from SEQ ID NO: 243, 251, 259, 267, 274, 278, and HCDR3 selected from SEQ ID NO: 244, 252, 260, 268, 275, 279, 296, wherein the mutations are insertions, deletions, or substitutions of 3, 2, or 1 amino acids in the amino acid sequence of the CDRs.

[0426] In one embodiment, the first domain has the amino acid sequence of the HCDR1 set out in SEQ ID NO: 242, the amino acid sequence of the HCDR2 set out in SEQ ID NO: 243, the amino acid sequence of the HCDR3 set out in SEQ ID NO: 244, the amino acid sequence of the LCDR1 set out in SEQ ID NO: 245, the amino acid sequence of the LCDR2 set out in SEQ ID NO: 246, and the amino acid sequence of the LCDR3 set out in SEQ ID NO: 247; or the amino acid sequence of the HCDR1 set out in SEQ ID NO: 250, the amino acid sequence of the HCDR2 set out in SEQ ID NO: 251, the amino acid sequence of the HCDR3 set out in SEQ ID NO: 252, the amino acid sequence of the LCDR1 set out in SEQ ID NO: 253, the amino acid sequence of the LCDR2 set out in SEQ ID NO: 254, and the amino acid sequence of the LCDR3 set out in SEQ ID NO: 255; or the amino acid sequence of the HCDR1 set out in SEQ ID NO: 258, the amino acid sequence of the HCDR2 set out in SEQ ID NO: 259, the amino acid sequence of the HCDR3 set out in SEQ ID NO: 260, the amino acid sequence of the LCDR1 set out in SEQ ID NO: 261, the amino acid sequence of the LCDR2 set out in SEQ ID NO: 254, and the amino acid sequence of the LCDR3 set out in SEQ ID NO: 255; or the amino acid sequence of the HCDR1 set out in SEQ ID NO: 266, the amino acid sequence of the HCDR2 set out in SEQ ID NO: 267, the amino acid sequence of the HCDR3 set out in SEQ ID NO: 268, the amino acid sequence of the LCDR1 set out in SEQ ID NO: 261, the amino acid sequence of the LCDR2 set out in SEQ ID NO: 254, and the amino acid sequence of the LCDR3 set out in SEQ ID NO: 271; or the amino acid sequence of the HCDR1 set out in SEQ ID NO: 273, the amino acid sequence of the HCDR2 set out in SEQ ID NO: 274, and the amino acid sequence of the HCDR3 set out in SEQ ID NO: 275; or the amino acid sequence of the HCDR1 set out in SEQ ID NO: 277, the amino acid sequence of the HCDR2 set out in SEQ ID NO: 278, and the amino acid sequence of the HCDR3 set out in SEQ ID NO: 279.or the amino acid sequence of the HCDR1 is set forth in SEQ ID NO:273, the amino acid sequence of the HCDR2 is set forth in SEQ ID NO:274, and the amino acid sequence of the HCDR3 is set forth in SEQ ID NO:296.

[0427] In one embodiment, the first domain comprises a heavy chain variable region (VH) and a light chain variable region (VL) of an antibody. The amino acid sequence of the VH is selected from the group consisting of SEQ ID NO: 280, 282, 284, 286, 288, 290, 292-293, 295, 297, 307, 317, 337, 357, and the amino acid sequence of the VL is selected from the group consisting of SEQ ID NO: 281, 283, 285, 287, 289, 291, 302, 322, 332. Particular VH / VL combinations include, but are not limited to, SEQ ID NO: 280 / 281, 282 / 283, 284 / 285, 286 / 287, 288 / 289, 290 / 291, 297 / 302, 307 / 302, 317 / 322, 317 / 332, 337 / 322, 337 / 332, 357 / 332.

[0428] In another embodiment, the first domain comprises a heavy chain variable region VHH of a single domain antibody, the amino acid sequence of which is selected from the group consisting of SEQ ID NO: 292, 293, 295.

[0429] In a further embodiment, the first domain comprises a complete antibody heavy chain and light chain. The first domain antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 240, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 241; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 248, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 249; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 256, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 257; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 264, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 265; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 368, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 373; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 369, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 373; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 370, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 374; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 370, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 375; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 371, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 374; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 371, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 375; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 372, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 375.

[0430] In another embodiment, the first domain comprises a complete antibody heavy chain. The first domain antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 272; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 276; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 367.

[0431] In another embodiment, the first domain comprises an antibody or antigen binding fragment thereof selected from RP004263 (disclosed in patent WO2023138579A1) and hz2D7 (disclosed in patent WO2020041300A1).

[0432] In another embodiment, the first domain comprises a heavy chain variable region (VH) of an antibody, wherein the heavy chain variable region comprises HCDR1, HCDR2 and / or HCDR3, and the amino acid sequence thereof is selected from the group consisting of SEQ ID NO: 236 and SEQ ID NO: 238.

[0433] In another embodiment, the first domain comprises a complete heavy chain of an antibody, and the amino acid sequence of the antibody heavy chain is selected from the group consisting of SEQ ID NO: 236 and SEQ ID NO: 238.

[0434] In another embodiment, the first domain comprises a light chain variable region (VL) of an antibody, wherein the light chain variable region comprises LCDR1, LCDR2 and / or LCDR3, and the amino acid sequence thereof is selected from the group consisting of SEQ ID NO: 237 and SEQ ID NO: 239.

[0435] In another embodiment, the first domain comprises a complete light chain or an antigen binding fragment thereof of an antibody, and the amino acid sequence of the antibody light chain is selected from the group consisting of SEQ ID NO: 237 and SEQ ID NO: 239. In one embodiment of the fusion polypeptide, the first domain antibody is selected from the group consisting of a recombinant antibody, a single domain antibody, a heavy chain antibody, a chimeric antibody, a humanized antibody, a fully human antibody, a bispecific antibody, a trispecific antibody, an antibody-drug conjugate (ADC), an Fc fusion protein, a monoclonal antibody or a polyclonal antibody.

[0436] Preferably, the anti-B7-H7 antibody or antigen binding fragment thereof in the present application is selected from one or more of the group consisting of a Fab, Fab', Fv fragment, F(ab')2, F(ab)2, scFv, di-scFv, VHH and, dAb and sdAb.

[0437] In one embodiment of the fusion polypeptide, the second domain comprises CD86 or CD80 or a functionally active fragment thereof, or / and a variant of CD86 or CD80.

[0438] In one embodiment of the fusion polypeptide, the second domain is selected from the group consisting of CD86 or CD80 or a functionally active fragment thereof derived from human or mouse.

[0439] In one embodiment of the fusion polypeptide, the second domain comprises an IgV domain of CD86 or CD80 or a functionally active fragment thereof.

[0440] In one embodiment of the fusion polypeptide, the second domain comprises an extracellular domain of CD86 or CD80 or a functionally active fragment thereof.

[0441] In an embodiment, the fusion polypeptide, the second domain comprises a CD86 variant polypeptide, the mutant comprising an amino acid substitution mutation of humanized CD86.

[0442] In an embodiment, the fusion polypeptide, the second domain comprises a CD86 variant polypeptide, the CD86 variant polypeptide comprising an IgV domain amino acid substitution mutant of CD86 and / or an extracellular domain amino acid substitution mutant of humanized CD86.

[0443] In an embodiment, the fusion polypeptide, the second domain comprises a CD86 variant polypeptide, the CD86 variant polypeptide comprising an IgV domain amino acid substitution mutant of CD86, the mutation site of the IgV domain amino acid substitution mutant of CD86 comprising 1, 2, 3, 4, 5 or more amino acid site mutations selected from the group consisting of A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

[0444] In a fusion polypeptide in an embodiment, the second domain comprises a CD86 variant polypeptide comprising an IgV domain amino acid substitution mutant of CD86 comprising a combination of Q25I / F33L / H90I, Q25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V, Q25V / F33L / H90V, Q25I / F33V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F33L / H90I, A13L / Q25V / F33L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M60R / H90I, Q25V / F33L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F, Q25I / F33A / H90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13F / Q25I / F33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I, and Q25I / F33L / H90M.

[0445] In a fusion polypeptide in an embodiment, the second domain comprises a CD86 variant polypeptide comprising an IgV domain amino acid substitution mutant of CD86 comprising Q25I / F33L / H90I.

[0446] In a fusion polypeptide in an embodiment, the second domain comprises a CD86 variant polypeptide comprising an extracellular domain amino acid substitution mutant of CD86 comprising 1, 2, 3, 4, 5 or more amino acid site mutations selected from the group consisting of A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

[0447] In an embodiment, the CD86 variant polypeptide comprises an extracellular domain amino acid substitution mutant of CD86 comprising a combination selected from the group consisting of: Q25I / F33L / H90I, 25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V, Q25V / F33L / H90V, Q25I / F33V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F33L / H90I, A13L / Q25V / F33L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M60R / H90I, Q25V / F33L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F, Q25I / F33A / H90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13F / Q25I / F33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I, and Q25I / F33L / H90M.

[0448] In an embodiment, the CD86 variant polypeptide comprises an extracellular domain amino acid substitution mutant of CD86 comprising a combination selected from the group consisting of: Q25I / F33L / H90I.

[0449] In an embodiment, the CD86 variant polypeptide comprises an extracellular domain amino acid substitution mutant of CD86 comprising a combination selected from the group consisting of: Q25I / F33L / H90I.

[0450] In an embodiment, the second domain is selected from the group consisting of the amino acid sequences of SEQ ID NO: 2 to SEQ ID NO: 3, SEQ ID NO: 22 to SEQ ID NO: 87.

[0451] In an embodiment, the fusion polypeptide, the second domain comprises a CD80 variant polypeptide, the mutant comprising an amino acid substitution mutation of humanized CD80.

[0452] In an embodiment, the fusion polypeptide, the second domain comprises a CD80 variant polypeptide, the CD80 variant polypeptide comprising an IgV domain amino acid substitution mutant of CD80 and / or an extracellular domain amino acid substitution mutant of humanized CD80.

[0453] In an embodiment, the fusion polypeptide, the first domain is directly or indirectly linked to the second domain.

[0454] In an embodiment, the fusion polypeptide, the first domain heavy chain is directly or indirectly linked to the second domain.

[0455] In an embodiment, the fusion polypeptide, the C-terminus of the first domain heavy chain is directly or indirectly linked to the N-terminus of the second domain.

[0456] In an embodiment, the fusion polypeptide, the N-terminus of the first domain heavy chain is directly or indirectly linked to the C-terminus of the second domain.

[0457] In an embodiment, the fusion polypeptide, the first domain light chain is directly or indirectly linked to the second domain.

[0458] In an embodiment, the fusion polypeptide, the C-terminus of the first domain light chain is directly or indirectly linked to the N-terminus of the second domain.

[0459] In an embodiment, the fusion polypeptide, the N-terminus of the first domain light chain is directly or indirectly linked to the C-terminus of the second domain.

[0460] In an embodiment, the fusion polypeptide, the indirect linkage comprises linkage via a linker.

[0461] In an embodiment, the fusion polypeptide, the linker comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 16-21.

[0462] In an embodiment, the fusion polypeptide, the fusion polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 400-496, SEQ ID NO: 639.

[0463] In an embodiment, the fusion polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 400-441, SEQ ID NOs: 489-493. In an embodiment, the fusion polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 442-452, SEQ ID NOs: 494-496.

[0464] In an embodiment, the fusion polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 453-488.

[0465] In an embodiment, the fusion polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 639.

[0466] In another aspect, the present application provides a fusion polypeptide comprising a first domain and a third domain, the first domain being capable of blocking HHLA2 / KIR3DL3 signaling. The third domain is capable of activating innate immune response.

[0467] In an embodiment, the fusion polypeptide, the first domain is capable of binding to HHLA2.

[0468] In an embodiment, the fusion polypeptide, the first domain comprises an antibody or an antigen binding fragment thereof.

[0469] In an embodiment, the fusion polypeptide, the first domain has the following CDRs or mutations thereof: LCDR1 selected from the group consisting of SEQ ID NOs: 245, 253, 261, LCDR2 selected from the group consisting of SEQ ID NOs: 246, 254, 271, LCDR3 selected from the group consisting of SEQ ID NOs: 247, 255, 271, HCDR1 selected from the group consisting of SEQ ID NOs: 242, 250, 258, 266, 273, 277, HCDR2 selected from the group consisting of SEQ ID NOs: 243, 251, 259, 267, 274, 278, HCDR3 selected from the group consisting of SEQ ID NOs: 244, 252, 260, 268, 275, 279, 296, wherein the mutations are insertions, deletions or substitutions of 3, 2 or 1 amino acids in the amino acid sequence of the CDRs.

[0470] In one embodiment, the first domain has the amino acid sequence of the HCDR1 set out in SEQ ID NO: 242, the amino acid sequence of the HCDR2 set out in SEQ ID NO: 243, the amino acid sequence of the HCDR3 set out in SEQ ID NO: 244, the amino acid sequence of the LCDR1 set out in SEQ ID NO: 245, the amino acid sequence of the LCDR2 set out in SEQ ID NO: 246, and the amino acid sequence of the LCDR3 set out in SEQ ID NO: 247; or the amino acid sequence of the HCDR1 set out in SEQ ID NO: 250, the amino acid sequence of the HCDR2 set out in SEQ ID NO: 251, the amino acid sequence of the HCDR3 set out in SEQ ID NO: 252, the amino acid sequence of the LCDR1 set out in SEQ ID NO: 253, the amino acid sequence of the LCDR2 set out in SEQ ID NO: 254, and the amino acid sequence of the LCDR3 set out in SEQ ID NO: 255; or the amino acid sequence of the HCDR1 set out in SEQ ID NO: 258, the amino acid sequence of the HCDR2 set out in SEQ ID NO: 259, the amino acid sequence of the HCDR3 set out in SEQ ID NO: 260, the amino acid sequence of the LCDR1 set out in SEQ ID NO: 261, the amino acid sequence of the LCDR2 set out in SEQ ID NO: 254, and the amino acid sequence of the LCDR3 set out in SEQ ID NO: 255; or the amino acid sequence of the HCDR1 set out in SEQ ID NO: 266, the amino acid sequence of the HCDR2 set out in SEQ ID NO: 267, the amino acid sequence of the HCDR3 set out in SEQ ID NO: 268, the amino acid sequence of the LCDR1 set out in SEQ ID NO: 261, the amino acid sequence of the LCDR2 set out in SEQ ID NO: 254, and the amino acid sequence of the LCDR3 set out in SEQ ID NO: 271; or the amino acid sequence of the HCDR1 set out in SEQ ID NO: 273, the amino acid sequence of the HCDR2 set out in SEQ ID NO: 274, and the amino acid sequence of the HCDR3 set out in SEQ ID NO: 275; or the amino acid sequence of the HCDR1 set out in SEQ ID NO: 277, the amino acid sequence of the HCDR2 set out in SEQ ID NO: 278, and the amino acid sequence of the HCDR3 set out in SEQ ID NO: 279.or the amino acid sequence of the HCDR1 is set forth in SEQ ID NO:273, the amino acid sequence of the HCDR2 is set forth in SEQ ID NO:274, and the amino acid sequence of the HCDR3 is set forth in SEQ ID NO:296.

[0471] In one embodiment, the first domain comprises a heavy chain variable region (VH) and a light chain variable region (VL) of an antibody. The amino acid sequence of the VH is selected from the group consisting of SEQ ID NO: 280, 282, 284, 286, 288, 290, 292-293, 295, 297, 307, 317, 337, 357, and the amino acid sequence of the VL is selected from the group consisting of SEQ ID NO: 281, 283, 285, 287, 289, 291, 302, 322, 332. Particular VH / VL combinations include, but are not limited to, SEQ ID NO: 280 / 281, 282 / 283, 284 / 285, 286 / 287, 288 / 289, 290 / 291, 297 / 302, 307 / 302, 317 / 322, 317 / 332, 337 / 322, 337 / 332, 357 / 332.

[0472] In another embodiment, the first domain comprises a heavy chain variable region VHH of a single domain antibody, the amino acid sequence of which is selected from the group consisting of SEQ ID NO: 292, 293, 295.

[0473] In a further embodiment, the first domain comprises a complete antibody heavy chain and light chain. The first domain antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 240, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 241; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 248, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 249; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 256, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 257; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 264, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 265; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 368, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 373; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 369, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 373; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 370, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 374; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 370, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 375; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 371, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 374; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 371, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 375; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 372, and the antibody light chain comprises the amino acid sequence of SEQ ID NO: 375.

[0474] In another embodiment, the first domain comprises a complete antibody heavy chain. The first domain antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 272; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 276; or the antibody heavy chain comprises the amino acid sequence of SEQ ID NO: 367.

[0475] In another embodiment, the first domain comprises an antibody or antigen binding fragment thereof selected from RP004263 (disclosed in patent WO2023138579A1) and hz2D7 (disclosed in patent WO2020041300A1).

[0476] In another embodiment, the first domain comprises a heavy chain variable region (VH) of the antibody, wherein the heavy chain variable region comprises HCDR1, HCDR2 and / or HCDR3, and its amino acid sequence is selected from SEQ ID NO:236 and SEQ ID NO:238.

[0477] In another embodiment, the first domain comprises the complete heavy chain of the antibody, and the amino acid sequence of the antibody heavy chain is selected from SEQ ID NO:236 and SEQ ID NO:238.

[0478] In another embodiment, the first domain comprises a light chain variable region (VL) of the antibody, wherein the light chain variable region comprises LCDR1, LCDR2 and / or LCDR3, and its amino acid sequence is selected from SEQ ID NO:237 and SEQ ID NO:239.

[0479] In another embodiment, the first domain comprises the complete light chain of the antibody or an antigen-binding fragment thereof, and the amino acid sequence of the antibody light chain is selected from SEQ ID NO:237 and SEQ ID NO:239.

[0480] In one embodiment of the fusion polypeptide, the antibody of the first domain is selected from the group consisting of: recombinant antibodies, single-domain antibodies, heavy chain antibodies, chimeric antibodies, humanized antibodies, fully human antibodies, bispecific antibodies, trispecific antibodies, antibody-drug conjugates (ADCs), Fc fusion proteins, monoclonal antibodies, or polyclonal antibodies.

[0481] Preferably, the anti-B7-H7 antibody or its antigen-binding fragment described in this invention is selected from one or more of the following groups: Fab, Fab', Fv fragment, F(ab')2, F(ab)2, scFv, di-scFv, VHH, dAb, and sdAb.

[0482] In one embodiment, the fusion polypeptide has a third domain capable of binding to MHCII molecules on antigen-presenting cells.

[0483] In one embodiment, the fusion polypeptide includes a third domain comprising LAG3 or a functionally active fragment thereof, or a variant thereof.

[0484] In one embodiment of the fusion polypeptide, the third domain is selected from the group consisting of: human LAG3 or its functionally active fragments, mouse LAG3 or its functionally active fragments, or the aforementioned LAG3 variants of this application.

[0485] In one embodiment, the fusion polypeptide includes a third domain comprising the extracellular domain of LAG3 or a functionally active fragment thereof.

[0486] In one embodiment, the fusion polypeptide includes, in the third domain, IgD1, IgD2, IgD3 and / or IgD4 of LAG3 or a functionally active fragment thereof.

[0487] In one embodiment, the fusion polypeptide includes, in the third domain, IgD1, IgD1-IgD2, IgD1-IgD2-IgD3, and / or IgD1-IgD2-IgD3-IgD4 of LAG3 or a functionally active fragment thereof.

[0488] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide.

[0489] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising a truncated and / or mutated human LAG3.

[0490] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising a truncated peptide based on the extracellular region of wild-type human LAG3.

[0491] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide, the LAG3 variant polypeptide comprising 0-124 amino acids truncated at the N-terminus of a wild-type human LAG3 extracellular region polypeptide, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acids. 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 5 8, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95 Amino acid sequences of 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124 amino acids;Furthermore, the C-terminus terminates at the following positions on the wild-type LAG3 extracellular polypeptide: amino acid positions 121-167, such as amino acid positions 121, 122-146, 122-167, 123-167, 124-167, 125-167, 126-167, 127-167, 128-167, 129-167, 130-167, 131-167, 132-167, 133-167. 134-167, 135-167, 136-167, 137-167, 138-167, 139-167, 140-167, 141-167, 142-167, 143-167, 144-167, 145-167, 146-167, 147-167, 148-167, 149-167, 150-167, 151-167, 152-167, 153-167, 154-167 The position corresponding to any of the following positions: 155-167, 156-167, 157-167, 158-167, 159-167, 160-167, 161-167, 162-167, 163-167, 164-167, 165-167, 166-167, for example, the C-terminus terminates at the following positions: amino acid positions 121, 122, 123, 124, 125, 126, 127 of the extracellular region polypeptide of wild-type LAG3. The positions corresponding to 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167. In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on a wild-type human LAG3 extracellular region polypeptide with an N-terminus truncated by 0, 5, 21, 37, 45, 60, 71, 74, 79, 81, 84, 89, 94, 99, 104, 109, or 114 amino acids.

[0492] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on a wild-type human LAG3 extracellular region polypeptide with 0, 5, 21, 37, 45, 60, 71, 74, 81, or 99 amino acids truncated at the N-terminus.

[0493] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on a wild-type human LAG3 extracellular region polypeptide with 0, 5, 21, 37, 45, 60, 71, or 74 amino acids truncated at the N-terminus.

[0494] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121-167 at the C-terminus.

[0495] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 122-146 at the C-terminus.

[0496] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167.

[0497] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121, 122, 129, 136, 146, 156, 161, or 167 at the C-terminus.

[0498] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121, 146, 156, 161, or 167 at the C-terminus.

[0499] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 156, 161, or 167 at the C-terminus.

[0500] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an N-terminus truncated by 0, 5, 21, 37, 45, 60, 71, 74, 79, 84, 89, 94, 99, 104, 109, or 114 amino acids based on the wild-type human LAG3 extracellular region polypeptide, and a C-terminus terminating at the following positions of the wild-type LAG3 extracellular region polypeptide: 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 amino acids.

[0501] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising 0, 5, 21, 37, 45, 60, 71, 74, 81, or 99 amino acids truncated at the N-terminus of a wild-type human LAG3 extracellular region polypeptide, and an amino acid sequence terminating at amino acid positions 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 at the C-terminus of the wild-type human LAG3 extracellular region polypeptide.

[0502] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an N-terminal truncation of 0, 5, 21, 37, 45, 60, 71, or 74 amino acids based on the wild-type human LAG3 extracellular region polypeptide, and an C-terminal termination of the wild-type human LAG3 extracellular region polypeptide at amino acid positions 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167.

[0503] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising 125-145 amino acids truncated at the N-terminus of a wild-type human LAG3 extracellular region polypeptide, for example, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, or 145 amino acids; and terminating at the C-terminus of the wild-type LAG3 extracellular region polypeptide at a position corresponding to any of amino acid positions 148-167 of the wild-type LAG3 extracellular region polypeptide, for example, 148-167, 149-167, or 149-167. 67, 150-167, 151-167, 152-167, 153-167, 154-167, 155-167, 156-167, 157-167, 158-167, 159-167, 160-167, 161-167, 162-167, 163-167, 164-167, 165-167, 166 The position corresponding to any of the positions in -167, for example, the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 of the extracellular polypeptide of wild-type LAG3.

[0504] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide, the LAG3 variant polypeptide comprising 0-124 amino acids truncated at the N-terminus of a wild-type human LAG3 extracellular region polypeptide, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 amino acids. 1, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 1 03, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124 amino acids; and the C-terminus terminates at the following positions of the wild-type LAG3 extracellular region polypeptide: amino acid positions 1-121 of the wild-type LAG3 extracellular region polypeptide.For example, 1-121, 2-121, 3-121, 4-121, 5-121, 6-121, 7-121, 8-121, 9-121, 10-121, 11-121, 12-121, 13-121, 14-121, 15-121, 16-121, 17-121, 18-121, 19-121, 20-121, 21-121, 22-121, 23-121, 24-121, 25-121, 26-121, 27-121, 28-121, 29-121, 30-121, 31-121, 32-121 33-121, 34-121, 35-121, 36-121, 37-121, 38-121, 39-121, 40-121, 41-121, 42-121, 43-121, 44-121, 45-121, 46-121, 47-121, 48-121, 49-121, 50-121, 51-121, 52-121, 53-121, 54-121, 55-121, 56-121, 57-121, 58-121, 59-121, 60-121, 61-121, 62-121, 63-121 64-121, 65-121, 66-121, 67-121, 68-121, 69-121, 70-121, 71-121, 72-121, 73-121, 74-121, 75-121, 76-121, 77-121, 78-121, 79-121, 80-121, 81-121, 82-121, 83-121, 84-121, 85-121, 86-121, 87-121, 88-121, 89-121, 90-121, 91-121, 92-121, 93-121, 94-12 1. The position corresponding to any of the following positions: 95-121, 96-121, 97-121, 98-121, 99-121, 100-121, 101-121, 102-121, 103-121, 104-121, 105-121, 106-121, 107-121, 108-121, 109-121, 110-121, 111-121, 112-121, 113-121, 114-121, 115-121, 116-121, 117-121, 118-121, 119-121, or 120-121.For example, the C-terminus terminates at the following positions: amino acid positions 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 6 The positions corresponding to 2, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, or 121.

[0505] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation.

[0506] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, the mutation site including the Arg amino acid at position 110.

[0507] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, the amino acid mutation site including a mutation of the Arg amino acid at position 110 to a Lys amino acid.

[0508] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, the amino acid site comprising the Arg amino acid at position 97.

[0509] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, the amino acid mutation site including a mutation of the Arg amino acid at position 97 to the Glu amino acid.

[0510] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing amino acid site mutations, the amino acid mutation sites including R110, R113, R119, R129, G130, and / or R141.

[0511] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R110 site is mutated to K110.

[0512] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R113 site is mutated to K113.

[0513] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R119 site is mutated to K119.

[0514] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R129 site is mutated to K129.

[0515] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the G130 site is mutated to P130, or A130, or T130, or Y130, or S130.

[0516] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R141 site is mutated to K141.

[0517] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R141 site is mutated to K141 and / or the G130 site is mutated to P130.

[0518] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide that is truncated by 81 amino acids at the N-terminus and terminated at amino acid position 121 at the C-terminus, with mutations introduced at R110, and / or R113, and / or R119 sites.

[0519] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide that is truncated by 99 amino acids at the N-terminus and terminated at amino acid position 146 at the C-terminus, with mutations introduced at R129, and / or G130, and / or R141 sites.

[0520] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide that is truncated by 81 amino acids at the N-terminus and terminated at amino acid position 146 at the C-terminus, with mutations introduced at sites R110, and / or R113, and / or R119, and / or R129, and / or G130, and / or R141.

[0521] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide that, compared to the wild-type LAG3 extracellular domain polypeptide, has at least one characteristic selected from the following:

[0522] (1) The N-terminus is truncated by 74 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166 or 167 of the extracellular region polypeptide of wild-type LAG3; wherein, preferably, the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 of the extracellular region polypeptide of wild-type LAG3;

[0523] (2) The N-terminus is truncated by 74 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166 or 167 of the extracellular region polypeptide of wild-type LAG3; wherein, preferably, the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 of the extracellular region polypeptide of wild-type LAG3;

[0524] (3) The N-terminus is truncated by 5 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0525] (4) The N-terminus is truncated by 5 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0526] (5) The N-terminus is truncated by 21 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0527] (6) The N-terminus is truncated by 21 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0528] (7) The N-terminus is truncated by 37 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0529] (8) The N-terminus is truncated by 37 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0530] (9) The N-terminus is truncated by 45 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0531] (10) The N-terminus is truncated by 45 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0532] (11) The N-terminus is truncated by 60 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0533] (12) The N-terminus is truncated by 60 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0534] (13) The N-terminus is truncated by 71 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0535] (14) The N-terminus is truncated by 71 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0536] (15) The N-terminus is truncated by 79 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0537] (16) The N-terminus is truncated by 84 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0538] (17) The N-terminus is truncated by 89 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0539] (18) The N-terminus is truncated by 94 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0540] (19) The N-terminus is truncated by 99 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 146, 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0541] (20) The N-terminus is truncated by 99 amino acids and the C-terminus is terminated at amino acid position 146, and a mutant LAG3 polypeptide variant is introduced at R129, and / or G130, and / or R141 sites.

[0542] (21) The N-terminus is truncated by 104 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0543] (22) The N-terminus is truncated by 109 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0544] (23) The N-terminus is truncated by 114 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0545] (24) The N-terminus is truncated by 0 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0546] (25) The N-terminus is truncated by 0 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0547] (26) The N-terminus is truncated by 81 amino acids and the C-terminus is terminated at amino acid position 121, and a mutant LAG3 peptide variant is introduced at R110, and / or R113, and / or R119 sites.

[0548] (27) The N-terminus is truncated by 81 amino acids and the C-terminus is terminated at amino acid position 146, and mutated LAG3 peptide variants are introduced at R110, and / or R113, and / or R119, and / or R129, and / or G130, and / or R141 sites.

[0549] In one embodiment of the fusion polypeptide, the third domain comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 5 to SEQ ID NO: 13 and SEQ ID NO: 88 to SEQ ID NO: 227.

[0550] In one embodiment of the fusion polypeptide, the first domain is directly or indirectly connected to the third domain.

[0551] In one embodiment of the fusion polypeptide, the heavy chain of the first domain is directly or indirectly linked to the third domain.

[0552] In one embodiment of the fusion polypeptide, the C-terminus of the heavy chain of the first domain is directly or indirectly connected to the N-terminus of the third domain.

[0553] In one embodiment of the fusion polypeptide, the N-terminus of the heavy chain of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0554] In one embodiment of the fusion polypeptide, the first domain light chain is directly or indirectly connected to the third domain.

[0555] In one embodiment of the fusion polypeptide, the C-terminus of the light chain of the first domain is directly or indirectly connected to the N-terminus of the third domain.

[0556] In one embodiment of the fusion polypeptide, the N-terminus of the light chain of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0557] In one embodiment of the fusion polypeptide, the indirect connection comprises a linker.

[0558] In one embodiment, the linker comprises an amino acid sequence selected from the group shown below: SEQ ID NO: 16-21.

[0559] In one embodiment, the fusion polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 500-547, SEQ ID NO: 583-586.

[0560] On the other hand, this application provides a fusion polypeptide comprising a first domain, a second domain and a third domain, wherein the first domain is capable of blocking HHLA2 / KIR3DL3 signaling; the second domain is capable of binding CD28 and / or CTLA4; and the third domain is capable of activating an innate immune response.

[0561] In one embodiment of the fusion polypeptide, the first domain is capable of binding HHLA2.

[0562] In one embodiment, the fusion polypeptide has a first domain comprising an antibody or an antigen-binding fragment thereof.

[0563] In one embodiment of the fusion polypeptide, the first domain has the following CDRs or mutations thereof: LCDR1 selected from SEQ ID NO:245, 253, 261; LCDR2 selected from SEQ ID NO:246, 254; LCDR3 selected from SEQ ID NO:247, 255, 271; and HCDR1 selected from SEQ ID NO:242, 250, 258, 266, 273, 277; HCDR2 selected from SEQ ID NO:243, 251, 259, 267, 274, 278; and HCDR3 selected from SEQ ID NO:244, 252, 260, 268, 275, 279, 296, wherein the mutation is an insertion, deletion, or substitution of 3, 2, or 1 amino acids in the amino acid sequence of the CDR.

[0564] In one embodiment, the amino acid sequence of HCDR1 in the first domain is shown in SEQ ID NO:242, the amino acid sequence of HCDR2 is shown in SEQ ID NO:243, the amino acid sequence of HCDR3 is shown in SEQ ID NO:244, the amino acid sequence of LCDR1 is shown in SEQ ID NO:245, the amino acid sequence of LCDR2 is shown in SEQ ID NO:246, and the amino acid sequence of LCDR3 is shown in SEQ ID NO:247; or the amino acid sequence of HCDR1 is shown in SEQ ID NO:250, the amino acid sequence of HCDR2 is shown in SEQ ID NO:251, the amino acid sequence of HCDR3 is shown in SEQ ID NO:252, the amino acid sequence of LCDR1 is shown in SEQ ID NO:253, the amino acid sequence of LCDR2 is shown in SEQ ID NO:254, and the amino acid sequence of LCDR3 is shown in SEQ ID NO:255; or the amino acid sequence of HCDR1 is shown in SEQ ID NO:258, the amino acid sequence of HCDR2 is shown in SEQ ID NO:249, and the amino acid sequence of LCDR3 is shown in SEQ ID NO:255. As shown in NO:259, the amino acid sequence of HCDR3 is as shown in SEQ ID NO:260, the amino acid sequence of LCDR1 is as shown in SEQ ID NO:261, the amino acid sequence of LCDR2 is as shown in SEQ ID NO:254, and the amino acid sequence of LCDR3 is as shown in SEQ ID NO:255; or the amino acid sequence of HCDR1 is as shown in SEQ ID NO:266, the amino acid sequence of HCDR2 is as shown in SEQ ID NO:267, the amino acid sequence of HCDR3 is as shown in SEQ ID NO:268, the amino acid sequence of LCDR1 is as shown in SEQ ID NO:261, the amino acid sequence of LCDR2 is as shown in SEQ ID NO:254, and the amino acid sequence of LCDR3 is as shown in SEQ ID NO:271; or the amino acid sequence of HCDR1 is as shown in SEQ ID NO:273, the amino acid sequence of HCDR2 is as shown in SEQ ID NO:274, and the amino acid sequence of HCDR3 is as shown in SEQ ID NO:275; or the amino acid sequence of HCDR1 is as shown in SEQ ID NO:279. As shown in NO:277, the amino acid sequence of HCDR2 is shown in SEQ ID NO:278, and the amino acid sequence of HCDR3 is shown in SEQ ID NO:279.Alternatively, the amino acid sequence of HCDR1 is as shown in SEQ ID NO:273, the amino acid sequence of HCDR2 is as shown in SEQ ID NO:274, and the amino acid sequence of HCDR3 is as shown in SEQ ID NO:296.

[0565] In one embodiment, the first domain includes a heavy chain variable region (VH) and a light chain variable region (VL) of the antibody. The amino acid sequence of VH is selected from SEQ ID NO:280, 282, 284, 286, 288, 290, 292-293, 295, 297, 307, 317, 337, 357, while the amino acid sequence of VL is selected from SEQ ID NO:281, 283, 285, 287, 289, 291, 302, 322, 332. Specific VH / VL combinations include, but are not limited to, SEQ ID NO: 280 / 281, 282 / 283, 284 / 285, 286 / 287, 288 / 289, 290 / 291, 297 / 302, 307 / 302, 317 / 322, 317 / 332, 337 / 322, 337 / 332, and 357 / 332.

[0566] In another embodiment, the first domain comprises the heavy chain variable region VHH of a single-domain antibody, the amino acid sequence of which is selected from SEQ ID NO:292, 293, 295.

[0567] In a further embodiment, the first domain comprises the complete antibody heavy and light chains. The first domain antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 240, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 241; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 248, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 249; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 256, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 257; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 264, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 265; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 368, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 373; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 369, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 373; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 370, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 374; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 241; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 248, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 249; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 256, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 257; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 264, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 265; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 368, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 373; or the antibody heavy The antibody light chain contains the amino acid sequence shown in SEQ ID NO: 375; or the antibody heavy chain contains the amino acid sequence shown in SEQ ID NO: 371, and the antibody light chain contains the amino acid sequence shown in SEQ ID NO: 374; or the antibody heavy chain contains the amino acid sequence shown in SEQ ID NO: 371, and the antibody light chain contains the amino acid sequence shown in SEQ ID NO: 375; or the antibody heavy chain contains the amino acid sequence shown in SEQ ID NO: 372, and the antibody light chain contains the amino acid sequence shown in SEQ ID NO: 375.

[0568] In another embodiment, the first domain comprises the complete antibody heavy chain. The antibody heavy chain of the first domain comprises the amino acid sequence shown in SEQ ID NO: 272; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 276; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 367.

[0569] In another embodiment, the first domain comprises an antibody or an antigen-binding fragment thereof, said antibody or fragment being selected from RP004263 (disclosed in patent WO2023138579A1) and hz2D7 (disclosed in patent WO2020041300A1).

[0570] In another embodiment, the first domain comprises a heavy chain variable region (VH) of the antibody, wherein the heavy chain variable region comprises HCDR1, HCDR2 and / or HCDR3, and its amino acid sequence is selected from SEQ ID NO:236 and SEQ ID NO:238.

[0571] In another embodiment, the first domain comprises the complete heavy chain of the antibody, and the amino acid sequence of the antibody heavy chain is selected from SEQ ID NO:236 and SEQ ID NO:238.

[0572] In another embodiment, the first domain comprises a light chain variable region (VL) of the antibody, wherein the light chain variable region comprises LCDR1, LCDR2 and / or LCDR3, and its amino acid sequence is selected from SEQ ID NO:237 and SEQ ID NO:239.

[0573] In another embodiment, the first domain comprises the complete light chain of the antibody or an antigen-binding fragment thereof, and the amino acid sequence of the antibody light chain is selected from SEQ ID NO:237 and SEQ ID NO:239. In one embodiment of the fusion polypeptide, the antibody of the first domain is selected from the group consisting of: recombinant antibodies, single-domain antibodies, heavy-chain antibodies, chimeric antibodies, humanized antibodies, fully human antibodies, bispecific antibodies, trispecific antibodies, antibody-drug conjugates (ADCs), Fc fusion proteins, monoclonal antibodies, or polyclonal antibodies.

[0574] Preferably, the anti-B7-H7 antibody or its antigen-binding fragment described in this invention is selected from one or more of the following groups: Fab, Fab', Fv fragment, F(ab')2, F(ab)2, scFv, di-scFv, VHH, dAb, and sdAb.

[0575] In one embodiment of the fusion polypeptide, the second domain comprises CD86 or CD80 or a functionally active fragment thereof, or / and a variant of CD86 or CD80.

[0576] In one embodiment of the fusion polypeptide, the second domain is selected from the group consisting of CD86 or CD80 derived from humans or mice, or functionally active fragments thereof.

[0577] In one embodiment of the fusion polypeptide, the second domain comprises the IgV domain of CD86 or CD80 or a functionally active fragment thereof.

[0578] In one embodiment of the fusion polypeptide, the second domain comprises the extracellular domain of CD86 or CD80 or a functionally active fragment thereof.

[0579] In one embodiment, the fusion polypeptide includes a second domain comprising a CD86 variant polypeptide, the mutant comprising an amino acid substitution mutation of humanized CD86.

[0580] In one embodiment of the fusion polypeptide, the second domain comprises a CD86 variant polypeptide, the CD86 variant polypeptide comprising an IgV domain amino acid substitution mutant of CD86 and / or an extracellular domain amino acid substitution mutant of humanized CD86.

[0581] In one embodiment of the fusion polypeptide, the second domain comprises a CD86 variant polypeptide, the CD86 variant polypeptide comprising an IgV domain amino acid substitution mutant of CD86, the mutation site of the CD86 IgV domain amino acid substitution mutant comprising one, two, three, four, five or more amino acid site mutations selected from the group consisting of: A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

[0582] In one embodiment, the fusion polypeptide includes a second domain comprising a CD86 variant polypeptide comprising an IgV domain amino acid substitution mutant of CD86, the amino acid substitution mutant comprising a combination of the following: Q25I / F33L / H90I, Q25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V , Q25V / F33L / H90V, Q25I / F33V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F3 3L / H90I, A13L / Q25V / F33L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M 60R / H90I, Q25V / F33L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F , Q25I / F33A / H90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13 F / Q25I / F33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H 90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I and Q25I / F33L / H90M.

[0583] In one embodiment of the fusion polypeptide, the second domain comprises a CD86 variant polypeptide, the CD86 variant polypeptide comprising the IgV domain amino acid substitution mutant Q25I / F33L / H90I of CD86.

[0584] In one embodiment, the fusion polypeptide includes a second domain comprising a CD86 variant polypeptide comprising an extracellular domain amino acid substitution mutant of CD86, wherein the extracellular domain amino acid substitution mutant of CD86 comprises one, two, three, four, five, or more amino acid site mutations selected from the group consisting of: A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

[0585] In one embodiment, a CD86 variant peptide comprises an extracellular domain amino acid substitution mutant of CD86, the amino acid substitution mutant comprising combinations shown below: Q25I / F33L / H90I, Q25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V, Q25V / F33L / H90V, Q25I / F33V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F33L / H90I, A 13L / Q25V / F33L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M60R / H90 I. Q25V / F33L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F, Q25I / F33A / H90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13F / Q 25I / F33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I and Q25I / F33L / H90M.

[0586] In one embodiment, a CD86 variant peptide comprises an extracellular domain amino acid substitution mutant of CD86, the amino acid substitution mutant comprising the combination shown below: Q25I / F33L / H90I.

[0587] In one embodiment, a CD86 variant polypeptide comprises an amino acid sequence selected from SEQ ID NO: 22 to SEQ ID NO: 87.

[0588] In one embodiment of the fusion polypeptide, the second domain is selected from the amino acid sequences shown in the group consisting of SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 22 to SEQ ID NO: 87.

[0589] In one embodiment, the fusion polypeptide includes a second domain comprising a CD80 variant polypeptide, the mutant comprising an amino acid substitution mutation of humanized CD80.

[0590] In one embodiment of the fusion polypeptide, the second domain comprises a CD80 variant polypeptide, the CD80 variant polypeptide comprising an IgV domain amino acid substitution mutant of CD80 and / or an extracellular domain amino acid substitution mutant of humanized CD80.

[0591] In one embodiment, the fusion polypeptide has a third domain capable of binding to MHCII molecules on antigen-presenting cells.

[0592] In one embodiment, the fusion polypeptide includes a third domain comprising LAG3 or a functionally active fragment thereof, or a variant thereof.

[0593] In one embodiment of the fusion polypeptide, the third domain is selected from the group consisting of: human LAG3 or its functionally active fragments, mouse LAG3 or its functionally active fragments, or the aforementioned LAG3 variants of this application.

[0594] In one embodiment, the fusion polypeptide includes a third domain comprising the extracellular domain of LAG3 or a functionally active fragment thereof.

[0595] In one embodiment, the fusion polypeptide includes, in the third domain, IgD1, IgD2, IgD3 and / or IgD4 of LAG3 or a functionally active fragment thereof.

[0596] In one embodiment, the fusion polypeptide includes, in the third domain, IgD1, IgD1-IgD2, IgD1-IgD2-IgD3, and / or IgD1-IgD2-IgD3-IgD4 of LAG3 or a functionally active fragment thereof.

[0597] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide.

[0598] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising a truncated and / or mutated human LAG3.

[0599] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising a truncated peptide based on the extracellular region of wild-type human LAG3.

[0600] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide, the LAG3 variant polypeptide comprising 0-124 amino acids truncated at the N-terminus of a wild-type human LAG3 extracellular region polypeptide, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acids. 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 5 8, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95 Amino acid sequences of 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124 amino acids;Furthermore, the C-terminus terminates at the following positions on the wild-type LAG3 extracellular polypeptide: amino acid positions 121-167, such as amino acid positions 121, 122-146, 122-167, 123-167, 124-167, 125-167, 126-167, 127-167, 128-167, 129-167, 130-167, 131-167, 132-167, 133-167. 134-167, 135-167, 136-167, 137-167, 138-167, 139-167, 140-167, 141-167, 142-167, 143-167, 144-167, 145-167, 146-167, 147-167, 148-167, 149-167, 150-167, 151-167, 152-167, 153-167, 154-167 The position corresponding to any of the following positions: 155-167, 156-167, 157-167, 158-167, 159-167, 160-167, 161-167, 162-167, 163-167, 164-167, 165-167, 166-167, for example, the C-terminus terminates at the following positions: amino acid positions 121, 122, 123, 124, 125, 126, 127 of the extracellular region polypeptide of wild-type LAG3. The positions corresponding to 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167. In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on a wild-type human LAG3 extracellular region polypeptide with an N-terminus truncated by 0, 5, 21, 37, 45, 60, 71, 74, 79, 81, 84, 89, 94, 99, 104, 109, or 114 amino acids.

[0601] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on a wild-type human LAG3 extracellular region polypeptide with 0, 5, 21, 37, 45, 60, 71, 74, 81, or 99 amino acids truncated at the N-terminus.

[0602] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on a wild-type human LAG3 extracellular region polypeptide with 0, 5, 21, 37, 45, 60, 71, or 74 amino acids truncated at the N-terminus.

[0603] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121-167 at the C-terminus.

[0604] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 122-146 at the C-terminus.

[0605] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167.

[0606] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121, 122, 129, 136, 146, 156, 161, or 167 at the C-terminus.

[0607] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121, 146, 156, 161, or 167 at the C-terminus.

[0608] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 156, 161, or 167 at the C-terminus.

[0609] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an N-terminus truncated by 0, 5, 21, 37, 45, 60, 71, 74, 79, 84, 89, 94, 99, 104, 109, or 114 amino acids based on the wild-type human LAG3 extracellular region polypeptide, and a C-terminus terminating at the following positions of the wild-type LAG3 extracellular region polypeptide: 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 amino acids.

[0610] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising 0, 5, 21, 37, 45, 60, 71, 74, 81, or 99 amino acids truncated at the N-terminus of a wild-type human LAG3 extracellular region polypeptide, and an amino acid sequence terminating at amino acid positions 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 at the C-terminus of the wild-type human LAG3 extracellular region polypeptide.

[0611] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an N-terminal truncation of 0, 5, 21, 37, 45, 60, 71, or 74 amino acids based on the wild-type human LAG3 extracellular region polypeptide, and an C-terminal termination of the wild-type human LAG3 extracellular region polypeptide at amino acid positions 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167.

[0612] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising 125-145 amino acids truncated at the N-terminus of a wild-type human LAG3 extracellular region polypeptide, for example, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, or 145 amino acids; and terminating at the C-terminus of the wild-type LAG3 extracellular region polypeptide at a position corresponding to any of amino acid positions 148-167 of the wild-type LAG3 extracellular region polypeptide, for example, 148-167, 149-167, or 149-167. 67, 150-167, 151-167, 152-167, 153-167, 154-167, 155-167, 156-167, 157-167, 158-167, 159-167, 160-167, 161-167, 162-167, 163-167, 164-167, 165-167, 166 The position corresponding to any of the positions in -167, for example, the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 of the extracellular polypeptide of wild-type LAG3.

[0613] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide, the LAG3 variant polypeptide comprising 0-124 amino acids truncated at the N-terminus of a wild-type human LAG3 extracellular region polypeptide, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 amino acids. 1, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 1 03, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124 amino acids; and the C-terminus terminates at the following positions of the wild-type LAG3 extracellular region polypeptide: amino acid positions 1-121 of the wild-type LAG3 extracellular region polypeptide.For example, 1-121, 2-121, 3-121, 4-121, 5-121, 6-121, 7-121, 8-121, 9-121, 10-121, 11-121, 12-121, 13-121, 14-121, 15-121, 16-121, 17-121, 18-121, 19-121, 20-121, 21-121, 22-121, 23-121, 24-121, 25-121, 26-121, 27-121, 28-121, 29-121, 30-121, 31-121, 32-121 33-121, 34-121, 35-121, 36-121, 37-121, 38-121, 39-121, 40-121, 41-121, 42-121, 43-121, 44-121, 45-121, 46-121, 47-121, 48-121, 49-121, 50-121, 51-121, 52-121, 53-121, 54-121, 55-121, 56-121, 57-121, 58-121, 59-121, 60-121, 61-121, 62-121, 63-121 64-121, 65-121, 66-121, 67-121, 68-121, 69-121, 70-121, 71-121, 72-121, 73-121, 74-121, 75-121, 76-121, 77-121, 78-121, 79-121, 80-121, 81-121, 82-121, 83-121, 84-121, 85-121, 86-121, 87-121, 88-121, 89-121, 90-121, 91-121, 92-121, 93-121, 94-12 1. The position corresponding to any of the following positions: 95-121, 96-121, 97-121, 98-121, 99-121, 100-121, 101-121, 102-121, 103-121, 104-121, 105-121, 106-121, 107-121, 108-121, 109-121, 110-121, 111-121, 112-121, 113-121, 114-121, 115-121, 116-121, 117-121, 118-121, 119-121, or 120-121.For example, the C-terminus terminates at the following positions: amino acid positions 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 6 The positions corresponding to 2, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, or 121.

[0614] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation.

[0615] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, the mutation site including the Arg amino acid at position 110.

[0616] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, the amino acid mutation site including a mutation of the Arg amino acid at position 110 to a Lys amino acid.

[0617] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, the amino acid site comprising the Arg amino acid at position 97.

[0618] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, the amino acid mutation site including a mutation of the Arg amino acid at position 97 to the Glu amino acid.

[0619] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing amino acid site mutations, the amino acid mutation sites including R110, R113, R119, R129, G130, and / or R141.

[0620] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R110 site is mutated to K110.

[0621] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R113 site is mutated to K113.

[0622] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R119 site is mutated to K119.

[0623] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R129 site is mutated to K129.

[0624] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the G130 site is mutated to P130, or A130, or T130, or Y130, or S130.

[0625] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R141 site is mutated to K141.

[0626] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R141 site is mutated to K141 and / or the G130 site is mutated to P130.

[0627] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide that is truncated by 81 amino acids at the N-terminus and terminated at amino acid position 121 at the C-terminus, with mutations introduced at sites R110, and / or R113, and / or R119.

[0628] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide that is truncated by 99 amino acids at the N-terminus and terminated at amino acid position 146 at the C-terminus, with mutations introduced at sites R129, and / or G130, and / or R141.

[0629] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide that is truncated by 81 amino acids at the N-terminus and terminated at amino acid position 146 at the C-terminus, with mutations introduced at sites R110, and / or R113, and / or R119, and / or R129, and / or G130, and / or R141.

[0630] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide that, compared to the wild-type LAG3 extracellular domain polypeptide, has at least one characteristic selected from the following:

[0631] (1) The N-terminus is truncated by 74 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166 or 167 of the extracellular region polypeptide of wild-type LAG3; wherein, preferably, the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 of the extracellular region polypeptide of wild-type LAG3;

[0632] (2) The N-terminus is truncated by 74 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166 or 167 of the extracellular region polypeptide of wild-type LAG3; wherein, preferably, the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 of the extracellular region polypeptide of wild-type LAG3;

[0633] (3) The N-terminus is truncated by 5 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0634] (4) The N-terminus is truncated by 5 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0635] (5) The N-terminus is truncated by 21 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0636] (6) The N-terminus is truncated by 21 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0637] (7) The N-terminus is truncated by 37 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0638] (8) The N-terminus is truncated by 37 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0639] (9) The N-terminus is truncated by 45 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0640] (10) The N-terminus is truncated by 45 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0641] (11) The N-terminus is truncated by 60 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0642] (12) The N-terminus is truncated by 60 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0643] (13) The N-terminus is truncated by 71 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0644] (14) The N-terminus is truncated by 71 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0645] (15) The N-terminus is truncated by 79 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0646] (16) The N-terminus is truncated by 84 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0647] (17) The N-terminus is truncated by 89 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0648] (18) The N-terminus is truncated by 94 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0649] (19) The N-terminus is truncated by 99 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 146, 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0650] (20) The N-terminus is truncated by 99 amino acids and the C-terminus is terminated at amino acid position 146, and a mutant LAG3 polypeptide variant is introduced at R129, and / or G130, and / or R141 sites.

[0651] (21) The N-terminus is truncated by 104 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0652] (22) The N-terminus is truncated by 109 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0653] (23) The N-terminus is truncated by 114 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0654] (24) The N-terminus is truncated by 0 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0655] (25) The N-terminus is truncated by 0 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0656] (26) The N-terminus is truncated by 81 amino acids and the C-terminus is terminated at amino acid position 121, and a mutant LAG3 peptide variant is introduced at R110, and / or R113, and / or R119 sites.

[0657] (27) The N-terminus is truncated by 81 amino acids and the C-terminus is terminated at amino acid position 146, and mutated LAG3 peptide variants are introduced at R110, and / or R113, and / or R119, and / or R129, and / or G130, and / or R141 sites.

[0658] In one embodiment of the fusion polypeptide, the third domain comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 5 to SEQ ID NO: 13 and SEQ ID NO: 88 to SEQ ID NO: 227.

[0659] In one embodiment, the fusion polypeptide has the first and second domains directly or indirectly linked.

[0660] In one embodiment of the fusion polypeptide, the heavy chain of the first domain is directly or indirectly linked to the second domain.

[0661] In one embodiment of the fusion polypeptide, the C-terminus of the heavy chain of the first domain is directly or indirectly connected to the N-terminus of the second domain.

[0662] In one embodiment of the fusion polypeptide, the N-terminus of the heavy chain of the first domain is directly or indirectly connected to the C-terminus of the second domain.

[0663] In one embodiment of the fusion polypeptide, the light chain of the first domain is directly or indirectly connected to the second domain.

[0664] In one embodiment of the fusion polypeptide, the C-terminus of the light chain of the first domain is directly or indirectly connected to the N-terminus of the second domain.

[0665] In one embodiment of the fusion polypeptide, the N-terminus of the light chain of the first domain is directly or indirectly connected to the C-terminus of the second domain.

[0666] In one embodiment of the fusion polypeptide, the first domain and the third domain are directly or indirectly connected.

[0667] In one embodiment of the fusion polypeptide, the heavy chain of the first domain is directly or indirectly linked to the third domain.

[0668] In one embodiment of the fusion polypeptide, the C-terminus of the heavy chain of the first domain is directly or indirectly connected to the N-terminus of the third domain.

[0669] In one embodiment of the fusion polypeptide, the N-terminus of the heavy chain of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0670] In one embodiment of the fusion polypeptide, the first domain light chain is directly or indirectly connected to the third domain.

[0671] In one embodiment of the fusion polypeptide, the C-terminus of the light chain of the first domain is directly or indirectly connected to the N-terminus of the third domain.

[0672] In one embodiment of the fusion polypeptide, the N-terminus of the light chain of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0673] In one embodiment, the fusion polypeptide has the second and third domains directly or indirectly connected.

[0674] In one embodiment of the fusion polypeptide, the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0675] In one embodiment of the fusion polypeptide, the N-terminus of the second structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

[0676] In one embodiment of the fusion polypeptide, the first domain is directly or indirectly connected to the second domain, and the second domain is directly or indirectly connected to the third domain.

[0677] In one embodiment of the fusion polypeptide, the C-terminus of the first domain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0678] In one embodiment of the fusion polypeptide, the C-terminus of the heavy chain of the first domain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0679] In one embodiment of the fusion polypeptide, the C-terminus of the light chain of the first domain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0680] In one embodiment of the fusion polypeptide, the N-terminus of the first structural domain is directly or indirectly connected to the C-terminus of the second structural domain, and the N-terminus of the second structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

[0681] In one embodiment of the fusion polypeptide, the N-terminus of the heavy chain of the first domain is directly or indirectly connected to the C-terminus of the second domain, and the N-terminus of the second domain is directly or indirectly connected to the C-terminus of the third domain.

[0682] In one embodiment of the fusion polypeptide, the N-terminus of the light chain of the first domain is directly or indirectly connected to the C-terminus of the second domain, and the N-terminus of the second domain is directly or indirectly connected to the C-terminus of the third domain.

[0683] In one embodiment of the fusion polypeptide, the first domain is directly or indirectly connected to the third domain, and the third domain is directly or indirectly connected to the second domain.

[0684] In one embodiment of the fusion polypeptide, the C-terminus of the first structural domain is directly or indirectly connected to the N-terminus of the third structural domain, and the C-terminus of the third structural domain is directly or indirectly connected to the N-terminus of the second structural domain.

[0685] In one embodiment of the fusion polypeptide, the C-terminus of the heavy chain of the first domain is directly or indirectly connected to the N-terminus of the third domain, and the C-terminus of the third domain is directly or indirectly connected to the N-terminus of the second domain.

[0686] In one embodiment of the fusion polypeptide, the C-terminus of the light chain of the first domain is directly or indirectly connected to the N-terminus of the third domain, and the C-terminus of the third domain is directly or indirectly connected to the N-terminus of the second domain.

[0687] In one embodiment of the fusion polypeptide, the N-terminus of the first structural domain is directly or indirectly connected to the C-terminus of the third structural domain, and the N-terminus of the third structural domain is directly or indirectly connected to the C-terminus of the second structural domain.

[0688] In one embodiment of the fusion polypeptide, the N-terminus of the heavy chain of the first domain is directly or indirectly connected to the C-terminus of the third domain, and the N-terminus of the third domain is directly or indirectly connected to the C-terminus of the second domain.

[0689] In one embodiment of the fusion polypeptide, the N-terminus of the light chain of the first domain is directly or indirectly connected to the C-terminus of the third domain, and the N-terminus of the third domain is directly or indirectly connected to the C-terminus of the second domain.

[0690] In one embodiment of the fusion polypeptide, the first domain is directly or indirectly connected to the second domain, and the first domain is directly or indirectly connected to the third domain.

[0691] In one embodiment of the fusion polypeptide, the C-terminus of the first domain is directly or indirectly connected to the N-terminus of the second domain, and the N-terminus of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0692] In one embodiment of the fusion polypeptide, the C-terminus of the heavy chain of the first domain is directly or indirectly connected to the N-terminus of the second domain, and the N-terminus of the heavy chain of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0693] In one embodiment of the fusion polypeptide, the C-terminus of the light chain of the first domain is directly or indirectly connected to the N-terminus of the second domain, and the N-terminus of the light chain of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0694] In one embodiment of the fusion polypeptide, the C-terminus of the heavy chain of the first domain is directly or indirectly connected to the N-terminus of the second domain, and the N-terminus of the light chain of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0695] In one embodiment of the fusion polypeptide, the C-terminus of the light chain of the first domain is directly or indirectly connected to the N-terminus of the second domain, and the N-terminus of the heavy chain of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0696] In one embodiment of the fusion polypeptide, the N-terminus of the first structural domain is directly or indirectly connected to the C-terminus of the second structural domain, and the C-terminus of the first structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

[0697] In one embodiment of the fusion polypeptide, the N-terminus of the heavy chain of the first domain is directly or indirectly connected to the C-terminus of the second domain, and the C-terminus of the heavy chain of the first domain is directly or indirectly connected to the N-terminus of the third domain.

[0698] In one embodiment of the fusion polypeptide, the N-terminus of the light chain of the first domain is directly or indirectly connected to the C-terminus of the second domain, and the C-terminus of the light chain of the first domain is directly or indirectly connected to the N-terminus of the third domain.

[0699] In one embodiment of the fusion polypeptide, the N-terminus of the heavy chain of the first domain is directly or indirectly connected to the C-terminus of the second domain, and the C-terminus of the light chain of the first domain is directly or indirectly connected to the N-terminus of the third domain.

[0700] In one embodiment of the fusion polypeptide, the N-terminus of the light chain of the first domain is directly or indirectly connected to the C-terminus of the second domain, and the C-terminus of the heavy chain of the first domain is directly or indirectly connected to the N-terminus of the third domain.

[0701] In one embodiment of the fusion polypeptide, the indirect connection comprises a linker.

[0702] In one embodiment, the linker comprises an amino acid sequence selected from the group shown below: SEQ ID NO: 16-21.

[0703] In one embodiment, the fusion polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 412-441, SEQ ID NO: 448-488, SEQ ID NO: 500-519, SEQ ID NO: 528-582, and SEQ ID NO: 774.

[0704] On the other hand, this application provides a fusion polypeptide comprising a first domain, a second domain and a fourth domain, wherein the first domain is capable of blocking HHLA2 / KIR3DL3 signaling, the second domain is capable of binding CD28 and / or CTLA4, and the fourth domain is capable of binding to T cells and / or NK cells and / or tumor cells.

[0705] In one embodiment of the fusion polypeptide, the first domain is capable of binding HHLA2.

[0706] In one embodiment, the fusion polypeptide has a first domain comprising an antibody or an antigen-binding fragment thereof.

[0707] In one embodiment of the fusion polypeptide, the first domain has the following CDRs or mutations thereof: LCDR1 selected from SEQ ID NO:245, 253, 261; LCDR2 selected from SEQ ID NO:246, 254; LCDR3 selected from SEQ ID NO:247, 255, 271; and HCDR1 selected from SEQ ID NO:242, 250, 258, 266, 273, 277; HCDR2 selected from SEQ ID NO:243, 251, 259, 267, 274, 278; and HCDR3 selected from SEQ ID NO:244, 252, 260, 268, 275, 279, 296, wherein the mutation is an insertion, deletion, or substitution of 3, 2, or 1 amino acids in the amino acid sequence of the CDR.

[0708] In one embodiment, the amino acid sequence of HCDR1 in the first domain is shown in SEQ ID NO:242, the amino acid sequence of HCDR2 is shown in SEQ ID NO:243, the amino acid sequence of HCDR3 is shown in SEQ ID NO:244, the amino acid sequence of LCDR1 is shown in SEQ ID NO:245, the amino acid sequence of LCDR2 is shown in SEQ ID NO:246, and the amino acid sequence of LCDR3 is shown in SEQ ID NO:247; or the amino acid sequence of HCDR1 is shown in SEQ ID NO:250, the amino acid sequence of HCDR2 is shown in SEQ ID NO:251, the amino acid sequence of HCDR3 is shown in SEQ ID NO:252, the amino acid sequence of LCDR1 is shown in SEQ ID NO:253, the amino acid sequence of LCDR2 is shown in SEQ ID NO:254, and the amino acid sequence of LCDR3 is shown in SEQ ID NO:255; or the amino acid sequence of HCDR1 is shown in SEQ ID NO:258, the amino acid sequence of HCDR2 is shown in SEQ ID NO:249, and the amino acid sequence of LCDR3 is shown in SEQ ID NO:255. As shown in NO:259, the amino acid sequence of HCDR3 is as shown in SEQ ID NO:260, the amino acid sequence of LCDR1 is as shown in SEQ ID NO:261, the amino acid sequence of LCDR2 is as shown in SEQ ID NO:254, and the amino acid sequence of LCDR3 is as shown in SEQ ID NO:255; or the amino acid sequence of HCDR1 is as shown in SEQ ID NO:266, the amino acid sequence of HCDR2 is as shown in SEQ ID NO:267, the amino acid sequence of HCDR3 is as shown in SEQ ID NO:268, the amino acid sequence of LCDR1 is as shown in SEQ ID NO:261, the amino acid sequence of LCDR2 is as shown in SEQ ID NO:254, and the amino acid sequence of LCDR3 is as shown in SEQ ID NO:271; or the amino acid sequence of HCDR1 is as shown in SEQ ID NO:273, the amino acid sequence of HCDR2 is as shown in SEQ ID NO:274, and the amino acid sequence of HCDR3 is as shown in SEQ ID NO:275; or the amino acid sequence of HCDR1 is as shown in SEQ ID NO:279. As shown in NO:277, the amino acid sequence of HCDR2 is shown in SEQ ID NO:278, and the amino acid sequence of HCDR3 is shown in SEQ ID NO:279.Alternatively, the amino acid sequence of HCDR1 is as shown in SEQ ID NO:273, the amino acid sequence of HCDR2 is as shown in SEQ ID NO:274, and the amino acid sequence of HCDR3 is as shown in SEQ ID NO:296.

[0709] In one embodiment, the first domain includes a heavy chain variable region (VH) and a light chain variable region (VL) of the antibody. The amino acid sequence of VH is selected from SEQ ID NO:280, 282, 284, 286, 288, 290, 292-293, 295, 297, 307, 317, 337, 357, while the amino acid sequence of VL is selected from SEQ ID NO:281, 283, 285, 287, 289, 291, 302, 322, 332. Specific VH / VL combinations include, but are not limited to, SEQ ID NO: 280 / 281, 282 / 283, 284 / 285, 286 / 287, 288 / 289, 290 / 291, 297 / 302, 307 / 302, 317 / 322, 317 / 332, 337 / 322, 337 / 332, and 357 / 332.

[0710] In another embodiment, the first domain comprises the heavy chain variable region VHH of a single-domain antibody, the amino acid sequence of which is selected from SEQ ID NO:292, 293, 295.

[0711] In a further embodiment, the first domain comprises the complete antibody heavy and light chains. The first domain antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 240, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 241; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 248, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 249; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 256, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 257; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 264, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 265; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 368, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 373; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 369, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 373; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 370, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 374; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 241; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 248, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 249; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 256, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 257; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 264, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 265; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 368, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 373; or the antibody heavy The antibody light chain contains the amino acid sequence shown in SEQ ID NO: 375; or the antibody heavy chain contains the amino acid sequence shown in SEQ ID NO: 371, and the antibody light chain contains the amino acid sequence shown in SEQ ID NO: 374; or the antibody heavy chain contains the amino acid sequence shown in SEQ ID NO: 371, and the antibody light chain contains the amino acid sequence shown in SEQ ID NO: 375; or the antibody heavy chain contains the amino acid sequence shown in SEQ ID NO: 372, and the antibody light chain contains the amino acid sequence shown in SEQ ID NO: 375.

[0712] In another embodiment, the first domain comprises the complete antibody heavy chain. The antibody heavy chain of the first domain comprises the amino acid sequence shown in SEQ ID NO: 272; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 276; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 367.

[0713] In another embodiment, the first domain comprises an antibody or an antigen-binding fragment thereof, said antibody or fragment being selected from RP004263 (disclosed in patent WO2023138579A1) and hz2D7 (disclosed in patent WO2020041300A1).

[0714] In another embodiment, the first domain comprises a heavy chain variable region (VH) of the antibody, wherein the heavy chain variable region comprises HCDR1, HCDR2 and / or HCDR3, and its amino acid sequence is selected from SEQ ID NO:236 and SEQ ID NO:238.

[0715] In another embodiment, the first domain comprises the complete heavy chain of the antibody, and the amino acid sequence of the antibody heavy chain is selected from SEQ ID NO:236 and SEQ ID NO:238.

[0716] In another embodiment, the first domain comprises a light chain variable region (VL) of the antibody, wherein the light chain variable region comprises LCDR1, LCDR2 and / or LCDR3, and its amino acid sequence is selected from SEQ ID NO:237 and SEQ ID NO:239.

[0717] In another embodiment, the first domain comprises the complete light chain of the antibody or an antigen-binding fragment thereof, and the amino acid sequence of the antibody light chain is selected from SEQ ID NO:237 and SEQ ID NO:239. In one embodiment of the fusion polypeptide, the antibody of the first domain is selected from the group consisting of: recombinant antibodies, single-domain antibodies, heavy-chain antibodies, chimeric antibodies, humanized antibodies, fully human antibodies, bispecific antibodies, trispecific antibodies, antibody-drug conjugates (ADCs), Fc fusion proteins, monoclonal antibodies, or polyclonal antibodies.

[0718] Preferably, the anti-B7-H7 antibody or its antigen-binding fragment described in this invention is selected from one or more of the following groups: Fab, Fab', Fv fragment, F(ab')2, F(ab)2, scFv, di-scFv, VHH, dAb, and sdAb.

[0719] In one embodiment of the fusion polypeptide, the first domain comprises a single-chain immunoglobulin domain.

[0720] For example, the single-chain immunoglobulin IgG antibody comprises one or more selected from human IgG1, human IgG2, human IgG3, human IgG4, mouse IgG1, mouse IgG2a, mouse IgG2b and mouse IgG3.

[0721] For example, the first domain includes the Fc domain of a single-chain immunoglobulin IgG antibody, wherein the Fc domain of the single-chain immunoglobulin IgG antibody includes a human IgG1 Fc domain, a human IgG2 Fc domain, a human IgG3 Fc domain, a human IgG4 Fc domain, a mouse IgG1 Fc domain, a mouse IgG2a Fc domain, a mouse IgG2b Fc domain, or a mouse IgG3 Fc domain.

[0722] For example, the first domain includes the Fc domain of single-chain human immunoglobulin IgG1 and has an L234A / L235A mutation.

[0723] In one embodiment, the fusion polypeptide has a first domain single-chain immunoglobulin Fc fragment containing CH2 and / or CH3 sequences.

[0724] In one embodiment, the fusion polypeptide, the single-chain immunoglobulin Fc fragment, comprises CH2 and / or CH3 sequences. Alternatively, the first structure does not include a CH1 domain.

[0725] In one embodiment of the fusion polypeptide, the first domain comprises the Fc domain of single-chain human immunoglobulin IgG1, has an L234A / L235A mutation, and has the necessary mutations in the knobs-into-holes (KiH) pairing, for example: T366 on the CH3 domain of the Knob structure is replaced by a relatively large amino acid residue, such as tyrosine (Y) or tryptophan (W); or, T366 on the CH3 domain of the Hole structure is replaced by serine (S), L368 is replaced by a relatively small amino acid residue, such as alanine (A), and Y407 is replaced by a relatively small amino acid residue, such as threonine (T), alanine (A), or valine (V).

[0726] In one embodiment of the fusion polypeptide, the second domain comprises CD86 or CD80 or a functionally active fragment thereof, or / and a variant of CD86 or CD80.

[0727] In one embodiment of the fusion polypeptide, the second domain is selected from the group consisting of CD86 or CD80 derived from humans or mice, or functionally active fragments thereof.

[0728] In one embodiment of the fusion polypeptide, the second domain comprises the IgV domain of CD86 or CD80 or a functionally active fragment thereof.

[0729] In one embodiment of the fusion polypeptide, the second domain comprises the extracellular domain of CD86 or CD80 or a functionally active fragment thereof.

[0730] In one embodiment, the fusion polypeptide includes a second domain comprising a CD86 variant polypeptide, the mutant comprising an amino acid substitution mutation of humanized CD86.

[0731] In one embodiment of the fusion polypeptide, the second domain comprises a CD86 variant polypeptide, the CD86 variant polypeptide comprising an IgV domain amino acid substitution mutant of CD86 and / or an extracellular domain amino acid substitution mutant of humanized CD86.

[0732] In one embodiment of the fusion polypeptide, the second domain comprises a CD86 variant polypeptide, the CD86 variant polypeptide comprising an IgV domain amino acid substitution mutant of CD86, the mutation site of the CD86 IgV domain amino acid substitution mutant comprising one, two, three, four, five or more amino acid site mutations selected from the group consisting of: A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

[0733] In one embodiment, the fusion polypeptide includes a second domain comprising a CD86 variant polypeptide comprising an IgV domain amino acid substitution mutant of CD86, the amino acid substitution mutant comprising a combination of the following: Q25I / F33L / H90I, Q25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V , Q25V / F33L / H90V, Q25I / F33V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F3 3L / H90I, A13L / Q25V / F33L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M 60R / H90I, Q25V / F33L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F , Q25I / F33A / H90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13 F / Q25I / F33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H 90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I and Q25I / F33L / H90M.

[0734] In one embodiment of the fusion polypeptide, the second domain comprises a CD86 variant polypeptide, the CD86 variant polypeptide comprising the IgV domain amino acid substitution mutant Q25I / F33L / H90I of CD86.

[0735] In one embodiment, the fusion polypeptide includes a second domain comprising a CD86 variant polypeptide comprising an extracellular domain amino acid substitution mutant of CD86, wherein the extracellular domain amino acid substitution mutant of CD86 comprises one, two, three, four, five, or more amino acid site mutations selected from the group consisting of: A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

[0736] In one embodiment, a CD86 variant peptide comprises an extracellular domain amino acid substitution mutant of CD86, the amino acid substitution mutant comprising combinations shown below: Q25I / F33L / H90I, Q25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V, Q25V / F33L / H90V, Q25I / F33V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F33L / H90I, A 13L / Q25V / F33L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M60R / H90 I. Q25V / F33L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F, Q25I / F33A / H90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13F / Q 25I / F33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I and Q25I / F33L / H90M.

[0737] In one embodiment, a CD86 variant peptide comprises an extracellular domain amino acid substitution mutant of CD86, the amino acid substitution mutant comprising the combination shown below: Q25I / F33L / H90I.

[0738] In one embodiment, a CD86 variant polypeptide comprises an amino acid sequence selected from SEQ ID NO: 22 to SEQ ID NO: 87.

[0739] In one embodiment of the fusion polypeptide, the second domain is selected from the amino acid sequences shown in the following group: SEQ ID NO: 2 to SEQ ID NO: 3, SEQ ID NO: 22 to SEQ ID NO: 87.

[0740] In one embodiment, the fusion peptide has a fourth domain that can block the PD-L1 / PD-1 pathway, or block other immune checkpoint pathways, or bind to targets on T cells and / or NK cells to bring T cells / NK cells closer to tumor cells, or bind to tumor-associated antigens (TAAs) on other tumor cells.

[0741] In one embodiment of the fusion polypeptide, the fourth domain comprises an antibody or antigen-binding fragment that is the same as or different from the first domain.

[0742] In one embodiment, the fusion peptide, wherein the fourth domain is capable of binding to one or more of the targets shown in the following group: HHLA2, PD-L1, PD-L2, PD-1, OX40, 4-1BB, ICOS, TIGIT, CTLA4, LAG3, CD3, VEGF, VEGFR, CD47, HGF, Trop2, EpCAM, CCR8, CCR4, CCR5, GPRC5D, BCMA, CD19, CD20, HER-2neu, DLL1, HER-3, HER-4, EGFR, PSMA, CEA, MUC-1(mucin), MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC7, CD123, CD33, CD30, CD38, NKG2A, Nkp36, Tim3, and 5T4.

[0743] In one embodiment, the fusion polypeptide has a fourth domain capable of binding PD-L1 and / or PD-1.

[0744] In one embodiment of the fusion polypeptide, the fourth domain comprises an antibody or antigen-binding fragment thereof selected from the group consisting of Sugemalimab, Atezolizumab, Permbrolizumab, and Nivolumab.

[0745] In one embodiment, the fusion polypeptide includes a fourth domain comprising Sugemalimab or an antigen-binding fragment thereof.

[0746] In one embodiment, the fusion polypeptide includes a fourth domain comprising Atezolizumab or an antigen-binding fragment thereof.

[0747] In one embodiment, the fusion polypeptide includes a fourth domain comprising Permbrolizumab or an antigen-binding fragment thereof.

[0748] In one embodiment, the fusion polypeptide includes a fourth domain comprising Nivolumab or an antigen-binding fragment thereof.

[0749] In one embodiment, the fusion polypeptide includes a fourth domain comprising HCDR1, HCDR2, and / or HCDR3 of the antibody heavy chain, the antibody heavy chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272, and SEQ ID NO: 276.

[0750] In one embodiment, the fusion polypeptide includes a fourth domain comprising a heavy chain variable region VH of an antibody heavy chain, the antibody heavy chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272, and SEQ ID NO: 276.

[0751] In one embodiment of the fusion polypeptide, the fourth structural domain comprises an antibody heavy chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272 and SEQ ID NO: 276.

[0752] In one embodiment, the fusion polypeptide includes a fourth domain comprising LCDR1, LCDR2, and / or LCDR3 of a light chain of an antibody light chain, the light chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257, and SEQ ID NO: 265.

[0753] In one embodiment, the fusion polypeptide includes a fourth domain comprising a light chain variable region VL of an antibody light chain, the antibody light chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257, and SEQ ID NO: 265.

[0754] In one embodiment of the fusion polypeptide, the fourth structural domain comprises an antibody light chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257 and SEQ ID NO: 265.

[0755] In one embodiment of the fusion polypeptide, the fourth domain antibody is selected from the group consisting of immunoglobulin antibodies, recombinant antibodies, chimeric antibodies, heavy chain antibodies, single-domain antibodies, and bispecific antibodies, or monoclonal or polyclonal antibodies prepared from the above antibodies.

[0756] In one embodiment of the fusion polypeptide, the fourth domain antigen-binding fragment is selected from one or more of the group consisting of: Fab, Fab', Fv fragment, F(ab')2, F(ab)2, scFv, di-scFv, VHH, and dAb.

[0757] In one embodiment of the fusion polypeptide, the fourth domain comprises a single-chain immunoglobulin domain.

[0758] In one embodiment, the fusion polypeptide includes a fourth domain comprising a single-chain immunoglobulin IgG antibody.

[0759] In one embodiment, the fusion polypeptide, wherein the single-chain immunoglobulin IgG antibody comprises one or more selected from human IgG1, human IgG2, human IgG3, human IgG4, mouse IgG1, mouse IgG2a, mouse IgG2b, and mouse IgG3.

[0760] In one embodiment of the fusion polypeptide, the fourth domain comprises a single-chain immunoglobulin Fc domain.

[0761] In one embodiment of the fusion polypeptide, the fourth domain comprises the Fc domain of a single-chain immunoglobulin IgG antibody.

[0762] In one embodiment of the fusion polypeptide, the fourth structural domain comprises an Fc domain of a single-chain immunoglobulin IgG antibody, wherein the Fc domain of the single-chain immunoglobulin IgG antibody comprises a human IgG1 Fc domain, a human IgG2 Fc domain, a human IgG3 Fc domain, a human IgG4 Fc domain, a mouse IgG1 Fc domain, a mouse IgG2a Fc domain, a mouse IgG2b Fc domain, or a mouse IgG3 Fc domain.

[0763] In one embodiment of the fusion polypeptide, the fourth domain comprises the Fc domain of single-chain human immunoglobulin IgG4.

[0764] In one embodiment of the fusion polypeptide, the fourth domain comprises the Fc domain of single-chain human immunoglobulin IgG1.

[0765] In one embodiment, the fusion polypeptide has a fourth domain comprising the Fc domain of single-chain human immunoglobulin IgG1 and having an L234A / L235A mutation.

[0766] In one embodiment of the fusion polypeptide, the first domain is directly or indirectly connected to the second domain.

[0767] In one embodiment of the fusion polypeptide, the heavy chain of the first domain is directly or indirectly linked to the second domain.

[0768] In one embodiment of the fusion polypeptide, the C-terminus of the heavy chain of the first domain is directly or indirectly connected to the N-terminus of the second domain.

[0769] In one embodiment of the fusion polypeptide, the N-terminus of the heavy chain of the first domain is directly or indirectly connected to the C-terminus of the second domain.

[0770] In one embodiment of the fusion polypeptide, the light chain of the first domain is directly or indirectly connected to the second domain.

[0771] In one embodiment of the fusion polypeptide, the C-terminus of the light chain of the first domain is directly or indirectly connected to the N-terminus of the second domain.

[0772] In one embodiment of the fusion polypeptide, the N-terminus of the light chain of the first domain is directly or indirectly connected to the C-terminus of the second domain.

[0773] The fourth structural domain is directly or indirectly connected to the first structural domain.

[0774] The heavy chain of the fourth structural domain is directly or indirectly connected to the heavy chain of the first structural domain.

[0775] The light chain of the fourth structural domain is directly or indirectly connected to the heavy chain of the first structural domain.

[0776] The heavy chain of the fourth structural domain is directly or indirectly connected to the light chain of the first structural domain.

[0777] The fourth structural domain is directly or indirectly connected to the second structural domain.

[0778] The light chain of the fourth structural domain is directly or indirectly connected to the second structural domain.

[0779] The heavy chain of the fourth structural domain is directly or indirectly connected to the second structural domain.

[0780] In one embodiment, the fusion peptide, wherein the fourth domain is capable of binding to one or more of the targets shown in the following group: HHLA2, PD-L1, PD-L2, PD-1, OX40, 4-1BB, ICOS, TIGIT, CTLA4, LAG3, CD3, VEGF, VEGFR, CD47, HGF, Trop2, EpCAM, CCR8, CCR4, CCR5, GPRC5D, BCMA, CD19, CD20, HER-2neu, DLL1, HER-3, HER-4, EGFR, PSMA, CEA, MUC-1(mucin), MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC7, CD123, CD33, CD30, CD38, NKG2A, Nkp36, Tim3, and 5T4.

[0781] In one embodiment of the fusion polypeptide, the fourth domain is capable of binding CD3.

[0782] In one embodiment of the fusion polypeptide, the fourth domain comprises an antibody or an antigen-binding fragment thereof.

[0783] In one embodiment of the fusion polypeptide, the fourth domain comprises an antibody, its antigen-binding fragment, or a variant thereof selected from the group consisting of: antibody OKT3, antibody UCHT1, antibody SP34, Blinatumamab, Tebentafusp, Mosunetuzumab, and Teclistamab.

[0784] In one embodiment of the fusion polypeptide, the fourth domain may comprise an antibody SP34 mutant or its antigen-binding site.

[0785] In one embodiment of the fusion polypeptide, the fourth domain may comprise an antibody SP34 mutant or its antigen-binding site, the mutation occurring in the CDR region.

[0786] In one embodiment of the fusion polypeptide, the fourth domain may comprise an antibody SP34 mutant or its antigen-binding site, the mutation occurring in the HCDR region, the mutation comprising one or more amino acid site mutations selected from the group consisting of the following based on the antibody SP34 heavy chain variable region SEQ ID NO: 600: T31D, R50K, N100D, N97S, F100fH, S100aA, V100cT.

[0787] In one embodiment of the fusion polypeptide, the fourth domain may comprise an antibody SP34 mutant or its antigen-binding site, the mutation occurring in the LCDR region, the mutation comprising one or more amino acid site mutations selected from the group shown in SEQ ID NO: 601 of the antibody SP34 light chain variable region: N94Q.

[0788] In one embodiment of the fusion polypeptide, the fourth structural domain comprises an amino acid sequence selected from the group shown below: SEQ ID NO: 602-605 and / or SEQ ID NO: 606.

[0789] In one embodiment of the fusion polypeptide, the fourth structural domain includes a complementarity-determining region (CDR), wherein the HCDR1, HCDR2 and / or HCDR3 amino acid sequences or variant sequences thereof of the heavy chain variable region are selected from any of the following amino acid sequences: SEQ ID NO: 607-619; and the LCDR1, LCDR2 and / or LCDR3 amino acid sequences or variant sequences thereof of the light chain variable region contain any of the following amino acid sequences: SEQ ID NO: 613-615, SEQ ID NO: 620.

[0790] In one embodiment of the fusion polypeptide, the fourth domain comprises HCDR1, HCDR2 and / or HCDR3 of the antibody heavy chain, the antibody heavy chain comprising an amino acid sequence selected from any of the following group: SEQ ID NO: 607-619.

[0791] In one embodiment of the fusion polypeptide, the fourth structural domain comprises a heavy chain variable region VH of the antibody heavy chain, the VH comprising an amino acid sequence selected from any of the following groups: SEQ ID NO: 600, SEQ ID NO: 621-627.

[0792] In one embodiment of the fusion polypeptide, the fourth structural domain comprises an antibody heavy chain, the antibody heavy chain comprising any one of the amino acid sequences selected from the group consisting of: SEQ ID NO: 603-606, SEQ ID NO: 628-631.

[0793] In one embodiment of the fusion polypeptide, the fourth domain comprises LCDR1, LCDR2 and / or LCDR3 of the light chain of an antibody light chain, the antibody light chain comprising any one of the amino acid sequences selected from the group consisting of: SEQ ID NO: 613-615, SEQ ID NO: 620.

[0794] In one embodiment of the fusion polypeptide, the fourth domain comprises a light chain variable region VL of the antibody light chain, the VL comprising an amino acid sequence selected from any of the following group: SEQ ID NO: 632-634.

[0795] In one embodiment of the fusion polypeptide, the fourth structural domain comprises an antibody light chain, the antibody light chain comprising any one of the amino acid sequences selected from the group consisting of: SEQ ID NO: 602, SEQ ID NO: 635.

[0796] In one embodiment of the fusion polypeptide, the fourth domain antibody is selected from the group consisting of immunoglobulin antibodies, recombinant antibodies, chimeric antibodies, heavy chain antibodies, single-domain antibodies, and bispecific antibodies, or monoclonal or polyclonal antibodies prepared from the above antibodies.

[0797] In one embodiment of the fusion polypeptide, the fourth domain antigen-binding fragment is selected from one or more of the group consisting of: Fab, Fab', Fv fragment, F(ab')2, F(ab)2, scFv, di-scFv, VHH, and dAb.

[0798] In one embodiment of the fusion polypeptide, the fourth domain comprises a single-chain immunoglobulin domain.

[0799] In one embodiment, the fusion polypeptide includes a fourth domain comprising a single-chain immunoglobulin IgG antibody.

[0800] In one embodiment, the fusion polypeptide, wherein the single-chain immunoglobulin IgG antibody comprises one or more selected from human IgG1, human IgG2, human IgG3, human IgG4, mouse IgG1, mouse IgG2a, mouse IgG2b, and mouse IgG3.

[0801] In one embodiment of the fusion polypeptide, the fourth domain comprises the Fc domain of a single-chain immunoglobulin IgG antibody.

[0802] In one embodiment of the fusion polypeptide, the fourth structural domain comprises an Fc domain of a single-chain immunoglobulin IgG antibody, wherein the Fc domain of the single-chain immunoglobulin IgG antibody comprises a human IgG1 Fc domain, a human IgG2 Fc domain, a human IgG3 Fc domain, a human IgG4 Fc domain, a mouse IgG1 Fc domain, a mouse IgG2a Fc domain, a mouse IgG2b Fc domain, or a mouse IgG3 Fc domain.

[0803] In one embodiment of the fusion polypeptide, the fourth domain comprises the Fc domain of single-chain human immunoglobulin IgG4.

[0804] In one embodiment of the fusion polypeptide, the fourth domain comprises the Fc domain of single-chain human immunoglobulin IgG1.

[0805] In one embodiment, the fusion polypeptide has a fourth domain comprising the Fc domain of single-chain human immunoglobulin IgG1 and having an L234A / L235A mutation.

[0806] In one embodiment of the fusion polypeptide, the fourth domain comprises the Fc domain of single-chain human immunoglobulin IgG1, has an L234A / L235A mutation, and has the necessary mutations in the knobs-into-holes (KiH) pairing, for example: T366 on the CH3 domain of the Knob structure is replaced by a relatively large amino acid residue, such as tyrosine (Y) or tryptophan (W); or, T366 on the CH3 domain of the Hole structure is replaced by serine (S), L368 is replaced by a relatively small amino acid residue, such as alanine (A), and Y407 is replaced by a relatively small amino acid residue, such as threonine (T), alanine (A), or valine (V).

[0807] In one embodiment, the fusion polypeptide, the single-chain immunoglobulin Fc fragment, comprises CH2 and / or CH3 sequences. Alternatively, the fourth structure does not include a CH1 domain.

[0808] In one embodiment of the fusion polypeptide, the first domain is directly or indirectly connected to the second domain.

[0809] In one embodiment of the fusion polypeptide, the heavy chain of the first domain is directly or indirectly linked to the second domain.

[0810] In one embodiment of the fusion polypeptide, the C-terminus of the heavy chain of the first domain is directly or indirectly connected to the N-terminus of the second domain.

[0811] In one embodiment of the fusion polypeptide, the N-terminus of the heavy chain of the first domain is directly or indirectly connected to the C-terminus of the second domain.

[0812] In one embodiment of the fusion polypeptide, the fourth domain is directly or indirectly connected to the first domain.

[0813] In one embodiment of the fusion polypeptide, the heavy chain of the fourth domain is directly or indirectly connected to the heavy chain of the first domain.

[0814] In one embodiment of the fusion polypeptide, the light chain of the fourth domain is directly or indirectly connected to the heavy chain of the first domain.

[0815] The heavy chain of the fourth structural domain is directly or indirectly connected to the light chain of the first structural domain.

[0816] The fourth structural domain is directly or indirectly connected to the second structural domain.

[0817] The light chain of the fourth structural domain is directly or indirectly connected to the second structural domain.

[0818] The heavy chain of the fourth structural domain is directly or indirectly connected to the second structural domain.

[0819] In one embodiment of the fusion polypeptide, the heavy chain Fc fragments of the first and fourth domains are linked by a KIH structure.

[0820] In one embodiment, the fusion polypeptide KIH pairing is achieved by including one or more substitutions in the aforementioned heavy chain Fc fragment, which form heterodimer pairings between the heavy chains.

[0821] In one embodiment of the fusion polypeptide, the indirect connection comprises a linker.

[0822] In one embodiment, the linker comprises an amino acid sequence selected from the group shown below: SEQ ID NO: 16-21.

[0823] In one embodiment, the fusion polypeptide has a first domain capable of blocking HHLA2 / KIR3DL3 signaling, a second domain capable of binding CD28 and / or CTLA4, and a fourth domain capable of binding PD-L1 and / or PD-1; the heavy chain of the fusion polypeptide comprises any amino acid sequence selected from SEQ ID NO: 691 to SEQ ID NO: 724, SEQ ID NO: 741 to SEQ ID NO: 744, and the light chain of the fusion polypeptide comprises any amino acid sequence selected from SEQ ID NO: 687 to SEQ ID NO: 690, SEQ ID NO: 725 to SEQ ID NO: 740, SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, and SEQ ID NO: 235.

[0824] In one embodiment, the fusion polypeptide has a first domain capable of blocking HHLA2 / KIR3DL3 signaling, a second domain capable of binding CD28 and / or CTLA4, and a fourth domain capable of binding CD3; the heavy chain of the fusion polypeptide comprises any amino acid sequence selected from SEQ ID NO: 603-606, SEQ ID NO: 628-631, and SEQ ID NO: 636-641, and the light chain of the fusion polypeptide comprises any amino acid sequence selected from SEQ ID NO: 602 and SEQ ID NO: 635.

[0825] On the other hand, this application provides a fusion polypeptide comprising a first domain, a second domain, a third domain and a fourth domain, wherein the first domain is capable of blocking HHLA2 / KIR3DL3 signaling, the second domain is capable of binding CD28 and / or CTLA4, the third domain is capable of activating an innate immune response, and the fourth domain is capable of binding to T cells and / or NK cells and / or tumor cells.

[0826] In one embodiment of the fusion polypeptide, the first domain is capable of binding HHLA2.

[0827] In one embodiment, the fusion polypeptide has a first domain comprising an antibody or an antigen-binding fragment thereof.

[0828] In one embodiment of the fusion polypeptide, the first domain has the following CDRs or mutations thereof: LCDR1 selected from SEQ ID NO:245, 253, 261; LCDR2 selected from SEQ ID NO:246, 254; LCDR3 selected from SEQ ID NO:247, 255, 271; and HCDR1 selected from SEQ ID NO:242, 250, 258, 266, 273, 277; HCDR2 selected from SEQ ID NO:243, 251, 259, 267, 274, 278; and HCDR3 selected from SEQ ID NO:244, 252, 260, 268, 275, 279, 296, wherein the mutation is an insertion, deletion, or substitution of 3, 2, or 1 amino acids in the amino acid sequence of the CDR.

[0829] In one embodiment, the amino acid sequence of HCDR1 in the first domain is shown in SEQ ID NO:242, the amino acid sequence of HCDR2 is shown in SEQ ID NO:243, the amino acid sequence of HCDR3 is shown in SEQ ID NO:244, the amino acid sequence of LCDR1 is shown in SEQ ID NO:245, the amino acid sequence of LCDR2 is shown in SEQ ID NO:246, and the amino acid sequence of LCDR3 is shown in SEQ ID NO:247; or the amino acid sequence of HCDR1 is shown in SEQ ID NO:250, the amino acid sequence of HCDR2 is shown in SEQ ID NO:251, the amino acid sequence of HCDR3 is shown in SEQ ID NO:252, the amino acid sequence of LCDR1 is shown in SEQ ID NO:253, the amino acid sequence of LCDR2 is shown in SEQ ID NO:254, and the amino acid sequence of LCDR3 is shown in SEQ ID NO:255; or the amino acid sequence of HCDR1 is shown in SEQ ID NO:258, the amino acid sequence of HCDR2 is shown in SEQ ID NO:249, and the amino acid sequence of LCDR3 is shown in SEQ ID NO:255. As shown in NO:259, the amino acid sequence of HCDR3 is as shown in SEQ ID NO:260, the amino acid sequence of LCDR1 is as shown in SEQ ID NO:261, the amino acid sequence of LCDR2 is as shown in SEQ ID NO:254, and the amino acid sequence of LCDR3 is as shown in SEQ ID NO:255; or the amino acid sequence of HCDR1 is as shown in SEQ ID NO:266, the amino acid sequence of HCDR2 is as shown in SEQ ID NO:267, the amino acid sequence of HCDR3 is as shown in SEQ ID NO:268, the amino acid sequence of LCDR1 is as shown in SEQ ID NO:261, the amino acid sequence of LCDR2 is as shown in SEQ ID NO:254, and the amino acid sequence of LCDR3 is as shown in SEQ ID NO:271; or the amino acid sequence of HCDR1 is as shown in SEQ ID NO:273, the amino acid sequence of HCDR2 is as shown in SEQ ID NO:274, and the amino acid sequence of HCDR3 is as shown in SEQ ID NO:275; or the amino acid sequence of HCDR1 is as shown in SEQ ID NO:279. As shown in NO:277, the amino acid sequence of HCDR2 is shown in SEQ ID NO:278, and the amino acid sequence of HCDR3 is shown in SEQ ID NO:279.Alternatively, the amino acid sequence of HCDR1 is as shown in SEQ ID NO:273, the amino acid sequence of HCDR2 is as shown in SEQ ID NO:274, and the amino acid sequence of HCDR3 is as shown in SEQ ID NO:296.

[0830] In one embodiment, the first domain includes a heavy chain variable region (VH) and a light chain variable region (VL) of the antibody. The amino acid sequence of VH is selected from SEQ ID NO:280, 282, 284, 286, 288, 290, 292-293, 295, 297, 307, 317, 337, 357, while the amino acid sequence of VL is selected from SEQ ID NO:281, 283, 285, 287, 289, 291, 302, 322, 332. Specific VH / VL combinations include, but are not limited to, SEQ ID NO: 280 / 281, 282 / 283, 284 / 285, 286 / 287, 288 / 289, 290 / 291, 297 / 302, 307 / 302, 317 / 322, 317 / 332, 337 / 322, 337 / 332, and 357 / 332.

[0831] In another embodiment, the first domain comprises the heavy chain variable region VHH of a single-domain antibody, the amino acid sequence of which is selected from SEQ ID NO:292, 293, 295.

[0832] In a further embodiment, the first domain comprises the complete antibody heavy and light chains. The first domain antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 240, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 241; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 248, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 249; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 256, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 257; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 264, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 265; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 368, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 373; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 369, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 373; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 370, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 374; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 241; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 248, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 249; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 256, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 257; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 264, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 265; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 368, and the antibody light chain comprises the amino acid sequence shown in SEQ ID NO: 373; or the antibody heavy The antibody light chain contains the amino acid sequence shown in SEQ ID NO: 375; or the antibody heavy chain contains the amino acid sequence shown in SEQ ID NO: 371, and the antibody light chain contains the amino acid sequence shown in SEQ ID NO: 374; or the antibody heavy chain contains the amino acid sequence shown in SEQ ID NO: 371, and the antibody light chain contains the amino acid sequence shown in SEQ ID NO: 375; or the antibody heavy chain contains the amino acid sequence shown in SEQ ID NO: 372, and the antibody light chain contains the amino acid sequence shown in SEQ ID NO: 375.

[0833] In another embodiment, the first domain comprises the complete antibody heavy chain. The antibody heavy chain of the first domain comprises the amino acid sequence shown in SEQ ID NO: 272; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 276; or the antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 367.

[0834] In another embodiment, the first domain comprises an antibody or an antigen-binding fragment thereof, said antibody or fragment being selected from RP004263 (disclosed in patent WO2023138579A1) and hz2D7 (disclosed in patent WO2020041300A1).

[0835] In another embodiment, the first domain comprises a heavy chain variable region (VH) of the antibody, wherein the heavy chain variable region comprises HCDR1, HCDR2 and / or HCDR3, and its amino acid sequence is selected from SEQ ID NO:236 and SEQ ID NO:238.

[0836] In another embodiment, the first domain comprises the complete heavy chain of the antibody, and the amino acid sequence of the antibody heavy chain is selected from SEQ ID NO:236 and SEQ ID NO:238.

[0837] In another embodiment, the first domain comprises a light chain variable region (VL) of the antibody, wherein the light chain variable region comprises LCDR1, LCDR2 and / or LCDR3, and its amino acid sequence is selected from SEQ ID NO:237 and SEQ ID NO:239.

[0838] In another embodiment, the first domain comprises the complete light chain of the antibody or an antigen-binding fragment thereof, and the amino acid sequence of the antibody light chain is selected from SEQ ID NO:237 and SEQ ID NO:239. In one embodiment of the fusion polypeptide, the antibody of the first domain is selected from the group consisting of: recombinant antibodies, single-domain antibodies, heavy-chain antibodies, chimeric antibodies, humanized antibodies, fully human antibodies, bispecific antibodies, trispecific antibodies, antibody-drug conjugates (ADCs), Fc fusion proteins, monoclonal antibodies, or polyclonal antibodies.

[0839] Preferably, the anti-B7-H7 antibody or its antigen-binding fragment described in this invention is selected from one or more of the following groups: Fab, Fab', Fv fragment, F(ab')2, F(ab)2, scFv, di-scFv, VHH, dAb, and sdAb.

[0840] In one embodiment of the fusion polypeptide, the first domain comprises a single-chain immunoglobulin domain.

[0841] For example, the single-chain immunoglobulin IgG antibody comprises one or more selected from human IgG1, human IgG2, human IgG3, human IgG4, mouse IgG1, mouse IgG2a, mouse IgG2b and mouse IgG3.

[0842] For example, the first domain includes the Fc domain of a single-chain immunoglobulin IgG antibody, wherein the Fc domain of the single-chain immunoglobulin IgG antibody includes a human IgG1 Fc domain, a human IgG2 Fc domain, a human IgG3 Fc domain, a human IgG4 Fc domain, a mouse IgG1 Fc domain, a mouse IgG2a Fc domain, a mouse IgG2b Fc domain, or a mouse IgG3 Fc domain.

[0843] For example, the first domain includes the Fc domain of single-chain human immunoglobulin IgG4.

[0844] In one embodiment, the fusion polypeptide has a first domain single-chain immunoglobulin Fc fragment containing CH2 and / or CH3 sequences.

[0845] In one embodiment, the fusion polypeptide, the single-chain immunoglobulin Fc fragment, comprises CH2 and / or CH3 sequences. Alternatively, the first structure does not include a CH1 domain.

[0846] In one embodiment of the fusion polypeptide, the first domain comprises the Fc domain of single-chain human immunoglobulin IgG4 and has the necessary mutations in the knobs-into-holes (KiH) pairing, for example: T366 on the CH3 domain of the Knob structure is replaced by a relatively large amino acid residue, such as tyrosine (Y) or tryptophan (W); or, T366 on the CH3 domain of the Hole structure is replaced by serine (S), L368 is replaced by a relatively small amino acid residue, such as alanine (A), and Y407 is replaced by a relatively small amino acid residue, such as threonine (T), alanine (A), or valine (V).

[0847] In one embodiment of the fusion polypeptide, the second domain comprises CD86 or CD80 or a functionally active fragment thereof, or / and a variant of CD86 or CD80.

[0848] In one embodiment of the fusion polypeptide, the second domain is selected from the group consisting of CD86 or CD80 derived from humans or mice, or functionally active fragments thereof.

[0849] In one embodiment of the fusion polypeptide, the second domain comprises the IgV domain of CD86 or CD80 or a functionally active fragment thereof.

[0850] In one embodiment of the fusion polypeptide, the second domain comprises the extracellular domain of CD86 or CD80 or a functionally active fragment thereof.

[0851] In one embodiment, the fusion polypeptide includes a second domain comprising a CD86 variant polypeptide, the mutant comprising an amino acid substitution mutation of humanized CD86.

[0852] In one embodiment of the fusion polypeptide, the second domain comprises a CD86 variant polypeptide, the CD86 variant polypeptide comprising an IgV domain amino acid substitution mutant of CD86 and / or an extracellular domain amino acid substitution mutant of humanized CD86.

[0853] In one embodiment of the fusion polypeptide, the second domain comprises a CD86 variant polypeptide, the CD86 variant polypeptide comprising an IgV domain amino acid substitution mutant of CD86, the mutation site of the CD86 IgV domain amino acid substitution mutant comprising one, two, three, four, five or more amino acid site mutations selected from the group consisting of: A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

[0854] In one embodiment, the fusion polypeptide includes a second domain comprising a CD86 variant polypeptide comprising an IgV domain amino acid substitution mutant of CD86, the amino acid substitution mutant comprising a combination of the following: Q25I / F33L / H90I, Q25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V , Q25V / F33L / H90V, Q25I / F33V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F3 3L / H90I, A13L / Q25V / F33L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M 60R / H90I, Q25V / F33L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F , Q25I / F33A / H90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13 F / Q25I / F33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H 90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I and Q25I / F33L / H90M.

[0855] In one embodiment of the fusion polypeptide, the second domain comprises a CD86 variant polypeptide, the CD86 variant polypeptide comprising the IgV domain amino acid substitution mutant Q25I / F33L / H90I of CD86.

[0856] In one embodiment, the fusion polypeptide includes a second domain comprising a CD86 variant polypeptide comprising an extracellular domain amino acid substitution mutant of CD86, wherein the extracellular domain amino acid substitution mutant of CD86 comprises one, two, three, four, five, or more amino acid site mutations selected from the group consisting of: A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

[0857] In one embodiment, a CD86 variant peptide comprises an extracellular domain amino acid substitution mutant of CD86, the amino acid substitution mutant comprising combinations shown below: Q25I / F33L / H90I, Q25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V, Q25V / F33L / H90V, Q25I / F33V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F33L / H90I, A 13L / Q25V / F33L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M60R / H90 I. Q25V / F33L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F, Q25I / F33A / H90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13F / Q 25I / F33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I and Q25I / F33L / H90M.

[0858] In one embodiment, a CD86 variant peptide comprises an extracellular domain amino acid substitution mutant of CD86, the amino acid substitution mutant comprising the combination shown below: Q25I / F33L / H90I.

[0859] In one embodiment, a CD86 variant polypeptide comprises an amino acid sequence selected from SEQ ID NO: 22 to SEQ ID NO: 87.

[0860] In one embodiment of the fusion polypeptide, the second domain is selected from the amino acid sequences shown in the following group: SEQ ID NO: 2 to SEQ ID NO: 3, SEQ ID NO: 22 to SEQ ID NO: 87.

[0861] In one embodiment, the fusion polypeptide has a third domain capable of binding to MHCII molecules on antigen-presenting cells.

[0862] In one embodiment, the fusion polypeptide includes a third domain comprising LAG3 or a functionally active fragment thereof, or a variant thereof.

[0863] In one embodiment of the fusion polypeptide, the third domain is selected from the group consisting of: human LAG3 or its functionally active fragments, mouse LAG3 or its functionally active fragments, or the aforementioned LAG3 variants of this application.

[0864] In one embodiment, the fusion polypeptide includes a third domain comprising the extracellular domain of LAG3 or a functionally active fragment thereof.

[0865] In one embodiment, the fusion polypeptide includes, in the third domain, IgD1, IgD2, IgD3 and / or IgD4 of LAG3 or a functionally active fragment thereof.

[0866] In one embodiment, the fusion polypeptide includes, in the third domain, IgD1, IgD1-IgD2, IgD1-IgD2-IgD3, and / or IgD1-IgD2-IgD3-IgD4 of LAG3 or a functionally active fragment thereof.

[0867] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide.

[0868] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising a truncated and / or mutated human LAG3.

[0869] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising a truncated peptide based on the extracellular region of wild-type human LAG3.

[0870] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide, the LAG3 variant polypeptide comprising 0-124 amino acids truncated at the N-terminus of a wild-type human LAG3 extracellular region polypeptide, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acids. 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 5 8, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95 Amino acid sequences of 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124 amino acids;Furthermore, the C-terminus terminates at the following positions on the wild-type LAG3 extracellular polypeptide: amino acid positions 121-167, such as amino acid positions 121, 122-146, 122-167, 123-167, 124-167, 125-167, 126-167, 127-167, 128-167, 129-167, 130-167, 131-167, 132-167, 133-167. 134-167, 135-167, 136-167, 137-167, 138-167, 139-167, 140-167, 141-167, 142-167, 143-167, 144-167, 145-167, 146-167, 147-167, 148-167, 149-167, 150-167, 151-167, 152-167, 153-167, 154-167 The position corresponding to any of the following positions: 155-167, 156-167, 157-167, 158-167, 159-167, 160-167, 161-167, 162-167, 163-167, 164-167, 165-167, 166-167, for example, the C-terminus terminates at the following positions: amino acid positions 121, 122, 123, 124, 125, 126, 127 of the extracellular region polypeptide of wild-type LAG3. The positions corresponding to 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167. In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on a wild-type human LAG3 extracellular region polypeptide with an N-terminus truncated by 0, 5, 21, 37, 45, 60, 71, 74, 79, 81, 84, 89, 94, 99, 104, 109, or 114 amino acids.

[0871] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on a wild-type human LAG3 extracellular region polypeptide with 0, 5, 21, 37, 45, 60, 71, 74, 81, or 99 amino acids truncated at the N-terminus.

[0872] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on a wild-type human LAG3 extracellular region polypeptide with 0, 5, 21, 37, 45, 60, 71, or 74 amino acids truncated at the N-terminus.

[0873] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121-167 at the C-terminus.

[0874] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 122-146 at the C-terminus.

[0875] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167.

[0876] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121, 122, 129, 136, 146, 156, 161, or 167 at the C-terminus.

[0877] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121, 146, 156, 161, or 167 at the C-terminus.

[0878] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 156, 161, or 167 at the C-terminus.

[0879] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an N-terminus truncated by 0, 5, 21, 37, 45, 60, 71, 74, 79, 84, 89, 94, 99, 104, 109, or 114 amino acids based on the wild-type human LAG3 extracellular region polypeptide, and a C-terminus terminating at the following positions of the wild-type LAG3 extracellular region polypeptide: 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 amino acids.

[0880] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising 0, 5, 21, 37, 45, 60, 71, 74, 81, or 99 amino acids truncated at the N-terminus of a wild-type human LAG3 extracellular region polypeptide, and an amino acid sequence terminating at amino acid positions 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 at the C-terminus of the wild-type human LAG3 extracellular region polypeptide.

[0881] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising an N-terminal truncation of 0, 5, 21, 37, 45, 60, 71, or 74 amino acids based on the wild-type human LAG3 extracellular region polypeptide, and an C-terminal termination of the wild-type human LAG3 extracellular region polypeptide at amino acid positions 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167.

[0882] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide comprising, at the N-terminus, truncated by 125-145 amino acids, for example, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, or 145 amino acids; and terminated at the C-terminus at a position corresponding to any of amino acid positions 148-167 of the wild-type LAG3 extracellular polypeptide, for example, 148-167, 149-167, or 149-167. 67, 150-167, 151-167, 152-167, 153-167, 154-167, 155-167, 156-167, 157-167, 158-167, 159-167, 160-167, 161-167, 162-167, 163-167, 164-167, 165-167, 166 The position corresponding to any of the positions in -167, for example, the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 of the extracellular polypeptide of wild-type LAG3.

[0883] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide, the LAG3 variant polypeptide comprising 0-124 amino acids truncated at the N-terminus of a wild-type human LAG3 extracellular region polypeptide, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 amino acids. 1, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 1 03, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124 amino acids; and the C-terminus terminates at the following positions of the wild-type LAG3 extracellular region polypeptide: amino acid positions 1-121 of the wild-type LAG3 extracellular region polypeptide.For example, 1-121, 2-121, 3-121, 4-121, 5-121, 6-121, 7-121, 8-121, 9-121, 10-121, 11-121, 12-121, 13-121, 14-121, 15-121, 16-121, 17-121, 18-121, 19-121, 20-121, 21-121, 22-121, 23-121, 24-121, 25-121, 26-121, 27-121, 28-121, 29-121, 30-121, 31-121, 32-121 33-121, 34-121, 35-121, 36-121, 37-121, 38-121, 39-121, 40-121, 41-121, 42-121, 43-121, 44-121, 45-121, 46-121, 47-121, 48-121, 49-121, 50-121, 51-121, 52-121, 53-121, 54-121, 55-121, 56-121, 57-121, 58-121, 59-121, 60-121, 61-121, 62-121, 63-121 64-121, 65-121, 66-121, 67-121, 68-121, 69-121, 70-121, 71-121, 72-121, 73-121, 74-121, 75-121, 76-121, 77-121, 78-121, 79-121, 80-121, 81-121, 82-121, 83-121, 84-121, 85-121, 86-121, 87-121, 88-121, 89-121, 90-121, 91-121, 92-121, 93-121, 94-12 1. The position corresponding to any of the following positions: 95-121, 96-121, 97-121, 98-121, 99-121, 100-121, 101-121, 102-121, 103-121, 104-121, 105-121, 106-121, 107-121, 108-121, 109-121, 110-121, 111-121, 112-121, 113-121, 114-121, 115-121, 116-121, 117-121, 118-121, 119-121, or 120-121.For example, the C-terminus terminates at the following positions: amino acid positions 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 6 The positions corresponding to 2, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, or 121.

[0884] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation.

[0885] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, the mutation site including the Arg amino acid at position 110.

[0886] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, the amino acid mutation site including a mutation of the Arg amino acid at position 110 to a Lys amino acid.

[0887] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, the amino acid site comprising the Arg amino acid at position 97.

[0888] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, the amino acid mutation site including a mutation of the Arg amino acid at position 97 to the Glu amino acid.

[0889] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing amino acid site mutations, the amino acid mutation sites including R110, R113, R119, R129, G130, and / or R141.

[0890] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R110 site is mutated to K110.

[0891] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R113 site is mutated to K113.

[0892] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R119 site is mutated to K119.

[0893] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R129 site is mutated to K129.

[0894] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the G130 site is mutated to P130, or A130, or T130, or Y130, or S130.

[0895] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R141 site is mutated to K141.

[0896] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide containing an amino acid site mutation, wherein the R141 site is mutated to K141 and / or the G130 site is mutated to P130.

[0897] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide that is truncated by 81 amino acids at the N-terminus and terminated at amino acid position 121 at the C-terminus, with mutations introduced at sites R110, and / or R113, and / or R119.

[0898] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide that is truncated by 99 amino acids at the N-terminus and terminated at amino acid position 146 at the C-terminus, with mutations introduced at sites R129, and / or G130, and / or R141.

[0899] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide that is truncated by 81 amino acids at the N-terminus and terminated at amino acid position 146 at the C-terminus, with mutations introduced at sites R110, and / or R113, and / or R119, and / or R129, and / or G130, and / or R141.

[0900] In one embodiment, the fusion polypeptide includes a third domain comprising a LAG3 variant polypeptide that, compared to the wild-type LAG3 extracellular domain polypeptide, has at least one characteristic selected from the following:

[0901] (1) The N-terminus is truncated by 74 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166 or 167 of the extracellular region polypeptide of wild-type LAG3; wherein, preferably, the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 of the extracellular region polypeptide of wild-type LAG3;

[0902] (2) The N-terminus is truncated by 74 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166 or 167 of the extracellular region polypeptide of wild-type LAG3; wherein, preferably, the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 of the extracellular region polypeptide of wild-type LAG3;

[0903] (3) The N-terminus is truncated by 5 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0904] (4) The N-terminus is truncated by 5 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0905] (5) The N-terminus is truncated by 21 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0906] (6) The N-terminus is truncated by 21 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0907] (7) The N-terminus is truncated by 37 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0908] (8) The N-terminus is truncated by 37 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0909] (9) The N-terminus is truncated by 45 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0910] (10) The N-terminus is truncated by 45 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0911] (11) The N-terminus is truncated by 60 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0912] (12) The N-terminus is truncated by 60 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0913] (13) The N-terminus is truncated by 71 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0914] (14) The N-terminus is truncated by 71 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0915] (15) The N-terminus is truncated by 79 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0916] (16) The N-terminus is truncated by 84 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0917] (17) The N-terminus is truncated by 89 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0918] (18) The N-terminus is truncated by 94 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0919] (19) The N-terminus is truncated by 99 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 146, 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0920] (20) The N-terminus is truncated by 99 amino acids and the C-terminus is terminated at amino acid position 146, and a mutant LAG3 polypeptide variant is introduced at R129, and / or G130, and / or R141 sites.

[0921] (21) The N-terminus is truncated by 104 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0922] (22) The N-terminus is truncated by 109 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0923] (23) The N-terminus is truncated by 114 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0924] (24) The N-terminus is truncated by 0 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0925] (25) The N-terminus is truncated by 0 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3.

[0926] (26) The N-terminus is truncated by 81 amino acids and the C-terminus is terminated at amino acid position 121, and a mutant LAG3 peptide variant is introduced at R110, and / or R113, and / or R119 sites.

[0927] (27) The N-terminus is truncated by 81 amino acids and the C-terminus is terminated at amino acid position 146, and mutated LAG3 peptide variants are introduced at R110, and / or R113, and / or R119, and / or R129, and / or G130, and / or R141 sites.

[0928] In one embodiment of the fusion polypeptide, the third domain comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 5 to SEQ ID NO: 13 and SEQ ID NO: 88 to SEQ ID NO: 227.

[0929] In one embodiment, the fusion peptide has a fourth domain that can block the PD-L1 / PD-1 pathway, or block other immune checkpoint pathways, or bind to targets on T cells and / or NK cells to bring T cells / NK cells closer to tumor cells, or bind to tumor-associated antigens (TAAs) on other tumor cells.

[0930] In one embodiment of the fusion polypeptide, the fourth domain comprises an antibody or antigen-binding fragment that is the same as or different from the first domain.

[0931] In one embodiment of the fusion peptide, the fourth domain is capable of binding to one or more of the targets shown in the following group: HHLA2, PD-L1, PD-L2, PD-1, OX40, 4-1BB, ICOS, TIGIT, CTLA4, LAG3, CD3, VEGF, VEGFR, CD47, HGF, Trop2, EpCAM, CCR8, CCR4, CCR5, GPRC5D, BCMA, CD19, CD20, HER-2neu, DLL1, HER-3, HER-4, EGFR, PSMA, CEA, MUC-1(mucin), MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC7, CD123, CD33, CD30, CD38, NKG2A, Nkp36, Tim3, and 5T4.

[0932] In one embodiment, the fusion polypeptide has a fourth domain capable of binding PD-L1 and / or PD-1.

[0933] In one embodiment of the fusion polypeptide, the fourth domain comprises an antibody or antigen-binding fragment thereof selected from the group consisting of Sugemalimab, Atezolizumab, Permbrolizumab, and Nivolumab.

[0934] In one embodiment, the fusion polypeptide includes a fourth domain comprising Sugemalimab or an antigen-binding fragment thereof.

[0935] In one embodiment, the fusion polypeptide includes a fourth domain comprising Atezolizumab or an antigen-binding fragment thereof.

[0936] In one embodiment, the fusion polypeptide includes a fourth domain comprising Permbrolizumab or an antigen-binding fragment thereof.

[0937] In one embodiment, the fusion polypeptide includes a fourth domain comprising Nivolumab or an antigen-binding fragment thereof.

[0938] In one embodiment, the fusion polypeptide includes a fourth domain comprising HCDR1, HCDR2, and / or HCDR3 of the antibody heavy chain, the antibody heavy chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272, and SEQ ID NO: 276.

[0939] In one embodiment, the fusion polypeptide includes a fourth domain comprising a heavy chain variable region VH of an antibody heavy chain, the antibody heavy chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272, and SEQ ID NO: 276.

[0940] In one embodiment of the fusion polypeptide, the fourth structural domain comprises an antibody heavy chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272 and SEQ ID NO: 276.

[0941] In one embodiment, the fusion polypeptide includes a fourth domain comprising LCDR1, LCDR2, and / or LCDR3 of a light chain of an antibody light chain, the light chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257, and SEQ ID NO: 265.

[0942] In one embodiment, the fusion polypeptide includes a fourth domain comprising a light chain variable region VL of an antibody light chain, the antibody light chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257, and SEQ ID NO: 265.

[0943] In one embodiment of the fusion polypeptide, the fourth structural domain comprises an antibody light chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257 and SEQ ID NO: 265.

[0944] In one embodiment of the fusion polypeptide, the fourth domain antibody is selected from the group consisting of immunoglobulin antibodies, recombinant antibodies, chimeric antibodies, heavy chain antibodies, single-domain antibodies, and bispecific antibodies, or monoclonal or polyclonal antibodies prepared from the above antibodies.

[0945] In one embodiment of the fusion polypeptide, the fourth domain antigen-binding fragment is selected from one or more of the group consisting of: Fab, Fab', Fv fragment, F(ab')2, F(ab)2, scFv, di-scFv, VHH, and dAb.

[0946] In one embodiment of the fusion polypeptide, the fourth domain comprises a single-chain immunoglobulin domain.

[0947] For example, the single-chain immunoglobulin IgG antibody comprises one or more selected from human IgG1, human IgG2, human IgG3, human IgG4, mouse IgG1, mouse IgG2a, mouse IgG2b and mouse IgG3.

[0948] For example, the fourth domain includes the Fc domain of a single-chain immunoglobulin IgG antibody, wherein the Fc domain of the single-chain immunoglobulin IgG antibody includes a human IgG1 Fc domain, a human IgG2 Fc domain, a human IgG3 Fc domain, a human IgG4 Fc domain, a mouse IgG1 Fc domain, a mouse IgG2a Fc domain, a mouse IgG2b Fc domain, or a mouse IgG3 Fc domain.

[0949] For example, the fourth domain includes the Fc domain of single-chain human immunoglobulin IgG4.

[0950] In one embodiment, the fusion polypeptide, wherein the fourth domain single-chain immunoglobulin Fc fragment comprises CH2 and / or CH3 sequences.

[0951] In one embodiment, the fusion polypeptide, the single-chain immunoglobulin Fc fragment, comprises CH2 and / or CH3 sequences. Alternatively, the first structure does not include a CH1 domain.

[0952] In one embodiment of the fusion polypeptide, the fourth domain comprises the Fc domain of single-chain human immunoglobulin IgG4 and has the necessary mutations in the knobs-into-holes (KiH) pairing, for example: T366 on the CH3 domain of the Knob structure is replaced by a relatively large amino acid residue, such as tyrosine (Y) or tryptophan (W); or, T366 on the CH3 domain of the Hole structure is replaced by serine (S), L368 is replaced by a relatively small amino acid residue, such as alanine (A), and Y407 is replaced by a relatively small amino acid residue, such as threonine (T), alanine (A), or valine (V).

[0953] In one embodiment of the fusion polypeptide, the first domain and the third domain are directly or indirectly connected.

[0954] In one embodiment of the fusion polypeptide, the heavy chain of the first domain is directly or indirectly linked to the third domain.

[0955] In one embodiment of the fusion polypeptide, the C-terminus of the heavy chain of the first domain is directly or indirectly connected to the N-terminus of the third domain.

[0956] In one embodiment of the fusion polypeptide, the N-terminus of the heavy chain of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0957] In one embodiment of the fusion polypeptide, the first domain light chain is directly or indirectly connected to the third domain.

[0958] In one embodiment of the fusion polypeptide, the C-terminus of the light chain of the first domain is directly or indirectly connected to the N-terminus of the third domain.

[0959] In one embodiment of the fusion polypeptide, the N-terminus of the light chain of the first domain is directly or indirectly connected to the C-terminus of the third domain.

[0960] In one embodiment, the fusion polypeptide has the second and third domains directly or indirectly connected.

[0961] In one embodiment of the fusion polypeptide, the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0962] In one embodiment of the fusion polypeptide, the N-terminus of the second structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

[0963] In one embodiment of the fusion polypeptide, the first domain is directly or indirectly connected to the second domain, and the second domain is directly or indirectly connected to the third domain.

[0964] In one embodiment of the fusion polypeptide, the C-terminus of the first domain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0965] In one embodiment of the fusion polypeptide, the C-terminus of the heavy chain of the first domain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0966] In one embodiment of the fusion polypeptide, the C-terminus of the light chain of the first domain is directly or indirectly connected to the N-terminus of the second domain, and the C-terminus of the second domain is directly or indirectly connected to the N-terminus of the third domain.

[0967] In one embodiment of the fusion polypeptide, the N-terminus of the first structural domain is directly or indirectly connected to the C-terminus of the second structural domain, and the N-terminus of the second structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

[0968] In ...

Claims

1. Antibodies or antigen-binding fragments that bind to HHLA2 can block the binding of HHLA2 to KIR3DL3.

2. The antibody or antigen-binding fragment as described in claim 1, having the following CDRs or mutations thereof: LCDR1 selected from SEQ ID NO: 245, 253, 261; LCDR2 selected from SEQ ID NO: 246, 254; LCDR3 selected from SEQ ID NO: 247, 255, 271; and HCDR1 selected from SEQ ID NO: 242, 250, 258, 266, 273, 277; HCDR2 selected from SEQ ID NO: 243, 251, 259, 267, 274, 278; and HCDR3 selected from SEQ ID NO: 244, 252, 260, 268, 275, 279, 296, wherein, The mutation is an insertion, deletion, or substitution of 3, 2, or 1 amino acid in the amino acid sequence of the CDR.

3. The antibody or antigen-binding fragment as described in claim 2, wherein, The HCDR1, HCDR2, and HCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:242, SEQ ID NO:243, and SEQ ID NO:244; or The HCDR1, HCDR2, and HCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:250, SEQ ID NO:251, and SEQ ID NO:252; or The HCDR1, HCDR2, and HCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:258, SEQ ID NO:259, and SEQ ID NO:260; or The HCDR1, HCDR2, and HCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:266, SEQ ID NO:267, and SEQ ID NO:268; or The HCDR1, HCDR2, and HCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:273, SEQ ID NO:274, and SEQ ID NO:275; or The HCDR1, HCDR2, and HCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:273, SEQ ID NO:274, and SEQ ID NO:296; or The HCDR1, HCDR2, and HCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:277, SEQ ID NO:278, and SEQ ID NO:

279.

4. The antibody or antigen-binding fragment as described in any of the preceding claims, wherein, LCDR1, LCDR2, and LCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:245, SEQ ID NO:246, and SEQ ID NO:247; or The LCDR1, LCDR2, and LCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:253, SEQ ID NO:254, and SEQ ID NO:255; or LCDR1, LCDR2, and LCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:261, SEQ ID NO:254, and SEQ ID NO:255; or The LCDR1, LCDR2, and LCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:261, SEQ ID NO:254, and SEQ ID NO:

271.

5. The antibody or antigen-binding fragment as described in claim 3, wherein, The HCDR1, HCDR2, and HCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:242, SEQ ID NO:243, and SEQ ID NO:244, and the LCDR1, LCDR2, and LCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:245, SEQ ID NO:246, and SEQ ID NO:247; or The HCDR1, HCDR2, and HCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:250, SEQ ID NO:251, and SEQ ID NO:252, and the LCDR1, LCDR2, and LCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:253, SEQ ID NO:254, and SEQ ID NO:255; or The HCDR1, HCDR2, and HCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:258, SEQ ID NO:259, and SEQ ID NO:260, and the LCDR1, LCDR2, and LCDR3 respectively comprise amino acid sequences selected from SEQ ID NO:261, SEQ ID NO:254, and SEQ ID NO:255; or The HCDR1, HCDR2, and HCDR3 each comprise an amino acid sequence selected from SEQ ID NO:266, SEQ ID NO:267, and SEQ ID NO:268, respectively, and the LCDR1, LCDR2, and LCDR3 each comprise an amino acid sequence selected from SEQ ID NO:261, SEQ ID NO:254, and SEQ ID NO:271, respectively.

6. The antibody or antigen-binding fragment as described in any of the preceding claims further comprises humanized modifications of the heavy chain variable frame region (VH FWR) and / or the light chain variable frame region (VL FWR), wherein, VH FWR includes VH FWR1, VH FWR2, VH FWR3 and VH FWR4, and VL FWR includes VL FWR1, VL FWR2, VL FWR3 and VL FWR4.

7. The antibody or antigen-binding fragment as described in claim 6, wherein, The VH FWR is derived from the variable region framework region of the human antibody heavy chain, and its encoding gene is preferably derived from germline V genes IGHV1-46*01, IGHV1-2*02, and IGHV1-3*01; and / or the VL FWR is derived from the variable region framework region of the human antibody light chain, and its encoding gene is preferably derived from germline V genes IGKV1-NL1*01, IGKV1-5*01, and IGKV3-20*01.

8. The antibody or antigen-binding fragment as described in any one of claims 6-7, wherein, The VH FWR1 comprises the amino acid sequence shown in SEQ ID NO:298; and / or The VH FWR2 comprises the amino acid sequence shown in SEQ ID NO:299; and / or The VH FWR3 includes the amino acid sequences shown in SEQ ID NO: 300, 310, 320, and 340; The VH FWR4 includes the amino acid sequence shown in SEQ ID NO:301; The VL FWR1 includes the amino acid sequences shown in SEQ ID NO:303, 323; and / or The VL FWR2 includes the amino acid sequences shown in SEQ ID NO:304, 324; and / or The VL FWR3 comprises the amino acid sequence shown in SEQ ID NO:305, 325, 335; and / or The VL FWR4 includes the amino acid sequence shown in SEQ ID NO:

306.

9. The antibody or antigen-binding fragment as described in any one of claims 6-8, wherein, The VH FWR1, VH FWR2, VH FWR3, and VH FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:298, SEQ ID NO:299, SEQ ID NO:300, and SEQ ID NO:301; or The VH FWR1, VH FWR2, VH FWR3, and VH FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:298, SEQ ID NO:299, SEQ ID NO:310, and SEQ ID NO:301; or The VH FWR1, VH FWR2, VH FWR3, and VH FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:298, SEQ ID NO:299, SEQ ID NO:320, and SEQ ID NO:301; or The VH FWR1, VH FWR2, VH FWR3 and VH FWR4 respectively include the amino acid sequences shown in SEQ ID NO:298, SEQ ID NO:299, SEQ ID NO:340 and SEQ ID NO:

301.

10. The antibody or antigen-binding fragment according to any one of claims 6-9, wherein, The VL FWR1, VL FWR2, VL FWR3, and VL FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:303, SEQ ID NO:304, SEQ ID NO:305, and SEQ ID NO:306; or The VL FWR1, VL FWR2, VL FWR3, and VL FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:323, SEQ ID NO:324, SEQ ID NO:325, and SEQ ID NO:306; or The VL FWR1, VL FWR2, VL FWR3 and VL FWR4 respectively include the amino acid sequences shown in SEQ ID NO:323, SEQ ID NO:324, SEQ ID NO:335 and SEQ ID NO:

306.

11. The antibody or antigen-binding fragment according to any one of claims 6-10, wherein, The VH FWR1, VH FWR2, VH FWR3, and VH FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:298, SEQ ID NO:299, SEQ ID NO:300, and SEQ ID NO:301, and the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:303, SEQ ID NO:304, SEQ ID NO:305, and SEQ ID NO:306; or The VH FWR1, VH FWR2, VH FWR3, and VH FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:298, SEQ ID NO:299, SEQ ID NO:310, and SEQ ID NO:301, and the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:303, SEQ ID NO:304, SEQ ID NO:305, and SEQ ID NO:306; or The VH FWR1, VH FWR2, VH FWR3, and VH FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:298, SEQ ID NO:299, SEQ ID NO:320, and SEQ ID NO:301, and the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:323, SEQ ID NO:324, SEQ ID NO:325, and SEQ ID NO:306; or The VH FWR1, VH FWR2, VH FWR3, and VH FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:298, SEQ ID NO:299, SEQ ID NO:320, and SEQ ID NO:301, and the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:323, SEQ ID NO:324, SEQ ID NO:335, and SEQ ID NO:306; or The VH FWR1, VH FWR2, VH FWR3, and VH FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:298, SEQ ID NO:299, SEQ ID NO:340, and SEQ ID NO:301, and the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:323, SEQ ID NO:324, SEQ ID NO:325, and SEQ ID NO:306; or The VH FWR1, VH FWR2, VH FWR3, and VH FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:298, SEQ ID NO:299, SEQ ID NO:300, and SEQ ID NO:301, and the VL FWR1, VL FWR2, VL FWR3, and VL FWR4 respectively comprise the amino acid sequences shown in SEQ ID NO:323, SEQ ID NO:324, SEQ ID NO:335, and SEQ ID NO:306; or The VH FWR1, VH FWR2, VH FWR3 and VH FWR4 respectively include the amino acid sequences shown in SEQ ID NO:298, SEQ ID NO:299, SEQ ID NO:340 and SEQ ID NO:301, and the VL FWR1, VL FWR2, VL FWR3 and VL FWR4 respectively include the amino acid sequences shown in SEQ ID NO:323, SEQ ID NO:324, SEQ ID NO:335 and SEQ ID NO:

306.

12. The antibody or antigen-binding fragment as described in any of the preceding claims, wherein the VH comprises an amino acid sequence as shown in any of SEQ ID NO:280, SEQ ID NO:282, SEQ ID NO:284, SEQ ID NO:286, SEQ ID NO:288, SEQ ID NO:290, SEQ ID NO:292, SEQ ID NO:293, SEQ ID NO:295, SEQ ID NO:297, SEQ ID NO:307, SEQ ID NO:317, SEQ ID NO:337, or SEQ ID NO:

357.

13. The antibody or antigen-binding fragment as described in any of the preceding claims, wherein, The VL includes any of the amino acid sequences shown in SEQ ID NO:281, SEQ ID NO:283, SEQ ID NO:285, SEQ ID NO:287, SEQ ID NO:289, SEQ ID NO:291, SEQ ID NO:302, SEQ ID NO:322, and SEQ ID NO:

32.

14. The antibody or antigen-binding fragment as described in any of the preceding claims, wherein, The VH comprises the amino acid sequence shown in SEQ ID NO:284, and the VL comprises the amino acid sequence shown in SEQ ID NO:285; or The VH comprises the amino acid sequence shown in SEQ ID NO:286, and the VL comprises the amino acid sequence shown in SEQ ID NO:287; or The VH comprises the amino acid sequence shown in SEQ ID NO:288, and the VL comprises the amino acid sequence shown in SEQ ID NO:289; or The VH comprises the amino acid sequence shown in SEQ ID NO:290, and the VL comprises the amino acid sequence shown in SEQ ID NO:291; or The VH comprises the amino acid sequence shown in SEQ ID NO:297, and the VL comprises the amino acid sequence shown in SEQ ID NO:302; or The VH comprises the amino acid sequence shown in SEQ ID NO:307, and the VL comprises the amino acid sequence shown in SEQ ID NO:302; or The VH comprises the amino acid sequence shown in SEQ ID NO:317, and the VL comprises the amino acid sequence shown in SEQ ID NO:322; or The VH comprises the amino acid sequence shown in SEQ ID NO:317, and the VL comprises the amino acid sequence shown in SEQ ID NO:332; or The VH comprises the amino acid sequence shown in SEQ ID NO:337, and the VL comprises the amino acid sequence shown in SEQ ID NO:322; or The VH comprises the amino acid sequence shown in SEQ ID NO:357, and the VL comprises the amino acid sequence shown in SEQ ID NO:322; or The VH comprises the amino acid sequence shown in SEQ ID NO:337, and the VL comprises the amino acid sequence shown in SEQ ID NO:

332.

15. The antibody or antigen-binding fragment as described in any of the preceding claims, wherein, The antibody heavy chain comprises an amino acid sequence selected from SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272, SEQ ID NO: 276, SEQ ID NO: 367, SEQ ID NO: 368, SEQ ID NO: 369, SEQ ID NO: 370, SEQ ID NO: 371, and SEQ ID NO:

372.

16. The antibody or antigen-binding fragment as described in any of the preceding claims, wherein, The antibody light chain comprises an amino acid sequence selected from SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257, SEQ ID NO: 265, SEQ ID NO: 373, SEQ ID NO: 374, and SEQ ID NO:

375.

17. The antibody or antigen-binding fragment as described in any of the preceding claims, wherein, The antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 240, and the light chain comprises the amino acid sequence shown in SEQ ID NO: 241; or The antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 248, and the light chain comprises the amino acid sequence shown in SEQ ID NO: 249; or The antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 256, and the light chain comprises the amino acid sequence shown in SEQ ID NO: 257; or The antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 264, and the light chain comprises the amino acid sequence shown in SEQ ID NO: 265; or The antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 368, and the light chain comprises the amino acid sequence shown in SEQ ID NO: 373; or The antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 369, and the light chain comprises the amino acid sequence shown in SEQ ID NO: 373; or The antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 370, and the light chain comprises the amino acid sequence shown in SEQ ID NO: 374; or The antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 370, and the light chain comprises the amino acid sequence shown in SEQ ID NO: 375; or The antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 371, and the light chain comprises the amino acid sequence shown in SEQ ID NO: 374; or The antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 372, and the light chain comprises the amino acid sequence shown in SEQ ID NO: 375; or The antibody heavy chain comprises the amino acid sequence shown in SEQ ID NO: 371, and the light chain comprises the amino acid sequence shown in SEQ ID NO:

375.

18. The antibody or antigen-binding fragment as described in any of the preceding claims may be a recombinant antibody, a single-domain antibody, a heavy-chain antibody, a chimeric antibody, or a bispecific antibody, or a monoclonal antibody or polyclonal antibody prepared from the above-mentioned antibodies.

19. The antigen-binding fragment as described in any of the preceding claims may be a Fab, Fab', Fv fragment, F(ab')2, F(ab)2, scFv, di-scFv, VHH, or dAb.

20. A fusion polypeptide comprising a first domain and a second domain, wherein, The first domain can block HHLA2 / KIR3DL3 signals, and the second domain can bind CD28 and / or CTLA4.

21. The fusion polypeptide of claim 20, wherein, The first domain can bind to HHLA2.

22. The fusion polypeptide according to any one of claims 20-21, wherein, The first domain is an antibody or its antigen-binding fragment.

23. The fusion polypeptide according to any one of claims 20-22, wherein, The first structural domain is as described in any one of claims 1-20.

24. The fusion polypeptide according to any one of claims 20-22, wherein, The first structural domain includes a complementary determinant region or a variable region selected from RP004263 (from patent WO2023138579A1) or hz2D7 (from patent WO2020041300A1).

25. The fusion polypeptide according to any one of claims 20-24, wherein, The second domain contains CD86 or CD80 or a functionally active fragment thereof, or / and a variant of CD86 or CD80.

26. The fusion polypeptide according to any one of claims 20-25, wherein, The second domain is either human-derived or mouse-derived.

27. The fusion polypeptide according to any one of claims 20-26, wherein, The second domain contains the IgV domain of CD86 or CD80 or a functionally active fragment thereof.

28. The fusion polypeptide according to any one of claims 20-27, wherein, The second domain contains the extracellular domain of CD86 or CD80 or a functionally active fragment thereof.

29. The fusion polypeptide according to any one of claims 20-26, wherein, The second domain contains a CD86 variant polypeptide, the mutant containing an amino acid substitution mutation of humanized CD86.

30. The fusion polypeptide according to any one of claims 20-19, wherein, The second domain comprises a CD86 variant polypeptide, which comprises an IgV domain amino acid substitution mutant of CD86 and / or an extracellular domain amino acid substitution mutant of humanized CD86.

31. The fusion polypeptide according to any one of claims 20-30, wherein, The CD86 variant polypeptide comprises an IgV domain amino acid substitution mutant of CD86, wherein the mutation site of the IgV domain amino acid substitution mutant of CD86 comprises one or more amino acid site mutations selected from the group shown below: A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

32. The fusion polypeptide according to any one of claims 20-31, wherein, The CD86 variant peptide comprises an IgV domain amino acid substitution mutant of CD86, wherein the amino acid substitution mutant comprises the combinations shown below: Q25I / F33L / H90I, Q25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V, Q25V / F33L / H90V, Q25I / F33 V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F33L / H90I, A13L / Q25V / F3 3L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M60R / H90I, Q25V / F3 3L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F, Q25I / F33A / H 90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13F / Q25I / F 33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I and Q25I / F33L / H90M.

33. The fusion polypeptide according to any one of claims 20-32, wherein, The CD86 variant polypeptide comprises an IgV domain amino acid substitution mutant of CD86, the amino acid substitution mutant comprising the combination shown below: Q25I / F33L / H90I.

34. The fusion polypeptide according to any one of claims 20-33, wherein, The CD86 variant polypeptide comprises an extracellular domain amino acid substitution mutant of CD86, wherein the extracellular domain amino acid substitution mutant of CD86 comprises one or more amino acid site mutations selected from the group consisting of: A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

35. The fusion polypeptide according to any one of claims 20-34, wherein, The CD86 variant peptide comprises an extracellular domain amino acid substitution mutant of CD86, wherein the amino acid substitution mutant comprises the following combinations: Q25I / F33L / H90I, Q25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V, Q25V / F33L / H90V, Q25I / F33 V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F33L / H90I, A13L / Q25V / F3 3L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M60R / H90I, Q25V / F3 3L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F, Q25I / F33A / H 90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13F / Q25I / F 33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I and Q25I / F33L / H90M.

36. The fusion polypeptide according to any one of claims 20-35, wherein, The CD86 variant polypeptide comprises an extracellular domain amino acid substitution mutant of CD86, wherein the amino acid substitution mutant comprises the combination shown below: Q25I / F33L / H90I.

37. The fusion polypeptide according to any one of claims 20-36, wherein, The second domain is selected from the amino acid sequences shown in the following group: SEQ ID NO: 2 to SEQ ID NO: 3, SEQ ID NO: 22 to SEQ ID NO:

87.

38. The fusion polypeptide according to any one of claims 20-37, wherein, The second domain contains a CD80 variant polypeptide, the mutant containing an amino acid substitution mutation of humanized CD80.

39. The fusion polypeptide according to any one of claims 20-38, wherein, The second domain comprises a CD80 variant polypeptide, which comprises an IgV domain amino acid substitution mutant of CD80 and / or an extracellular domain amino acid substitution mutant of humanized CD80.

40. The fusion polypeptide according to any one of claims 20-39, wherein, The first domain is directly or indirectly connected to the second domain.

41. The fusion polypeptide according to any one of claims 20-40, wherein, The first domain heavy chain is directly or indirectly connected to the second domain.

42. The fusion polypeptide according to any one of claims 20-41, wherein, The C-terminus of the first structural domain heavy chain is directly or indirectly connected to the N-terminus of the second structural domain.

43. The fusion polypeptide according to any one of claims 20-42, wherein, The N-terminus of the first structural domain heavy chain is directly or indirectly connected to the C-terminus of the second structural domain.

44. The fusion polypeptide according to any one of claims 20-43, wherein, The first domain light chain is directly or indirectly connected to the second domain.

45. The fusion polypeptide according to any one of claims 20-44, wherein, The C-terminus of the light chain of the first structural domain is directly or indirectly connected to the N-terminus of the second structural domain.

46. ​​The fusion polypeptide according to any one of claims 20-45, wherein, The N-terminus of the light chain of the first structural domain is directly or indirectly connected to the C-terminus of the second structural domain.

47. The fusion polypeptide according to any one of claims 20-46, wherein, The indirect connection includes connections via connector sub-connections.

48. The fusion polypeptide according to any one of claims 20-47, wherein, The linker comprises an amino acid sequence selected from the group shown below: SEQ ID NO: 16-21.

49. The fusion polypeptide according to any one of claims 20-48, wherein, The fusion polypeptide comprises an amino acid sequence selected from the group shown below: SEQ ID NO: 400-496, SEQ ID NO:

639.

50. The fusion polypeptide according to any one of claims 20-49, wherein, It also includes a third domain, which can activate the innate immune response.

51. The fusion polypeptide of claim 50, wherein, The third domain can bind to MHCII molecules on antigen-presenting cells.

52. The fusion polypeptide according to any one of claims 50-51, wherein, The third domain is LAG3 or a functional fragment thereof, or a variant polypeptide thereof.

53. The fusion polypeptide according to any one of claims 50-52, wherein, The LAG3 of the third structural domain or its functional fragments are derived from humans or mice.

54. The fusion polypeptide according to any one of claims 50-53, wherein, The third domain contains the extracellular domain of LAG3 or a functionally active fragment thereof.

55. The fusion polypeptide according to any one of claims 50-54, wherein, The third domain contains IgD1, IgD2, IgD3 and / or IgD4 of LAG3 or their functionally active fragments.

56. The fusion polypeptide according to any one of claims 50-55, wherein, The third domain comprises IgD1, IgD1-IgD2, IgD1-IgD2-IgD3, and / or IgD1-IgD2-IgD3-IgD4 or their functionally active fragments of LAG3.

57. The fusion polypeptide according to any one of claims 50-56, wherein, The third domain contains a LAG3 variant peptide, which contains a truncated and / or mutated human LAG3.

58. The fusion polypeptide according to any one of claims 50-57, wherein, The third domain contains a LAG3 variant polypeptide, which comprises a truncated version of the wild-type human LAG3 extracellular region polypeptide.

59. The fusion polypeptide according to any one of claims 50-58, wherein, The LAG3 variant peptide comprises an amino acid sequence of 0-124 amino acids or 125-145 amino acids truncated at the N-terminus of a wild-type human LAG3 extracellular region peptide.

60. The fusion polypeptide according to any one of claims 50-59, wherein, The LAG3 variant peptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region peptide with 0, 5, 21, 37, 45, 60, 71, 74, 79, 81, 84, 89, 94, 99, 104, 109, or 114 amino acids truncated at the N-terminus; or, the LAG3 variant peptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region peptide with 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, or 135 amino acids truncated at the N-terminus. 136, 137, 138, 139, 140, 141, 142, 143, 144, or 145 amino acids; or, the LAG3 variant polypeptide comprises 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 amino acids truncated at the N-terminus of the wild-type human LAG3 extracellular region polypeptide. 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 8 1, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124 amino acids.

61. The fusion polypeptide according to any one of claims 50-60, wherein, The LAG3 variant peptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region peptide with 0, 5, 21, 37, 45, 60, 71, 74, 81, or 99 amino acids truncated at the N-terminus.

62. The fusion polypeptide according to any one of claims 50-61, wherein, The LAG3 variant peptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region peptide with 0, 5, 21, 37, 45, 60, 71, or 74 amino acids truncated at the N-terminus.

63. The fusion polypeptide according to any one of claims 50-62, wherein, The C-terminus of the LAG3 variant polypeptide terminates at the following positions of the wild-type LAG3 extracellular polypeptide: a position corresponding to any of amino acid positions 121-167 of the wild-type LAG3 extracellular polypeptide, a position corresponding to any of amino acid positions 148-167 of the wild-type LAG3 extracellular polypeptide, or a position corresponding to any of amino acid positions 1-121 of the wild-type LAG3 extracellular polypeptide.

64. The fusion polypeptide according to any one of claims 50-63, wherein, The C-terminus of the LAG3 variant polypeptide terminates at the following position of the wild-type LAG3 extracellular polypeptide: a position corresponding to any of the amino acid positions 122-167 of the wild-type LAG3 extracellular polypeptide.

65. The fusion polypeptide according to any one of claims 50-64, wherein, The LAG3 variant peptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region peptide terminating at amino acid positions 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 at the C-terminus; or, the LAG3 variant peptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region peptide terminating at amino acid positions 148, 149, 160, 161, 162, 163, 164, 165, 166, or 167 at the C-terminus. 50, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167; or, the LAG3 variant peptide comprises a peptide based on the wild-type human LAG3 extracellular region terminating at amino acid positions 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 2. 1, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 7 The positions corresponding to 6, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, or 121.

66. The fusion polypeptide according to any one of claims 50-65, wherein, The LAG3 variant polypeptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121, 122, 129, 136, 146, 156, 161, or 167 at the C-terminus.

67. The fusion polypeptide according to any one of claims 50-66, wherein, The LAG3 variant polypeptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121, 146, 156, 161, or 167 at the C-terminus.

68. The fusion polypeptide according to any one of claims 50-67, wherein, The LAG3 variant peptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region peptide terminated at amino acid positions 156, 161, or 167 at the C-terminus.

69. The fusion polypeptide according to any one of claims 50-68, wherein, The LAG3 variant peptide comprises an N-terminus truncated by 0, 5, 21, 37, 45, 60, 71, 74, 79, 84, 89, 94, 99, 104, 109, or 114 amino acids from the wild-type human LAG3 extracellular region peptide, and terminated at the C-terminus at the following positions of the wild-type LAG3 extracellular region peptide: 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 amino acids.

70. The fusion polypeptide according to any one of claims 50-69, wherein, The LAG3 variant peptide comprises an N-terminal truncation of 0, 5, 21, 37, 45, 60, 71, 74, 81, or 99 amino acids based on the wild-type human LAG3 extracellular region peptide, and an C-terminal termination of the wild-type human LAG3 extracellular region peptide at amino acid positions 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167.

71. The fusion polypeptide according to any one of claims 50-70, wherein, The LAG3 variant peptide comprises 0, 5, 21, 37, 45, 60, 71, or 74 amino acids truncated at the N-terminus of the wild-type human LAG3 extracellular region peptide, and terminated at amino acid positions 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 at the C-terminus.

72. The fusion polypeptide according to any one of claims 50-71, wherein, The LAG3 variant peptide contains amino acid site mutations.

73. The fusion polypeptide according to any one of claims 50-72, wherein, The LAG3 variant peptide contains an amino acid site mutation, including the Arg amino acid at position 97.

74. The fusion polypeptide according to any one of claims 50-73, wherein, The LAG3 variant peptide contains amino acid site mutations, including a mutation of the Arg amino acid at position 97 to the Glu amino acid.

75. The fusion polypeptide according to any one of claims 50-74, wherein, The LAG3 variant peptide contains an amino acid site mutation, including the Arg amino acid at position 110.

76. The fusion polypeptide according to any one of claims 50-75, wherein, The LAG3 variant peptide contains amino acid site mutations, including R110, R113, R119, R129, G130, and / or R141.

77. The fusion polypeptide according to any one of claims 50-76, wherein, The LAG3 variant polypeptide contains an amino acid site mutation, with the R110 site mutated to K110.

78. The fusion polypeptide according to any one of claims 50-77, wherein, The LAG3 variant peptide contains an amino acid site mutation, with the R113 site mutation being K113.

79. The fusion polypeptide according to any one of claims 50-78, wherein, The LAG3 variant peptide contains an amino acid site mutation, with the R119 site mutated to K119.

80. The fusion polypeptide according to any one of claims 50-79, wherein, The LAG3 variant peptide contains an amino acid site mutation, with the R129 site mutation being K129.

81. The fusion polypeptide according to any one of claims 50-80, wherein, The LAG3 variant peptide contains an amino acid site mutation, wherein the G130 site mutation is P130, or A130, or T130, or Y130, or S130.

82. The fusion polypeptide according to any one of claims 50-81, wherein, The LAG3 variant peptide contains an amino acid site mutation, with the R141 site mutated to K141.

83. The fusion polypeptide according to any one of claims 50-82, wherein, The LAG3 variant polypeptide contains amino acid site mutations, with the R141 site mutated to K141 and / or the G130 site mutated to P130.

84. The fusion polypeptide according to any one of claims 50-83, wherein, The LAG3 variant peptide has been truncated by 81 amino acids at the N-terminus and terminated at amino acid position 121 at the C-terminus, with mutations introduced at R110, and / or R113, and / or R119 sites.

85. The fusion polypeptide according to any one of claims 50-84, wherein, The LAG3 variant peptide has been truncated by 99 amino acids at the N-terminus and terminated at amino acid position 146 at the C-terminus, with mutations introduced at R129, and / or G130, and / or R141 sites.

86. The fusion polypeptide according to any one of claims 50-85, wherein, The LAG3 variant peptide has been truncated by 81 amino acids at the N-terminus and terminated at amino acid position 146 at the C-terminus, with mutations introduced at sites R110, and / or R113, and / or R119, and / or R129, and / or G130, and / or R141.

87. The fusion polypeptide according to any one of claims 50-86, wherein, The second domain contains a LAG3 variant polypeptide that, compared to the wild-type LAG3 extracellular domain polypeptide, has at least one of the following characteristics: (1) The N-terminus is truncated by 74 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166 or 167 of the extracellular region polypeptide of wild-type LAG3; wherein, preferably, the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 of the extracellular region polypeptide of wild-type LAG3; (2) The N-terminus is truncated by 74 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166 or 167 of the extracellular region polypeptide of wild-type LAG3; wherein, preferably, the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 of the extracellular region polypeptide of wild-type LAG3; (3) The N-terminus is truncated by 5 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (4) The N-terminus is truncated by 5 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (5) The N-terminus is truncated by 21 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (6) The N-terminus is truncated by 21 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (7) The N-terminus is truncated by 37 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (8) The N-terminus is truncated by 37 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (9) The N-terminus is truncated by 45 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (10) The N-terminus is truncated by 45 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (11) The N-terminus is truncated by 60 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (12) The N-terminus is truncated by 60 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (13) The N-terminus is truncated by 71 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (14) The N-terminus is truncated by 71 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (15) The N-terminus is truncated by 79 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (16) The N-terminus is truncated by 84 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (17) The N-terminus is truncated by 89 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (18) The N-terminus is truncated by 94 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (19) The N-terminus is truncated by 99 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 146, 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (20) The N-terminus is truncated by 99 amino acids and the C-terminus is terminated at amino acid position 146, and a mutant LAG3 polypeptide variant is introduced at R129, and / or G130, and / or R141 sites. (21) The N-terminus is truncated by 104 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (22) The N-terminus is truncated by 109 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (23) The N-terminus is truncated by 114 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (24) The N-terminus is truncated by 0 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (25) The N-terminus is truncated by 0 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (26) The N-terminus is truncated by 81 amino acids and the C-terminus is terminated at amino acid position 121, and a mutant LAG3 peptide variant is introduced at R110, and / or R113, and / or R119 sites. (27) The N-terminus is truncated by 81 amino acids and the C-terminus is terminated at amino acid position 146, and mutated LAG3 peptide variants are introduced at R110, and / or R113, and / or R119, and / or R129, and / or G130, and / or R141 sites.

88. The fusion polypeptide according to any one of claims 50-87, wherein, The third domain contains amino acid sequences selected from the group shown below: SEQ ID NO: 5 to SEQ ID NO: 13 and SEQ ID NO: 88 to SEQ ID NO:

227.

89. The fusion polypeptide according to any one of claims 50-88, wherein, The first structural domain is directly or indirectly connected to the third structural domain.

90. The fusion polypeptide according to any one of claims 50-89, wherein, The first domain heavy chain is directly or indirectly connected to the third domain.

91. The fusion polypeptide of claim 90, wherein, The N-terminus of the first structural domain is directly or indirectly connected to the third structural domain.

92. The fusion polypeptide of claim 91, wherein, The N-terminus of the heavy chain of the first structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

93. The fusion polypeptide of claim 91, wherein, The N-terminus of the light chain in the first structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

94. The fusion polypeptide of claim 90, wherein, The C-terminus of the first structural domain is directly or indirectly connected to the third structural domain.

95. The fusion polypeptide of claim 94, wherein, The C-terminus of the heavy chain of the first structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

96. The fusion polypeptide of claim 94, wherein, in, The C-terminus of the light chain in the first structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

97. The fusion polypeptide according to any one of claims 50-96, wherein, The second and third structural domains are directly or indirectly connected.

98. The fusion polypeptide of claim 97, wherein, The C-terminus of the second structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

99. The fusion polypeptide of claim 97, wherein, The N-terminus of the second structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

100. The fusion polypeptide according to any one of claims 50-99, wherein, The first structural domain is directly or indirectly connected to the second structural domain, and the second structural domain is directly or indirectly connected to the third structural domain.

101. The fusion polypeptide of claim 100, wherein, The C-terminus of the first structural domain is directly or indirectly connected to the N-terminus of the second structural domain, and the C-terminus of the second structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

102. The fusion polypeptide of claim 100, wherein, The C-terminus of the first structural domain is directly or indirectly connected to the N-terminus of the second structural domain, and the C-terminus of the second structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

103. The fusion polypeptide of claim 100, wherein, The C-terminus of the first structural domain light chain is directly or indirectly connected to the N-terminus of the second structural domain, and the C-terminus of the second structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

104. The fusion polypeptide of claim 100, wherein, The N-terminus of the first structural domain is directly or indirectly connected to the C-terminus of the second structural domain, and the N-terminus of the second structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

105. The fusion polypeptide of claim 100, wherein, The N-end of the first structural domain is directly or indirectly connected to the C-end of the second structural domain, and the N-end of the second structural domain is directly or indirectly connected to the C-end of the third structural domain.

106. The fusion polypeptide of claim 100, wherein, The N-terminus of the first structural domain light chain is directly or indirectly connected to the C-terminus of the second structural domain, and the N-terminus of the second structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

107. The fusion polypeptide according to any one of claims 50-99, wherein, The first structural domain is directly or indirectly connected to the third structural domain, and the third structural domain is directly or indirectly connected to the second structural domain.

108. The fusion polypeptide of claim 107, wherein, The C-terminus of the first structural domain is directly or indirectly connected to the N-terminus of the third structural domain, and the C-terminus of the third structural domain is directly or indirectly connected to the N-terminus of the second structural domain.

109. The fusion polypeptide of claim 107, wherein, The C-terminus of the first structural domain heavy chain is directly or indirectly connected to the N-terminus of the third structural domain, and the C-terminus of the third structural domain is directly or indirectly connected to the N-terminus of the second structural domain.

110. The fusion polypeptide of claim 107, wherein, The C-terminus of the first structural domain light chain is directly or indirectly connected to the N-terminus of the third structural domain, and the C-terminus of the third structural domain is directly or indirectly connected to the N-terminus of the second structural domain.

111. The fusion polypeptide of claim 107, wherein, The N-terminus of the first structural domain is directly or indirectly connected to the C-terminus of the third structural domain, and the N-terminus of the third structural domain is directly or indirectly connected to the C-terminus of the second structural domain.

112. The fusion polypeptide of claim 107, wherein, The N-terminus of the first structural domain heavy chain is directly or indirectly connected to the C-terminus of the third structural domain, and the N-terminus of the third structural domain is directly or indirectly connected to the C-terminus of the second structural domain.

113. The fusion polypeptide of claim 107, wherein, The N-terminus of the first structural domain light chain is directly or indirectly connected to the C-terminus of the third structural domain, and the N-terminus of the third structural domain is directly or indirectly connected to the C-terminus of the second structural domain.

114. The fusion polypeptide according to any one of claims 50-99, wherein, The first structural domain is directly or indirectly connected to the second structural domain, and the first structural domain is directly or indirectly connected to the third structural domain.

115. The fusion polypeptide of claim 114, wherein, The C-terminus of the first structural domain is directly or indirectly connected to the N-terminus of the second structural domain, and the N-terminus of the first structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

116. The fusion polypeptide of claim 114, wherein, The C-terminus of the first structural domain heavy chain is directly or indirectly connected to the N-terminus of the second structural domain, and the N-terminus of the first structural domain heavy chain is directly or indirectly connected to the C-terminus of the third structural domain.

117. The fusion polypeptide of claim 114, wherein, The C-terminus of the first structural domain light chain is directly or indirectly connected to the N-terminus of the second structural domain, and the N-terminus of the first structural domain light chain is directly or indirectly connected to the C-terminus of the third structural domain.

118. The fusion polypeptide of claim 114, wherein, The C-terminus of the heavy chain of the first structural domain is directly or indirectly connected to the N-terminus of the second structural domain, and the N-terminus of the light chain of the first structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

119. The fusion polypeptide of claim 114, wherein, The C-terminus of the light chain of the first structural domain is directly or indirectly connected to the N-terminus of the second structural domain, and the N-terminus of the heavy chain of the first structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

120. The fusion polypeptide of claim 114, wherein, The N-terminus of the first structural domain is directly or indirectly connected to the C-terminus of the second structural domain, and the C-terminus of the first structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

121. The fusion polypeptide of claim 114, wherein, The N-terminus of the first structural domain heavy chain is directly or indirectly connected to the C-terminus of the second structural domain, and the C-terminus of the first structural domain heavy chain is directly or indirectly connected to the N-terminus of the third structural domain.

122. The fusion polypeptide of claim 114, wherein, The N-terminus of the first structural domain light chain is directly or indirectly connected to the C-terminus of the second structural domain, and the C-terminus of the first structural domain light chain is directly or indirectly connected to the N-terminus of the third structural domain.

123. The fusion polypeptide of claim 114, wherein, The N-terminus of the heavy chain of the first structural domain is directly or indirectly connected to the C-terminus of the second structural domain, and the C-terminus of the light chain of the first structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

124. The fusion polypeptide of claim 114, wherein, The N-terminus of the light chain of the first structural domain is directly or indirectly connected to the C-terminus of the second structural domain, and the C-terminus of the heavy chain of the first structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

125. The fusion polypeptide according to any one of claims 50-124, wherein, The indirect connection comprises a connection via a linker; preferably, the linker comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 16-21.

126. The fusion polypeptide according to any one of claims 50-125, wherein, The fusion polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 412-441, SEQ ID NO: 448-488, SEQ ID NO: 500-519, SEQ ID NO: 528-582, and SEQ ID NO:

774.

127. The fusion polypeptide according to any one of claims 50-126, wherein, It may also include a fourth domain that can bind to T cells and / or NK cells and / or tumor cells.

128. The fusion polypeptide of any one of claims 127, wherein, The fourth domain can block the PD-L1 and PD-1 pathways, or block other known immune checkpoint pathways, or bind to targets on T cells / NK cells to bring T cells / NK cells closer to tumor cells, or bind to TAAs on other tumor cells.

129. The fusion polypeptide according to any one of claims 127-128, wherein, The fourth domain contains an antibody or antigen-binding fragment that is the same as or different from the second domain.

130. The fusion polypeptide according to any one of claims 127-129, wherein, The fourth domain antigen-binding fragment is selected from one or more of the following group: Fab, Fab', Fv fragment, F(ab')2, F(ab)2, scFv, di-scFv, VHH and dAb.

131. The fusion polypeptide according to any one of claims 127-130, wherein, The fourth domain can bind to one or more of the targets shown in the following group: HHLA2, PD-L1, PD-L2, PD-1, OX40, 4-1BB, ICOS, TIGIT, CTLA4, LAG3, CD3, VEGF, VEGFR, CD47, HGF, Trop2, EpCAM, CCR8, CCR4, CCR5, GPRC5D, BCMA, CD19, CD20, HER-2neu, DLL1, HER-3, HER-4, EGFR, PSMA, CEA, MUC-1(mucin), MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC7, CD123, CD33, CD30, CD38, NKG2A, Nkp36, Tim3, and 5T4.

132. The fusion polypeptide of claim 131, wherein, The fourth structural domain can combine PD-L1 and / or PD-1.

133. The fusion polypeptide according to any one of claims 127-132, wherein, The fourth domain comprises an antibody or an antigen-binding fragment thereof selected from the group shown below: Sugemalimab, Atezolizumab, Permbrolizumab, and Nivolumab.

134. The fusion polypeptide according to any one of claims 127-132, wherein, The fourth domain contains Sugemalimab or its antigen-binding fragment, Atezolizumab or its antigen-binding fragment, Permbrolizumab or its antigen-binding fragment, or Nivolumab or its antigen-binding fragment.

135. The fusion polypeptide according to any one of claims 127-134, wherein, The fourth domain comprises HCDR1, HCDR2 and / or HCDR3 of the antibody heavy chain, the antibody heavy chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272 and SEQ ID NO:

276.

136. The fusion polypeptide according to any one of claims 127-135, wherein, The fourth domain comprises the heavy chain variable region VH of the antibody heavy chain, the antibody heavy chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272 and SEQ ID NO:

276.

137. The fusion polypeptide according to any one of claims 127-136, wherein, The fourth domain comprises an antibody heavy chain containing an amino acid sequence selected from the group consisting of: SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272 and SEQ ID NO:

276.

138. The fusion polypeptide according to any one of claims 127-137, wherein, The fourth domain comprises LCDR1, LCDR2 and / or LCDR3 of the antibody light chain, the antibody light chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257 and SEQ ID NO:

265.

139. The fusion polypeptide according to any one of claims 127-138, wherein, The fourth structural domain includes a light chain variable region VL of the antibody light chain, the antibody light chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257 and SEQ ID NO:

265.

140. The fusion polypeptide according to any one of claims 127-139, wherein, The fourth domain comprises an antibody light chain containing an amino acid sequence selected from the group consisting of: SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257 and SEQ ID NO:

265.

141. The fusion polypeptide according to any one of claims 127-140, wherein, The fourth structural domain is directly or indirectly connected to the first structural domain.

142. The fusion polypeptide according to any one of claims 127-141, wherein, The heavy chain of the fourth structural domain is directly or indirectly connected to the heavy chain of the first structural domain.

143. The fusion polypeptide of claim 142, wherein, The heavy chain of the fourth structural domain is directly or indirectly connected to the heavy chain of the first structural domain via disulfide bonds or via complementary stereostructures (knob-into-hole, KiH); or, the antigen-binding fragment of the fourth structural domain is directly or indirectly connected to the heavy chain of the first structural domain, or the antigen-binding fragment of the first structural domain is directly or indirectly connected to the heavy chain of the fourth structural domain.

144. The fusion polypeptide according to any one of claims 127-141, wherein, The light chain of the fourth structural domain is directly or indirectly connected to the heavy chain of the first structural domain.

145. The fusion polypeptide according to any one of claims 127-141, wherein, The heavy chain of the fourth structural domain is directly or indirectly connected to the light chain of the first structural domain.

146. The fusion polypeptide according to any one of claims 127-145, wherein, The fourth structural domain is directly or indirectly connected to the second structural domain.

147. The fusion polypeptide of claim 146, wherein, The light chain of the fourth structural domain is directly or indirectly connected to the second structural domain.

148. The fusion polypeptide of claim 146, wherein, The heavy chain of the fourth structural domain is directly or indirectly connected to the second structural domain.

149. The fusion polypeptide according to any one of claims 127-148, wherein, The fourth structural domain is directly or indirectly connected to the third structural domain.

150. The fusion polypeptide of claim 149, wherein, The light chain of the fourth structural domain is directly or indirectly connected to the third structural domain.

151. The fusion polypeptide of claim 149, wherein, The heavy chain of the fourth structural domain is directly or indirectly connected to the third structural domain.

152. The fusion polypeptide according to any one of claims 127-151, wherein, The indirect connection includes connections via connector sub-connections.

153. The fusion polypeptide of claim 152, wherein, The linker comprises an amino acid sequence selected from the group shown below: SEQ ID NO: 16-21.

154. The fusion polypeptide according to any one of claims 127-153, wherein, The fusion polypeptide comprises an amino acid sequence selected from SEQ ID NO: 700-708, SEQ ID NO: 725-740, and SEQ ID NO: 745-774.

155. The fusion polypeptide of any one of claims 20-49 further comprises a fourth domain capable of binding to T cells and / or NK cells and / or tumor cells.

156. The fusion polypeptide of claim 155, wherein, The fourth domain can block the PD-L1 and PD-1 pathways, or block other known immune checkpoint pathways, or bind to targets on T cells / NK cells to bring T cells / NK cells closer to tumor cells, or bind to TAAs on other tumor cells.

157. The fusion polypeptide according to any one of claims 155-156, wherein, The fourth domain contains an antibody or antigen-binding fragment that is the same as or different from the second domain.

158. The fusion polypeptide according to any one of claims 155-157, wherein, The fourth domain can bind to one or more of the targets shown in the following group: HHLA2, PD-L1, PD-L2, PD-1, OX40, 4-1BB, ICOS, TIGIT, CTLA4, LAG3, CD3, VEGF, VEGFR, CD47, HGF, Trop2, EpCAM, CCR8, CCR4, CCR5, GPRC5D, BCMA, CD19, CD20, HER-2neu, DLL1, HER-3, HER-4, EGFR, PSMA, CEA, MUC-1(mucin), MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC7, CD123, CD33, CD30, CD38, NKG2A, Nkp36, Tim3, and 5T4.

159. The fusion polypeptide according to any one of claims 155-158, wherein, The fourth structural domain can combine PD-L1 and / or PD-1.

160. The fusion polypeptide according to any one of claims 155-159, wherein, The fourth domain comprises an antibody or an antigen-binding fragment thereof selected from the group shown below: Sugemalimab, Atezolizumab, Permbrolizumab, and Nivolumab.

161. The fusion polypeptide according to any one of claims 155-160, wherein, The fourth domain contains Sugemalimab or its antigen-binding fragment, Atezolizumab or its antigen-binding fragment, Permbrolizumab or its antigen-binding fragment, or Nivolumab or its antigen-binding fragment.

162. The fusion polypeptide according to any one of claims 155-161, wherein, The fourth domain comprises HCDR1, HCDR2 and / or HCDR3 of the antibody heavy chain, the antibody heavy chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272 and SEQ ID NO:

276.

163. The fusion polypeptide according to any one of claims 155-162, wherein, The fourth domain comprises the heavy chain variable region VH of the antibody heavy chain, the antibody heavy chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272 and SEQ ID NO:

276.

164. The fusion polypeptide according to any one of claims 155-163, wherein, The fourth domain comprises an antibody heavy chain containing an amino acid sequence selected from the group consisting of: SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272 and SEQ ID NO:

276.

165. The fusion polypeptide according to any one of claims 155-164, wherein, The fourth domain comprises LCDR1, LCDR2 and / or LCDR3 of the antibody light chain, the antibody light chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257 and SEQ ID NO:

265.

166. The fusion polypeptide according to any one of claims 155-165, wherein, The fourth structural domain includes a light chain variable region VL of the antibody light chain, the antibody light chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257 and SEQ ID NO:

265.

167. The fusion polypeptide according to any one of claims 155-166, wherein, The fourth domain comprises an antibody light chain containing an amino acid sequence selected from the group consisting of: SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257 and SEQ ID NO:

265.

168. The fusion polypeptide according to any one of claims 155-167, wherein, The fourth structural domain is directly or indirectly connected to the first structural domain.

169. The fusion polypeptide of claim 168, wherein, The heavy chain of the fourth structural domain is directly or indirectly connected to the heavy chain of the first structural domain.

170. The fusion polypeptide of claim 169, wherein, The heavy chain of the fourth structural domain is directly or indirectly connected to the heavy chain of the first structural domain via disulfide bonds or via complementary stereostructures (knob-into-hole, KiH); or, the antigen-binding fragment of the fourth structural domain is directly or indirectly connected to the heavy chain of the first structural domain, or the antigen-binding fragment of the first structural domain is directly or indirectly connected to the heavy chain of the fourth structural domain.

171. The fusion polypeptide of claim 168, wherein, The light chain of the fourth structural domain is directly or indirectly connected to the heavy chain of the first structural domain.

172. The fusion polypeptide of claim 168, wherein, The heavy chain of the fourth structural domain is directly or indirectly connected to the light chain of the first structural domain.

173. The fusion polypeptide according to any one of claims 155-172, wherein, The fourth structural domain is directly or indirectly connected to the second structural domain.

174. The fusion polypeptide of claim 173, wherein, The light chain of the fourth structural domain is directly or indirectly connected to the second structural domain.

175. The fusion polypeptide of claim 173, wherein, The heavy chain of the fourth structural domain is directly or indirectly connected to the second structural domain.

176. The fusion polypeptide according to any one of claims 155-175, wherein, In one embodiment of the fusion polypeptide, the indirect linking comprises a linker; preferably, the linker comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 16-21.

177. The fusion polypeptide according to any one of claims 155-176, wherein, The fusion polypeptide heavy chain comprises any amino acid sequence selected from SEQ ID NO: 691 to SEQ ID NO: 724, SEQ ID NO: 741 to SEQ ID NO: 744, and the fusion polypeptide light chain comprises any amino acid sequence selected from SEQ ID NO: 687 to SEQ ID NO: 690, SEQ ID NO: 725 to SEQ ID NO: 740, SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235; or, the fusion polypeptide heavy chain comprises any amino acid sequence selected from SEQ ID NO: 603-606, SEQ ID NO: 628-631, SEQ ID NO: 636-641, and the fusion polypeptide light chain comprises any amino acid sequence selected from SEQ ID NO: 602, SEQ ID NO:

635.

178. A fusion polypeptide comprising a first domain and a third domain, wherein, The first domain can block HHLA2 / KIR3DL3 signaling, and the third domain is LAG3 or a functional fragment thereof, or a variant polypeptide thereof.

179. The fusion polypeptide of claim 178, wherein, The first domain can bind to HHLA2.

180. The fusion polypeptide according to claims 178-179, wherein, The first domain is an antibody or its antigen-binding fragment.

181. The fusion polypeptide according to claims 178-180, wherein, The first structural domain is as described in any one of claims 1-19.

182. The fusion polypeptide according to claims 178-180, wherein, The first structural domain includes a complementary determinant region or a variable region selected from RP004263 (from patent WO2023138579A1) or hz2D7 (from patent WO2020041300A1).

183. The fusion polypeptide according to claims 178-182, wherein, The LAG3 of the third structural domain or its functional fragments are derived from humans or mice.

184. The fusion polypeptide according to claims 178-183, wherein, The third domain contains the extracellular domain of LAG3 or a functionally active fragment thereof.

185. The fusion polypeptide according to claims 178-184, wherein, The third domain contains IgD1, IgD2, IgD3 and / or IgD4 of LAG3 or their functionally active fragments.

186. The fusion polypeptide according to claims 178-185, wherein, The third domain comprises IgD1, IgD1-IgD2, IgD1-IgD2-IgD3, and / or IgD1-IgD2-IgD3-IgD4 or their functionally active fragments of LAG3.

187. The fusion polypeptide according to claims 178-186, wherein, The third domain contains a LAG3 variant peptide, which contains a truncated and / or mutated human LAG3.

188. The fusion polypeptide according to claims 178-187, wherein, The third domain contains a LAG3 variant polypeptide, which comprises a truncated version of the wild-type human LAG3 extracellular region polypeptide.

189. The fusion polypeptide according to claims 178-188, wherein, The LAG3 variant peptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region peptide with 0-124 amino acids truncated at the N-terminus.

190. The fusion polypeptide according to claims 178-189, wherein, The LAG3 variant peptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region peptide with 0, 5, 21, 37, 45, 60, 71, 74, 79, 81, 84, 89, 94, 99, 104, 109, or 114 amino acids truncated at the N-terminus.

191. The fusion polypeptide according to claims 178-190, wherein, The LAG3 variant peptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region peptide with 0, 5, 21, 37, 45, 60, 71, 74, 81, or 99 amino acids truncated at the N-terminus.

192. The fusion polypeptide according to claims 178-191, wherein, The LAG3 variant peptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region peptide with 0, 5, 21, 37, 45, 60, 71, or 74 amino acids truncated at the N-terminus.

193. The fusion polypeptide according to claims 178-192, wherein, The C-terminus of the LAG3 variant polypeptide terminates at the following position of the wild-type LAG3 extracellular polypeptide: a position corresponding to any of the amino acid positions 121-167 of the wild-type LAG3 extracellular polypeptide.

194. The fusion polypeptide according to claims 178-193, wherein, The C-terminus of the LAG3 variant polypeptide terminates at the following position of the wild-type LAG3 extracellular polypeptide: a position corresponding to any of the amino acid positions 122-167 of the wild-type LAG3 extracellular polypeptide.

195. The fusion polypeptide according to claims 178-194, wherein, The LAG3 variant polypeptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 at the C-terminus.

196. The fusion polypeptide according to claims 178-195, wherein, The LAG3 variant polypeptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121, 122, 129, 136, 146, 156, 161, or 167 at the C-terminus.

197. The fusion polypeptide according to claims 178-196, wherein, The LAG3 variant polypeptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region polypeptide terminated at amino acid positions 121, 146, 156, 161, or 167 at the C-terminus.

198. The fusion polypeptide according to claims 178-197, wherein, The LAG3 variant peptide comprises an amino acid sequence based on the wild-type human LAG3 extracellular region peptide terminated at amino acid positions 156, 161, or 167 at the C-terminus.

199. The fusion polypeptide according to claims 178-198, wherein, The LAG3 variant peptide comprises an N-terminus truncated by 0, 5, 21, 37, 45, 60, 71, 74, 79, 84, 89, 94, 99, 104, 109, or 114 amino acids from the wild-type human LAG3 extracellular region peptide, and terminated at the C-terminus at the following positions of the wild-type LAG3 extracellular region peptide: 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 amino acids.

200. The fusion polypeptide according to claims 178-199, wherein, The LAG3 variant peptide comprises an N-terminal truncation of 0, 5, 21, 37, 45, 60, 71, 74, 81, or 99 amino acids based on the wild-type human LAG3 extracellular region peptide, and an C-terminal termination of the wild-type human LAG3 extracellular region peptide at amino acid positions 121, 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167.

201. The fusion polypeptide according to claims 178-200, wherein, The LAG3 variant peptide comprises 0, 5, 21, 37, 45, 60, 71, or 74 amino acids truncated at the N-terminus of the wild-type human LAG3 extracellular region peptide, and terminated at amino acid positions 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, or 167 at the C-terminus.

202. The fusion polypeptide according to claims 178-201, wherein, The LAG3 variant peptide contains amino acid site mutations.

203. The fusion polypeptide according to claims 178-202, wherein, The LAG3 variant peptide contains an amino acid site mutation, including the Arg amino acid at position 97.

204. The fusion polypeptide of claim 203, wherein, The LAG3 variant peptide contains amino acid site mutations, including a mutation of the Arg amino acid at position 97 to the Glu amino acid.

205. The fusion polypeptide according to claims 178-204, wherein, The LAG3 variant peptide contains an amino acid site mutation, including the Arg amino acid at position 110.

206. The fusion polypeptide of claim 205, wherein, The LAG3 variant peptide contains amino acid site mutations, including R110, R113, R119, R129, G130, and / or R141.

207. The fusion polypeptide of claim 206, wherein, The LAG3 variant polypeptide contains an amino acid site mutation, with the R110 site mutated to K110.

208. The fusion polypeptide according to claims 178-207, wherein, The LAG3 variant peptide contains an amino acid site mutation, with the R113 site mutation being K113.

209. The fusion polypeptide according to claims 178-208, wherein, The LAG3 variant peptide contains an amino acid site mutation, with the R119 site mutated to K119.

210. The fusion polypeptide according to claims 178-209, wherein, The LAG3 variant peptide contains an amino acid site mutation, with the R129 site mutation being K129.

211. The fusion polypeptide according to claims 178-210, wherein, The LAG3 variant peptide contains an amino acid site mutation, wherein the G130 site mutation is P130, or A130, or T130, or Y130, or S130.

212. The fusion polypeptide according to claims 178-211, wherein, The LAG3 variant peptide contains an amino acid site mutation, with the R141 site mutated to K141.

213. The fusion polypeptide according to claims 178-212, wherein, The LAG3 variant polypeptide contains amino acid site mutations, with the R141 site mutated to K141 and / or the G130 site mutated to P130.

214. The fusion polypeptide according to claims 178-213, wherein, The LAG3 variant peptide has been truncated by 81 amino acids at the N-terminus and terminated at amino acid position 121 at the C-terminus, with mutations introduced at R110, and / or R113, and / or R119 sites.

215. The fusion polypeptide according to claims 178-214, wherein, The LAG3 variant peptide has been truncated by 99 amino acids at the N-terminus and terminated at amino acid position 146 at the C-terminus, with mutations introduced at R129, and / or G130, and / or R141 sites.

216. The fusion polypeptide according to claims 178-215, wherein, The LAG3 variant peptide has been truncated by 81 amino acids at the N-terminus and terminated at amino acid position 146 at the C-terminus, with mutations introduced at sites R110, and / or R113, and / or R119, and / or R129, and / or G130, and / or R141.

217. The fusion polypeptide according to claims 178-216, wherein, The second domain contains a LAG3 variant polypeptide that, compared to the wild-type LAG3 extracellular domain polypeptide, has at least one of the following characteristics: (1) The N-terminus is truncated by 74 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166 or 167 of the extracellular region polypeptide of wild-type LAG3; wherein, preferably, the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 of the extracellular region polypeptide of wild-type LAG3; (2) The N-terminus is truncated by 74 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166 or 167 of the extracellular region polypeptide of wild-type LAG3; wherein, preferably, the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 of the extracellular region polypeptide of wild-type LAG3; (3) The N-terminus is truncated by 5 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (4) The N-terminus is truncated by 5 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (5) The N-terminus is truncated by 21 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (6) The N-terminus is truncated by 21 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (7) The N-terminus is truncated by 37 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (8) The N-terminus is truncated by 37 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (9) The N-terminus is truncated by 45 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (10) The N-terminus is truncated by 45 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (11) The N-terminus is truncated by 60 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (12) The N-terminus is truncated by 60 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (13) The N-terminus is truncated by 71 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (14) The N-terminus is truncated by 71 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (15) The N-terminus is truncated by 79 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (16) The N-terminus is truncated by 84 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (17) The N-terminus is truncated by 89 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (18) The N-terminus is truncated by 94 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (19) The N-terminus is truncated by 99 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 146, 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (20) The N-terminus is truncated by 99 amino acids and the C-terminus is terminated at amino acid position 146, and a mutant LAG3 polypeptide variant is introduced at R129, and / or G130, and / or R141 sites. (21) The N-terminus is truncated by 104 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (22) The N-terminus is truncated by 109 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (23) The N-terminus is truncated by 114 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (24) The N-terminus is truncated by 0 amino acids, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (25) The N-terminus is truncated by 0 amino acids, the Arg amino acid at position 97 is mutated to the Glu amino acid, and the C-terminus terminates at the following positions: the positions corresponding to amino acid positions 122, 129, 136, 146, 156, 161 or 167 of the extracellular region polypeptide of wild-type LAG3. (26) The N-terminus is truncated by 81 amino acids and the C-terminus is terminated at amino acid position 121, and a mutant LAG3 peptide variant is introduced at R110, and / or R113, and / or R119 sites. (27) The N-terminus is truncated by 81 amino acids and the C-terminus is terminated at amino acid position 146, and mutated LAG3 peptide variants are introduced at R110, and / or R113, and / or R119, and / or R129, and / or G130, and / or R141 sites.

218. The fusion polypeptide according to claims 178-217, wherein, The first structural domain is directly or indirectly connected to the third structural domain.

219. The fusion polypeptide of claim 218, wherein, The first domain heavy chain is directly or indirectly connected to the third domain.

220. The fusion polypeptide of claim 219, wherein, The C-terminus of the first structural domain heavy chain is directly or indirectly connected to the N-terminus of the third structural domain.

221. The fusion polypeptide of claim 219, wherein, The N-terminus of the first structural domain heavy chain is directly or indirectly connected to the C-terminus of the second structural domain.

222. The fusion polypeptide of claim 218, wherein, The first structural domain light chain is directly or indirectly connected to the third structural domain.

223. The fusion polypeptide of claim 222, wherein, The C-terminus of the light chain in the first structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

224. The fusion polypeptide of claim 222, wherein, The N-terminus of the light chain in the first structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

225. The fusion polypeptide according to claims 178-224, wherein, The indirect connection includes connections via connector sub-connections.

226. The fusion polypeptide according to claims 178-225, wherein, The linker comprises an amino acid sequence selected from the group shown below: SEQ ID NO: 16-21.

227. The fusion polypeptide according to claims 178-226, wherein, The fusion polypeptide comprises amino acid sequences selected from the group consisting of: SEQ ID NO: 500-547, SEQ ID NO: 583-586.

228. The fusion peptide of any one of claims 178-227 further comprises a second domain capable of binding CD28 and / or CTLA4.

229. The fusion polypeptide of claim 228, wherein the second domain comprises CD86 or CD80 or a functionally active fragment thereof, or / and a variant of CD86 or CD80.

230. The fusion polypeptide according to claims 228-229, wherein, The second domain is either human-derived or mouse-derived.

231. The fusion polypeptide according to claims 228-230, wherein, The second domain contains the IgV domain of CD86 or CD80 or a functionally active fragment thereof.

232. The fusion polypeptide according to claims 228-231, wherein, The second domain contains the extracellular domain of CD86 or CD80 or a functionally active fragment thereof.

233. The fusion polypeptide according to claims 228-232, wherein, The second domain contains a CD86 variant polypeptide, the mutant containing an amino acid substitution mutation of humanized CD86.

234. The fusion polypeptide according to claims 228-233, wherein, The second domain comprises a CD86 variant polypeptide, which comprises an IgV domain amino acid substitution mutant of CD86 and / or an extracellular domain amino acid substitution mutant of humanized CD86.

235. The fusion polypeptide according to claims 228-234, wherein, The CD86 variant polypeptide comprises an IgV domain amino acid substitution mutant of CD86, wherein the mutation site of the IgV domain amino acid substitution mutant of CD86 comprises one or more amino acid site mutations selected from the group shown below: A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

236. The fusion polypeptide according to claims 228-235, wherein, The CD86 variant peptide comprises an IgV domain amino acid substitution mutant of CD86, wherein the amino acid substitution mutant comprises the combinations shown below: Q25I / F33L / H90I, Q25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V, Q25V / F33L / H90V, Q25I / F33 V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F33L / H90I, A13L / Q25V / F3 3L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M60R / H90I, Q25V / F3 3L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F, Q25I / F33A / H 90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13F / Q25I / F 33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I and Q25I / F33L / H90M.

237. The fusion polypeptide according to claims 228-236, wherein, The CD86 variant polypeptide comprises an IgV domain amino acid substitution mutant of CD86, the amino acid substitution mutant comprising the combination shown below: Q25I / F33L / H90I.

238. The fusion polypeptide according to claims 228-237, wherein, The CD86 variant polypeptide comprises an extracellular domain amino acid substitution mutant of CD86, wherein the extracellular domain amino acid substitution mutant of CD86 comprises one or more amino acid site mutations selected from the group consisting of: A13I, A13L, A13F, A13M, Q25A, Q25I, Q25V, Q25F, Q25M, F33A, F33L, F33V, F33M, M60R, I89A, I89L, I89V, I89F, I89M, H90I, H90V, H90M, H90F.

239. The fusion polypeptide according to claims 228-238, wherein, The CD86 variant peptide comprises an extracellular domain amino acid substitution mutant of CD86, wherein the amino acid substitution mutant comprises the following combinations: Q25I / F33L / H90I, Q25V / F33L / H90I, Q25I / F33V / H90I, Q25V / F33V / H90I, Q25I / F33L / H90V, Q25V / F33L / H90V, Q25I / F33 V / H90V, Q25V / F33V / H90V, A13L / Q25I / F33L / H90I, A13I / Q25I / F33L / H90I, A13L / Q25V / F3 3L / H90I, A13I / Q25V / F33L / H90I, Q25I / F33L / I89L / H90I, Q25I / F33L / M60R / H90I, Q25V / F3 3L / I89L / H90I, Q25V / F33L / M60R / H90I, Q25F / F33L / H90I, Q25I / F33L / H90F, Q25I / F33A / H 90I, Q25I / H90I, Q25I, H90I, Q25V / H90V, Q25V / H90I, Q25F / H90I, Q25F / H90V, A13F / Q25I / F 33L / H90I, A13M / Q25I / F33L / H90I, Q25A / F33L / H90I, Q25M / F33L / H90I, Q25I / F33M / H90I, Q25I / F33L / I89V / H90I, Q25I / F33L / I89F / H90I, Q25I / F33L / I89M / H90I and Q25I / F33L / H90M.

240. The fusion polypeptide according to claims 228-239, wherein, The CD86 variant polypeptide comprises an extracellular domain amino acid substitution mutant of CD86, wherein the amino acid substitution mutant comprises the combination shown below: Q25I / F33L / H90I.

241. The fusion polypeptide according to claims 228-240, wherein, The second domain is selected from the amino acid sequences shown in the following group: SEQ ID NO: 2 to SEQ ID NO: 3, SEQ ID NO: 22 to SEQ ID NO:

87.

242. The fusion polypeptide according to claims 228-241, wherein, The second domain contains a CD80 variant polypeptide, the mutant containing an amino acid substitution mutation of humanized CD80.

243. The fusion polypeptide according to claims 228-242, wherein, The second domain comprises a CD80 variant polypeptide, which comprises an IgV domain amino acid substitution mutant of CD80 and / or an extracellular domain amino acid substitution mutant of humanized CD80.

244. The fusion polypeptide according to claims 228-243, wherein, The first and second structural domains are directly or indirectly connected.

245. The fusion polypeptide of claim 244, wherein, The first domain heavy chain is directly or indirectly connected to the second domain.

246. The fusion polypeptide of claim 245, wherein, The C-terminus of the first structural domain heavy chain is directly or indirectly connected to the N-terminus of the second structural domain.

247. The fusion polypeptide of claim 245, wherein, The N-terminus of the first structural domain heavy chain is directly or indirectly connected to the C-terminus of the second structural domain.

248. The fusion polypeptide of claim 244, wherein, The first domain light chain is directly or indirectly connected to the second domain.

249. The fusion polypeptide of claim 248, wherein, The C-terminus of the light chain of the first structural domain is directly or indirectly connected to the N-terminus of the second structural domain.

250. The fusion polypeptide of claim 248, wherein, The N-terminus of the light chain of the first structural domain is directly or indirectly connected to the C-terminus of the second structural domain.

251. The fusion polypeptide according to claims 228-250, wherein, The second and third structural domains are directly or indirectly connected.

252. The fusion polypeptide of claim 251, wherein, The C-terminus of the second structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

253. The fusion polypeptide of claim 251, wherein, The N-terminus of the second structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

254. The fusion polypeptide according to claims 228-253, wherein, The first structural domain is directly or indirectly connected to the second structural domain, and the second structural domain is directly or indirectly connected to the third structural domain.

255. The fusion polypeptide of claim 254, wherein, The C-terminus of the first structural domain is directly or indirectly connected to the N-terminus of the second structural domain, and the C-terminus of the second structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

256. The fusion polypeptide of claim 254, wherein, The C-terminus of the first structural domain is directly or indirectly connected to the N-terminus of the second structural domain, and the C-terminus of the second structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

257. The fusion polypeptide of claim 254, wherein, The C-terminus of the first structural domain light chain is directly or indirectly connected to the N-terminus of the second structural domain, and the C-terminus of the second structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

258. The fusion polypeptide of claim 254, wherein, The N-terminus of the first structural domain is directly or indirectly connected to the C-terminus of the second structural domain, and the N-terminus of the second structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

259. The fusion polypeptide of claim 254, wherein, The N-end of the first structural domain is directly or indirectly connected to the C-end of the second structural domain, and the N-end of the second structural domain is directly or indirectly connected to the C-end of the third structural domain.

260. The fusion polypeptide of claim 254, wherein, The N-terminus of the first structural domain light chain is directly or indirectly connected to the C-terminus of the second structural domain, and the N-terminus of the second structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

261. The fusion polypeptide according to claims 228-253, wherein, The first structural domain is directly or indirectly connected to the third structural domain, and the third structural domain is directly or indirectly connected to the second structural domain.

262. The fusion polypeptide of claim 261, wherein, The C-terminus of the first structural domain is directly or indirectly connected to the N-terminus of the third structural domain, and the C-terminus of the third structural domain is directly or indirectly connected to the N-terminus of the second structural domain.

263. The fusion polypeptide of claim 261, wherein, The C-terminus of the first structural domain heavy chain is directly or indirectly connected to the N-terminus of the third structural domain, and the C-terminus of the third structural domain is directly or indirectly connected to the N-terminus of the second structural domain.

264. The fusion polypeptide of claim 261, wherein, The C-terminus of the first structural domain light chain is directly or indirectly connected to the N-terminus of the third structural domain, and the C-terminus of the third structural domain is directly or indirectly connected to the N-terminus of the second structural domain.

265. The fusion polypeptide of claim 261, wherein, The N-terminus of the first structural domain is directly or indirectly connected to the C-terminus of the third structural domain, and the N-terminus of the third structural domain is directly or indirectly connected to the C-terminus of the second structural domain.

266. The fusion polypeptide of claim 261, wherein, The N-terminus of the first structural domain heavy chain is directly or indirectly connected to the C-terminus of the third structural domain, and the N-terminus of the third structural domain is directly or indirectly connected to the C-terminus of the second structural domain.

267. The fusion polypeptide of claim 261, wherein, The N-terminus of the first structural domain light chain is directly or indirectly connected to the C-terminus of the third structural domain, and the N-terminus of the third structural domain is directly or indirectly connected to the C-terminus of the second structural domain.

268. The fusion polypeptide according to claims 228-253, wherein, The first structural domain is directly or indirectly connected to the second structural domain, and the first structural domain is directly or indirectly connected to the third structural domain.

269. The fusion polypeptide of claim 268, wherein, The C-terminus of the first structural domain is directly or indirectly connected to the N-terminus of the second structural domain, and the N-terminus of the first structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

270. The fusion polypeptide of claim 268, wherein, The C-terminus of the first structural domain heavy chain is directly or indirectly connected to the N-terminus of the second structural domain, and the N-terminus of the first structural domain heavy chain is directly or indirectly connected to the C-terminus of the third structural domain.

271. The fusion polypeptide of claim 268, wherein, The C-terminus of the first structural domain light chain is directly or indirectly connected to the N-terminus of the second structural domain, and the N-terminus of the first structural domain light chain is directly or indirectly connected to the C-terminus of the third structural domain.

272. The fusion polypeptide of claim 268, wherein, The C-terminus of the heavy chain of the first structural domain is directly or indirectly connected to the N-terminus of the second structural domain, and the N-terminus of the light chain of the first structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

273. The fusion polypeptide of claim 268, wherein, The C-terminus of the light chain of the first structural domain is directly or indirectly connected to the N-terminus of the second structural domain, and the N-terminus of the heavy chain of the first structural domain is directly or indirectly connected to the C-terminus of the third structural domain.

274. The fusion polypeptide of claim 268, wherein, The N-terminus of the first structural domain is directly or indirectly connected to the C-terminus of the second structural domain, and the C-terminus of the first structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

275. The fusion polypeptide of claim 268, wherein, The N-terminus of the first structural domain heavy chain is directly or indirectly connected to the C-terminus of the second structural domain, and the C-terminus of the first structural domain heavy chain is directly or indirectly connected to the N-terminus of the third structural domain.

276. The fusion polypeptide of claim 268, wherein, The N-terminus of the first structural domain light chain is directly or indirectly connected to the C-terminus of the second structural domain, and the C-terminus of the first structural domain light chain is directly or indirectly connected to the N-terminus of the third structural domain.

277. The fusion polypeptide of claim 268, wherein, The N-terminus of the heavy chain of the first structural domain is directly or indirectly connected to the C-terminus of the second structural domain, and the C-terminus of the light chain of the first structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

278. The fusion polypeptide of claim 268, wherein, The N-terminus of the light chain of the first structural domain is directly or indirectly connected to the C-terminus of the second structural domain, and the C-terminus of the heavy chain of the first structural domain is directly or indirectly connected to the N-terminus of the third structural domain.

279. The fusion polypeptide according to claims 228-278, wherein, The indirect connection includes connections via connector sub-connections.

280. The fusion polypeptide of claim 279, wherein, The linker comprises an amino acid sequence selected from the group shown below: SEQ ID NO: 16-21.

281. The fusion polypeptide according to claims 228-280, wherein, The fusion polypeptide comprises an amino acid sequence selected from the group consisting of: SEQ ID NO: 412-441, SEQ ID NO: 448-488, SEQ ID NO: 500-519, SEQ ID NO: 528-582, and SEQ ID NO:

774.

282. The fusion polypeptide according to claims 228-281, wherein, It may also include a fourth domain that can bind to T cells and / or NK cells and / or tumor cells.

283. The fusion polypeptide of claim 282, wherein, The fourth domain can block the PD-L1 and PD-1 pathways, or block other known immune checkpoint pathways, or bind to targets on T cells / NK cells to bring T cells / NK cells closer to tumor cells, or bind to TAAs on other tumor cells.

284. The fusion polypeptide according to claims 282-283, wherein, The fourth domain contains an antibody or antigen-binding fragment that is the same as or different from the second domain.

285. The fusion polypeptide according to claims 282-284, wherein, The fourth domain can bind to one or more of the targets shown in the following group: HHLA2, PD-L1, PD-L2, PD-1, OX40, 4-1BB, ICOS, TIGIT, CTLA4, LAG3, CD3, VEGF, VEGFR, CD47, HGF, Trop2, EpCAM, CCR8, CCR4, CCR5, GPRC5D, BCMA, CD19, CD20, HER-2neu, DLL1, HER-3, HER-4, EGFR, PSMA, CEA, MUC-1(mucin), MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC7, CD123, CD33, CD30, CD38, NKG2A, Nkp36, Tim3, and 5T4.

286. The fusion polypeptide according to claims 282-282, wherein, The fourth structural domain can combine PD-L1 and / or PD-1.

287. The fusion polypeptide according to claims 282-286, wherein, The fourth domain comprises an antibody or an antigen-binding fragment thereof selected from the group shown below: Sugemalimab, Atezolizumab, Permbrolizumab, and Nivolumab.

288. The fusion polypeptide according to claims 282-287, wherein, The fourth domain contains Sugemalimab or its antigen-binding fragment, Atezolizumab or its antigen-binding fragment, Permbrolizumab or its antigen-binding fragment, or Nivolumab or its antigen-binding fragment.

289. The fusion polypeptide according to claims 282-288, wherein, The fourth domain comprises HCDR1, HCDR2 and / or HCDR3 of the antibody heavy chain, the antibody heavy chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272 and SEQ ID NO:

276.

290. The fusion polypeptide according to claims 282-289, wherein, The fourth domain comprises the heavy chain variable region VH of the antibody heavy chain, the antibody heavy chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272 and SEQ ID NO:

276.

291. The fusion polypeptide according to claims 282-290, wherein, The fourth domain comprises an antibody heavy chain containing an amino acid sequence selected from the group consisting of: SEQ ID NO: 228, SEQ ID NO: 230, SEQ ID NO: 232, SEQ ID NO: 234, SEQ ID NO: 236, SEQ ID NO: 238, SEQ ID NO: 240, SEQ ID NO: 248, SEQ ID NO: 256, SEQ ID NO: 264, SEQ ID NO: 272 and SEQ ID NO:

276.

292. The fusion polypeptide according to claims 282-291, wherein, The fourth domain comprises LCDR1, LCDR2 and / or LCDR3 of the antibody light chain, the antibody light chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257 and SEQ ID NO:

265.

293. The fusion polypeptide according to claims 282-292, wherein, The fourth structural domain includes a light chain variable region VL of the antibody light chain, the antibody light chain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257 and SEQ ID NO:

265.

294. The fusion polypeptide according to claims 282-293, wherein, The fourth domain comprises an antibody light chain containing an amino acid sequence selected from the group consisting of: SEQ ID NO: 229, SEQ ID NO: 231, SEQ ID NO: 233, SEQ ID NO: 235, SEQ ID NO: 237, SEQ ID NO: 239, SEQ ID NO: 241, SEQ ID NO: 249, SEQ ID NO: 257 and SEQ ID NO:

265.

295. The fusion polypeptide according to claims 282-294, wherein, The fourth structural domain is directly or indirectly connected to the first structural domain.

296. The fusion polypeptide of claim 295, wherein, The heavy chain of the fourth structural domain is directly or indirectly connected to the heavy chain of the first structural domain; preferably, the heavy chain of the fourth structural domain is directly or indirectly connected to the heavy chain of the first structural domain through disulfide bonds or through complementary stereostructures (knob-into-hole, KiH); or preferably, the antigen-binding fragment of the fourth structural domain is directly or indirectly connected to the heavy chain of the first structural domain, or the antigen-binding fragment of the first structural domain is directly or indirectly connected to the heavy chain of the fourth structural domain.

297. The fusion polypeptide of claim 295, wherein, The light chain of the fourth structural domain is directly or indirectly connected to the heavy chain of the first structural domain.

298. The fusion polypeptide of claim 295, wherein, The heavy chain of the fourth structural domain is directly or indirectly connected to the light chain of the first structural domain.

299. The fusion polypeptide of claim 295, wherein, The fourth structural domain is directly or indirectly connected to the second structural domain.

300. The fusion polypeptide according to claims 282-299, wherein, The light chain of the fourth structural domain is directly or indirectly connected to the second structural domain.

301. The fusion polypeptide of claim 300, wherein, The heavy chain of the fourth structural domain is directly or indirectly connected to the second structural domain.

302. The fusion polypeptide of claim 300, wherein, The light chain of the fourth structural domain is directly or indirectly connected to the second structural domain.

303. The fusion polypeptide according to claims 282-302, wherein, The fourth structural domain is directly or indirectly connected to the third structural domain.

304. The fusion polypeptide of claim 303, wherein, The light chain of the fourth structural domain is directly or indirectly connected to the third structural domain.

305. The fusion polypeptide of claim 303, wherein, The heavy chain of the fourth structural domain is directly or indirectly connected to the third structural domain.

306. The fusion polypeptide according to claims 282-305, wherein, In one embodiment of the fusion polypeptide, the indirect connection comprises a linker.

307. The fusion polypeptide of claim 306, wherein, The linker comprises an amino acid sequence selected from the group shown below: SEQ ID NO: 16-21.

308. The fusion polypeptide according to claims 282-307, wherein, The fusion polypeptide comprises an amino acid sequence selected from SEQ ID NO: 700-708, SEQ ID NO: 725-740, and SEQ ID NO: 745-774.

309. An immunoconjugate comprising an antibody or antigen-binding fragment of any one of claims 1-19, and / or a fusion polypeptide of any one of claims 20-308.

310. A nucleic acid molecule encoding an antibody or antigen-binding fragment as described in any one of claims 1-19, and / or a fusion polypeptide as described in any one of claims 10-322.

311. A carrier comprising the nucleic acid molecule of claim 310.

312. A cell comprising and / or expressing an antibody or antigen-binding fragment of any one of claims 1-19, and / or a fusion polypeptide of any one of claims 20-308, an immunoconjugate of claim 309, a nucleic acid molecule of claim 310, and / or a vector of claim 311.

313. A composition comprising an antibody or antigen-binding fragment of any one of claims 1-19, and / or a fusion polypeptide of any one of claims 20-308, an immunoconjugate of claim 309, a nucleic acid molecule of claim 310, and / or a carrier of claim 311, and / or a cell of claim 312, and optionally a pharmaceutically acceptable carrier.

314. A method for preparing an antibody or antigen-binding fragment of any one of claims 1-19, and / or a fusion polypeptide of any one of claims 20-308, comprising culturing cells according to claim 312 under conditions that enable the fusion polypeptide to be expressed.

315. A method for blocking the interaction between HHLA2 and KIR3DL3, comprising administering an effective amount of an antibody or antigen-binding fragment of any one of claims 1-19, and / or a fusion polypeptide of any one of claims 20-308.

316. A method for inhibiting the growth and / or proliferation of tumors or tumor cells, comprising administering an effective amount of an antibody or antigen-binding fragment of any one of claims 1-19, and / or a fusion polypeptide of any one of claims 20-308, an immunoconjugate of claim 309, a nucleic acid molecule of claim 310, and / or a carrier of claim 311, a cell of claim 312, and / or a composition of claim 313.

317. Use of the antibody or antigen-binding fragment of any one of claims 1-19, and / or the fusion polypeptide of any one of claims 20-308, the immunoconjugate of claim 309, the nucleic acid molecule of claim 310, and / or the carrier of claim 311, the cell of claim 312, and / or the composition of claim 313 in the preparation of a medicament, wherein the medicament is used for the prevention, improvement and / or treatment of tumors.

318. The use according to claim 317, wherein the tumor comprises a solid tumor and / or a hematoma.

319. The use according to any one of claims 318, wherein the tumor is selected from the group consisting of: colon tumors, breast tumors, lung tumors, gastric tumors, melanoma, head and neck tumors, lymphoma, nasopharyngeal tumors, cervical tumors, esophageal tumors, kidney tumors, squamous cell carcinoma of the skin, endometrial tumors, liver tumors, bladder tumors, urothelial tumors, and skin tumors.

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