Compositions and methods for treating autoimmune diseases and cancer by targeting IGSF8

Abstract

The present invention provides methods and compositions for treating cancer and / or autoimmune diseases by modulating the expression and / or activity of IGSF8 and its binding ligand. Pharmaceutical compositions include, but are not limited to, antibodies that specifically bind to human IGSF8 and have the activity of inhibiting IGSF8-mediated immunosuppression in a subject in need thereof. Pharmaceutical compositions may include, but are not limited to, antibodies that specifically bind to human IGSF8 and have the activity of inhibiting IGSF8-mediated immunosuppression in a subject in need thereof.

Description

[Technical Field]

[0001] This international patent application claims priority to international patent application number PCT / CN2020 / 108129, filed on 10 August 2020, and its entire contents, including all drawings and arrangement, are incorporated herein by reference. [Background technology]

[0002] IGSF8 (Immunoglobulin Superfamily Member 8, also known as EWI-2, CD316, and numerous other aliases) encodes a 613-amino acid (or 65 kDa) protein that is a member of the EWI subfamily of the immunoglobulin protein superfamily. This subfamily includes a transmembrane domain, an EWI (Glu-Trp-Ile) motif (hence the EWI subfamily), and a variable number of immunoglobulin domains.

[0003] The sequences of the human and mouse IGSF8 proteins are 91% identical. While IGSF8 transcripts are expressed in almost all tissues tested in both species, little is known about its biological function. IGSF8 has been reported to specifically and directly interact with the tetraspanins CD81 and CD9, but not with other tetraspanins or integrins, suggesting it may regulate the roles of CD9 and CD81 in specific cellular functions such as cell migration and viral infection (Stipp et al., J. Biol. Chem. 276(44):40545~40554, 2001). Furthermore, IGSF8 has been found to directly interact with the other tetraspanin KAI1 / CD82, a tumor suppressor, thus suggesting its potential as a tumor suppressor. IGSF8 is likely important or necessary for inhibiting KAI1 / CD82-mediated cancer cell migration (Zhang et al., Cancer Res. 63(10):2665~2674, 2003). IGSF8 has also been found to bind to integrin α4β1 from MOLT-4 T leukemia cells, suggesting that IGSF8-dependent rearrangement of the α4β1-CD81 complex on the cell surface is related to IGSF8's effects on integrin-dependent morphology and motility (Kolesnikova et al., Blood 103(8):3013~3019, 2004). Finally, IGSF8 has been found to regulate α3β1 integrin-dependent cellular functions on laminin-5 (Stipp et al., JCB 163(5):1167~1177, 2003).

[0004] For example, checkpoint-based immunotherapy using anti-CTLA-4 antibodies and anti-PD-1 / PD-L1 antibodies has shown significant clinical efficacy in many patients, but the vast majority of cancer patients still do not respond to these therapies. Researchers are trying to understand why such T-cell-based immunotherapies are ineffective for these so-called "non-responders."

[0005] Tumors can evade T cell-mediated immunity by downregulating the expression of major histocompatibility complex class I (MHC-I) molecules. Partial or complete loss of MHC-I expression on the surface of cancer cells has been demonstrated to be a major mechanism of acquired resistance to certain T cell-based immunotherapies. More importantly, approximately 40% of cancer patients who have acquired resistance to anti-PD-1 / PD-L1 or CTLA4 immunotherapy showed complete loss of MHC-I expression on cancer cells. These tumors are "immunologically inert" tumors and unfortunately constitute more than 70% of all tumors in cancer patients.

[0006] MHC-I-deficient tumor cells can, at least theoretically, completely avoid killing by T cells, but the possibility of being destroyed by natural killer (NK) cells of the innate immune system still remains. However, in the tumor microenvironment (TME), for reasons that are not yet fully understood, most NK cells are inactivated and cannot specifically recognize and kill cancer cells that do not express MHC-I.

[0007] On the other hand, certain immunosuppressive receptors (e.g., NKG2A, PD-1, LAG-3, TIGIT, and TIM-3) have been found to be expressed on both effector T / NK cells. Some monoclonal antibodies against these targets can reverse the functional exhaustion of NK cells in tumors, so NK cell-based cancer immunotherapy is expected to complement the limitations of T cell-based immunotherapy. However, almost all of the ligands on cancer cells that have been identified as being able to suppress NK cell activity in the tumor microenvironment are HLA ligands, and since these are extremely diverse between individuals and unrelated individuals, there is doubt whether this strategy can be generally applied to a larger patient population. On the other hand, non-HLA ligands on cancer cells that can suppress NK cell activity in the tumor microenvironment have hardly been identified. Summary of the Invention

[0008] Therefore, in order to advance NK cell-based cancer immunotherapy, there remains a need to identify NK cell-suppressive non-HLA ligands that may be hijacked by cancer cells to avoid NK cell-mediated killing in the tumor microenvironment, as well as reagents that can block NK cell suppression.

[0009] One aspect of the present invention relates to an isolated or recombinant monoclonal antibody or antigen-binding fragment thereof that is specific to IGSF8 (for example, specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody or antigen-binding fragment comprises a heavy chain variable region (VH) including VH CDR1, VH CDR2, and VH CDR3, and a light chain variable region (VL) including VL CDR1, VL CDR2, and VL CDR3, wherein (a1) VH CDR1, VH CDR2, and VH CDR3 each contain, essentially consist of, or consist of the amino acid sequences of SEQ ID NOs. 714, 715, and 716; VL CDR1, VL CDR2, and VL CDR3 each contain, essentially consist of, or consist of the amino acid sequences of SEQ ID NOs. 717, 718, and 719; or (a2) VH CDR1, VH CDR2, and VH CDR3 contains, essentially consists of, or comprises the amino acid sequences of SEQ ID NOs. 754, 755, and 756, respectively; VL CDR1, VL CDR2, and VL CDR3 contain, essentially consist of, or comprise the amino acid sequences of SEQ ID NOs. 757, 758, and 759, respectively; or (b1) VH CDR1, VH CDR2, and VH CDR3 contain, essentially consist of, or comprise the amino acid sequences of SEQ ID NOs. 720, 721, and 722, respectively; VL CDR1, VL CDR2, and VL CDR3 contain, essentially consist of, or comprise the amino acid sequences of SEQ ID NOs. 723, 724, and 725, respectively; or (b2) VH CDR1, VH CDR2, and VH CDR3 contain, essentially consist of, or comprise the amino acid sequences of SEQ ID NOs. 760, 761, and 762, respectively; VL CDR1, VL CDR2, and VL CDR3 contain, essentially consist of, or comprise the amino acid sequences of SEQ ID NOs. 763, 764, and 765, respectively;Or (c) VH CDR1, VH CDR2, and VH CDR3 each contain, consist essentially of, or consist of the amino acid sequence of any one of the VH CDR1, VH CDR2, and VH CDR3 sequences in Tables D and G; VL CDR1, VL CDR2, and VL CDR3 each contain, consist essentially of, or consist of the amino acid sequence of any one of the VL CDR1, VL CDR2, and VL CDR3 sequences in Tables D and G; or (d) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain, consist essentially of, or consist of the amino acid sequence of the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 sequences of any one antibody in Tables D and G, and optionally, the antibody and its antigen-binding fragment do not have the same VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 sequences as the L1 antibody and do not have those sequences of the L2 antibody (e.g., the antibody is not L1 and not L2), providing a monoclonal antibody or its antigen-binding fragment.;

[0010] In certain embodiments, the monoclonal antibody or its antigen-binding fragment comprises (1) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 that each contain the amino acid sequence of the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 sequences of any one antibody in Table D; or (2) VH CDR_{1}, VH CDR_{2}, VH CDR_{3}, VL CDR_{1}, VL CDR_{2}, and VL CDR_{3} that each contain the amino acid sequence of the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 sequences of any one antibody in Table G.

[0011] In some embodiments, a monoclonal antibody or its antigen-binding fragment comprises VH and VL, where (a) VH comprises (i) the amino acid sequence of the corresponding VH FR sequence of any one or more antibodies in Table D (or Table G), (ii) an amino acid sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% sequence identity with the corresponding VH FR sequence of any one or more antibodies in Table D (or Table G); or (iii) VH FR1, VH FR2, VH FR3, and / or VH FR4, which have up to 1, 2, 3, 4, or 5 substitutions, deletions, and / or additions compared to the corresponding VH FR sequence of any one or more antibodies in Table D (or Table G); and / or (b) VL comprises (i) the corresponding VL of the amino acid sequence of any one or more antibodies in Table D (or Table G). (ii) an amino acid sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity with the corresponding VL FR sequence of any one or more antibodies in Table D (or Table G); or (iii) VL FR1, VL FR2, VL FR3, and / or VL FR4 having at most 1, 2, 3, 4, or 5 substitutions, deletions, and / or additions compared to the corresponding VL FR sequence of any one or more antibodies in Table D (or Table G).

[0012] In some embodiments, the monoclonal antibody or its antigen-binding fragment comprises VH and VL, where (a1) VH comprises the amino acid sequences of SEQ ID NOs. 734, 735 and 736, respectively; VL comprises the amino acid sequences of SEQ ID NOs. 737, 738 and 739, respectively; or (a2) VH comprises the amino acid sequences of SEQ ID NOs. 774, 775 and 776, respectively; VL comprises the amino acid sequences of SEQ ID NOs. 777, 778 and 779, respectively; or (b1) VH comprises (b) VH contains the amino acid sequences of SEQ ID NOs. 740, 741, and 742 respectively; VL contains the amino acid sequences of SEQ ID NOs. 743, 744, and 745 respectively; or (b) VH contains the amino acid sequences of SEQ ID NOs. 780, 781, and 782 respectively; VL contains the amino acid sequences of SEQ ID NOs. 783, 784, and 785 respectively; or (c) VH contains the amino acid sequence of a VH sequence from either Table D or Table G; VL contains the amino acid sequence of a VL sequence from either Table D or Table G.

[0013] In some embodiments, the VH and VL sequences include the amino acid sequences of the VH and VL sequences of one antibody from either Table D or Table G, respectively.

[0014] In some embodiments, the monoclonal antibody or its antigen-binding fragment is a human-mouse chimeric antibody, a humanized antibody, a human antibody, a CDR graft antibody, or a resurfaced antibody.

[0015] In some embodiments, the antigen-binding fragment is Fab, Fab', F(ab')2, F d , single-chain Fv or scFv, disulfide-linked F v These include V-NAR domain, IgNar, intrabody, IgGΔCH2, minibody, F(ab')3, tetrabody, triabody, diabody, single-domain antibody, DVD-Ig, Fcab, mAb2, (scFv)2, or scFv-Fc.

[0016] In some embodiments, a monoclonal antibody or its antigen-binding fragment comprises a heavy chain constant region, where (a) the heavy chain constant region is wild-type human IgG1, human IgG2, human IgG3, or human IgG4; or (b) the heavy chain constant region has an Fc domain that is deficient in antibody-dependent cell-mediated cytotoxicity (ADCC), complement-dependent cell-mediated cytotoxicity (CDC), and / or antibody-dependent cell-mediated phagocytosis (ADCP).

[0017] In some embodiments, the heavy chain constant region having a missing Fc domain is IgG1-L234A / L235A (IgG1-LALA), IgG1-L234A / L235A / P329G (IgG1-LALA-PG), IgG1-N297A / Q / G (IgG1-NA), IgG1-L235A / G237A / E318A (IgG1-AAA), IgG1-G236R / L328R (IgG1-RR), IgG1-S298G / T299A (IgG1-GA), IgG1-L234F / L235E / P331S (IgG1- The group is selected from the following: FES), IgG1-L234F / L235E / D265A (IgG1-FEA), IgG4-L234A / L235A (IgG4-LALA), IgG4-S228P / L235E (IgG4-PE), IgG1-E233P / L234V / L235A / G236del / S267K, IgG2-H268Q / V309L / A30S / P331S (IgG2m4), and IgG2-V234A / G237A / P238S / H268A / V309L / A330S / P331S (IgG2c4d).

[0018] In some embodiments, the monoclonal antibody or its antigen-binding fragment has a K content of less than approximately 25 nM, less than 20 nM, less than 15 nM, less than 10 nM, less than 5 nM, less than 2 nM, or less than 1 nM. d It then binds with IGSF8.

[0019] In a particular embodiment, the present invention provides a monoclonal antibody or its antigen-binding fragment that competes with the monoclonal antibody or its antigen-binding fragment with respect to binding to IGSF8.

[0020] Another aspect of the present invention provides a monoclonal antibody or antigen-binding fragment specific to IGSF8, wherein the monoclonal antibody comprises (1) a heavy chain variable region (HCVR) containing an HCVR CDR1-CDR3 sequence which is at least 95% (e.g., 100%) identical to any one of antibody C1-C39, e.g., C30-C39, or which has up to 1, 2, 3, 4, 5, 6, 7, 8, or 9 substitutions therein; and (2) a light chain variable region (LCVR) containing an LCVR CDR1-CDR3 sequence which is at least 95% (e.g., 100%) identical to any one of antibody C1-C39, e.g., C30-C39, or which has up to 1, 2, 3, 4, 5, 6, 7, 8, or 9 substitutions therein.

[0021] Related aspects of the present invention provide a monoclonal antibody or antigen-binding fragment thereof that competes with the monoclonal antibody or antigen-binding fragment thereof with respect to binding to IGSF8.

[0022] In yet another related embodiment, the present invention provides a monoclonal antibody or its antigen-binding site / fragment that specifically binds to the D1 ECD (or Ig-V set domain) of IGSF8 and inhibits binding to KIR3DL1 / 2, for example, to the D2 domain of KIR3DL1 / 2 (e.g., epitopes including S165, I171, and / or M186 of KIR3DL1 / 2).

[0023] Another aspect of the present invention provides a polynucleotide encoding a monoclonal antibody of the present invention, its heavy chain or light chain, or its antigen-binding site / fragment.

[0024] In a related embodiment, the present invention provides a polynucleotide that hybridizes with the polynucleotide or its complement under stringent conditions.

[0025] Another aspect of the present invention provides a vector comprising the polynucleotide of the present invention.

[0026] Another aspect of the present invention provides a host cell comprising a monoclonal antibody encoded by the present invention, its heavy or light chain, or a polynucleotide of the present invention, or a vector of the present invention, for expressing the antibody's antigen-binding site / fragment.

[0027] Another aspect of the present invention provides a method for producing a monoclonal antibody, its heavy or light chain, or its antigen-binding site / fragment, comprising: (i) culturing host cells of the present invention capable of expressing the monoclonal antibody, its heavy or light chain, or its antigen-binding site / fragment, under conditions suitable for expressing the monoclonal antibody, its heavy or light chain, or its antigen-binding site / fragment; and (ii) recovering / isolating / purifying the expressed monoclonal antibody, its heavy or light chain, or its antigen-binding site / fragment.

[0028] Another aspect of the present invention provides a method for modulating an immune response in a subject requiring such modulation, comprising the step of inhibiting the interaction between IGSF8 and a receptor of IGSF8 selected from KIR3DL1, KIR3DL2, and KLRC1 / D2 heterodimers.

[0029] Another aspect of the present invention provides an immunotherapy method for treating cancer in a subject requiring it, comprising the step of inhibiting the interaction between IGSF8 and a receptor of IGSF8 selected from KIR3DL1, KIR3DL2, and KLRC1 / D2 heterodimers.

[0030] Another aspect of the present invention provides a method for treating cancer in a subject requiring such treatment, comprising the step of administering a therapeutically effective dose of an IGSF8 (immunoglobulin superfamily 8) modulator (e.g., an antagonist) to the subject.

[0031] Another aspect of the present invention provides a method for treating cancer in a subject requiring such treatment, comprising the step of administering a therapeutically effective dose of a KIR3DL1 antagonist that inhibits interaction with IGSF8 to the subject.

[0032] Another aspect of the present invention provides a method for treating cancer in a subject requiring such treatment, comprising the step of administering a therapeutically effective dose of a KIR3DL2 antagonist that inhibits interaction with IGSF8 to the subject.

[0033] Another aspect of the present invention provides a method for treating cancer in a subject requiring such treatment, comprising the step of administering a therapeutically effective dose of a KLRC1 / D1 antagonist that inhibits interaction with IGSF8 to the subject.

[0034] Another aspect of the present invention provides the use of an IGSF8 antagonist, a KIR3DL1 antagonist, a KIR3DL2 antagonist, or a KLRC1 / D1 antagonist to inhibit the binding of IGSF8 to a receptor selected from KIR3DL1, KIR3DL2, and KLRC1 / D2 heterodimers for treating cancer in a subject.

[0035] Another aspect of the present invention provides a composition comprising an IGSF8 antagonist, a KIR3DL1 antagonist, a KIR3DL2 antagonist, or a KLRC1 / D1 antagonist for use in any of the claims of the above method, which inhibits the binding of IGSF8 to a receptor selected from KIR3DL1, KIR3DL2, and KLRC1 / D2 heterodimers.

[0036] Another aspect of the present invention provides an antibody that specifically binds to IGSF8 for use in methods of treating cancer, preferably by stimulating the activation of T cells and / or NK cells.

[0037] Another aspect of the present invention provides an antibody that specifically binds to IGSF8 for use in methods of treating cancer, preferably in combination with a second therapeutic agent described herein, such as an immunotherapy agent mediated by a checkpoint inhibitor.

[0038] Another aspect of the present invention provides a device or kit comprising at least one antibody of the present invention, a monoclonal antibody, its heavy chain or light chain, or its antigen-binding site / fragment, and optionally comprising a label for detecting at least one of the antibody, monoclonal antibody, its heavy chain or light chain, or its antigen-binding site / fragment, or a complex comprising at least one of the antibody, monoclonal antibody, its heavy chain or light chain, or its antigen-binding site / fragment.

[0039] Another aspect of the present invention provides a fusion protein comprising an IGSF8 polypeptide and the Fc region of an antibody.

[0040] Another aspect of the present invention provides a polynucleotide encoding the fusion protein of the present invention.

[0041] Another aspect of the present invention provides a vector comprising a polynucleotide encoding the fusion protein of the present invention.

[0042] Another aspect of the present invention provides a host cell comprising a polynucleotide encoding the fusion protein of the present invention, or a vector comprising a polynucleotide encoding the fusion protein of the present invention, for expressing the encoded fusion protein.

[0043] Another aspect of the present invention provides a method for producing a fusion protein of the present invention, comprising the steps of (i) culturing host cells of the present invention capable of expressing the fusion protein under conditions suitable for expressing the fusion protein; and (ii) recovering / isolating / purifying the expressed fusion protein.

[0044] Another aspect of the present invention provides a method for suppressing the activity of primary NK cells or T cells, comprising the step of contacting the primary NK cells or T cells with the fusion protein of the present invention.

[0045] Another aspect of the present invention provides a method for detecting the presence or level of IGSF8 polypeptide in a sample, comprising the step of contacting the IGSF8 polypeptide in the sample with an antibody, monoclonal antibody, or its antigen-binding site / fragment, wherein the antibody, monoclonal antibody, or its antigen-binding site / fragment is labeled with a detectable label or attached to a detectable label.

[0046] Another aspect of the present invention provides a method for monitoring the progression of a disorder associated with abnormal (e.g., higher than normal) IGSF8 expression in a subject, comprising: a) detecting a first level of IGSF8 in a sample obtained from the subject at a first time point using the antibody, monoclonal antibody, or its antigen-binding site / fragment; b) repeating step a) at a subsequent time point to obtain a second level of IGSF8; and c) comparing the first and second levels of IGSF8 detected in steps a) and b), respectively, to monitor the progression of the disorder in the subject, wherein a second level higher than the first level indicates disease progression.

[0047] Another aspect of the present invention provides a method for predicting the clinical outcome of a subject suffering from a disorder associated with abnormal (e.g., higher than normal) IGSF8 expression, comprising: a) determining the level of IGSF8 in a first sample obtained from a subject using the antibody, monoclonal antibody, or antigen-binding site / fragment thereof of the present invention; b) determining the level of IGSF8 in a second sample obtained from a control subject having a superior clinical outcome using the antibody, monoclonal antibody, or antigen-binding site / fragment thereof of the present invention; and c) comparing the levels of IGSF8 in the first and second samples; wherein a significantly higher level of IGSF8 in the first sample compared to the level of IGSF8 in the second sample (e.g., an increase of >20%, >50%, or more) is an indicator that the subject has a worse clinical outcome, and / or a significantly lower level of IGSF8 in the first sample compared to the level of IGSF8 in the second sample (e.g., a decrease of >20%, >50%, or more) is an indicator that the subject has a better clinical outcome.

[0048] Another aspect of the present invention provides a method for evaluating the effectiveness of a therapy for a disorder associated with abnormal (e.g., higher than normal) IGSF8 expression in a subject, comprising: a) determining the level of IGSF8 in a first sample obtained from a subject using the antibody, monoclonal antibody, or its antigen-binding site / fragment, before providing at least a portion of the therapy to the subject; and b) repeating step a) in a second sample obtained from the subject following the provision of the portion of the therapy, wherein a significantly lower level of IGSF8 in the second sample compared to the first sample (>20%, >50%, or greater) is an indicator that the therapy is effective in inhibiting the disorder in the subject; and / or a substantially identical or higher level of IGSF8 in the second sample compared to the first sample is an indicator that the therapy is not effective in inhibiting the disorder in the subject.

[0049] Another aspect of the present invention provides a method for evaluating the effectiveness of a test compound for inhibiting a disorder associated with abnormal (e.g., higher than normal) IGSF8 expression in a subject, comprising the steps of: a) determining the level of IGSF8 in a first sample obtained from a subject using the antibody, monoclonal antibody, or its antigen-binding site / fragment, wherein the first sample is exposed to a certain amount of the test compound; and b) determining the level of IGSF8 in a second sample obtained from a subject using the antibody, monoclonal antibody, or its antigen-binding site / fragment, wherein the second sample has not been exposed to the test compound, wherein a significantly lower level of IGSF8 in the first sample compared to the level in the second sample (>20%, >50%, or greater) is an indicator that the amount of the test compound is effective in inhibiting the disorder in the subject, and / or a substantially identical level of IGSF8 in the first sample compared to the level in the second sample is an indicator that the amount of the test compound is not effective in inhibiting the disorder in the subject.

[0050] Another aspect of the present invention provides a screening method for functional IGSF8 antagonists, comprising the steps of: contacting a candidate drug (e.g., a small molecule, peptide, aptamer, polynucleotide, etc.) with a co-culture of NK cells and target cells expressing IGSF8 and resistant to NK cell-mediated cytotoxicity; and identifying a candidate drug that promotes NK cell-mediated cytolytic activity against the target cells, thereby identifying the candidate drug as an IGSF8 antagonist.

[0051] Another aspect of the present invention provides a screening method for functional IGSF8 antagonists, comprising the step of contacting a candidate drug (e.g., a small molecule, peptide, aptamer, polynucleotide, etc.) with Jurkat NFAT reporter cells in the presence of a T cell activation signal and IGSF8, wherein if the reporter cells are not activated in the absence of the candidate drug but are activated in the presence of the candidate drug, the candidate drug is identified as a functional IGSF8 antagonist.

[0052] Another aspect of the present invention provides an antibody that specifically binds to KIR3DL1 / 2 for use in methods of treating cancer by inhibiting the interaction of KIR3DL1 / 2-IGSF8, thereby stimulating NK cell activation.

[0053] Another aspect of the present invention provides an antibody that specifically binds to KIR3DL1 / 2 for use in methods of treating cancer, preferably in combination with a second therapeutic agent of the invention as described herein, such as an immunotherapy agent mediated by a checkpoint inhibitor.

[0054] Another aspect of the present invention provides a monoclonal antibody or antigen-binding fragment thereof that is specific to KIR3DL1 / 2, preferably to an epitope comprising the second / intermediate / D2 Ig-like domain of the ECD of KIR3DL1 / 2, or residues S165, I171, and / or M186.

[0055] Another aspect of the present invention provides a monoclonal antibody or its antigen-binding fragment that competes with a monoclonal antibody or its antigen-binding fragment in terms of binding to KIR3DL1 / 2.

[0056] Another aspect of the present invention provides a monoclonal antibody or its antigen-binding site / fragment that specifically binds to the intermediate / D2 ECD of KIR3DL1 / 2 (for example, specifically binds to an epitope containing residues S165, I171, and / or M186), thereby inhibiting the binding of IGSF8 to KIR3DL1 / 2.

[0057] Any embodiment of the Invention, including embodiments described solely in the Examples or Claims, may be freely combined with any one or more other additional embodiments of the Invention, unless expressly and explicitly excluded or inappropriate. [Brief explanation of the drawing]

[0058] [Figure 1] This study presents the results of a genome-wide co-culture screening of natural killer (NK) cells and cancer cell lines (colorectal cancer cell line Colo205), demonstrating that loss of IGSF8 function in Colo205 enhances the cytotoxicity of natural killer (NK) cells against Colo205. The IGSF8 gene is one of the top two hits whose loss sensitizes Colo205 cells to NK cell death. [Figure 2A] Figure 2A shows dose-response curves of primary NK cells from human donors 2 and 3 treated with human Fc control or human IGSF8-hFc (human Fc-tagged IGSF8). Compared to the Fc control, NK cell viability significantly decreases as the concentration of IGSF8-hFc increases. [Figure 2B] Figure 2B shows dose-response curves of primary T cells from human donor 2 treated with human Fc (hFc) control or human IGSF8-hFc (human Fc-tagged IGSF8). Compared to the hFc control, T cell viability significantly decreases as the concentration of IGSF8-hFc increases. [Figure 2C] We confirmed a statistically significant (p<0.005) dose-dependent decrease in NK cell viability induced by the IGSF8-Fc fusion protein. [Figure 2D] This shows the top five enriched KEGG pathways in RNA-seq of NK cells treated with IGSF8-hFc fusion protein or hFc control protein. [Figure 2E] This shows the relative mRNA expression of genes in NK cells treated with IGSF8-hFc fusion protein or hFc control protein. [Figure 2F] This study demonstrates the effect of the IGSF8-hFc fusion protein on primary NK cell proliferation. [Figure 2G] This study demonstrates the effect of the IGSF8-hFc fusion protein on the proliferation of primary CD4+ T cells. [Figure 2H] This study demonstrates the effect of the IGSF8-hFc fusion protein on the activation of primary CD4+ T cells. [Figure 3A] Figure 3A shows that CRISPR / Cas9-mediated IGSF8 deletion in B16-F10 melanoma cells significantly reduces the ability of such tumor cells to proliferate in vivo (measured by tumor volume in mm3) in a mouse xenograph model (n=8 mice per group). sgIGSF8-1 and -2 represent two experimental groups in which the IGSF8 gene was deleted in B16-F10 tumor cells using two different CRISPR / Cas9 sgRNAs targeting different regions of IGSF8, before injecting these IGSF8-deleted B16-F10 tumors into mice. As a control, the AAV integration site AAVS1 was similarly deleted in control B16-F10 tumor cells using an AAVS1-specific sgRNA. [Figure 3B] Figure 3B shows that the delayed in vivo tumor growth after IGSF8 deletion is not due to the relative difference in in vitro cell growth rate of B16-F10 melanoma cells lacking the gene. There is no statistically significant difference in in vitro cell proliferation rate between B16-F10 cells lacking IGSF8 and B16-F10 cells lacking AAVS1. [Figure 4]We demonstrated that deletion of IGSF8 in various cancer cell lines via CRISPR / Cas9-mediated gene editing promotes CXCL10 expression, which was measured as a relative expression multiplier increase in CXCL10 compared to the same cancer cells deleting AAVS1. H292 (NCI-H292) is a human mucoepidermal lung cancer cell line, A549 is a human lung cancer cell line, Colo205 is Dukes' type D colorectal adenocarcinoma cell line, N87 is a human gastric cancer cell line, and A375 is a human melanoma cell line. [Figure 5A] This shows the relative enhancement of various gene expression in B16-F10 cells (Figures 5A and 5C) and tumors (Figures 5B and 5D) upon deletion of AAVS1 or IGSF8 by CRISPR / Cas9-mediated gene editing. *: P<0.05; **: P<0.01; ***: P<0.001. [Figure 5B] This shows the relative enhancement of various gene expression in B16-F10 cells (Figures 5A and 5C) and tumors (Figures 5B and 5D) upon deletion of AAVS1 or IGSF8 by CRISPR / Cas9-mediated gene editing. *: P<0.05; **: P<0.01; ***: P<0.001. [Figure 5C] This shows the relative enhancement of various gene expression in B16-F10 cells (Figures 5A and 5C) and tumors (Figures 5B and 5D) upon deletion of AAVS1 or IGSF8 by CRISPR / Cas9-mediated gene editing. *: P<0.05; **: P<0.01; ***: P<0.001. [Figure 5D] This shows the relative enhancement of various gene expression in B16-F10 cells (Figures 5A and 5C) and tumors (Figures 5B and 5D) upon deletion of AAVS1 or IGSF8 by CRISPR / Cas9-mediated gene editing. *: P<0.05; **: P<0.01; ***: P<0.001. [Figure 6A] This shows the gene expression of IGSF8 in human cancer cell lines (date obtained from Broad Institute Cancer Cell Line Encyclopedia (CCLE)). [Figure 6B]The Cancer Genome Atlas (TCGA) cohort shows statistically significant elevated expression of IGSF8 in various tumors. [Figure 6C] This shows the clinical relevance of IGSF8 in the Cancer Genome Atlas (TCGA) cohort. Higher IGSF8 expression is associated with worse related clinical outcomes in different cancer types. [Figure 7] The binding affinity of a representative recombinant anti-IGSF8 antibody of the present invention to the extracellular domain of IGSF8, and its EC50 value as measured by ELISA, are shown. [Figure 8] This document shows a representative antibody-dependent cell-mediated cytotoxicity (ADCC) assay of the anti-IGSF8 antibody of the present invention, using NK cells as effector cells and A431 cancer cells as target cells, along with the associated EC50 values. [Figure 9] This shows a human CXCL10 ELISA assay of Colo205 cells treated with a representative anti-IGSF8 antibody (10 μg / mL) of the present invention. [Figure 10] This study demonstrates the efficacy of the present invention's representative anti-IGSF8 monoclonal antibody against tumor growth in B16 isogenic mice. B16-F10 cells were subcutaneously injected into wild-type (WT) C57BL / 6 mice. Subsequently, the mice were administered 2 mg / kg of anti-IGSF8 antibody or control human IgG1 every 3 days for a total of 4 doses, starting on day 6. Data are shown mean ± SEM (n=8 mice per group). [Figure 11] This line graph shows that there was no significant difference in body weight between groups of experimental mice treated with either anti-IGSF8 antibody or control human IgG1. [Figure 12] This study demonstrates a synergistic effect between the target anti-IGSF8 antibody and anti-PD-1 antibody in reducing the increase in B16-F10 melanoma tumor volume in isogenic mice. [Figure 13A] This shows the effect of the IGSF8-hFc fusion protein on the cytolytic activity of NK cells co-cultured with K562 cells. [Figure 13B]This study demonstrates the effect of the IGSF8-hFc fusion protein on perforin production in NK cells in an NK-K562 co-culture model. [Figure 14] This study shows the effects on the cytolytic activity of NK cells co-cultured with K562 cells, K562 cells overexpressing IGSF8, or IGSF8 knockout K562 cells. The NK cells were derived from two different donors. [Figure 15A] This shows the topological domain of IGSF8. [Figure 15B] This shows the effect of the D1 and D2-4 domains of the IGSF8 protein on the cytolytic activity of NK cells co-cultured with K562 cells. [Figure 16A] This paper outlines a CRISPR screening strategy for de-orphanifying the IGSF8 receptor on NK cells. [Figure 16B] This shows a dot plot of top selected genes from CRISPR screening. [Figure 17A] This shows the core map of the lentiviral vector used to express the KIR receptor. [Figure 17B] This shows the binding of biotin-labeled IGSF8 to different KIR family proteins. [Figure 17C] The core maps of two lentiviral vectors used to express the KLRC1 / D1 heterodimer receptor are shown. [Figure 17D] This demonstrates that only the KLRC1 / D1 heterodimer, and not each monomer individually, binds to the recombinant IGSF8-hFc protein. [Figure 17E] This study demonstrates that the binding of IGSF8 to KIR3D1 / 2 or KLRC1 / D1 receptors is mediated by the D1(Ig-V set) ECD of IGSF8. [Figure 18A] This shows the topological domains of KIR3DL1 / 2, as well as the individual domain constructs used to narrow down the binding domains of KIR3DL1 / 2 to IGSF8. [Figure 18B]This demonstrates the binding of biotin-labeled IGSF8 to different domains of KIR3DL1 / 2. [Figure 19A] This shows the multiple sequence alignment of KIR family proteins and the three residues required for IGSF8 binding. [Figure 19B] The crystal structure of KIR3DL1 and the three residues required for IGSF8 binding are shown. [Figure 20] This demonstrates the binding of biotin-labeled IGSF8 to different mutants of KIR3DL1 / 2. [Figure 21] This shows the binding and EC50 values ​​of IGSF8 monoclonal antibodies (mAbs) B34, 1B4, 2B4, 1C2, 3F12, B46, and B104 to CT26 cells in which human IGSF8 was forcibly expressed on the cell surface. At least a few of these antibodies (e.g., 1B4, B46, and B104) also bind to mouse IGSF8 expressed on CT26 cells (data not shown). [Figure 22] This shows the binding of IGSF8 mAb to the D1 domain of IGSF8 on CT26 cells. [Figure 23A] This figure illustrates two embodiments of an antibody blocking assay. In the left panel, CT26 cells expressing ligand IGSF8 are treated with soluble biotin-labeled receptors (KIR3DL1 / 2) and an anti-IGSF8 mAb, and the bound receptors are then detected with PE-streptavidin. In the right panel, MC38 cells expressing IGSF8 ligand are contacted with KLR- or KIR-receptor-expressing CT26 cells, and an anti-IGSF8 antibody capable of blocking the MC38-CT26 cell / cell conjugate reduces the formation of a FACS-detectable conjugate. [Figure 23B] This demonstrates the blockage of cell-cell conjugate formation between IGSF8-expressing MC38 cells and KIR3DL2-expressing CT26 cells by the selected anti-IGSF8 antibody. [Figure 23C] This study demonstrates the blockage of cell-cell conjugate formation between IGSF8-expressing MC38 cells and KLRC1 / D1 heterodimer-expressing CT26 cells by an anti-IGSF8 antibody. [Figure 24A] Figure 24A is a diagram of the NK cell suppression assay shown in Figure 24B. [Figure 24B] Figure 24B shows that the IGSF8-mediated suppression of K562 cell killing by human primary NK cells can be reversed by anti-IGSF8 mAbs. [Figure 25] Figure 25A shows the in vivo antitumor efficacy using the B16-F10 syngeneic model. Figure 25B shows the response of individual mice treated with anti-IGSF8 mAb or isotype-matched IgG control. [Figure 26] Figure 26A shows the in vivo antitumor efficacy using an LLC syngeneic mouse model. Figure 26B shows the in vivo antitumor efficacy using a CT26 syngeneic mouse model. [Figure 27] This shows the relative mRNA expression of genes in the LLC syngeneic mouse model. [Figure 28] The amino acid sequences of the variable regions of the heavy and light chains of the L1 and L2 antibodies are shown. CDR sequences, following the IMGT numbering scheme, are enclosed in boxes. Underlined sequences include the CDR region and adjacent framework region sequences that may affect binding affinity. [Figure 29] This heatmap shows the negative selection of mutants within the L1 heavy chain CDR. Gray squares represent amino acid substitutions that reduce binding compared to the original sequence of the L1 CDR residue at the same position. Darker gray shading indicates weaker binding compared to the original residue. [Figure 30] This heatmap shows positive selection of mutants within the L1 heavy chain CDR. Gray squares represent amino acid substitutions that enhance / increase binding compared to the original sequence of the L1 CDR residue at the same position. Darker gray shading indicates stronger binding compared to the original residue. [Figure 31] This shows a heatmap of negative selection of mutants within the L1 light chain CDR. [Figure 32] This shows a heatmap of positive selection of mutants within the L1 light chain CDR. [Figure 33] This shows a heatmap of negative selection of mutants within the L2 heavy chain CDR. [Figure 34] This shows a heatmap of positive selection of mutants within the L2 heavy chain CDR. [Figure 35] This shows a heatmap of negative selection of mutants within the L2 light chain CDR. [Figure 36] This shows a heatmap of positive selection of mutants within the L2 light chain CDR. [Figure 37-1] Figures 37A to 37D show the binding affinity of representative L1 and L2 antibodies of the present invention to human (Figure 37A), monkey (Figure 37B), and mouse (Figure 37C) IGSF8 expressed on the surface of CT26 cells, as well as their EC50 values ​​measured by FACS (Figure 37D). [Figure 37-2] Figures 37A to 37D show the binding affinity of representative L1 and L2 antibodies of the present invention to human (Figure 37A), monkey (Figure 37B), and mouse (Figure 37C) IGSF8 expressed on the surface of CT26 cells, as well as their EC50 values ​​measured by FACS (Figure 37D). [Figure 38] Figure 38A shows lentiviral-mediated CRISPR / Cas9-mediated knockdown of KIR3DL2 in NK cells, as measured by FACS. Figure 38B shows that the IGSF8-mediated suppression of K562 cell killing by human primary NK cells can be reversed by the loss of KIR3DL2 on NK cells. [Figure 39] FACS demonstrates that representative L1 and L2 antibodies can completely block the interaction between IGSF8 and KIR3DL2 in a dose-dependent manner. [Figure 40A] Figures 40A-40D show the in vitro antitumor cell efficacy of representative L1 and L2 antibodies in co-culture models of primary NK cells and cancer cell lines Jurkat (Figure 40A), SU-DHL2 (Figure 40B), LNCap (Figure 40C), and K562 (Figure 40D). ****: P<0.0001. [Figure 40B]Figures 40A-40D show the in vitro antitumor cell efficacy of representative L1 and L2 antibodies in co-culture models of primary NK cells and cancer cell lines Jurkat (Figure 40A), SU-DHL2 (Figure 40B), LNCap (Figure 40C), and K562 (Figure 40D). ****: P<0.0001. [Figure 40C] Figures 40A-40D show the in vitro antitumor cell efficacy of representative L1 and L2 antibodies in co-culture models of primary NK cells and cancer cell lines Jurkat (Figure 40A), SU-DHL2 (Figure 40B), LNCap (Figure 40C), and K562 (Figure 40D). ****: P<0.0001. [Figure 40D] Figures 40A-40D show the in vitro antitumor cell efficacy of representative L1 and L2 antibodies in co-culture models of primary NK cells and cancer cell lines Jurkat (Figure 40A), SU-DHL2 (Figure 40B), LNCap (Figure 40C), and K562 (Figure 40D). ****: P<0.0001. [Figure 41] Figures 41A-41B show the in vitro antitumor cell efficacy of representative L1 and L2 antibodies using co-culture models of PBMCs with cancer cell lines H1437 (Figure 41A) and SKBR3 (Figure 41B). ****: P<0.0001. [Figure 42] Figures 42A-42B show the in vitro antitumor cell efficacy of representative L1 and L2 antibodies using co-culture models of PBMCs and cancer cell lines SW480 (Figure 42A) and H520 (Figure 42B). The efficacy of L1 or L2 antibodies containing normal human IgG1 or an IgG1-deficient mutant (IgG1-LALA) was compared. **: P<0.01; ***: P<0.001; ****: P<0.0001. [Figure 43A] Figure 43A shows the in vivo antitumor efficacy of representative L1 antibodies using the B16-F10 syngeneic model. [Figure 43B] Figure 43B shows a comparison between L1 antibodies containing normal human IgG1 and IgG4, and those containing the IgG1-deficient mutant (IgG1-LALA). **: P<0.01; ***: P<0.001; ****: P<0.0001. [Figure 44] This shows the expression of effector NK and T cell marker genes in B16 tumors treated with L1 antibodies containing normal human IgG1, IgG4, and an IgG1-deficient mutant (IgG1-LALA). *: P<0.05 **: P<0.01. [Modes for carrying out the invention]

[0059] 1. Overview The immunoglobulin superfamily member 8 (IGSF8) gene encodes a member of the immunoglobulin protein superfamily, possessing a single transmembrane (TM) domain. IGSF8 contains an extracellular IgV-set domain, which is found in a diverse protein family including T cell receptors such as CD2, CD4, CD80, and CD86, as well as immune checkpoints such as PD1, LAG3, and PDL1. In humans, IGSF8 is thought to be overexpressed in the histological tissues of selected cancer patients compared to control levels in normal human tissues.

[0060] The inventions described herein are based in part on the finding that IGSF8 is a novel cancer therapeutic target and therefore IGSF8 antagonists can be used to treat such cancers. The data presented herein show that IGSF8 is specifically expressed in cancer cells and is highly expressed in several types of cancer, particularly melanoma, cervical cancer, non-small cell lung cancer, colorectal cancer, and many other cancers. IGSF8 interacts with T cells and NK (natural killer) cells, inhibiting NK cell and T cell proliferation and / or reducing NK cell and T cell survival. On the other hand, knocking out the IGSF8 gene or, instead, inactivating the function of IGSF8 improves tumor invasion by T cells and NK cells and enhances cytolytic activity in vivo.

[0061] More specifically, the present invention is partly based on the finding that IGSF8 has a previously unrecognized function as a novel inhibitory ligand for activated NK cells and functions as an immune checkpoint that controls NK cell-mediated immune surveillance for cancer. Recombinant IGSF8 protein suppresses the proliferation and cytolytic activity of activated primary NK cells or T cells. On the other hand, IGSF8 inhibition (by anti-IGSF8 monoclonal antibodies, etc.) has yielded in vivo efficacy in several rodent oncological animal models.

[0062] The invention described herein, which is partially based on the inhibition of IGSF8-mediated NK cell function, is more advantageous than MHC class I (HLA)-based NK cell inhibition, partly because MHC I molecules are highly diverse among unrelated individuals, while IGSF8 is not only non-polymorphic among different individuals but also highly conserved across species (e.g., highly conserved between humans and experimental animals such as mice), allowing anti-IGSF8 agents, including anti-human IGSF8 monoclonal antibodies, to be directly tested in animal (e.g., mouse) models.

[0063] The invention described herein is further based on the finding that cleaved IGSF8 having only the D1 domain as its extracellular domain is sufficient for NK cell suppression, while other cleaved IGSF8 proteins lacking only the D1 domain completely lose their NK cell suppression function, thus enabling IGSF8 to specifically bind to primary NK cells via its D1 domain-Ig V set domain.

[0064] Furthermore, the inventions described herein are based on the finding that IGSF8 binds to NK cells by specifically binding to the KIR family receptor KIR3DL2 (and to a lesser extent KIR3DL1) expressed on the surface of NK cells. Just as tumors can evade T cell-mediated immunity by downregulating MHC-I or inhibiting T cell function by expressing PD-L1 ligands and binding to PD1 on T cells, tumors can similarly evade NK cell-mediated immune surveillance against cancer by upregulating IGSF8 by binding to specific KIR receptors (e.g., KIR3DL1 / 2) for IGSF8 on NK cells.

[0065] The inventions described herein are further based on the finding that IGSF8 binds to NK cells by specifically binding to the KLRC1 / KLRD1 heterodimer receptor (not KLRC1 or KLRD1 monomer alone) expressed on the surface of NK cells. As described above, tumors may upregulate IGSF8 by binding to the IGSF8-specific KLRC1 / D1 heterodimer receptor on NK cells, thereby evading NK cell-mediated immune surveillance of cancer.

[0066] Since IGSF8 is known to be expressed at high levels in multiple types of tumors, immunotherapy using anti-IGSF8 mAbs as checkpoint inhibitors may increase the pool of patients who respond to checkpoint inhibitor treatment. Furthermore, patients with tumors that have acquired resistance to PD-1 therapy may also express IGSF8 as an alternative immune evasion strategy, and IGSF8 blockade may provide an additional avenue for overcoming resistance to PD-1 immunotherapy.

[0067] The inventions described herein are further based on the finding that anti-IGSF8 therapy acts synergistically with anti-PD1 / PD-L1 therapy, partly by activating both T cells and NK cells in the tumor microenvironment, as demonstrated by the animal models described herein.

[0068] Accordingly, the present invention provides a monoclonal antibody that specifically binds to IGSF8 (particularly its Ig V-set extracellular domain) and an antigen-binding fragment thereof. Such an antibody may inhibit one or more functions of IGSF8, such as the binding of IGSF8 to NK cell surface receptors (e.g., KIR3DL1 or KIR3DL2 or KLRC1 / D1), thereby reversing or reducing IGSF8-mediated inhibition of NK cell activity and / or viability. The present invention further provides nucleic acids encoding an anti-IGSF8 antibody or its antigen-binding fragment, vectors having such nucleic acid coding sequences for expression in suitable host cells, and methods for producing such an antibody or its antigen-binding fragment by culturing host cells capable of expressing such an antibody or its antigen-binding fragment. The present invention further provides methods for using such an antibody for diagnostic, prognostic, and therapeutic purposes.

[0069] Several antibodies against IGSF8 have been developed, and most have been validated for binding to or blocking IGSF8, demonstrating enhanced cancer cell killing by ADCC, NK, and / or T cells against cancer cells expressing IGSF8. More importantly, the data presented herein demonstrate that simultaneous inhibition of IGSF8 function and the PD-1 / PD-L1 immune checkpoint produces a synergistic effect in an in vivo mouse model of cancer (melanoma).

[0070] The antibodies described herein are partially characterized by their high binding affinity to IGSF8. The antibodies described herein are further partially based on the surprising discovery that certain formats of antibodies with reduced effector function exhibit superior antitumor efficacy compared to antibodies with full effector function.

[0071] The present invention also provides monoclonal antibodies and their antigen-binding fragments that specifically bind to one of the IGSF8 receptors on NK cells and / or T cells, such as KIR3DL1, KIR3DL2, or KLRC1 / D1, and reverse or reduce the inhibition of NK / T cell activity and / or viability by IGSF8 binding to one or more of these receptors. Antibodies specific to KIR3DL2 or KIR3DL1 may also be specific to the D2 extracellular domain of KIR3DL1 / 2, which is responsible for IGSF8 binding, and include antibodies that specifically block IGSF8 binding to residues S165, I171, and / or M186 of KIR3DL1 / 2. Such antibodies may also inhibit one or more functions of KIR3DL1 / 2 and / or KLRC1 / D1, such as IGSF8 binding, thereby reversing or reducing IGSF8-mediated inhibition of NK cell activity and / or viability. The present invention further provides nucleic acids encoding such antibodies or antigen-binding fragments against KIR3DL1 or KIR3DL2 or KLRC1 / D1, vectors having such nucleic acid coding sequences for expression in suitable host cells, and methods for producing such antibodies or antigen-binding fragments by culturing host cells capable of expressing such antibodies or antigen-binding fragments. The present invention further provides methods for using such antibodies for diagnostic, prognostic, and therapeutic purposes.

[0072] Accordingly, the inventions described herein particularly provide methods and reagents for modulating an immune response or treating cancer by interfering with / antagonizing the interaction of one or more receptors on NK / T cells (e.g., KIR3DL1 or KIR3DL2 or KLRC1 / D1) that modulate (e.g. inhibit) / antagonize IGSF8 activity / IGSF8 function, in any combination with any second therapeutic agent targeting a PD-1 / PD-L1 immune checkpoint.

[0073] Detailed aspects of the present invention are described further individually in the following various sections. However, it should be understood that any one embodiment of the present invention, including embodiments described only in the examples or drawings, and embodiments described only under one of the following sections, can be combined with any other embodiment(s) of the present invention.

[0074] 2.Definition The term "antibody," in its broadest sense, encompasses a variety of antibody structures, including but not limited to monoclonal antibodies, polyclonal antibodies, and multispecific antibodies (e.g., bispecific antibodies). Furthermore, in a broader sense, "antibody" may refer to a molecule that includes heavy chain complementarity-determining regions (CDRs) 1, 2, and 3, and light chain CDRs 1, 2, and 3, and is capable of binding to an antigen. Additionally, "antibody" includes, but is not limited to, chimeric antibodies, humanized antibodies, human antibodies, and antibodies from various species such as mice, humans, and cynomolgus monkeys.

[0075] However, in a narrower sense, "antibody" refers to various monoclonal antibodies, including chimeric monoclonal antibodies, humanized monoclonal antibodies, and human monoclonal antibodies.

[0076] In some embodiments, the antibody comprises a heavy chain variable region (HCVR or VH) and a light chain variable region (LCVR or VL). In some embodiments, the antibody comprises at least one heavy chain (HC) including the heavy chain variable region and at least a portion of the heavy chain constant region, and at least one light chain (LC) including the light chain variable region and at least a portion of the light chain constant region. In some embodiments, the antibody comprises two heavy chains, each heavy chain comprising the heavy chain variable region and at least a portion of the heavy chain constant region, and two light chains, each light chain including the light chain variable region and at least a portion of the light chain constant region.

[0077] Any other antibody used herein that contains a single-chain Fv (scFv) or a polypeptide single-chain containing all six CDRs (three heavy-chain CDRs and three light-chain CDRs) is considered to have heavy and light chains. In some such embodiments, the heavy chain is a region of the antibody containing three heavy-chain CDRs, and the light chain is a region of the antibody containing three light-chain CDRs.

[0078] As used herein, the term “heavy chain variable region (HCVR or VH)” refers to at least the heavy chain CDR1 (CDR-H1 or VH-CDR1), framework 2 (HFR2 or VH-FR2), CDR2 (CDR-H2 or VH-CDR2), FR3 (HFR3 or VH-FR3), and CDR3 (CDR-H3 or VH-CDR3). In some embodiments, the heavy chain variable region also includes at least a portion of FR1 (HFR1 or VH-FR1) which is N-terminus with respect to CDR-H1, and / or at least a portion of FR4 (HFR4 or VH-FR4) which is C-terminus with respect to CDR-H3.

[0079] As used herein, the term “heavy chain constant region” refers to a region containing at least three heavy chain constant domains: CH1, CH2, and CH3. Non-limiting exemplary heavy chain constant regions include γ, δ, and α. Non-limiting exemplary heavy chain constant regions also include ε and μ. Each heavy chain constant region corresponds to an antibody isotype. For example, an antibody containing a γ constant region is an IgG antibody (e.g., IgG1, IgG2, IgG3, IgG4), an antibody containing a δ constant region is an IgD antibody, an antibody containing an α constant region is an IgA antibody, an antibody containing an ε constant region is an IgE antibody, and an antibody containing a μ constant region is an IgM antibody.

[0080] Certain isotypes may be further subdivided into subclasses. For example, IgG antibodies include, but are not limited to, IgG1 (containing the γ1 constant region), IgG2 (containing the γ2 constant region), IgG3 (containing the γ3 constant region), and IgG4 (containing the γ4 constant region) antibodies; IgA antibodies include, but are not limited to, IgAl (containing the α1 constant region) antibodies and IgA2 (containing the α2 constant region) antibodies; and IgM antibodies include, but are not limited to, IgM1 (containing the μ1 constant region) antibodies and IgM2 (containing the μ2 constant region) antibodies.

[0081] The heavy chain constant region contains an Fc (Fragment Crystallizable) domain at the C-terminus of the molecule. The primary function of the Fc region is to induce immunoeffector functions such as antibody-dependent cell-mediated cytotoxicity (ADCC), complement-dependent cell-mediated cytotoxicity (CDC), and antibody-dependent cell-mediated phagocytosis (ADCP) through interaction with cell surface receptors called Fc receptors (FcRs) and several complement system proteins (e.g., C1q). Different antibody isotypes may have different degrees of involvement in immunoeffector function, and Fc manipulation strategies have been employed to enhance or reduce immunoeffector function.

[0082] As used herein, the term "heavy chain" refers to a polypeptide that includes at least a heavy chain variable region and has or does not have a leader sequence. In some embodiments, the heavy chain includes at least a portion of the heavy chain constant region. As used herein, the term "full-length heavy chain" refers to a polypeptide that includes the heavy chain variable region and the heavy chain constant region and has or does not have a leader sequence, and has or does not have a C-terminal lysine.

[0083] As used herein, the term “light chain variable region (LCVR or VL)” refers to a region comprising the light chain CDR1 (CDR-L1 or VL-CDR1), framework (FR)2 (LFR2 or VL-FR2), CDR2 (CDR-L2 or VL-CDR2), FR3 (LFR3 or VL-FR3), and CDR3 (CDR-L3 or VL-CDR3). In some embodiments, the light chain variable region also includes at least a portion of FR1 (LFR1 or VL-FR1) and / or at least a portion of FR4 (LFR4 or VL-FR4).

[0084] As used herein, the term "light chain steady-state region" refers to the light chain steady-state domain C L This refers to the region that includes λ and κ. An unrestricted, exemplary light chain constant region includes λ and κ.

[0085] As used herein, “light chain” refers to a polypeptide that includes at least a light chain variable region and has or does not have a leader sequence. In some embodiments, the light chain includes at least a portion of the light chain constant region. As used herein, the term “full-length light chain” refers to a polypeptide that includes a light chain variable region and a light chain constant region and has or does not have a leader sequence.

[0086] The term (of antibodies) “antibody fragment” or “antigen-binding fragment” includes, but is not limited to, antigen-binding fragments such as Fv, single-stranded Fv(scFv), Fab, Fab', and (Fab')2.

[0087] A "reference antibody that binds to the same epitope" can be determined by an antibody competition assay. This refers to an antibody that blocks 50% or more of the binding of the reference antibody to its antigen in a competition assay, and conversely, a reference antibody blocks 50% or more of the binding of the antibody to its antigen in a competition assay. When used in the context of antibodies competing for the same epitope, the term "competition" means that the competition between antibodies is determined by the assay, in which the antibody being tested prevents or inhibits the specific binding of the reference antibody to the common antigen.

[0088] Numerous types of competitive binding assays, e.g., solid-phase direct or indirect radioimmunoassays (RIAs), solid-phase direct or indirect enzyme immunoassays (EIAs), sandwich competitive assays (e.g., Stahli et al., 1983, Methods in Enzymology 9:242~253); solid-phase direct biotin-avidin EIA (e.g., Kirkland et al., 1986, J.Immunol.137:3614~3619); solid-phase direct labeling assays; solid-phase direct labeling sandwich assays (e.g., see Harlow and Lane, 1988, Antibodies, A Laboratory Manual, Cold Spring Harbor Press); 125 Solid-phase direct-labeled RIAs using labeling (see, e.g., Morel et al., 1988, Molec. Immunol. 25:7-15); solid-phase direct-labeled biotin-avidin EIAs (see, e.g., Chung et al., 1990, Virology 176:546-552); and directly labeled RIAs (Moldenhauer et al., 1990, Scand. J. Immunol.) may be used.

[0089] Typically, such assays involve the use of purified antigen bound to a solid surface or cells having either of these, an unlabeled test antigen-binding protein, and a labeled reference antibody. Competitive inhibition is measured by determining the amount of labeling bound to the solid surface or cells in the presence of the test antibody. Typically, the test antibody is present in excess. Antibodies identified by the competitive assay (competitive antibodies) include antibodies that bind to the same epitope as the reference antibody, and antibodies that bind to an adjacent epitope so closely to the epitope bound by the reference antibody that sterically hindrance occurs. In some embodiments, an excess of competitive antibodies will inhibit the specific binding of the reference antibody to the common antigen by at least 40%, 45%, 50%, 55%, 60%, 65%, 70%, or 75%. In some examples, binding is inhibited by at least 80%, 85%, 90%, 95%, or 97% or more.

[0090] The term "antigen" refers to a molecule or part of a molecule that can be conjugated by an antibody or a selective binder such as an immunologically functional fragment thereof, and that can be used in mammals to produce an antibody capable of binding to that antigen. An antigen may have one or more epitopes that can interact with an antibody.

[0091] The term "epitope" refers to a portion of an antigen molecule that receives a selective binder, such as an antibody or a fragment thereof. The term includes any determinant that can specifically bind to an antibody. Epitopes may be contiguous or discontinuous (for example, in a polypeptide, amino acid residues that are not contiguous within the polypeptide sequence but receive the binding of an antigen-binding protein within the molecular context). In some embodiments, an epitope may be mimicky in that it contains a three-dimensional structure similar to an epitope used to generate an antibody, but contains none or only some of the amino acid residues found in that epitope used to generate the antibody. Epitope determinants may include amino acids, sugar side chains, or chemically active surface groups such as phosphoryl or sulfonyl groups, and may possess specific three-dimensional structural properties and / or specific charge properties.

[0092] In some embodiments, an “epitope” is defined by the method used to determine it. For example, in some embodiments, an antibody binds to the same epitope as a reference antibody if it binds to the same region of the antigen determined by hydrogen-deuterium exchange (HDX).

[0093] In certain embodiments, when binding to the same region of the antigen determined by X-ray crystallography, the antibody binds to the same epitope as the reference antibody.

[0094] As used herein, “chimeric antibody” refers to an antibody comprising at least one variable region derived from a first species (e.g., mouse, rat, cynomolgus monkey, etc.) and at least one constant region derived from a second species (e.g., human, cynomolgus monkey, chicken, etc.). In some embodiments, the chimeric antibody comprises at least one mouse variable region and at least one human constant region. In some embodiments, all variable regions of the chimeric antibody are derived from the first species, and all constant regions of the chimeric antibody are derived from the second species.

[0095] As used herein, “humanized antibody” refers to an antibody in which at least one amino acid in the framework region of a non-human variable region (e.g., mouse, rat, cynomolgus monkey, chicken, etc.) is replaced with a corresponding amino acid derived from a human variable region. In some embodiments, the humanized antibody includes at least one human constant region or a fragment thereof. In some embodiments, the humanized antibody fragment is Fab, scFv, (Fab')2, etc.

[0096] As used herein, "CDR-grafted antibody" refers to a humanized antibody in which one or more complementarity-determining regions (CDRs) of a first species (non-human) are grafted onto a framework region (FR) of a second species (human).

[0097] As used herein, "human antibodies" refers to antibodies produced in humans, antibodies produced in non-human animals possessing human immunoglobulin genes such as XENOMOUSE®, and antibodies selected using in vitro methods such as phage display, where the antibody repertoire is based on human immunoglobulin sequences.

[0098] "Host cell" refers to a cell that may be, or has been, a recipient of a vector or isolated polynucleotide. The host cell may be a prokaryotic or eukaryotic cell. Exemplary eukaryotic cells include mammalian cells such as primate or non-primate animal cells; fungal cells such as yeast; plant cells; and insect cells. Non-exclusive exemplary mammalian cells include, but are not limited to, NSO cells, PER.C6® cells (Crucell), and 293 and CHO cells, as well as their derivatives, such as 293-6E and DG44 cells, respectively.

[0099] As used herein, the term “isolated” refers to a molecule that has been separated from at least some of its components as they are normally found in nature, or from at least some of the components as they are normally produced. For example, a polypeptide is referred to as “isolated” when it has been separated from at least some of the components of the cell in which it was produced. If a polypeptide is secreted from a cell after expression, physically separating the supernatant containing the polypeptide from the cell that produced it is considered to be “isolated” the polypeptide. Similarly, a polynucleotide is referred to as “isolated” if it is not part of a larger polynucleotide as it is normally found in nature (e.g., genomic DNA or mitochondrial DNA in the case of a DNA polynucleotide), or, for example, if it is separated from at least some of the components of the cell in which it was produced, in the case of an RNA polynucleotide. Thus, a DNA polynucleotide contained in a vector within a host cell may be referred to as “isolated” unless the polynucleotide is not found in nature in that vector.

[0100] In this specification, the terms “subject” and “patient” are used interchangeably to refer to mammals such as humans. In some embodiments, methods for treating other non-human mammals, such as, not limited to, rodents, apes, felines, canines, horses, cattle, pigs, sheep, goats, mammalian laboratory animals, mammalian farm animals, mammalian sports animals, and mammalian pets are also provided. In some examples, “subject” or “patient” refers to a (human) subject or patient who requires treatment for a disease or disorder.

[0101] As used herein, the terms “subject” or “patient subject” refer to a substance obtained from or derived from a subject of interest, including cells and / or other molecular entities to be characterized and / or identified based on physical, biochemical, chemical and / or physiological properties. For example, the phrase “disease sample” and its variations refer to any sample obtained from a subject that is expected or known to contain cells and / or molecular entities to be characterized.

[0102] "Tissue or cell sample" means an aggregate of cells similar to those obtained from the tissue of the subject or patient. Sources of tissue or cell samples may be solid tissues such as fresh, frozen, and / or preserved organ or tissue samples or biopsies or aspirates; blood or any blood component; bodily fluids such as sputum, cerebrospinal fluid, amniotic fluid, peritoneal fluid, or interstitial fluid; or cells from any stage in the subject's pregnancy or onset. Tissue samples may also be primary cells or cultured cells or cell lines. Optionally, tissue or cell samples may be obtained from diseased tissue / organs. Tissue samples may contain compounds that do not naturally coexist with tissue, such as preservatives, anticoagulants, buffers, fixatives, nutrients, or antibiotics.

[0103] As used herein, “reference sample,” “reference cell,” or “reference tissue” refers to a sample, cell, or tissue obtained from a source known or believed to be free from the disease or condition for which the methods or compositions of the present invention are particularly used. In one embodiment, the reference sample, reference cell, or reference tissue is obtained from a healthy part of the body of the same subject or patient for whom the disease or condition is to be identified using the compositions or methods of the present invention. In one embodiment, the reference sample, reference cell, or reference tissue is obtained from a healthy part of the body of at least one individual who is not the subject or patient for whom the disease or condition is to be identified using the compositions or methods of the present invention. In some embodiments, the reference sample, reference cell, or reference tissue is obtained previously from a patient before the onset of the disease or condition, or at an earlier stage of the disease or condition.

[0104] "Disorder" or "disease" is any condition that would benefit from treatment with one or more of the IGSF8 antagonists of the present invention. This includes chronic and acute disorders or diseases, including those pathological conditions that predispose mammals to the disorder in question. Non-limiting examples of disorders to be treated herein include cancer.

[0105] In this specification, the term “cancer” is used to refer to a group of cells that exhibit abnormally high levels of proliferation and growth. Cancer may be benign (also called a benign tumor), premalignant, or malignant. Cancer cells may be solid cancer cells (i.e., those that form a solid tumor) or leukemia cancer cells. In this specification, the term “cancer growth” refers to proliferation or growth by cancer-containing cells that result in a corresponding increase in the size or extent of the cancer. "Chemotherapy agents" are compounds that may be useful in the treatment of cancer. Examples of chemotherapy agents include alkylating agents such as thiotepa and CYTOXAN® cyclophosphamide, alkyl sulfonates such as busulfan, improsulfan, and biposulfan, aziridines such as benzodopa, carbocon, methuadopa, and uredopa, ethyleneimines and methylmelamines such as altoretamine, triethylenemelamine, triethylenephosphoramide, triethylenethiophosphoramide, and trimethylolmelamine, acetogenins (especially bratacin and bratacinone), camptothecin (including its synthetic analog topotecan), bryostatin, calistatin, CC-1065 (including its synthetic analogs adzeresin, karzeresin, and bizeresin), and cryptophycin (especially cryptophycin 1 and cryptophycin 1). Toficin 8), dorastatin, duocalmycin (including synthetic analogs KW-2189 and CB1-TM1), eleuterobin, pancratistatin, sarcodicin, spongstatin, chlorambucil, chlornafadin, colophosphamide, estramustine, ifosfamide, mechloretamine, mechloretamine oxide hydrochloride, melphalan, nobenbitin, fenesterine, prednimustine, trophosphamide, nitrogen mustards such as uracil mustard, carmustine, chlorozotocin, fotemustine, lomustine, nimustine, and ranimustine, nitrosolairs such as enediin antibiotics (e.g., calicheamicin, especially calicheamine gamol and calicheamine omegamol (e.g., Agnew, Chem (See Intl. Ed. Engl, 33.183~186 (1994)), dynemicin including dynemicin A, bisphosphonates such as clodronate, esperamicin, and neocardinostatin chromophores and related chromoprotein enediin antibiotic chromophores), acrasinomycin, actinomycin, outramycin, azaserin, bleomycin, kacchinomycin, carabicin, carminomycin, cardinophilin, chromomycin, dactinomycin, daunorubicin, detorubicin, 6-diazo-5-oxo-L-norleucine, ADRIAMYCIN® doxorubicin (morpholino-doxorubicin,(including cyanomorpholino-doxorubicin, 2-pyrrolino-doxorubicin, and deoxydoxorubicin), epirubicin, esorubicin, idarubicin, marcelomycin, mitomycin, e.g., mitomycin C, mycophenolic acid, nogaramycin, olibomycin, peplomycin, potophyllomycin, puromycin, keramycin, rhodorubicin, streptonigrin, streptozocin, tubercidine, ubenimec Antimetabolites such as dinostatin, zolubicin, methotrexate and 5-fluorouracil (5-FU), folate analogs such as denopterin, methotrexate, pteropterin, and trimethrexate, purine analogs such as fludarabine, 6-mercaptopurine, thiamiprine, and thioguanine, ancitabine, azacitidine, 6-azauridine, carmofur, cytarabine, dideoxyuridine, doxifluridine, enocitabine, flox gourd Pyrimidine analogs such as din, androgens such as callussterone, dromostanone propionate, epithiostanol, mepitiostane, and testactone, anti-adrenaline such as aminoglutethimide, mitotane, and trilostane, folic acid supplements such as floric acid, acegraton, aldofamide glycoside, aminolevulinic acid, enyluracil, amsacrin; Bestrabusil, Bisanthren, edatraxate, defofamine, demecolsin, Diadicone, erhomitin, eriptinium acetate, epotilon, etoglucide, gallium nitrate, hydroxyurea, lentinan, ronidynin, meitansinoids such as meitansin and anthamitosin, mitoglucon, mitoxantrone, mopidammole, nitraerine, pentostatin, fenamet, pirarubicin, losoxantrone, podophyllic acid, 2-ethylhydrazide, procarbazine, PSK (registered trademark) polysaccharide (JHS Natural Products, Eugene, OR), Lazoxane, Rhizoxin, Schizophyllan, Spirogermanium, Tenuazonic Acid, Triadicone, 2,2',2"-Trichlorotriethylamine. Trichothecenes (especially T-2 toxin, Beraclin A, Loridine A and Angidin), Urethane, Vindesine, Dacarbazine, Mannomustine, Mitobronitol, Mitractol, Pipobroman. Gacitosine, Arabinoside ("Ara-C"),Cyclophosphamide, thiotepa, taxoids, for example, TAXOL® paclitaxel (Bristol-Myers Squibb Oncology, Princeton, NJ), ABRAXANE® cremohol-free albumin-engineered nanoparticle formulation of paclitaxel (American Pharmaceutical Partners, Schaumberg, Illinois), and TAXOTERE® doxetaxel (Rhone-Poulenc Platinum analogs such as Rorer, Antony, France), chlorambucil, GEMZAR® gemcitabine, 6-thioguanine, mercaptopurine, methotrexate, cisplatin, oxaliplatin, and carboplatin, vinblastine, platinum, etoposide (VP-16), ifosfamide, mitoxantrone, vincristine, NAVELBINE® vinorelbine, novantrone, teniposide, edatrexate, daunomycin, aminopterin, Xeloda, ibandronate, irinotecan (Camptosar, CPT-11) (iri Examples of pharmaceutically acceptable treatments include, but are not limited to, notecan and 5-FU and leucovorin treatment regimens, the topoisomerase inhibitor RFS2000, difluoromethylornithine (DMFO), retinoids such as retinoic acid, capecitabine, combretastatin, leucovorin (LV), oxaliplatin including oxaliplatin treatment regimens (FOLFOX), inhibitors of PKC-α, Raf, H-Ras, EGFR (e.g., erlotinib (TARCEVA®)) and VEGF-A that reduce cell proliferation, as well as any pharmaceutically acceptable salts, acids, or derivatives of any of the above.

[0106] Further non-limiting exemplary chemotherapeutic agents include anti-hormone agents that modulate or inhibit the hormonal effects on cancer, such as anti-estrogen agents and selective estrogen receptor modulators (SERMs), such as tamoxifen (including NOLVADEX® tamoxifen), raloxifen, droloxifen, 4-hydroxytamoxifen, trioxyfen, keoxyfen, LY117018, onapristone, and FARESTON® toremifene; aromatase inhibitors that inhibit aromatase, an enzyme that regulates estrogen production in the adrenal gland, such as 4(5)-imidazole, aminoglutethimide, MEGASE® megestrol acetate, AROMASIN® exemestane, formestany, fadrozol, RIVISOR® borozole, FEMARA® letrozole, and ARIMIDESEX® anastozole. Examples include rhozols and antiandrogens, such as flutamide, nilutamide, bicalutamide, leuprolide, and goserelin, as well as troxacitabine (1,3-dioxolane nucleoside cytosine analog), antisense oligonucleotides, in particular those that inhibit the expression of genes in signaling pathways involved in abnormal cell proliferation, such as PKC-α, Ralf, and H-Ras, ribozymes such as VEGF expression inhibitors (e.g., ANGIOZYME® ribozymes), and HER2 expression inhibitors, gene therapy vaccines, such as ALLOVECTIN® vaccine, LEUVECTIN® vaccine, and VAXID® vaccine, PROLEUKIN® rIL-2, LURTOTECAN® topoisomerase 1 inhibitor, ABARELIX® rmRH, and any pharmaceutically acceptable salts, acids, or derivatives of any of the above.

[0107] "Anti-angiogenic agents" or "angiogenic inhibitors" refer to low molecular weight substances, polynucleotides (e.g., including inhibitory RNA (RNAi or siRNA)), polypeptides, isolated proteins, recombinant proteins, antibodies, or their conjugates or fusion proteins that directly or indirectly inhibit angiogenesis, vascular formation, or undesirable vascular permeability. It should be understood that anti-angiogenic agents include agents that bind to and block the angiogenic vitality of angiogenic factors or their receptors. For example, anti-angiogenic agents include antibodies or other antagonists against angiogenic agents, such as antibodies against VEGF-A (e.g., bevacizumab (AVASTIN®)) or antibodies against VEGF-A receptors (e.g., KDR receptor or Flt-1 receptor), anti-PDGFR inhibitors such as GLEEVEC® (imatinib mesylate), and small molecules that block VEGF receptor signaling (e.g., PTK787 / ZK2284, SU6668, SUTENT® / SU1248 (sunitinib malate), AMG706, or those described, for example, in international patent application, international publication 2004 / 113304). Anti-angiogenic agents also include native angiogenesis inhibitors, such as angiostatins and endostatins. For example, see Klagsbrun and D'Amore (1991) Annu. Rev. Physiol. 53:217~39; Streit and Detmar (2003) Oncogene 22:3172~3179 (e.g., Table 3, which describes anti-angiogenic therapies in malignant melanoma); Ferrara & Alitalo (1999) Nature Medicine 5(12):1359~1364; Tonini et al. (2003) Oncogene 22:6549~6556 (e.g., Table 2, which describes known anti-angiogenic factors); and Sato (2003) Int. J. Clin. Oncol. 8:200~206 (e.g., Table 1, which describes angiogenic agents used in clinical trials).

[0108] As used herein, “proliferation inhibitor” refers to a compound or composition that inhibits the proliferation of cells (e.g., cells expressing VEGF) in vitro or in vivo. Therefore, examples of proliferation inhibitors may include those that significantly reduce the proportion of S-phase cells (e.g., cells expressing VEGF). Examples of proliferation inhibitors include, but are not limited to, agents that block cell cycle progression (at a point other than the S phase), such as agents that induce G1 arrest and M-phase arrest. Classical M-phase blockers include vincus (vincristine and vinblastine), taxanes, and topoisomerase II inhibitors such as doxorubicin, epirubicin, daunorubicin, etoposide, and bleomycin. These G1-stopping agents have also been used to induce S-phase arrest, such as DNA alkylating agents such as tamoxifen, prednisone, dacarbazine, mechloretamine, cisplatin, methotrexate, 5-fluorouracil, and ara-C. Further information can be found, for example, on page 13 of "The Molecular Basis of Cancer," Chapter 1, Title "Cell cycle regulation, oncogenees, and antineoplastic drugs," edited by Mendelsohn and Israel, by Murakami et al. (WBSaunders, Philadelphia, 1995). Taxanes (paclitaxel and docetaxel) are both anticancer drugs derived from the yew tree. Docetaxel (TAXOTERE®, Rhone-Poulenc Rorer) is derived from the European yew tree and is a semi-synthetic analog of paclitaxel (TAXOL®, Bristol-Myers Squibb). Paclitaxel and docetaxel promote the assembly of microtubules from tubulin dimers, preventing depolymerization and stabilizing microtubules, thereby inhibiting mitosis in cells.

[0109] The term "antineoplastic composition" refers to a composition useful for the treatment of cancer, comprising at least one active therapeutic agent. Examples of therapeutic agents include, for example, chemotherapeutic agents, proliferation inhibitors, cytotoxic agents, drugs used in radiotherapy, anti-angiogenic agents, cancer immunotherapeutic agents (also called immuno-oncological agents), apoptotic agents, antitubulin agents, and other agents for treating cancer, such as anti-HER-2 antibodies, anti-CD20 antibodies, epidermal growth factor receptor (EGFR) antagonists (e.g., tyrosine kinase inhibitors), HER1 / EGFR inhibitors (e.g., erlotinib (TARCEVA®)), platelet-derived growth factor inhibitors (e.g., GLEEVEC® (imatinib mesylate)), COX2 inhibitors (e.g., celecoxib), interferons, and CTLA4 inhibitors (e.g., anti-CTLA antibodies). Examples of the present invention include, but are not limited to, pyrimumab (YERVOY®), PD-1 inhibitors (e.g., anti-PDl antibody, BMS-936558), PDL1 inhibitors (e.g., anti-PDL1 antibody, MPDL3280A), PDL2 inhibitors (e.g., anti-PDL2 antibody), VISTA inhibitors (e.g., anti-VISTA antibody), cytokines, antagonists (e.g., neutralizing antibodies) that bind to one or more of the following targets: ErbB2, ErbB3, ErbB4, PDGFR-β, BlyS, APRIL, BCMA, PD-1, PDL1, PDL2, CTLA4, VISTA, or VEGF receptors, TRAIL / Apo2, and other bioactive and organic chemical agents. Combinations thereof are also included in the present invention.

[0110] "Treatment" refers to therapeutic treatment, where, for example, the objective is to delay (reduce) a targeted condition or disability, and the objective is to prevent the recurrence of a condition or disability. "Treatment" encompasses any administration or application of a therapeutic agent for a disease (also referred herein as "disability" or "condition") in mammals, including humans, and includes inhibiting or delaying the disease or its progression, preventing its onset, partially or completely alleviating the disease, partially or completely alleviating one or more symptoms of the disease, or restoring or repairing a lost, missing or defective function, or stimulating an inefficient process. The term "treatment" also includes reducing the severity of any phenotypic trait and / or reducing the incidence, degree, or likelihood of that trait. Persons requiring treatment include those who already have a disability, those at risk of a recurrence of the disability, or those for whom a recurrence of the disability should be prevented or slowed.

[0111] The term “effective dose” or “therapeutic effective dose” refers to the amount of drug that is effective in treating a disease or disorder in a subject. In some embodiments, the effective dose refers to the dose and duration required to obtain the desired therapeutic or preventive outcome. The therapeutic effective dose of the IGSF8 antagonist of the present invention may vary depending on factors such as the individual’s medical condition, age, sex, and weight, and the antagonist’s ability to elicit the desired response in the individual. The therapeutic effective dose encompasses the amount in which any debilitating or adverse effects of the IGSF8 antagonist outweigh any therapeutically beneficial effects.

[0112] The "prophylactically effective dose" refers to the amount that is effective in the dose and duration necessary to achieve the desired prophylactic outcome. While not always the case, generally, the prophylactically effective dose will be less than the therapeutically effective dose, as prophylactic doses are used for pre-disease or early-stage disease.

[0113] A "pharmaceutically acceptable carrier" refers to a non-toxic solid, semi-solid, or liquid filler, diluent, encapsulating material, formulation adjuvant, or carrier commonly used in the art for use with a therapeutic agent that together constitutes a "pharmaceutical composition" for administration to a subject. A pharmaceutically acceptable carrier is non-toxic to the recipient at the dose and concentration used and is compatible with the other components of the formulation. A pharmaceutically acceptable carrier is appropriate for the formulation in which it is used. For example, if the therapeutic agent is administered orally, the carrier may be a gel capsule. If the therapeutic agent is administered subcutaneously, the carrier is ideally non-irritating to the skin and does not cause injection site reactions.

[0114] "Product" is any product (e.g., package or container) or kit comprising at least one reagent, for example, a pharmaceutical for the treatment of a disease or disorder, or a probe for the specific detection of a biomarker described herein. In some embodiments, the product or kit is advertised, distributed or sold as a unit for carrying out the method described herein.

[0115] 3. Methods of treating cancer The inventions described herein provide modulators, e.g., antagonists, for IGSF8 (e.g., isolated or recombinant monoclonal antibodies or antigen-binding fragments specific to IGSF8) and its receptors (e.g., KIR3DL1 / 2, KLRC1 / D1) for use in methods of treating human and other non-human mammals, e.g., animal models of cancer.

[0116] In one embodiment, the present invention provides a method for modulating an immune response in a subject requiring such modification, comprising the step of inhibiting the interaction between IGSF8 and a receptor of IGSF8 selected from KIR3DL1, KIR3DL2, and KLRC1 / D2 heterodimers. In a particular embodiment, the method comprises the step of administering an anti-IGSF8 monoclonal antibody of the present invention or an antigen-binding fragment thereof (such as those described herein) to the subject.

[0117] In other embodiments, the present invention provides an immunotherapy method for treating cancer in a subject requiring such treatment, comprising the step of inhibiting the interaction between IGSF8 and a receptor of IGSF8 selected from KIR3DL1, KIR3DL2, and KLRC1 / D2 heterodimers. In certain embodiments, the method comprises the step of administering an anti-IGSF8 monoclonal antibody of the present invention or an antigen-binding fragment thereof (such as those described herein) to the subject.

[0118] In yet another embodiment, the present invention provides a method for treating or preventing cancer in a subject requiring such treatment, comprising the step of administering to a subject requiring such treatment a therapeutically effective amount of a modulator of IGSF8, KIR3DL1 / 2, or KLRC1 / D1 of the present invention (e.g., an antagonist such as an antibody or its antigen-binding portion / fragment).

[0119] Specifically, the present invention provides a method for treating cancer in a subject requiring such treatment, comprising the step of administering a therapeutically effective dose of an IGSF8 (immunoglobulin superfamily 8) modulator (e.g., an antagonist) to the subject.

[0120] The present invention also provides a method for treating cancer in a subject requiring such treatment, comprising the step of administering a therapeutically effective dose of a KIR3DL1 antagonist that inhibits interaction with IGSF8 to the subject.

[0121] The present invention further provides a method for treating cancer in a subject requiring such treatment, comprising the step of administering a therapeutically effective dose of a KIR3DL2 antagonist that inhibits interaction with IGSF8 to the subject.

[0122] The present invention further provides a method for treating cancer in a subject requiring such treatment, comprising the step of administering a therapeutically effective dose of a KLRC1 / D1 antagonist that inhibits interaction with IGSF8 to the subject.

[0123] In some embodiments, a method for treating cancer is provided, comprising the step of administering an effective amount of the IGSF8, KIR3DL1 / 2, or KLRC1 / D1 modulator of the present invention (e.g., an antagonist, e.g., an antibody or antigen-binding moiety / fragment) to a subject having cancer requiring treatment.

[0124] In some embodiments, the use of an effective amount of the present invention's IGSF8, KIR3DL1 / 2, or KLRC1 / D1 modulator (e.g., an antagonist such as an antibody or its antigen-binding moiety / fragment) for treating cancer is provided.

[0125] Non-limiting exemplary cancers that can be treated with an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) are provided herein and include carcinomas, lymphomas, germ blastomas, sarcomas, and leukemias. More specific non-limiting examples of such cancers include melanoma, cervical cancer, squamous cell carcinoma, small cell lung cancer, pituitary cancer, esophageal cancer, astrocytoma, soft tissue sarcoma, non-small cell lung cancer, adenocarcinoma of the lung, squamous cell carcinoma of the lung, peritoneal cancer, hepatocellular carcinoma, gastrointestinal cancer, pancreatic cancer, glioblastoma, ovarian cancer, liver cancer, bladder cancer, hepatocellular carcinoma, breast cancer, colon cancer, colorectal cancer, endometrial cancer or uterine cancer, salivary gland cancer, kidney cancer, liver cancer, prostate cancer, vulvar cancer, thyroid cancer, liver cancer, brain cancer, endometrial cancer, testicular cancer, bile duct cancer, gallbladder cancer, gastric cancer, melanoma, and various head and neck cancers.

[0126] In certain embodiments, cancers treatable by the method of the present invention using the IGSF8, KIR3DL1 / 2, or KLRC1 / D1 modulator of the present invention (e.g., an antagonist such as an antibody or antigen-binding moiety / fragment) include, but are not limited to, carcinomas, lymphomas, blastomas, sarcomas, and leukemias. More specific, non-limiting examples of such cancers include squamous cell carcinoma, small cell lung cancer, pituitary cancer, esophageal cancer, astrocytoma, soft tissue sarcoma, non-small cell lung cancer, adenocarcinoma of the lung, squamous cell carcinoma of the lung, peritoneal cancer, hepatocellular carcinoma, gastrointestinal cancer, pancreatic cancer, glioblastoma, cervical cancer, ovarian cancer, liver cancer, bladder cancer, hepatocellular carcinoma, breast cancer, colon cancer, colorectal cancer, endometrial or uterine cancer, salivary gland cancer, kidney cancer, liver cancer, prostate cancer, vulvar cancer, thyroid cancer, liver cancer, brain cancer, endometrial cancer, testicular cancer, cholangiocarcinoma, gallbladder cancer, gastric cancer, melanoma, and various head and neck cancers.

[0127] Additional treatable cancers include melanoma (including cutaneous melanoma of the skin), cervical cancer, lung cancer (e.g., non-small cell lung cancer, lung adenocarcinoma, lung squamous cell carcinoma), colorectal cancer, lymphoma (including B-cell lymphoma and DLBCL), leukemia (including CLL and acute myeloid leukemia (AML)), BLCA tumors, breast cancer, head and neck carcinoma, head and neck squamous cell carcinoma, PRAD, THCA, or UCEC, thyroid cancer, urinary tract cancer, uterine cancer, esophageal cancer, liver cancer, or ganglion cancer, kidney cancer, pancreatic cancer, pancreatic ductal carcinoma, ovarian cancer, prostate cancer, glioma, glioblastoma, neuroblastoma, thymoma, B-CLL, and cancers infiltrated by immune cells expressing receptors for IGSF8.

[0128] In certain embodiments, treatable cancers include lung cancer, kidney cancer, pancreatic cancer, colorectal cancer, acute myeloid leukemia (AML), head and neck carcinoma, liver cancer, ovarian cancer, prostate cancer, or uterine cancer.

[0129] In some embodiments, lung cancer is non-small cell lung cancer or squamous cell carcinoma of the lung.

[0130] In some embodiments, the leukemia is acute myeloid leukemia (AML) or chronic lymphocytic leukemia (CLL).

[0131] In some embodiments, breast cancer is invasive breast cancer.

[0132] In some embodiments, ovarian cancer is ovarian serous cystadenomatous carcinoma.

[0133] In some embodiments, the kidney cancer is a clear cell carcinoma of the kidney.

[0134] In some embodiments, colon cancer is colorectal adenocarcinoma.

[0135] In some embodiments, bladder cancer is urothelial carcinoma of the bladder.

[0136] In some embodiments, cancer cells and / or tumor immune-infiltrating cells in the subject express IGSF8.

[0137] While we do not wish to be bound by any particular theory, the method of the present invention relates to NK cells and / or (CD8 + The present invention may be based on at least partially mitigating IGSF8-mediated inhibition of the host innate / adaptive immune system, which is exerted on effector cells of the host innate / adaptive immune system, such as T cells. Such inhibition may be brought about by association with one or more IGSF8 receptors (e.g., KIR3DL1 / 2 and KLRC1 / D1) upon IGSF8 binding, and such inhibition can be at least partially mitigated by inhibiting IGSF8 binding to these receptors expressed on effectors of the host innate / adaptive immune system (e.g., NK cells or T cells). Therefore, the present invention may not rely on (but not necessarily exclude) conventional ADCC- or CDC-mediated killing of target cells by innate immune cells (e.g., NK cells) based on antibodies on the surface of these target cells overexpressing one of the IGSF8 receptors (KIR3DL1 / 2 and KLRC1 / D1, etc.).

[0138] Therefore, in some embodiments, cancer can be treated by inhibiting the binding of IGSF8 to at least one of its receptors, such as KIR3DL1 / 2 and KLRC1 / D1. In some embodiments, cancer expresses IGSF8. See, for example, any cancer described in Figure 6A, Figure 6B, or Figure 6C that exhibits IGSF8 expression.

[0139] In some embodiments, cancer is not characterized by the expression or overexpression of KIR3DL1 / 2. In some embodiments, cancer is characterized by Sézary syndrome, CD30 + It is not cutaneous lymphoma, or cutaneous T-cell lymphoma such as transformed mycosis fungoides.

[0140] In some embodiments, cancer is not characterized by the expression or overexpression of KLRC1 / D1.

[0141] In some embodiments, the KIR3DL1 antagonist is selected from an anti-KIR3DL1 antibody or its antigen-binding moiety / fragment, an inhibitory peptide of KIR3DL1, a nucleic acid that targets KIR3DL1 (RNAi reagents such as aptamers, antisense polynucleotides, siRNA, miRNA, shRNA; guide RNA for type 2 CRISPR / Cas effector enzymes), or a small molecule that targets KIR3DL1 (e.g., molecular weight <1000 Da or <500 Da); if necessary, the KIR3DL1 antagonist is an anti-KIR3DL1 antibody or its antigen-binding moiety / fragment.

[0142] In some embodiments, the KIR3DL2 antagonist is selected from an anti-KIR3DL2 antibody or its antigen-binding moiety / fragment, an inhibitory peptide of KIR3DL2, a nucleic acid that targets KIR3DL2 (RNAi reagents such as aptamers, antisense polynucleotides, siRNA, miRNA, shRNA, etc.; guide RNA for type 2 CRISPR / Cas effector enzymes), or a small molecule that targets KIR3DL2 (e.g., molecular weight <1000 Da or <500 Da); if necessary, the KIR3DL2 antagonist is an anti-KIR3DL2 antibody or its antigen-binding moiety / fragment.

[0143] In some embodiments, an anti-KIR3DL1 / 2 antibody or its antigen-binding moiety / fragment, an inhibitory peptide against KIR3DL1 / 2, a nucleic acid targeting KIR3DL1 / 2, or a small molecule targeting KIR3DL1 / 2 binds to an epitope of KIR3DL1 / 2 containing residues S165, I171, and / or M186, thereby inhibiting IGSF8 binding to the D2 domain of KIR3DL1 / 2.

[0144] In some embodiments, the anti-KIR3DL1 / 2 antibody or its antigen-binding moiety / fragment specifically binds to the intermediate / D2 Ig-like domain of the ECD of KIR3DL1 / 2, and, if necessary, specifically binds to an epitope containing residues S165, I171, and / or M186.

[0145] In some embodiments, the KLRC1 / D1 antagonist is selected from an anti-KLRC1 / D1 antibody or its antigen-binding moiety / fragment, an inhibitory peptide of KLRC1 / D1, a nucleic acid that targets KLRC1 / D1 (RNAi reagents such as aptamers, antisense polynucleotides, siRNA, miRNA, shRNA, etc.; guide RNA for type 2 CRISPR / Cas effector enzymes), or a small molecule that targets KLRC1 / D1 (e.g., molecular weight <1000 Da or <500 Da); if necessary, the KLRC1 / D1 antagonist is an anti-KLRC1 / D1 antibody or its antigen-binding moiety / fragment.

[0146] In some embodiments, the IGSF8 antagonist is selected from an anti-IGSF8 antibody or its antigen-binding moiety / fragment, an inhibitory peptide of IGSF8, a nucleic acid that targets IGSF8 (RNAi reagents such as aptamers, antisense polynucleotides, siRNA, miRNA, shRNA, etc.; guide RNA for type 2 CRISPR / Cas effector enzymes), or a small molecule that targets IGSF8 (e.g., molecular weight <1000 Da or <500 Da); if necessary, the IGSF8 antagonist is an anti-IGSF8 antibody or its antigen-binding moiety / fragment.

[0147] In some embodiments, the IGSF8 antagonist is selected from an anti-IGSF8 antibody or its antigen-binding fragment. In some embodiments, the antibody is a chimeric antibody, a humanized antibody, or a human antibody. In some embodiments, the anti-IGSF8 antibody or its antigen-binding fragment binds to the terminal Ig-V set ECD or D1 of IGSF8. In some embodiments, the anti-IGSF8 antibody or its antigen-binding fragment inhibits the binding of IGSF8 to an epitope containing the intermediate / D2 domain of KIR3DL1 / 2, e.g., KIR3DL1 and / or KIR3DL2, e.g., residues S165, I171, and / or M186 of KIR3DL1 / 2.

[0148] In some embodiments, the antigen-binding moiety / fragment is Fab, Fab', F(ab')2, Fd One-chain Fv or scFv, disulfide-linked F v , V-NAR domain, IgNar, intrabody, IgGΔCH2, minibody, F(ab’)3, tetrabody, tribody, diabody, single-domain antibody, DVD-Ig, Fcab, mAb2, (scFv)2 or scFv-FC.

[0149] In some embodiments, the anti-IGSF8 antibody or an antigen-binding portion / fragment thereof is any one of the monoclonal antibodies described herein, or an antigen-binding portion / fragment thereof (see the section on IGSF8 antagonists, e.g., anti-IGSF8 antibodies).

[0150] In some embodiments, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody of the present invention or an antigen-binding fragment thereof) promotes the expression, secretion of cytokines or target genes selected from the group consisting of CXCL10, CXCL9, TNFα, CD8b, CD8a, Prf1, IFNγ, Gzma, Gzmb, CD274, PDCD1, PDCD1 Ig2, LAG3, Havcr2, Tigit, or CTLA4, or increases the activity in other ways.

[0151] In some embodiments, the increase in the expression, secretion, or other activity of the cytokine or the target gene occurs within the tumor microenvironment.

[0152] In some embodiments, the increase in the expression, secretion, or other activity of the cytokine or the target gene is due to the infiltration of immune cells (e.g., T lymphocytes or NK cells) into the tumor microenvironment.

[0153] In some embodiments, the anti-IGSF8 and / or anti-KIR3DL1 / 2 and / or anti-KLRC1 / D1 antibody or an antigen-binding portion / fragment thereof is conjugated to a cytotoxic agent. The cytotoxic agent can be selected from the group consisting of chemotherapeutic agents, biological agents, toxins, and radioisotopes.

[0154] In some embodiments, the IGSF8 antagonist, KIR3DL1 antagonist, KIR3DL2 antagonist, or KLRC1 / D1 antagonist is an immunostimulatory molecule.

[0155] In some embodiments, IGSF8 antagonists (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention), KIR3DL1 antagonists, KIR3DL2 antagonists, or KLRC1 / D1 antagonists stimulate the activation of T cells or NK cells and / or their invasion into the tumor microenvironment.

[0156] In some embodiments, anti-IGSF8 and / or anti-KIR3DL1 / 2 and / or anti-KLRC1 / D1 antibodies or their antigen-binding moieties / fragments reduce the number of cancerous proliferating cells and / or decrease the volume or size of cancerous tumors.

[0157] In some embodiments, anti-IGSF8 and / or anti-KIR3DL1 / 2 and / or anti-KLRC1 / D1 antibodies or their antigen-binding moieties / fragments are administered in a pharmaceutically acceptable formulation.

[0158] In some embodiments, an anti-IGSF8 antibody or its antigen-binding fragment (e.g., F(ab')2 fragment) is administered together with a second therapeutic agent (see the section on combination therapies incorporated herein by reference).

[0159] In some embodiments, an anti-IGSF8, anti-KIR3DL1 / 2, or anti-KLRC1 / D1 antibody or its antigen-binding fragment is administered together with a second immune checkpoint inhibitor, such as an immune checkpoint inhibitor that restores or enhances T cell-mediated immunotherapy.

[0160] In some embodiments, the immune checkpoint inhibitor is an antibody or antigen-binding fragment specific to PD-1, PD-L1, PD-L2, LAG3, TIGIT, TIM3, NKG2A, CD276, VTCN1, VISR, or HHLA2.

[0161] In some embodiments, an anti-IGSF8, anti-KIR3DL1 / 2, or anti-KLRC1 / D1 antibody or its antigen-binding fragment is administered together with an anti-PD-1 antibody or its antigen-binding fragment, an anti-PD-L1 antibody or its antigen-binding fragment, and / or an anti-CTLA-4 antibody or its antigen-binding fragment. In some embodiments, the anti-IGSF8 antibody is a human antibody.

[0162] In some embodiments, the immune checkpoint inhibitor is an anti-PD-1 antibody such as cemiprimab, nivolumab, or pembrolizumab.

[0163] In some embodiments, the immune checkpoint inhibitor is an anti-PD-L1 antibody such as avelumab, durvalumab, atezolizumab, KN035, or CK-301.

[0164] In some embodiments, the immune checkpoint inhibitor is a PD-1 / PD-L1 (non-antibody) peptide inhibitor such as AUNP12; a PD-L1 small molecule inhibitor such as CA-170; or a macrocyclic peptide such as BMS-986189.

[0165] In certain embodiments, the combination therapy further comprises therapeutic antibodies effective in treating cancer or immunological conditions. Exemplary therapeutic antibodies include: 3F8, 8H9, avagovomab, absiximab, abituzumab, abrazekimab, abrilumab, actokisumab, adalimumab, adecatumumab, aducanumab, afasebicumab, aferimomab, aracizumab pegol, alemtuzumab, alirocumab, artumomab penteate, amatsuximab, amivantamab, anatumomab mafenatox, andecaliximab, anetumablubutansine, aniflorumab, anlukinzumab, apolizumab, and apluzumab. Ixadotin, Alcitumomab, Ascrimbakumab, Aselizumab, Atezolizumab, Atidolutoxumab, Atinumab, Atrolimumab, Avelumab, Adintuxizumab Vedotin, Bapineozumab, Basiliximab, Bavituximab, BCD-100, Vectumomab, Begeromab, Verantamab Mahodotin, Belimumab, Bemarituzumab, Benralizumab, Perlimatoxumab, Permekimab, Persanlimab, Pertilimumab, Besilezomab, Bevacizumab, Bezlotoxumab, Bisilomab, Bimaglumab, Bimekiz Mab, vilutamimab, vivacuzumab, preserumab, blinatumomab, brontubetomab, brosozumab, vococizumab, brazicumab, brentuximab vedotin, briakinumab, brodalumab, brolucizumab, bronticutuzumab, brosumab, kabilizumab, camidanrumab tesirin, camrelizumab, canakinumab, cantuzumab meltansine, cantuzumab brabutansine, caplacizumab, capromab, carrumab, carotuximab, catumakisomab, cBR-doxorubicin immunoconjugate, sedeli Zumab, semiprimab, cergutuzumab amnaleukin, certolizumab pegol, cetrerimab, cetuximab, sibisatamab, silimutuzumab, sitatuzumab bogatox, ixutumumab, crazakizumab, clenoliximab, cribatuzumab tetraxetan, codlituzumab, cofetuzumab peridotin, coltuximab labutancin, conatumumab, concizumab, cosflobiximab, crenezumab, chryzanlizumab, clotedumab, CR6261, kusatuzumab, dasetuzumab, dacrizumab, dalotuzumab,Dapirolizumab pegol, daratumumab, dectrecumab, demcizumab, denintuzumab mahodotin, denosumab, depatuxizumab mahodotin, delrotuximab biotin, detumomab, dezamizumab, dinutuximab, ziridabumab, domaglozumab, dorulimomab aritox, dostalurimab, dorodizumab, DS-8201, durigotuzumab, dupilumab, durvalumab, dusigituzumab, duvortuxizumab, eclomeximab, eculizumab, edovacomab, edrecolomab, efalizumab, efangumab, erderumab, erezza Numab, ergemzumab, elotuzumab, elcilimomab, emuctuzumab, emapalmab, emibetuzumab, emicizumab, enapotamab vedotin, enabatuzumab, enfortumab vedotin, enrimomab pegol, enobrituzumab, enokizumab, enoticumab, encituximab, epitumomab citucetan, epratuzumab, eptinezumab, erenumab, erulizumab, erzumab, etalacizumab, etigirimab, etorilizumab, evinacumab, evolocumab, exvivirumab, fanolesomab, falalimomab, falisimab Faretuzumab, Facinumab, FBTA05, Felbizumab, Fezakinumab, Fivatuzumab, Ficlatuzumab, Figitumumab, Filibumab, Flambotumab, Fletituzumab, Flotetuzumab, Fontrizumab, Foralumab, Folavirumab, Fremanezumab, Fresolimmab, Flobosimab, Flunebetomab, Fluranumab, Futuximab, Galcanezumab, Galiximab, Gancotamab, Ganituzumab, Gantenerumab, Gatipotuzumab, Gabirimomab, Gezibumab, Gemtuzumab Ozogamicin, Gevokizumab, Zilbetomab, Zim Silumab, dilentuximab, glenbatumumab vedotin, golimumab, gomiliximab, goslanemab, guselkumab, lanalumab, ibalizumab, IBI308, ibritumomab tiuxetan, iclucumab, idarucizumab, ifabotuzumab, igobomab, iradatuzumab vedotin, IMAB363, imarumab, imaprelimab, imusilomab, imugatuzumab, incrumab, indatuximab tansine, indusatuzumab vedotin, inebilizumab, infliximab, intetumumab, inorimomab, inotuzumab ozogamicin,Ipilimumab, Iomab-B, Iratumumab, Isatuximab, Iscarimab, Istilatumab, Itorizumab, Ixekizumab, Keriximab, Labetuzumab, Lacunotuzumab, Radilatuzumab Vedotin, Lamparizumab, Lanadermab, Landgrozumab, Laprituximab Emtansine, Larcabiximab, Lebrikizumab, Remaresomab, Rendarizumab, Lembervimab, Renzirumab, Rerdelimumab, Leronlimab, Resofabumab, Retrizumab, Lesatumumab, Ribivirumab, Rifastuzumab Vedotin, Rigerizumab, Ronca Sutuximab tesirin, rosatuxizumab vedotin, rilotomab satetraxetan, lintuzumab, lirirumab, rodelcizumab, lokivetomab, rorbotuzumab meltansine, lucatumumab, rulizumab pegol, lumiliximab, lumuretuzumab, lupalzumab, lupalzumab amadotin, lutikizumab, mapatumumab, marjetuximab, malstacimab, masurimomab, mapurilimumab, matsuzumab, mepolizumab, metemumab, milatuzumab, minretumomab, mirikizumab, milbetuximab sorabtansine, mitumomab, modotuximab Mogamulizumab, Monalizumab, Morolimmab, Mosnetuzumab, Motabizumab, Moxetumomab Pasdotox, Muromonab-CD3, Nacolomabutafenatox, Namilumab, Naptumomab Estafenatox, Naratuximab Emtansine, Narunatumab, Natalizumab, Navixixizumab, Navibumab, Naxitamab, Nevacumab, Necitumumab, Nemolizumab, NEOD001, Nerelimomab, Nesbacumab, Netakimab, Nimotuzumab, Nirsevimab, Nivolumab, Nofetumomab Merpentan, Ovirtoxakimab, Obinutuzumab , okalatuzumab, ocrelizumab, odurimomab, ofatumumab, oraratumamab, olecumub, orendalizumab, orokizumab, omalizumab, ombrutamab, OMS721, onartuzumab, ontuxizumab, onbachirimab, opicinumab, oporutuzumab monatox, olegobomab, orticumab, oterixizumab, ochirimab, otrelutuzumab, oxerumab, ozanezumab, ozoralizumab, padibaximab, palivizumab, pamrebrumab, panitumumab, pancomab, panobacumab, pulsatuzumab, pascolizumab,Pasotuxizumab, Pateclizumab, Patrizumab, PDR001, Pembrolizumab, Pemtumomab, Perakizumab, Partzumab, Paxerizumab, Pidilizumab, Pinatuzumab Vedotin, Pintumomab, Prakurumab, Prezalumab, Prozarizumab, Pogalizumab, Polatuzumab Vedotin, Ponezumab, Polgabiximab, Placinezumab, Prezarizumab, Priliximab, Pritoxaximab, Pritumumab, PRO140, Kirizumab, Lacosumomab, Radrezumab, Rafibirumab, Lalpancizumab, Ramucirumab, Lanebetomab Ranibizumab, Laxibakumab, Labagalimab, Laburizumab, Refanezumab, Legavirumab, REGN-EB, Relatrimab, Remtolumab, Reslizumab, Rilotumumab, Linucumab, Risankizumab, Rituximab, Ribabazumab Pegol, Lobatumumab, Rmab, Lorezumab, Romirukimab, Romosozumab, Rontalizumab, Rosumantuzumab, Robalpituzumab Tecilin, Roberizumab, Rozanolixizumab, Luprizumab, SA237, Sacituzumab Govitecan, Samalizumab, Samlotamab Vedotin, Sarilumab, Satralizumab, Sa Tumomab pendetide, secukinumab, sericrelumab, ceribantumab, cetoxaximab, cetorusumab, sevilumab, cibrotuzumab, SGN-CD19A, SHP647, cifalimumab, siltuximab, simtuzumab, ciprizumab, siltratumab vedotin, silutuzumab, sofituzumab vedotin, solanezumab, solitomab, sonepcizumab, sontuzumab, spartalizumab, stamulumab, thresomab, subutabumab, stimulimab, subizumab, subbratoxumab, tabarumab, takatuzumab tetraxetan, tadocizumab, tarako Tuzumab, talizumab, tarketamab, tamtvetomab, tanezumab, tapritumomab paptox, tarextumab, tavolimab, tecristamab, tefivazumab, terimomab aritox, terisotuzumab, terisotuzumab vedotin, tenatumomab, teneriximab, teprizumab, tepositamab, teprotumumab, tesidorumab, teturomab, tezeperumab, TGN1412, tibrizumab, tildrakizumab, tigatuzumab, timigutuzumab, thymorumab, tilagorumab, tilagotumab, tislerizumab, tisotumab vedotin, TNX-650,Tocilizumab, tomzotuximab, tralizumab, tosatoxumab, tositumomab, tobetumab, tralokinumab, trastuzumab, trastuzumab duocalmazine, trastuzumab emtansine, TRBS07, tregalizumab, tremelimumab, trevoglumab, tucotsuzumab cermoloukin, tubilumab, ubrituximab, urocuplumab, urerumab, urtoxazumab, ustekinumab, utomirumab, vadasutuximab taririn, banarimab, bundutuzumab vedotin, bunchikutuzumab, banusiz Mab, bapariximab, valisakumab, valrirumab, baterizumab, vedolizumab, beltuzumab, bepalimomab, besenkumab, vizilizumab, bovalilizumab, borosiximab, bonrelorizumab, voplaterimab, borsetuzumab mahodotin, botumumab, bunakizumab, xentuzumab, XMAB-5574, zaltumumab, zanolimmab, zatuximab, xenoctuzumab, diralimumab, zolbetuximab (=IMAB362, claudicimab), zolimomab aritox, or combinations thereof.

[0166] In certain embodiments, the second therapeutic agent comprises an antibody or its antigen-binding moiety / fragment that is effective in inducing ADCC, ADCP, and / or CDC.

[0167] In some embodiments, IGSF8 antagonists for treating cancer may be non-antibody proteins, such as soluble versions of the IGSF8 protein or a portion thereof (e.g., Ig-V set ECD) that inhibit the interaction between IGSF8 and its ligand, and may further include a fusion partner as needed, in the form of a fusion molecule such as an (IgG1)Fc fusion. Various exemplary IGSF8 antagonists are described in more detail in the following sections.

[0168] In some embodiments, the KIR3DL1 / 2 antagonist for treating cancer may be a soluble version of the KIR3DL1 / 2 protein or a portion thereof (e.g., the second Ig domain of ECD) that inhibits the interaction between a non-antibody protein, such as IGSF8, and may further include a fusion partner as needed, in the form of a fusion molecule such as an (IgG1)Fc fusion.

[0169] In some embodiments, the KLRC1 / D1 antagonist for treating cancer may be a soluble version of the KLRC1 / D1 protein or a portion thereof (e.g., ECD) that inhibits the interaction between a non-antibody protein, such as IGSF8, and KLRC1 / D1, and may further include a fusion partner as needed, in the form of a fusion molecule such as an (IgG1)Fc fusion.

[0170] The inventions described herein also provide KIR3DL1 / 2 or KLRC1 / D1 antagonists for use in methods of treating humans and other non-human mammals.

[0171] In some embodiments, a method is provided for treating or preventing cancer, comprising the step of administering an effective amount of a KIR3DL1 / 2 or KLRC1 / D1 antagonist to a subject in need of such treatment.

[0172] In some embodiments, methods are provided for activating NK cells, for example, for activating NK cell-mediated immunotherapy (which may be useful for treating or preventing cancer), the methods comprising the steps of contacting NK cells with a KIR3DL1 / 2 or KLRC1 / D1 antagonist, or administering an effective amount of a KIR3DL1 / 2 or KLRC1 / D1 antagonist to a subject in need of such NK cell-mediated immunotherapy.

[0173] In some embodiments, a method for treating cancer is provided, comprising the step of administering a KIR3DL1 / 2 or KLRC1 / D1 antagonist to a subject having cancer.

[0174] In some embodiments, the use of KIR3DL1 / 2 or KLRC1 / D1 antagonists for treating cancer is provided.

[0175] In some embodiments, cancer can be treated by inhibiting the binding between IGSF8 and KIR3DL1 / 2 and / or KLRC1 / D1. In some embodiments, cancer expresses IGSF8. In some embodiments, cancer is not characterized by the expression or overexpression of KIR3DL1 / 2. In some embodiments, cancer is characterized by Sézary syndrome, CD30 + It is not cutaneous lymphoma, nor is it a cutaneous T-cell lymphoma such as transformed mycosis fungoides.

[0176] In some embodiments, the KIR3DL1 / 2 or KLRC1 / D1 antagonist is an anti-KIR3DL1 / 2 or anti-KLRC1 / D1 antibody, or an antigen-binding fragment thereof. In one embodiment, the KIR3DL1 / 2 or KLRC1 / D1 antagonist is an antibody, or an antibody-binding fragment thereof, that specifically binds to KIR3DL1 / 2 or KLRC1 / D1 and inhibits IGSF8 binding to KIR3DL1 / 2 or KLRC1 / D1 (for example, inhibiting KIR3DL1 / 2-mediated IFNγ secretion in NK cells by at least about 20%, 40%, 50%, 60%, 80%, 90% or more). In one embodiment, the anti-KIR3DL1 / 2 or anti-KLRC1 / D1 antibody is a human antibody.

[0177] In certain embodiments, the anti-KIR3DL1 / 2 antibody or its antigen-binding fragment specifically binds to the D2 domain of KIR3DL1 / 2 and inhibits IGSF8 binding. In certain embodiments, the anti-KIR3DL1 / 2 antibody or its antigen-binding fragment specifically binds to an epitope within the D2 domain of KIR3DL1 / 2 and inhibits IGSF8 binding to residues S165, I171, and / or M186 of KIR3DL1 / 2. In one embodiment, the anti-KIR3DL2 antibody is not IPH4102.

[0178] In one embodiment, the KIR3DL1 / 2 antagonist is the extracellular domain (ECD) of IGSF8 that inhibits the binding of IGSF8 to KIR3DL1 / 2, for example, to residues S165, I171 and / or M186 of KIR3DL1 / 2, without causing the inhibitory function of KIR3DL1 / 2 on the activation, proliferation, and / or viability of NK cells.

[0179] In one embodiment, a KIR3DL1 / 2 or KLRC1 / D1 antagonist is a small molecule that binds to KIR3DL1 / 2 or KLRC1 / D1 and inhibits the binding of IGSF8 to KIR3DL1 / 2 or KLRC1 / D1, for example, to residues S165, I171, and / or M186 of KIR3DL1 / 2, without causing the inhibitory function of KIR3DL1 / 2 on NK cell activation, proliferation, and / or viability.

[0180] In one embodiment, the KIR3DL1 / 2 antagonist is a CpG-oligodeoxynucleotide (CpG-ODN), which, upon binding to the first (or D1) Ig-like domain of the ECD of KIR3DL1 / 2, induces downregulation of KIR3DL1 / 2 from the cell surface and translocation to endosomes, thereby delivering the CpG-ODN to the Toll-like receptor 9 and activating NK cells.

[0181] In a related aspect, the present invention provides the use of IGSF8 antagonists, KIR3DL1 antagonists, KIR3DL2 antagonists, or KLRC1 / D1 antagonists that inhibit the binding of IGSF8 to receptors selected from KIR3DL1, KIR3DL2, and KLRC1 / D2 heterodimers for the treatment of cancer in a subject.

[0182] In certain embodiments, use is for combination use with any one or more of the second therapeutic agents described herein.

[0183] Related aspects of the present invention provide compositions for use in any of the methods of the present invention described herein, comprising an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment), a KIR3DL1 antagonist, a KIR3DL2 antagonist, or a KLRC1 / D1 antagonist, which inhibit the binding of IGSF8 to a receptor selected from KIR3DL1, KIR3DL2, and KLRC1 / D2 heterodimers.

[0184] 4. Route of administration and carrier In various embodiments, IGSF8 antagonists (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or KIR3DL1 / 2 antagonists and / or KLRC1 / D1 antagonists can be administered subcutaneously or intravenously.

[0185] In some embodiments, IGSF8 antagonists (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or KIR3DL1 / 2 antagonists and / or KLRC1 / D1 antagonists can be administered in vivo by various routes, including, but are not limited to, oral, intra-arterial, parenteral, intranasal, intramuscular, intracardiac, intraventricular, intratracheal, buccal, rectal, intraperitoneal, inhalation, intradermal, topical, percutaneous, and intrathecal, or by other means, such as by transplantation.

[0186] The composition in question can be formulated in solid, semi-solid, liquid, or gaseous form, and includes, but is not limited to, tablets, capsules, powders, granules, ointments, solutions, suppositories, enemas, injections, inhalants, and aerosols.

[0187] In some embodiments, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist are delivered using gene therapy. As a non-limiting example, nucleic acid molecules encoding the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 (e.g., Cas9 and sgRNA, or Cas12a and crRNA) may be coated onto gold microparticles and delivered intradermally by a particle impact device or "gene gun," for example, as described in the literature (see, e.g., Tang et al., Nature 356:152-154 (1992)).

[0188] In various embodiments, compositions comprising an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist are provided in the form of formulations with various pharmaceutically acceptable carriers (see, for example, Gennaro, Remington: The Science and Practice of Pharmacy with Facts and Comparisons: Drugfacts Plus, 20th edition (2003); Ansel et al., Pharmaceutical Dosage Forms and Drug Delivery Systems, 7th edition, Lippencott Williams and Wilkins (2004); Kibbe et al., Handbook of Pharmaceutical Excipients, 3rd edition, Pharmaceutical Press (2000)). Various pharmaceutically acceptable carriers, including vehicles, adjuvants, and diluents, are available. Furthermore, various pharmaceutically acceptable auxiliary substances such as pH adjusters, buffers, tension adjusters, stabilizers, and wetting agents are also available. Non-limiting exemplary carriers include physiological saline, buffered physiological saline, glucose, water, glycerol, ethanol, and combinations thereof.

[0189] In various embodiments, compositions comprising an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody of the present invention or its antigen-binding fragment) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist may be formulated for injection, such as subcutaneous administration, by dissolving, suspending, or emulsifying it in an aqueous or non-aqueous solvent, such as a vegetable oil or other oil, synthetic fatty acid glycerides, esters of higher fatty acids, or propylene glycol, along with conventional additives as needed, such as solubilizers, isotonic agents, suspending agents, emulsifiers, stabilizers, and preservatives.

[0190] In various embodiments, the composition may be formulated for inhalation using pressurized spray agents such as dichlorodifluoromethane, propane, and nitrogen.

[0191] The compositions can also be formulated in sustained-release microcapsules using biodegradable or non-biodegradable polymers in various embodiments. A non-regular, exemplary biodegradable formulation includes a polylactic acid-glycolic acid (PLGA) polymer. A non-limiting, exemplary non-biodegradable formulation includes a polyglycerin fatty acid ester. Specific methods for producing such formulations are described, for example, in EP1125584A1.

[0192] Also provided are pharmaceutical dosing packs comprising one or more containers containing one or more doses of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody of the present invention or its antigen-binding fragment) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist. In some embodiments, a unit dose is provided, which contains a predetermined amount of a composition comprising an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody of the present invention or its antigen-binding fragment) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, with or without one or more additional agents. In some embodiments, such a unit dose is supplied in a single-use pre-filled syringe for injection. In various embodiments, the composition contained in the unit dose may be formulated with physiological saline or a buffer such as sucrose or phosphate and / or within a stable and effective pH range. Alternatively, in some embodiments, the composition may be provided as a lyophilized powder that can be reconstituted by adding a suitable liquid, such as sterile water. In some embodiments, the composition comprises one or more substances that inhibit protein aggregation, including but not limited to sucrose and arginine. In some embodiments, the composition of the present invention comprises heparin and / or proteoglycans.

[0193] A pharmaceutical composition is administered in an effective dose for the treatment or prevention of a specific indication. The therapeutically effective dose typically depends on the weight of the person being treated, their physical or health condition, the severity of the condition being treated, or the age of the person being treated.

[0194] In some embodiments, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist may be administered in a dose range of about 50 μg / kg body weight to about 50 mg / kg body weight. In some embodiments, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist may be administered in a dose range of about 100 μg / kg body weight to about 50 mg / kg body weight. In some embodiments, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody of the present invention or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist may be administered in a dose range of about 100 μg / kg body weight to about 20 mg / kg body weight. In some embodiments, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody of the present invention or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist may be administered in a dose range of about 0.5 mg / kg body weight to about 20 mg / kg body weight.

[0195] In some embodiments, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody of the present invention or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist may be administered in a dose range of about 10 mg to about 1,000 mg. In some embodiments, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody of the present invention or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist may be administered in a dose range of about 20 mg to about 500 mg. In some embodiments, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody of the present invention or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist may be administered in a dose range of about 20 mg to about 300 mg. In some embodiments, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist may be administered in a dose range of about 20 mg to about 200 mg. IGSF8 antagonists (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or KIR3DL1 / 2 antagonists and / or KLRC1 / D1 antagonist compositions may be administered to the subject as needed. In some embodiments, an effective amount of the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or KIR3DL1 / 2 antagonist and / or KLRC1 / D1 antagonist is administered to the subject once or more times. In various embodiments, an effective amount of the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or KIR3DL1 / 2 antagonist and / or KLRC1 / D1 antagonist is administered to the subject once a month, less than once a month, for example, once every two months, once every three months, or once every six months. In other embodiments, an effective dose of the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist is administered more than once a month, for example, once every two weeks, once a week, twice a week, three times a week, once a day, or multiple times a day. An effective dose of the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist is administered to the subject at least once. In some embodiments, an effective dose of the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist may be administered multiple times over a period of at least one month, at least six months, or at least one year. In some embodiments, an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist are administered to the subject as needed to alleviate one or more symptoms of the condition.

[0196] 5. Combination therapy The IGSF8 antagonists of the present invention (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or KIR3DL1 / 2 antagonists and / or KLRC1 / D1 antagonists comprise any antibody and its functional fragments, which may be administered to subjects in need in combination with other biologically active substances or other treatment procedures for the treatment of a disease. For example, the IGSF8 antagonists (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or KIR3DL1 / 2 antagonists and / or KLRC1 / D1 antagonists may be administered alone or in conjunction with other treatment methods. They may be provided before, substantially simultaneously with, or after other treatment methods, such as radiotherapy.

[0197] In some embodiments, the method of the present invention may include the step of administering to a target an effective amount of a second therapeutic agent, including an immunotherapy agent, an immune checkpoint inhibitor, a cancer vaccine, a chimeric antigen receptor, a chemotherapeutic agent, a radiotherapy agent, an anti-angiogenic agent, a growth inhibitor, an immuno-oncological agent, an antineoplastic composition, a surgical procedure, or a combination thereof.

[0198] To treat cancer, IGSF8 antagonists (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or KIR3DL1 / 2 antagonists and / or KLRC1 / D1 antagonists may be administered in combination with one or more anticancer agents, such as immune checkpoint inhibitors, chemotherapeutic agents, proliferation inhibitors, anti-angiogenic agents, or antineoplastic compositions.

[0199] In some embodiments, the immune checkpoint inhibitor is an antibody or antigen-binding fragment specific to PD-1, PD-L1, PD-L2, LAG3, TIGIT, TIM3, NKG2A, CD276, VTCN1, VISR, or HHLA2.

[0200] In some embodiments, the immune checkpoint inhibitor is an anti-PD-1 antibody, such as cemiprimab, nivolumab, or pembrolizumab.

[0201] In some embodiments, the immune checkpoint inhibitor is an anti-PD-L1 antibody, such as avelumab, durvalumab, atezolizumab, KN035, or CK-301.

[0202] In some embodiments, the immune checkpoint inhibitor is a PD-1 / PD-L1 (non-antibody) peptide inhibitor, e.g., AUNP12; a PD-L1 small molecule inhibitor, e.g., CA-170; or a macrocyclic peptide, e.g., BMS-986189.

[0203] In certain embodiments, an IGSF8 antagonist that specifically binds to IGSF8 (e.g., an anti-IGSF8 monoclonal antibody or its antigen-binding fragment) ("IGSF8-binding antagonist"), e.g., an IGSF8 antagonist or its antigen-binding fragment, is administered together with a second immune checkpoint inhibitor (e.g., an inhibitor of the PD-1 or PD-L1 pathway) to subjects with diseases in which stimulation of the immune system is beneficial, e.g., cancer or infectious diseases. The two antagonists can be administered simultaneously or sequentially, for example, in combination with an IGSF8 antagonist and an immuno-oncology agent, as described below. For the treatment of cancer or infectious diseases, one or more further therapeutic agents, e.g., checkpoint modulators, may be added to treatment with an IGSF8-binding antagonist. In some embodiments, the IGSF8 antagonist is an antibody or its antigen-binding fragment that specifically binds to the D1 (Ig-V set domain) of IGSF8.

[0204] In certain embodiments, a KIR3DL1 / 2 antagonist specifically binds to KIR3DL1 / 2 ("KIR3DL1 / 2-binding antagonist"), and for example, a KIR3DL1 / 2 antagonist antibody or its antigen-binding fragment is administered together with a second antagonist, such as an immune checkpoint inhibitor (e.g., an inhibitor of the PD-1 or PD-L1 pathway), to subjects with diseases in which stimulation of the immune system is expected to be beneficial, such as cancer or infectious diseases. The two antagonists may be administered simultaneously or sequentially, for example, in combination with an immuno-oncology agent as described below. One or more additional therapeutic agents, such as checkpoint modulators, may be added to treatment with a KIR3DL1 / 2-binding antagonist for treating cancer or infectious diseases. In some embodiments, the KIR3DL1 / 2 antagonist is an antibody or antigen-binding fragment that specifically binds to D2 (the intermediate Ig-like domain) of KIR3DL1 / 2, for example, an antibody or antigen-binding fragment that binds to S165, I171, and / or M186 of KIR3DL1 / 2, or inhibits IGSF8 binding via S165, I171, and / or M186.

[0205] In certain embodiments, a KLRC1 / D1 antagonist specifically binds to KLRC1 / D1 ("KLRC1 / D1-binding antagonist"), and for example, a KLRC1 / D1 antagonist antibody or its antigen-binding fragment is administered together with a second antagonist, such as an immune checkpoint inhibitor (e.g., an inhibitor of the PD-1 or PD-L1 pathway), to subjects with diseases in which immune system stimulation is expected to be beneficial, such as cancer or infectious diseases. The two antagonists may be administered simultaneously or sequentially, for example, as described below with respect to combinations of KLRC1 / D1 antagonists and immuno-oncological agents. One or more additional therapeutic agents, such as checkpoint modulators, may be added to treatment with a KLRC1 / D1-binding antagonist to treat cancer or infectious diseases.

[0206] In certain embodiments, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist are administered to a subject, for example, a subject with cancer, either concurrently or sequentially with another treatment. For example, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist may be administered in conjunction with radiotherapy, surgery, or one or more chemotherapy treatments, such as targeted chemotherapy or immunotherapy. Immunotherapy, such as cancer immunotherapy, includes cancer vaccines and immuno-oncology agents.

[0207] The IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist may be, for example, a protein, antibody, antibody fragment, or small molecule that binds to IGSF8, KIR / 3DL1 / 2, or KLRC1 / D1, respectively. The IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist may be an antibody or its antigen-binding fragment that specifically binds to IGSF8, KIR3DL1 / 2, or KLRC1 / D1, respectively.

[0208] In certain embodiments, a method for treating a subject with cancer includes administering to the subject with cancer an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, such as an IGSF8 antibody and / or a KIR3DL1 / 2 antibody and / or a KLRC1 / D1 antibody, and one or more immuno-oncological agents, such as an immune checkpoint inhibitor.

[0209] Immunotherapy, such as therapy using immuno-oncological agents, is effective in enhancing, stimulating, and / or upmodulating the immune response in a target. In one embodiment, the administration of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist together with an immuno-oncological agent (e.g., a PD-1 inhibitor) has a synergistic effect in the treatment of cancer, for example, in inhibiting tumor growth.

[0210] In one embodiment, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody of the present invention or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist are administered sequentially before the administration of the immuno-oncological agent. In one embodiment, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody of the present invention or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist are administered concurrently with the immuno-oncological agent (e.g., a PD-1 inhibitor). In a further embodiment, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody of the present invention or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist are administered sequentially after the administration of the immuno-oncological agent (e.g., a PD-1 inhibitor).

[0211] The administration of the two drugs may be initiated at intervals of, for example, 30 minutes, 60 minutes, 90 minutes, 120 minutes, 3 hours, 6 hours, 12 hours, 24 hours, 36 hours, 48 ​​hours, 3 days, 5 days, 7 days, or one or more weeks, or the administration of the second drug may be initiated after the administration of the first drug, for example, 30 minutes, 60 minutes, 90 minutes, 120 minutes, 3 hours, 6 hours, 12 hours, 24 hours, 36 hours, 48 ​​hours, 3 days, 5 days, 7 days, or one or more weeks.

[0212] In certain embodiments, an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist and an immuno-oncological agent (e.g., a PD-1 inhibitor) are administered to the patient simultaneously, for example, by simultaneous infusion over 30 or 60 minutes. The IGSF8 antagonist can be co-formulated with the immuno-oncological agent (e.g., a PD-1 inhibitor).

[0213] Examples of immuno-oncological agents include, for example, small molecule drugs, antibodies or their fragments, or other biological or small molecules. Examples of biological immuno-oncological agents include, but are not limited to, antibodies, antibody fragments, vaccines, and cytokines. In one embodiment, the antibody is a monoclonal antibody. In a particular embodiment, the monoclonal antibody is a humanized antibody or human antibody.

[0214] In one embodiment, an immuno-oncological agent is either an (i) agonist of a stimulating (including co-stimulating) molecule (e.g., a receptor or ligand) or an (ii) antagonist of an inhibitory (including co-inhibiting) molecule (e.g., a receptor or ligand) on immune cells, such as T cells, both of which result in amplification of the antigen-specific T cell response. In a particular embodiment, an immuno-oncological agent is either an (i) agonist of a stimulating (including co-stimulating) molecule (e.g., a receptor or ligand) or an (ii) antagonist of an inhibitory (including co-inhibiting) molecule (e.g., a receptor or ligand) on cells involved in innate immunity, where the immuno-oncological agent enhances innate immunity. Such immuno-oncological agents are often referred to as immune checkpoint modulators, such as immune checkpoint inhibitors or immune checkpoint stimulators.

[0215] In certain embodiments, immuno-oncological agents target stimulating or inhibitory molecules that are members of the immunoglobulin superfamily (IgSF). For example, immuno-oncological agents target (or specifically bind to) members of the B7 family of membrane-bound ligands, including B7-1, B7-2, B7-H1 (PD-L1), B7-DC (PD-L2), B7-H2 (ICOS-L), B7-H3, B7-H4, B7-H5, and B7-H6, or co-stimulatory or co-inhibitory receptors that specifically bind to members of the B7 family. Immuno-oncological agents may also target members of the TNF family of membrane-bound ligands or co-stimulatory or co-inhibitory receptors that specifically bind to them. Exemplary TNF and TNFR family members that can be targeted by immuno-oncology agents include CD40 and CD40L, OX-40, OX-40L, GITR, GITRL, CD70, CD27L, CD30, CD30L, 4-1BBL, CD137(4-1BB), TRAIL / Apo2-L, TRAILR1 / DR4, TRAILR2 / DR5, TRAILR3, TRAILR4, OPG, RANK, RANKL, TWEAKR / Fnl4, TWEAK, BAFFR, EDAR, XEDAR, TACI, APRIL, BCMA, LTfiR, LIGHT, DcR3, HVEM, VEGI / TL1A, TRAMP / DR3, EDAR, EDA1, XEDAR, EDA2, TNFR1, lymphotoxin α / TNβ, TNFR2, TNFa, LTfiR, and lymphotoxin a Examples include 1β2, FAS, FASL, RELT, DR6, TROY, and NGFR. Immuno-oncological agents that can be used in combination with IGSF8 antagonists to treat cancer include, for example, IgSF members, such as B7 family members, B7 receptor family members, TNF family members, or TNFR family members, or antibodies targeting the above.

[0216] In one embodiment, the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist are (i) antagonists of proteins that inhibit T cell activation (e.g., immune checkpoint inhibitors), e.g., CTLA-4, PD-1, PD-L1, PD-L2, LAG-3, TIM3, galectin-9, CEACAM-1, BTLA, CD69, galectin-1, TIGIT, (ii) administered together with one or more agonists of proteins that stimulate T cell activation, such as (ii) CD113, GPR56, VISTA, B7-H3, B7-H4, 2B4, CD48, GARP, PDIH, LAIR1, TIM-1, TIM-4, and PSGL-1, as well as (ii) one or more of the following: B7-1, B7-2, CD28, 4-1BB (CD137), 4-1BBL, ICOS, ICOS-L, OX40, OX40L, GITR, GITRL, CD70, CD27, CD40, CD40L, DR3, and CD28H.

[0217] In one embodiment, an immuno-oncological agent is either an inhibitor (i.e., an antagonist) of cytokines that inhibit T cell activation (e.g., IL-6, IL-10, TGF-β, VEGF, and other immunosuppressive cytokines), or an agonist (e.g., the cytokine itself) of cytokines that stimulate T cell activation and immune responses, such as IL-2, IL-7, IL-12, IL-15, IL-21, and IFNα.

[0218] Other agents that can be combined with IGSF8 antagonists (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or KIR3DL1 / 2 antagonists and / or KLRC1 / D1 antagonists to stimulate the immune system, for example, for the treatment of cancer and infectious diseases, include antagonists of inhibitory receptors on NK cells or agonists of activating receptors on NK cells. For example, an anti-IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) can be combined with KIR antagonists, such as KIR3DL1 / 2 antagonists and / or antagonists for KLRC1 / D1.

[0219] Further other agents for combination therapy include agents that inhibit or deplete macrophages or monocytes, non-limiting examples of which include CSF-IR antagonists, such as CSF-IR antagonist antibodies, e.g., RG7155 (International Publication No. 1 / 70024, International Publication No. 11 / 107553, International Publication No. 11 / 131407, International Publication No. 13 / 87699, International Publication No. 13 / 119716, International Publication No. 13 / 132044) or FPA008 (International Publication No. 11 / 140249, International Publication No. 13169264, International Publication No. 14 / 036357).

[0220] Other immuno-oncological drugs include those that inhibit TGF-β signaling.

[0221] Additional agents that may be used in combination with IGSF8 antagonists (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or KIR3DL1 / 2 antagonists and / or KLRC1 / D1 antagonists include agents that enhance tumor antigen presentation, such as dendritic cell vaccines, GM-CSF-secreting cell vaccines, CpG oligonucleotides, and imiquimod, or therapeutic agents that enhance the immunogenicity of tumor cells (e.g., anthracyclines).

[0222] The IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody of the present invention or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist may also be combined with other therapies. Further examples of other therapies include therapeutic agents that deplete or block Treg cells, such as agents that specifically bind to CD25.

[0223] Another therapy that may be combined with the IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody of the present invention or its antigen-binding fragment) and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist is a therapeutic agent that inhibits metabolic enzymes such as indoleamine dioxygenase (IDO), dioxygenase, arginase, or nitric oxide synthase.

[0224] Other classes of agents that may be used include agents that inhibit the formation of adenosine or agents that inhibit the adenosine A2A receptor.

[0225] Other therapies that may be combined with the IGSF8 antagonist and / or the KIR3DL1 / 2 antagonist and / or the KLRC1 / D1 antagonist for treating cancer include therapies that reverse / prevent T cell anergy or depletion, and therapies that activate innate immunity and / or cause inflammation at the tumor site.

[0226] IGSF8 antagonists (e.g., the anti-IGSF8 monoclonal antibodies or antigen-binding fragments thereof of the present invention) and / or KIR3DL1 / 2 antagonists and / or KLRC1 / D1 antagonists may be combined with each other and / or with more than one immuno-oncology agent (e.g., immune checkpoint inhibitors), for example, in combination with a combinatorial approach targeting multiple elements of immune pathways such as one or more of the following: therapeutic agents that enhance tumor antigen presentation (e.g., dendritic cell vaccines, cell vaccines secreting GM-CSF, CpG oligonucleotides, imiquimod); therapies that inhibit negative immune regulation, for example, by inhibiting the CTLA-4 and / or PD1 / PD-L1 / PD-L2 pathways and / or depleting or blocking Tregs or other immunosuppressive cells; therapeutic agents that stimulate positive immune regulation, for example, therapeutic agents that stimulate positive immune regulation in combination with agonists that stimulate the CD-137, OX-40 and / or GITR pathways and / or stimulate T cell effector functions; therapeutic agents that globally increase the frequency of anti-tumor T cells; therapeutic agents that deplete or inhibit Tregs, e.g., Tregs in tumors, for example, using antagonists of CD25 (e.g., daclizumab) or by depletion of anti-CD25 beads ex vivo; therapeutic agents that affect the function of suppressive myeloid cells in tumors; therapeutic agents that enhance the immunogenicity of tumor cells (e.g., anthracyclines); trafficking of adoptive T cells or NK cells, e.g., genetically modified cells, e.g., cells modified by chimeric antigen receptors (CAR-T therapy), etc.; therapies that inhibit metabolic enzymes such as indoleamine dioxygenase (IDO), dioxygenase, arginase or nitric oxide synthase; therapeutic agents that reverse / prevent T cell anergy or depletion; therapeutic agents that activate innate immunity and / or cause inflammation at the tumor site; administration of immunostimulatory cytokines or blockade of immunosuppressive cytokines.

[0227] For example, IGSF8 antagonists (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or KIR3DL1 / 2 antagonists and / or KLRC1 / D1 antagonists can be used in conjunction with one or more agonists that link positive costimulatory receptors; one or more antagonists (blocking agents) that weaken signaling via inhibitory receptors, e.g., antagonists that overcome distinct immunosuppressive pathways within the tumor microenvironment (e.g., blocking PD-L1 / PD-1 / PD-L2 interactions); one or more agents that systemically increase the frequency of anti-tumor immune cells, e.g., T cells, deplete or inhibit Tregs (e.g., by inhibiting CD25); one or more agents that inhibit metabolic enzymes such as IDO; one or more agents that reverse / prevent T cell anergy or depletion; and one or more agents that activate innate immunity and / or cause inflammation at the tumor site.

[0228] In one embodiment, subjects with a disease that may benefit from stimulation of the immune system, such as cancer or infectious disease, are treated by administration of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist and an immuno-oncological agent, the immuno-oncological agent being a CTLA-4 antagonist, such as an antagonist CTLA-4 antibody. Suitable CTLA-4 antibodies include, for example, YERVOY (ipilimumab) or tremelimumab.

[0229] In one embodiment, subjects with diseases that may benefit from stimulation of the immune system, such as cancer or infectious diseases, are treated by administration of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, and an immuno-oncological agent, the immuno-oncological agent being a PD-1 antagonist, such as an antagonist PD-1 antibody. Suitable PD-1 antibodies include, for example, OPDIVO (nivolumab), KEYTRUDA (pembrolizumab), or MEDI-0680 (AMP-514; WO2012 / 145493). The immuno-oncological agent may also include pizilizumab (CT-011). Another approach targeting the PD-1 receptor is a combination protein consisting of the extracellular domain (B7-DC) of PD-L2 fused to the Fc portion of IgGl, which is called AMP-224.

[0230] In one embodiment, a subject having a disease that may benefit from stimulation of the immune system, such as cancer or an infectious disease, is treated by administration of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, and an immuno-oncological agent, where the immuno-oncological agent is a PD-L1 antagonist, such as an antagonistic PD-L1 antibody. Suitable PD-L1 antibodies include, for example, MPDL3280A (RG7446; International Publication No. 2010 / 077634), durvalumab (MEDI4736), BMS-936559 (International Publication No. 2007 / 005874), MSB0010718C (International Publication No. 2013 / 79174), or rHigM12B7.

[0231] In one embodiment, a subject having a disease that may benefit from stimulation of the immune system, such as cancer or an infectious disease, is treated by administration of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, and an immuno-oncological agent, where the immuno-oncological agent is a LAG-3 antagonist, such as an antagonistic LAG-3 antibody. Suitable LAG3 antibodies include, for example, BMS-986016 (International Publication No. 10 / 19570, International Publication No. 14 / 08218), or IMP-731 or IMP-321 (International Publication No. 08 / 132601, International Publication No. 09 / 44273).

[0232] In one embodiment, a subject with a disease that can benefit from stimulation of the immune system, such as cancer or an infectious disease, is treated by administration of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, and an immuno-oncological agent, where the immuno-oncological agent is a CD137(4-1BB) agonist, such as an agonist CD137 antibody. Suitable CD137 antibodies include, for example, urelumab or PF-05082566 (International Publication No. 12 / 32433).

[0233] In one embodiment, a subject having a disease that can benefit from stimulation of the immune system, such as cancer or an infectious disease, is treated by administration of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, and an immuno-oncological agent, where the immuno-oncological agent is a GITR agonist, such as an agonist GITR antibody. Suitable GITR antibodies include, for example, TRX-518 (International Publication No. 06 / 105021, International Publication No. 09 / 009116), MK-4166 (International Publication No. 11 / 028683), or the GITR antibodies disclosed in International Publication No. 2015 / 031667.

[0234] In one embodiment, a subject having a disease that may benefit from stimulation of the immune system, such as cancer or an infectious disease, is treated by administration of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, and an immuno-oncological agent, where the immuno-oncological agent is an OX40 agonist, such as an agonist OX40 antibody. Suitable OX40 antibodies include, for example, MEDI-6383, MEDI-6469, or MOXR0916 (RG7888; International Publication No. 06 / 029879).

[0235] In one embodiment, a subject having a disease that can benefit from stimulation of the immune system, such as cancer or an infectious disease, is treated by administration of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, and an immuno-oncological agent, where the immuno-oncological agent is a CD40 agonist, such as an agonist CD40 antibody. In a particular embodiment, the immuno-oncological agent is a CD40 antagonist, such as an antagonist CD40 antibody. Suitable CD40 antibodies include, for example, lucatumumab (HCD122), dacetuzumab (SGN-40), CP-870, 893, or tyrob 7 / 4.

[0236] In one embodiment, a subject having a disease that may benefit from stimulation of the immune system, such as cancer or an infectious disease, is treated by administration of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, and an immuno-oncological agent, where the immuno-oncological agent is a CD27 agonist, such as an agonist CD27 antibody. A suitable CD27 antibody is, for example, valirumab (CDX-1127).

[0237] In one embodiment, a disease that may benefit from stimulation of the immune system, for example, a subject having cancer or an infectious disease, is treated by administration of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, and an immuno-oncological agent, where the immuno-oncological agent is MGA271(~B7H3) (International Publication No. 11 / 109400).

[0238] In one embodiment, a subject having a disease that may benefit from stimulation of the immune system, such as cancer or an infectious disease, is treated by administration of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, and an immuno-oncological agent, where the immuno-oncological agent is a KIR antagonist, such as lirilumab.

[0239] In one embodiment, a subject having a disease that may benefit from stimulation of the immune system, such as cancer or an infectious disease, is treated by administration of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, and an immuno-oncological agent, where the immuno-oncological agent is an IDO antagonist. Suitable IDO antagonists include, for example, INCB-024360 (International Publication Nos. 2006 / 122150, 07 / 75598, 08 / 36653, and 08 / 36642), indoximod, NLG-919 (International Publication Nos. 09 / 73620, 09 / 1156652, 11 / 56652, and 12 / 142237), or F001287.

[0240] In one embodiment, a subject having a disease that may benefit from stimulation of the immune system, such as cancer or an infectious disease, is treated by administration of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, and an immuno-oncological agent, where the immuno-oncological agent is a Toll-like receptor agonist, such as a TLR2 / 4 agonist (e.g., Bacillus Calmette-Guerin), a TLR7 agonist (e.g., Hiltonol or Imiquimod), a TLR7 / 8 agonist (e.g., Resiquimod), or a TLR9 agonist (e.g., CpG7909).

[0241] In one embodiment, a subject having a disease that may benefit from stimulation of the immune system, such as cancer or an infectious disease, is treated by administration of an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, and an immuno-oncological agent, where the immuno-oncological agent is a TGF-β inhibitor, such as GC1008, LY2157299, TEW7197, or IMC-TR1.

[0242] Another therapy, which may be combined with an IGSF8 antagonist (e.g., the anti-IGSF8 monoclonal antibody or its antigen-binding fragment of the present invention) and / or a KIR3DL1 / 2 antagonist and / or a KLRC1 / D1 antagonist, is a therapeutic antibody, such as a therapeutic antibody effective in treating cancer. Exemplary, but non-limiting, therapeutic antibodies include 3F8, 8H9, avagovomab, absiximab, abituzumab, abrazekimab, abrilumab, actokisumab, adalimumab, adekatumumab, aducanumab, afasebicumab, aferimomab, aracizumab pegol, alemtuzumab, alirocumab, artumomab penteate, amatsuximab, amivantamab, anatumomab mafenatox, andecaliximab, anetumab tansine, aniflorumab, and Lukinzumab, apolizumab, apultumab ixadotin, alsitumomab, ascrimbakumab, aselizumab, atezolizumab, atidolotoxumab, atinumab, atrolimumab, avelumab, adintuxizumab vedotin, bapineozumab, basiliximab, bavituximab, BCD-100, vectumomab, begeromab, verantamab mahodotin, belimumab, bemarituzumab, benralizumab, berlimatoxumab, bermekimab, bersanlimab, bertilimumab Becilesomab, bevacizumab, bezlotoxumab, bisilomab, bimaglumab, bimekizumab, vilutamimab, vibatuzumab, preserumab, blinatumomab, brontubetomab, brosozumab, vococizumab, brazicumab, brentuximab vedotin, briakinumab, brodalumab, brolucizumab, bronticutuzumab, brosumab, kabilizumab, camidanrumab tesirin, camrelizumab, canakinumab, cantuzumab meltansine, cantuzumabrabutansine , caplacizumab, capromab, carrumab, carotuximab, katumakisomab, cBR-doxorubicin immunoconjugate, sedelizumab, semiprimab, cergutuzumab amnaleukin, certolizumab pegol, cetrelimab, cetuximab, sibisatamab, silimutuzumab, sitatuzumab bogatox, sixtumumab, crazakizumab, clenoliximab, cribatuzumab tetraxetan, codlituzumab, cofetuzumab peridotin, coltuximab labutancin,Conatumumab, Concizumab, Cosflobiximab, Crenezumab, Chryzanlizumab, Clotedumab, CR6261, Xatuzumab, Dasetuzumab, Dacrizumab, Darotuzumab, Dapirolizumab Pegol, Daratumumab, Dectrecumab, Demcizumab, Denintuzumab Mahodotin, Denosumab, Depatuxizumab Mahodotin, Delrotuximab Biotin, Detumomab, Dezamizumab, Dinutuximab, Ziridabu Mab, Domaglozumab, Dorlimomab Aritox, Dostalurimab, Drodizumab, DS-8201, Durigotuzumab, Dupilumab, De rulvalumab, dusigituzumab, duvortuxizumab, eclomeximab, eculizumab, edovacomab, edrecolomab, efalizumab, efangumab, erderumab, erezanumab, elgemzumab, elotuzumab, elcilimomab, emuctuzumab, emapalmab, emibetuzumab, emicizumab, enapotamab vedotin, enabatuzumab, enfortumab vedotin, enrimomab pegol, enobrituzumab, enokizumab, enochicumab, encituximab, epitumomab citucetan, epratuzumab, eptinezumab, erenumab, el Lizumab, Erzmaxomab, Etalacizumab, Etigirimab, Etrolizumab, Evinacumab, Evolocumab, Exvivirumab, Fanoresomab, Faralimomab, Falicimab, Faretuzumab, Facinumab, FBTA05, Felbizumab, Fezakinumab, Fivatuzumab, Ficlatuzumab, Figitumumab, Filibumab, Flambotumab, Fletituzumab, Flotetuzumab, Fontlizumab, Foralumab, Folavirumab, Fremanezumab, Fresolimmab, Flobosimab, Flunebetomab, Fluranumab, Futuximab, Galcane Zumab, Galiximab, Gancotamab, Ganitumab, Gantenerumab, Gatipotuzumab, Gabirimomab, Gezibumab, Gemtuzumab Ozogamicin, Gebokizumab, Zilvetomab, Dimcirumab, Dilentuximab, Glenbatumumab Vedotin, Golimumab, Gomiliximab, Goslanemab, Guselkumab, Ranalumab, Ibalizumab, IBI308, Ibritumomab Chiuxetan, Ikulucumab, Idarucizumab, Ifabotuzumab, Igobomab, Iradatuzumab Vedotin, IMAB363, Imarumab, Imaprelimab, Imsilomab, ImugatuzumabInclacumab, indatuximab tansine, indusatumab vedotin, inebilizumab, infliximab, intetumumab, inorimomab, inotuzumab ozogamicin, ipilimumab, Iomab-B, iratumumab, isatuximab, iscarimab, istilatumab, itorizumab, ixekizumab, keriximab, rabetuzumab, lacunotuzumab, radilatuzumab vedotin, lamparizumab, lanaderumab, landgrozumab, laprituximab emtansine, larcabiximab, lebrikizumab, remaresomab, lendarizumab, lembe Lubimab, lenzirumab, reldelimab, leronlimab, resofabumab, letrizumab, lexatumumab, rivivirumab, rifastuzumab vedotin, rigerizumab, loncatuximab tesirin, rosatuxizumab vedotin, rilotomab satetraxetan, lintuzumab, lirirumab, rodelcizumab, lokivetomab, rorbotuzumab meltansine, lucatumumab, rulizumab pegol, lumiliximab, lumuretuzumab, lupalzumab, lupalzumab amadotin, lutikizumab, mapatumumab, marjetuximab, malstacimab, maslimomab, Mabrilimumab, matsuzumab, mepolizumab, meterimumab, milatuzumab, minretumomab, mirikizumab, milbetuximab sorabtansine, mitumomab, modotuximab, mogamulizumab, monalizumab, mololimumab, mosnetuzumab, motabizumab, moxetumomab pasdotox, muromonab-CD3, nacolomabutafenatox, namilumab, naptumomab estafenatox, naratuximab emtansine, narunatumab, natalizumab, nabixixizumab, navibumab, naxitamab, nevacumab, necitumumab, nemolizumab, NEOD 001, Nerelimomab, Nesbakumab, Netakimab, Nimotuzumab, Nilsevimab, Nivolumab, Nofetumomab Merpentan, Oviltoxakimab, Obinutuzumab, Okalatuzumab, Ocrelizumab, Odurimomab, Ofatumumab, Oralatuzumab, Olekurumab, Orendalizumab, Orokizumab, Omalizumab, Ombrutamab, OMS721, Onartuzumab, Ontuxizumab, Onbachirimab, Opicinumab, Oportuzumab Monatox, Olegobomab, Orticumab, Oterixizumab, Ochirimab, Otreltuzumab, Oxerumab,Ozanezumab, ozoralizumab, padibaximab, palivizumab, pamrebrumab, panitumumab, pancomab, panobacumab, pulsatuzumab, pascolizumab, pasotuxizumab, pateclizumab, patrizumab, PDR001, pembrolizumab, pemtumomab, perakizumab, pasutuzumab, paxerizumab, pidilizumab, pinatuzumab vedotin, pintumomab, prakmab, prezalumab, prozarizumab, pogalizumab, polatuzumab vedotin, ponezumab, polgabiximab, pracinezumab, prezarizumab, priliximab, p Ritoxaximab, Pritumumab, PRO140, Kirizumab, Lacosumomab, Radrezumab, Rafibirumab, Lalpancizumab, Ramucirumab, Lanebetomab, Ranibizumab, Laxibakumab, Labagalimab, Laburizumab, Refanezumab, Legavirumab, REGN-EB, Relatrimab, Remtolumab, Reslizumab, Rilotumumab, Linucumab, Risankizumab, Rituximab, Ribabzumab Pegol, Lobatumumab, Rmab, Lorezumab, Romirukimab, Romosozumab, Rontalizumab, Rosmantuzumab, Robalpituzumab Tecilin, Roberi Zumab, Rozanolixizumab, Luprizumab, SA237, Sacituzumab Govitecan, Samalizumab, Samlotamab Vedotin, Sarilumab, Satralizumab, Satsumomab Pendetide, Secukinumab, Sericrelumab, Cerivantuzumab, Cetoxaximab, Setorusumab, Sevilumab, Cibrotuzumab, SGN-CD19A, SHP647, Sifalimumab, Siltuximab, Simtuzumab, Ciprizumab, Siltratumab Vedotin, Silkumab, Sofituzumab Vedotin, Solanezumab, Solitomab, Sonepcizumab, Sontuzumab, Spartalizumab, Stamulumab, threzomab, subtabumab, stimulimab, subizumab, subratoxumab, tavarumab, tacuzumab tetraxetan, tadocizumab, talakotsuzumab, talizumab, taluketamab, tamtuvetomab, tanezumab, tapritumomab paptox, tarexuzumab, tavolimab, tecristamag, tefivazumab, terimomab aritox, terisotuzumab, terisotuzumab vedotin, tenatumomab, teneriximab, teprizumab, tepositamab, teprotumumab, tesidorumab, tetulomab, tezeperumab, TGN1412, tibrizumab,Childrakizumab, tigatuzumab, timigutuzumab, timorumab, tilagorumab, tilagotumab, tislerizumab, tisotumab vedotin, TNX-650, tocilizumab, tomzotuximab, tralizumab, tosatoxumab, tositumomab, tobetumab, tralokinumab, trastuzumab, trastuzumab duocalmazine, trastuzumab emtansine, TRBS07, tregalizumab, tremelimumab, trevoglumab, tucotsuzumab cermoloukin, tubilumab, ubrituximab, urocuprumab, urerumab, urtoxazumab, ustekinumab, utomirumab, vadasutuximab tarili Examples include banarimab, bundutuzumab vedotin, bunchikutuzumab, vanucizumab, bapariximab, valisakumab, valrirumab, baterizumab, vedolizumab, bertuzumab, bepalimomab, besenkumab, vizilizumab, bovalilizumab, borosiximab, bonlerorizumab, voplaterimab, borsetuzumab mahodotin, botumumab, bunakizumab, xentuzumab, XMAB-5574, zaltumumab, zanorimumab, zatuximab, xenoctuzumab, diralimumab, zolbetuximab (=IMAB362, claudicimab), zolimomab aritox, or combinations thereof.

[0243] 6. Exemplary IGSF8 Antagonist In some embodiments, the IGSF8 antagonist is an IGSF8 antibody. In some embodiments, the IGSF8 antagonist for treating cancer may be a non-antibody protein, such as soluble IGSF8 or a portion thereof (e.g., ECD) that inhibits the interaction between IGSF8 and its ligand, and optionally further comprising a fusion partner in the form of a fusion molecule.

[0244] In some embodiments, the IGSF8 antagonist is a soluble ECD of KIR3DL1 / 2 that binds to IGSF8, such as the D2 domain of KIR3DL1 / 2 or a fragment thereof, which may further include a fusion partner, such as a sequence tag (e.g., His tag, FLAG tag, etc.) as needed. Such an IGSF8 antagonist can bind to IGSF8 and block its binding to the KIR3DL1 / 2 receptor on NK cells, thus blocking the IGSF8-mediated downregulation of NK cell activity and / or viability.

[0245] In some embodiments, the IGSF8 antagonist is a soluble ECD of KLRC1 / D1 that binds to IGSF8, such as the ECD of KLRC1 or KLRD1, or a fragment thereof, which may further include a fusion partner, such as a sequence tag (e.g., His tag, FLAG tag, etc.) as needed. Such an IGSF8 antagonist can bind to IGSF8 and block its binding to the KLRCx1 / D1 receptor on NK cells, thus blocking the IGSF8-mediated downregulation of NK cell activity and / or viability.

[0246] In other embodiments, the antagonist may also be a small molecule or a small peptide.

[0247] IGSF8 antibody One aspect of the present invention provides a monoclonal antibody specific to IGSF8. In certain embodiments, the monoclonal antibody is specific to the extracellular domain (ECD) of IGSF8. In certain embodiments, the monoclonal antibody is specific to the Ig-V set extracellular domain (D1 domain) of IGSF8. In some embodiments, an antibody is provided that blocks the binding of IGSF8 to its ligand. In certain embodiments, the monoclonal antibody inhibits the binding of IGSF8 to KIR3DL2 and / or KIR3DL1, for example, inhibiting the binding of IGSF8 to residues S165, I171, and / or M186. In certain embodiments, the monoclonal antibody inhibits the binding of IGSF8 to KLRC1 / D1. In certain embodiments, the monoclonal antibody exhibits heterogeneous reactivity, for example, the monoclonal antibody binds to both human and mouse IGSF8. In certain embodiments, the monoclonal antibody is specific to human IGSF8. In some embodiments, the IGSF8 antibody inhibits IGSF8-mediated signaling. In certain embodiments, the monoclonal antibody competes with any of the anti-IGSF8 antibodies disclosed herein for binding to IGSF8. In certain embodiments, the monoclonal antibody binds to the same IGSF8 epitope as any of the anti-IGSF8 antibodies disclosed herein.

[0248] In some embodiments, the IGSF8 antibody of the present invention has a methylation level of ≤1 μM, ≤100 nM, ≤10 nM, ≤1 nM, ≤0.1 nM, ≤0.01 nM, or ≤0.001 nM (for example, 10) relative to human IGSF8. -8 M or less, for example, 10 -8 M~10 -13 M, for example, 10 -9 M~10 -13 The dissociation constant (K) of M d) has. In certain embodiments, the IGSF8 antibody has a dissociation constant (Kd) for IGSF8, for example, ≤1 μM, ≤100 nM, ≤10 nM, ≤1 nM, ≤0.1 nM, ≤0.01 nM, or ≤0.001 nM (for example, 10 -8 M or less, for example, 10 -8 M~10 -13 M, for example, 10 -9 M~10 -13 M) is the answer.

[0249] In some embodiments, an IGSF8 antibody having any of the features provided herein inhibits at least 25%, 50%, 75%, 80%, 90%, or 100% of IGSF8 signaling, for example, signaling via KIR3DL1 / 2 and / or KLRC1 / D1. For example, KIR3DL1 / 2 and / or KLRC1 / D1 signaling, when bound to IGSF8, can be assayed in NK cells based on IFNγ secretion, and such secretion can be analyzed using standard techniques such as ELISA. In some embodiments, an IGSF8 antibody inhibits signaling in NK cells in any one of the signaling pathways described in Figure 2D (e.g., cell cycle, DNA replication, etc.) or Figure 2E (e.g., PRF1, GZMB, or GZMA).

[0250] In some embodiments, the IGSF8 antibody of the present invention may be any of the antibodies described herein, such as C1-C39 or C30-C39 described in Example 7, plus any one of the antibodies L1-01-L1-033 and L2-01-L2-010 (all incorporated herein by reference) described in Example 24, plus any of the antibodies described in this section.

[0251] Unless explicitly stated, all antibodies and CDR sequences are based on the IMGT numbering scheme, except for C1-C29 which are annotated by the Kabat numbering scheme (while others, such as those based on C30-C39 and L1 / L2 derivatives, are based on the IMGT numbering scheme). In addition, sequence consensus / motifs of the heavy chain only after C39, as well as CDR sequences (L1 / L2 derivatives) in CDR region mutation analysis, are also based on the IMGT numbering scheme.

[0252] Using the HCVR CDR1-3 sequences of high-affinity anti-IGSF8 antibody C30-C39 as query sequences, numerous similar CDR sequences were identified in patented human antibody libraries. Antibodies with such small CDR variations are also anti-IGSF8 antibodies of the present invention that are specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD).

[0253] Similarly, using the LCVR CDR1-3 sequences of high affinity anti-IGSF8 antibody C30-C39 as query sequences, numerous similar CDR sequences were identified in patented human antibody libraries, and antibodies with such small CDR variations are also anti-IGSF8 antibodies of the present invention that are specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD).

[0254] Accordingly, in some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises (a) a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 469, 470, and 471, respectively, which is similar to and encompasses the HCVR CDR1-3 of the monoclonal antibody C30 / B34; and / or (b) a light chain variable region (LCVR) comprising LCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 562, 563, and 564, respectively, which is similar to and encompasses the LCVR CDR1-3 of the monoclonal antibody C30 / B34. Sequence ID 469: G Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 A, where Xaa1=F or Y; Xaa2=S or T; Xaa3=L, F or I; Xaa4=R, S or I; Xaa5=D or S; and Xaa6=Y or S. Sequence ID 470: I Xaa1 GSGG Xaa2 T, where Xaa1 = S or T, and Xaa2 = N or S. Sequence ID 471: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 Xaa7 Xaa8, where Xaa1=E, A or S, Xaa2=R, L or S, Xaa3=W, A, Y, V, G or S, Xaa4=R, L or S, Xaa5=L, Y, P, T, I, N, K, H or Q, Xaa6=L, V, F, I, G, R or H, Xaa7=A, Y, V or any acidic residue (D / E), and Xaa8=Y, A, T, P, K, S or Q. Sequence ID 562: Xaa1 Xaa2 Xaa3 H Xaa4 Y, where Xaa1=K, Q, P or H, Xaa2=S, V, I or R, Xaa3=N, S, L, I or M, Xaa4=K, N or T, Sequence ID 563: AAS, and, Sequence ID 564: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 P Xaa7 Xaa8, where Xaa1=L, Q, K or H, Xaa2=L, Q, K or H, Xaa3=S, I or R, Xaa4=Y or F, Xaa5=P, N, S or T, Xaa6=P, N, S or T, Xaa7=L, I or R, Xaa8=P, N, S or T.

[0255] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises (a) a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 472, 473, and 474, respectively, which is similar to and encompasses the HCVR CDR1-3 of the monoclonal antibody C31 / B46; and / or (b) a light chain variable region (LCVR) comprising LCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 565, 566, and 567, respectively, which is the LCVR CDR1-3 of the monoclonal antibody C31 / B46. Sequence ID 472: GFTFSTYG, Sequence ID 473:IWDDGSYK, and, Sequence ID 474: A Xaa1 GYS Xaa2 S Xaa3 Xaa4 A Xaa5, where Xaa1=V or G, Xaa2=D or Y, Xaa3=Y, D or S, Xaa4=R, L or M, Xaa5=L, I or S. Sequence ID 565: QGISTF, Sequence ID 566: AAS, and, Sequence ID 567: QQTYSTQWT.

[0256] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises (a) a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 475, 476, and 477, respectively, which is similar to and encompasses the HCVR CDR1-3 of the monoclonal antibody C32 / B104; and / or (b) a light chain variable region (LCVR) comprising LCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 568, 569, and 570, respectively, which is the LCVR CDR1-3 of the monoclonal antibody C32 / B104. Sequence ID 475: GYTFTNDI, Sequence ID 476: INAGYGNT, and, Sequence ID 477: ARGYYRSPTW Xaa1 D Xaa2, where Xaa1 = F or I, and Xaa2 = W or Y. Sequence ID 568: QSISSW, Sequence ID 569: KAS, and, Sequence ID 570: QQYGDYPYT.

[0257] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises (a) a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 478, 479, and 480, respectively, which is similar to and encompasses the HCVR CDR1-3 of the monoclonal antibody C33 / 1C2; and / or (b) a light chain variable region (LCVR) comprising LCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 571, 572, and 573, respectively, which is the LCVR CDR1-3 of the monoclonal antibody C33 / 1C2. Sequence ID 478: GFTFSTYG, Sequence ID 479: IWDDGSYK, and, Sequence ID 480: ARD Xaa1 S Xaa2 W Xaa3 YAFD Xaa4, where Xaa1=G or C, Xaa2=V or G, Xaa3=V or G, and Xaa4=L or I. Sequence ID 571: Xaa1 D Xaa2 Xaa3 Xaa4 Y, where Xaa1 = K, Q, P, or H; Xaa2 = S, N, I, or L; Xaa3 = S, I, or R; Xaa4 = any acidic residue (D / E). Sequence ID 572: DAA, and, Sequence ID 573: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 Xaa7 Xaa8 Xaa9, where Xaa1=L, Q, K or H, Xaa2=Q, K, H or L, Xaa3=Y, S, D or F, Xaa4=V, A or any acidic residue (D / E), Xaa5=S, I or R, Xaa6=L, F or V, Xaa7=H, P or T, Xaa8=Y, S, F or D, Xaa9=P, N, S or T.

[0258] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises (a) a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 481, 482, and 483, respectively, which is similar to and encompasses the HCVR CDR1-3 of the monoclonal antibody C34 / 1D7; and / or (b) a light chain variable region (LCVR) comprising LCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 574, 575, and 576, respectively, which is similar to and encompasses the LCVR CDR1-3 of the monoclonal antibody C34 / 1D7. Sequence ID 481: GFT Xaa1 Xaa2 S Xaa3 A, where Xaa1=V or F, Xaa2=N or S, and Xaa3=F or Y, Sequence ID 482: I Xaa1 GSGG Xaa2 T, where Xaa1 = S or T, and Xaa2 = S or G, Sequence ID 483: AR Xaa1 V Xaa2 GYGAF Xaa3 Xaa4, where Xaa1 = any acidic residue (D / E), Xaa2 = any acidic residue (D / E), Xaa3 = A or any acidic residue (D / E), and Xaa4 = L or I. Sequence ID 574: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Y, where Xaa1=Q, P or any basic residue (R / H / K), Xaa2=S, N or T, Xaa3=N, S, L, I or M, Xaa4=H, R, I or S, Xaa5=H, N, D, S, K, T or I, Sequence ID 575: GAS, and, Sequence ID 576: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 Xaa7 Xaa8 Xaa9, where Xaa1=H, Q, K, L or P, Xaa2=H, E, Q, K, L or P, Xaa3=N, A, S, T or P, Xaa4=Y, S, V, L or F, Xaa5=S, I or R, Xaa6=V, A or any acidic residue (D / E), Xaa7=A, Q, K, R, T or P, Xaa8=Y or F, Xaa9=P, N, S or T.

[0259] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises (a) a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 484, 485, and 486, respectively, which is similar to and encompasses the HCVR CDR1-3 of the monoclonal antibody C35 / 1B1; and / or (b) a light chain variable region (LCVR) comprising LCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 577, 578, and 579, respectively, which is the LCVR CDR1-3 of the monoclonal antibody C35 / 1B1. Sequence ID 484: GFTF Xaa1 Xaa2 Xaa3 A, where Xaa1=R, N or S, Xaa2=D or S, and Xaa3=F or Y, Sequence ID 485: I Xaa1 GSGG Xaa2 T, where Xaa1 = S or T, & Xaa2 = N, S or G, Sequence ID 486: A Xaa1 Xaa2 GWE Xaa3 RTPG Xaa4 Xaa5 D Xaa6, where Xaa1=R or S, Xaa2=V or any acidic residue (D / E), Xaa3=V or G, Xaa4=D or Y, Xaa5=L, F or I, and Xaa6=D, Y, H or S. Sequence ID 577: HRIFSY, Sequence ID 578: GAS, and, Sequence ID 579: QQSFSDPYT.

[0260] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (for example, specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises (a) a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 487, 488, and 489, respectively, which is similar to and encompasses the HCVR CDR1-3 of the monoclonal antibody C36 / 1B4', and / or (b) a light chain variable region (LCVR) comprising LCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 580, 581, and 582, respectively, which is similar to and encompasses the LCVR CDR1-3 of the monoclonal antibody C36 / 1B4. Sequence ID 487: GFTFSS Xaa1 A, where Xaa1 = Y or S, Sequence ID 488: ITGSGGST, and, Sequence ID 489: AR Xaa1 Xaa2 Xaa3 Xaa4 L Xaa5 Xaa6, where Xaa1=D or G, Xaa2=R or absent, Xaa3=G or C, Xaa4=A, G or S, Xaa5=any acidic residue (D / E), and Xaa6=L, Y, I or V. Sequence ID 580: Xaa1 Xaa2 Xaa3 H Xaa4 Y, where Xaa1=K, Q, P or H, Xaa2=S, V, I or R, Xaa3=N, S, L, I or M, Xaa4=K, N or T, Sequence ID 581: SAS, and, Sequence ID 582: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 P Xaa7 Xaa8, where Xaa1=L, Q, K or H, Xaa2=L, Q, K or H, Xaa3=S, I or R, Xaa4=Y or F, Xaa5=P, N, S or T, Xaa6=P, N, S or T, Xaa7=L, I or R, Xaa8=P, N, S or T.

[0261] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises (a) a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 490, 491, and 492, respectively, which is similar to and encompasses the HCVR CDR1-3 of the monoclonal antibody C37 / 3F12; and / or (b) a light chain variable region (LCVR) comprising LCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 583, 584, and 585, respectively, which is similar to and encompasses the LCVR CDR1-3 of the monoclonal antibody C37 / 3F12. Sequence ID 490: GFTFSSYS, Sequence ID 491:ISSSSSYI, Sequence ID 492: Xaa1 RXaa2 Xaa3 Xaa4 Xaa5 Xaa6 Xaa7 Xaa8 Xaa9 D Xaa10 Xaa11 Xaa12 Xaa13, where Xaa1=C or G, Xaa2=P or Q, Xaa3=Y or D, Xaa4=Y, A or any acidic residue (D / E), Xaa5=F or L, Xaa6=W or L, Xaa7=S, R or I, Xaa8=C, V or G, Xaa9=W, C or L, Xaa10=W, C or G, Xaa11=Y, F or V, Xaa12=D or A, and Xaa13=H, P or T. Sequence ID 583: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6, where Xaa1=Q, L, P or any basic residue (R / H / K), Xaa2=D, S, G, R, T or I, Xaa3=N, S, L, V, T or I, Xaa4=H, N, S, G, R, T or I, Xaa5=N, A, S, E, T, P or I, Xaa6=Q, D, S or Y, Sequence ID 584: DAS, and, Sequence number 585: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 Xaa7 Xaa8 Xaa9 Xaa10, where Xaa1=N, E, Q, L, P or any basic residue (R / H / K), Xaa2=N, E, Q, L, P or any basic residue (R / H / K), Xaa3=S, G, R, T or I, Xaa4=Y, H, D, S or F, Xaa5=S, G, R, T, I or M, Xaa6=N, A, S, T, P or I, Xaa7=H, L, V, R or I, Xaa8=A, S, Q, T, P or any basic residue (R / H / K), Xaa9=Y, H, N, S, F or any acidic residue (D / E), Xaa10=N, A, S, T or P.

[0262] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises (a) a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 493, 494, and 495, respectively, which is similar to and encompasses the HCVR CDR1-3 of the monoclonal antibody C38 / 2B4; and / or (b) a light chain variable region (LCVR) comprising LCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 586, 587, and 588, respectively, which is similar to and encompasses the LCVR CDR1-3 of the monoclonal antibody C38 / 2B4. Sequence ID 493: GFT Xaa1 Xaa2 Xaa3 Xaa4 A, where Xaa1=F or C, Xaa2=R, N or S, Xaa3=D or S, and Xaa4=F or Y, Sequence ID 494: I Xaa1 GSGG Xaa2 T, where Xaa1 = S or T, and Xaa2 = N, S or G, Sequence number 495: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 Xaa7 Xaa8 Xaa9 Xaa10 Xaa11 Xaa12 Xaa13 Xaa14 Xaa15, where Xaa1=E, A or S, Xaa2=R, S or I, Xaa3=V or G, Xaa4=A or any acidic residue (D / E), Xaa5=D, Y or S, Xaa6=Y or S, Xaa7=R, S or I, Xaa8=V, G or C, Xaa9=L, W, G or C, Xaa10=P, H or T, Xaa11=R, S or I, Xaa12=L, W, C, G or R, Xaa13=L, F, V or C, Xaa14=Y, D or A, and Xaa15=P, H, S or T. Sequence ID 586: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6, where Xaa1=Q, R or L, Xaa2=A, S, N or T, Xaa3=V, F or L, Xaa4=G or D, Xaa5=A, S, K, T or P, Xaa6=Y, L, V, F or I, Sequence ID 587: GVS, and Sequence ID 588: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 P Xaa7 Xaa8, where Xaa1=K, Q, L or H, Xaa2=Q, K, H or L, Xaa3=S, I, T or R, Xaa4=N, H, D or Q, Xaa5=V, A or any acidic residue (D / E), Xaa6=A, G, V, L or F, Xaa7=G, R or L, Xaa8=K, S, P or T.

[0263] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (for example, specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises (a) a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 496, 497, and 498, respectively, which is similar to and encompasses the HCVR CDR1-3 of the monoclonal antibody C39 / 8G4; and / or (b) a light chain variable region (LCVR) comprising LCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 589, 590, and 591, respectively, which is similar to and encompasses the LCVR CDR1-3 of the monoclonal antibody C39 / 8G4. Sequence ID 496: GFTFSSYA, Sequence ID 497: ITGSGGST, and, Sequence ID 498: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 D Xaa7, where Xaa1=A or W, Xaa2=F, P, R or Y, Xaa3=D, H, P or S, Xaa4=R or S, Xaa5=D, I or N, Xaa6=L or P, and Xaa7=S or W. Sequence ID 589: Xaa1 Xaa2 Xaa3 H Xaa4 Y, where Xaa1=K, Q, P or H, Xaa2=S, V, I or R, Xaa3=N, S, L, I or M, Xaa4=K, N or T, Sequence ID 590: AAS, and, Sequence ID 591: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 P Xaa7 Xaa8, where Xaa1=L, Q, K or H, Xaa2=L, Q, K or H, Xaa3=S, I or R, Xaa4=Y or F, Xaa5=P, N, S or T, Xaa6=P, N, S or T, Xaa7=L, I or R, Xaa8=P, N, S or T.

[0264] In the following heavy-chain-only sequence consensus / motifs, the CDR sequence is also based on the IMGT numbering scheme.

[0265] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) including HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 499, 500, and 501, respectively. Sequence ID 499: GGTFSS Xaa1 G, where Xaa1 = Y, N or D, Sequence ID 500: IIPIFGTA, and, Sequence ID 501: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 S Xaa7 Xaa8, where Xaa1=S, E or A, Xaa2=S, R or I, Xaa3=Y, A or any acidic residue (D / E), Xaa4=Y, S, F or D, Xaa5=S, C or any aromatic residue (F / Y / W), Xaa6=Y, A or any acidic residue (D / E), Xaa7=C, V or G, and Xaa8=Y or D.

[0266] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 502, 503, and 504, respectively. Sequence ID 502: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 Y Xaa7, where Xaa1=C, V or G, Xaa2=Y or S, Xaa3=P or T, Xaa4=Y, F, L or I, Xaa5=N or T, Xaa6=H, N or K, and Xaa7=Y or S, Sequence ID 503: INPYTGSA, and, Sequence number 504: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 Xaa7 Xaa8 Xaa9 Xaa10 Xaa11 Xaa12 Xaa13 Xaa14, where Xaa1=S, E or A, Xaa2=S, R, K or G, Xaa3=H, N, A or any acidic residue (D / E), Xaa4=S, D, T or A, Xaa5=P, K or T, Xaa6=E, R, V or G, Xaa7=S, H, R or L, Xaa8=H, N, P, L or Q, Xaa9=Y, S or D, Xaa10=H, N, K, I or T, Xaa11=S, G, V, C or A, Xaa12=M, R, L or I, Xaa13=H, N, G, V, Y, A or any acidic residue (D / E), and Xaa14=I, V, F, L or A.

[0267] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 505, 506, and 507, respectively. Sequence ID 505: GFT Xaa1 NSFA, where Xaa1 = C, F or V, Sequence ID 506: ISGSGGGT, and, Sequence ID 507: Xaa1 Xaa2 D Xaa3 SP Xaa4 Xaa5 Xaa6 Xaa7 SGA Xaa8 D Xaa9, where Xaa1=E or A, Xaa2=N, K, T or Q, Xaa3=S, R or L, Xaa4=Y, S or D, Xaa5=Y or any acidic residue (D / E), Xaa6=F or L, Xaa7=W, L or G, Xaa8=F, L or I, and Xaa9=Y, S or D.

[0268] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 508, 509, and 510, respectively. Sequence ID 508: Xaa1 FTF Xaa2 Xaa3 Xaa4 Xaa5, where Xaa1=C or G, Xaa2=N, S or R, Xaa3=S, N or D, Xaa4=Y, S or F, and Xaa5=S or A. Sequence ID 509: I Xaa1 GSGG Xaa2 T, where Xaa1 = S or T, and Xaa2 = S, N, T or G, Sequence ID 510: Xaa1 Xaa2 R Xaa3 Xaa4 Xaa5 F Xaa6 Xaa7 Xaa8 Xaa9 D Xaa10 Xaa11 Xaa12 Xaa13, where Xaa1=E or A, Xaa2=C or G, Xaa3=P or Q, Xaa4=Y or D, Xaa5=Y or any acidic residue (D / E), Xaa6=W, L or G, Xaa7=S, R or I, Xaa8=C, V or G, Xaa9=W, C or G, Xaa10=W, C or G, Xaa11=F, L or V, Xaa12=A or any acidic residue (D / E), and Xaa13=H, P or T.

[0269] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 511, 512, and 513, respectively. Sequence ID 511: Xaa1 Xaa2 TF Xaa3 Xaa4 Xaa5 Xaa6, where Xaa1=V or G, Xaa2=Y, F or L, Xaa3=N, S or R, Xaa4=S, N or D, Xaa5=Y, S or F, and Xaa6=S, D or A Sequence ID 512: I Xaa1 GS Xaa2 G Xaa3 T, where Xaa1=S or T, Xaa2=S or G, and Xaa3=S, N, T or G, and Sequence ID 513: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 Xaa7 Xaa8 Xaa9 Xaa10 GM Xaa11 Xaa12, where Xaa1=S, E or A, Xaa2=R, K or T, Xaa3=N or any acidic residue (D / E), Xaa4=D, T or A, Xaa5=K or T, Xaa6=E, R or G, Xaa7=H, R or L, Xaa8=H or P, Xaa9=Y or D, Xaa10=S, N, K, I, Y or T, Xaa11=Y, V or any acidic residue (D / E), and Xaa12=G, I or V.

[0270] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 514, 515, and 516, respectively. Sequence ID 514: GYTL Xaa1 Xaa2 LS, where Xaa1 = S or T, and Xaa2 = any acidic residue (D / E), Sequence ID 515: FDP Xaa1 Xaa2 Xaa3 E Xaa4, where Xaa1=E or Q, Xaa2=any acidic residue (D / E), Xaa3=N or G, and Xaa4=I or T, Sequence number 516:A Xaa1 Xaa2 Xaa3 Xaa4 Y Xaa5 Xaa6 Xaa7 Xaa8 Xaa9 Xaa10 Y Xaa11 G Xaa12 Xaa13 Xaa14 Xaa15 Xaa16 DV, where Xaa1=N, K or T, Xaa2=Y or D, Xaa3=L or V, Xaa4=W, V or G, Xaa5=Y, S or D, Xaa6=Y, S or D, Xaa7=Y or any acidic residue (D / E), Xaa8=S, R or I, Xaa9=S or R, Xaa10=V or G, Xaa11=Y, S or D, Xaa12=R or L, Xaa13=N or T, Xaa14=Y, S or D, Xaa15=V or G, and Xaa16=M or I.

[0271] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) including HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 517, 518, and 519, respectively. Sequence ID 517: GYT Xaa1 T Xaa2 Y Xaa3, where Xaa1=F or L, Xaa2=S, R or N, and Xaa3=S or G. Sequence ID 518: Xaa1 S Xaa2 Xaa3 Xaa4 G Xaa5 T, where Xaa1=I or V, Xaa2=T, F, V or A, Xaa3=Y or N, Xaa4=S or N, and Xaa5=N or D, and Sequence number 519: Xaa1 K Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 Xaa7 Xaa8 Xaa9 Xaa10 Xaa11 Xaa12 Xaa13 Xaa14 Xaa15 Xaa16 Xaa17 Xaa18 Xaa19 D Xaa20, where Xaa1=E or A, Xaa2=Y or D, Xaa3=F, L or V, Xaa4=V or G, Xaa5=Y or D, Xaa6=Y or D, Xaa7=Y, S or D, Xaa8=any acidic residue (D / E), Xaa9=S or R, Xaa10=S, R or N, Xaa11=V or G, Xaa12=Y or D, Xaa13=Y, S or D, Xaa14=R or G, Xaa15=R or L, Xaa16=N or T, Xaa17=Y or D, Xaa18=S, C or G, Xaa19=M, L or I, and Xaa20=F, I or V.

[0272] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) including HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 520, 521, and 522, respectively. Sequence ID 520: Xaa1 Xaa2 T Xaa3 Xaa4 DYXaa5, where Xaa1=R or G, Xaa2=F or L, Xaa3=C, F or V, Xaa4=N or D, and Xaa5=S or A, Sequence ID 521: I Xaa1 WNSG Xaa2 I, where Xaa1 = S or T, and Xaa2 = S, H or R, and Sequence ID 522: Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 F Xaa7 Xaa8 Xaa9 Xaa10 Xaa11 Xaa12 Xaa13 D Xaa14, where Xaa15=E or A, Xaa16=C or G, Xaa17=R or L, Xaa18=P or Q, Xaa19=Y or D, Xaa20=any acidic residue (D / E), Xaa21=W or G, Xaa22=S or R, Xaa23=C or G, Xaa24=G, L, C or any aromatic residue (F / Y / W), Xaa25=H or any acidic residue (D / E), Xaa26=W or G, Xaa27=C, F or V, and Xaa28=L or P.

[0273] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 523, 524, and 525, respectively. Sequence ID 523:RFTFDDY Xaa1, where Xaa1=S or A, Sequence ID 524: ISWNSGRI, and, Sequence ID 525: ARYG Xaa1 P Xaa2 Xaa3 Xaa4 D Xaa5, where Xaa1=Y or D, Xaa2=C, F or V, Xaa3=Y, S or D, Xaa4=C, F or L, and Xaa5=Y, S or D.

[0274] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) including HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 526, 527, and 528, respectively. Sequence ID 526: Xaa1 Xaa2 Xaa3 F Xaa4 NY Xaa5, where Xaa1=V or G, Xaa2=Y or S, Xaa3=Y or S, Xaa4=S or R, and Xaa5=W, C or L, Sequence ID 527: IDPSNSYT, and, Sequence ID 528: A Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 Xaa7 Xaa8 Xaa9 Xaa10 Xaa11 D Xaa12, where Xaa1=S or R, Xaa2=A or any acidic residue (D / E), Xaa3=R, L, I or A, Xaa4=K, T or A, Xaa5=A, T or G, Xaa6=S, C, R or G, Xaa7=R, H or N, Xaa8=Y, S or D, Xaa9=N, K, or absent, Y or T, Xaa10=C or G, Xaa11=M or R, and Xaa12=F, V or G.

[0275] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) including HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 529, 530, and 531, respectively. Sequence ID 529: GFTF Xaa1 Xaa2 Xaa3 Xaa4, where Xaa1=S or N, Xaa2=S or N, Xaa3=Y or F, and Xaa4=S or A, Sequence ID 530: I Xaa1 Xaa2 S Xaa3 Xaa4 Xaa5 T, where Xaa1=S, N or T, Xaa2=A or G, Xaa3=S or G, Xaa4=T or G, and Xaa5=S, R, T or G, and Sequence ID 531: A Xaa1 DLGY Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 GY Xaa7 Xaa8 Xaa9 Xaa10 Xaa11 G Xaa12 Xaa13 V, where Xaa1=K or T, Xaa2=Y or D, Xaa3=Y or D, Xaa4=any acidic residue (D / E), Xaa5=S, R or I, Xaa6=S or R, Xaa7=Y or S, Xaa8=E, R or G, Xaa9=H or R, Xaa10=N, K or T, Xaa11=Y, S or D, Xaa12=M or I, and Xaa13=N or D.

[0276] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 532, 533, and 534, respectively. Sequence ID 532: GFTF Xaa1 Xaa2 Xaa3 Xaa4, where Xaa1=N, S or R, Xaa2=S or D, Xaa3=Y or F, and Xaa4=S or A, Sequence ID 533: I Xaa1 Xaa2 S Xaa3 Xaa4 Xaa5 T, where Xaa1=S, N or T, Xaa2=A or G, Xaa3=S or G, Xaa4=T or G, and Xaa5=S, N, G, R or T, and Sequence ID 534: A Xaa1 RG Xaa2 Y Xaa3 Xaa4 S Xaa5 Xaa6 Xaa7 YR Xaa8 Xaa9 R Xaa10 Xaa11 Xaa12 Xaa13 Xaa14, where Xaa1=S or R, Xaa2=any acidic residue (D / E), Xaa3=Y, S or D, Xaa4=S, T or A, Xaa5=E, V or G, Xaa6=S or R, Xaa7=Y or S, Xaa8=H or P, Xaa9=H or R, Xaa10=Y or D, Xaa11=C, D or G, Xaa12=M or L, Xaa13=N or D, and Xaa14=I or V.

[0277] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 535, 536, and 537, respectively. Sequence ID 535: G Xaa1 Xaa2 FTRYG, where Xaa1 = Y or S, and Xaa2 = N or T, Sequence ID 536:ISTYSGNT, and, Sequence ID 537: Xaa1 R Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 Xaa7 Xaa8 Xaa9 Xaa10 Xaa11 Xaa12 Xaa13, where Xaa1=S or A, Xaa2=A, S or any acidic residue (D / E), Xaa3=R, L, I or A, Xaa4=S, T or A, Xaa5=S, A, T or G, Xaa6=G, R, V, D or C, Xaa7=Y, H, R or Q, Xaa8=Y, S or D, Xaa9=Y, N or absent, Xaa10=C, V or G, Xaa11=M or I, Xaa12=any acidic residue (D / E), and Xaa13=I or V.

[0278] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 538, 539, and 540, respectively. Sequence ID 538: G Xaa1 TFSTYG, where Xaa1 = F or V, Sequence ID 539: IWDDGSYK, and, Sequence ID 540: A Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 Xaa7 Xaa8 Xaa9 Xaa10 Xaa11 Xaa12 D Xaa13, where Xaa1=S, R or I, Xaa2=S or A, Xaa3=M or R, Xaa4=Y or S, Xaa5=P or T, Xaa6=M, R, L or I, Xaa7=S, D or A, Xaa8=R or L, Xaa9=R, L or I, Xaa10=W, V or G, Xaa11=W, C, L or G, Xaa12=F, L or V, and Xaa13=H, P or T.

[0279] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 541, 542, and 543, respectively. Sequence ID 541: GFTF Xaa1 Xaa2 Xaa3 A, where Xaa1=N, S or R, Xaa2=S or D, and Xaa3=Y or F, Sequence ID 542: I Xaa1 Xaa2 SG Xaa3 Xaa4 T, where Xaa1=S, N or T, Xaa2=A or G, Xaa3=T or G, and Xaa4=S, R, N or G, and Sequence ID 543: ARDS Xaa1 VAS Xaa2 GRG Xaa3 V Xaa4 H Xaa5 Xaa6 GM Xaa7 V, where Xaa1=H, N or T, Xaa2=T, K or Q, Xaa3=V or G, Xaa4=Y or D, Xaa5=Y, S or D, Xaa6=H or P, and Xaa7=N or D.

[0280] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 544, 545, and 546, respectively. Sequence ID 544: Xaa1 FTF Xaa2 Xaa3 Y Xaa4, where Xaa1=R or G, Xaa2=N or D, Xaa3=Y or D, and Xaa4=S or A. Sequence ID 545: ISWNSG Xaa1 I, where Xaa1 = S or R, Sequence ID 546: A Xaa1 Xaa2 R Xaa3 Xaa4 D Xaa5, where Xaa1=R or L, Xaa2=S, V or G, Xaa3=T, H, N or Q, Xaa4=R, L or V, and Xaa5=S, K, Y, Q, T or A.

[0281] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 547, 548, and 549, respectively. Sequence ID 547: GYTFTNYY, Sequence ID 548: INPYTGSA, and, Sequence ID 549: ARDP Xaa1 G Xaa2 VNH Xaa3 Y Xaa4 Xaa5 D Xaa6, where Xaa1=C, F, L or V, Xaa2=V or G, Xaa3=F or L, Xaa4=Y, S or D, Xaa5=M, R, L or I, and Xaa6=V or G.

[0282] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) including HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 550, 551, and 552, respectively. Sequence ID 550: GGSFSGYY, Sequence ID 551: INHSGST, and, Sequence ID 552: Xaa1 Xaa2 P Xaa3 Xaa4 Xaa5 Xaa6 Xaa7 ES Xaa8 Xaa9 Xaa10 Xaa11 Xaa12 D Xaa13, where Xaa1=E or A, Xaa2=M or R, Xaa3=Y, S or D, Xaa4=H, N or T, Xaa5=S or R, Xaa6=S or A, Xaa7=W, C or L, Xaa8=Y, S or D, Xaa9=Y, S or D, Xaa10=Y, S or D, Xaa11=V or G, Xaa12=M, R or L, and Xaa13=F or V.

[0283] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) including HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 553, 554, and 555, respectively. Sequence ID 543: GYTFTNYY, Sequence ID 554: INPYTGSA, and, Sequence ID 555: AR Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 Xaa7 Xaa8 Xaa9 Xaa10 Xaa11, where Xaa1=S, F, V or A, Xaa2=R, L or I, Xaa3=G or A, Xaa4=S, T or A, Xaa5=C, I or G, Xaa6=R or L, Xaa7=Y, S or D, Xaa8=C, D, V or G, Xaa9=M, R or I, Xaa10=N or D, and Xaa11=I or V.

[0284] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 556, 557, and 558, respectively. Sequence ID 556: GFT Xaa1 NSFA, where Xaa1 = F or V, Sequence ID 557: ISGSGGGT, and, Sequence ID 558: A Xaa1 Xaa2 Xaa3 Xaa4 Xaa5 Xaa6 Xaa7, where Xaa1=R or L, Xaa2=S, W or G, Xaa3=R or L, Xaa4=T, H, N or Q, Xaa5=G, R, I, V or L, Xaa6=any acidic residue (D / E), and Xaa7=S, K or T.

[0285] In some embodiments, the anti-IGSF8 antibody of the present invention comprises a monoclonal antibody or antigen-binding site / fragment thereof that is specific to IGSF8 (e.g., specific to the Ig-V set domain of IGSF8 or the D1 domain of ECD), wherein the monoclonal antibody comprises a heavy chain variable region (HCVR) comprising HCVR CDR1, CDR2, and CDR3 of SEQ ID NOs. 559, 560, and 561, respectively. Sequence ID 559: G Xaa1 TFTRY Xaa2, where Xaa1 = Y or S, & Xaa2 = C or G, Sequence ID 560:ISTYSGNT, and, Sequence ID 561: A Xaa1 G Xaa2 Xaa3 P Xaa4 R Xaa5 H Xaa6 Xaa7 Xaa8 Xaa9 Xaa10, where Xaa1=R or K, Xaa2=W, V or G, Xaa3=R or L, Xaa4=Y, S or D, Xaa5=W, V or G, Xaa6=Y or D, Xaa7=C, D or G, Xaa8=M or I, Xaa9=N or any acidic residue (D / E), and Xaa10=F, I or V.

[0286] In some embodiments, the present invention provides an anti-IGSF8 monoclonal antibody or antigen-binding fragment specific to IGSF8, wherein the monoclonal antibody comprises (1) a heavy chain variable region (HCVR) containing an HCVR CDR1-CDR3 sequence which is at least 95% (e.g., 100%) identical to any one of the antibody C1-C39, e.g., C30-C39, or which has up to 1, 2, 3, 4, 5, 6, 7, 8, or 9 substitutions therein; and (2) a light chain variable region (LCVR) containing an LCVR CDR1-CDR3 sequence which is at least 95% (e.g., 100%) identical to any one of the antibody C1-C39, e.g., C30-C39, or which has up to 1, 2, 3, 4, 5, 6, 7, 8, or 9 substitutions therein. In certain embodiments, the anti-IGSF8 monoclonal antibody or its antigen-binding fragment has one of the antibody C1-C39, for example, one of C30-C39, as HCVR CDR1-CDR3 and LCVR CDR1-CDR3.

[0287] In some embodiments, the monoclonal antibody or its antigen-binding fragment comprises (a) an HCVR sequence that is at least 95% (e.g., 100%) identical to any one HCVR sequence of antibody C1-C39, e.g., C30-C39; and / or (b) an LCVR sequence that is at least 95% (e.g., 100%) identical to any one LCVR sequence of antibody C1-C39, e.g., C30-C39. In certain embodiments, the anti-IGSF8 monoclonal antibody or its antigen-binding fragment has an HCVR and an LCVR of one of antibody C1-C39, e.g., any one of C30-C39.

[0288] In some embodiments, the present invention provides an anti-IGSF8 monoclonal antibody or an antigen-binding fragment thereof that is specific to IGSF8, comprising: (1) a heavy chain variable region (HCVR) comprising an HCVR CDR1-CDR3 sequence having up to 1, 2, or 3 residue substitutions compared to each of the antibody C1-C39, e.g., C30-C39; and (2) a light chain variable region (LCVR) comprising an LCVR CDR1-CDR3 sequence having up to 1, 2, or 3 residue substitutions compared to each of the antibody C1-C39, e.g., C30-C39. In some embodiments, if the CDR has only 5, 4, or 3 residues, substitutions other than conserved substitutions are not permitted (e.g., a CDR having 5, 4, or 3 or fewer residues may have up to 1 or 2 conserved substitutions).

[0289] High affinity IGSF8 antibody based on comprehensive CDR region mutagenesis analysis To determine the relative importance of each CDR region residue, as well as the framework region residues surrounding the CDR region, two specific high-affinity antibodies were selected for further CDR region sequence analysis to identify (or identify as unimportant) key residues crucial for IGSF8 binding. Specifically, all possible mutants were generated by individually substituting the existing residues in each of the two lead antibodies with 19 other amino acids, and the effects of such substitutions were evaluated. Figures 29–36 summarize the results for each substitution. Based on this study, consensus sequences were constructed representing all acceptable substitutions (e.g., those that substantially do not affect antigen binding) as well as preferred substitutions (e.g., those that increase antigen binding compared to the original sequence), and these are presented herein.

[0290] Accordingly, the disclosure of the present invention includes amino acid consensus sequences for CDR region sequences (in some cases surrounding framework region sequences based on the IMGT numbering scheme) that indicate specific amino acids (indicated using the variable "X" or "Xaa") that may be modified or substituted in the antibody amino acid sequence, such as those listed in Tables A1 and A2. Unless expressly indicated, all antibodies and CDR sequences are annotated by the IMGT numbering scheme.

[0291] Related CDR sequences that may appear in the same VH and / or VL sequence of an antibody are grouped together in the same column. For example, the antibody of the present invention may contain one of VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3, where VH CDR1-VH CDR3 and VL CDR1-VL CDR3 are represented by SEQ ID NOs. 714, 715, 716, 717, 718, and 719, respectively.

[0292] Furthermore, the amino acids at each Xi position (where i = 1, 2, 3, ~) may be a selected subset of amino acids, as identified in each consensus sequence. It is expected that one or more of the enumerated specific amino acids at each Xi position may be acceptable values ​​at that Xi position. For example, in Sequence ID No. 714, X2 may be any residue, such as A, C, D, E, F, G, H, K, M, N, P, Q, R, T, or W. In some embodiments, X2 may be A or C, F or G; M, N, or Q, etc.

[0293] Unless otherwise explicitly stated, all antibodies and CDR sequences are annotated using the IMGT numbering scheme.

[0294] [Table 1-1]

[0295] [Table 1-2]

[0296] [Table 1-3]

[0297] [Table 1-4]

[0298] [Table 1-5]

[0299] [Table 1-6]

[0300] [Table 1-7]

[0301] [Table 1-8]

[0302] [Table 1-9]

[0303] [Table 1-10]

[0304] [Table 1-11]

[0305] [Table 1-12]

[0306] In certain embodiments, in any of the definitions of Xi residues listed in Table A1, the residue after “for example” has an enhanced bond at the same position compared to the original residue. Table A2 provides antibody consensus sequences having such enhanced bonds.

[0307] [Table 2-1]

[0308] [Table 2-2]

[0309] [Table 2-3]

[0310] [Table 2-4]

[0311] [Table 2-5]

[0312] [Table 2-6]

[0313] [Table 2-7]

[0314] [Table 2-8]

[0315] Therefore, in certain embodiments, the anti-IGSF8 antibody or its antigen-binding fragment comprises VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3, each containing, essentially consisting of, or comprising the amino acid sequences of SEQ ID NOs. 714, 715, 716, 717, 718, and 719, respectively.

[0316] In certain embodiments, the anti-IGSF8 antibody or its antigen-binding fragments include VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3, each comprising, essentially consisting of, or comprising the amino acid sequences of SEQ ID NOs. 720, 721, 722, 723, 724, and 725, respectively.

[0317] In certain embodiments, the anti-IGSF8 antibody or its antigen-binding fragments include VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3, each comprising, essentially consisting of, or comprising the amino acid sequences of SEQ ID NOs. 754, 755, 756, 757, 758, and 759, respectively.

[0318] In certain embodiments, the anti-IGSF8 antibody or its antigen-binding fragments include VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3, each comprising, essentially consisting of, or comprising the amino acid sequences of SEQ ID NOs. 760, 761, 762, 763, 764, and 765, respectively.

[0319] In certain embodiments, the anti-IGSF8 antibody or its antigen-binding fragment comprises VH, which includes, essentially consists of, or comprises the amino acid sequences of SEQ ID NOs. 734, 735, and 736, and VL, which includes, essentially consists of, or comprises the amino acid sequences of SEQ ID NOs. 737, 738, and 739.

[0320] In certain embodiments, the anti-IGSF8 antibody or its antigen-binding fragment comprises VH, which includes, essentially consists of, or comprises the amino acid sequences of SEQ ID NOs. 740, 741, and 742, and VL, which includes, essentially consists of, or comprises the amino acid sequences of SEQ ID NOs. 743, 744, and 745.

[0321] In certain embodiments, the anti-IGSF8 antibody or its antigen-binding fragment comprises VH, which includes, essentially consists of, or comprises the amino acid sequences of SEQ ID NOs. 774, 775, and 776, and VL, which includes, essentially consists of, or comprises the amino acid sequences of SEQ ID NOs. 777, 778, and 779.

[0322] In certain embodiments, the anti-IGSF8 antibody or its antigen-binding fragment comprises VH, which includes, essentially consists of, or comprises the amino acid sequences of SEQ ID NOs. 780, 781, and 782, and VL, which includes, essentially consists of, or comprises the amino acid sequences of SEQ ID NOs. 783, 784, and 785.

[0323] For example, in some embodiments, the anti-IGSF8 antibody or its antigen-binding fragment is (i) VH CDR1 containing, essentially consisting of, or comprising the amino acid sequence X1-X2-X3-X4-X5-X6-X7-X8 (SEQ ID NO: 714) (wherein, X1 is A, E, F, G, H, I, K, L, M, N, P, Q, R, T, V, W, or Y. X2 is A, C, D, E, F, G, H, K, M, N, P, Q, R, T, or W. X3 is A, C, D, E, F, G, H, K, L, M, P, Q, R, T, V, W, or Y. X4 is A, C, D, E, F, G, H, K, M, N, P, Q, R, T, or W. X5 is A, C, D, E, G, H, I, K, L, M, N, Q, R, S, V, or W. X6 is C, D, E, F, G, H, I, L, N, P, Q, T, V, W, or Y. X7 is A, D, E, F, G, I, K, L, M, P, Q, R, S, T, V, W, or Y. X8 is E, F, G, H, I, K, L, M, N, P, Q, R, T, W, or Y; (ii) VH CDR2 containing, essentially consisting of, or comprising the amino acid sequence X3-X4-X5-X6-X7-X8-X9-X10 (SEQ ID NO: 715) (wherein, X3 is A, C, D, E, G, H, I, K, L, M, P, Q, R, W, or Y. X4 is A, D, E, F, H, I, K, M, N, P, Q, R, T, V, W, or Y, for example, R. X5 is C or D, X6 is A, D, E, F, or G, for example, G, E, or A, most preferably G. X7 is D, E, F, G, H, I, K, L, M, N, P, Q, T, W, or Y. X8 is C, F, H, K, P, R, S, T, W, or Y, for example, K or R, most preferably K. X9 is A, D, E, F, G, I, K, L, M, P, Q, R, T, V, W, or Y. X10 is A, C, D, F, G, H, I, K, L, P, Q, S, V, W, or Y; (iii) VH CDR3 containing, essentially consisting of, or comprising the amino acid sequence X1-X2-X3-X4-X5-X6-X7-X8-X9-X10-X11-X12-X13 (sequence number 716) (wherein, X1 is A, C, D, F, G, H, I, K, L, M, N, Q, R, W, or Y. X2 is A, C, D, E, F, H, L, M, N, P, Q, R, V, W, or Y. X3 is C, D, F, I, or Q. X4 is E, F, G, H, I, K, L, M, N, P, or Q. X5 is A, D, E, F, H, I, K, L, M, P, Q, S, T, V, W, or Y. X6 is A, E, F, G, H, I, K, L, M, N, P, Q, R, T, W, or Y. X7 is A, D, E, F, H, I, M, N, P, Q, S, T, V, W, or Y, for example, Y. X8 is A, C, D, F, G, H, I, K, L, M, N, P, Q, S, T, W, or Y. X9 is A, E, G, I, K, L, M, P, Q, R, T, V, W, or Y. X10 is A, C, E, F, H, I, K, L, M, N, Q, or R. X11 is D, F, G, H, M, N, P, R, T, or W. X12 is C, D, F, K, L, M, P, Q, R, or W, for example, R or K. X13 is G, H, I, K, M, P, Q, R, W, or Y; (iv) VL CDR1 containing, essentially consisting of, or comprising the amino acid sequence X4-X5-X6-X7-X8-X9 (SEQ ID NO: 717) (wherein, X4 is A, C, D, E, F, G, I, K, L, M, N, Q, S, T, V, W, or Y. X5 is A, C, D, E, F, H, I, K, L, M, N, P, Q, R, T, V, or W. X6 is A, C, D, E, F, G, H, I, K, M, P, Q, R, V, W, or Y. X7 is C, D, E, F, G, K, L, M, R, S, T, V, W, or Y, for example, E, G, K, M, T, V, or W. X8 is C, D, E, F, G, H, I, L, M, P, Q, S, T, V, W, or Y, for example, D, F, G, L, M, P, Q, S, T, V, W, or Y. X9 is A, C, F, G, H, I, Q, S, T, W, or Y, for example, A, C, G, Q, S, T, or W, most preferably W); (v) VL CDR2 containing, essentially consisting of, or comprising amino acid sequence X6-X7-X8 (SEQ ID NO: 718) (in the formula, X6 is A, C, D, F, G, H, N, R, or S, for example, A, G, H, N, R, or S, most preferably G. X7 is A, C, D, I, K, S, or T, for example, D, S, or T, most preferably S. X8 is A, C, D, E, F, H, I, N, P, S, T, V, or W, for example, A, D, E, F, H, N, P, T, V, or W, most preferably P. (vi) VL CDR3 containing, essentially consisting of, or comprising the amino acid sequence X1-X2-X3-X4-X5-X6-X7-X8-X9 (SEQ ID NO: 719) (wherein, X1 is A, C, D, E, F, G, I, M, N, P, Q, S, T, V, W, or Y. X2 is A, C, D, E, F, G, I, M, N, P, Q, S, T, V, W, or Y. X3 is A, C, D, E, G, I, K, L, M, N, P, Q, R, T, V, W, or Y. X4 is D, E, F, P, Q, or Y, for example, E, Q, or Y. X5 is G, K, L, M, N, P, Q, R, or S, for example, G, R, or K. X6 is C, D, E, F, H, I, L, M, N, P, Q, S, T, V, or Y, for example, D, E, L, M, N, Q, S, T, or V. X7 is A, C, D, E, F, G, I, K, L, M, N, P, Q, R, V, W, or Y. X8 is A, E, F, G, I, K, M, N, P, Q, R, T, V, W, or Y. X9 is C, D, E, F, G, H, I, K, L, M, N, Q, R, T, V, W, or Y. Includes.

[0324] As another example, in some embodiments, the anti-IGSF8 antibody or its antigen-binding fragment is (i) VH CDR1 containing, essentially consisting of, or comprising the amino acid sequence X1-X2-X3-X4-X5-X6-X7-X8 (SEQ ID NO: 720) (wherein, X1 is A, C, D, E, F, G, H, I, K, L, M, N, P, Q, R, S, T, V, W, or Y, for example, R. X2 is A, C, D, E, F, G, H, K, L, M, N, P, Q, R, S, T, V, or W, for example, G. X3 is A, C, D, E, F, G, H, I, K, L, M, N, P, Q, R, T, V, W, or Y. X4 is A, C, D, E, F, G, H, I, K, M, N, P, Q, R, S, T, V, W, or Y. X5 is I, K, L, M, P, Q, V, W, or Y, for example, K. X6 is F, G, H, I, K, L, M, P, Q, T, V, W, or Y. X7 is A, C, D, E, F, G, H, I, K, M, N, P, Q, R, S, T, V, W, or Y, for example, F, S, or N, more preferably F. X8 is A, C, D, E, F, H, K, L, M, N, P, Q, R, T, or V; (ii) VH CDR2 containing, essentially consisting of, or comprising the amino acid sequence X2-X3-X4-X5-X6-X7-X8-X9 (Sequence ID 721) (wherein, X2 is A, C, D, E, G, H, I, K, L, M, N, P, Q, R, S, T, V, W, or Y. X3 is A, C, E, F, G, H, I, K, L, M, P, Q, R, S, V, or Y. X4 is C, D, E, F, G, H, I, K, L, M, N, Q, R, S, or V. X5 is A, C, F, H, K, L, M, P, Q, R, S, T, V, or W, for example, M. X6 is A, C, E, F, G, H, I, K, L, M, P, Q, R, V, or W, for example, F. X7 is A, C, D, E, F, G, H, I, K, L, M, N, P, Q, R, T, V, W, or Y. X8 is A, C, F, G, I, K, L, M, N, P, Q, R, S, T, V, W, or Y, for example, G, N, R, S, or T, more preferably G or S. X9 is C, D, E, F, G, H, K, L, M, N, P, Q, S, T, V, W, or Y; (iii) VH CDR3 containing, essentially consisting of, or comprising the amino acid sequence X1-X2-X3-X4-X5-X6-X7-X8-X9-X10-X11-X12-X13-X14-X15 (sequence number 722) (wherein, X1 is A, C, D, E, F, G, H, I, K, L, M, N, P, Q, R, S, T, V, W, or Y. X2 is F, G, H, I, or T. X3 is A, C, D, F, G, H, I, K, L, M, N, P, Q, R, S, T, V, W, or Y. X4 is D, E, F, H, N, Q, R, S, T, V, W, or Y, for example, D. X5 is A, H, I, L, M, N, Q, or Y. X6 is A, C, D, F, G, H, K, M, N, P, Q, R, S, T, V, or Y. X7 is A, C, E, F, H, K, M, N, P, Q, S, T, W, or Y. X8 is A, C, D, E, F, G, H, I, K, L, M, N, P, Q, S, T, V, or W. X9 is A, C, D, E, F, H, I, K, L, N, Q, R, S, V, W, or Y. X10 is A, C, D, E, F, H, I, K, L, M, N, P, Q, R, S, V, W, or Y. X11 is A, C, E, F, H, I, K, L, M, N, P, Q, S, T, V, W, or Y. X12 is F, H, I, K, N, P, Q, R, V, W, or Y, for example, F or Y. X13 is A, C, D, E, F, G, H, I, K, L, N, P, Q, R, S, T, V, W, or Y. X14 is D, F, G, H, P, Q, or T, for example, T. X15 is D, E, F, G, I, K, L, N, P, Q, R, S, or T; (iv) VL CDR1 containing, essentially consisting of, or comprising the amino acid sequence X4-X5-X6-X7-X8-X9 (SEQ ID NO: 723) (wherein, X4 is A, C, D, E, F, G, I, K, M, N, R, S, T, V, W, or Y, for example, E. X5 is C, D, E, H, K, L, M, Q, T, W, or Y, for example, D. X6 is A, C, D, E, F, G, H, K, M, N, P, Q, R, T, V, W, or Y. X7 is C, E, G, I, L, M, P, Q, V, W, or Y. X8 is C, M, P, Q, T, or W, for example, P. X9 is A, C, E, F, G, I, K, L, M, N, P, Q, R, T, V, or Y, for example, Y); (v) VL CDR2 containing, essentially consisting of, or comprising amino acid sequence X6-X7-X8 (SEQ ID NO: 724) (in the formula, X6 is C, H, I, L, M, N, P, Q, W, or Y, for example, H or Q. X7 is C, D, E, F, G, H, I, K, L, M, N, P, Q, R, S, T, V, W, or Y, for example, S, T, or V, more preferably S or T. X8 is C, D, E, G, H, I, K, L, M, P, Q, R, S, W, or Y); and (vi) VL CDR3 containing, essentially consisting of, or comprising the amino acid sequence X1-X2-X3-X4-X5-X6-X7-X8-X9 (SEQ ID NO: 725) (wherein, X1 is C, D, F, G, I, K, M, N, P, Q, S, T, V, W, or Y. X2 is A, C, D, F, G, I, L, M, N, P, Q, R, S, T, V, or W. X3 is C, E, G, K, M, P, S, V, or W. X4 is C, H, L, M, P, Q, R, V, or W, for example, P. X5 is C, D, E, F, L, M, P, V, or W, for example, F. X6 is A, C, E, G, H, K, M, N, P, Q, R, V, or W, for example, A, N, P, R, or W. X7 is A, C, D, E, G, H, I, K, M, N, P, R, S, T, V, W, or Y. X8 is A, C, D, E, G, K, M, N, P, Q, R, S, or W, for example, D, P, S, or W. X9 is C, D, E, F, G, H, K, L, M, Q, R, T, V, W, or Y. Includes.

[0325] In some embodiments, the anti-IGSF8 antibody of the present invention or its antigen-binding fragment (e.g., having the consensus CDR sequence described above) comprises at least one, two, or three (e.g., all three) corresponding VH CDRs of any one of the antibodies listed in Tables D and G.

[0326] For example, in one embodiment, the antibody of the present invention may have a VH CDR1 sequence identical to the VH CDR1 sequence of any one of the antibodies listed in Table D. In one embodiment, the antibody of the present invention may have a VH CDR2 sequence identical to the VH CDR2 sequence of any one of the antibodies listed in Table D. In one embodiment, the antibody of the present invention may have a VH CDR3 sequence identical to the VH CDR3 sequence of any one of the antibodies listed in Table D.

[0327] In another embodiment, the antibody of the present invention may have a VH CDR1 sequence identical to the VH CDR1 sequence of any one of the first antibodies listed in Table D; and a VH CDR2 sequence identical to the VH CDR2 sequence of any one of the second antibodies listed in Table D, wherein the first and second antibodies are identical or different. In another embodiment, the antibody of the present invention may have a VH CDR1 sequence identical to the VH CDR2 sequence of any one of the first antibodies listed in Table D; and a VH CDR3 sequence identical to the VH CDR3 sequence of any one of the second antibodies listed in Table D, wherein the first and second antibodies are identical or different. In another embodiment, the antibody of the present invention may have a VH CDR2 sequence identical to the VH CDR2 sequence of any one of the first antibodies listed in Table D; and a VH CDR3 sequence identical to the VH CDR3 sequence of any one of the second antibodies listed in Table D, wherein the first and second antibodies are identical or different.

[0328] In yet another embodiment, the antibody of the present invention may have a VH CDR1 sequence identical to the VH CDR1 sequence of any one of the first antibodies listed in Table D; a VH CDR2 sequence identical to the VH CDR2 sequence of any one of the second antibodies listed in Table D; and a VH CDR3 sequence identical to the VH CDR3 sequence of any one of the third antibodies listed in Table D, wherein the first, second, and third antibodies may be identical or different (for example, two may be derived from the same antibody and one from a different antibody, or all three may be derived from different antibodies).

[0329] In some embodiments, the anti-IGSF8 antibody of the present invention or its antigen-binding fragment (e.g., having the consensus CDR sequence described above) comprises at least one, two, or three (e.g., all three) corresponding VH CDRs of any one of the antibodies listed in Table G.

[0330] For example, in one embodiment, the antibody of the present invention may have a VH CDR1 sequence identical to the VH CDR1 sequence of any one of the antibodies listed in Table G. In one embodiment, the antibody of the present invention may have a VH CDR2 sequence identical to the VH CDR2 sequence of any one of the antibodies listed in Table G. In one embodiment, the antibody of the present invention may have a VH CDR3 sequence identical to the VH CDR3 sequence of any one of the antibodies listed in Table G.

[0331] In another embodiment, the antibody of the present invention may have a VH CDR1 sequence identical to the VH CDR1 sequence of any one of the first antibodies listed in Table G; and a VH CDR2 sequence identical to the VH CDR2 sequence of any one of the second antibodies listed in Table G, wherein the first and second antibodies are identical or different. In another embodiment, the antibody of the present invention may have a VH CDR1 sequence identical to the VH CDR2 sequence of any one of the first antibodies listed in Table G; and a VH CDR3 sequence identical to the VH CDR3 sequence of any one of the second antibodies listed in Table G, wherein the first and second antibodies are identical or different. In another embodiment, the antibody of the present invention may have a VH CDR2 sequence identical to the VH CDR2 sequence of any one of the first antibodies listed in Table G; and a VH CDR3 sequence identical to the VH CDR3 sequence of any one of the second antibodies listed in Table G, wherein the first and second antibodies may be identical or different.

[0332] In yet another embodiment, the antibody of the present invention may have a VH CDR1 sequence identical to the VH CDR1 sequence of any one of the first antibodies listed in Table G; a VH CDR2 sequence identical to the VH CDR2 sequence of any one of the second antibodies listed in Table G; and a VH CDR3 sequence identical to the VH CDR3 sequence of any one of the third antibodies listed in Table G, wherein the first, second, and third antibodies may be identical or different (for example, two may be derived from the same antibody and one from a different antibody, or all three may be derived from different antibodies).

[0333] In some embodiments, the VH CDR1, VH CDR2, and / or VH CDR3 of the anti-IGSF8 antibody of the present invention or its antigen-binding fragment (e.g., having the consensus CDR sequence described above) have one, two, three, four, five, or more changes, e.g., amino acid substitutions, insertions, or deletions, compared to the amino acid sequences of the corresponding VH CDR1, VH CDR2, and / or VH CDR3 of any one of the antibodies listed in Table D.

[0334] In some embodiments, the VH CDR1, VH CDR2, and / or VH CDR3 of the anti-IGSF8 antibody of the present invention or its antigen-binding fragment (e.g., having the consensus CDR sequence described above) have one, two, three, four, five, or more changes, e.g., amino acid substitutions, insertions, or deletions, compared to the amino acid sequences of the corresponding VH CDR1, VH CDR2, and / or VH CDR3 of any one of the antibodies listed in Table G.

[0335] In some embodiments, the anti-IGSF8 antibody of the present invention or its antigen-binding fragment (e.g., having the consensus CDR sequence described above) comprises at least one, two, or three (e.g., all three) corresponding VL CDRs of any one of the antibodies listed in Table D.

[0336] For example, in one embodiment, the antibody of the present invention may have a VL CDR1 sequence identical to the VL CDR1 sequence of any one of the antibodies listed in Table D. In one embodiment, the antibody of the present invention may have a VL CDR2 sequence identical to the VL CDR2 sequence of any one of the antibodies listed in Table D. In one embodiment, the antibody of the present invention may have a VL CDR3 sequence identical to the VL CDR3 sequence of any one of the antibodies listed in Table D.

[0337] In another embodiment, the antibody of the present invention may have a VL CDR1 sequence identical to the VL CDR1 sequence of any one of the first antibodies listed in Table D; and a VL CDR2 sequence identical to the VL CDR2 sequence of any one of the second antibodies listed in Table D, wherein the first and second antibodies are identical or different. In another embodiment, the antibody of the present invention may have a VL CDR1 sequence identical to the VL CDR2 sequence of any one of the first antibodies listed in Table D; and a VL CDR3 sequence identical to the VL CDR3 sequence of any one of the second antibodies listed in Table D, wherein the first and second antibodies are identical or different. In another embodiment, the antibody of the present invention may have a VL CDR2 sequence identical to the VL CDR2 sequence of any one of the first antibodies listed in Table D; and a VL CDR3 sequence identical to the VL CDR3 sequence of any one of the second antibodies listed in Table D, wherein the first and second antibodies are identical or different.

[0338] In yet another embodiment, the antibody of the present invention may have a VL CDR1 sequence identical to the VL CDR1 sequence of any one of the first antibodies listed in Table D; a VL CDR2 sequence identical to the VL CDR2 sequence of any one of the second antibodies listed in Table D; and a VL CDR3 sequence identical to the VL CDR3 sequence of any one of the third antibodies listed in Table D, wherein the first, second, and third antibodies may be identical or different (for example, two may be derived from the same antibody and one from a different antibody, or all three may be derived from different antibodies).

[0339] In some embodiments, the anti-IGSF8 antibody of the present invention or its antigen-binding fragment (e.g., having the consensus CDR sequence described above) comprises at least one, two, or three (e.g., all three) corresponding VL CDRs of any one of the antibodies listed in Table G.

[0340] For example, in one embodiment, the antibody of the present invention may have a VL CDR1 sequence identical to that of any one of the antibodies listed in Table G. In one embodiment, the antibody of the present invention may have a VL CDR2 sequence identical to that of any one of the antibodies listed in Table G. In one embodiment, the antibody of the present invention may have a VL CDR3 sequence identical to that of any one of the antibodies listed in Table G.

[0341] In another embodiment, the antibody of the present invention may have a VL CDR1 sequence identical to the VL CDR1 sequence of any one of the first antibodies listed in Table G; and a VL CDR2 sequence identical to the VL CDR2 sequence of any one of the second antibodies listed in Table G, wherein the first and second antibodies are identical or different. In another embodiment, the antibody of the present invention may have a VL CDR1 sequence identical to the VL CDR2 sequence of any one of the first antibodies listed in Table G; and a VL CDR3 sequence identical to the VL CDR3 sequence of any one of the second antibodies listed in Table G, wherein the first and second antibodies are identical or different. In another embodiment, the antibody of the present invention may have a VL CDR2 sequence identical to the VL CDR2 sequence of any one of the first antibodies listed in Table G; and a VL CDR3 sequence identical to the VL CDR3 sequence of any one of the second antibodies listed in Table G, wherein the first and second antibodies may be identical or different.

[0342] In yet another embodiment, the antibody of the present invention may have a VL CDR1 sequence identical to the VL CDR1 sequence of any one of the first antibodies listed in Table G; a VL CDR2 sequence identical to the VL CDR2 sequence of any one of the second antibodies listed in Table G; and a VL CDR3 sequence identical to the VL CDR3 sequence of any one of the third antibodies listed in Table G, wherein the first, second, and third antibodies may be identical or different (for example, two may be derived from the same antibody and one from a different antibody, or all three may be derived from different antibodies).

[0343] In some embodiments, the VL CDR1, VL CDR2, and / or VL CDR3 of the anti-IGSF8 antibody of the present invention or its antigen-binding fragment (e.g., having the consensus CDR sequence described above) have one, two, three, four, five, or more changes, e.g., amino acid substitutions, insertions, or deletions, compared to the amino acid sequences of the corresponding VL CDR1, VL CDR2, and / or VL CDR3 of any one of the antibodies listed in Table D.

[0344] In some embodiments, the VL CDR1, VL CDR2, and / or VL CDR3 of the anti-IGSF8 antibody of the present invention or its antigen-binding fragment (e.g., having the consensus CDR sequence described above) have one, two, three, four, five, or more changes, e.g., amino acid substitutions, insertions, or deletions, compared to the amino acid sequences of the corresponding VL CDR1, VL CDR2, and / or VL CDR3 of any one of the antibodies listed in Table G.

[0345] In any of the following embodiments relating to a specific antibody defined by six CDR region sequences, it is explicitly expected that VH CDR1, VH CDR2, and VH CDR3 contain, essentially consist of, or comprise the amino acid sequences of their respective enumerated SEQ ID NOs, and VL CDR1, VL CDR2, and VL CDR3 contain, essentially consist of, or comprise the amino acid sequences of their respective enumerated SEQ ID NOs; however, for simplicity, only the following description uses the transitional clause “contains”.

[0346] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 611, 623, and 631, respectively.

[0347] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 612, 623, and 631, respectively.

[0348] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 611, 624, and 631, respectively.

[0349] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 611, 625, and 631, respectively.

[0350] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 613, 623, and 631, respectively.

[0351] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 614, 623, and 631, respectively.

[0352] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 615, 623, and 631, respectively.

[0353] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 616, 623, and 631, respectively.

[0354] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 611, 626, and 631, respectively.

[0355] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 611, 627, and 631, respectively.

[0356] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 617, 623, and 631, respectively.

[0357] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 611, 628, and 631, respectively.

[0358] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 611, 629, and 631, respectively.

[0359] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 611, 630, and 631, respectively.

[0360] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 618, 623, and 631, respectively.

[0361] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 614, 625, and 631, respectively.

[0362] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 614, 629, and 631, respectively.

[0363] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 614, 625, and 631, respectively.

[0364] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 619, 629, and 631, respectively.

[0365] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 615, 625, and 631, respectively.

[0366] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 614, 625, and 631, respectively.

[0367] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 620, 625, and 631, respectively.

[0368] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 614, 625, and 631, respectively.

[0369] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 621, 635, and 631, respectively.

[0370] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 620, 625, and 631, respectively.

[0371] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 619, 625, and 631, respectively.

[0372] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 622, 625, and 631, respectively.

[0373] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 615, 625, and 631, respectively.

[0374] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 614, 629, and 631, respectively.

[0375] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 602, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 614, 628, and 631, respectively.

[0376] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 603, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 614, 624, and 631, respectively.

[0377] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 604, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 614, 625, and 631, respectively.

[0378] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 601, 603, and 605, respectively, as well as VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 614, 625, and 631, respectively.

[0379] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3 containing the amino acid sequences of SEQ ID NOs. 643, 644, and 646, respectively, and VL CDR1, VL CDR2, and VL CDR3 containing the amino acid sequences of SEQ ID NOs. 652, 653, and 655, respectively.

[0380] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3, each containing the amino acid sequences of SEQ ID NOs. 643, 644, and 646, respectively, as well as VL CDR1, VL CDR2, and VL CDR3, each containing the amino acid sequences of SEQ ID NOs. 652, 654, and 655, respectively.

[0381] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3, each containing the amino acid sequences of SEQ ID NOs. 643, 645, and 646, respectively, as well as VL CDR1, VL CDR2, and VL CDR3, each containing the amino acid sequences of SEQ ID NOs. 652, 653, and 655, respectively.

[0382] In some embodiments, the anti-IGSF8 antibody includes VH CDR1, VH CDR2, and VH CDR3, each containing the amino acid sequences of SEQ ID NOs. 643, 645, and 646, respectively, as well as VL CDR1, VL CDR2, and VL CDR3, each containing the amino acid sequences of SEQ ID NOs. 652, 654, and 655, respectively.

[0383] Framework domain (FR) The anti-IGSF antibody or its antigen-binding fragment according to the disclosure of the present invention can be prepared using either the framework region (FR) of the amino acid sequence described in Table D and / or Table G, or a sequence that is substantially identical to the amino acid sequence of the FR described in Table D and / or Table G (for example, having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0384] In some embodiments, the anti-IGSF8 antibody or its antigen-binding fragment has a heavy chain variable region (VH) containing VH FR1, VH FR2, VH FR3 and / or VH FR4, which contain one, two, three, or all (i.e., four) of the corresponding heavy chain framework region of any one of the antibodies listed in Table D or G, or VH FR1, VH FR2, VH FR2, VH FR2, VH FR3 and / or VH FR4, or sequences that are substantially identical (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99%) to the corresponding VH FR amino acid sequence of any one of the antibodies listed in Table D or G.

[0385] In some embodiments, the anti-IGSF8 antibody contains an amino acid sequence that is substantially identical to the VH FR1 of SEQ ID NO: 606, 647, or 648 (for example, having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity) of SEQ ID NO: 606, 647, or 648.

[0386] In some embodiments, the anti-IGSF8 antibody contains the VH FR2 of SEQ ID NO: 607, 649, or 650, or an amino acid sequence substantially identical to SEQ ID NO: 607, 649, or 650 (for example, having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0387] In some embodiments, the anti-IGSF8 antibody contains the VH FR3 of SEQ ID NO: 608 or 651, or an amino acid sequence substantially identical to SEQ ID NO: 608 or 651 (for example, having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0388] In some embodiments, the anti-IGSF8 antibody contains the VH FR4 of SEQ ID NO: 609 or 610, or an amino acid sequence substantially identical to SEQ ID NO: 609 or 610 (for example, having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0389] In some embodiments, the anti-IGSF8 antibody has a VH comprising one, two, three, or all of VH FR1, VH FR2, VH FR3, and / or VH FR4, each containing the amino acid sequence of SEQ ID NOs. 606, 607, 608, and / or 609, or an amino acid sequence substantially identical to SEQ ID NOs. 606, 607, 608, and / or 609 (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0390] In some embodiments, the anti-IGSF8 antibody has VHs comprising one, two, three, or all of VH FR1, VH FR2, VH FR3, and / or VH FR4, each containing the amino acid sequence of SEQ ID NOs. 606, 607, 608, and / or 609, or an amino acid sequence substantially identical to SEQ ID NOs. 606, 607, 608, and / or 610 (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0391] In some embodiments, the anti-IGSF8 antibody has VHs comprising one, two, three, or all of VH FR1, VH FR2, VH FR3, and / or VH FR4, each containing the amino acid sequence of SEQ ID NOs. 647, 649, 651, and / or 610, or an amino acid sequence substantially identical to SEQ ID NOs. 647, 649, 651, and / or 610 (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0392] In some embodiments, the anti-IGSF8 antibody has VHs comprising one, two, three, or all of VH FR1, VH FR2, VH FR3, and / or VH FR4, each containing the amino acid sequence of SEQ ID NOs. 648, 649, 651, and / or 610, or an amino acid sequence substantially identical to SEQ ID NOs. 648, 649, 651, and / or 610 (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0393] In some embodiments, the anti-IGSF8 antibody has VHs comprising one, two, three, or all of VH FR1, VH FR2, VH FR3, and / or VH FR4, each containing the amino acid sequence of SEQ ID NOs. 648, 650, 651, and / or 610, or an amino acid sequence substantially identical to SEQ ID NOs. 648, 650, 651, and / or 610 (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0394] In some embodiments, the anti-IGSF8 antibody or its antigen-binding fragment has a light chain variable region (VL) containing one, two, three, or all (i.e., four) VL FR1, VL FR2, VL FR3, and / or VL FR4 amino acid sequences that are substantially identical (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity) to the corresponding light chain framework region of any one of the antibodies listed in Table D or G, or to the corresponding VL FR amino acid sequence of any one of the antibodies listed in Table D or G.

[0395] In some embodiments, the anti-IGSF8 antibody contains VL FR1 of an amino acid sequence substantially identical to SEQ ID NOs. 632, 633, 656, or 657 (for example, having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0396] In some embodiments, the anti-IGSF8 antibody contains a VL FR2 amino acid sequence that is substantially identical to SEQ ID NOs. 634, 635, 636, 637, 658, or 659 (for example, having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0397] In some embodiments, the anti-IGSF8 antibody contains a VL FR3 amino acid sequence that is substantially identical to (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity) of SEQ ID NOs. 638, 639, 640, 660, 661, 662, or 663.

[0398] In some embodiments, the anti-IGSF8 antibody contains a VL FR4 amino acid sequence that is substantially identical to SEQ ID NOs. 641, 642, 664, or 665 (for example, having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0399] In some embodiments, the anti-IGSF8 antibody has VLs containing VL FR1, VL FR2, VL FR3 and / or VL FR4, each containing the amino acid sequences of SEQ ID NOs. 632, 634, 638 and / or 641, or VLs containing one, two, three, or all of the amino acid sequences that are substantially identical to SEQ ID NOs. 632, 634, 638 and / or 641 (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0400] In some embodiments, the anti-IGSF8 antibody has VLs containing one, two, three, or all of VL FR1, VL FR2, VL FR3, and / or VL FR4, each containing the amino acid sequence of SEQ ID NOs. 633, 635, 639, and / or 642, or an amino acid sequence substantially identical to SEQ ID NOs. 633, 635, 639, and / or 642 (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0401] In some embodiments, the anti-IGSF8 antibody has VLs containing one, two, three, or all of VL FR1, VL FR2, VL FR3, and / or VL FR4, each containing the amino acid sequence of SEQ ID NOs. 632, 635, 639, and / or 64247, or an amino acid sequence substantially identical to SEQ ID NOs. 632, 635, 639, and / or 642 (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0402] In some embodiments, the anti-IGSF8 antibody has VLs containing one, two, three, or all of VL FR1, VL FR2, VL FR3, and / or VL FR4, each containing the amino acid sequence of SEQ ID NOs. 632, 636, 639, and / or 642, or an amino acid sequence substantially identical to SEQ ID NOs. 632, 636, 639, and / or 642 (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0403] In some embodiments, the anti-IGSF8 antibody has VLs containing one, two, three, or all of VL FR1, VL FR2, VL FR3, and / or VL FR4, each containing the amino acid sequence of SEQ ID NOs. 632, 637, 640, and / or 642, or an amino acid sequence substantially identical to SEQ ID NOs. 632, 637, 639, and / or 642 (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0404] In some embodiments, the anti-IGSF8 antibody has VLs containing one, two, three, or all of VL FR1, VL FR2, VL FR3, and / or VL FR4, each containing the amino acid sequence of SEQ ID NOs. 656, 658, 660, and / or 664, or an amino acid sequence substantially identical to SEQ ID NOs. 656, 658, 660, and / or 664 (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0405] In some embodiments, the anti-IGSF8 antibody has VLs containing one, two, three, or all of VL FR1, VL FR2, VL FR3, and / or VL FR4, each containing the amino acid sequence of SEQ ID NOs. 657, 659, 661, and / or 665, or an amino acid sequence substantially identical to SEQ ID NOs. 657, 659, 661, and / or 665 (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0406] In some embodiments, the anti-IGSF8 antibody has VLs containing one, two, three, or all of VL FR1, VL FR2, VL FR3, and / or VL FR4, each containing the amino acid sequence of SEQ ID NOs. 657, 659, 662, and / or 665, or an amino acid sequence substantially identical to SEQ ID NOs. 657, 659, 662, and / or 665 (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0407] In some embodiments, the anti-IGSF8 antibody has VLs containing one, two, three, or all of VL FR1, VL FR2, VL FR3, and / or VL FR4, each containing the amino acid sequence of SEQ ID NOs. 657, 659, 663, and / or 665, or an amino acid sequence substantially identical to SEQ ID NOs. 657, 659, 663, and / or 665 (e.g., having at least about 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 99% sequence identity).

[0408] In some embodiments, the monoclonal antibody or its antigen-binding fragment is a human-mouse chimeric antibody, a humanized antibody, a CDR-grafted antibody, or a resurfaced antibody.

[0409] In some embodiments, the antigen-binding fragment is Fab, Fab', F(ab')2, F d , single-chain Fv or scFv, disulfide-linked F v These include V-NAR domain, IgNar, intrabody, IgGΔCH2, minibody, F(ab')3, tetrabody, triabody, diabody, single-domain antibody, DVD-Ig, Fcab, mAb2, (scFv)2, or scFv-FC.

[0410] In some embodiments, the monoclonal antibody or its antigen-binding fragment has a K content of about 25 nM, 20 nM, 15 nM, 10 nM, 5 nM, 2 nM, or less than 1 nM. d It then binds with IGSF8.

[0411] In some embodiments, the antibody binds to IGSF8 from multiple species. For example, in some embodiments, the antibody binds to human IGSF8 and also to IGSF8 from at least one non-human mammal selected from mouse, rat, dog, guinea pig, and cynomolgus monkey.

[0412] In some embodiments, multiselective antibodies are provided. In some embodiments, bispecific antibodies are provided. Non-limiting exemplary bispecific antibodies include antibodies comprising a first arm comprising a heavy / light chain combination that binds to a first antigen and a second arm comprising a heavy / light chain combination that binds to a second antigen. Further non-limiting exemplary polyspecific antibodies are bivariable domain antibodies. In some embodiments, a bispecific antibody comprises a first arm that inhibits the binding of IGSF8 and a second arm that stimulates T cells by binding to, for example, CD3.

[0413] Another aspect of the present invention provides a monoclonal antibody or antigen-binding fragment thereof that competes with the monoclonal antibody or antigen-binding fragment thereof of the present invention described above.

[0414] In certain embodiments, the antibody or its antigen-binding site / fragment preferably has a K content of 5 nM or less, 2 nM or less, or 1 nM or less. D It then specifically binds to the D1 ECD (or Ig-V set domain) of IGSF8.

[0415] In certain embodiments, the antibody or its antigen-binding site / fragment inhibits the binding of IGSF8 to KIR3DL1 / 2.

[0416] In certain embodiments, the antibody or its antigen-binding site / fragment inhibits the binding of IGSF8 to the D2 domain of KIR3DL1 / 2, to epitopes including, for example, S165, I171, and / or M186 of KIR3DL1 / 2.

[0417] Another aspect of the present invention provides a monoclonal antibody or its antigen-binding site / fragment that specifically binds to the D1 ECD (or Ig-V set domain) of IGSF8 and inhibits binding to KIR3DL1 / 2, for example, to the D2 domain of KIR3DL1 / 2 (e.g., epitopes including S165, I171, and / or M186 of KIR3DL1 / 2).

[0418] In some embodiments, the monoclonal antibody or its antigen-binding site / fragment has a K content of 5 nM or less, 2 nM or less, or 1 nM or less. D It has.

[0419] In related embodiments, the present invention also provides polynucleotides encoding the monoclonal antibodies of the present invention, their heavy or light chains, or their antigen-binding sites / fragments. See separate sections below.

[0420] In a related embodiment, the present invention also provides polynucleotides that hybridize with the polynucleotide of the present invention or its complements under stringent conditions.

[0421] In related embodiments, the present invention also provides vectors comprising the polynucleotides of the present invention. See the following separate section.

[0422] In related embodiments, the present invention also provides host cells containing the polynucleotides of the present invention or vectors of the present invention for expressing an encoded monoclonal antibody, its heavy or light chain, or its antigen-binding site / fragment. See separate sections below.

[0423] In a related embodiment, the present invention also provides a method for producing a monoclonal antibody, its heavy or light chain, or its antigen-binding site / fragment, comprising: (i) culturing a host cell of the present invention capable of expressing the monoclonal antibody, its heavy or light chain, or its antigen-binding site / fragment under conditions suitable for expressing the monoclonal antibody, its heavy or light chain, or its antigen-binding site / fragment; and (ii) recovering / isolating / purifying the expressed monoclonal antibody, its heavy or light chain, or its antigen-binding site / fragment.

[0424] In a related embodiment, the present invention also provides a device or kit comprising at least one antibody, monoclonal antibody, its heavy or light chain, or its antigen-binding site / fragment, which optionally comprises a label for detecting at least one of the antibody, monoclonal antibody, its heavy or light chain, or its antigen-binding site / fragment, or a complex comprising at least one of the antibody, monoclonal antibody, its heavy or light chain, or its antigen-binding site / fragment.

[0425] Anti-IGSF8 antibodies according to the disclosure of the present invention can be prepared using any of the antibody sequences shown herein (e.g., variable domain amino acid sequences, variable domain amino acid sequence pairs, CDR amino acid sequences, variable domain CDR amino acid sequence sets, variable domain CDR amino acid sequence set pairs, and / or framework region amino acid sequences), any of which can be prepared, for example, as monoclonal antibodies, multispecific antibodies, chimeric antibodies, antibody mimetics, scFvs, or antibody fragments.

[0426] KIR3DL1 / 2 antibody One aspect of the present invention provides a monoclonal antibody specific to KIR3DL1 / 2. In certain embodiments, the monoclonal antibody is specific to the extracellular domain (ECD) of KIR3DL1 / 2. In certain embodiments, the monoclonal antibody is specific to the second Ig-like extracellular domain (D2 domain) of KIR3DL1 / 2 that is involved in IGSF8 binding. In some embodiments, an antibody that blocks binding to IGSF8 is provided. In certain embodiments, an anti-KIR3DL1 / 2 monoclonal antibody inhibits the binding of IGSF8 to KIR3DL2 and / or KIR3DL1, for example, inhibiting the binding of IGSF8 to residues S165, I171, and / or M186 of KIR3DL1 / 2.

[0427] In certain embodiments, the monoclonal antibody is specific to human KIR3DL1 / 2. In some embodiments, the anti-KIR3DL1 / 2 antibody inhibits signaling mediated by IGSF8 via KIR3DL1 / 2. In certain embodiments, the monoclonal antibody competes with any one of the anti-KIR3DL1 / 2 antibodies for binding to IGSF8.

[0428] In certain embodiments, the anti-KIR3DL1 / 2 antibody is a human-mouse chimeric antibody, a humanized antibody, a human antibody, a CDR graft antibody, or a resurfaced antibody.

[0429] In a particular embodiment, the antigen-binding fragment is Fab, Fab', F(ab')2, F d , single-chain Fv or scFv, disulfide-linked F v These include V-NAR domain, IgNar, intrabody, IgGΔCH2, minibody, F(ab')3, tetrabody, triabody, diabody, single-domain antibody, DVD-Ig, Fcab, mAb2, (scFv)2, or scFv-Fc.

[0430] In certain embodiments, the monoclonal antibody or its antigen-binding fragment has a K content of less than approximately 25 nM, less than 20 nM, less than 15 nM, less than 10 nM, less than 5 nM, less than 2 nM, or less than 1 nM. d It then binds with KIR3DL1 / 2.

[0431] Related embodiments provide a monoclonal antibody or antigen-binding fragment thereof that competes with the monoclonal antibody or antigen-binding fragment thereof of the present invention with respect to binding to KIR3DL1 / 2.

[0432] In certain embodiments, the antibody or its antigen-binding site / fragment comprises the second / intermediate / D2 ECD of KIR3DL1 / 2 and preferably a K content of 5 nM or less, 2 nM or less, or 1 nM or less. D It binds specifically to it.

[0433] In certain embodiments, the antibody or its antigen-binding site / fragment inhibits the binding of IGSF8 to KIR3DL1 / 2.

[0434] Another aspect of the present invention provides a monoclonal antibody or its antigen-binding site / fragment that specifically binds to the intermediate / D2 ECD of KIR3DL1 / 2 (for example, specifically binds to an epitope containing residues S165, I171, and / or M186), thereby inhibiting the binding of IGSF8 to KIR3DL1 / 2.

[0435] In certain embodiments, the monoclonal antibody or its antigen-binding site / fragment has a K content of 5 nM or less, 2 nM or less, or 1 nM or less. D It has.

[0436] 7. Humanized antibodies In some embodiments, the IGSF8 antibody is a humanized antibody. Humanized antibodies are useful as therapeutic molecules to reduce or eliminate human immune responses to non-human antibodies (e.g., human anti-mouse antibody (HAMA) responses) that can occur in response to antibody therapeutics and reduce the effectiveness of the therapeutic agent.

[0437] Antibodies can be humanized by standard methods. Non-limiting exemplary methods of humanization include, for example, the methods described in U.S. Patents 5,530,101; 5,585,089; 5,693,761; 5,693,762; 6,180,370; Jones et al., Nature 321:522-525 (1986); Riechmann et al., Nature 332:323-27 (1988); Verhoeyen et al., Science 239:1534-36 (1988); and U.S. Patent Publication No. 2009 / 0136500, all of which are incorporated by reference.

[0438] A humanized antibody is an antibody in which at least one amino acid in the framework region of a non-human variable region is substituted with an amino acid at the corresponding position in a human framework region. In some embodiments, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, at least nine, at least ten, at least 11, at least 12, at least 15, or at least 20 amino acids in the framework region of a non-human variable region are substituted with amino acids from one or more corresponding positions in one or more human framework regions.

[0439] In some embodiments, some of the corresponding human amino acids used for substitution are derived from framework regions of different human immunoglobulin genes. That is, in some such embodiments, one or more non-human amino acids may be substituted with corresponding amino acids derived from the human framework region of a first human antibody or encoded by the first human immunoglobulin gene, one or more non-human amino acids may be substituted with corresponding amino acids derived from the human framework region of a second human antibody or encoded by the second human immunoglobulin gene, and one or more non-human amino acids may be substituted with corresponding amino acids derived from the human framework region of a third human antibody or encoded by the third human immunoglobulin gene. Furthermore, in some embodiments, it is not necessary for all of the corresponding human amino acids used for substitution in a single framework region, e.g., FR2, to be derived from the same human framework. However, in some embodiments, all of the corresponding human amino acids used for substitution are derived from the same human antibody or encoded by the same human immunoglobulin gene.

[0440] In some embodiments, antibodies are humanized by replacing one or more entire framework regions with corresponding human framework regions. In some embodiments, human framework regions having the highest level of homology to the non-human framework region to be replaced are selected. In some embodiments, such humanized antibodies are CDR-grafted antibodies.

[0441] In some embodiments, following CDR grafting, one or more framework amino acids are reversed to their corresponding amino acids in the mouse framework region. Such “reverse mutations” are made in some embodiments to retain one or more mouse framework amino acids that are thought to contribute to the structure of one or more CDRs and / or may be involved in antigen contact and / or are thought to be involved in the overall structural integrity of the antibody. In some embodiments, mutations of 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1, or 0 are made in the framework region of the antibody after CDR grafting.

[0442] In some embodiments, the humanized antibody also includes a human heavy chain constant region and / or a human light chain constant region.

[0443] 8. Chimeric antibodies In some embodiments, the IGSF8 antibody is a chimeric antibody. In some embodiments, the IGSF8 antibody includes at least one non-human variable region and at least one human constant region. In some such embodiments, all variable regions of the IGSF8 antibody are non-human variable regions, and all constant regions of the IGSF8 antibody are human constant regions. In some embodiments, one or more variable regions of the chimeric antibody are mouse variable regions. The human constant region of the chimeric antibody does not need to be of the same isotype as the non-human constant region it substitutes for, if any. Chimeric antibodies are described, for example, in U.S. Patent No. 4,816,567; and Morrison et al., Proc. Natl. Acad. Sci. USA 81:6851~55 (1984).

[0444] 9. Human antibodies In some embodiments, the IGSF8 antibody is a human antibody. Human antibodies can be produced by any suitable method. Non-stationary exemplary methods include producing human antibodies in transgenic mice containing human immunoglobulin loci. For example, see Jakobovits et al., Proc.Natl.Acad.Sci.USA 90:2551~55(1993); Jakobovits et al., Nature 362:255~8(1993); onberg et al., Nature 368:856~9(1994); and U.S. Patents No. 5,545,807; No. 6,713,610; No. 6,673,986; No. 6,162,963; No. 5,545,807; No. 6,300,129; No. 6,255,458; No. 5,877,397; No. 5,874,299; and No. 5,545,806.

[0445] Non-limiting exemplary methods include the production of human antibodies using phage display libraries. See, for example, Hoogenboom et al., J.Mol.Biol.227:381~8(1992); Marks et al., J.Mol.Biol.222:581~97(1991); and PCT Publication, International Publication No. 99 / 10494.

[0446] Human antibody constant region In some embodiments, the humanized, chimeric, or human antibody described herein comprises one or more human constant regions. In some embodiments, the human heavy chain constant region is an isotype selected from IgA, IgG, and IgD. In some embodiments, the human light chain constant region is an isotype selected from K and λ. In some embodiments, the antibody described herein comprises a human IgG constant region, e.g., human IgG1, IgG2, IgG3, or IgG4. In some embodiments, the antibody or Fc fusion partner comprises, for example, a C237S mutation in the IgG1 constant region. In some embodiments, the antibody described herein comprises a human IgG2 heavy chain constant region. In some such embodiments, the IgG2 constant region comprises a P331S mutation, as described in U.S. Patent No. 6,900,292. In some embodiments, the antibody described herein comprises a human IgG4 heavy chain constant region. In some such embodiments, the antibody described herein comprises an S241P mutation in the human IgG4 constant region. See, for example, Angal et al., Mol.Immunol. 30(1):105-108 (1993). In some embodiments, the antibodies described herein include a human IgG4 constant region and a human κ light chain.

[0447] The selection of the heavy chain constant region can determine whether an antibody possesses effector function in vivo. In some embodiments, such effector function includes antibody-dependent cell-mediated cytotoxicity (ADCC) and / or complement-dependent cytotoxicity (CDC) and / or antibody-dependent cytophagocytosis (ADCP), which can result in the killing of cells to which the antibody is bound. Typically, antibodies containing human IgG1 or IgG3 heavy chains possess effector function.

[0448] In some embodiments, effector function is undesirable. For example, in some embodiments, effector function may be undesirable in the treatment of inflammatory conditions and / or autoimmune diseases. In some such embodiments, a human IgG4 or IgG2 heavy chain constant region is selected or manipulated. In some embodiments, the IgG4 constant region contains the S241P mutation.

[0449] In some other embodiments, where the objective of the antibody is to block the interaction between the receptor and the ligand, effector function may be undesirable if depletion of target cells is undesirable. In some such embodiments, a heavy chain constant region having Fc lacking effector function is selected or manipulated. Non-limiting examples of Fc with reduced effector function and mutations conferring reduced effector function to Fc are described, for example, in Liu et al., Antibodies 9:64 (2020), the entire content of which is incorporated herein by reference.

[0450] In some embodiments, the mutation that confers reduced effector function is the L234A / L235A mutation at the C1q binding site. In some embodiments, the heavy chain constant region with reduced effector function is human IgG1 or IgG4 containing the L234A / L235A mutation, also known as IgG1-L234A / L235A (IgG1-LALA) or IgG4-L234A / L235A (IgG4-LALA), respectively.

[0451] In some embodiments, the mutation conferring reduced effector function is the P329G mutation, which can interfere with the interaction between human IgG and human FcγR. In some embodiments, the mutation conferring reduced effector function is L234A / L235A / P329G. In some embodiments, the heavy chain constant region with reduced effector function is human IgG1 containing the L234A / L235A / P329G mutation, also known as IgG1-L234A / L235A / P329G (IgG1-LALA-PG).

[0452] In some embodiments, the mutations that confer reduced effector function are N297A, N297Q, or N297G mutations, which remove the glycan that is central to the binding between human IgG and C1q and FcγR. In some embodiments, the heavy chain constant region with reduced effector function is human IgG1 containing the N297A, N297Q, or N297G mutation, also known as IgG1-N297A / Q / G (IgG1-NA).

[0453] In some embodiments, the mutation that confers reduced effector function is the L235A / G237A / E318A mutation. In some embodiments, the heavy chain constant region with reduced effector function is human IgG1 containing the L235A / G237A / E318A mutation, also known as IgG1-L235A / G237A / E318A (IgG1-AAA).

[0454] In some embodiments, the mutation conferring reduced effector function is G236R / L328R, which may result in a decrease or complete elimination of binding to multiple FcγRs. In some embodiments, the heavy chain constant region with reduced effector function is human IgG1 containing the G236R / L328R mutation, also known as IgG1-G236R / L328R (IgG1-RR).

[0455] In some embodiments, the mutation conferring reduced effector function is the S298G / T299A mutation, which can eliminate or significantly reduce binding to C1q and most FcγR. In some embodiments, the heavy chain constant region with reduced effector function is IgG1 containing the S298G / T299A mutation, also known as IgG1-S298G / T299A (IgG1-GA).

[0456] In some embodiments, the mutation that confers reduced effector function is the L234F / L235E / P331S mutation, which can result in reduced binding to low-affinity FcγR and undetectable binding to FcγRI. In some embodiments, the heavy chain constant region with reduced effector function is human IgG1 containing the L234F / L235E / P331S mutation, also known as IgG1-L234F / L235E / P331S (IgG1-FES).

[0457] In some embodiments, the mutation that confers reduced effector function is the L234F / L235E / D265A mutation, which can result in strong silencing of the Fc region. In some embodiments, the heavy chain constant region with reduced effector function is human IgG1 containing the L234F / L235E / D265A mutation, also known as IgG1-L234F / L235E / D265A (IgG1-FEA).

[0458] In some embodiments, the mutation that confers reduced effector function is the E233P / L234V / L235A / G236del / S267K mutation, which may result in the absence of binding to multiple FcγRs. In some embodiments, the heavy chain constant region with reduced effector function is human IgG1 containing the E233P / L234V / L235A / G236del / S267K mutation, also known as IgG1--E233P / L234V / L235A / G236del / S267K.

[0459] In some embodiments, the mutation that confers reduced effector function is the 228P / L235E mutation in human IgG4 that prevents F9ab) arm replacement. In some embodiments, the heavy chain constant region with reduced effector function is human IgG4 containing the 228P / L235E mutation, also known as IgG4-S228P / L235E (IgG4-PE).

[0460] In some embodiments, the mutation that confers reduced effector function is the H268Q / V309L / A30S / P331S mutation. In some embodiments, the heavy chain constant region with reduced effector function is human IgG2 containing the H268Q / V309L / A30S / P331S mutation, also known as IgG2-H268Q / V309L / A30S / P331S (IgG2m4).

[0461] In some embodiments, the mutation that confers reduced effector function is the V234A / G237A / P238S / H268A / V309L / A330S / P331S mutation. In some embodiments, the heavy chain constant region with reduced effector function is human IgG2 containing the V234A / G237A / P238S / H268A / V309L / A330S / P331S mutation, also known as IgG2-V234A / G237A / P238S / H268A / V309L / A330S / P331S (IgG2c4d).

[0462] Any antibody described herein can be purified by any suitable method, including, but not limited to, the use of affinity matrices or hydrophobic interaction chromatography. Suitable affinity ligands include the antigen and / or epitope to which the antibody binds, as well as ligands that bind to the constant region of the antibody. For example, the constant region can be conjugated using a protein A, protein G, protein A / G, or antibody affinity column, and the antibody can be purified.

[0463] In some embodiments, hydrophobic interaction chromatography (HIC), such as butyl or phenyl columns, has also been used to purify some polypeptides. Many methods for purifying polypeptides are known in the art.

[0464] Alternatively, in some embodiments, the antibodies described herein are produced in a cell-free system. Non-limiting exemplary cell-free systems are described, for example, in Sitaraman et al., Methods Mol. Biol. 498:229~44 (2009); Sprin, Trends Biotechnol. 22:538~45 (2004); and Endo et al., Biotechnol. Adv. 21:695~713 (2003).

[0465] 10. Characteristics of Antibodies In some embodiments, the target IGSF8 antibody binds to IGSF8 and inhibits IGSF8-mediated signaling, such as the upregulation or downregulation of downstream genes as shown in Figures 4 and 5A-5D. In some embodiments, the IGSF8 antibody has a binding affinity (K) of less than 50 nM, less than 20 nM, less than 10 nM, or less than 1 nM. D ) or binds to IGSF8 at an EC50 value. In some embodiments, the degree of binding of the IGSF8 antibody to non-IGSF8 proteins unrelated to the antibody is less than 10% of the binding of the antibody to IGSF8 as measured, for example, by radioimmunoassay (RIA). In some embodiments, the IGSF8 antibody binds to an epitope of IGSF8 that is conserved among IGSF8 from different species. In some embodiments, the IGSF8 antibody binds to the same epitope as a human or humanized IGSF8 antibody that binds to humIGSF8. In some embodiments, the IGSF8 antibody is conjugated with a label that facilitates the detection of the antibody and / or the molecule to which the antibody binds. Examples of non-limiting labels include, but are not limited to, radioisotopes, fluorescent groups, enzyme groups, chemiluminescent groups, biotin, epitope tags, and metal-binding tags. Those skilled in the art can select an appropriate label depending on the intended application.

[0466] In some embodiments, the label is conjugated to the antibody using a chemical method in vitro. Non-limiting exemplary chemical methods of conjugation are known in the Art and include, for example, commercially available services, methods, and / or reagents from Thermo Scientific Life Science Research Produces (formerly Pierce; Rockford, IL), Prozyme (Hayward, CA), SACRI Antibody Services (Calgary, Canada), AbD Serotec (Raleigh, NC), etc. In some embodiments, if the label is a polypeptide, the label can be expressed from the same expression vector as at least one antibody chain to produce a polypeptide containing the label fused to the antibody chain.

[0467] 11. IGSF8 ECD, fusion, and low peptide In some embodiments, the IGSF8 antagonist is an IGSF8 polypeptide such as full-length IGSF8 or a fragment thereof that inhibits the binding of IGSF8 to its ligand.

[0468] In some embodiments, the IGSF8 fragment is the IGSF8 extracellular domain (ECD). In some embodiments, the IGSF8 fragment is the full-length IGSF8 ECD. In certain embodiments, the ECD functions as an antagonist polypeptide that inhibits the function of IGSF8 receptors such as KIR3dL1 / 2 resulting from wild-type IGSF8 binding. However, in other embodiments, the ECD functions as an agonist polypeptide that functions similarly to wild-type full-length IGSF8 on its receptor, such as KIR3DL1 / 2.

[0469] In some embodiments, the present invention provides an IGSF8 ECD fragment comprising, for example, at least 80%, at least 85%, at least 90%, or at least 95% of the full-length IGSF8 ECD amino acid sequence from which it is derived. In some embodiments, the IGSF8 ECD fragment comprises, or is derived from, the D1 (or most N-terminal Ig-V set) domain of IGSF8.

[0470] In some embodiments, the present invention provides IGSF8 ECD variants that, for example, have at least 80%, at least 85%, at least 90%, at least 92%, at least 95%, at least 97%, at least 98%, or at least 99% sequence identity with the full-length IGSF8 ECD or fragment from which it is derived (e.g., the Ig-V set D1 domain). In some embodiments, the variants retain the ability to bind KIR3DL1 / 2.

[0471] In other embodiments, the IGSF8 ECD is derived from a non-human IGSF8 ECD and may be full-length, fragment (e.g., D1 or Ig-V set domain), or variant (e.g., having at least 80%, at least 85%, at least 90%, at least 92%, at least 95%, at least 97%, at least 98%, or at least 99% sequence identity and retaining the ability to bind KIR3DL1 / 2).

[0472] In related embodiments, the present invention provides an IGSF8 variant that lacks the D2-D4 Ig-like C2 domain of ECD but retains the D1 Ig-V set domain of ECD. Such variants can substantially maintain the functionality of wt IGSF8, such as KIR3DL1 / 2 binding ability.

[0473] In some embodiments, IGSF8 or an IGSF8 fragment or IGSF8 variant is combined with at least one fusion partner.

[0474] Therefore, in some such embodiments, the present invention provides a fusion of full-length IGSF8, such as a C-terminal fusion with an Ig Fc region. In one embodiment, the Ig Fc fusion is a human IgG1 Fc fusion.

[0475] The present invention further provides a full-length IGSF8 ECD and at least one fusion partner for forming an IGSF8 ECD fusion molecule. In some embodiments, the IGSF8 ECD portion of the fusion molecule comprises an IGSF8 ECD fragment containing, for example, at least 80%, at least 85%, at least 90%, or at least 95% of the full-length IGSF8 ECD amino acid sequence from which it originates (e.g., the D1 or Ig-V set domain). In some embodiments, the IGSF8 ECD portion of the fusion molecule is an IGSF8 ECD variant that maintains binding to KIR3DL1 / 2 and has at least 80%, at least 85%, at least 90%, at least 92%, at least 95%, at least 97%, at least 98%, or at least 99% sequence identity with, for example, the full-length IGSF8 ECD (or the D1 or Ig-V set domain) from which it originates.

[0476] In other embodiments, the IGSF8 components are derived from non-human IGSF8 and may be full-length, fragments (e.g., ECD), or variants.

[0477] In any of the above embodiments of the fusion molecule (e.g., human IgG1 Fc), the fusion partner may include an immunoglobulin Fc molecule, such as a human Fc molecule. In other embodiments, the fusion partner may be a different molecule, such as albumin or polyethylene glycol (PEG). In some embodiments, one or more fusion partners may be bound to IGSF8 or its ECD. In some embodiments, the fusion partner (or more partners) is bound to the C-terminus, but other bindings are also possible, such as on an amino acid side chain or at the N-terminus. The binding of the fusion partner to IGSF8 or a fragment (e.g., ECD) or variant may be direct (i.e., by covalent bonding) or indirect via a linker. The linker may include, for example, at least one intervening amino acid or other chemical moiety, which plays a role in linking the fusion partner to the ECD by either covalent or non-covalent bonding.

[0478] In any of the embodiments described above, the IGSF8 polypeptide may be either a signal sequence or a mature form, i.e., a form without a signal sequence. The signal sequence may be derived from the native IGSF8 molecule or from another protein, for example, selected to enhance the expression of the IGSF8 polypeptide in cell culture.

[0479] In some embodiments, the IGSF8 ECD may include the following sequence: [ka]

[0480] In any of the above cases, the IGSF8 ECD may be part of a fusion molecule in which the above amino acid sequences are bound to a fusion partner either directly or via a linker such as Fc, albumin, or PEG. For example, in some embodiments, the IGSF8 ECD fusion molecule may include one of the above sequences and an immunoglobulin Fc sequence, or Fc derived from human IgG1. The IGSF8 ECD Fc fusion molecule may be formed by the direct binding of the IGSF8 ECD amino acid sequence to the Fc amino acid sequence, or via a linker (either an intervening amino acid, an amino acid sequence, or another chemical moiety).

[0481] In a related embodiment, the present invention provides a method for downregulating the function, viability, and / or activation of NK and / or T cells, comprising the step of contacting NK and / or T cells with the IGSF8 polypeptide of the present invention or a fusion thereof.

[0482] In a related embodiment, the present invention provides a method for treating a disease or condition such as an autoimmune disease or an excessive inflammatory response mediated by the activation of NK cells and / or T cells (for example, as in chronic inflammatory diseases), comprising the step of contacting NK cells and / or T cells with the IGSF8 polypeptide of the present invention or a fusion thereof.

[0483] In certain embodiments, autoimmune diseases are associated with excessive NK cell and / or T cell function or activation. In certain embodiments, autoimmune diseases include rheumatoid arthritis (RA), diabetes mellitus such as type 1 diabetes, psoriasis, psoriatic arthritis, ankylosing spondylitis, systemic sclerosis, multiple sclerosis, SLE, Sjögren's disease, antiphospholipid syndrome, plaque spondyloarthritis, spondyloarthritis, ulcerative colitis, uveitis, or Crohn's disease.

[0484] In certain embodiments, chronic inflammatory diseases include cardiovascular, neurodegenerative, diabetes, metabolic syndrome, periodontitis, and atherosclerosis.

[0485] In certain embodiments, the IGSF8 polypeptide comprises the full-length, ECD, or soluble fragment of IGSF8, which inhibits the proliferation, viability, and / or function of NK and / or T cells. In some embodiments, the IGSF8 ECD comprises, or is derived from, an Fc fusion of the ECD, such as an Fc fusion of the D1 (or Ig-V set) domain of IGSF8 that binds to KIR3DL1 / 2. In some embodiments, the Fc is a human IgG1 Fc fusion, a human IgG2 Fc fusion, a human IgG3 Fc fusion, or a human IgG4 Fc fusion. In some embodiments, the Fc is a human IgG1 Fc fusion. The fusion may be located at the C-terminus of IGSF8 or its fragment.

[0486] In some embodiments, the IGSF8 antagonist may be a small molecule or peptide, e.g., a small molecule peptide. In some embodiments, the IGSF8 antagonist may be a small molecule peptide containing the amino acid sequence of the IGSF8 ECD fragment. In some embodiments, the IGSF8 antagonist may be a small peptide containing residues S165-M186 of KIR3DL1 / 2. In some embodiments, the IGSF8 antagonist may be a small peptide having, for example, 5-50, 3-20, e.g., 3-15 or 3-10 amino acids, and this peptide may be linear or cyclic, having a sequence containing the IGSF8 fragment, the IGSF8 ECD fragment, or a variant of the IGSF8 fragment or IGSF8 ECD fragment. Such variants of IGSF8 may have, for example, at least 95%, at least 97%, or at least 99% sequence identity with respect to the native fragment sequence from which it is derived. In certain embodiments, an IGSF8-derived antagonist (such as an IGSF8 ECD fragment or its derivative) retains its binding ability to KIR3DL1 / 2 without causing the inhibitory function of IGSF8 on KIR3DL1 / 2, allowing the antagonist to function as a dominant negative inhibitor of IGSF8-mediated KIR3DL1 / 2 function.

[0487] In certain embodiments, any polypeptide of the present invention, including an antibody and its antigen-binding fragment, the IGSF8 polypeptide and its ECD, may have heterologous signal peptides at the time of synthesis. For some secretory proteins to be expressed and secreted in large quantities, heterologous protein-derived signal peptides may be desirable. Using heterologous signal peptides can be advantageous in that the signal peptides are removed in the ER during the secretory process, so the resulting mature polypeptide remains unchanged. The addition of heterologous signal peptides may be required for the expression and secretion of some proteins.

[0488] Sequences of non-exclusive, exemplary signal peptides are listed, for example, in the online signal peptide database maintained by the Department of Biochemistry, National University of Singapore. See Choo et al., BMC Bioinformatics, 6:249 (2005); and PCT Publication, International Publication No. 2006 / 081430.

[0489] 12. KIR3DL1 / 2 ECD, fusion, and small peptide In some embodiments, the KIR3DL1 / 2 antagonist is a KIR3DL1 / 2 polypeptide, for example, a fragment of KIR3DL1 / 2, or a fragment of IGSF8 that inhibits the binding of KIR3DL1 / 2 to IGSF8 (e.g., inhibits the binding of KIR3DL1 / 2 to the D1 or Ig-V set domain of IGSF8).

[0490] In some embodiments, the KIR3DL1 / 2 fragment is the KIR3DL1 / 2 extracellular domain (ECD). In some embodiments, the present invention provides a KIR3DL1 / 2 fragment comprising, for example, at least 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, or at least 95% of the full-length KIR3DL1 / 2 ECD amino acid sequence from which it is derived. In some embodiments, the fragment comprises an intermediate (second, or D2) Ig-like domain of KIR3DL1 / 2 that binds to IGSF8.

[0491] In some embodiments, the KIR3DL1 / 2 fragment is a full-length KIR3DL1 / 2 ECD. In some embodiments, the KIR3DL1 / 2 fragment is a partial KIR3DL1 / 2 ECD containing an intermediate (second, or D2) Ig-like domain that binds to IGSF8. In some embodiments, the KIR3DL1 / 2 fragment is essentially derived from, or comprises, an intermediate (second, or D2) Ig-like domain of KIR3DL1 / 2 that binds to IGSF8. In some embodiments, the KIR3DL1 / 2 fragment is essentially composed of, or comprises, a polypeptide or epitope containing residues S165 and M186 of KIR3DL1 / 2 that binds to IGSF8 and inhibits IGSF8 binding to KIR3DL1 / 2. In some embodiments, the polypeptide or epitope comprises about 25 residues, 30 residues, 35 residues, 40 residues, 45 residues, or about 50 residues. In some embodiments, the polypeptide or epitope independently comprises about 1–20, about 2–15, about 3–10, about 5–8, about 2–7, or about 3–5 residues of KIR3DL1 / 2 immediately at the N-terminus of S165, immediately at the C-terminus of M186, or both immediately at the N-terminus of S165 and immediately at the C-terminus of M186.

[0492] In some embodiments, the present invention provides KIR3DL1 / 2 ECD variants that have at least 80%, at least 85%, at least 90%, at least 92%, at least 95%, at least 97%, at least 98%, or at least 99% sequence identity with, for example, the full-length IGSF8 ECD or a fragment derived therefrom (e.g., the Ig-V set D1 domain). In some embodiments, the variants retain their ability to bind to KIR3DL1 / 2.

[0493] In other embodiments, the KIR3DL1 / 2 ECD is derived from a non-human KIR3DL1 / 2 ECD and may be full-length, fragment (e.g., D2 or intermediate Ig-like domain), or variant (e.g., having at least 80%, at least 85%, at least 90%, at least 92%, at least 95%, at least 97%, at least 98%, or at least 99% sequence identity and retaining the ability to bind to IGSF8).

[0494] In related embodiments, the present invention provides KIR3DL1 / 2 variants that lack the first or D Ig-like C2 domain of the ECD of KIR3DL1 / 2 but retain the D2 Ig-like domain of the ECD. Such variants can substantially maintain the functions of wt KIR3DL1 / 2, such as its ability to bind to IGSF8.

[0495] In some embodiments, KIR3DL1 / 2 or a fragment or variant is combined with at least one fusion partner.

[0496] Therefore, in some such embodiments, the present invention provides a full-length KIR3DL1 / 2 fusion, such as an ECD C-terminal fusion with an Ig Fc region. In one embodiment, the Ig Fc fusion is a human IgG1 Fc fusion.

[0497] In any of the above embodiments of the fusion molecule, the fusion partner may include an immunoglobulin Fc molecule, such as a human Fc molecule (e.g., human IgG1 Fc). In other embodiments, the fusion partner may be a different molecule, such as albumin or polyethylene glycol (PEG). In some embodiments, one or more fusion partners may be bound to KIR3DL1 / 2 or its ECD (e.g., an ECD fragment containing a D2 domain that binds to IGSF8). In some embodiments, the fusion partner (or more partners) is bound to the C-terminus of the ECD, but other bindings are also possible, such as on an amino acid side chain or at the N-terminus. The binding of the fusion partner to KIR3DL1 / 2 or a fragment (e.g., the ECD or D2 of the ECD) or variant may be direct (i.e., by covalent bonding) or indirect via a linker. The linker may include, for example, at least one intervening amino acid or other chemical moiety, which plays a role in linking the fusion partner to the ECD by either covalent or non-covalent bonding.

[0498] In any of the embodiments described above, the KIR3DL1 / 2 polypeptide may be either a signal sequence or a mature form, i.e., a form without a signal sequence. The signal sequence may be derived from the native KIR3DL1 / 2 molecule or from another protein, for example, selected to enhance the expression and / or secretion of the KIR3DL1 / 2 polypeptide / fragment in cell culture. In some embodiments, a protein tag may be included to facilitate concentration or purification.

[0499] In any of the above cases, the KIR3DL1 / 2 ECD may be part of a fusion molecule in which the above amino acid sequence is bound to a fusion partner either directly or via a linker such as Fc, albumin, or PEG. For example, in some embodiments, the ECD fusion molecule may include one of the above sequences and an immunoglobulin Fc sequence, or Fc derived from human IgG1. The ECD-Fc fusion molecule may be formed by direct binding of the KIR3DL1 / 2 ECD amino acid sequence to the Fc amino acid sequence, or via a linker (either an intervening amino acid, an amino acid sequence, or another chemical moiety). In some embodiments, the KIR3DL1 / 2 antagonist may be a small molecule or peptide, such as a small peptide. In some embodiments, the KIR3DL1 / 2 antagonist may be a small peptide containing the amino acid sequence of an IGSF8 ECD fragment that binds to the D2 domain of KIR3DL1 / 2 and inhibits the IGSF8-KIR3DL1 / 2 interaction, but does not cause inhibitory function of KIR3DL1 / 2 on NK cells (which can be quantified by IFNγ secretion by NK cells).

[0500] In some embodiments, the KIR3DL1 / 2 antagonist is a small peptide having, for example, 5-50, 3-20, 3-15, or 3-10 amino acids, which may be linear or cyclic and have a sequence containing an IGSF8 fragment, an IGSF8 ECD fragment, or a variant of an IGSF8 fragment or IGSF8 ECD fragment that inhibits IGSF8-KIR3DL1 / 2 binding. Such a variant of IGSF8 may have, for example, at least 95%, at least 97%, or at least 99% sequence identity with respect to the native fragment sequence from which it is derived.

[0501] In certain embodiments, any polypeptide of the present invention, including an antibody, its antigen-binding fragment, the polypeptide, and its ECD, may have heterologous signal peptides at the time of synthesis. For some secretory proteins to be expressed and secreted in large quantities, heterologous protein-derived signal peptides may be desirable. Using heterologous signal peptides can be advantageous in that the signal peptides are removed in the ER during the secretory process, so the resulting mature polypeptide remains unchanged. The addition of heterologous signal peptides may be required for the expression and secretion of some proteins.

[0502] Sequences of non-exclusive, exemplary signal peptides are listed, for example, in the online signal peptide database maintained by the Department of Biochemistry, National University of Singapore. See Choo et al., BMC Bioinformatics, 6:249 (2005); and PCT Publication, International Publication No. 2006 / 081430.

[0503] 13. Cotranslational modification and post-translational modification In some embodiments, polypeptides such as IGSF8 and / or KIR3DL1 / 2 or its ECD are modified in different ways during or after translation, for example by glycosylation, sialylation, acetylation, phosphorylation, amidation, derivatization with known protecting / blocking groups, proteolytic cleavage, or binding to antibody molecules or other cellular ligands. Many of these chemical modifications may be carried out by known techniques, including, but are not limited to, specific chemical cleavage by cyanogen bromide, trypsin, chymotrypsin, papain, V8 protease, NABH4, acetylation, formylation, oxidation, reduction, and / or metabolic synthesis in the presence of tunicamycin.

[0504] Further post-translational modifications encompassed by the present invention include, for example, N-linked or O-linked glycans, N-terminal or C-terminal processing, attachment of chemical moieties to the amino acid backbone, chemical modification of N-linked or O-linked glycans, and addition or deletion of an N-terminal methionine residue as a result of prokaryotic host cell expression.

[0505] 14. Nucleic acid molecules encoding IGSF8 antagonists and / or KIR3DL1 / 2 antagonists The present invention also provides nucleic acid molecules comprising polynucleotides encoding one or more chains of antibodies described herein, such as IGSF8 antibody and / or KIR3DL1 / 2 antibody. In some embodiments, the nucleic acid molecule comprises a polynucleotide encoding either the heavy chain or the light chain of an antibody described herein. In some embodiments, the nucleic acid molecule comprises both a polynucleotide encoding the heavy chain and a polynucleotide encoding the light chain of an antibody described herein. In some embodiments, the first nucleic acid molecule comprises a first polynucleotide encoding the heavy chain, and the second nucleic acid molecule comprises a second polynucleotide encoding the light chain.

[0506] In some such embodiments, the heavy and light chains are expressed as two separate polypeptides from one nucleic acid molecule or two separate nucleic acid molecules. In some embodiments, for example, if the antibody is scFv, a single polynucleotide encodes a single polypeptide containing both a heavy and light chain linked together.

[0507] In some embodiments, the polynucleotide encoding the heavy or light chain of the antibody described herein includes a nucleotide sequence encoding a leader sequence located at the N-terminus of the heavy or light chain during translation. As described above, the leader sequence may be a native heavy or light chain leader sequence, or it may be another heterogeneous leader sequence.

[0508] Nucleic acids encoding other IGSF8 antagonists and / or KIR3DL1 / 2 antagonists are also provided, including, for example, fragments or variants of IGSF8 containing an IGSF8 ECD molecule (e.g., a KIR3DL1 / 2-bound D1 Ig-V set domain) or an IGSF8 ECD fusion molecule, as well as fragments or variants of KIR3DL1 / 2 containing a KIR3DL1 / 2 ECD molecule (e.g., an intermediate or D2 IGSF8-bound Ig-like domain of KIR3DL1 / 2), or KIR3DL1 / 2 ECD fusion molecules and fragments or variants thereof. Nucleic acid molecules can be constructed using recombinant DNA techniques conventional in the art. In some embodiments, the nucleic acid molecule is an expression vector suitable for expression in selected host cells.

[0509] 15. Vector This specification provides vectors comprising polynucleotides encoding the heavy and / or light chains of antibodies described herein. Such vectors include, but are not limited to, DNA vectors, phage vectors, viral vectors, retroviral vectors, and the like. In some embodiments, the vector comprises a first polynucleotide sequence encoding the heavy chain and a second polynucleotide sequence encoding the light chain. In some embodiments, the heavy and light chains are expressed from the vector as two separate polypeptides. In some embodiments, the heavy and light chains are expressed as part of a single polypeptide, for example, when the antibody is an scFv.

[0510] In some embodiments, the first vector contains a polynucleotide encoding a heavy chain, and the second vector contains a polynucleotide encoding a light chain. In some embodiments, the first and second vectors are transfected into host cells in equal amounts (e.g., equal molar amounts or equal mass). In some embodiments, the first and second vectors are introduced into host cells in a molar or mass ratio of 5:1 to 1:5. In some embodiments, a mass ratio of 1:1 to 1:5 is used for the heavy chain-coding vector and the light chain-coding vector. In some embodiments, a mass ratio of 1:2 is used for the heavy chain-coding vector and the light chain-coding vector.

[0511] In some embodiments, a vector optimized for polypeptide expression in CHO cells or CHO-derived cells, or in NSO cells, is selected. Exemplary such vectors are described, for example, in Running Deer et al., Biotechnol. Prog. 20:880-889 (2004). In some embodiments, the vector is selected for in vivo expression of an IGSF8 antagonist in animals, including humans. In some such embodiments, polypeptide or polypeptide expression is under the control of a tissue-specific promoter or a group of promoters. For example, a liver-specific promoter is described, for example, in PCT Publication, International Publication No. 2006 / 076288.

[0512] 16.Host cells In various embodiments, the heavy and / or light chains of the antibodies described herein can be expressed in prokaryotic cells such as bacterial cells, or in eukaryotic cells such as fungal cells (e.g., yeast), plant cells, insect cells, and mammalian cells. Such expression can be carried out, for example, by procedures known in the Art. Exemplary eukaryotic cells that can be used to express polypeptides include, but are not limited to, COS cells, including COS7 cells; 293 cells, including 293-6E cells; CHO cells, including CHO-S and DG44 cells; PER.C6® cells (Crucell); and NSO cells. In some embodiments, the heavy and / or light chains of the antibodies described herein may be expressed in yeast. See, for example, U.S. Patent Application Publication No. 2006 / 0270045. In some embodiments, specific eukaryotic host cells are selected based on their ability to perform desired post-translational modifications on the heavy and / or light chains of the IGSF8 antibody. For example, in some embodiments, CHO cells produce polypeptides with a higher degree of sialylation than the same polypeptides produced by 293 cells.

[0513] The introduction of one or more nucleic acids into desired host cells can be achieved by any method, including but not limited to calcium phosphate transfection, DEAE-dextran-mediated transfection, cationic lipid-mediated transfection, electroporation, transduction, infection, and the like. Non-limiting exemplary methods are described, for example, in Sambrook et al., Molecular Cloning, A Laboratory Manual, 3rd edition, Cold Spring Harbor Laboratory Press (2001). Nucleic acids can be transiently or stably transfected in desired host cells according to any suitable method.

[0514] In some embodiments, one or more polypeptides may be produced in vivo in an animal manipulated or transfected with one or more nucleic acid molecules encoding the polypeptide, according to any suitable method.

[0515] 17. Methods for assay, diagnosis, and prognosis In a related embodiment, the present invention also provides an in vitro assay method for determining the ability of an anti-IGSF8 antagonist or anti-KIR3DL1 / 2 antagonist to inhibit IGSF8-KIR3DL1 / 2 binding, or a screening method for identifying an anti-IGSF8 antagonist or anti-KIR3DL1 / 2 antagonist (such as a small molecule or peptide antagonist) that inhibits IGSF8-KIR3DL1 / 2 binding, comprising the step of contacting a candidate anti-IGSF8 antagonist or candidate anti-KIR3DL1 / 2 antagonist (e.g., an antibody, a peptide fragment, or a small molecule) with an IGSF8 polypeptide and a KIR3DL1 / 2 polypeptide, wherein the IGSF8 polypeptide and / or KIR3DL1 / 2 polypeptide are labeled with a detectable signal, and inhibition of IGSF8-KIR3DL1 / 2 binding by the candidate anti-IGSF8 antagonist or anti-KIR3DL1 / 2 antagonist results in a detectable or measurable change of the detectable signal.

[0516] In a related embodiment, the present invention also provides an in vitro assay method for determining the ability of an anti-IGSF8 antagonist or anti-KLRC1 / D1 antagonist to inhibit IGSF8-KLRC1 / D1 binding, or a screening method for identifying an anti-IGSF8 antagonist or anti-KLRC1 / D1 antagonist (such as a small molecule or peptide antagonist) to inhibit IGSF8-KLRC1 / D1 binding, comprising the step of contacting a candidate anti-IGSF8 antagonist or candidate anti-KLRC1 / D1 antagonist (e.g., an antibody, a peptide fragment, or a small molecule) with an IGSF8 polypeptide and a KLRC1 / D1 polypeptide, wherein the IGSF8 polypeptide and / or KLRC1 / D1 polypeptide are labeled with a detectable signal, and inhibition of IGSF8-KLRC1 / D1 binding by the candidate anti-IGSF8 antagonist or anti-KLRC1 / D1 antagonist results in a detectable or measurable change of the detectable signal.

[0517] In one embodiment, the IGSF8 polypeptide comprises the D1 or Ig-V set domain of IGSF8 responsible for KIR3DL1 / 2 binding, and the KIR3DL1 / 2 polypeptide comprises the D2 (or intermediate) Ig-like domain of KIR3DL1 / 2.

[0518] In one embodiment, the IGSF8 polypeptide is immobilized on a solid support or expressed on cells such as cells that do not express MHC class I (HLA) receptors. An exemplary cell is K562, which stably or inductively expresses exogenous IGSF8, and can be introduced into K562 cells by a vector such as a lentiviral vector encoding the IGSF8 polypeptide. In another embodiment, the cell is CT26 cells (ATCC CRL-2638™ mouse colon cancer species) expressing exogenous IGSF8.

[0519] In one embodiment, the KIR3DL1 / 2 polypeptide is labeled with a detectable signal such as biotin. The biotin label can be detected by a streptavidin-linked signal such as PE-streptavidin.

[0520] In an alternative embodiment, the IGSF8 polypeptide and the KIR3DL1 / 2 polypeptide can be labeled with molecules that suppress fluorescence emission when the fluorescent molecule and inhibitor are in close proximity to each other, but generate a fluorescent signal when the antagonist inhibits IGSF8-KIR3DL1 / 2 binding.

[0521] In a related embodiment, the present invention provides a method for detecting the presence or level of IGSF8 polypeptide in a sample, comprising the step of contacting the IGSF8 polypeptide in the sample with an antibody, monoclonal antibody, or antigen-binding moiety / fragment thereof of the present invention, wherein the antibody, monoclonal antibody, or antigen-binding moiety / fragment thereof is labeled with a detectable label or can be attached to a detectable label.

[0522] In certain embodiments, the antibody,...

Claims

1. An isolated or recombinant monoclonal antibody or its antigen-binding fragment specific to IGSF8, wherein the monoclonal antibody or its antigen-binding fragment comprises a heavy chain variable region (VH) including VH CDR1, VH CDR2, and VH CDR3 of the antibody in Table D, and a light chain variable region (VL) including VL CDR1, VL CDR2, and VL CDR3. (i) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 614, 625, and 631, respectively; (ii) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 611, 623, and 631, respectively; (iii) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 612, 623, and 631, respectively; (iv) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 611, 624, and 631, respectively; (v) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 611, 625, and 631, respectively; (vi) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 613, 623, and 631, respectively; (vii) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 614, 623, and 631, respectively; (viiii) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 615, 623, and 631, respectively; (ix) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 616, 623, and 631, respectively; (x) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 611, 626, and 631, respectively; (xi) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 611, 627, and 631, respectively; (xi) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 617, 623, and 631, respectively; (xiiii) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 611, 628, and 631, respectively; (xiv)VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 611, 629, and 631, respectively; (xv)VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 611, 630, and 631, respectively; (xvi) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 618, 623, and 631, respectively; (xvii) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 614, 625, and 631, respectively; (xviiii) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 614, 629, and 631, respectively; (xix)VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 614, 625, and 631, respectively; (xx)VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 619, 629, and 631, respectively; (xxi) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 615, 625, and 631, respectively; (xxii) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 614, 625, and 631, respectively; (xxiii)VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 620, 625, and 631, respectively; (xxiv) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 621, 625, and 631, respectively; (xxv)VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 620, 625, and 631, respectively; (xxvi) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 619, 625, and 631, respectively; (xxvii) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 622, 625, and 631, respectively; (xxviiii)VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 615, 625, and 631, respectively; (xxix)VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 614, 629, and 631, respectively; (xxx)VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 602, 605, 614, 628, and 631, respectively; (xxxi)VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 603, 605, 614, 624, and 631, respectively; (xxxii) VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 604, 605, 614, 625, and 631, respectively; or, (xxxiii)VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain the amino acid sequences of SEQ ID NOs. 601, 603, 605, 614, 625, and 631, respectively; The monoclonal antibody or its antigen-binding fragment.

2. The monoclonal antibody or antigen-binding fragment according to claim 1, wherein VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 each contain or consist of the amino acid sequences of SEQ ID NOs. 601, 602, 605, 614, 625, and 631, respectively.

3. (a) VH includes VH FR1, VH FR2, VH FR3, and / or VH FR4, which include (i) the amino acid sequence of the VH FR sequence of any one or more antibodies in Table D, (ii) an amino acid sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% sequence identity with the VH FR sequence of any one or more antibodies in Table D; or (iii) an amino acid sequence having up to 1, 2, 3, 4, or 5 substitutions, deletions, and / or additions compared to the VH FR sequence of any one or more antibodies in Table D; and / or (b) A monoclonal antibody or antigen-binding fragment thereof according to claim 1 or 2, wherein the VL comprises (i) an amino acid sequence of the VL FR sequence of any one or more antibodies in Table D; (ii) an amino acid sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% sequence identity with the VL FR sequence of any one or more antibodies in Table D; or (iii) VL FR1, VL FR2, VL FR3, and / or VL FR4 having up to 1, 2, 3, 4, or 5 substitutions, deletions, and / or additions compared to the VL FR sequence of any one or more antibodies in Table D.

4. The VH and VL sequences each contain the amino acid sequences of the VH and VL sequences of any one antibody in Table D, or The VH and VL sequences contain the amino acid sequences of SEQ ID NOs. 670 and 694, respectively. A monoclonal antibody or its antigen-binding fragment according to any one of claims 1 to 3.

5. (i) Whether the monoclonal antibody is a human antibody, (ii) Antigen-binding fragments are Fab, Fab', F(ab') ２ F ｄ , single-chain Fv or scFv, disulfide-linked F ｖ Intrabody, IgGΔCH ２ Mini body, F (ab') ３ Tetrabody, Triabody, Diabody, DVD-Ig, Fcab, mAb ２ (scFv) ２ , or scFv-Fc, A monoclonal antibody or its antigen-binding fragment according to any one of claims 1 to 4.

6. Includes a heavy chain constant region, (a) The heavy chain constant region is wild-type human IgG1, human IgG2, human IgG3, or human IgG4; or (b) A monoclonal antibody or antigen-binding fragment thereof according to any one of claims 1 to 5, wherein the heavy chain constant region has an Fc domain that is deficient in antibody-dependent cell-mediated cytotoxicity (ADCC), complement-dependent cell-mediated cytotoxicity (CDC), and / or antibody-dependent cell-mediated phagocytosis (ADCP).

7. The heavy chain constant region having a missing Fc domain is as follows: IgG1-N297A / Q / G (IgG1-NA), IgG1-L235A / G237A / E318A (IgG1-AAA), IgG1-G236R / L328R (IgG1-RR), IgG1-S298G / T299A (IgG1-GA), IgG1-L234F / L235E / P331S (IgG1-FES), IgG1-L234F / L235E / D265A (IgG1-FEA), Ig A monoclonal antibody or its antigen-binding fragment according to claim 6, selected from the group consisting of G4-S228P / L235E (IgG4-PE), IgG1-E233P / L234V / L235A / G236del / S267K, IgG2-H268Q / V309L / A30S / P331S (IgG2m4), and IgG2-V234A / G237A / P238S / H268A / V309L / A330S / P331S (IgG2c4d).

8. The monoclonal antibody or its antigen-binding fragment has a K content of less than approximately 25 nM, less than 20 nM, less than 15 nM, less than 10 nM, less than 5 nM, less than 2 nM, or less than 1 nM. ｄ A monoclonal antibody or its antigen-binding fragment according to any one of claims 1 to 7, which binds to IGSF8.

9. A monoclonal antibody according to any one of claims 1 to 8, its heavy chain or light chain, or a polynucleotide encoding an antigen-binding site / fragment thereof.

10. A vector comprising the polynucleotide described in claim 9.

11. A host cell comprising a polynucleotide according to claim 9, or a vector according to claim 10, for expressing an encoded monoclonal antibody, its heavy chain or light chain, or its antigen-binding site / fragment.

12. A method for producing a monoclonal antibody according to any one of claims 1 to 8, its heavy chain or light chain, or its antigen-binding site / fragment, (i) A step of culturing a host cell according to claim 11, which is capable of expressing the monoclonal antibody, its heavy chain or light chain, or its antigen-binding site / fragment, under conditions suitable for expressing the monoclonal antibody, its heavy chain or light chain, or its antigen-binding site / fragment; and, if necessary, (ii) A process of recovering, isolating, and purifying the expressed monoclonal antibody, its heavy chain or light chain, or its antigen-binding site / fragment. The method, including the method described above.

13. An anti-IGSF8 monoclonal antibody or an antigen-binding fragment thereof, as described in any one of claims 1 to 8, for use in a method of modulating an immune response in a subject requiring such use, or in a method of treating cancer.

14. The anti-IGSF8 monoclonal antibody or its antigen-binding fragment according to claim 13, wherein the anti-IGSF8 monoclonal antibody or its antigen-binding fragment is conjugated to a cytotoxic substance.

15. The anti-IGSF8 monoclonal antibody or its antigen-binding fragment according to claim 14, wherein the cytotoxic substance is selected from the group consisting of chemotherapeutic agents, biological agents, toxins, and radioisotopes.

16. Cancers include melanoma (including cutaneous melanoma), cervical cancer, lung cancer (e.g., non-small cell lung cancer, lung adenocarcinoma, lung squamous cell carcinoma), colorectal cancer (including colon cancer), lymphoma (including B-cell lymphoma and diffuse large B-cell lymphoma (DLBCL)), leukemia (including chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML)), bladder cancer, breast cancer, head and neck cancer, head and neck squamous cell carcinoma, thyroid cancer, urothelial carcinoma, and uterine cancer (intrauterine cancer). An anti-IGSF8 monoclonal antibody or an antigen-binding fragment thereof according to any one of claims 13 to 15, wherein the cancer is a uterine cancer, including uterine cancer, endometrial cancer (UCEC), esophageal cancer, liver cancer, ganglion cancer, kidney cancer, pancreatic cancer, pancreatic ductal cancer, ovarian cancer, prostate cancer, gastric cancer, ovarian cancer, glioma, glioblastoma, neuroblastoma, thymoma, cholangiocarcinoma, soft tissue sarcoma, T-cell lymphoma, and cancer in which immune cells expressing the IGSF8 receptor have infiltrated.

17. An anti-IGSF8 monoclonal antibody or its antigen-binding fragment according to any one of claims 13 to 16, wherein cancer cells and / or tumor immune-infiltrating cells in the target express IGSF8.

18. The anti-IGSF8 monoclonal antibody or its antigen-binding fragment according to claim 17, further comprising the step of administering an effective amount of a second therapeutic agent, which includes an immunotherapy agent, an immune checkpoint inhibitor, a cancer vaccine, a chimeric antigen receptor, a chemotherapeutic agent, a radiotherapy agent, an anti-angiogenic agent, a growth inhibitor, an immuno-oncological agent, an antineoplastic composition, or a combination thereof, to a target.

19. An immune checkpoint inhibitor is an antibody or antigen-binding fragment thereof specific to PD-1, PD-L1, PD-L2, LAG3, TIGIT, TIM3, NKG2A, CD276, VTCN1, VISR, or HHLA2; or, The immune checkpoint inhibitor is an anti-PD-1 antibody, such as cemiprimab, nivolumab, or pembrolizumab; or, The immune checkpoint inhibitor is an anti-PD-L1 antibody, such as avelumab, durvalumab, atezolizumab, KN035, or CK-301; or, The immune checkpoint inhibitors are PD-1 / PD-L1 (non-antibody) peptide inhibitors, e.g., AUNP12; PD-L1 small molecule inhibitors, e.g., CA-170; or macrocyclic peptides, e.g., BMS-986189; or The second therapeutic agent is an antibody or its antigen-binding site / fragment effective in treating cancer, such as 3F8, 8H9, avagovomab, absiximab, abituzumab, abrazekimab, abrilumab, actokisumab, adalimumab, adecatumumab, aducanumab, afasebicumab, aferimomab, aracizumab pegol, alemtuzumab, alirocumab, artumomab penteate, amatsuximab, amivantamab, anatumomab mafenatox, anddecaliximab, anetumablubutansine, aniflorumab, anlukinzumab, apolizumab Apultumab ixadotin, alsitumomab, askrinbakumab, aselizumab, atezolizumab, atidolotoxumab, atinumab, atrolimumab, avelumab, adintuxizumab vedotin, bapineozumab, basiliximab, bavituximab, BCD-100, vectumomab, begeromab, verantamab mahodotin, belimumab, bemarituzumab, benralizumab, berlimatoxumab, bermekimab, bersanlimab, bertilimumab, besilezomab, bevacizumab, bezlotoxumab, bisilomab, bimagrumab, bimekizumab, birta Mimab, vibatuzumab, preserumab, blinatumomab, brontubetomab, brosozumab, vococizumab, brazicumab, brentuximab vedotin, briakinumab, brodalumab, brolucizumab, bronticutuzumab, brosumab, kabilizumab, camidanrumab tesirin, camrelizumab, canakinumab, cantuzumab meltansine, cantuzumab brabutansine, caplacizumab, capromab, carrumab, carotuximab, catumakisomab, cBR-doxorubicin immunoconjugate, sedelizumab, semiprimab, sergutuzumab Munaloykin, certolizumab pegol, cetrelimab, cetuximab, sibisatamab, silimutuzumab, sitatuzumab bogatox, ixutumumab, crazakizumab, clenoliximab, cribatuzumab tetraxetan, codlituzumab, cofetuzumab peridotin, coltuximab labutancin, conatumumab, concizumab, cosflobiximab, crenezumab, chryzanlizumab, clotedumab, CR6261, kusatuzumab, dasetuzumab, dacrizumab, darotuzumab, dapirolizumab pegol, daratumumab, dectrekumab, demcizumab,Denintuzumab mahodotin, denosumab, depatuxizumab mahodotin, delrotuximab biotin, detumomab, dezamizumab, dinutuximab, ziridabumab, domaglozumab, dorulimomab aritox, dostalurimab, dorodizumab, DS-8201, durigotuzumab, dupilumab, durvalumab, dusigituzumab, duvortuxizumab, eclomeximab, eculizumab, edovacomab, edrecolomab, efalizumab, efangumab, erderumab, erezanumab, elgemzumab, elotuzumab, erucilimomab, emactuzumab Mab, emapalmab, emibetuzumab, emicizumab, enapotamab vedotin, enabatuzumab, enfortumab vedotin, enrimomab pegol, enobrituzumab, enokizumab, enoticumab, encituximab, epitumomab citucetan, epratuzumab, eptinezumab, erenumab, erulizumab, erzmaxomab, etalacizumab, etigirimab, etorilizumab, evinacumab, evolocumab, exvivirumab, fanolesomab, falarimomab, falisimab, faretuzumab, facinumab, FBTA05, felbizumab, Fezakinumab, fibatuzumab, ficratuzumab, figtumumab, firivumab, framotumab, freticumab, flotetuzumab, fontrizumab, foralumab, folavirumab, fremanezumab, fresolimmab, flobocimab, flunebetomab, fluranumab, futuximab, galcanezumab, galiximab, gancotamab, ganitumab, gantenerumab, gatipotuzumab, gabirimomab, gezibumab, gemtuzumab ozogamicin, gebokizumab, zilbetomab, dimicirumab, dilentuximab, glenbatumumab vedotin, golim Mab, Gomiliximab, Goslanemab, Guselkumab, Ranalumab, Ibalizumab, IBI308, Ibritumomab tiuxetan, Icurcumab, Idarucizumab, Ifabotuzumab, Igobomab, Iradatuzumab vedotin, IMAB363, Imarumab, Imaprelimab, Imusilomab, Imugatuzumab, Incrakumab, Indatuximab tansine, Indusatuzumab vedotin, Innebilizumab, Infliximab, Intetumumab, Inorimomab, Inotuzumab ozogamicin, Ipilimumab, Iomab-B, Iratumumab, IsatuximabIscarimab, istilatumab, itorizumab, ixekizumab, keriximab, lavetuzumab, lacunotuzumab, radilatuzumab vedotin, lamparizumab, lanadelumab, landgrozumab, laprituximab emtansine, larcabiximab, lebrikizumab, remaresomab, lendarizumab, lembervimab, rendilumab, reldelimumab, leronlimab, resofabumab, letrizumab, lesatumumab, rivivirumab, rifastuzumab vedotin, rigerizumab, loncastuzumab tesirin, rosatuzumab vedotin, rilotomab Tetraxetan, lintuzumab, lirirumab, rodelcizumab, lokibetomab, rorbotuzumab meltansine, lucatumumab, rulizumab pegol, lumiliximab, lumuretuzumab, lupalzumab, lupalzumab amadotin, lutikizumab, mapatumumab, marjetuximab, malstacimab, masulimomab, mapurilimumab, matsuzumab, mepolizumab, metelimumab, milatuzumab, minretumomab, mirikizumab, milbetuximab sorabtansine, mitumomab, modotuximab, mogamulizumab, monalizumab, morolimumab, mosnetuzumab Motabizumab, Moxetumomab Pasdotox, Muromonab-CD3, Nacolomabutafenatox, Namilumab, Naptumomab Estafenatox, Naratuximab Emtansine, Narunatumab, Natalizumab, Navixixizumab, Navibumab, Naxitamab, Nevacumab, Necitumumab, Nemolizumab, NEOD001, Nerelimomab, Nesbacumab, Netakimab, Nimotuzumab, Nilsevimab, Nivolumab, Nofetumomab Merpentan, Oviltoxakimab, Obinutuzumab, Okalatuzumab, Oclelizumab, Odurimomab, Ofatum Olaratumab, Olekurmab, Orendalizumab, Orokizumab, Omalizumab, Ombrutamab, OMS721, Onartuzumab, Ontuxizumab, Onbachirimab, Opicinumab, Oportuzumab Monatox, Olegobomab, Orticumab, Oterixizumab, Ochirimab, Otreltuzumab, Oxerumab, Ozanezumab, Ozoralizumab, Padibaximab, Palivizumab, Pamrebrumab, Panitumumab, Pancomab, Panobacumab, Pulsatuzumab, Pasocolizumab, Pasotuxizumab, Pateclizumab, Patrizumab, PDR001,Pembrolizumab, pemtumomab, perakizumab, partzumab, paxerizumab, pidilizumab, pinatuzumab vedotin, pintumomab, prakmab, prezalumab, prozarizumab, pogalizumab, polatuzumab vedotin, ponezumab, polgabiximab, pracinezumab, prezarizumab, priliximab, pritoxaximab, pritumumab, PRO140, kirizumab, lakosumomab, radrezumab, rafibirumab, larpancizumab, ramucirumab, lanebetomab, ranibizumab, laxibakumab, labagalimab, ravulizumab, Fanezumab, regavirumab, REGN-EB, relatrimab, remtolumab, reslizumab, rilotumumab, linucumab, risankizumab, rituximab, ribabzumab pegol, lobatumumab, Rmab, lorezumab, romilukimab, romosozumab, lontalizumab, rosmantuzumab, lovalpituzumab tesirin, loberizumab, rozanolixizumab, luprizumab, SA237, sacituzumab govitecan, samarizumab, samlotamab vedotin, sarilumab, satralizumab, saturomab pendetide, secukinumab, sericrelumab, serivantuzumab , cetoxaximab, cetolumab, sevilumab, cibrotuzumab, SGN-CD19A, SHP647, cifarimumab, siltuximab, simtuzumab, ciprizumab, siltratuzumab vedotin, silutuzumab, sofituzumab vedotin, solanezumab, solitomab, sonepcizumab, sontuzumab, spartalizumab, stamlumab, thresomab, subutabumab, stimulimab, subizumab, sublatoxumab, tabarumab, takatuzumab tetraxetan, tadocizumab, talakotsuzumab, talizumab, taluketamab, tamtuvetomab, tanezumab Tapritumomab paptox, tarextumab, taborimab, tecristamab, tefibazumab, terimomab aritox, terisotuzumab, terisotuzumab vedotin, tenatumomab, teneriximab, teprizumab, tepozitamab, teprotumumab, tesidorumab, tetulomab, tezeperumab, TGN1412, tibrizumab, tildrakizumab, tigatuzumab, timigutuzumab, timorumab, tilagorumab, tilagotumab, tislerizumab, tisotuzumab vedotin, TNX-650, tocilizumab, tomzotuximab, tralizumab, tosatoxumab,Tositumomab, Tobetumab, Tralokinumab, Trastuzumab, Trastuzumab Duocalmazine, Trastuzumab Emtansine, TRBS07, Tregalizumab, Tremelimumab, Trevoglumab, Tucotsuzumab Cermoloukin, Tubilumab, Ublituximab, Urocpurumab, Urelumab, Urotoxazumab, Ustekinumab, Utomirumab, Vadastuzumab Butarilin, Banarimab, Bundutuzumab Vedotin, Vanuchikutuzumab, Vanucizumab, Vapariximab This includes valisakumab, valirulumab, baterizumab, vedolizumab, beltuzumab, bepalimomab, besenkumab, vizilizumab, bovalilizumab, borosiximab, bonrelorizumab, voplaterimab, borsetuzumab mahodotin, botumumab, bunakizumab, xentuzumab, XMAB-5574, zaltumumab, zanolimmumab, zatuximab, xenoctuzumab, diralimumab, zolbetuximab, zolimomab aritox, or combinations thereof; or, The second therapeutic agent comprises an antibody or its antigen-binding site / fragment that is effective in inducing ADCC, ADCP, and / or CDC. The anti-IGSF8 monoclonal antibody or its antigen-binding fragment according to claim 18.

20. A method for monitoring the progression of disorders associated with abnormal (e.g., higher than normal) IGSF8 expression in a subject, a) A step of detecting a first level of IGSF8 in a sample obtained from a subject at a first time point using an antibody, monoclonal antibody, or its antigen-binding site / fragment according to any one of claims 1 to 8; b) At a subsequent point in time, repeat step a) to obtain a second level of IGSF8; and c) A process to monitor the progression of the fault in the target by comparing the first and second levels of IGSF8 detected in steps a) and b). Includes, The method wherein a second level higher than the first level indicates that the disease has progressed.

21. A method for evaluating the effectiveness of therapy for disorders associated with abnormal (e.g., higher than normal) IGSF8 expression in a subject, a) Before providing at least a portion of the therapy to the subject, the step of determining the level of IGSF8 in a first sample obtained from the subject using the antibody, monoclonal antibody, or antigen-binding site / fragment thereof described in any one of claims 1 to 8, and b) A step in which step a) is repeated with a second sample obtained from the subject, following the provision of a portion of the therapy. Includes, Is a significantly lower level of IGSF8 in the second sample compared to the first sample (a decrease of >20%, >50%, or more) an indicator that the therapy is effective in inhibiting the impairment in the subject?; and / or, The method wherein substantially identical or higher levels of IGSF8 in the second sample compared to the first sample indicate that the therapy is ineffective in inhibiting the disorder in the subject.

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