Bispecific fusion proteins for tumor therapy

Abstract

The present invention relates to the use of a dimer in the preparation of a medicament for treating a tumor in a subject in need thereof, and to a dimer formed from two polypeptide chains, each comprising an antibody Fc subunit. The dimer comprises two or more immunoglobulin single variable domains (ISVDs), at least one of the ISVDs being specific for PD-L1 and at least one of the ISVDs being specific for CTLA4. The present invention also provides a method for treating a tumor in a subject that is resistant to immune checkpoint inhibitor therapy.

Description

[Technical Field]

[0001] The present invention relates to the use of a dimer in the preparation of a medicament for the treatment of a tumor in a subject in need thereof, and to a dimer formed from two polypeptide chains, each comprising an antibody Fc subunit. [Background technology]

[0002] Blockade of PD1 / PD-L1 interaction is expected to enhance tumor-specific T cell immunity, ultimately leading to the elimination of tumor cells by the immune system. Programmed cell death ligand-1 (PD-L1) is expressed on antigen-presenting cells and many human tumor cells, and has been shown to downregulate T cell activation and cytokine secretion upon binding to PD-1.

[0003] Similarly, abrogation of immune regulatory molecules such as cytotoxic T-lymphocyte antigen 4 (CTLA4) is expected to be a new and promising strategy to induce tumor regression and prolong patient survival by manipulating the immune system. Anti-CTLA4 antibodies (e.g., ipilimumab) have also been developed and are commercially available for the treatment of tumors.

[0004] Recently, combination therapies using separate intravenous administration of PD1 / PD-L1 and CTLA4 antibodies have been reported. However, these combination therapies have many drawbacks, including increased patient inconvenience and pain, and the difficulty of manufacturing and characterizing multiple drugs. Furthermore, suboptimal efficacy and safety issues have also been reported. Therefore, there remains an unmet medical need for new promising agents for tumor treatment, especially those capable of simultaneously acting on multiple targets. DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0005] The present disclosure provides use of a dimer comprising two polypeptide chain monomers, each comprising an antibody Fc subunit, in a pharmaceutical preparation for treating a tumor in a subject in need thereof. The dimer comprises two or more immunoglobulin single variable domains (ISVDs), at least one of the ISVDs being specific for PD-L1 and at least one of the ISVDs being specific for CTLA4. The disclosure also provides a method for treating a tumor in a subject in need thereof, the method comprising administering to the subject an effective amount of a dimer, where the subject is resistant to immune checkpoint inhibitor treatment. [Means for solving the problem]

[0006] In one aspect, the disclosure provides use of a dimer in the preparation of a medicament for treating a tumor in a subject in need thereof, said dimer being formed by two polypeptide chains, each of said two polypeptide chains comprising an antibody Fc subunit, said dimer comprising two or more immunoglobulin single variable domains (ISVDs), at least one of said ISVDs being specific for PD-L1 and at least one of said ISVDs being specific for CTLA4.

[0007] In some embodiments, at least one of the two polypeptide chains comprises both a PD-L1-specific ISVD and a CTLA4-specific ISVD.

[0008] In some embodiments, each of the two polypeptide chains comprises both an ISVD specific for PD-L1 and an ISVD specific for CTLA4.

[0009] In some embodiments, for one or both of the two polypeptide chains, the ISVD specific for PD-L1 is fused, optionally via a linker, to the ISVD specific for CTLA4.

[0010] In some embodiments, for one or both of the two polypeptide chains: the ISVD specific for PD-L1 is fused, optionally via a linker, to the ISVD specific for CTLA4; and the ISVD specific for CTLA4 is fused, optionally via a linker, to the antibody Fc subunit.

[0011] In some embodiments, for one or both of the two polypeptide chains: the C-terminus of the ISVD specific for PD-L1 is fused, optionally via a linker, to the N-terminus of the ISVD specific for CTLA4; and the C-terminus of the ISVD specific for CTLA4 is fused, optionally via a linker, to the N-terminus of the antibody Fc subunit.

[0012] In some embodiments, for one or both of the two polypeptide chains: the ISVD specific for PD-L1 is fused, optionally via a linker, to the ISVD specific for CTLA4; and the ISVD specific for PD-L1 is fused, optionally via a linker, to the antibody Fc subunit.

[0013] The C-terminus of the CTLA4-specific ISVD is fused, optionally via a linker, to the N-terminus of the PD-L1-specific ISVD; and the C-terminus of the PD-L1-specific ISVD is fused, optionally via a linker, to the N-terminus of the antibody Fc subunit.

[0014] In some embodiments, the antibody Fc subunit is derived from an IgG Fc subunit.

[0015] In some embodiments, the IgG is human IgG1.

[0016] In some embodiments, the antibody Fc subunit comprises the amino acid sequence set forth in any one of SEQ ID NOs: 35, 38, and 39.

[0017] In some embodiments, the ISVD specific for PD-L1 may bind to the human PD-L1 N-terminal IgV domain.

[0018] In some embodiments, the PD-L1 specific ISVD can bind to residues 154, Y56, E58, Q66, and / or R113 of the human PD-L1 N-terminal IgV domain, and the human PD-L1 N-terminal IgV domain comprises the amino acid sequence set forth in SEQ ID NO:64.

[0019] In some embodiments, the PD-L1-specific ISVD may further bind to residues D61, N63, V68, M115, S117, Y123, and / or R125 of the human PD-L1 N-terminal IgV domain, and the human PD-L1 N-terminal IgV domain comprises the amino acid sequence set forth in SEQ ID NO:64.

[0020] In some embodiments, the PD-L1-specific ISVD can bind to a conformational epitope in the human PD-L1 N-terminal IgV domain, where the conformational epitope comprises residues 154, Y56, E58, Q66, and R113 of the human PD-L1 N-terminal IgV domain, and the human PD-L1 N-terminal IgV domain comprises the amino acid sequence set forth in SEQ ID NO:64.

[0021] In some embodiments, the ISVD specific for PD-L1 can bind to a conformational epitope in the human PD-L1 N-terminal IgV domain, where the conformational epitope comprises residues 154, Y56, E58, Q66, R113, D61, N63, V68, M115, S117, Y123, and R125 of the human PD-L1 N-terminal IgV domain, and the human PD-L1 N-terminal IgV domain comprises the amino acid sequence set forth in SEQ ID NO:64.

[0022] In some embodiments, the ISVD specific for PD-L1 can block the binding of PD-L1 to PD1.

[0023] In some embodiments, the ISVD specific for PD-L1 can block the binding of PD-L1 to CD80.

[0024] In some embodiments, the ISVD specific for PD-L1 competes for binding to PD-L1 with a reference anti-PD-Ll antibody, wherein the reference anti-PD-Ll antibody comprises a heavy chain CDR3 consisting of the amino acid sequence set forth in SEQ ID NO:1.

[0025] In some embodiments, the reference anti-PD-Ll antibody comprises a heavy chain CDR3 consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 5 and 9.

[0026] In some embodiments, the reference anti-PD-Ll antibody comprises a heavy chain CDR1 consisting of the amino acid sequence set forth in SEQ ID NO:2.

[0027] In some embodiments, the reference anti-PD-Ll antibody comprises a heavy chain CDR1 consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 3 and 7.

[0028] In some embodiments, the reference anti-PD-Ll antibody comprises a heavy chain CDR2 consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 4, 8, and 11.

[0029] In some embodiments, the reference anti-PD-L1 antibody is an ISVD specific for PD-L1.

[0030] In some embodiments, the reference anti-PD-Ll antibody comprises a heavy chain variable domain consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 6, 10, 12, 13, 14, and 15.

[0031] In some embodiments, the reference anti-PD-Ll antibody comprises a heavy chain variable domain consisting of the amino acid sequence set forth in SEQ ID NO:6.

[0032] In some embodiments, the ISVD specific for PD-L1 comprises a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO:1.

[0033] In some embodiments, the ISVD specific for PD-L1 comprises a heavy chain consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 5 and 9.

[0034] In some embodiments, the ISVD specific for PD-L1 comprises a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO:2.

[0035] In some embodiments, the ISVD specific for PD-L1 comprises a heavy chain consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 3 and 7.

[0036] In some embodiments, the ISVD specific for PD-L1 comprises a heavy chain consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 4, 8, and 11.

[0037] In some embodiments, the ISVD specific for PD-L1 comprises a heavy chain variable domain consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 6, 10, 12, 13, 14, and 15.

[0038] In some embodiments, the ISVD specific for PD-L1 comprises a heavy chain variable domain consisting of the amino acid sequence set forth in SEQ ID NO:6.

[0039] In some embodiments, the ISVD specific for CTLA4 can specifically bind to human CTLA4.

[0040] In some embodiments, the ISVD specific for CTLA4 is capable of blocking the binding of CTLA4 to CD80.

[0041] In some embodiments, the ISVD specific for CTLA4 is capable of blocking the binding of CTLA4 to CD86.

[0042] In some embodiments, the ISVD specific for CTLA4 cross-competes for binding to CTLA4 with a reference anti-CTLA4 antibody, wherein the reference anti-CTLA4 antibody comprises a heavy chain CDR3 consisting of the amino acid sequence set forth in SEQ ID NO:19.

[0043] In some embodiments, the reference anti-CTLA4 antibody comprises a heavy chain CDR1 consisting of the amino acid sequence set forth in SEQ ID NO:17.

[0044] In some embodiments, the reference anti-CTLA4 antibody comprises a heavy chain CDR2 consisting of the amino acid sequence set forth in SEQ ID NO:16.

[0045] In some embodiments, the reference anti-CTLA4 antibody comprises a heavy chain CDR2 consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 18, 21, and 23.

[0046] In some embodiments, the reference anti-CTLA4 antibody is an ISVD specific for CTLA4.

[0047] In some embodiments, the reference anti-CTLA4 antibody comprises a heavy chain variable domain consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 20, 22, and 24-32.

[0048] In some embodiments, the reference anti-CTLA4 antibody comprises a heavy chain variable domain consisting of the amino acid sequence set forth in SEQ ID NO:20.

[0049] In some embodiments, the ISVD specific for CTLA4 comprises the amino acid sequence set forth in SEQ ID NO:19.

[0050] In some embodiments, the ISVD specific for CTLA4 comprises the amino acid sequence set forth in SEQ ID NO:17.

[0051] In some embodiments, the ISVD specific for CTLA4 comprises the amino acid sequence set forth in SEQ ID NO:16.

[0052] In some embodiments, the ISVD specific for CTLA4 comprises the amino acid sequence set forth in any one of SEQ ID NOs: 18, 21, and 23.

[0053] In some embodiments, the ISVD specific for CTLA4 comprises a heavy chain variable domain consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 20, 22, and 24-32.

[0054] In some embodiments, the ISVD specific for CTLA4 comprises a heavy chain variable domain consisting of the amino acid sequence set forth in SEQ ID NO:20.

[0055] In some embodiments, the dimer is a homodimer.

[0056] In some embodiments, the linker comprises the amino acid sequence set forth in any one of SEQ ID NOs: 33-34.

[0057] In some embodiments, one or both of the two polypeptide chains comprises the amino acid sequence set forth in any one of SEQ ID NOs: 40-43, 46, 48, and 50.

[0058] In some embodiments, one or both of the two polypeptide chains comprises the amino acid sequence set forth in SEQ ID NO:40.

[0059] In some embodiments, the dimer is capable of blocking the binding of PD-L1 to PD-1.

[0060] In some embodiments, the dimer is capable of blocking the binding of PD-L1 to CD80.

[0061] In some embodiments, the dimer is capable of blocking the binding of CTLA4 to CD80.

[0062] In some embodiments, the dimer is capable of blocking the binding of CTLA4 to CD86.

[0063] In some embodiments, the tumor is selected from the group consisting of NSCLC, melanoma, esophageal squamous cell carcinoma (ESCC), NPC, and breast cancer.

[0064] In some embodiments, the tumor is selected from the group consisting of esophageal squamous cell carcinoma (ESCC) and nasopharyngeal carcinoma (NPC).

[0065] In some embodiments, the subject is administered an immune checkpoint inhibitor.

[0066] In some embodiments, the subject has substantially failed to respond to the immune checkpoint inhibitor.

[0067] In some embodiments, the immune checkpoint inhibitor is selected from the group consisting of: a PD-L1 inhibitor, a PD-1 inhibitor, and a CTLA4 inhibitor.

[0068] In some embodiments, the subject is administered chemotherapy, chemoradiotherapy, CTL cell therapy, EGFR tyrosine kinase inhibitors (TKIs), and / or anti-angiogenic drugs.

[0069] In some embodiments, the chemotherapy comprises first-line chemotherapy and / or second-line chemotherapy.

[0070] In some embodiments, the second line chemotherapy comprises paclitaxel, docetaxel, capecitabine and / or 5-FU.

[0071] In some embodiments, the tumor is selected from the group consisting of locally advanced or metastatic melanoma, non-keratinizing locally advanced recurrent or metastatic NPC, metastatic NSCLC, squamous and non-squamous NSCLC, recurrent or metastatic ESCC, and triple-negative breast cancer (TNBC).

[0072] In some embodiments, the tumor is selected from the group consisting of advanced NSCLC without EGFR mutations or ALK fusions, NSCLC with EGFR exon 20 insertion mutations, PD-L1 positive NPC, and locally advanced inoperable or metastatic TNBC.

[0073] In some embodiments, the dimer is administered in combination with a chemotherapeutic agent.

[0074] In some embodiments, the chemotherapeutic agent comprises a platinum agent and / or paclitaxel.

[0075] In some embodiments, the chemotherapeutic agents include cisplatin, gemcitabine, and / or nab-paclitaxel.

[0076] In another aspect, the present disclosure provides a method of treating a tumor in a subject in need thereof, comprising administering to the subject an effective amount of a dimer of the present disclosure.

[0077] In some embodiments, the tumor is selected from the group consisting of NSCLC, melanoma, esophageal squamous cell carcinoma (ESCC), NPC, and breast cancer.

[0078] In some embodiments, the tumor is selected from the group consisting of esophageal squamous cell carcinoma (ESCC) and nasopharyngeal carcinoma (NPC).

[0079] In some embodiments, the subject is administered an immune checkpoint inhibitor.

[0080] In some embodiments, the subject has substantially failed to respond to the immune checkpoint inhibitor.

[0081] In some embodiments, the immune checkpoint inhibitor is selected from the group consisting of: a PD-L1 inhibitor, a PD-1 inhibitor, and a CTLA4 inhibitor.

[0082] In some embodiments, the subject is administered chemotherapy, chemoradiotherapy, CTL cell therapy, EGFR tyrosine kinase inhibitors (TKIs), and / or anti-angiogenic drugs.

[0083] In some embodiments, the chemotherapy comprises first-line chemotherapy and / or second-line chemotherapy.

[0084] In some embodiments, the second line chemotherapy comprises paclitaxel, docetaxel, capecitabine and / or 5-FU.

[0085] In some embodiments, the tumor is selected from the group consisting of advanced NSCLC without EGFR mutations or ALK fusions, NSCLC with EGFR exon 20 insertion mutations, PD-L1 positive NPC, and locally advanced inoperable or metastatic TNBC.

[0086] In some embodiments, the dimer is administered in combination with a chemotherapeutic agent.

[0087] In some embodiments, the chemotherapeutic agent comprises a platinum agent and / or paclitaxel.

[0088] In some embodiments, the chemotherapeutic agent comprises cisplatin, gemcitabine, and / or a platinum agent.

[0089] In some embodiments, the dose of the dimer is between 1 mg / kg and 5 mg / kg.

[0090] In some embodiments, the dose of the dimer is between 1 mg / kg and 3 mg / kg.

[0091] In some embodiments, the dose of the dimer is between 3 mg / kg and 5 mg / kg.

[0092] In some embodiments, the dimer is administered once every two weeks or once every three weeks.

[0093] In some embodiments, the dimer is administered by intravenous administration.

[0094] In another aspect, the present disclosure provides for the use of a dimer of the present disclosure in combination with a platinum drug of the present disclosure in the preparation of a medicament for treating a tumor in a subject in need thereof.

[0095] In some embodiments, the tumor is selected from the group consisting of a solid tumor and a hematological tumor.

[0096] In some embodiments, the tumor comprises NSCLC and / or breast cancer.

[0097] In some embodiments, the subject is administered EGFR tyrosine kinase inhibitors (TKIs).

[0098] In some embodiments, the tumor is selected from the group consisting of squamous and non-squamous NSCLC and triple-negative breast cancer (TNBC).

[0099] In some embodiments, the tumor is selected from the group consisting of NSCLC with EGFR exon 20 insertion mutations and locally advanced inoperable or metastatic TNBC.

[0100] In some embodiments, the dimer is administered at a dosing frequency of 4 times per week, 2 times per week, once per week, once every 2 weeks, once every 3 weeks, once every 4 weeks, once every 5 weeks, once every 6 weeks, once every 8 weeks, or once every 12 weeks.

[0101] In some embodiments, the platinum agent is administered at a dosing frequency of 4 times per week, 2 times per week, once per week, once every 2 weeks, once every 3 weeks, once every 4 weeks, once every 5 weeks, once every 6 weeks, once every 8 weeks, or once every 12 weeks.

[0102] In some embodiments, the dimer is administered intravenously, intramuscularly, subcutaneously, topically, orally, transdermally, intraperitoneally, intraorbitally, by implantation, by inhalation, intrathecally, intracerebroventricularly, or intranasally.

[0103] In some embodiments, the platinum agent is administered intravenously, intramuscularly, subcutaneously, topically, orally, transdermally, intraperitoneally, intraorbitally, by implantation, by inhalation, intrathecally, intracerebroventricularly, or intranasally.

[0104] In some embodiments, the dimer is administered at a dose of 0.01 mg / kg to 100 mg / kg.

[0105] In some embodiments, the chemotherapeutic agent is administered at a dose of 0.01 mg / kg to 100 mg / kg.

[0106] In another aspect, the present disclosure provides a kit comprising a dimer of the present disclosure in combination with a chemotherapeutic agent of the present disclosure.

[0107] Further aspects and advantages of the present disclosure will become readily apparent to those skilled in the art from the following detailed description. Only exemplary embodiments of the present disclosure are shown and described herein. As will be understood, the present disclosure is capable of other and different embodiments, and its several details are capable of modification in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. [Effects of the Invention]

[0108] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. [Brief explanation of the drawings]

[0109] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are employed, and the accompanying drawings (also referred to herein as "FIG" and "FIG.").

[0110] [Figure 1] 1 shows an example of a dimer of the present disclosure. [Figure 2] An overview of efficacy in a phase I study in patients with solid tumors is shown in Figure 2. [Figure 3] Showing changes in target lesions from baseline using the disclosed dimers DETAILED DESCRIPTION OF THE INVENTION

[0111] While various embodiments of the present invention have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions may occur to those skilled in the art without departing from the invention. It is understood that various alternatives to the embodiments of the invention described herein may be used.

[0112] As used herein, the terms "homology," "homologous," or "sequence identity" generally refer to sequence similarity or interchangeability between two or more polynucleotide sequences or two or more polypeptide sequences. When using a program (e.g., Emboss Needle or BestFit) to determine sequence identity, similarity, or homology between two different amino acid sequences, default settings may be used, or an appropriate scoring matrix, such as blosum 45 or blosum 80, may be selected to optimize the identity, similarity, or homology score. In some embodiments, homologous polynucleotides are those that hybridize under stringent conditions and have at least 60%, at least 65%, at least 70%, at least 80%, at least 90%, at least 95%, at least 97%, at least 98%, at least 99%, and 100% sequence identity with a reference sequence. Homologous polypeptides may have at least 80%, at least 90%, or at least 95%, or at least 97%, or at least 98%, or at least 99% sequence identity with each other when sequences of comparable lengths are optimally aligned.

[0113] The term "percent (%) sequence identity," when used in the context of the polypeptide sequences identified herein, generally refers to the percentage of amino acid residues or nucleotides in a query sequence that are identical to the amino acid residues or nucleotides of a second reference polypeptide sequence, or portion thereof, after aligning the sequences, optionally introducing gaps to achieve the maximum percent sequence identity, and not considering conservative substitutions as part of the sequence identity. Alignment for purposes of determining percent amino acid / nucleotide sequence identity can be achieved in a variety of ways within the skill of those in the art, for example, using publicly available computer software such as BLAST, BLAST-2, ALIGN, NEEDLE, or Megalign (DNASTAR) software. Those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithms necessary to achieve maximal alignment over the full length of the sequences being compared.

[0114] Percent identity can be measured over the length of the entire defined polypeptide / polynucleotide sequence, or over a shorter length, for example, over the length of a fragment taken from a larger defined polypeptide / polynucleotide sequence. It is understood that in tables, figures, or sequence listings, any fragment length supported by the sequences set forth herein can be used to describe the length over which percentage identity can be measured.

[0115] The term "bispecific antibody" as used herein generally refers to an antibody that has the ability to bind to two different epitopes, either on a single antigen or on two different antigens.

[0116] As used herein, the term "PD-L1" generally refers to the programmed death ligand 1 protein, its functional variants, and / or functional fragments. PD-L1, also known as cluster of differentiation 274 (CD274) or B7 homolog 1 (B7-H1), is a protein encoded by the CD274 gene (in humans). PD-L1 binds to its receptor, programmed cell death protein 1 (PD-1), which is expressed on activated T cells, B cells, and macrophages (Ishida et al., 1992 EMBO J, 11:3887-3395; Okazaki et al., Autoimmune dilated cardiomyopathy in PD-1 receptor-deficient mice). Science. 2001;291:(319-22). The complexation of PD-L1 and PD-1 exerts an immunosuppressive effect by inhibiting T cell proliferation and the cytokine production of IL-2 and IFN-γ (Freeman et al., Engagement of PD-1 immunoinhibitory receptor by a novel B7 family member leads to negative regulation of lymphocyte activation, J. Exp. Med. 2000, 192:1027-1034; Carter et al., The PD-1:PD-L inhibitory pathway affects both CD4(+) and CD8(+) T cells and is overcome by IL-2, Eur. J. ImmunoL 2002, 32:634-643). For example, the term "PD-L1" can include a polypeptide or fragment thereof that has at least about 85% amino acid sequence identity to NCBI Accession No. Q9NZQ7 and specifically binds to PD1. The term "PD-L1" includes the entire PD-L1 ligand, soluble PD-L1 ligand, and fusion proteins that include a functionally active portion of the PD-L1 ligand covalently linked to a second moiety, e.g., a protein domain.The definition of PD-L1 also includes variants that differ in amino acid sequence from naturally occurring PD-L1 but retain the ability to specifically bind to the PD1 receptor. Furthermore, the definition of PD-L1 also includes variants that enhance the biological activity of PD1. PD-L1 sequences are known in the art and are provided, for example, in GenBank Accession Number 29126. As used herein, the term "PD-L1" includes human PD-L1 (hPD-L1), variants, isoforms, and species homologs of hPD-L1, as well as analogs that share at least one epitope with hPD-L1. For example, the term "PD-L1" also includes PD-L1 from other mammalian species, such as rat, mouse, rabbit, non-human primate, pig, or cow. The complete hPD-L1 sequence is provided in GenBank Accession No. 29126.

[0117] As used herein, the term "human PD-L1 N-terminal IgV domain" generally refers to the extracellular domain of human PD-L1 located at its N-terminus. The term "human PD-L1 N-terminal IgV domain" may also refer to an epitope within that domain. The N-terminal IgV domain of the human PD-L1 protein (including the signal peptide) may comprise the amino acid sequence set forth in SEQ ID NO:64.

[0118] As used herein, the term "CTLA4" generally refers to cytotoxic T-lymphocyte-associated protein 4, its functional variants, and / or functional fragments. CTLA4 is an immunoinhibitory receptor belonging to the CD28 family. CTLA4 is expressed exclusively on T cells (CD4+ and CD8+ cells) in vivo and binds to two ligands, CD80 and CD86 (also known as "B7-1" and "B7-2"). For example, the term "CTLA4" can include a polypeptide or fragment thereof that has at least about 85% amino acid sequence identity with NCBI Accession No. AAL07473.1 and specifically binds to CD80 and / or CD86. The term "CTLA4" includes the entire CTLA4 receptor, its extracellular domain, and fusion proteins containing a functionally active portion of CTLA4 covalently linked to a second portion, e.g., a protein domain. The definition of CTLA4 also includes variants that differ in amino acid sequence from naturally occurring CTLA4 but retain the ability to specifically bind to the ligands CD80 and / or CD86. CTLA4 sequences are known in the art and are provided, for example, in GenBank Accession Number 1493. As used herein, the term "CTLA4" includes human CTLA4 (hCTLA4), variants, isoforms, and species homologs of hCTLA4, as well as analogs that share at least one epitope with hCTLA4. For example, the term "CTLA4" also includes CTLA4 from other mammals, such as rat, mouse, rabbit, non-human primate, pig, or cow. The complete hCTLA4 sequence is provided in GenBank Accession No. 1493.

[0119] As used herein, the term "antibody Fc subunit" generally refers to a component of an antibody Fc domain. For example, an antibody Fc domain can be formed by two or more members, and each member can be considered an Fc subunit. As used herein, the term "Fc domain" generally refers to the Fc portion or Fc fragment of an antibody heavy chain. For example, it can refer to the carboxyl-terminal portion of an immunoglobulin heavy chain constant region, or an analog or portion thereof capable of binding to an Fc receptor. As is known, each immunoglobulin heavy chain constant region contains four or five domains. The domains are sequentially named as follows: CH1-hinge-CH2-CH3(-CH4). CH4 is present in IgM, which does not have a hinge region. An Fc domain or Fc subunit useful in the present disclosure can include a CH3 domain. For example, an Fc domain or Fc subunit can include a CH2 domain and a CH3 domain. In some embodiments, an Fc domain or Fc subunit can also include an immunoglobulin hinge region. For example, an Fc domain or Fc subunit may comprise or consist, from N- to C-terminus, of a CH2 domain and a CH3 domain. In another example, an Fc domain or Fc subunit may comprise or consist, from N- to C-terminus, of an immunoglobulin hinge region, a CH2 domain, and a CH3 domain. The positions of amino acid residues within an Fc domain or Fc subunit can be determined according to Kabat, EA et al. (1991) Sequences of Proteins of Immunological Interest, 5th ed., NIH Publication No. 91-3242.

[0120] As used herein, the term "Fc domain" generally refers to the C-terminal region of an immunoglobulin heavy chain, including native-sequence Fc regions and variant Fc regions. Although the boundaries of the Fc region of an immunoglobulin heavy chain can vary, the human IgG heavy chain Fc region is usually defined to stretch from the amino acid residue at position Cys226, or from Pro230, to its carboxyl terminus. The C-terminal lysine of the Fc region (residue 447 according to the EU numbering system) can be removed, for example, during antibody production or purification, or by recombinantly engineering the nucleic acid encoding the antibody heavy chain. Thus, a complete antibody composition can include antibody populations in which all K447 residues have been removed, antibody populations in which the K447 residue has not been removed, and antibody populations having a mixture of antibodies with and without the K447 residue. Suitable native-sequence Fc regions for use in the antibodies of the present invention include human IgG1, IgG2 (IgG2A, IgG2B), IgG3, and IgG4.

[0121] Unless otherwise indicated herein, the numbering of residues in immunoglobulin chains is that of the EU index in Kabat et al., Sequences of Proteins of Immunological Interest, Public Health Service, National Institutes of Health, Bethesda, Md. (1991). "EU index as in Kabat" refers to the residue numbering of the human IgG1 EU antibody.

[0122] As used herein, the term "dimer" generally refers to a macromolecular complex formed by two, usually non-covalently linked, monomeric units. Each monomeric unit can be a polymer, such as a polypeptide chain or a polynucleotide. As used herein, the term "homodimer" generally refers to a dimer composed of or formed by two substantially identical monomers, such as two substantially identical polypeptide chains. In some cases, the two monomers of a homodimer may differ in one or more regions or positions, but such differences do not significantly alter the function or structure of the monomers. For example, one of skill in the art would consider the difference between the two monomers to have little or no biological and / or statistical significance in the context of the biological properties considered in this disclosure. The structural / compositional difference between the two monomers may be, for example, less than about 50%, less than about 40%, less than about 30%, less than about 20%, less than about 10%, less than about 5%, or even less.

[0123] As used herein, the term "fusion" or "fusion" generally refers to a covalent bond between two polypeptides. The polypeptides are typically linked to each other directly via a peptide bond or via an amino acid linker. Optionally, the peptides can be linked via non-peptide covalent bonds known to those skilled in the art.

[0124] The term "fusion protein," as used herein, generally refers to a polypeptide that comprises or consists of the amino acid sequence of a polypeptide fused directly or indirectly (e.g., via a linker) to the amino acid sequence of a heterologous polypeptide (i.e., a polypeptide unrelated to the former polypeptide or a domain thereof).

[0125] The term "immunoglobulin single variable domain (ISVD)" as used herein generally refers to an antigen-binding domain or a VHH domain or a fragment thereof, such as a VH or VL domain, respectively. The terms "antigen-binding molecule" and "antigen-binding protein" are used interchangeably, and also include the term "nanobody." Immunoglobulin single variable domains can further be light chain variable domain sequences (e.g., VL sequences) or heavy chain variable domain sequences (e.g., VH sequences). More specifically, they can be heavy chain variable domain sequences derived from a conventional four-chain antibody or heavy chain variable domain sequences derived from a heavy-chain antibody. Thus, immunoglobulin single variable domains can be domain antibodies, or immunoglobulin sequences suitable for use as domain antibodies, single domain antibodies, single domain antibodies, or immunoglobulin sequences suitable for use as single domain antibodies, "dAbs," or immunoglobulin sequences suitable for use as dAbs, or nanobodies, including, but not limited to, VHH sequences. Immunoglobulin single variable domains include fully humanized, otherwise sequence-optimized, or chimeric immunoglobulin sequences. Immunoglobulin single variable domains and the structure of immunoglobulin single variable domains can be considered to be composed of, but not limited to, four framework regions or "FRs" referred to in the art and herein as "framework region 1" or "FR1"; "framework region 2" or "FR2"; "framework region 3" or "FR3"; and "framework region 4" or "FR4", which framework regions are interrupted by three complementarity-determining regions or "CDRs" referred to in the art as "complementarity-determining region 1" or "CDR1"; "complementarity-determining region 2" or "CDR2"; and "complementarity-determining region 3" or "CDR3".

[0126] As used herein, the term "humanized" generally refers to an antibody or fragment thereof in which some, most, or all of the amino acids outside the CDR domains of a non-human antibody have been replaced with corresponding amino acids from a human immunoglobulin. For example, in a humanized form of an antibody, some, most, or all of the amino acids outside the CDR domains have been replaced with amino acids from a human immunoglobulin, while some, most, or all of the amino acids within one or more CDR regions remain unchanged. Minor additions, deletions, insertions, substitutions, or modifications of amino acids are permissible as long as they do not interfere with the ability of the antibody to bind to its specific antigen / epitope. A humanized antibody may retain antigen specificity similar to that of the original antibody.

[0127] As used herein, the term "epitope" or "antigenic determinant" generally refers to a site on an antigen to which an antibody binds. Epitopes can be formed from contiguous amino acids (linear epitopes) or from non-contiguous amino acids juxtaposed by tertiary folding of a protein (conformational epitopes). Epitopes formed from contiguous amino acids are typically retained upon exposure to denaturing solvents, whereas epitopes formed by tertiary folding are typically lost upon treatment with denaturing solvents. An epitope typically contains at least three, more commonly at least five or 8-10, amino acids in a unique spatial conformation. Methods for determining the spatial conformation of epitopes include, for example, X-ray crystallography and two-dimensional nuclear magnetic resonance. See, for example, Epitope Mapping Protocols in Methods in Molecular Biology, Vol. 66, Glenn E. Morris, Ed. (1996).

[0128] As used herein, the term "conformational epitope" generally refers to non-contiguous amino acid residues of an antigen (such as the PD-L1 antigen) that are juxtaposed by tertiary folding of the protein. These non-contiguous amino acid residues may come together on the surface when the polypeptide chain folds to form the native protein. Conformational epitopes include, but are not limited to, functional epitopes.

[0129] As used herein, the term "functional epitope" generally refers to amino acid residues of an antigen that contribute energetically to antibody binding, i.e., form an "energy epitope." Mutation of any one of the energetically contributing residues of an antigen to alanine disrupts antibody binding, resulting in an antibody relative KD ratio (KD mutant / KD wild-type) that can be, for example, 3-fold or more, 4-fold or more, 6-fold or more, 10-fold or more, 20-fold or more, 30-fold or more, 40-fold or more, 50-fold or more, 60-fold or more, 70-fold or more, 80-fold or more, 90-fold or more, 100-fold or more, 150-fold or more, 200-fold or more, or more.

[0130] As used herein, the term "extracellular domain" generally refers to a portion of a protein (e.g., a membrane protein such as a receptor) that protrudes from the outer membrane of a cellular organelle and / or cell. The extracellular domain consists of loops that intertwine with the membrane as the polypeptide chain passes through the bilayer multiple times. The extracellular domain can recognize and respond to specific ligands.

[0131] The term "linker," as used herein, generally refers to a synthetic amino acid sequence that links or connects two polypeptide sequences, e.g., connects two polypeptide domains. The linker can connect two amino acid sequences via a peptide bond. In some embodiments, the linkers of the present disclosure connect a biologically active moiety to a second moiety in a linear sequence. For example, peptide linkers can be non-immunogenic and flexible, such as those containing serine and glycine sequences or Ala-Ala-Ala repeats. Depending on the particular construct of the dimer, the peptide linker can contain, for example, 3 to 30 (at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 11, at least 17, at least 18, at least 10, at least 21, at least 12, at least 13, at least 14, at least 15, at least 25, at least 16, at least 28, at least 19, at least 20, at least 22, at least 23, at least 24, at least 26, at least 27, at least 29, at least 30) amino acid residues.

[0132] As used herein, the term "N-terminus" is used interchangeably with "N-terminus" and generally refers to the amino terminus / end of a polypeptide chain.

[0133] As used herein, the term "C-terminus" is used interchangeably with "C-terminus" and generally refers to the carboxyl terminus / end of a polypeptide chain.

[0134] The term "tumor" as used herein generally refers to clinically measurable tumor growth or metastasis. Tumors include solid tumors, hematological tumors, lymphomas, and the like. For example, the tumor may be selected from lung cancer (such as non-small cell lung cancer), breast cancer (such as triple-negative breast cancer), kidney cancer (such as renal cell carcinoma), melanoma, cervical cancer, uterine cancer, pancreatic cancer, peritoneal cancer, ovarian cancer, and colon cancer. The tumor is an advanced or metastatic tumor. The tumor may be selected from the group consisting of NSCLC, melanoma, esophageal squamous cell carcinoma (ESCC), NPC, and breast cancer (e.g., triple-negative breast cancer (TNBC)).

[0135] As used herein, the term "subject" generally refers to a human or non-human animal, including, but not limited to, a cat, dog, horse, pig, cow, sheep, goat, rabbit, mouse, rat, or monkey. In some embodiments, the subject is a human. In some embodiments, the subject is resistant to immune checkpoint inhibitor treatment.

[0136] As used herein, the term "about" generally refers to variations within normal tolerances in the art, generally within ±10%, e.g., 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from the context, all numerical values ​​provided herein are modified by the term about.

[0137] As used herein, the terms "combination," "coadministration," or "co-administering" generally refer to the administration of one agent (e.g., a dimer) with another agent (e.g., an immune checkpoint inhibitor). The administration of one agent can be as one single formulation or as two separate formulations (e.g., one for the dimer and one for the immune checkpoint inhibitor). Co-administration can be simultaneous or sequential in either order.

[0138] As used herein, the term "treating" generally refers to having a therapeutic effect and, at least in part, alleviating or eliminating an abnormal condition in an organism. The term "therapy" refers to improving the symptoms of a drug condition as compared to a control group not administered the drug in a group of patients to whom the drug is administered. The effects of treatment can be monitored by measuring changes or non-changes in cell phenotype changes, cell proliferation changes or non-changes, tumor size changes or non-changes, tumor size changes or non-changes, progressive disease changes or non-changes, stable disease changes or non-changes, disease control rate changes or non-changes, partial response changes or non-changes. The term "treating" or "therapy" does not necessarily refer to a complete cure. Reducing even slightly the undesirable symptoms of a disease or slowing the progression of a disease is considered treatment. Further, treatment may include actions that worsen the overall sense of health or appearance of a patient.

[0139] As used herein, the term "specifically binds" or "is specific" generally refers to a measurable and reproducible interaction such as the binding between a target and an antibody, which determines the presence of the target in the presence of a heterogeneous population of molecules including biological molecules. For example, an antibody that specifically binds to a target (which may be an epitope) is an antibody that binds to this target with higher affinity, binding force, more readily, and / or for a longer duration than it binds to other targets. In one embodiment, the degree of binding of the antibody to non-related targets is less than about 10% of the binding of the antibody to the target, as measured, for example, by radioimmunoassay (RIA). In certain embodiments, an antibody that specifically binds to a target has a dissociation constant (KD) of <1x10-6M, <1x10-7M, <1x10-8M, <1x10-9M, or <lx10-10M. In certain embodiments, the antibody specifically binds to an epitope on a protein that is conserved among proteins from different species. In another embodiment, specific binding can include exclusive binding, but exclusive binding is not required.

[0140] As used herein, the term "antibody" generally refers to an immunoglobulin or a fragment or derivative thereof, and includes any polypeptide comprising an antigen-binding site, whether produced in vitro or in vivo. This term includes, but is not limited to, polyclonal antibodies, monoclonal antibodies, monospecific antibodies, polyspecific antibodies, nonspecific antibodies, humanized antibodies, single-chain antibodies, chimeric antibodies, synthetic antibodies, recombinant antibodies, hybrid antibodies, mutated antibodies, and grafted antibodies. For purposes of this disclosure, like "intact antibodies," the term "antibody," unless otherwise modified, also includes antibody fragments such as Fab, F(ab'), Fv, scFv, Fd, dAb, etc., that retain antigen-binding function, i.e., the ability to specifically bind, for example, to CTLA-4 or PD-L1. Typically, such fragments contain the antigen-binding domain.

[0141] The basic four-chain antibody unit is a heterotetrameric glycoprotein consisting of two identical light chains (L) and two identical heavy chains (H). IgM antibodies consist of five basic heterotetrameric units and an additional polypeptide called the J chain, which contains 10 antigen-binding sites. IgA antibodies consist of two to five basic four-chain units, which polymerize and associate with the J chain to form multivalent aggregates. In the case of IgG, the four-chain unit is generally approximately 150,000 daltons. Each L chain is linked to an H chain by a single covalent disulfide bond, while the two H chains are linked to each other by one or more disulfide bonds depending on the H chain isotype. H and L chains each have regularly spaced intrachain disulfide bonds (SS). H chains have a variable domain (VH) at their N-terminus, while the α and γ chains each have three constant domains (CH), and μ and ε have four CH domains. L chains have a variable domain (VL) at their N-terminus and a constant domain (CH) at their other end. The VL aligns with the VH, and the CL aligns with the first constant domain (CHI) of the heavy chain. Certain amino acid residues are thought to form an interface between the light-chain variable domain and the heavy-chain variable domain. The pairing of VH and VL forms an antigen-binding site. For the structure and properties of different classes of antibodies, see, for example, Basic and Clinical Immunology, 8th Edition, Daniel P. Sties, Abba I. Terr, and Tristram G. Parsolw (eds), Appleton & Lange, Norwalk, Conn., 1994, page 71 and Chapter 6. Based on the amino acid sequence of the constant domain, light chains of vertebrate species are classified into one of two clearly distinct types, kappa and lambda. Depending on the amino acid sequence of the constant domain of the heavy chain (CH), immunoglobulins are assigned to different classes or isotypes. Immunoglobulins are classified into five classes. IgA, IgD, IgE, IgG, and IgM have heavy chains designated α, δ, ε, γ, and μ, respectively.The y and a classes are further divided into subclasses based on relatively minor differences in CH sequence and function, for example, humans express the following subclasses: IgG1, IgG2A, IgG2B, IgG3, IgG4, IgA1 and IgK1.

[0142] As used herein, the term "polypeptide chain" generally refers to a polymer comprising two or more covalently linked peptides. The peptides within a polypeptide chain may be linked to each other via peptide bonds. Each polypeptide chain may contain one N-terminus, or amino-terminus, and one C-terminus, or carboxy-terminus.

[0143] As used herein, the term "CD80" generally refers to the ligand for CD28 / CTLA4, also known as B7.1, its functional variants, and / or functional fragments. CD80 is typically expressed on the surface of professional antigen-presenting cells (APCs). For example, the term "CD80" can include polypeptides or fragments thereof that have at least about 85% amino acid sequence identity to NCBI Accession Number P33681 and specifically bind to CTLA4. The definition of CD80 also includes variants that differ in amino acid sequence from naturally occurring CD80 but retain the ability to specifically bind to CTLA4. Also included within the definition of CD80 are variants that enhance the biological activity of CTLA4. CD80 sequences are known in the art and are provided, for example, in GenBank Accession Number P33681. As used herein, the term "CD80" includes human CD80 (hCD80), variants, isoforms, and species homologs of hCD80, as well as analogs that share at least one shared epitope with hCD80. For example, the term "CD80" also includes CD80 from other mammals, e.g., other species, such as rat, mouse, rabbit, non-human primate, pig, or cow. The complete hCD80 sequence is set forth in GenBank Accession No. P 33681.

[0144] As used herein, the term "CD86" generally refers to the ligand for CD28 / CTLA4, also known as B7.2, its functional variants, and / or functional fragments. CD86 is typically expressed on the surface of professional antigen-presenting cells (APCs). For example, the term "CD86" can include a polypeptide or fragment thereof that has at least about 85% amino acid sequence identity to NCBI Accession No. P42081 and specifically binds to CTLA4. The definition of CD86 also includes variants that differ in amino acid sequence from naturally occurring CD86 but retain the ability to specifically bind to CTLA4. Also included within the definition of CD86 are variants that enhance the biological activity of CTLA4. CD86 sequences are known in the art and are provided, for example, in GenBank Accession Number U04343. As used herein, the term "CD86" includes human CD86 (hCD86), variants, isoforms, and species homologs of hCD86, as well as analogs that share at least one shared epitope with hCD86. For example, the term "CD86" also includes CD86 from other mammals, e.g., other species such as rat, mouse, rabbit, non-human primate, pig, or cow. The complete hCD86 sequence can be found under GenBank Accession No. U 04343.

[0145] As used herein, the term "PD1" generally refers to the programmed death-1 receptor, also known as CD279, its functional variants, and / or functional fragments. PD1 is generally expressed on T cells, B cells, natural killer T cells, activated monocytes, and dendritic cells (DCs). PD1 can bind to its ligands, PD-L1 and PD-L2. For example, the term "PD1" can include a polypeptide or fragment thereof that has at least about 85% amino acid sequence identity to NCBI Accession Number P42081 and specifically binds to PD-L1. The definition of PD1 also includes variants that differ in amino acid sequence from naturally occurring PD1 but retain the ability to specifically bind to PD-L1. Also included within the definition of PD1 are variants that enhance the biological activity of PD-L1. PD1 sequences are known in the art and are provided, for example, in GenBank Accession Number Q15116.3. As used herein, the term "PD1" includes human PD1 (hPD1), variants, isoforms, and species homologs of hPD1, as well as analogs that share at least one epitope with hPD1. For example, the term "PD1" also includes PD1 from other species, such as rat, mouse, rabbit, non-human primate, pig, or cow. The complete hPD1 sequence is available in GenBank Accession No. Q 151163.

[0146] As used herein, the term "blocking" generally refers to the inhibition or reduction of binding activity between a molecule and its specific binding partner, for example, between a ligand and its specific receptor.

[0147] As used herein, the terms "blocking antibody" and "antagonist antibody" are used interchangeably and generally refer to an antibody that inhibits or reduces the biological activity of an antigen to which it binds. In some embodiments, a blocking antibody or antagonistic antibody substantially or completely inhibits the biological activity of an antigen. A PD-L1-specific ISVD or a CTLA4-specific ISVD of the present disclosure can be a blocking or antagonistic ISVD. For example, a PD-L1-specific ISVD of the present disclosure can block the interaction between PD-L1 and its receptor PD-1, and thus signaling through PD-1, to restore functional responses to antigen stimulation by T cells from a dysfunctional state. A CTLA4-specific ISVD of the present disclosure can block the interaction between CTLA4 and CD 80 / CD 86, and thus signaling through CTLA4, to restore functional responses to antigen stimulation by T cells from a dysfunctional state.

[0148] As used herein, the terms "cross-competitor for binding," "cross-compete," "cross-blocking," "cross-blocking," and "cross-inhibition" are used interchangeably and generally refer to the ability of an antibody or fragment thereof to directly or indirectly interfere with the binding of another antibody of the invention (e.g., a PD-L1-specific ISVD or CTLA4-specific ISVD of the disclosure) to its target / antigen (e.g., PD-L1 or CTLA4, respectively) through allosteric modulation. The extent to which an antibody or fragment thereof can interfere with the binding of another to its target, and therefore whether it can be said to cross-block or cross-compete in accordance with the present invention, can be determined using competitive binding assays. One particularly suitable quantitative cross-competition assay uses a FACS- or AlphaScreen-based approach to measure competition between a labeled (e.g., His-tagged, biotinylated, or radiolabeled) antibody or fragment thereof and another antibody or fragment thereof for their binding to the target. Generally, a cross-competing antibody or fragment thereof is one that binds to a target in a cross-competition assay, e.g., such that in the assay and in the presence of a second antibody or fragment thereof, the recorded displacement of an immunoglobulin single variable domain or polypeptide according to the invention is up to 100% (e.g., a FACS-based competition assay) of the maximum theoretical displacement by the potentially cross-blocking antibody or fragment thereof to be tested, present in a given amount (e.g., displacement by a cold (e.g., unlabeled) antibody or fragment thereof that needs to cross-block). Preferably, the cross-competing antibody or fragment thereof has a recorded displacement of between 10% and 100%, for example 50% and 100%.

[0149] As used herein, the terms "substantially reduced" or "substantially different" generally refer to a sufficiently high degree of difference between two numerical values ​​(typically one associated with a molecule and one associated with a reference / comparator molecule) such that one of skill in the art would consider the difference between the two values ​​to be statistically significant in the context of the biological property measured by said values ​​(e.g., KD values). The difference between the two values ​​may be, for example, greater than about 10%, greater than about 20%, greater than about 30%, greater than about 40%, and / or greater than about 50% as a function of the value for the reference / comparator molecule.

[0150] As used herein, the terms "substantially similar" or "substantially identical" generally refer to a sufficiently high degree of similarity between two numerical values ​​(e.g., one associated with a molecule of the present disclosure and the other associated with a reference / comparator molecule) such that one of skill in the art would consider the difference between the two values ​​to have little or no biological and / or statistical significance within the context of the biological property measured by the values ​​(e.g., KD values). The difference between the two values ​​is, for example, less than about 50%, less than about 40%, less than about 30%, less than about 20%, and / or less than about 10% as a function of the reference / comparator value.

[0151] As used herein, the term "variable region" or "variable domain" of an antibody generally refers to the amino-terminal domains of the heavy or light chain of an antibody. The variable domains of the heavy and light chains may be referred to as "VH" and "VL," respectively. These domains are generally the most variable parts of an antibody (relative to other antibodies of the same class) and contain the antigen-binding site.

[0152] The term "variable" as used herein generally refers to the fact that certain segments of the variable domains differ extensively in sequence among antibodies. The V domains mediate antigen binding and define the specificity of a particular antibody for a particular antigen. However, variability is not uniformly distributed across the entire span of the variable region. Instead, it is concentrated in three segments called hypervariable regions (CDRs or HVRs) in both the light-chain and heavy-chain variable domains. The more highly conserved portions of the variable domains are called framework regions (FRs). Naturally occurring heavy-chain and light-chain variable domains each contain four FR regions, largely adopting a β-sheet structure, connected by three CDRs to form loops that connect and, in some cases, form part of the β-sheet structure. The CDRs in each chain are held together in close proximity by the FR regions and, with the CDRs from the other chain, contribute to the formation of the antigen-binding site of antibodies (see Kabat et al., Sequences of Immunological Interest, Fifth Edition, National Institutes of Health, Bethesda, Md. (1991)). The constant domains are not directly involved in binding the antibody to an antigen but exhibit various effector functions, such as participation of the antibody in antibody-dependent cellular toxicity.

[0153] As used herein, the terms "CDR," "HVR," or "HV" generally refer to regions of an antibody variable domain that are hypervariable in sequence and / or form structurally defined loops. Antibodies typically contain six CDRs: three in the VH (HCDR1, HCDR2, and HCDR3) and three in the VL (LCDR1, LCDR2, and LCDR3). An ISVD of the present disclosure may consist of only three CDRs (e.g., in the VH, HCDR1, HCDR2, and HCDR3). In natural antibodies, HCDR3 and LCDR3 are the most diverse of the six CDRs, and HCDR3 in particular is believed to play a unique role in conferring fine specificity to antibodies. See, e.g., Xu et al., Immunity 13:37-45 (2000); Johnson and Wu, in Methods in Molecular Biology 248:1-25 (Lo, ed., Human Press, Totowa, NI, 2003). Indeed, natural camelid antibodies consisting only of heavy chains are functional and stable in the absence of light chains (see, e.g., Hamers-Casterman et al., Nature 363:446-448 (1993); Sheriff et al., Nature Struct. Biol. 3:733-736 (1996)).

[0154] Many CDR delineations are in use and are encompassed herein. Kabat complementarity-determining regions (CDRs) are based on sequence variability and are the most commonly used (see Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed., Public Health Service, National Institutes of Health, Bethesda, Md., with EU index numbering. (1991)). Chothia refers instead to the location of the structural loops (Chothia and Lesk, J. Mol. Biol. 196:901-917 (1987)). AbM CDRs represent a compromise between Kabat HVRs and Chothia structural loops and are used by Oxford Molecular's AbM antibody modeling software.

[0155] The "contact" CDRs are based on an analysis of the available complex crystal structures. Residues from each of these CDRs are shown in Table 1. [Table 1]

[0156] CDRs may include "extended CDRs" as follows: 24-36 or 24-34 (LCDR1), 46-56 or 50-56 (LCDR2) and 89-97 or 89-96 (LCDR3) for VL, and 26-35 (HCDR1), 50-65 or 49-65 (HCDR2) and 93-102, 94-102 or 95-102 (HCDR3) for VH. The variable domain residues are numbered according to Kabat et al., supra, for each of these definitions.

[0157] The phrases "variable domain residue-numbering as in Kabat" or "amino acid-position numbering as in Kabat" and variations thereof generally refer to the numbering system used for the heavy or light chain variable domains of a dimer / polypeptide chain compilation in Kabat et al., supra. The Kabat numbering of residues can be determined for a given polypeptide by aligning the regions of sequence homology of the polypeptide with the "standard" Kabat numbered sequence.

[0158] "Framework" or "FR" residues are variable domain residues other than CDR residues as defined herein. A "human consensus framework" or "acceptor human framework" is a framework representing the most commonly occurring amino acid residues in a selection of human immunoglobulin VL or VH framework sequences. Generally, the selection of human immunoglobulin VL or VH sequences is from a subgroup of variable domain sequences. Generally, the subgroup of sequences is a subgroup in K. Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed., or the EU index numbering in Public Health Service, National Institutes of Health, Bethesda, Md. (1991). By way of example, for VL, the subgroup can be subgroup kappa I, kappa II, kappa III, or kappa IV as in K. Kabat et al., supra. Additionally, for VH, the subgroup can be subgroup I, subgroup II, or subgroup III as in K. Kabat et al., supra. Alternatively, a human consensus framework can be derived from the above, such as when human framework residues are selected based on their homology to the donor framework by aligning the donor framework sequence with a collection of different human framework sequences. A recipient human framework "derived" from a human immunoglobulin framework or human consensus framework can contain the same amino acid sequence or can contain pre-existing amino acid sequence changes. In some embodiments, the number of pre-existing amino acid changes is 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, 6 or fewer, 5 or fewer, 4 or fewer, 3 or fewer, or 2 or fewer.

[0159] The term "substantially unresponsive" is commonly used to describe one or more conventional therapies (e.g., tumor treatments), such as chemotherapy, radiation therapy, surgery, hormonal therapy, and / or biological therapy / immunotherapy, particularly standard treatment regimens for treating patients with certain tumors, meaning that the treatment methods are not sufficient to cure the patient in clinical practice; e.g., the patient may still be sensitive to the treatment, and therefore these patients require further effective treatment. The term is also used to describe situations that respond to treatment, such as side effects, recurrence, or resistance. In some embodiments, "substantially unresponsive" means that the patient is refractory, intolerant, or refusing standard therapy for treating the tumor, including that the patient may show objective evidence of disease progression despite treatment with an immune checkpoint inhibitor.

[0160] In this disclosure, an amino acid sequence or nucleotide sequence set forth in a particular SEQ ID NO also includes homologs or variants thereof having substantially the same function / property, e.g., sequences having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or more sequence identity; and / or variants having one or more (e.g., a small number, such as 1-10, 1-9, 1-8, 1-7, 1-6, 1-5, 1-4, 1-3, 1-2) amino acid or nucleotide additions, deletions, or substitutions.

[0161] dimer

[0162] In one aspect, the present disclosure provides use of a dimer in the preparation of a medicament for treating a tumor in a subject in need thereof, said dimer being formed by two polypeptide chains, each of said two polypeptide chains comprising an antibody Fc subunit, said dimer comprising two or more immunoglobulin single variable domains (ISVDs), at least one of said ISVDs being specific for PD-L1 and at least one of said ISVDs being specific for CTLA4.

[0163] In another aspect, the present disclosure provides a method of treating a tumor in a subject in need thereof, comprising administering to said subject an effective amount of a dimer.

[0164] In some embodiments, a dimer can be formed by two polypeptide chains, each of which contains an antibody Fc subunit. For example, a dimer can be composed of two poly-F peptide chains, each of which contains an antibody Fc subunit, and the antibody Fc subunit of one polypeptide chain can associate with the antibody Fc subunit of the other polypeptide chain to form a dimer. In one example, the two polypeptide chains of the dimer are not fused to each other (e.g., via a peptide linker or by a peptide bond) to form a single polypeptide chain.

[0165] A dimer can contain two or more immunoglobulin single variable domains (ISVDs). For example, one polypeptide chain of the dimer can contain two or more ISVDs, while the other polypeptide chain of the dimer does not contain any ISVDs. In another example, each of the two polypeptide chains can contain one or more ISVDs. In yet another example, each of the two polypeptide chains can be composed of two or more ISVDs.

[0166] At least one of the ISVDs may be specific for PD-L1, and at least one of the ISVDs may be specific for CTLA4. For example, one polypeptide chain of a dimer may include one or more ISVDs specific for PD-L1 and one or more ISVDs specific for CTLA4, while the other polypeptide chain of the dimer does not include any ISVDs. In another example, one polypeptide chain of a dimer may include one or more ISVDs specific for PD-L1, while the other polypeptide chain of the dimer may include one or more ISVDs specific for CTLA4. In another example, one polypeptide chain of a dimer may include one or more ISVDs specific for PD-L1 and one or more ISVDs specific for CTLA4, while the other polypeptide chain of the dimer may include one or more ISVDs specific for PD-L1 and / or one or more ISVDs specific for CTLA4.

[0167] The one or more ISVDs specific for PD-L1 may be the same or different. The one or more ISVDs specific for CTLA4 may be the same or different.

[0168] In some cases, the PD-L1-specific ISVD does not comprise any antibody light chain CDRs. In some cases, the PD-L1-specific ISVD does not comprise any antibody light chain variable regions. In some cases, the PD-L1-specific ISVD does not comprise any antibody light chain or fragment thereof. In some cases, the PD-L1-specific ISVD comprises at least a heavy chain CDR3. In some cases, the PD-L1-specific ISVD comprises a heavy chain CDR1. In some cases, the PD-L1-specific ISVD comprises a heavy chain CDR2. In some cases, the PD-L1-specific ISVD comprises a heavy chain variable region. In some cases, the PD-L1-specific ISVD is an anti-PD-L1 VHH. The PD-L1-specific ISVD may be humanized.

[0169] In some cases, the CTLA4-specific ISVD does not comprise any antibody light chain CDRs. In some cases, the CTLA4-specific ISVD does not comprise any antibody light chain variable region. In some cases, the CTLA4-specific ISVD does not comprise any antibody light chain or fragment thereof. In some cases, the CTLA4-specific ISVD comprises at least a heavy chain CDR3. In some cases, the CTLA4-specific ISVD comprises a heavy chain CDR1. In some cases, the CTLA4-specific ISVD comprises a heavy chain CDR2. In some cases, the CTLA4-specific ISVD comprises a heavy chain variable region. In some cases, the CTLA4-specific ISVD is an anti-CTLA4 VHH. The CTLA4-specific ISVD may be humanized.

[0170] In some cases, at least one of the two polypeptide chains may comprise both an ISVD specific for PD-L1 and an ISVD specific for CTLA4. For example, one of the two polypeptide chains may comprise one or more ISVDs specific for PD-L1 and one or more ISVDs specific for CTLA4. In another example, each of the two polypeptide chains may comprise one or more ISVDs specific for PD-L1 and one or more ISVDs specific for CTLA4.

[0171] For one or both of the two polypeptide chains, the PD-L1-specific ISVD may be fused, optionally via a linker, to a CTLA4-specific ISVD. For example, there may be one or more PD-L1-specific ISVDs and one or more CTLA4-specific ISVDs in one or both of the two polypeptide chains. When two or more PD-L1-specific ISVDs are present in a single polypeptide chain, they may be fused to each other (e.g., directly or via a peptide linker), and one or more of them may be further fused to one or more CTLA4-specific ISVDs. When two or more CTLA4-specific ISVDs are present in a single polypeptide chain, they may be fused to each other (e.g., directly or via a peptide linker), and one or more of them may be further fused to one or more PD-L1-specific ISVDs. One or more linkers (e.g., peptide linkers) can be present between any two ISVDs, for example, between two ISVDs specific for PD-L1, between two ISVDs specific for CTLA4, or between one ISVD specific for PD-L1 and one ISVD specific for CTLA4.

[0172] For one or both of the two polypeptide chains, the PD-L1-specific ISVD may be fused to the CTLA4-specific ISVD, optionally via a linker; and the CTLA4-specific ISVD may in turn be fused to the antibody Fc subunit, optionally via a linker. For example, in a single polypeptide chain, the PD-L1-specific ISVD may be fused directly (e.g., in-frame) or via a linker to the CTLA4-specific ISVD, and the CTLA4-specific ISVD may be fused directly (e.g., in-frame) or via a linker to the antibody Fc subunit. When two or more PD-L1-specific ISVDs and / or one or more CTLA4-specific ISVDs are present in a single polypeptide chain, the PD-L1-specific ISVDs and CTLA4-specific ISVDs may be fused to each other directly or via a linker in any order, and at least one ISVD specific for CTLA4 may be fused directly (e.g., in-frame) or via a linker to the antibody Fc subunit. For example, for one or both of the two polypeptide chains, the C-terminus of the PD-L1-specific ISVD may be fused to the N-terminus of the CTLA4-specific ISVD, optionally via a linker; and the C-terminus of the CTLA4-specific ISVD may be fused to the N-terminus of an antibody Fc subunit, optionally via a linker. For example, in a single polypeptide chain, the C-terminus of one of the PD-L1-specific ISVDs may be fused to the N-terminus of one of the CTLA4-specific ISVDs directly (e.g., in-frame) or via a linker, and the C-terminus of one of the CTLA4-specific ISVDs may be fused to the N-terminus of the antibody Fc subunit directly (e.g., in-frame) or via a linker.In one example, when one or more ISVDs specific for PD-L1 and / or one or more ISVDs specific for CTLA4 are present in a single polypeptide chain, the PD-L1-specific ISVDs and CTLA4-specific ISVDs may be fused to each other in any order, either directly or via a linker, but the C-terminus of at least one ISVD specific for PD-L1 may be fused, directly (e.g., in frame) or via a linker, to the N-terminus of at least one ISVD specific for CTLA4, and the C-terminus of at least one ISVD specific for CTLA4 may be fused, directly (e.g., in frame) or via a linker, to the N-terminus of an antibody Fc subunit.

[0173] For one or both of the two polypeptide chains, the CTLA4-specific ISVD may be fused, optionally via a linker, to the PD-L1-specific ISVD; and the PD-L1-specific ISVD may then be fused, optionally via a linker, to the antibody Fc subunit. For example, in a single polypeptide chain, the CTLA4-specific ISVD may be fused directly (e.g., in-frame) or via a linker to the PD-L1-specific ISVD, and the PD-L1-specific ISVD may be fused directly (e.g., in-frame) or via a linker to the antibody Fc subunit. When two or more PD-L1-specific ISVDs and / or two or more CTLA4-specific ISVDs are present in a single polypeptide chain, the PD-L1-specific ISVDs and CTLA4-specific ISVDs may be fused to each other directly or via linkers in any order, and at least one PD-L1-specific ISVD may be fused directly (e.g., in-frame) or via a linker to an antibody Fc subunit. For example, for one or both of the two polypeptide chains, the C-terminus of the CTLA4-specific ISVD may be fused to the N-terminus of the PD-L1-specific ISVD, optionally via a linker; and the C-terminus of the PD-L1-specific ISVD may be fused to the N-terminus of the antibody Fc subunit, optionally via a linker. For example, in a single polypeptide chain, the C-terminus of one of the CTLA4-specific ISVDs may be fused directly (e.g., in frame) or via a linker to the N-terminus of one of the PD-L1-specific ISVDs, and the C-terminus of one of the PD-L1-specific ISVDs may be fused directly (e.g., in frame) or via a linker to the N-terminus of an antibody Fc subunit.

[0174] In one example, when one or more ISVDs specific for PD-L1 and / or one or more ISVDs specific for CTLA4 are present in a single polypeptide chain, the PD-L1-specific ISVDs and CTLA4-specific ISVDs may be fused to each other in any order, either directly or via a linker, but the C-terminus of at least one ISVD specific for CTLA4 may be fused directly (e.g., in frame) or via a linker to the N-terminus of at least one ISVD specific for PD-L1, and the C-terminus of at least one ISVD specific for PD-L1 may be fused directly (e.g., in frame) or via a linker to the N-terminus of an antibody Fc subunit.

[0175] A linker (e.g., a peptide linker) used in the present application (e.g., as constituted by a dimer of the present application) may be a synthetic amino acid sequence that links or connects two polypeptide sequences, for example, via a peptide bond. For example, a peptide linker can contain 1 to 10 amino acids (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more amino acids), 1 to 15 amino acids (e.g., 1 to 10, 11, 12, 13, 14, or 15 amino acids), 1 to 20 amino acids (e.g., 1 to 15, 16, 17, 18, 19, or 20 amino acids), or 1 to 30 or more amino acids (e.g., 1 to 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 or more amino acids). For example, a peptide linker can contain the amino acid sequence set forth in any one of SEQ ID NOs: 33-34. For example, a peptide linker can contain the amino acid sequence set forth in SEQ ID NO: 33.

[0176] The antibody Fc subunit may be derived from an IgG Fc subunit. For example, the IgG may be selected from the group consisting of IgG1, IgG2, IgG3, and IgG4. In some embodiments, the IgG is a human IgG1, and the IgG Fc subunit is a human IgG1 Fc subunit. In some embodiments, the Fc subunit comprises an amino acid sequence having at least 80% identity (e.g., at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 100%) to the amino acid sequence set forth in any one of SEQ ID NOs: 35, 38, and 39. For example, the Fc subunit may comprise an amino acid sequence having one or more (e.g., 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10 or more) amino acid deletions, insertions, and / or substitutions in the amino acid sequence set forth in any of SEQ ID NOs: 35, 38, and 39. For example, the Fc subunit may comprise an amino acid sequence having one or more (e.g., 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10 or more) amino acid deletions, insertions, and / or substitutions in the amino acid sequence set forth in any of SEQ ID NOs: 38 and 39.

[0177] In some embodiments, the Fc subunit may be a variant of an IgG Fc subunit (e.g., a variant of a human IgG1 Fc subunit). For example, the variant may contain one or more amino acid mutations that enhance or decrease ADCC or CDC activity. As another example, the variant may contain one or more amino acid mutations that affect FcRn-binding activity and / or the half-life of a molecule comprising the variant. As yet another example, the variant may contain one or more amino acid mutations that affect the interaction (e.g., association) between two or more Fc subunits (or Fc monomers) and / or increase or decrease the efficiency of Fc heterodimer formation; for example, the variant may contain one or more amino acid substitutions as described in CN 102558355 A, CN 103388013 A, CN 105820251 A, or CN 106883297 A, each of which is incorporated herein by reference.

[0178] The PD-L1-specific ISVD may specifically bind to human PD-L1. For example, the PD-L1-specific ISVD may specifically bind to an epitope within the extracellular domain of human PD-L1. Such epitopes are known in the art, for example, as shown by Gang Hao et al., J. Mol. Recognit. 2015; 28: 269-276, Zhang et al., Oncotarget. 2017 Oct; 08 (52): 90215-90224, and Zhang et al., Cell Discov. 2017 Mar 7; 3:17004.

[0179] For example, a PD-L1-specific ISVD may bind to the N-terminal IgV domain of human PD-L1. The N-terminal IgV domain of human PD-L1 (including the signal peptide) may comprise the amino acid sequence set forth in SEQ ID NO: 64. In the present disclosure, a PD-L1-specific ISVD may bind to residues 154, Y56, E58, Q66, and / or R113 of the human PD-L1 N-terminal IgV domain. In a specific embodiment, a PD-L1-specific ISVD may bind to residues 154, Y56, E58, Q66, and / or R113 of the human PD-L1 N-terminal IgV domain (e.g., amino acid residues 154, Y56, E58, Q66, and / or R113 of SEQ ID NO: 64). The PD-L1-specific ISVD may further bind to residues D61, N63, V68, M115, S117, Y123 and / or R125 of the human PD-L1 N-terminal IgV domain (e.g., amino acid residues D61, N63, V68, M115, S117, Y123 and / or R125 of SEQ ID NO: 64). In some cases, the PD-L1-specific ISVD may bind to amino acid residues 154, Y56, E58, Q66, R113, D61, N63, V68, M115, S117, Y123, and / or R125 of the human PD-L1 N-terminal IgV domain (e.g., amino acid residues 154, Y56, E58, Q66, R113, D61, N63, V68, M115, S117, Y123, and / or R125 of SEQ ID NO: 64). In some cases, the PD-L1-specific ISVD may bind to a conformational epitope in the human PD-L1 N-terminal IgV domain, and the conformational epitope may include residues 154, Y56, E58, Q66, and / or R113 in the human PD-L1 N-terminal IgV domain (e.g., amino acid residues 154, Y56, E58, Q66, and / or R113 of SEQ ID NO: 64).In some cases, the PD-L1-specific ISVD may bind to a conformational epitope in the human PD-L1 N-terminal IgV domain, and the conformational epitope may include amino acid residues 154, Y56, E58, Q66, R113, D61, N63, V68, M115, S117, Y123, and / or R125 of the human PD-L1 N-terminal IgV domain (e.g., amino acid residues 154, Y56, E58, Q66, R113, D61, N63, V68, M115, S117, Y123, and / or R125 of SEQ ID NO: 64).

[0180] The PD-L1-specific ISVDs of the present disclosure (e.g., PD-L1 ISVD-9 and its humanized variants) bind to the N-terminal IgV domain of human PD-L1. Taking PD-L1 ISVD-9 as an example, residue Phe101 (SEQ ID NO: 6) of PD-L1 ISVD-9 interacts with Tyr56 in the human PD-L1 N-terminal IgV domain. When Tyr56 in the human PD-L1 N-terminal IgV domain was replaced with Ala, the binding affinity between PD-L1 ISVD-9 and PD-L1 decreased by more than 200-fold. When Ile54 in the human PD-L1 N-terminal IgV domain was replaced with Ala, the binding affinity between PD-L1 ISVD-9 and PD-L1 decreased by approximately 40-fold. Residue Asp 99 (SEQ ID NO: 6) of PD-L1 ISVD-9 interacts with Argl 3 of the human PD-L1 N-terminal IgV domain, and replacing Argl 3 of the human PD-L1 N-terminal IgV domain with Ala reduced the binding affinity of PD-L1 ISVD-9 to PD-L1 by approximately 90-fold. Residue Seri 00 (SEQ ID NO: 6) of PD-L1 ISVD-9 interacts with Glu 58 of the human PD-L1 N-terminal IgV domain, and replacing Glu 58 of the human PD-L1 N-terminal IgV domain with Ala reduced the binding affinity of PD-L1 ISVD-9 to PD-L1 by approximately 25-fold. Residue Thrl05 (SEQ ID NO: 6) of PD-L1 ISVD-9 interacts with Gln66 in the human PD-L1 N-terminal IgV domain, and substituting Gln66 with Ala reduced the binding affinity of PD-L1 ISVD-9 to PD-L1 by approximately 82-fold. Furthermore, residues D61, N63, V68, M115, S117, Y123, and R125 in the human PD-L1 N-terminal IgV domain may be involved in the interaction between PD-L1 ISVD-9 and human PD-L1, and substituting these residues with Ala reduced the binding affinity by approximately 2-10-fold. These results are summarized in Table 2 below. [Table 2]

[0181] The PD-L1-specific ISVD can block the binding of PD-L1 to PD1. In some cases, the PD-L1-specific ISVD can block the binding of PD-L1 to CD80.

[0182] The PD-L1 specific ISVD can cross-compete with a control anti-PD-L1 antibody for binding to PD-L1.

[0183] The reference anti-PD-L1 antibody may comprise a heavy chain CDR3. The heavy chain CDR3 is DSFX1X2PTCX3X4X 5X6 Optionally, the reference anti-PD-L1 antibody may comprise a heavy chain CDR3 consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 5 and 9. The reference anti-PD-L1 antibody may also comprise a heavy chain CDR1. The heavy chain CDR1 may comprise the amino acid sequence set forth in GX1X2X3X4X5RCMA (SEQ ID NO: 2), where X1 may be K or N; X2 may be M or I; X3 may be S or I; X4 may be S or R; and X5 may be R or V. For example, the reference anti-PD-L1 antibody may comprise a heavy chain CDR1 consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 3 and 7. Optionally, the reference anti-PD-L1 antibody may comprise a heavy chain CDR2. The heavy chain CDR2 may comprise the amino acid sequence set forth in any one of SEQ ID NOs: 4, 8, and 11. Optionally, the reference anti-PD-L1 antibody is an ISVD specific for PD-L1, such as an anti-PD-L1 VHH. The reference anti-PD-L1 antibody may comprise a heavy chain variable domain. The reference anti-PD-L1 antibody may comprise a heavy chain variable domain consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 6, 10, 12, 13, 14, and 15. For example, the heavy chain variable domain may comprise the amino acid sequence set forth in SEQ ID NO: 6.

[0184] In the present disclosure, a PD-L1-specific ISVD (e.g., as included in a dimer of the present disclosure) can comprise a heavy chain CDR3. The heavy chain CDR3 is DSFX1X2PTCX3X4X 5X6 X5 may be V or P; and X6 may be T or A. For example, an ISVD specific for PD-L1 may comprise a heavy chain CDR3 consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 5 and 9.

[0185] For example, a PD-L1-specific ISVD may comprise a heavy chain CDR3 consisting of an amino acid sequence that is at least 80% identical (e.g., at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 100%) to the amino acid sequence set forth in any one of SEQ ID NOs: 5 and 9. Optionally, the heavy chain CDR3 may comprise an amino acid sequence having one or more (e.g., 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, or more) amino acid deletions, insertions, and / or substitutions in the sequence set forth in any one of SEQ ID NOs: 5 and 9.

[0186] In the present disclosure, a PD-L1-specific ISVD (e.g., as included in a dimer of the present disclosure) may also comprise a heavy chain CDR1. The heavy chain CDR1 may comprise the amino acid sequence set forth in GX1X2X3X4X5RCMA (SEQ ID NO: 2), where X1 may be K or N; X2X3 may be M or I; X4 may be S or R; and X5 may be R or V. For example, an ISVD specific for PD-L1 may comprise a heavy chain CDR1 consisting of the amino acid sequence set forth in either SEQ ID NO: 3 or 7.

[0187] For example, a PD-L1-specific ISVD may comprise a heavy chain CDR1 consisting of an amino acid sequence that is at least 80% identical (e.g., at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 100%) to the amino acid sequence set forth in any one of SEQ ID NOs: 3 and 7. Optionally, the heavy chain CDR1 may comprise an amino acid sequence having one or more (e.g., 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, or more) amino acid deletions, insertions, and / or substitutions in the sequence set forth in any one of SEQ ID NOs: 3 and 7.

[0188] In the present disclosure, a PD-L1-specific ISVD (e.g., as included in a dimer of the present disclosure) may further comprise a heavy chain CDR2. The heavy chain CDR2 may comprise any suitable amino acid sequence. In some cases, the PD-L1-specific ISVD may comprise a heavy chain CDR2 consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 4, 8, and 11.

[0189] For example, a PD-L1-specific ISVD may comprise a heavy chain CDR2 consisting of an amino acid sequence that is at least 80% identical (e.g., at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 100%) to the amino acid sequence set forth in any one of SEQ ID NOs: 4, 8, and 11. Optionally, the heavy chain CDR2 may comprise an amino acid sequence having one or more (e.g., 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, or more) amino acid deletions, insertions, and / or substitutions in the sequence set forth in any one of SEQ ID NOs: 4, 8, and 11.

[0190] For example, a PD-L1-specific ISVD may comprise a CDR3 comprising the amino acid sequence set forth in SEQ ID NO:5, a CDR2 comprising the amino acid sequence set forth in SEQ ID NO:4, and a CDR1 consisting of the amino acid sequence set forth in SEQ ID NO:3.

[0191] In the present disclosure, the PD-L1-specific ISVD (included in the dimers of the present disclosure) may comprise a heavy chain variable domain. The PD-L1-specific ISVD may comprise a heavy chain variable domain consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 6, 10, 12, 13, 14, and 15. For example, the heavy chain variable domain may comprise the amino acid sequence set forth in SEQ ID NO: 6.

[0192] For example, a PD-L1-specific ISVD can comprise a heavy chain variable domain consisting of an amino acid sequence that is at least 80% identical (e.g., at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 100%) to the amino acid sequence set forth in any one of SEQ ID NOs: 6, 10, 12, 13, 14, and 15. In some cases, the PD-L1-specific ISVD may comprise a heavy chain variable domain consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 6, 10, 12, 13, 14, and 15, with one or more (e.g., 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10 or more) amino acid deletions, insertions, and / or substitutions.

[0193] In the present disclosure, a PD-L1-specific ISVD may comprise the amino acid sequence set forth in any one of SEQ ID NOs: 6, 10, 12, 13, 14, and 15. For example, a PD-L1-specific ISVD (included in a dimer of the present disclosure) may comprise the amino acid sequence set forth in SEQ ID NO: 6. For example, a PD-L1-specific ISVD may comprise an amino acid sequence that is at least 80% identical (e.g., at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 100%) to the amino acid sequence set forth in any one of SEQ ID NOs: 6, 10, 12, 13, 14, and 15. In some cases, the PD-L1-specific ISVD may comprise an amino acid sequence having one or more (e.g., 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, or more) amino acid deletions, insertions, and / or substitutions in any one of SEQ ID NOs: 6, 10, 12, 13, 14, and 15.

[0194] In some cases, the PD-L1-specific ISVD comprises or consists of a heavy chain variable domain (VH or VHH).

[0195] For example, the PD-L1-specific ISVD can be selected from PD-L1 ISVD-9, PD-L1 ISVD-6, PD-L1 ISVD-m 3, PD-L1 ISVD-4, PD-L1 ISVD-11, and PD-L1 ISVD- 13. As another example, the PD-L1-specific ISVD can be selected from PD-L1 ISVD-9.

[0196] The CTLA4-specific ISVD can specifically bind to human CTLA4. For example, the CTLA4-specific ISVD can specifically bind to an epitope in the extracellular domain of human CTLA4, and such epitopes can include those described in CN107400166A and those described in Udupi A. Ramagopal, et. al., PNAS 2017 May, 114 (21), etc.

[0197] The CTLA4-specific ISVD can block the binding of CTLA4 to CD 80. In some cases, the CTLA4-specific ISVD can block the binding of CTLA4 to CD 86. In some cases, the CTLA4-specific ISVD can be humanized.

[0198] An ISVD specific for CTLA4 can cross-compete with a reference anti-CTLA4 antibody for binding to CTLA4.

[0199] The reference anti-CTLA4 antibody may comprise a heavy chain CDR3. The heavy chain CDR3 may comprise the amino acid sequence set forth in SEQ ID NO: 19. The reference anti-CTLA4 antibody may also comprise a heavy chain CDR1. The heavy chain CDR1 may comprise the amino acid sequence set forth in SEQ ID NO: 17. Optionally, the reference anti-CTLA4 antibody may comprise a heavy chain CDR2. The heavy chain CDR2 may comprise the amino acid sequence set forth in AIX1X2GGGSTYYADSVKG (SEQ ID NO: 16), where X1 may be Y or S; and X2 may be I or L. For example, the heavy chain CDR2 may comprise the amino acid sequence set forth in any one of SEQ ID NOs: 18, 21, and 23. Optionally, the reference anti-CTLA4 antibody is an ISVD specific for CTLA4, such as an anti-CTLA4 VHH. The reference anti-CTLA4 antibody may comprise a heavy chain variable domain. The reference anti-CTLA4 antibody may comprise a heavy chain variable domain consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 20, 22, and 24-32. For example, the heavy chain variable domain can comprise the amino acid sequence set forth in SEQ ID NO:20.

[0200] In the present disclosure, a CTLA4-specific ISVD (e.g., as included in a dimer of the present disclosure) can comprise a heavy chain CDR3. The heavy chain CDR3 can comprise the amino acid sequence set forth in SEQ ID NO:19.

[0201] In some cases, the CTLA4-specific ISVD may comprise a heavy chain CDR3 consisting of an amino acid sequence having at least 80% (e.g., at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 100%) identity to the amino acid sequence set forth in SEQ ID NO: 19. In some cases, the heavy chain CDR3 may comprise an amino acid sequence having one or more (e.g., 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, or more) amino acid deletions, insertions, and / or substitutions in the sequence set forth in SEQ ID NO: 19.

[0202] In the present disclosure, an ISVD specific for CTLA4 (e.g., as included in a dimer of the present disclosure) can comprise a heavy chain CDR1. The heavy chain CDR1 can comprise the amino acid sequence set forth in SEQ ID NO:17.

[0203] In some cases, the CTLA4-specific ISVD may comprise a heavy chain CDR1 consisting of an amino acid sequence having at least 80% (e.g., at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 100%) identity to the amino acid sequence set forth in SEQ ID NO: 17. In some cases, the heavy chain CDR1 may comprise an amino acid sequence having one or more (e.g., 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, or more) amino acid deletions, insertions, and / or substitutions in the sequence set forth in SEQ ID NO: 17.

[0204] In the present disclosure, a CTLA4-specific ISVD (e.g., as included in a dimer of the present disclosure) can further comprise a heavy chain CDR2. The heavy chain CDR2 can comprise the amino acid sequence set forth in AIX1X2GGGSTYYADSVKG (SEQ ID NO: 16), where X1 can be Y or S; and X2 can be I or L. In some cases, a CTLA4-specific ISVD can comprise a heavy chain CDR2 consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 18, 21, and 23.

[0205] For example, a CTLA4-specific ISVD may comprise a heavy chain CDR2 consisting of an amino acid sequence having at least 80% identity (e.g., at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 100%) to the amino acid sequence set forth in any one of SEQ ID NOs: 18, 21, and 23. In some cases, the heavy chain CDR2 may comprise an amino acid sequence having one or more (e.g., 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, or more) amino acid deletions, insertions, and / or substitutions in the sequence set forth in any one of SEQ ID NOs: 18, 21, and 23.

[0206] For example, a PD-L1-specific ISVD may comprise a CDR3 comprising the amino acid sequence set forth in SEQ ID NO: 19, a CDR2 comprising the amino acid sequence set forth in SEQ ID NO: 18, and a CDR1 consisting of the amino acid sequence set forth in SEQ ID NO: 17.

[0207] In the present disclosure, a CTLA4-specific ISVD (contained in a dimer of the present disclosure) may comprise a heavy chain variable domain. The CTLA4-specific ISVD may comprise a heavy chain variable domain consisting of the amino acid sequence set forth in any one of SEQ ID NOs: 20, 22, and 24 to 32. For example, the heavy chain variable domain may comprise the amino acid sequence set forth in SEQ ID NO: 20.

[0208] For example, an ISVD specific to CTLA4 may comprise a heavy chain variable domain consisting of an amino acid sequence having at least 80% identity (e.g., at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 100%) to the amino acid sequence set forth in any one of SEQ ID NOs: 20, 22, and 24 to 32. In some cases, the CTLA4-specific ISVD may comprise a heavy chain variable domain consisting of an amino acid sequence having one or more (e.g., 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, or more) amino acid deletions, insertions, and / or substitutions in any one of SEQ ID NOs: 20, 22, and 24-32.

[0209] In the present disclosure, a CTLA4-specific ISVD may comprise the amino acid sequence set forth in any one of SEQ ID NOs: 20, 22, and 24 to 32. For example, a CTLA4-specific ISVD (included in a dimer of the present disclosure) may comprise the amino acid sequence set forth in SEQ ID NO: 20.

[0210] For example, a CTLA4-specific ISVD can comprise an amino acid sequence having at least 80% identity (e.g., at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 100%) to the amino acid sequence set forth in any one of SEQ ID NOs: 20, 22, and 24-32. In some cases, a CTLA4-specific ISVD can comprise an amino acid sequence having one or more (e.g., 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, or more) amino acid deletions, insertions, and / or substitutions in the sequence set forth in any one of SEQ ID NOs: 20, 22, and 24-32.

[0211] In some cases, the CTLA4-specific ISVD comprises or consists of a heavy chain variable domain (VH or VHH).

[0212] For example, the CTLA4-specific ISVD can be selected from CTLA4 ISVD-34, CTLA4 ISVD-C1, CTLA4 ISVD-13, CTLA4 ISVD-26, CTLA4 ISVD-27, CTLA4 ISVD-28, CTLA4 ISVD-29, CTLA4 ISVD-30, CTLA4 ISVD-31, CTLA4 ISVD-32, and CTLA4 ISVD-33.

[0213] For example, a dimer of the present application can comprise or consist of two polypeptide chains. The amino acid sequences of the two polypeptide chains can be identical or different. In some cases, a dimer of the present disclosure can be a homodimer.

[0214] In the present disclosure, one or both of the two polypeptide chains of the dimer may comprise the amino acid sequence set forth in any one of claims 40 to 43, 46, 48, and 50. For example, one or both of the two polypeptide chains of the dimer may comprise the amino acid sequence set forth in SEQ ID NO:40.

[0215] In specific examples, one or both of the two polypeptide chains of the dimer may comprise an amino acid sequence having at least 80% identity (e.g., at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 100%) to the amino acid sequence set forth in any one of SEQ ID NOs: 40-43, 46, 48, and 50. In some cases, one or both of the two polypeptide chains of the dimer may comprise an amino acid sequence having one or more (e.g., 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10 or more) amino acid deletions, insertions and / or substitutions in the sequence set forth in any one of SEQ ID NOs: 40-43, 46, 48 and 50.

[0216] As one example, an ISVD specific for PD-L1 may be fused (directly or indirectly, e.g., via a linker such as a peptide linker) to the N-terminal amino acid of an ISVD specific for CTLA4 to form a bispecific binding moiety. One such bispecific binding moiety may then be fused (directly or indirectly, e.g., via a linker such as a peptide linker) to the N-terminal amino acid of one Fc subunit of the present disclosure to provide one polypeptide chain of a dimer. Another such bispecific binding moiety may then be fused (directly or indirectly, e.g., via a linker such as a peptide linker) to the N-terminal amino acid of another Fc subunit of the present disclosure to provide the other polypeptide chain of the dimer. The two Fc subunits of the two polypeptide chains may be linked to each other (e.g., via non-covalent interactions and / or disulfide bonds or other covalent bonds, optionally where such covalent bonds are not peptide bonds) to form a dimer. The two biospecific binding moieties may be the same or different. The two Fc subunits may be the same or different.

[0217] In some embodiments, the dimer is a proteinaceous homodimer comprising two identical polypeptide chains, each comprising one of the bispecific binding moieties fused to one of the Fc subunits, and the two Fc subunits binding to one another to form the proteinaceous homodimer. The two Fc subunits may be bound to one another via non-covalent interactions and / or disulfide bonds or other covalent bonds, and optionally, such covalent bonds are not peptide bonds.

[0218] Figures 1A-1B provide examples of dimers of the present disclosure, where 1 shows an ISVD specific for PD-L1, 2 shows an ISVD specific for CTLA4, 3 shows an Fc domain comprising an Fc subunit, and 4 shows a bispecific binding moiety.

[0219] The dimers of the present disclosure can compete with CD80 and / or CD86 for binding to CTLA4. For example, competition can be examined in an in vitro experiment using a CTLA4-expressing cell line, such as a CTLA4-expressing HEK293 cell line. As another example, competition can be tested in an ELISA assay, such as a competitive ELISA assay.

[0220] Dimers of the present disclosure can compete with PD1 and / or CD80 for binding to PD-L1. For example, competition can be examined in an in vitro experiment using a PD-L1-expressing cell line, such as the PD-L1-expressing A375 cell line. As another example, competition can be tested in an ELISA assay, such as a competitive ELISA assay.

[0221] The dimers of the present disclosure can block the binding of PD-L1 to PD-1. In some cases, the dimers of the present disclosure can block the binding of PD-L1 to CD80. In some cases, the dimers of the present disclosure can block the binding of CTLA4 to CD80. In some cases, the dimers of the present disclosure can block the binding of CTLA4 to CD86.

[0222] The dimer of the present disclosure is about 1x10 -6 M or less, for example, about lx10 -7 M or less, about lx10 -8 M or less, about 0.5x10 -8 M or less, about lx10 -9 M or less, about lx10 -10 K less than or equal to M D can bind to CTLA4.

[0223] The dimer of the present disclosure is about 1x10 -6 M or less, for example, about lx10 -7 M or less, about lx10 -8 M or less, about 0.5x10 -8 M or less, about lx10 -9 M or less, about lx10 -10 It may bind to PD-L1 at or below M.

[0224] The dimers of the present disclosure can stimulate the secretion of immunomodulatory substances (eg, IL-2) by immune cells (eg, PBMC cells).

[0225] For example, a dimer of the present disclosure can be selected from aPDL1.9-aCTLA4.34-Fc, aPDL1.9-L-aCTLA4.34-Fc, aCTLA4.34-aPDL1.9-Fc, aCTLA4.34-L-aPDL1.9-Fc, aPDL1.6-aCTLA4.34-Fc, aPDL1.m3-aCTLA4.34-Fc, and aPDL1.9-aCTLA4.13-Fc.

[0226] For example, a dimer of the present disclosure may comprise a CTLA4-specific ISVD and a PDL1-specific ISVD. The PD-L1-specific ISVD may comprise a CDR3 comprising the amino acid sequence set forth in SEQ ID NO:5, a CDR2 comprising the amino acid sequence set forth in SEQ ID NO:4, and a CDR1 comprising the amino acid sequence set forth in SEQ ID NO:3. Alternatively, the CTLA4-specific ISVD may comprise a CDR3 comprising the amino acid sequence set forth in SEQ ID NO:19, a CDR2 comprising the amino acid sequence set forth in SEQ ID NO:18, and a CDR1 comprising the amino acid sequence set forth in SEQ ID NO:17. Alternatively, a dimer of the present disclosure may comprise a PD-L1-specific ISVD comprising the amino acid sequence set forth in SEQ ID NO:6 and a CTLA4-specific ISVD comprising the amino acid sequence set forth in SEQ ID NO:20. For example, a dimer of the present disclosure may comprise the amino acid sequence of SEQ ID NO:40.

[0227] The dimer of the present disclosure can also be designated KN046.

[0228] How to use

[0229] The present disclosure provides use of a dimer in the preparation of a medicament for treating a tumor in a subject in need thereof. The present disclosure further provides a method of treating a tumor in a subject in need thereof, comprising administering to the subject an effective amount of a dimer.

[0230] In some embodiments, a subject may have been treated for a tumor with one or more currently available therapies but has not substantially responded thereto. The term "substantially unresponsive" may refer to a patient receiving or being treated with one or more currently available therapies (e.g., chemotherapy, radiation therapy, chemoradiotherapy, CTL cell therapy, EGFR tyrosine kinase inhibitor (TKI) therapy, anti-angiogenic therapy, surgery, hormonal therapy and / or biological therapy / immunotherapy, immune checkpoint inhibitor therapy, particularly standard treatment regimens for a particular tumor), where the treatment is not clinically appropriate for the patient or the patient is no longer receiving any beneficial effect from the treatment, and therefore these patients are in need of additional effective treatment.

[0231] In some embodiments, the treatment may include those for NSCLC, melanoma, esophageal squamous cell carcinoma (ESCC), NPC, or breast cancer (e.g., triple-negative breast cancer (TNBC)).

[0232] In the present disclosure, the tumor may be selected from the group consisting of NSCLC, melanoma, esophageal squamous cell carcinoma (ESCC), NPC, or breast cancer.

[0233] For example, the tumor may be selected from the group consisting of esophageal squamous cell carcinoma (ESCC) and nasopharyngeal carcinoma (NPC).

[0234] For example, the tumor may be selected from the group consisting of locally advanced or metastatic melanoma, non-keratinizing locally advanced recurrent or metastatic NPC, metastatic NSCLC, squamous and non-squamous NSCLC, recurrent or metastatic ESCC, and triple-negative breast cancer (TNBC).

[0235] For example, the tumor may be selected from the group consisting of advanced NSCLC without EGFR mutations or ALK fusions, NSCLC with EGFR exon 20 insertion mutations, PD-L1 positive NPC, and locally advanced inoperable or metastatic TNBC.

[0236] In some embodiments, the subject may be co-administered with an immune checkpoint inhibitor. For example, the dimer may be administered about 1 minute, 2 minutes, 5 minutes, 10 minutes, 20 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 12 hours, 18 hours, 1 day, 2 days, 3 days, 1 week, 2 weeks, 3 weeks, 1 month, 2 months, 3 months, 6 months, 1 year, 2 years, 3 years or more after administration of the immune checkpoint inhibitor.

[0237] In some embodiments, the subject may be substantially non-responsive to the immune checkpoint inhibitor, hi some embodiments, the immune checkpoint inhibitor may be selected from the group consisting of a PD-L1 inhibitor, a PD-1 inhibitor, and a CTLA4 inhibitor.

[0238] A subject who does not substantially respond to an immune checkpoint inhibitor may have previously responded to an immune checkpoint inhibitor, but may have become less responsive to the immune checkpoint inhibitor, or the subject may never have responded to an immune checkpoint inhibitor. An inadequate response to an immune checkpoint inhibitor means that aspects of the condition that would be expected to improve following a standard dose of the immune checkpoint inhibitor do not improve, and / or improvement occurs only when doses greater than the standard dose are administered. In some embodiments, a subject who does not substantially respond to an immune checkpoint inhibitor may have experienced or is experiencing an inadequate response to the immune checkpoint inhibitor after receiving a standard dose for at least 2 weeks, at least 3 weeks, at least 4 weeks, at least 6 weeks, or at least 12 weeks. The "standard" dose is determined by a medical professional and may depend on the subject's age, weight, health history, severity of disease, frequency of administration, etc.

[0239] In the present disclosure, the subject may be receiving chemotherapy, chemoradiotherapy, CTL cell therapy, an EGFR tyrosine kinase inhibitor (TKI), and / or an angiogenesis inhibitor.

[0240] In this disclosure, the chemotherapy may refer to any treatment of the tumor with chemical agents that kill tumor cells, shrink tumors, and alleviate signs and symptoms of cancer. For example, the chemotherapy may include first-line chemotherapy and / or second-line chemotherapy. In this disclosure, the first-line chemotherapy may refer to one or more chemotherapy regimens generally accepted by medical institutions for the initial treatment of a given type and stage of cancer. For example, the first-line chemotherapy may include platinum-based chemotherapy. In some embodiments, the first-line platinum-based chemotherapy may include chemotherapy with a platinum (P) compound (cisplatin or carboplatin).

[0241] In the present disclosure, the second-line chemotherapy may refer to one that is attempted if the first-line chemotherapy does not work sufficiently. For example, the second-line chemotherapy may include paclitaxel, docetaxel, capecitabine, and / or 5-FU.

[0242] In the present disclosure, the chemoradiotherapy (CRT, CRTx, CT-RT) may refer to a treatment that combines chemotherapy and radiotherapy.

[0243] In the present disclosure, said CTL cell therapy may refer to cytotoxic T lymphocyte therapy.

[0244] In the present disclosure, the EGFR tyrosine kinase inhibitor may refer to a substance that blocks the activity of a protein called epidermal growth factor receptor (EGFR), and may include monoclonal antibodies directed against the surface of the receptor and / or tyrosine kinase inhibitors directed against the intracellular domain of the receptor.

[0245] In the present disclosure, the angiogenesis inhibitor may refer to a substance that inhibits the growth of new blood vessels (angiogenesis).

[0246] In some embodiments, the agent or dimer may be administered intravenously, intramuscularly, subcutaneously, topically, orally, transdermally, intraperitoneally, intraorbitally, by implant, by inhalation, intrathecally, intracerebroventricularly, or intranasally. An effective amount of the agent may be administered for the prevention or treatment of a disease. The appropriate dose of the agent may be determined based on the type of disease to be treated, the type of agent, the severity and course of the disease, the individual's clinical condition, the subject's medical history and response to treatment, and the discretion of the attending physician. For example, a suitable dosage may be from about 0.1 mg or 1 mg / kg / day to about 500 mg / kg / day (e.g., about 0.1 mg / kg to about 0.3 mg / kg, about 0.1 mg / kg to about 1 mg / kg, about 0.1 mg / kg to about 3 mg / kg, about 0.1 mg / kg to about 5 mg / kg, about 0.1 mg / kg to about 10 mg / kg, about 1 mg / kg to about 5 mg / kg, about 3 mg / kg to about 5 mg / kg, about 1 mg / kg to about 3 mg / kg, about 1 mg / kg to about 500 mg / kg, or about 1 mg / kg to about 150 mg / kg); sometimes dosages may be even higher.

[0247] In some embodiments, the agent or dimer may be administered once every two weeks or once every three weeks.

[0248] The agent may be administered by any convenient route, for example, by infusion or bolus injection, by absorption through epithelial or mucocutaneous linings (e.g., oral, rectal, and intestinal mucosa, etc.), or may be administered together with other biologically active agents. Administration may be systemic or local. In some embodiments, the agent may be administered intravenously.

[0249] In certain embodiments, it may be desirable to administer the agents of the present disclosure locally to the area in need of treatment. This may be achieved, for example, but not limited to, by local infusion, topical application, injection, catheter, suppository, or implant, where the implant is a porous, non-porous, or gel-like material, including a membrane. Preferably, when administering the agents of the present disclosure, care should be taken to use materials to which proteins do not adsorb.

[0250] The drug and / or immune checkpoint inhibitor may be administered by the same route of administration or by different routes of administration.

[0251] The medicaments of the present invention can treat tumors in a subject in need thereof. Tumors include solid tumors, hematological tumors, lymphomas, etc. The tumors are advanced or metastatic tumors. In some embodiments, the tumors can be selected from the group consisting of NSCLC, melanoma, esophageal squamous cell carcinoma (ESCC), NPC, or breast cancer (e.g., triple-negative breast cancer (TNBC)).

[0252] In some cases, a tumor may not respond to treatment with an immune checkpoint inhibitor (e.g., a PD-1 antagonist and / or a PD-L1 antagonist). For example, treatment with a PD-1 antagonist and / or a PD-L1 antagonist does not result in a substantial or observable delay or inhibition of tumor progression or tumor growth. In some cases, the tumor may not have been treated with a PD-1 antagonist and / or a PD-L1 antagonist prior to administration of the dimer / composition / immunoconjugate of the present disclosure. The PD-1 antagonist may be a PD-1 blocking antibody. The PD-L1 antagonist may be a PD-L1 blocking antibody.

[0253] The tumor or tumor cell can be a tumor or tumor cell within a subject, for example, within a human or a non-human animal (e.g., a mammal). In some cases, the tumor / tumor may be unresectable. In some cases, the tumor / tumor may be metastatic (e.g., a metastatic solid tumor). In some cases, the tumor / tumor may be resistant and / or intolerant to standard treatment. For example, the tumor may be a resistant tumor, meaning a tumor that is resistant at the start of treatment or that becomes resistant during treatment.

[0254] In the present disclosure, metastatic refers to a condition in which a tumor has spread from an initial or primary site to a different or secondary site within a subject's body.

[0255] In the present disclosure, recurrence refers to the discovery of a tumor after treatment and / or a period of time during which the tumor was not detectable. The recurrent tumor may be in the same location where it first developed or in another location within the subject's body.

[0256] In the present disclosure, the mutation refers to a change in the nucleotide sequence of a genome. For example, the mutation may include a deletion, insertion, and / or substitution of nucleotides and / or components of a gene (e.g., an exon).

[0257] In the present disclosure, the dimer is administered in combination with a chemotherapeutic agent.

[0258] In the present disclosure, the chemotherapeutic agent may be any agent capable of chemotherapy. For example, the chemotherapeutic agent may include a platinum agent and / or paclitaxel. For example, the chemotherapeutic agent may include cisplatin, gemcitabine, and / or nab-paclitaxel.

[0259] For example, the tumor may comprise a recurrent or metastatic ESCC, and the subject has not been treated with CRT within 6 months and has subsequently received palliative CRT consisting of cisplatin, paclitaxel, and radiation.

[0260] For example, the tumor may include advanced NSCLC without an EGFR mutation or ALK fusion, which has progressed on first-line platinum-based chemotherapy but has not been treated with any PD-(L)1 immune checkpoint inhibitor.

[0261] For example, the tumor may comprise an NSCLC with an EGFR exon 20 insertion mutation that has failed treatment with an EGFR tyrosine kinase inhibitor (TKI).

[0262] For example, the tumor may comprise NPC and the subject has failed treatment with the first-line chemotherapy, the second-line chemotherapy, and / or an anti-PD-1 agent.

[0263] combination

[0264] In another aspect, the present disclosure provides use of a dimer of the present disclosure in combination with a chemotherapeutic agent of the present disclosure in the preparation of a medicament for treating a tumor in a subject in need thereof.

[0265] In another aspect, the present disclosure provides a dimer of the present disclosure in combination with a chemotherapeutic agent of the present disclosure for use in treating a tumor in a subject in need thereof.

[0266] In another aspect, the present disclosure provides a method of treating a tumor in a subject in need thereof, comprising administering a dimer of the present disclosure in combination with a chemotherapeutic agent of the present disclosure.

[0267] In the present disclosure, the tumor may be selected from the group consisting of solid tumors and hematological tumors, for example, the tumor may be selected from the group consisting of NSCLC and breast cancer.

[0268] For example, the tumor may be selected from the group consisting of squamous and non-squamous NSCLC and triple-negative breast cancer (TNBC). For example, the tumor may be selected from the group consisting of NSCLC with EGFR exon 20 insertion mutations and locally advanced inoperable or metastatic TNBC.

[0269] In the present disclosure, the subject may be administered an EGFR tyrosine kinase inhibitor (TKI).

[0270] In the present disclosure, the dimer may be administered at a dosing frequency of 4 times per week, 2 times per week, 1 time per week, 2 times per week, 3 times per week, 4 times per week, 5 times per week, 6 times per week, 8 times per week, or 12 times per week. For example, the dimer may be administered at a dosing frequency of once every 2 weeks.

[0271] In the present disclosure, the chemotherapeutic agent may be administered at a dosing frequency of 4 times per week, 2 times per week, once per week, once per 2 weeks, once per 3 weeks, once per 4 weeks, once per 5 weeks, once per 6 weeks, once per 8 weeks, or once per 12 weeks.

[0272] In the present disclosure, the dimer may be administered intravenously, intramuscularly, subcutaneously, topically, orally, transdermally, intraperitoneally, intraorbitally, by implantation, by inhalation, intrathecally, intracerebroventricularly, or intranasally.

[0273] In the present disclosure, the chemotherapeutic agent may be administered intravenously, intramuscularly, subcutaneously, topically, orally, transdermally, intraperitoneally, intraorbitally, by implant, by inhalation, intrathecally, intracerebroventricularly, or intranasally.

[0274] In the present disclosure, the dimer may be administered at a dose of 0.01 mg / kg to 100 mg / kg. For example, the dimer may be administered at a dose of about 1 mg / kg to about 5 mg / kg, about 3 mg / kg to about 5 mg / kg, or about 1 mg / kg to about 3 mg / kg.

[0275] In the present disclosure, the chemotherapeutic agent may be administered at a dose of 0.01 mg / kg to 10 mg / kg. For example, the platinum agent may be administered at a dose of about 1 mg / kg to about 5 mg / kg, about 3 mg / kg to about 5 mg / kg, or about 1 mg / kg to about 3 mg / kg.

[0276] In some embodiments, the dimer can be administered in combination with a platinum agent. For example, the tumor can include NSCLC with an EGFR exon 20 insertion mutation that has failed treatment with an EGFR tyrosine kinase inhibitor (TKI).

[0277] In some embodiments, the dimer can be administered in combination with paclitaxel, e.g., nab-paclitaxel. For example, the tumor can include metastatic triple-negative breast cancer (mTNBC) in which the subject has not previously been treated. For example, the tumor can include locally advanced, inoperable, or metastatic TNBC.

[0278] In another aspect, the present disclosure provides a kit comprising a dimer of the present disclosure in combination with a chemotherapeutic agent of the present disclosure.

[0279] Example

[0280] The following examples are provided to provide those of skill in the art with a complete disclosure and description of how to make and use the present invention, and are not intended to limit the scope of what the inventors regard as their invention, nor are they intended to represent all or the only experiments performed. Efforts have been made to ensure accuracy with respect to numbers used (e.g., amounts, temperatures, etc.), but some experimental error and deviation should be accounted for. Unless otherwise specified, parts are parts by weight, molecular weights are weight average molecular weights, temperatures are in degrees Celsius, and pressures are at or near atmospheric. Standard abbreviations may be used, such as bp, base pairs; kb, kilobases; pl, picoliters; s or sec, seconds; min, minutes; h or hr, hours; aa, amino acids; nt, nucleotides; im, intramuscular; ip, subperitoneal; sc, subcutaneous, etc.

[0281] Phase I study in oncology patients

[0282] This is a Phase I / II, open-label, multicenter, dose-escalation study to evaluate the safety, tolerability, pharmacokinetics, and antitumor activity of the dimer in patients with advanced solid tumors and lymphomas. Sixteen participants were estimated to be enrolled. Eligibility criteria:

[0283] Be willing and able to sign informed consent and undergo all procedures required for the study.

[0284] Histologically or cytologically confirmed solid tumors. The study subjects are patients with advanced or metastatic (unresectable) solid tumors who have progressed after the last anti-tumor treatment, who have refused or are unable to tolerate standard treatments, or who have refractory solid tumors for which standard treatments, including chemotherapy and targeted therapy, are contraindicated.

[0285] Specific tumor types in the study dose / cohort expansion phase: Melanoma: locally advanced or metastatic melanoma (unresectable) confirmed by histological examination; failure of first-line chemotherapy or first-line targeted therapy (e.g., chemotherapy, TSA-CTL cell therapy, immune checkpoint inhibitor therapy); Nasopharyngeal carcinoma: Histologically confirmed non-keratinizing locally advanced recurrent or metastatic nasopharyngeal carcinoma that has failed primary or more than primary chemotherapy including platinum agents (e.g., platinum-containing chemoradiotherapy, platinum-containing chemoradiotherapy plus adjuvant chemotherapy). NSCLC: Those for which first-line treatment (chemotherapy, anti-angiogenic drugs, immune checkpoint inhibitors) was ineffective.

[0286] Phase Ia: 1, 3, and 5 mg / kg (mg / kg) administered by intravenous (IV) infusion every 2 weeks. Phase Ib: 1, 3, or 3, 5 mg / kg (mg / kg) administered by intravenous (IV) infusion every 2 weeks, with the dose for Phase Ib determined based on the results of Phase Ia. Or 300, 500 mg / kg (mg / kg) administered every 3 weeks.

[0287] In Phase 1a, the primary endpoint is the number of participants experiencing dose-limiting toxicity (DLT). In Phase 1b, the primary endpoints are objective response rate (ORR) based on RECIST 1.1 or Lugano 2014 criteria and duration of response (DoR). Secondary endpoints include treatment-emergent adverse events (TEAEs), adverse events, and PK parameters (including but not limited to AUC0-t, Cmax, CL, Tl / 2, and Ctrough).

[0288] Treatment will continue until disease progression or unacceptable toxicity occurs. During follow-up, patients will be monitored for disease activity and safety.

[0289] Figure 2 shows the results for patients who failed immune checkpoint inhibitor therapy. The ORR was 12.5% ​​and the DCR was 63%. In the 5 mg / kg Q2W cohort (N=8), the ORR was 12.5% ​​and the DCR was 75%. Progressive disease (PD) did not occur in 14 of 16 patients with NSCLC, NPC, or melanoma.

[0290] The single agent has an acceptable safety profile.

[0291] Case 2: Preliminary efficacy and safety of KN046 plus concurrent chemoradiotherapy in esophageal squamous cell carcinoma

[0292] Background: Definitive or palliative chemoradiotherapy is used in the management of esophageal squamous cell carcinoma (ESCC). Immune checkpoint inhibitors have improved outcomes for patients with metastatic stage IV disease. Here, we report the addition of KN046, a PD-L1 / CTLA-4 bispecific antibody, to concurrent chemoradiotherapy (CRT) to characterize the safety and efficacy of this approach (ChiCTR2000031544).

[0293] Objectives and Methods: Eligible patients (Pts) with recurrent or metastatic ESCC who had not been treated with CRT within 6 months were recruited and treated with cisplatin (75 mg / m 2 IVQ3W, 4 to 6 cycles), paclitaxel (135 to 175 mg / m 2 Palliative CRT consisted of IVQ3W (4 to 6 cycles) and radiation (30-40 Gy at the investigator's discretion, according to institutional standards). KN046 at 1, 3, or 5 mg / kg was added concomitantly with chemotherapy within 7 to 14 days after completion of RT, followed by KN046 Q2W maintenance therapy. Dose-limiting toxicities (DLTs) were assessed for the first treatment cycle of KN046. Antitumor activity was assessed every 6 weeks for the first year and every 12 weeks thereafter according to RECIST 1.1.

[0294] Results: As of June 30, 2020, 18 subjects were enrolled and treated with KN046 (1 mg / kg, 3 patients; 3 mg / kg, n=11; 5 mg / kg, 4 patients). The median KN046 exposure was 11.5 weeks. No DLTs were reported. Grade 3 KN046-related adverse events were observed in three patients (16.7%) (one case of grade 3 pneumonia resolved with steroids and antibiotic therapy, one case of grade 3 colitis resolved with antibiotic therapy alone, and one case of grade 3 colitis resolved with steroids and antibiotic therapy). In the 3 mg / kg group, five of nine efficacy-evaluable patients (55.6%) achieved an objective response, resulting in a disease control rate of 100%; 8 of nine patients (88.9%) experienced further tumor regression after initiating KN046 treatment.

[0295] Conclusions: The addition of KN046 to CRT was well tolerated and showed promising efficacy signals in recurrent or metastatic ESCC. This pilot study allows further investigation of this novel treatment, combining KN046 with CRT, in poor-prognosis disease.

[0296] Example 3: Phase II study of KN046 in patients with metastatic non-small cell lung cancer (NSCLC)

[0297] Background: KN046 is a novel bispecific antibody that blocks PD-L1 interactions with PD-1 and CTLA-4 interactions with CD80 / CD86. This multi-cohort, single-arm phase II study evaluates the preliminary safety and efficacy of KN046 in patients with metastatic non-small cell lung cancer (NSCLC).

[0298] Study Methods: Eligible patients (pts) had advanced NSCLC without EGFR mutations or ALK fusions, had progressed on first-line platinum-based chemotherapy, but had not been treated with a PD-(L)1 immune checkpoint inhibitor. All pts received KN046 3 mg / kg (Cohort A) or 5 mg / kg (Cohort B) intravenously Q2W every 8 weeks. Efficacy was assessed by the investigator per RECIST 1.1, and safety and tolerability were assessed per NCI-CTCAE v5.0.

[0299] Results: As of July 27, 2020, 30 patients were enrolled in Cohort A and 33 in Cohort B. The median age was 59 years, 51 / 12 males / 12 females, PS 0 / 19 / 54, and 23 / 40 squamous non-small cell lung cancer / non-squamous non-small cell lung cancer cases. Grade 3 or higher adverse events were observed in 21 patients (33.3%), 16 patients (25.4%) related to treatment, 34 patients (54.0%) with irAEs, and 11 patients (17.5%) with grade 3 or higher irAEs. Adverse events occurring in ≥10% of patients included infusion-related reactions (16, 25.4%), anemia (14, 22.2%), rash (13, 20.6%), hyperglycemia (12, 19.0%), liver dysfunction (10, 15.9%), hypothyroidism (10, 15.9%), increased alanine aminotransferase (8, 12.7%), asthenia (8, 12.7%), increased aspartate aminotransferase (7, 11.1%), and pruritus (7, 11.1%). The safety profile was comparable between the two cohorts.

[0300] As of the cutoff date, 24 patients (37.5%) continued to receive the study drug, and 39 patients (60.9%) discontinued due to disease progression (n=27), AEs (n=7), noncompliance (n=4), and one death. The median duration of drug exposure was 14 weeks (range, 2-56 weeks). The ORR and DCR were 10.7% and 71.4% in 56 evaluable patients. The median PFS was 3.7 (2.9, 7.3). The 6- and 12-month PFS rates (95% CI) were 36.6% (23.0, 50.4) and 18.3% (6.2, 35.5), respectively. The 6- and 12-month OS rates (95% CI) were 86.9% (74.2, 93.6) and 60.7% (36.0, 78.4). In patients with squamous cell NSCLC, the median PFS was 7.3 (3.7, Nebraska, USA), the 9-month PFS rate (95% CI) was 46.6% (19.0, 70.3), and the 6-month and 12-month OS rates (95% CI) were 88.2% (60.2, 96.9) and 52.9% (13.2, 81.9), respectively.

[0301] Conclusions: The bispecific antibody KN046 was well tolerated and effective as second-line therapy for advanced NSCLC. KN046 showed promising PFS and OS effects in squamous cell carcinoma.

[0302] Clinical trial information: NCT03838848

[0303] Example 4: Advice on Breakthrough Therapy Designation Applications (BTDR)

[0304] This document will serve as the basis for the Office's opinion on whether a Breakthrough Therapy Designation (BTD) application is appropriate, whether the drug may currently be too rudimentary, or may not currently meet the BTD criteria.

[0305] 1. Provide information related to whether the indication is serious and life-threatening. Briefly describe the product's indication and target disease.

[0306] KN 046 in combination with a platinum agent is indicated for the treatment of NSCLC with EGFR exon 20 insertion mutations.

[0307] 2. Briefly describe the drug, its mechanism of action (if known), and its relationship to existing treatments.

[0308] KN046 is a PD-L1 / CTLA-4 bispecific antibody that blocks the PD1 / PD-L1 and CTLA-4 pathways.

[0309] 3. Outline available treatments, if any.

[0310] Approximately 0.5%-4% of EGFRmut NSCLCs harbor exon 20 insertions. Approved EGFR tyrosine kinase inhibitors (TKIs) are ineffective, with an objective response rate (ORR) of 16.1%.

[0311] With chemotherapy with or without TKIs, the ORR is 27.5%. PFS is approximately 5 months and OS is approximately 16 months with available treatments. New treatments are needed for this subtype of NSCLC. [Table 3]

[0312] 4. Provide information on preliminary clinical evidence*, including study design, study endpoints, treatment arms, and number of subjects enrolled.

[0313] Study KN046-202 (NCT0405453l) is an open-label, parallel-group, phase II study evaluating the efficacy and safety of KN046 in combination with a platinum-based chemotherapy as first-line treatment for squamous and non-squamous NSCLC. Enrollment was permitted for patients with NSCLC who do not have EGFR-sensitizing mutations.

[0314] As of September 3, 2020, nine patients with EGFR exon 20 insertion mutations had been enrolled and treated with KN046 in combination with carboplatin and pemetrexed. The response rate was 55.5% (5 / 9, 95% CI 21.2%-86.3%), and the disease control rate was 88.9% (8 / 9) (Figure 3).

[0315] For example, for oncology / hematology products, preliminary clinical evidence may include response rate, duration of response, and extent of prior treatment.

[0316] Example 5: Advice on Breakthrough Therapy Designation Applications (BTDR)

[0317] This document will serve as the basis for the Office's opinion on whether a Breakthrough Therapy Designation (BTD) application is appropriate, whether the drug may currently be too rudimentary, or may not currently meet the BTD criteria.

[0318] 1. Provide information related to whether the indication is serious and life-threatening. Briefly describe the product's indication and target disease.

[0319] The drug is indicated for PD-L1 positive nasopharyngeal carcinoma (NPC).

[0320] 2. Briefly describe the drug, its mechanism of action (if known), and its relationship to existing treatments.

[0321] KN046 is a PD-L1 / CTLA-4 bispecific antibody that blocks the PD1 / PD-L1 and CTLA-4 pathways.

[0322] 3. Outline available treatments, if any.

[0323] Platinum-based chemotherapy (e.g., cisplatin / gemcitabine) is the standard first-line treatment, with a median progression-free survival (PFS) of 7 months and a median overall survival (OS) of 29.1 months. Second-line treatments include paclitaxel, docetaxel, capecitabine or 5-FU, and methotrexate, with a median OS of less than 12 months. Preliminary data on the efficacy of ipilimumab and nivolumab in second-line and later-line settings showed 12-month OS rates of 63% and 62%, respectively.

[0324] 4. Provide information on preliminary clinical evidence, including study design, study endpoints, treatment arms, and number of subjects enrolled.

[0325] KN046-CHN-001 is a Phase Ia / Ib dose-escalation study in patients with advanced solid tumors. A total of 59 NPC patients were enrolled in the study. All patients had failed at least first-line systemic therapy, 24 (40.7%) had failed prior second-line systemic therapy, and 25 (42.4%) had failed anti-PD-1 agents.

[0326] In the anti-PD-1 naive population, 29 patients were evaluable for efficacy, and a response rate of 24.1% (7 / 29) was observed. Among the 29 patients, 20 patients were PD-L1 positive (defined as PD-L1 expression on immune cells >10% using the SP263 assay), resulting in a response rate of 30%.

[0327] With a median follow-up of 13 months and a minimum follow-up of 5.2 months, overall survival was not reached. The 12-month OS rates in the anti-PD-1 naïve and anti-PD-1 pretreated populations were 71.5% (95% CI 50.1%-85%) and 74.3% (95% CI 47%-89%), respectively.

[0328] For example, for oncology / hematology products, preliminary clinical evidence may include response rate, duration of response, and extent of prior treatment.

[0329] Example 6 Preliminary safety, tolerability, and efficacy results of KN046 (anti-PD-L1 / CTLA-4 bispecific antibody) in combination with Nab-paclitaxel in metastatic triple-negative breast cancer (mTNBC)

[0330] background:

[0331] Triple-negative breast cancer (TNBC) has the poorest prognosis compared with other subtypes of invasive breast cancer. The IMpassionl-1 and Keynote-355 trials in patients with PD-L1-positive TNBC demonstrated improved clinical outcomes when anti-PD-L1 agents were added to first-line chemotherapy.

[0332] KN046 is a novel bispecific antibody that blocks the PD-L1 and CTLA-4 pathways. Here, we report interim results from an ongoing phase II study of KN046 in combination with nab-paclitaxel in patients (pts) with mTNBC.

[0333] Test Method:

[0334] This study enrolled patients with previously untreated locally advanced, inoperable, or metastatic TNBC. Eligible patients received two doses of nab-paclitaxel plus KN046 (DL1: KN046 3 mg / kg Q2W or DL2: KN046 5 mg / kg Q2W). Tumor response was assessed Q8W by Resist 1.1. PD-L1 expression was measured using the SP142 assay.

[0335] result:

[0336] As of October 29, 2020, 27 patients had been enrolled in DL1 (n=16) and DL2 (n=11). Twelve patients continued on the study and 15 discontinued treatment due to disease progression (n=8), death (n=1), adverse events (n=3), and other reasons (n=3). Patients tolerated the KN046 and nab-paclitaxel combination well. No KN046-related adverse events (TRAEs) leading to death were observed. Adverse events were observed in 27 patients (100%), with 13 (48.1%) experiencing grade 3 or higher adverse events. Eleven patients (40.7%) experienced immune-related adverse events (irAEs), including two patients with grade 3 immune-mediated liver injury and one patient with grade 3 rash. The most common adverse events (≥20%) with this combination therapy were increased AST (48%), increased ALT (48%), fever (33%), decreased neutrophil count (30%), anemia (26%), rash (26%), and decreased white blood cell count (26%). Grade ≥3 adverse events (≥15%) were decreased neutrophil count (26%), decreased white blood cell count (22%), and increased AST (15%).

[0337] The median PFS was 7.33 (4.04, NE, USA) months, with a 12-month PFS rate of 38.3% (95% CI 19.7-74.6%). Median OS was not reached, with a 12-month OS rate of 80% (95% CI 61.4-100%).

[0338] In patients with PD-L1-positive (IC PD-L1 ≥ 1%) or unknown PD-L1 status (PD-L1 < 1%), the median PFS was 7.36 months (95% CI 7.36, NE), with a 12-month PFS rate of 49.4% (95% CI 20.6-100%). The 12-month OS rate was 90.9% (95% CI 75.1-100%).

[0339] Conclusions: KN046 plus nab-paclitaxel combination therapy was well tolerated and demonstrated favorable clinical efficacy in PD-L1-positive TNBC. Preliminary overall survival data are encouraging.

[0340] Clinical trial information: NCT03872791

[0341] While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. The present invention is not intended to be limited by the specific examples provided herein. While the present invention has been described with reference to the above specification, the description and illustration of the embodiments herein are not intended to be construed in a limiting sense. Numerous variations, changes, and substitutions will occur to those skilled in the art without departing from the invention. Furthermore, it is to be understood that all aspects of the present invention are not limited to the specific depictions, configurations, or relative proportions set forth herein, which depend upon a variety of conditions and variables. It is to be understood that various alternatives to the embodiments of the present invention described herein may be used in practicing the present invention. It is therefore contemplated that the present invention also embraces such alternatives, modifications, variations, or equivalents. The following claims define the scope of the invention, and it is intended that methods and structures within the scope of these claims and their equivalents be covered thereby. The present disclosure includes, for example, the embodiments described in the following sections. [Section 1] 1. Use of a dimer in the preparation of a medicament for treating a tumor, wherein the dimer is formed by two polypeptide chains, each of the two polypeptide chains comprising an antibody Fc subunit, and the dimer comprises two or more immunoglobulin single variable domains (ISVDs), at least one of the ISVDs being specific for PD-L1 and at least one of the ISVDs being specific for CTLA4. [Section 2] The use of item 1, wherein at least one of the two polypeptide chains comprises both a PD-L1-specific ISVD and a CTLA4-specific ISVD. [Section 3] The use of any one of items 1 to 2, wherein each of the two polypeptide chains comprises both a PD-L1-specific ISVD and a CTLA4-specific ISVD. [Section 4] 4. The use of any one of items 1 to 3, wherein for one or both of the two polypeptide chains, the ISVD specific for PD-L1 is fused, optionally via a linker, to the ISVD specific for CTLA4. [Section 5] The use according to any one of items 1 to 4, wherein one or both of the two polypeptide chains are: The ISVD specific for PD-L1 is fused, optionally via a linker, to the ISVD specific for CTLA4; and the ISVD specific for CTLA4 is fused, optionally via a linker, to the antibody Fc subunit. [Section 6] Item 6. The use according to any one of items 1 to 5, wherein one or both of the two polypeptide chains are: the C-terminus of the ISVD specific for PD-L1 is fused, optionally via a linker, to the N-terminus of the ISVD specific for CTLA4; and The C-terminus of the ISVD specific for CTLA4 is fused, optionally via a linker, to the N-terminus of the antibody Fc subunit. [Section 7] Item 7. The use according to any one of items 1 to 6, wherein one or both of the two polypeptide chains are: the ISVD specific for PD-L1 is fused to the ISVD specific for CTLA4, optionally via a linker; and The ISVD specific for PD-L1 is fused to the antibody Fc subunit, optionally via a linker. [Section 8] 8. The use of claim 7, wherein for one or both of the two polypeptide chains: the C-terminus of the ISVD specific for CTLA4 is fused, optionally via a linker, to the N-terminus of the ISVD specific for PD-L1; and The C-terminus of the PD-L1-specific ISVD is fused, optionally via a linker, to the N-terminus of the antibody Fc subunit. [Section 9] The use according to any one of Items 1 to 8, wherein the antibody Fc subunit is derived from an IgG Fc subunit. [Section 10] The use of item 9, wherein the IgG is human IgG1. [Section 11] Item 11. The use according to any one of Items 1 to 10, wherein the antibody Fc subunit comprises the amino acid sequence set forth in any one of SEQ ID NOs: 35, 38, and 39. [Section 12] The use of any one of items 1 to 11, wherein the PD-L1-specific ISVD is capable of binding to the human PD-L1 N-terminal IgV domain. [Section 13] Item 13. The use of any one of Items 1 to 12, wherein the PD-L1-specific ISVD can bind to residues 154, Y56, E58, Q66, and / or R113 of the human PD-L1 N-terminal IgV domain, and the human PD-L1 N-terminal IgV domain comprises the amino acid sequence set forth in SEQ ID NO: 64. [Section 14] The use of clause 13, wherein the PD-L1-specific ISVD can further bind to residues D61, N63, V68, M115, S117, Y123, and / or R125 of the human PD-L1 N-terminal IgV domain, wherein the human PD-L1 N-terminal IgV domain comprises the amino acid sequence set forth in SEQ ID NO: 64. [Section 15] The use of any one of Items 1 to 14, wherein the PD-L1-specific ISVD can bind to a conformational epitope in the human PD-L1 N-terminal IgV domain, the conformational epitope comprising residues 154, Y56, E58, Q66, and R113 in the human PD-L1 N-terminal IgV domain, and the human PD-L1 N-terminal IgV domain comprises the amino acid sequence set forth in SEQ ID NO: 64. [Section 16] Item 16. The use of any one of Items 1 to 15, wherein the PD-L1-specific ISVD can bind to a conformational epitope in the human PD-L1 N-terminal IgV domain, the conformational epitope comprising residues 154, Y56, E58, Q66, R113, D61, N63, V68, M115, S117, Y123, and R125 of the human PD-L1 N-terminal IgV domain, and the human PD-L1 N-terminal IgV domain comprises the amino acid sequence set forth in SEQ ID NO: 64. [Section 17] Item 17. The use according to any one of items 1 to 16, wherein the PD-L1-specific ISVD can block the binding of PD-L1 to PD1. [Section 18] Item 18. The use according to any one of items 1 to 17, wherein the PD-L1-specific ISVD can block the binding of PD-L1 to CD80. [Section 19] The use of any one of Items 1 to 18, wherein the PD-L1 cross-specific ISVD competes for binding to PD-L1 with a reference anti-PD-L1 antibody, and the reference anti-PD-L1 antibody comprises a heavy chain CDR3 comprising the amino acid sequence set forth in SEQ ID NO:1. [Section 20] The use of clause 19, wherein the reference anti-PD-L1 antibody comprises a heavy chain CDR3 comprising the amino acid sequence set forth in any one of SEQ ID NOs: 5 and 9. [Section 21] The use of any one of items 19 to 20, wherein the reference anti-PD-L1 antibody comprises a heavy chain CDR1 comprising the amino acid sequence set forth in SEQ ID NO:2. [Section 22] 22. The use of any one of Aspects 19 to 21, wherein the reference anti-PD-L1 antibody comprises a heavy chain CDR1 comprising the amino acid sequence set forth in any one of SEQ ID NOs: 3 and 7. [Section 23] 23. The use of any one of items 19 to 22, wherein the reference anti-PD-L1 antibody comprises a heavy chain CDR2 comprising the amino acid sequence set forth in any one of SEQ ID NOs: 4, 8, and 11. [Section 24] 24. The use of any one of items 19 to 23, wherein the reference anti-PD-L1 antibody is an ISVD specific for PD-L1. [Section 25] 25. The use of any one of items 19 to 24, wherein the reference anti-PD-L1 antibody comprises a heavy chain variable domain comprising the amino acid sequence set forth in any one of SEQ ID NOs: 6, 10, 12, 13, 14, and 15. [Section 26] 26. The use of any one of items 19 to 25, wherein the reference anti-PD-L1 antibody comprises a heavy chain variable domain comprising the amino acid sequence set forth in SEQ ID NO:6. [Section 27] Item 27. The use of any one of Items 1 to 26, wherein the PD-L1-specific ISVD comprises a heavy chain CDR3 comprising the amino acid sequence set forth in SEQ ID NO:1. [Section 28] Item 28. The use of any one of Items 1 to 27, wherein the PD-L1-specific ISVD comprises a heavy chain CDR3 comprising the amino acid sequence set forth in any one of SEQ ID NOs: 5 and 9. [Section 29] Item 29. The use of any one of Items 1 to 28, wherein the PD-L1-specific ISVD comprises a heavy chain CDR1 comprising the amino acid sequence set forth in SEQ ID NO:2. [Section 30] 30. The use of any one of items 1 to 29, wherein the PD-L1-specific ISVD comprises a heavy chain CDR1 comprising the amino acid sequence set forth in any one of SEQ ID NOs: 3 and 7. [Section 31] The use of any one of items 1 to 30, wherein the PD-L1-specific ISVD comprises a heavy chain CDR2 comprising the amino acid sequence set forth in any one of SEQ ID NOs: 4, 8, and 11. [Section 32] Item 32. The use of any one of Items 1 to 31, wherein the PD-L1-specific ISVD comprises a heavy chain variable domain comprising an amino acid sequence set forth in any one of SEQ ID NOs: 6, 10, 12, 13, 14, and 15. [Section 33] Item 33. The use of any one of Items 1 to 32, wherein the PD-L1-specific ISVD comprises a heavy chain variable domain comprising the amino acid sequence set forth in SEQ ID NO:6. [Section 34] Item 34. The use according to any one of Items 1 to 33, wherein the ISVD specific for CTLA4 is capable of specifically binding to human CTLA4. [Section 35] Item 35. The use according to any one of items 1 to 34, wherein the ISVD specific to CTLA4 can block the binding of CTLA4 to CD80. [Section 36] Item 36. The use according to any one of items 1 to 35, wherein the ISVD specific to CTLA4 can block the binding of CTLA4 to CD86. [Section 37] 37. The use of any one of items 1 to 36, wherein the ISVD specific to CTLA4 cross-competes for binding to CTLA4 with a reference anti-CTLA4 antibody, and the reference anti-CTLA4 antibody comprises a heavy chain CDR3 comprising the amino acid sequence set forth in SEQ ID NO: 19. [Section 38] 38. The use of paragraph 37, wherein the reference anti-CTLA4 antibody comprises a heavy chain CDR1 comprising the amino acid sequence set forth in SEQ ID NO: 17. [Section 39] 39. The use of any one of items 37 to 38, wherein the reference anti-CTLA4 antibody comprises a heavy chain CDR2 comprising the amino acid sequence set forth in SEQ ID NO:16. [Section 40] 40. The use of any one of items 37 to 39, wherein the reference anti-CTLA4 antibody comprises a heavy chain CDR2 comprising the amino acid sequence set forth in any one of SEQ ID NOs: 18, 21, and 23. [Section 41] 41. The use according to any one of items 37 to 40, wherein the reference anti-CTLA4 antibody is an ISVD specific for CTLA4. [Section 42] 42. The use of any one of items 37 to 41, wherein the reference anti-CTLA4 antibody comprises a heavy chain variable domain comprising the amino acid sequence set forth in any one of SEQ ID NOs: 20, 22, and 24 to 32. [Section 43] 43. The use of any one of items 37 to 42, wherein the reference anti-CTLA4 antibody comprises a heavy chain variable domain comprising the amino acid sequence set forth in SEQ ID NO:20. [Section 44] Item 44. The use according to any one of Items 1 to 43, wherein the ISVD specific to CTLA4 comprises a heavy chain CDR3 comprising the amino acid sequence set forth in SEQ ID NO:19. [Section 45] Item 45. The use according to any one of Items 1 to 44, wherein the ISVD specific to CTLA4 comprises a heavy chain CDR1 comprising the amino acid sequence set forth in SEQ ID NO:17. [Section 46] Item 46. The use according to any one of Items 1 to 45, wherein the ISVD specific to CTLA4 comprises a heavy chain CDR2 comprising the amino acid sequence set forth in SEQ ID NO:16. [Section 47] Item 47. The use according to any one of Items 1 to 46, wherein the ISVD specific to CTLA4 comprises a heavy chain CDR2 comprising an amino acid sequence set forth in any one of SEQ ID NOs: 18, 21, and 23. [Section 48] Item 48. The use according to any one of Items 1 to 47, wherein the ISVD specific to CTLA4 comprises a heavy chain variable domain comprising an amino acid sequence set forth in any one of SEQ ID NOs: 20, 22, and 24 to 32. [Section 49] Item 49. The use according to any one of Items 1 to 48, wherein the ISVD specific to CTLA4 comprises a heavy chain variable domain comprising the amino acid sequence set forth in SEQ ID NO:20. [Section 50] Item 50. The use according to any one of Items 1 to 49, wherein the dimer is a homodimer. [Section 51] Item 51. The use according to any one of Items 4 to 50, wherein the linker comprises an amino acid sequence set forth in any one of SEQ ID NOs: 33 to 34. [Section 52] Item 52. The use according to any one of Items 1 to 51, wherein one or both of the two polypeptide chains comprises an amino acid sequence set forth in any one of SEQ ID NOs: 40 to 43, 46, 48, and 50. [Section 53] Item 53. The use according to any one of Items 1 to 52, wherein one or both of the two polypeptide chains comprises the amino acid sequence set forth in SEQ ID NO: 40. [Section 54] Item 54. The use of any one of items 1 to 53, wherein the dimer is capable of blocking the binding of PD-L1 to PD-1. [Section 55] Item 55. The use of any one of items 1 to 54, wherein the dimer is capable of blocking the binding of PD-L1 to CD80. [Section 56] Item 56. The use of any one of items 1 to 55, wherein the dimer is capable of blocking the binding of CTLA4 to CD80. [Section 57] Item 57. The use of any one of items 1 to 56, wherein the dimer is capable of blocking the binding of CTLA4 to CD86. [Section 58] Item 58. The use according to any one of items 1 to 57, wherein the tumor is selected from the group consisting of NSCLC, melanoma, esophageal squamous cell carcinoma (ESCC), NPC, and breast cancer. [Section 59] Item 59. The use according to any one of items 1 to 58, wherein the tumor is selected from the group consisting of esophageal squamous cell carcinoma (ESCC) and nasopharyngeal carcinoma (NPC). [Section 60] Item 60. The use according to any one of items 1 to 59, wherein the subject suffering from the tumor is administered an immune checkpoint inhibitor. [Section 61] 61. The use of paragraph 60, wherein the subject has substantially failed to respond to the immune checkpoint inhibitor. [Section 62] Item 62. The use according to any one of items 60 to 61, wherein the immune checkpoint inhibitor is selected from the group consisting of: [Section 63] 63. The use according to any one of items 60 to 62, wherein the subject is receiving chemotherapy, chemoradiotherapy, CTL cell therapy, an EGFR tyrosine kinase inhibitor (TKI), and / or an angiogenesis inhibitor. [Section 64] 64. The use of paragraph 63, wherein the chemotherapy comprises first-line chemotherapy and / or second-line chemotherapy. [Section 65] 65. The use of paragraph 64, wherein the second line chemotherapy comprises paclitaxel, docetaxel, capecitabine and / or 5-FU. [Section 66] Item 66. The use according to any one of items 1 to 65, wherein the tumor is selected from the group consisting of locally advanced or metastatic melanoma, non-keratinizing locally advanced recurrent or metastatic NPC, metastatic NSCLC, squamous and non-squamous NSCLC, recurrent or metastatic ESCC, and triple-negative breast cancer (TNBC). [Section 67] Item 67. The use according to any one of items 1 to 66, wherein the tumor is selected from the group consisting of advanced NSCLC without EGFR mutation or ALK fusion, NSCLC with EGFR exon 20 insertion mutation, PD-L1-positive NPC, and locally advanced inoperable or metastatic TNBC. [Section 68] Item 68. The use of any one of items 1 to 67, wherein the dimer is administered in combination with a chemotherapeutic agent. [Section 69] 69. The use of paragraph 68, wherein the chemotherapeutic agent comprises a platinum doublet and / or paclitaxel. [Section 70] Item 69. The use of any one of items 68 to 69, wherein the chemotherapeutic agent comprises cisplatin, gemcitabine and / or nab-paclitaxel. [Section 71] A method for treating a tumor in a subject in need thereof, comprising administering to the subject an effective amount of the dimer according to any one of items 1 to 70. [Section 72] 72. The use of clause 71, wherein the tumor is selected from the group consisting of NSCLC, melanoma, esophageal squamous cell carcinoma (ESCC), NPC, and breast cancer. [Section 73] 73. The use according to any one of clauses 71 to 72, wherein the tumor is selected from the group consisting of esophageal squamous cell carcinoma (ESCC) and nasopharyngeal carcinoma (NPC). [Section 74] Item 74. The use according to any one of Items 71 to 73, wherein the subject is administered an immune checkpoint inhibitor. [Section 75] 75. The use of paragraph 74, wherein the subject has substantially failed to respond to the immune checkpoint inhibitor. [Section 76] Item 76. The use according to any one of items 74 to 75, wherein the immune checkpoint inhibitor is selected from the group consisting of: [Section 77] 77. The use according to any one of items 71 to 76, wherein the subject is receiving chemotherapy, chemoradiotherapy, CTL cell therapy, an EGFR tyrosine kinase inhibitor (TKI), and / or an angiogenesis inhibitor. [Section 78] 78. The use of clause 77, wherein the chemotherapy comprises first-line chemotherapy and / or second-line chemotherapy. [Section 79] 79. The use of paragraph 78, wherein the second line chemotherapy comprises paclitaxel, docetaxel, capecitabine and / or 5-FU. [Section 80] 80. The use of any one of clauses 71 to 79, wherein the tumor is selected from the group consisting of locally advanced or metastatic melanoma, non-keratinizing locally advanced recurrent or metastatic NPC, metastatic NSCLC, squamous and non-squamous NSCLC, recurrent or metastatic ESCC and triple-negative breast cancer (TNBC). [Section 81] 81. The use according to any one of items 1 to 80, wherein the tumor is selected from the group consisting of advanced NSCLC without EGFR mutation or ALK fusion, NSCLC with EGFR exon 20 insertion mutation, NPC with PD-L 71 expression positive, and locally advanced inoperable or metastatic TNBC. [Section 82] 82. The use of any one of paragraphs 71 to 81, wherein the dimer is administered in combination with a chemotherapeutic agent. [Section 83] 83. The use of paragraph 82, wherein the chemotherapeutic agent comprises a platinum doublet and / or paclitaxel. [Section 84] Item 84. The use of any one of items 82 to 83, wherein the chemotherapeutic agent comprises cisplatin, gemcitabine and / or nab-paclitaxel. [Section 85] Item 85. The method according to any one of Items 71 to 84, wherein the effective amount of the dimer is a dose of 1 mg / kg to 5 mg / kg. [Section 86] Item 86. The method of item 85, wherein the dose is 1 mg / kg to 3 mg / kg. [Section 87] Item 86. The method of item 85, wherein the dose is 3 mg / kg to 5 mg / kg. [Section 88] 88. The method of any one of paragraphs 71 to 87, wherein the dimer is administered once every two weeks or once every three weeks. [Section 89] Item 89. The method of any one of Items 71 to 88, wherein the dimer is administered by intravenous administration. [Section 90] 71. Use of a dimer according to any one of paragraphs 1 to 70 in combination with a chemotherapeutic agent according to any one of paragraphs 68 to 70 in the preparation of a medicament for treating a tumor. [Section 91] 91. The use of paragraph 90, wherein the tumor is selected from the group consisting of solid tumors and hematological tumors. [Section 92] 92. The use of any one of paragraphs 90 to 91, wherein the tumor comprises NSCLC and / or breast cancer. [Section 93] 93. The use according to any one of items 90 to 92, wherein the subject suffering from the tumor is administered an EGFR tyrosine kinase inhibitor (TKI). [Section 94] 94. The use of any one of clauses 90 to 93, wherein the tumor is selected from the group consisting of squamous and non-squamous NSCLC and triple-negative breast cancer (TNBC). [Section 95] Item 95. The use of any one of items 90 to 94, wherein the tumor is selected from the group consisting of NSCLC with EGFR exon 20 insertion mutation and locally advanced inoperable or metastatic TNBC. [Section 96] 96. The use of any one of paragraphs 90 to 95, wherein the dimer is administered at an administration frequency of 4 times a week, 2 times a week, once a week, once every 2 weeks, once every 3 weeks, once every 4 weeks, once every 5 weeks, once every 6 weeks, once every 8 weeks, or once every 12 weeks. [Section 97] Item 97. The use according to any one of items 90 to 96, wherein the platinum-based drug is administered at a frequency of 4 times a week, 2 times a week, once a week, once every 2 weeks, once every 3 weeks, once every 4 weeks, once every 5 weeks, once every 6 weeks, once every 8 weeks, or once every 12 weeks. [Section 98] 98. The use of any one of paragraphs 90 to 97, wherein the dimer is administered intravenously, intramuscularly, subcutaneously, topically, orally, transdermally, intraperitoneally, intraorbitally, by implantation, by inhalation, intrathecally, intracerebroventricularly, or intranasally. [Section 99] 99. The use of any one of paragraphs 90 to 98, wherein the chemotherapeutic agent is administered intravenously, intramuscularly, subcutaneously, topically, orally, transdermally, intraperitoneally, intraorbitally, by implantation, by inhalation, intrathecally, intracerebroventricularly, or intranasally. [Section 100] Item 99. The use of any one of items 90 to 99, wherein the dimer is administered at a dose of 0.01 mg / kg to 100 mg / kg. [Section 101] Item 101. The use according to any one of items 90 to 100, wherein the chemotherapeutic agent is administered at a dose of 0.01 mg / kg to 100 mg / kg. [Section 102] A kit comprising an effective amount of the dimer according to any one of Items 1 to 70 and the chemotherapeutic agent according to any one of Items 68 to 70.

Claims

1. 1. A dimer for use in treating a tumor in a subject in need thereof, comprising: the dimer is formed by two polypeptide chains, each of the two polypeptide chains comprising an antibody Fc subunit, the dimer comprising two immunoglobulin single variable domains (ISVDs), one of the ISVDs being specific for PD-L1 and the other of the ISVDs being specific for CTLA4, dimer, where: the ISVD specific for PD-L1 comprises a heavy chain variable domain comprising the amino acid sequence set forth in SEQ ID NO:6; The ISVD specific for CTLA4 comprises a heavy chain variable domain comprising the amino acid sequence set forth in SEQ ID NO: 20; For both of the two polypeptide chains: the C-terminus of the ISVD specific for PD-L1 is fused via a linker to the N-terminus of the ISVD specific for CTLA4; and the C-terminus of the ISVD specific for CTLA4 is fused to the N-terminus of the antibody Fc subunit via a linker; The subject has been administered chemotherapy, chemoradiotherapy, CTL cell therapy, an EGFR tyrosine kinase inhibitor (TKI), and / or an angiogenesis inhibitor.

2. The dimer of claim 1 , wherein the antibody Fc subunit is derived from an IgG Fc subunit.

3. The dimer of claim 2 , wherein the IgG is human IgG1.

4. The dimer according to any one of claims 1 to 3, wherein the antibody Fc subunit comprises an amino acid sequence set forth in any one of SEQ ID NOs: 35, 38 and 39.

5. The dimer according to any one of claims 1 to 4, wherein the dimer is a homodimer.

6. 6. The dimer according to any one of claims 1 to 5, wherein one or both of the two polypeptide chains comprises the amino acid sequence set forth in SEQ ID NO:

40.

7. The dimer of any one of claims 1 to 6, wherein the tumor is selected from the group consisting of NSCLC, melanoma, esophageal squamous cell carcinoma (ESCC), NPC and breast cancer.

8. The dimer of any one of claims 1 to 7, wherein the tumor is selected from the group consisting of esophageal squamous cell carcinoma (ESCC) and nasopharyngeal carcinoma (NPC).

9. The dimer of any one of claims 1 to 8, wherein the subject suffering from the tumor is administered an immune checkpoint inhibitor.

10. 10. The dimer of claim 9, wherein the subject has substantially failed to respond to the immune checkpoint inhibitor.

11. The dimer according to claim 9 or 10, wherein the immune checkpoint inhibitor comprises one or any combination selected from the group consisting of a PD-L1 inhibitor, a PD-1 inhibitor, and a CTLA4 inhibitor.

12. The dimer of any one of claims 1 to 11, wherein said chemotherapy comprises first-line chemotherapy and / or second-line chemotherapy.

13. The dimer of claim 12, wherein the second line chemotherapy comprises paclitaxel, docetaxel, capecitabine and / or 5-FU.

14. 14. The dimer of any one of claims 1 to 13, wherein the tumor is selected from the group consisting of locally advanced or metastatic melanoma, non-keratinizing locally advanced recurrent or metastatic NPC, metastatic NSCLC, squamous and non-squamous NSCLC, recurrent or metastatic ESCC and triple-negative breast cancer (TNBC).

15. 15. The dimer of any one of claims 1 to 14, wherein the tumor is selected from the group consisting of advanced NSCLC without EGFR mutation or ALK fusion, NSCLC with EGFR exon 20 insertion mutation, NPC with positive PD-L1 expression, and locally advanced inoperable or metastatic TNBC.

16. The dimer of any one of claims 1 to 15, wherein the dimer is administered in combination with a chemotherapeutic agent.

17. 17. The dimer of claim 16, wherein the chemotherapeutic agent comprises a platinum doublet and / or paclitaxel.

18. 18. The dimer of claim 16 or 17, wherein the chemotherapeutic agent comprises cisplatin, gemcitabine and / or nab-paclitaxel.

19. 19. The dimer according to any one of claims 1 to 18, wherein the dimer is for treating tumors at an effective dose of 1 mg / kg to 5 mg / kg.

20. 20. The dimer of claim 19, wherein the dose is from 1 mg / kg to 3 mg / kg.

21. 20. The dimer of claim 19, wherein the dose is 3 mg / kg to 5 mg / kg.

22. The dimer of any one of claims 1 to 21, wherein the subject suffering from the tumor is administered an EGFR tyrosine kinase inhibitor (TKI).

23. The dimer of any one of claims 1 to 22, wherein the dimer is administered at a frequency of four times a week, twice a week, once a week, once every two weeks, once every three weeks, once every four weeks, once every five weeks, once every six weeks, once every eight weeks, or once every 12 weeks.

24. 24. The dimer of claim 23, wherein the dimer is administered at a dosing frequency of once every two weeks or once every three weeks.

25. The dimer of any one of claims 1 to 24, wherein the dimer is administered intravenously, intramuscularly, subcutaneously, topically, orally, transdermally, intraperitoneally, intraorbitally, by implantation, by inhalation, intrathecally, intracerebroventricularly, or intranasally.

26. 26. The dimer of claim 25, wherein the dimer is administered intravenously.

27. a kit comprising an effective amount of the dimer and a chemotherapeutic agent; where: the kit is for treating a tumor in a subject in need thereof, wherein the dimer is formed by two polypeptide chains, each of the two polypeptide chains comprising an antibody Fc subunit, and the dimer comprises two immunoglobulin single variable domains (ISVDs), one of the ISVDs specific for PD-L1 and another of the ISVDs specific for CTLA4; the PD-L1-specific ISVD comprises a heavy chain variable domain comprising the amino acid sequence set forth in SEQ ID NO:6, and the CTLA4-specific ISVD comprises a heavy chain variable domain comprising the amino acid sequence set forth in SEQ ID NO:20, and for both of the two polypeptide chains: the C-terminus of the PD-L1-specific ISVD is fused to the N-terminus of the CTLA4-specific ISVD via a linker, and the C-terminus of the CTLA4-specific ISVD is fused to the N-terminus of the antibody Fc subunit via a linker; the subject is receiving chemotherapy, chemoradiotherapy, CTL cell therapy, an EGFR tyrosine kinase inhibitor (TKI), and / or an angiogenesis inhibitor; The chemotherapeutic agent comprises a platinum doublet and / or paclitaxel, and the chemotherapeutic agent comprises cisplatin, gemcitabine and / or nab-paclitaxel.

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