BCMA-BINDING ANTIBODIES AND USES THEREOF

Abstract

The present invention relates to affinity enhanced antibodies that specifically bind to BCMA and antibodies comprising the P329G mutation, as well as complexes, fusions, bispecific antibodies or pharmaceutical compositions comprising said antibodies. The present invention also relates to nucleic acids encoding said antibodies and host cells comprising said nucleic acids, as well as methods for producing said antibodies. The present invention further relates to therapeutic and diagnostic uses of these antibodies that bind to BCMA.

Description

[Technical field]

[0001] The present invention relates to the field of antibody drugs. Specifically, the present invention relates to affinity-enhanced antibodies that specifically bind to B-cell maturation antigen (BCMA) and antibodies comprising the P329G mutation and compositions comprising said antibodies. The present invention also relates to nucleic acids encoding said antibodies and host cells comprising said nucleic acids, as well as methods for preparing said antibodies. The present invention further relates to therapeutic and diagnostic uses of these antibodies that bind to BCMA. [Background technology]

[0002] B-cell maturation antigen (BCMA, i.e. CD269, TNFRSF17) is a tumor necrosis factor receptor superfamily member (TNFRSF). BCMA is a type III transmembrane protein that has a characteristic cysteine-rich domain (CRD) of TNFR family members in its extracellular domain (ECD), which forms a ligand-binding motif. Ligands for BCMA include B-cell activating factor (BAFF) and B-cell proliferation-inducing ligand (APRIL), where APRIL binds to BCMA with higher affinity and promotes tumor cell proliferation.

[0003] BCMA is mainly expressed on the surface of mature B cells, i.e., plasma cells, but not on normal hematopoietic stem cells and non-blood derived tissues, and BCMA signaling is essential for long-acting bone marrow plasma cell survival, but not for the stability of whole B cells. Membrane surface BCMA can be cleaved and shed by γ-secretase, and the produced soluble BCMA (sBCMA) can reduce the signaling of membrane surface BCMA by blocking BAFF / APRIL ligand binding. It has been found in preclinical models and human tumors that BCMA is overexpressed in multiple myeloma (MM) cells, upregulates classical and non-classical NF-κB signals, promotes MM cell growth, survival, and adhesion, induces osteoclast activation, angiogenesis, metastasis, and immunosuppression, and BCMA expression has become an important marker for diagnosing MM. Furthermore, elevated levels of sBCMA in MM patient serum are positively proportional to the number of MM cells in the bone marrow, and changes in its concentration are closely related to MM prognosis and treatment response.

[0004] Multiple myeloma, also known as plasmacytoma or Köhler's disease, is an intractable malignant tumor of B cell lineage characterized by abnormal proliferation of plasma cells. Given the characteristic that BCMA is only expressed in plasma cells, but not in natural and memory B cells, BCMA has become a hot target for treating B cell malignancies, especially multiple myeloma. There is still a need in the art for new BCMA-specific binding molecules. The present invention meets this need by providing an antibody that binds to BCMA with high target specificity and high affinity, and in particular binds to BCMA expressed on the surface of tumor cells. Summary of the Invention

[0005] Through research, the present inventors have developed a set of novel anti-BCMA antibodies that bind to BCMA with high affinity. The antibodies or antigen-binding fragments thereof that specifically bind to BCMA according to the present invention have the following characteristics: (1) the property of binding to BCMA, such as human BCMA, cynomolgus monkey BCMA, and mouse BCMA, with high affinity, e.g., a binding K between the anti-BCMA antibody, or antigen-binding fragment thereof, and BCMA, as measured by a ForteBio kinetic binding assay; D is about 10 -9 M~about 10 -12 M, (2) the ability to specifically bind to BCMA expressed on the cell surface; (3) The ability to exhibit ADCC cytotoxicity and killing effect against cells expressing BCMA; (4) The property of having an ADCP killing effect on cells expressing BCMA; (5) the ability to inhibit and suppress the growth of and / or kill cells expressing human BCMA, particularly multiple myeloma cells; and (6) The property of having an in vivo antitumor effect against BCMA-expressing tumors without any obvious toxicity or side effects; Has one or more.

[0006] In a first aspect, the present invention provides an antibody or antigen-binding fragment thereof that specifically binds to BCMA, comprising: (a) a variant having three CDRs in the amino acid sequence of a heavy chain variable region shown in SEQ ID NO: 27 and three CDRs in the amino acid sequence of a light chain variable region shown in SEQ ID NO: 36, or a variant having a single CDR or multiple CDRs with no more than two or one amino acid change per CDR region in each of the six CDR regions; (b) a variant having three CDRs in the amino acid sequence of the heavy chain variable region shown in SEQ ID NO: 45 and three CDRs in the amino acid sequence of the light chain variable region shown in SEQ ID NO: 54, or a variant having a single CDR or multiple CDRs with no more than two or one amino acid change per CDR region in each of the six CDR regions; (c) a variant having three CDRs in the amino acid sequence of the heavy chain variable region set forth in SEQ ID NO: 81 and three CDRs in the amino acid sequence of the light chain variable region set forth in SEQ ID NO: 90, or a variant having a single CDR or multiple CDRs with no more than two or one amino acid change per CDR region in each of the six CDR regions; or (d) a variant having three CDRs in the amino acid sequence of the heavy chain variable region set forth in SEQ ID NO: 99 and three CDRs in the amino acid sequence of the light chain variable region set forth in SEQ ID NO: 108, or a variant having a single CDR or multiple CDRs with no more than two or one amino acid change per CDR region in each of the six CDR regions; Including, wherein said amino acid alteration is an amino acid addition, deletion or substitution, and wherein said antibody or antigen-binding fragment is provided.

[0007] In some embodiments, an antibody or antigen-binding fragment thereof that specifically binds to BCMA according to the invention comprises a heavy chain variable region and a light chain variable region, wherein: (a) the heavy chain variable region comprises an HCDR1 as set forth in GSIVSSSYYWT (SEQ ID NO: 19), or a variant of said HCDR1 with not more than two amino acid changes or not more than one amino acid change, an HCDR2 as set forth in SISIAGSTYYNPSLKS (SEQ ID NO: 20), or a variant of said HCDR2 with not more than two amino acid changes or not more than one amino acid change, and an HCDR3 as set forth in ARDRGDTILDV (SEQ ID NO: 21), or a variant of said HCDR3 with not more than two amino acid changes or not more than one amino acid change, according to the Kabat numbering system; wherein the light chain variable region comprises an LCDR1 as set forth in Kabat numbering as follows: RASQSISRYLN (SEQ ID NO:28), or a variant of said LCDR1 having no more than two amino acid changes or no more than one amino acid change; an LCDR2 as set forth in AASSLQS (SEQ ID NO:29), or a variant of said LCDR2 having no more than two amino acid changes or no more than one amino acid change; and an LCDR3 as set forth in QQKYFDIT (SEQ ID NO:30), or a variant of said LCDR3 having no more than two amino acid changes or no more than one amino acid change; (b) the heavy chain variable region comprises an HCDR1 as set forth in GSIVSSSYYWT (SEQ ID NO: 37), or a variant of said HCDR1 with not more than two amino acid changes or not more than one amino acid change, an HCDR2 as set forth in SISIAGSTYYNPSLKS (SEQ ID NO: 38), or a variant of said HCDR2 with not more than two amino acid changes or not more than one amino acid change, and an HCDR3 as set forth in ARDRGDQILDV (SEQ ID NO: 39), or a variant of said HCDR3 with not more than two amino acid changes or not more than one amino acid change, according to the Kabat numbering system; wherein the light chain variable region comprises an LCDR1 as set forth in Kabat numbering as follows: RASQSISRYLN (SEQ ID NO: 46), or a variant of said LCDR1 having no more than two amino acid changes or no more than one amino acid change; an LCDR2 as set forth in AASSLQS (SEQ ID NO: 47), or a variant of said LCDR2 having no more than two amino acid changes or no more than one amino acid change; and an LCDR3 as set forth in QQKYFDIT (SEQ ID NO: 48), or a variant of said LCDR3 having no more than two amino acid changes or no more than one amino acid change; (c) the heavy chain variable region comprises an HCDR1 as set forth in GTFSNDXIS (SEQ ID NO: 73), or a variant of said HCDR1 having not more than two amino acid changes or not more than one amino acid change, an HCDR2 as set forth in VIIPIFGIANYAQKFQG (SEQ ID NO: 74), or a variant of said HCDR2 having not more than two amino acid changes or not more than one amino acid change, and an HCDR3 as set forth in ARGRGYYSSWLLDI (SEQ ID NO: 75), or a variant of said HCDR3 having not more than two amino acid changes or not more than one amino acid change, according to the Kabat numbering system; the light chain variable region comprises an LCDR1 as set forth in the Kabat numbering of QASQDITNYLN (SEQ ID NO: 82), or a variant of said LCDR1 with no more than two amino acid changes or no more than one amino acid change, an LCDR2 as set forth in the Kabat numbering of DASNLET (SEQ ID NO: 83), or a variant of said LCDR2 with no more than two amino acid changes or no more than one amino acid change, and an LCDR3 as set forth in the Kabat numbering of QQAFDLIT (SEQ ID NO: 84), or a variant of said LCDR3 with no more than two amino acid changes or no more than one amino acid change; (d) the heavy chain variable region comprises an HCDR1 as set forth in GTFSNDXIS (SEQ ID NO: 91), or a variant of said HCDR1 having not more than two amino acid changes or not more than one amino acid change, an HCDR2 as set forth in VIIPIFGIANYAQKFQG (SEQ ID NO: 92), or a variant of said HCDR2 having not more than two amino acid changes or not more than one amino acid change, according to the Kabat numbering, and an HCDR3 as set forth in ARGRGYYSSWLHDI (SEQ ID NO: 93), or a variant of said HCDR3 having not more than two amino acid changes or not more than one amino acid change. the light chain variable region comprises an LCDR1 as set forth in Kabat numbering, QASQDITNYLN (SEQ ID NO: 100), or a variant of said LCDR1 with no more than two amino acid changes or no more than one amino acid change; an LCDR2 as set forth in DASNLET (SEQ ID NO: 101), or a variant of said LCDR2 with no more than two amino acid changes or no more than one amino acid change; and an LCDR3 as set forth in QQAFDLIT (SEQ ID NO: 102), or a variant of said LCDR3 with no more than two amino acid changes or no more than one amino acid change; Here, the amino acid change is an amino acid addition, deletion or substitution.

[0008] In some embodiments, an antibody or antigen-binding fragment thereof that specifically binds to BCMA according to the invention comprises a heavy chain variable region and a light chain variable region, (a) the heavy chain variable region comprises an HCDR1 represented by GSIVSSSYYWT (SEQ ID NO: 19), an HCDR2 represented by SISIAGSTYYNPSLKS (SEQ ID NO: 20), and an HCDR3 represented by ARDRGDTILDV (SEQ ID NO: 21); and the light chain variable region comprises an LCDR1 represented by RASQSISRYLN (SEQ ID NO: 28), an LCDR2 represented by AASSLQS (SEQ ID NO: 29), and an LCDR3 represented by QQKYFDIT (SEQ ID NO: 30); (b) the heavy chain variable region comprises an HCDR1 represented by GSIVSSSYYWT (SEQ ID NO: 37), an HCDR2 represented by SISIAGSTYYNPSLKS (SEQ ID NO: 38), and an HCDR3 represented by ARDRGDQILDV (SEQ ID NO: 39); and the light chain variable region comprises an LCDR1 represented by RASQSISRYLN (SEQ ID NO: 46), an LCDR2 represented by AASSLQS (SEQ ID NO: 47), and an LCDR3 represented by QQKYFDIT (SEQ ID NO: 48); (c) the heavy chain variable region comprises an HCDR1 represented by GTFSNDXIS (SEQ ID NO: 73), an HCDR2 represented by VIIPIFGIANYAQKFQG (SEQ ID NO: 74), and an HCDR3 represented by ARGYYSSWLLDI (SEQ ID NO: 75); and the light chain variable region comprises an LCDR1 represented by QASQDITNYLN (SEQ ID NO: 82), an LCDR2 represented by DASNLET (SEQ ID NO: 83), and an LCDR3 represented by QQAFDLIT (SEQ ID NO: 84); or (d) the heavy chain variable region comprises an HCDR1 represented by GTFSNDXIS (sequence number 91), an HCDR2 represented by VIIPIFGIANYAQKFQG (sequence number 92), and an HCDR3 represented by ARGRGYYSSWLHDI (sequence number 93), and the light chain variable region comprises an LCDR1 represented by QASQDITNYLN (sequence number 100), an LCDR2 represented by DASNLET (sequence number 101), and an LCDR3 represented by QQAFDLIT (sequence number 102).

[0009] In some embodiments, an antibody or antigen-binding fragment thereof that specifically binds to BCMA according to the invention comprises a heavy chain variable region and a light chain variable region, (a) the heavy chain variable region comprises a sequence of SEQ ID NO:27, or a sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto, and the light chain variable region comprises a sequence of SEQ ID NO:36, or a sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto; (b) the heavy chain variable region comprises a sequence of SEQ ID NO: 45, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto, and the light chain variable region comprises a sequence of SEQ ID NO: 54, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto; (c) the heavy chain variable region comprises a sequence of SEQ ID NO: 81, or a sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto, and the light chain variable region comprises a sequence of SEQ ID NO: 90, or a sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto; or (d) the heavy chain variable region comprises a sequence of SEQ ID NO: 99, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto, and the light chain variable region comprises a sequence of SEQ ID NO: 108, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto.

[0010] In some embodiments, an antibody or antigen-binding fragment thereof that specifically binds to BCMA according to the invention comprises a heavy chain variable region and a light chain variable region, wherein the antibody or antigen-binding fragment thereof comprises: (a) a heavy chain variable region set forth in SEQ ID NO: 27 and a light chain variable region set forth in SEQ ID NO: 36; (b) a heavy chain variable region set forth in SEQ ID NO: 45 and a light chain variable region set forth in SEQ ID NO: 54; (c) a heavy chain variable region set forth in SEQ ID NO: 81 and a light chain variable region set forth in SEQ ID NO: 90; or (d) a heavy chain variable region set forth in SEQ ID NO: 99 and a light chain variable region set forth in SEQ ID NO: 108; Includes.

[0011] In some embodiments, an antibody or antigen-binding fragment thereof that specifically binds to BCMA according to the invention is an IgG1, IgG2, IgG3 or IgG4 antibody, optionally an IgG1 or IgG4 antibody, optionally an IgG1 antibody. In some embodiments, the antigen-binding fragment is a Fab, Fab', F(ab')2, Fv, single chain Fv, single chain Fab or diabody.

[0012] In some embodiments, the antibody or antigen-binding fragment thereof that specifically binds to BCMA according to the invention further comprises a mutated Fc domain, where the amino acid at position P329 according to EU numbering is mutated to glycine (G) and the mutated Fc domain has reduced Fcγ receptor binding compared to Fcγ receptor binding of the non-mutated parent antibody Fc domain; for example, the mutated Fc domain is a mutated Fc domain of an IgG1, IgG2, IgG3 or IgG4 antibody; preferably, the mutated Fc domain is a mutated Fc domain of an IgG1 or IgG4 antibody; more preferably, the mutated Fc domain is a mutated Fc domain of an IgG1 antibody;

[0013] For example, the antibody or antigen-binding fragment thereof comprises a heavy chain constant region sequence set forth in SEQ ID NO: 111, or a sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto and an amino acid at position P329 according to EU numbering mutated with G;

[0014] For example, the antibody or antigen-binding fragment thereof comprises a heavy chain constant region sequence set forth in SEQ ID NO:111, or a sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto and an amino acid at position P329 according to EU numbering mutated with a G; and a light chain constant region sequence set forth in SEQ ID NO:112, or a sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto;

[0015] For example, the antibody or antigen-binding fragment thereof comprises the heavy chain constant region sequence shown in SEQ ID NO:111 and the light chain constant region sequence shown in SEQ ID NO:112.

[0016] In a second aspect, the invention provides a nucleic acid encoding an antibody of the first aspect of the invention, a vector comprising a nucleic acid encoding said antibody, a host cell comprising said nucleic acid molecule or vector, and a method of preparing said antibody, comprising culturing a host cell into which an expression vector for a nucleic acid encoding an antibody or antigen-binding fragment thereof that specifically binds to a BCMA molecule according to the first aspect of the invention has been introduced under conditions suitable for expression of a nucleic acid encoding an antibody or antigen-binding fragment thereof that specifically binds to a BCMA molecule according to the first aspect of the invention, and isolating said antibody or antigen-binding fragment thereof, optionally further comprising recovering said antibody or antigen-binding fragment thereof that specifically binds to said BCMA molecule from said host cell. Preferably, said host cell is a prokaryotic or eukaryotic cell, more preferably selected from E. coli cells, yeast cells, mammalian cells or other cells suitable for the preparation of antibodies or antigen-binding fragments thereof, most preferably said host cell is a HEK293 cell or a CHO cell.

[0017] In a third aspect, the present invention relates to a conjugate, fusion or bispecific antibody comprising an anti-BCMA antibody or antigen-binding fragment thereof according to the first aspect of the invention.

[0018] In a fourth aspect, the present invention relates to a pharmaceutical composition comprising an anti-BCMA antibody or antigen-binding fragment thereof according to the first aspect of the invention, or a conjugate, fusion or bispecific antibody according to the third aspect of the invention, and optionally a pharma- ceutical acceptable carrier.

[0019] In a fifth aspect, the present invention relates to the use of an anti-BCMA antibody or antigen-binding fragment thereof according to the first aspect of the invention, a conjugate, fusion or bispecific antibody according to the third aspect of the invention, or a pharmaceutical composition according to the fourth aspect of the invention, for the preparation of a medicament for preventing or treating a B cell related disease in a subject, wherein for example said B cell related disease is selected from the group consisting of B cell malignancies, plasma cell malignancies and autoimmune diseases, preferably multiple myeloma, non-Hodgkin's lymphoma, B cell proliferation of undetermined grade, lymphomatoid granulomatosis, post-transplant lymphoproliferative disorders, immunomodulatory disorders, rheumatoid arthritis, myasthenia gravis, idiopathic ... and wherein the B cell associated disease is selected from the group consisting of chronic thrombocytopenic purpura, antiphospholipid syndrome, Chagas' disease, Graves' disease, Wegener's granulomatosis, polyarteritis nodosa, Sjogren's syndrome, pemphigus vulgaris, scleroderma, multiple sclerosis, ANCA-associated vasculitis, Goodpasture's syndrome, Kawasaki's disease, autoimmune hemolytic anemia, and rapidly progressive glomerulonephritis, heavy chain disease, primary or immune cell-associated amyloidosis, or monoclonal gammopathy of undetermined significance, preferably wherein said B cell associated disease is a B cell malignancy, more preferably multiple myeloma (MM) or non-Hodgkin's lymphoma (NHL).

[0020] In a sixth aspect, the present invention provides a kit for detecting BCMA in a sample, said kit comprising an anti-BCMA antibody or antigen-binding fragment thereof according to the first aspect of the invention and comprising the following steps: (a) contacting a sample with an anti-BCMA antibody or antigen-binding fragment thereof of the first aspect of the invention; and (b) detecting the formation of a complex between said anti-BCMA antibody, or antigen-binding fragment thereof, and BCMA, optionally wherein said anti-BCMA antibody, or antigen-binding fragment thereof, is detectably labeled. [Brief description of the drawings]

[0021] Preferred embodiments of the invention, which are described in detail below, are better understood when read in conjunction with the following drawings: For the purposes of illustrating the invention, there are shown in the drawings embodiments which are presently preferred, but it should be understood that the invention is not limited to the precise arrangements and instrumentalities of the embodiments shown in the drawings. [Figure 1] 1 shows that the ADI-38497 antibody binds only to H929 cells expressing the BCMA antigen, but does not bind to BCMA-KO-H929 cells in which the BCMA gene has been knocked out. [Figure 2A] FIG. 1 shows a schematic diagram of a method for measuring antibody affinity using surface plasmon resonance (SPR). [Figure 2B] 1 shows spectra measuring representative affinity of ADI-38497PG antibody to recombinant human, cynomolgus monkey, mouse, rat and rabbit BCMA proteins using SPR. [Figure 2C] Figure 2 shows the binding ability of the P329G BCMA antibody to CHO-GS cells stably expressing human, cynomolgus monkey and mouse BCMA. [Figure 2D] Figure 2 shows the binding activity of the P329G BCMA antibody to the BCMA-expressing positive multiple myeloma cell lines MM.1s, RPMI8226, U266, H929, L363 and AMO1. [Figure 3A] 1 shows the ability of ADI-38497WT and ADI-38497PG antibodies to mediate ADCC killing. [Figure 3B] 1 shows the ability of ADI-38497WT and ADI-38497PG antibodies to mediate ADCP killing. [Figure 3C] 1 shows the ability of the ADI-38497PG antibody to mediate lysis of target cells. [Figure 4A] 1 shows the results of a pharmacokinetic experiment of the ADI-38497PG antibody in mice. [Figure 4B] 1 shows the results of a pharmacokinetic experiment of the ADI-38497PG antibody in mice. [Figure 5A]1 shows the therapeutic effect of ADI-38497PG antibody in immunodeficient tumor-bearing mice subcutaneously inoculated with human H929 highly expressing BCMA tumor cells. [Figure 5B] 1 shows the weight change in immunodeficient tumor-bearing mice subcutaneously inoculated with human H929 highly expressing BCMA tumor cells and treated with ADI-38497PG antibody. [Figure 6A] 1 shows the antitumor efficacy of different doses of ADI-38497PG antibody in immunodeficient tumor-bearing mice inoculated with human H929-luc tumor cells via the tail vein. [Figure 6B] 1 shows changes in body weight in immunodeficient tumor-bearing mice inoculated with human H929-luc tumor cells via the tail vein and treated with ADI-38497PG antibody. [Figure 7A] 1 shows the therapeutic efficacy of ADI-38497PG antibody in immunodeficient tumor-bearing mice subcutaneously inoculated with human H929 tumor cells. [Figure 7B] 1 shows changes in body weight of mice treated with ADI-38497PG antibody in immunodeficient tumor-bearing mice subcutaneously inoculated with human H929 tumor cells. [Figure 7C] 1 shows the hematological and blood biochemistry results of mice treated with ADI-38497PG antibody in immunodeficient tumor-bearing mice subcutaneously inoculated with human H929 tumor cells. [Figure 7D] 1 shows the hematological and blood biochemistry results of mice treated with ADI-38497PG antibody in immunodeficient tumor-bearing mice subcutaneously inoculated with human H929 tumor cells. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Unless otherwise limited, all technical and scientific terms used herein have the meaning commonly understood by those skilled in the art. All publications, patent applications, patents or other references mentioned herein are incorporated by reference in their entirety. In addition, the materials, methods and examples described herein are merely illustrative and not limiting. Other features, objects and advantages of the present invention will become apparent from the specification and drawings, and from the appended claims.

[0023] I. Definition

[0024] The following definitions will be used to interpret the specification, and where appropriate, terms used in the singular may also include the plural and vice versa. It should be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0025] The term "about," when used in conjunction with a number or numerical value, is meant to cover a range of numbers or numerical values ​​that is 5% less than the number or numerical value specified as the lower limit and 5% more than the number or numerical value specified as the upper limit.

[0026] As used herein, the term "and / or" refers to any one of available options or two or more of available options.

[0027] As used herein, the terms "comprise" or "comprise" include cases consisting of the elements, integers, or steps mentioned, unless otherwise specified. For example, when an antibody variable region "comprising" a specific sequence is mentioned, it is intended to encompass an antibody variable region consisting of this specific sequence.

[0028] The terms "BCMA" and "B cell maturation antigen" may be used interchangeably and include human BCMA variants, isotypes, species homologues and analogues that have at least one of the same epitopes as BCMA (e.g., human BCMA). BCMA proteins can also include fragments of BCMA, such as the extracellular domain and fragments of the extracellular domain, for example fragments that retain the ability to bind to any of the antibodies of the invention.

[0029] As used herein, the terms "BCMA antibody", "antibody against BCMA", "antibody that specifically binds to BCMA", "antibody that specifically targets BCMA" and "antibody that specifically recognises BCMA" may be used interchangeably and refer to an antibody that is capable of specifically binding to B-cell maturation antigen (BCMA).

[0030] The term "antibody" is used in the broadest sense in this application to mean a protein that contains an antigen-binding site, and includes natural and artificial antibodies of various structures, including, but not limited to, monoclonal antibodies, polyclonal antibodies, multispecific antibodies (e.g., bispecific antibodies), single chain antibodies, complete antibodies and antibody fragments. Preferably, the antibodies of the present invention are single domain antibodies or heavy chain antibodies.

[0031] "Antibody fragment" or "antigen-binding fragment" may be used interchangeably herein and refer to a molecule distinct from an intact antibody that contains a portion of an intact antibody and binds to the antigen to which the intact antibody binds. Examples of antibody fragments include, but are not limited to, Fab, Fab', F(ab')2, Fv, single-chain Fv, single-chain Fab, or diabody.

[0032] An antibody that exhibits the same or similar binding affinity and / or specificity as a reference antibody refers to an antibody that may have at least 50%, 60%, 70%, 80%, 90% or 95% or more of the binding affinity and / or specificity of the reference antibody, which may be measured by any method of measuring binding affinity and / or specificity known in the art.

[0033] "Complementarity determining regions", "CDR regions" or "CDRs" are regions in an antibody variable domain that are hypervariable in sequence and form structurally determined loops ("hypervariable loops") and / or contain antigen contact residues ("antigen contact points"). CDRs are primarily responsible for binding to antigen epitopes. The CDRs of the heavy chain are usually referred to as CDR1, CDR2 and CDR3, numbered sequentially from the N-terminus. For a given heavy chain variable region amino acid sequence, the precise amino acid sequence boundaries of each CDR can be determined by any one or a combination of a number of known antibody CDR assignment systems, including, for example, the Chothia system based on the three-dimensional structure of the antibody and the topology of the CDR loops (Chothia et al., (1989) Nature 342:877-883; Al-Lazikani et al., "Standard conformations for the canonical structures of immunoglobulins", Journal of Molecular Biology, 273, 927-948 (1997)), the Kabat system based on the variability of antibody sequences (Kabat et al., Sequences of Proteins of Immunological Interest, 4th edition, USDepartment of Health and Human Services, National Institutes of Health (1987)), the AbM (University of Bath), Contact (University College London), and the International ImMunoGeneTics (ImmunoGeneTics). The North CDR definition is based on affinity propagation clustering, which utilizes the IMGT database (http: / / imgt.cines.fr / ) and a large number of crystal structures.

[0034] Unless otherwise specified, in the present invention, the term "CDR" or "CDR sequence" covers a CDR sequence determined by any one of the above methods.

[0035] A CDR may be determined by having the same Kabat numbering position as a reference CDR sequence (e.g., any one of the exemplary CDRs of the present invention). In the present invention, when referring to an antibody variable region and a specific CDR sequence (including heavy chain variable region residues), the numbering position according to the Kabat numbering system is referred to.

[0036] Although CDRs differ between antibodies, there are a limited number of amino acid positions in the CDRs that are directly involved in binding to the antigen. By using at least two of the Kabat, Chothia, AbM and Contact methods, the minimum overlapping region can be determined, thereby providing a "minimum binding unit" for binding to the antigen. The minimum binding unit may be a subpart of one of the CDRs. As known to those skilled in the art, the structure of the antibody and protein folding can determine the residues of the remaining part of the CDR sequence. Thus, the present invention contemplates variants of any of the CDRs provided herein. For example, in a variant of one CDR, the amino acid residues of the minimum binding unit may be left as they are, but the remaining CDR residues defined based on Kabat, Chothia or AbM may be replaced with conservative amino acid residues.

[0037] A "humanized" antibody refers to a chimeric antibody that comprises amino acid residues from non-human CDRs and amino acid residues from human FRs. In some embodiments, all or essentially all of the CDRs (e.g., CDRs) in a humanized antibody correspond to those of a non-human antibody, and all or essentially all of the FRs correspond to those of a human antibody. A humanized antibody may optionally contain at least a portion of an antibody constant region derived from a human antibody. A "humanized form" of an antibody (e.g., a non-human antibody) refers to an antibody that has been humanized.

[0038] "Human antibody" refers to an antibody having an amino acid sequence that corresponds to the amino acid sequence of an antibody produced by a human or human cell, or of non-human origin, using a human antibody library or other human antibody coding sequence. This definition of a human antibody specifically excludes humanized antibodies that contain non-human antigen-binding residues.

[0039] The term "Fc region" is used herein to define the C-terminal region of an immunoglobulin heavy chain, said region including at least a portion of the constant region. The term includes native sequence Fc regions and variant Fc regions. In some embodiments, the Fc region of a human IgG heavy chain extends from Cys226 or Pro230 to the carbonyl terminus of the heavy chain. However, the C-terminal lysine (Lys447) of the Fc region may or may not be present. Unless otherwise specified, the numbering of amino acid residues in the Fc region or constant region is according to the EU numbering system, also called the EU index, as described, for example, in Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, MD, 1991.

[0040] In some embodiments, the Fc region of an immunoglobulin comprises two constant domains, namely, CH2 and CH3, and in some further embodiments, the Fc region of an immunoglobulin comprises three constant domains, namely, CH2, CH3 and CH4.

[0041] Binding of IgG to Fcγ receptors or C1q depends on residues located in the hinge region and the CH2 domain. Two regions of the CH2 domain are crucial for binding of FcγR and complement C1q and have unique sequences in IgG2 and IgG4. Substitution of residues at positions 233-236 in human IgG1 and IgG2, and at positions 327, 330, and 331 in human IgG4, have been shown to significantly reduce ADCC and CDC activity (Armour et al., Eur. J. Immunol. 29(8), 1999, 2613-2624; Shields et al., J. Biol. Chem. 276(9), 2001, 6591-6604).

[0042] Similar terms such as "functional Fc region" and "functional Fc region" may be used interchangeably and refer to an Fc region that has an effector function of a wild-type Fc region.

[0043] Similar terms such as "mutated Fc region," "Fc mutant," "Fc region with mutation," "mutated Fc region," "Fc region mutant," "Fc mutant," "mutant Fc region" and "mutant Fc region" may be used interchangeably and refer to an Fc region that contains at least one amino acid modification that distinguishes it from a native sequence / wild-type Fc region.

[0044] In some embodiments, the variant Fc region comprises an amino acid sequence that differs from that of a native sequence Fc region by one or more amino acid substitutions, deletions, or additions, hi some embodiments, the variant Fc region has at least one amino acid substitution compared to a wild-type IgG Fc region, wherein the at least one amino acid substitution is a substitution of the amino acid at position P329 according to EU numbering with glycine (G).

[0045] "Fc receptor" or "FcR" refers to a molecule that binds to an antibody Fc region. In some embodiments, the FcR is a naturally occurring human FcR. In some embodiments, the FcR is a receptor that binds to IgG antibodies, i.e., FcγR, and includes the three receptors FcγRI (CD64), FcγRII (CD32), and FcγRIII (CD16), as well as allelic variants and alternatively spliced ​​forms of these receptors. FcγRII receptors include FcγRIIA and FcγRIIB, and FcγRIII receptors include FcγRIIIA and FcγRIIIB.

[0046] The term "effector function" refers to those biological activities associated with the immunoglobulin Fc region that vary depending on the immunoglobulin isotype. Examples of immunoglobulin effector functions include Fc receptor binding, antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), cytokine secretion, immune complex-mediated antigen uptake by antigen-presenting cells, C1q binding and complement-dependent cytotoxicity (CDC), downregulation of cell surface receptors (such as B cell receptors) and activation of B cells.

[0047] The term "antibody-dependent cell-mediated cytotoxicity (ADCC)" refers to one of the primary mechanisms by which certain cytotoxic effector cells, such as natural killer (NK) cells, mediate the killing of target cells and foreign host cells. In some embodiments, the antibodies of the invention provide antibody-dependent cellular cytotoxicity of T lymphocytes and enhance the antibody-dependent cellular cytotoxicity of NK cells.

[0048] The term "antibody-dependent cellular phagocytosis (ADCP)" refers to a cellular response in which an antibody bound to a target cell binds to FcγRIIIa on the surface of the macrophage, inducing macrophage activation, which results in the target cell being internalized and degraded by acidification in the phagosome. ADCP can also be mediated by FcγRIIa and FcγRI, but to a relatively small extent.

[0049] The term "complement-dependent cytotoxicity (CDC)" refers to the lysis of target cells in the presence of complement. The complement system is a part of the innate immune system that consists of a series of proteins. The proteins of the complement system, called "complements" and represented by the abbreviations C1, C2, C3, etc., are a group of heat-labile proteins present in serum and tissue fluids of humans and vertebrates that have enzymatic activity after activation. C1q is the first component of the complement-dependent cytotoxicity (CDC) pathway and can bind to six antibodies, but binding to two IgGs is sufficient to activate the complement cascade. Activation of the classical complement pathway is initiated by the binding of the first component of the complement system (C1q) to an antibody (of the appropriate subclass) that binds to the relevant antigen, activating a series of complement cascade reactions that result in the formation of a pore in the target cell membrane, thereby causing target cell death. To assess complement activation, a CDC assay can be performed, for example, as described in Gazzano-Santoro et al., J. Immunol. Methods 202:163 (1996).

[0050] The term "variable region" or "variable domain" refers to the domain of an antibody heavy or light chain that is involved in binding the antibody to an antigen. The variable domains of the heavy and light chains of natural antibodies generally have a similar structure, in which each domain contains four conserved framework regions (FR) and three complementarity determining regions (CDR). (See, for example, Kindt et al., Kuby Immunology, 6 th ed., WH Freeman and Co. p91 (2007). A single VH or VL domain may be sufficient to confer antigen-binding specificity.

[0051] As used herein, the terms "binding" or "specifically binding" mean that the binding action is selective for the antigen and can be distinguished from unwanted or non-specific interactions. The binding ability of an antibody to a specific antigen can be measured by enzyme-linked immunosorbent assay (ELISA), SPR, biolayer interferometry, or other conventional binding assays known in the art.

[0052] A "conjugate" is an antibody linked to one or more other substances, including, but not limited to, a cytotoxic agent or a label.

[0053] The term "suppression" or "inhibition" refers to decreasing a particular parameter (e.g., activity) of a given molecule. For example, the term includes substances that inhibit the activity of a given molecule (e.g., BCMA) by at least 5%, 10%, 20%, 30%, 40% or more. Thus, an inhibitory effect is not necessarily 100%.

[0054] The terms "individual" or "subject" can be used interchangeably and include mammals. Mammals include, but are not limited to, domestic animals (e.g., cows, goats, cats, dogs and horses), primates (e.g., humans and non-human primates such as monkeys), rabbits, and rodents (e.g., mice and rats). In particular, an individual or subject is a human.

[0055] The terms "tumor" and "cancer" are used interchangeably herein and include solid and liquid tumors.

[0056] The terms "cancer" and "cancerous" refer to a physiological disorder in mammals in which cell growth is unregulated.

[0057] The term "tumor" refers to all neoplastic cell growth and proliferation, whether malignant or benign, and all pre-cancerous and cancerous cells or tissues. The terms "cancer," "cancerous," and "tumor" are not mutually exclusive when referred to herein.

[0058] The term "label" as used herein refers to a compound or composition that is directly or indirectly bound or fused to a reagent (e.g., an antibody) and facilitates detection by the reagent to which it is bound or fused. The label can be detectable itself (e.g., a radioisotope label or a fluorescent label) or, when labeled by enzyme catalysis, can catalyze a chemical modification of a substrate compound or composition that is detectable. The term includes direct labeling of a probe or antibody by coupling (i.e., physically linking) a detectable substance to the probe or antibody, and indirect labeling of a probe or antibody by reaction with another reagent that is directly labeled. Examples of indirect labeling include detection of a primary antibody by a fluorescently labeled secondary antibody, and the use of end-labeling of a DNA probe with biotin that is detectable with a fluorescently labeled streptavidin protein.

[0059] An "isolated" antibody refers to one that has been separated from the components of its natural environment. In some embodiments, the antibody is purified to greater than 95% or 99% purity, as determined, for example, by electrophoresis (e.g., SDS-PAGE, isoelectric focusing (IEF), capillary electrophoresis) or chromatography (e.g., ion exchange or reverse-phase HPLC). For a review of methods for assessing antibody purity, see, for example, Flatman et al., J. Chromatogr. B848:79-87 (2007).

[0060] An "isolated" nucleic acid refers to a nucleic acid molecule that is separated from a component of its natural environment. An isolated nucleic acid includes a nucleic acid molecule that is generally contained within a cell that contains the nucleic acid molecule, but the nucleic acid molecule is present extrachromosomally or at a chromosomal location that is different from its natural chromosomal location. An "isolated nucleic acid encoding a BCMA antibody" refers to one or more nucleic acid molecules that encode a BCMA antibody chain or fragment thereof, and includes such nucleic acid molecules in a single vector or separate vectors, and such nucleic acid molecules present in one or more locations within a host cell.

[0061] The sequence identity between sequences is calculated as follows.

[0062] To determine the percentage identity of two amino acid sequences or two nucleic acid sequences, the sequences are aligned for optimal comparison (e.g., gaps may be introduced in one or both of the first and second amino acid or nucleic acid sequences for optimal alignment, or non-homologous sequences may be discarded for comparison). In a preferred embodiment, the length of the reference sequence aligned for comparison is at least 30%, preferably at least 40%, more preferably at least 50%, 60%, even more preferably at least 70%, 80%, 90%, 100% of the length of the reference sequence. The amino acid residues or nucleotides at the corresponding amino acid or nucleotide positions are then compared. If a position in the first sequence is occupied by the same amino acid residue or nucleotide at the corresponding position in the second sequence, the molecules are identical at this position.

[0063] A mathematical algorithm can realize the sequence comparison between two sequences and the calculation of the identity percentage. In one preferred embodiment, the identity percentage between two amino acid sequences is determined by the Needlema and Wunsch ((1970) J. Mol. Biol. 48: 444-453) algorithm integrated in the GAP program of the GCG software package (available at http: / / www.gcg.com) using a Blossum 62 matrix or a PAM250 matrix, and a gap weight of 16, 14, 12, 10, 8, 6 or 4 and a length weight of 1, 2, 3, 4, 5 or 6. In another preferred embodiment, the identity percentage between two nucleotide sequences is determined by the GAP program of the GCG software package (available at http: / / www.gcg.com) using a NWSgapdna.CMP matrix, and a gap weight of 40, 50, 60, 70 or 80 and a length weight of 1, 2, 3, 4, 5 or 6. A particularly preferred set of parameters (and the one that should be used unless otherwise noted) employs a Blossum 62 scoring matrix with a gap penalty of 12, a gap extension penalty of 4, and a frameshift gap penalty of 5.

[0064] The percentage identity between two amino acid or nucleotide sequences may also be determined using the E. Meyers and W. Miller algorithm ((1989) CABIOS, 4:11-17) integrated into the ALIGN program (version 2.0) using a PAM120 weighted remainder table, a gap length penalty of 12, and a gap penalty of 4.

[0065] Additionally or alternatively, the nucleic acid and protein sequences described herein can be used as "query sequences" to perform a search against public databases, e.g., to identify other family member sequences or related sequences.

[0066] The terms "amino acid change" and "amino acid modification" may be used interchangeably and refer to addition, deletion, substitution and other modifications of amino acids. Any combination of addition, deletion, substitution and other modifications of amino acids may be made, provided that the final polypeptide sequence has the desired properties. In some embodiments, the amino acid substitution of an antibody results in a decrease in the binding of the antibody to an Fc receptor. Non-conservative amino acid substitutions, i.e., the replacement of one amino acid with another amino acid having different structure and / or chemical properties, are particularly preferred, for example to modify the binding properties of the Fc region. Amino acid substitutions include substitutions with unnatural amino acids or natural amino acid derivatives of the 20 standard amino acids (e.g., 4-hydroxyproline, 3-methylhistidine, ornithine, homoserine, 5-hydroxylysine). Amino acid changes may be made using genetic or chemical methods known in the art. Genetic methods may include site-directed mutagenesis, PCR, gene synthesis, and the like. Methods of modifying amino acid side groups by methods other than genetic engineering (e.g., chemical modification) may be useful. Various names may be used herein to refer to the same amino acid change. For example, a proline to glycine substitution at position 329 of the Fc domain is 329G, G329, G 329 , P329G Pro329Gly, or abbreviated as "PG."

[0067] The term "conservative sequence modification", "conservative sequence change" refers to an amino acid modification or change that does not significantly affect or change the binding properties of the antibody or antibody fragment containing the amino acid sequence. Such conservative modifications include amino acid substitutions, additions and deletions. Modifications can be introduced into the antibody or antibody fragment of the present invention by standard techniques known in the art, such as site-directed mutagenesis and PCR-mediated mutagenesis. Conservative substitutions are those in which an amino acid residue is replaced with an amino acid residue having a similar side chain. Families of amino acid residues having similar side chains have been defined in the art. These families include amino acids with basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine, tryptophan), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine), β-side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine).

[0068] The term "pharmaceutical composition" refers to a composition that is present in a form that effectively activates the biological activity of the active ingredient contained therein, and does not contain additional ingredients that are unacceptably toxic to a subject to which the composition is administered.

[0069] The term "pharmaceutical acceptable carrier" refers to a diluent, adjuvant (eg, Freund's adjuvant (complete or incomplete)), excipient, buffer, stabilizer, or the like, with which an active substance is administered.

[0070] The term "BCMA associated disease" refers to any disease caused by, exacerbated by, or otherwise associated with increased expression or activity of BCMA.

[0071] As used herein, "treatment" refers to relieving, interrupting, slowing, ameliorating, arresting, reducing, or reversing existing symptoms, conditions, symptoms, or progression or severity of a disease. Desired therapeutic effects include, but are not limited to, preventing the onset or recurrence of a disease, alleviating symptoms, reducing any direct or indirect pathological consequences of a disease, preventing metastasis, reducing the rate of disease progression, ameliorating or alleviating the disease state, and alleviating or improving prognosis. In some embodiments, the antibody molecules of the present invention are for delaying the onset of a disease or reducing the progression of a disease.

[0072] As used herein, "prevention" includes the inhibition of the onset or progression of a disease, condition, or symptom of a particular disease or condition. In some embodiments, subjects with a family history of cancer are candidates for a prevention program. In general, in the context of cancer, the term "prevention" refers to the administration of a drug before symptoms or symptoms of cancer arise, particularly before cancer occurs in subjects at risk of suffering from cancer.

[0073] The term "effective amount" refers to the amount or dosage of the antibody or composition of the present invention that, after administration to a patient in one or more doses, will produce the desired effect in a patient in need of treatment or prevention. The effective amount can be readily determined by the attending physician, who is skilled in the art, taking into consideration various factors, such as, for example, the mammalian species, body weight, age and general health condition, the specific disease, the extent or severity of the disease, the response of the individual patient, the specific antibody administered, the mode of administration, the bioavailability characteristics of the administered formulation, the administration schedule selected, and the application of any combination therapy.

[0074] A "therapeutically effective amount" refers to an amount that effectively achieves a desired therapeutic result at a required dosage for a required period of time. A therapeutically effective amount of an antibody or antibody fragment or composition thereof can vary depending on various factors, such as, for example, the disease state, the age, sex and weight of the individual, and the ability of the antibody or antibody portion to elicit a desired response in the individual. A therapeutically effective amount may be an amount in which any toxic or adverse effects of the antibody or antibody fragment or composition thereof are not exceeded by the beneficial therapeutic effect. For untreated subjects, a "therapeutically effective amount" preferably results in at least about 20%, more preferably at least about 40%, even more preferably at least about 50%, 60% or 70%, and even more preferably at least about 80% or 90% inhibition of a measurable parameter (e.g., tumor growth rate, tumor volume, etc.). The ability of a compound to inhibit a measurable parameter (e.g., cancer) can be evaluated in an animal model system that demonstrates efficacy in human tumors.

[0075] A "prophylactically effective amount" refers to an amount to effectively achieve a desired prophylactic result at a necessary dosage for a necessary period of time. Generally, the prophylactically effective amount will be less than the therapeutically effective amount, since a prophylactic dose is administered prior to or at an earlier stage of disease in a subject.

[0076] The term "vector" as used herein in reference to a nucleic acid refers to a nucleic acid molecule capable of propagating another nucleic acid to which it is linked. The term includes vectors that are self-replicating nucleic acid structures and vectors that are integrated into the genome of a host cell into which they are introduced. Some vectors are capable of directing the expression of a nucleic acid that is operatively linked to them. Such vectors are referred to herein as "expression vectors."

[0077] The term "host cell" refers to a cell into which an exogenous polynucleotide has already been introduced, including the progeny of such a cell. Host cells include "transformants" and "transformed cells", including cells transformed from the original and their progeny derived therefrom, regardless of the number of passages. Progeny may not be identical to the parent cell in nucleic acid content and may contain mutations. As used herein, includes mutant progeny having the same function or biological activity as screened or selected from the original transformed cell. Host cells may be any type of cell line that can be used to produce the antibody molecules of the invention, including eukaryotic cells such as mammalian cells, insect cells, yeast cells, and prokaryotic cells such as E. coli cells. Host cells include cultured cells, including cells within transgenic animals, transgenic plants, or cultured plant or animal tissues.

[0078] "Subject / patient sample" refers to a collection of cells, tissues, or bodily fluids obtained from a patient or subject. The source of the tissue or cell sample may be solid tissue, such as fresh, frozen, and / or preserved organ or tissue samples, biopsy or aspirate samples, blood or any blood component, bodily fluids, such as cerebrospinal fluid, amniotic fluid (amniotic fluid), peritoneal fluid (ascites) or interstitial fluid, or cells from any stage of pregnancy or development in a subject. Tissue samples may contain compounds that are not naturally mixed with tissue in nature, such as preservatives, anticoagulants, buffers, fixatives, nutrients, antibiotics, etc. Non-limiting examples of tumor samples referred to herein include tumor biopsy samples, aspirates, bronchoalveolar lavage fluid, pleural fluid (pleural effusion), sputum, urine, surgical specimens, migratory tumor cells, serum, plasma, migratory plasma proteins, ascites, primary cell cultures or cell lines derived from tumors or exhibiting tumor-like properties, or archived tumor samples such as formalin-fixed or paraffin-embedded tumor samples or frozen tumor samples.

[0079] II. Antibodies that specifically bind to BCMA molecules of the invention and those containing variant Fc domains

[0080] The present invention provides antibodies that bind to BCMA with high target specificity and high affinity comprising a heavy chain variable region and a light chain variable region, wherein:

[0081] (a) the heavy chain variable region comprises an HCDR1 as set forth in GSIVSSSYYWT (SEQ ID NO: 19), or a variant of said HCDR1 with not more than two amino acid changes or not more than one amino acid change, an HCDR2 as set forth in SISIAGSTYYNPSLKS (SEQ ID NO: 20), or a variant of said HCDR2 with not more than two amino acid changes or not more than one amino acid change, and an HCDR3 as set forth in ARDRGDTILDV (SEQ ID NO: 21), or a variant of said HCDR3 with not more than two amino acid changes or not more than one amino acid change, according to the Kabat numbering system; wherein the light chain variable region comprises an LCDR1 as set forth in Kabat numbering as follows: RASQSISRYLN (SEQ ID NO:28), or a variant of said LCDR1 having no more than two amino acid changes or no more than one amino acid change; an LCDR2 as set forth in AASSLQS (SEQ ID NO:29), or a variant of said LCDR2 having no more than two amino acid changes or no more than one amino acid change; and an LCDR3 as set forth in QQKYFDIT (SEQ ID NO:30), or a variant of said LCDR3 having no more than two amino acid changes or no more than one amino acid change;

[0082] (b) the heavy chain variable region comprises an HCDR1 as set forth in GSIVSSSYYWT (SEQ ID NO: 37), or a variant of said HCDR1 with not more than two amino acid changes or not more than one amino acid change, an HCDR2 as set forth in SISIAGSTYYNPSLKS (SEQ ID NO: 38), or a variant of said HCDR2 with not more than two amino acid changes or not more than one amino acid change, and an HCDR3 as set forth in ARDRGDQILDV (SEQ ID NO: 39), or a variant of said HCDR3 with not more than two amino acid changes or not more than one amino acid change, according to the Kabat numbering system; wherein the light chain variable region comprises an LCDR1 as set forth in Kabat numbering as follows: RASQSISRYLN (SEQ ID NO: 46), or a variant of said LCDR1 having no more than two amino acid changes or no more than one amino acid change; an LCDR2 as set forth in AASSLQS (SEQ ID NO: 47), or a variant of said LCDR2 having no more than two amino acid changes or no more than one amino acid change; and an LCDR3 as set forth in QQKYFDIT (SEQ ID NO: 48), or a variant of said LCDR3 having no more than two amino acid changes or no more than one amino acid change;

[0083] (c) the heavy chain variable region comprises an HCDR1 as set forth in GTFSNDXIS (SEQ ID NO: 73), or a variant of said HCDR1 having not more than two amino acid changes or not more than one amino acid change, an HCDR2 as set forth in VIIPIFGIANYAQKFQG (SEQ ID NO: 74), or a variant of said HCDR2 having not more than two amino acid changes or not more than one amino acid change, and an HCDR3 as set forth in ARGRGYYSSWLLDI (SEQ ID NO: 75), or a variant of said HCDR3 having not more than two amino acid changes or not more than one amino acid change, according to the Kabat numbering system; the light chain variable region comprises an LCDR1 as set forth in the Kabat numbering of QASQDITNYLN (SEQ ID NO: 82), or a variant of said LCDR1 with no more than two amino acid changes or no more than one amino acid change, an LCDR2 as set forth in the Kabat numbering of DASNLET (SEQ ID NO: 83), or a variant of said LCDR2 with no more than two amino acid changes or no more than one amino acid change, and an LCDR3 as set forth in the Kabat numbering of QQAFDLIT (SEQ ID NO: 84), or a variant of said LCDR3 with no more than two amino acid changes or no more than one amino acid change;

[0084] (d) the heavy chain variable region comprises an HCDR1 as set forth in GTFSNDXIS (SEQ ID NO: 91), or a variant of said HCDR1 having not more than two amino acid changes or not more than one amino acid change, an HCDR2 as set forth in VIIPIFGIANYAQKFQG (SEQ ID NO: 92), or a variant of said HCDR2 having not more than two amino acid changes or not more than one amino acid change, according to the Kabat numbering, and an HCDR3 as set forth in ARGRGYYSSWLHDI (SEQ ID NO: 93), or a variant of said HCDR3 having not more than two amino acid changes or not more than one amino acid change. the light chain variable region comprises an LCDR1 as set forth in Kabat numbering, QASQDITNYLN (SEQ ID NO: 100), or a variant of said LCDR1 with no more than two amino acid changes or no more than one amino acid change; an LCDR2 as set forth in DASNLET (SEQ ID NO: 101), or a variant of said LCDR2 with no more than two amino acid changes or no more than one amino acid change; and an LCDR3 as set forth in QQAFDLIT (SEQ ID NO: 102), or a variant of said LCDR3 with no more than two amino acid changes or no more than one amino acid change;

[0085] Here, the amino acid change is an amino acid addition, deletion or substitution.

[0086] In some embodiments, antibodies that bind BCMA molecules according to the invention bind to mammalian BCMA, such as human, cynomolgus monkey, mouse, rat and rabbit BCMA.

[0087] In some embodiments, an antibody that binds a BCMA molecule according to the invention comprises a heavy chain variable region and a light chain variable region that specifically binds BCMA, wherein:

[0088] (a) the heavy chain variable region comprises a sequence of SEQ ID NO:27, or a sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto, and the light chain variable region comprises a sequence of SEQ ID NO:36, or a sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto;

[0089] (b) the heavy chain variable region comprises a sequence of SEQ ID NO: 45, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto, and the light chain variable region comprises a sequence of SEQ ID NO: 54, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto;

[0090] (c) the heavy chain variable region comprises a sequence of SEQ ID NO: 81, or a sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto, and the light chain variable region comprises a sequence of SEQ ID NO: 90, or a sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto; or

[0091] (d) the heavy chain variable region comprises a sequence of SEQ ID NO: 99, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto, and the light chain variable region comprises a sequence of SEQ ID NO: 108, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto;

[0092] Here, the amino acid changes in the sequences having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity are preferably amino acid substitutions, more preferably conservative amino acid substitutions, and preferably, the amino acid changes do not occur in the CDR regions.

[0093] In some embodiments an antibody that binds a BCMA molecule according to the invention is an IgG1, IgG2, IgG3 or IgG4 antibody, preferably an IgG1 or IgG4 antibody, more preferably an IgG1 antibody, such as a human IgG1 antibody.

[0094] In some embodiments, an antibody that binds to a BCMA molecule provided herein comprises a mutated Fc domain, where the amino acid at position P329 according to EU numbering is mutated to a glycine (G), and wherein the mutated Fc domain has reduced Fcγ receptor binding compared to Fcγ receptor binding of the non-mutated parent antibody Fc domain, e.g., the mutated Fc domain is a mutated Fc domain of an IgG1, IgG2, IgG3 or IgG4 antibody, preferably the mutated Fc domain is a mutated Fc domain of an IgG1 or IgG4 antibody, more preferably the mutated Fc domain is a mutated Fc domain of an IgG1 antibody, e.g. the mutated Fc domain is a mutated Fc domain of a human IgG1 antibody.

[0095] Antibodies containing the P329G mutant Fc domain bound to BCMA molecules are unable to exert antibody-dependent cellular cytotoxicity by binding to Fcγ receptors, nor are they able to exert antibody-dependent cellular phagocytosis (ADCP).

[0096] In some embodiments, antibodies that bind BCMA molecules according to the invention have the following characteristics: (1) the property of binding to BCMA, such as human BCMA, cynomolgus monkey BCMA, and mouse BCMA, with high affinity, e.g., a binding K between the anti-BCMA antibody, or antigen-binding fragment thereof, and BCMA, as measured by a ForteBio kinetic binding assay; D is about 10-9 M~about 10 -12 M,

[0097] (2) the ability to specifically bind to BCMA expressed on the cell surface; (3) The ability to exhibit ADCC cytotoxicity and killing effect against cells expressing BCMA; (4) The property of having an ADCP killing effect on cells expressing BCMA; (5) the ability to inhibit and suppress the growth of and / or kill cells expressing human BCMA, particularly multiple myeloma cells; and

[0098] (6) The property of having an in vivo antitumor effect against BCMA-expressing tumors without any obvious toxicity or side effects;

[0099] Has one or more. In some embodiments, the invention provides a nucleic acid encoding any of the above antibodies or fragments thereof or any of the chains thereof that bind to a BCMA molecule. In one embodiment, a vector comprising the above nucleic acid is provided. In one embodiment, the vector is an expression vector. In one embodiment, a host cell comprising the above nucleic acid or the above vector is provided. In one embodiment, the host cell is eukaryotic. In another embodiment, the host cell is selected from a yeast cell, a mammalian cell (e.g., a CHO cell or a HEK293 cell) or other cell suitable for the preparation of an antibody or antigen-binding fragment thereof. In another embodiment, the host cell is prokaryotic.

[0100] For example, the nucleic acid of the present invention includes a nucleic acid encoding an antibody that binds to a BCMA molecule of the present invention. In some embodiments, one or more vectors are provided that include the nucleic acid. In one embodiment, the vector is an expression vector, such as a eukaryotic expression vector. Vectors include, but are not limited to, viruses, plasmids, cosmids, lambda phages, or yeast artificial chromosomes (YACs). In one embodiment, the vector is a pcDNA3.4 expression vector.

[0101] Once the expression vector or DNA sequence for expression is prepared, the expression vector can be transfected or introduced into a suitable host cell. To this end, various techniques can be utilized, such as protoplast fusion, calcium phosphate co-precipitation, electroporation, retroviral transduction, viral transfection, particle gun, lipid-based transfection or other conventional techniques. In the case of protoplast fusion, the cells are cultured in culture medium and screened for appropriate activity. The methods and conditions for culturing the transfected cells produced and recovering the produced antibody molecules are known to those skilled in the art and can be modified or optimized according to the particular expression vector and mammalian host cell used, according to the methods described herein and known in the art.

[0102] Also, by introducing one or more selectable markers into the transfected host cells, cells in which the DNA has been stably introduced into their chromosomes can be selected. The markers can confer prototrophy to an auxotrophic host, resistance to biocides (e.g., antibiotics) or resistance to heavy metals (e.g., copper), etc. The selectable marker gene can be directly linked to the DNA sequence to be expressed or introduced into the same cell by co-transformation. Additional elements may be required for optimization of mRNA synthesis. These elements may include splicing signals, transcription promoters, enhancers, and termination signals.

[0103] In one embodiment, a host cell is provided that comprises a polynucleotide of the invention. In some embodiments, a host cell is provided that comprises an expression vector of the invention. In some embodiments, the host cell is selected from a yeast cell, a mammalian cell, or other cells suitable for preparing antibodies. Suitable host cells include prokaryotic microorganisms such as E. coli. The host cell may be a eukaryotic microorganism such as a filamentous fungus or yeast, or a variety of eukaryotic cells such as insect cells. Vertebrate cells may also be used as hosts. For example, mammalian cell lines modified to be suitable for suspension growth may be used. Examples of mammalian host cell lines that can be used include SV40 transformed monkey kidney CV1 line (COS-7), human embryonic kidney lines (HEK293 or 293F cells), baby hamster kidney cells (BHK), monkey kidney cells (CV1), African green monkey kidney cells (VERO-76), human cervical carcinoma cells (HELA), canine kidney cells (MDCK), buffalo rat liver cells (BRL 3A), human lung cells (W138), human liver cells (HepG2), Chinese hamster ovary cells (CHO cells), myeloma cell lines such as CHO-S cells, NSO cells, YO, NS0, P3X63 and Sp2 / 0. For a review of mammalian host cell lines suitable for protein production, see, for example, Yazaki & Wu, Methods in Molecular Biology, Vol. 248 (edited by BKC Lo, Humana Press, Totowa, NJ), p. 255-268 (2003). In a preferred embodiment, the host cell is a CHO cell or a HEK293 cell.

[0104] In one embodiment, the invention provides a method of preparing an antibody that binds a BCMA molecule (including a P329G mutant antibody), said method comprising culturing a host cell comprising a nucleic acid encoding an antibody that binds a BCMA molecule (including a P329G mutant antibody) or an expression vector comprising said nucleic acid under conditions suitable for expression of a nucleic acid encoding an antibody that binds said BCMA molecule (including a P329G mutant antibody), and optionally isolating said antibody that binds the BCMA molecule (including a P329G mutant antibody). In an embodiment, the method further comprises recovering the antibody that binds the BCMA molecule (including a P329G mutant antibody) from the host cell (or host cell medium).

[0105] Antibodies (including P329G mutant antibodies) that bind BCMA molecules of the invention prepared as described herein can be purified by known conventional techniques such as high performance liquid chromatography, ion exchange chromatography, gel electrophoresis, affinity chromatography, size exclusion chromatography, etc. The actual conditions for purifying a particular protein will also depend on factors such as net charge, hydrophobicity, hydrophilicity, etc., and will be apparent to those skilled in the art. The purity of antibodies (including P329G mutant antibodies) that bind BCMA molecules of the invention can be determined by any one of a variety of known analytical methods, including size exclusion chromatography, gel electrophoresis, high performance liquid chromatography, etc.

[0106] Antibodies that bind to BCMA molecules provided herein (including P329G mutant antibodies) can be identified, screened, or characterized for their physical / chemical characteristics and / or biological activity by various assays known in the art. In one aspect, antibodies that bind to BCMA molecules of the invention (including P329G mutant antibodies) are tested for their antigen binding activity by known methods, such as, for example, FACS, ELISA, or Western blotting. Binding to BCMA can be measured by methods known in the art, and exemplary methods are disclosed herein. In some embodiments, FACS is used to measure binding of antibodies that bind to BCMA molecules of the invention (including P329G mutant antibodies) to cell surface BCMA (e.g., human BCMA).

[0107] The present invention further provides assays for identifying antibodies (including P329G mutant antibodies) that bind to BCMA molecules and have biological activity. Biological activity may include, for example, ADCC activity, CDC activity, etc.

[0108] Cells used in any of the above in vitro assays include cell lines that naturally express BCMA or that have been modified to express BCMA, that is, cell lines that do not normally express BCMA but that express BCMA after DNA encoding BCMA has been transfected into the cells.

[0109] III. Fusions and Conjugates

[0110] The invention provides fusions or conjugates comprising an antibody of the invention. The fusions or conjugates can be produced by fusing or conjugating an antibody of the invention to a heterologous molecule.

[0111] In some embodiments, the polypeptide of the antibody of the present invention can be fused or conjugated with one or more heterologous molecules, where the heterologous molecules include but are not limited to proteins / polypeptides / peptides, markers, drugs and cytotoxic agents.Methods for fusing or conjugating proteins, polypeptides or peptides or chemical molecules with antibodies are known in the art.See, for example, US5,336,603, US5,622,929 and EP367,166.

[0112] In one embodiment, an antibody of the invention is recombinantly fused with a heterologous protein or polypeptide or peptide to form a fusion protein, hi another embodiment, an antibody of the invention binds to a protein or non-protein molecule to form a complex.

[0113] In some embodiments, antibodies of the invention, in the form of full length antibodies or antibody fragments, can be fused or conjugated to heterologous molecules.

[0114] Linkers are used to covalently link different entities in the fusions and / or conjugates of the invention. Linkers include chemical linkers or single peptide linkers. In some embodiments, the antibodies of the invention are fused to other peptide fragments or proteins by peptide linkers. In some embodiments, the antibodies of the invention are linked to other molecules, such as markers or drug molecules, by chemical linkers.

[0115] The peptide linker of the present invention comprises a peptide consisting of amino acid residues. Such linker peptides are usually flexible, and the antigen-binding moieties linked thereto can move independently. The length of the linker peptide can be easily determined by those skilled in the art according to the actual situation, for example, at least 4 to 15 amino acids in length, or longer, for example, about 20 to 25 amino acids in length.

[0116] IV. METHODS AND COMPOSITIONS FOR DIAGNOSIS AND DETECTION

[0117] The invention provides for the use of the anti-BCMA antibodies, fusions or conjugates of the invention in diagnosis and detection. Any of the anti-BCMA antibodies, fusions or conjugates provided herein may be used to detect the presence of human BCMA in a biological sample.

[0118] The term "detection" as used herein includes quantitative or qualitative detection. Exemplary detection methods include, but are not limited to, immunohistochemistry, immunocytochemistry, flow cytometry (e.g., FACS), magnetic beads conjugated with antibody molecules, ELISA assays, PCR-techniques (e.g., RT-PCR). In some embodiments, the biological sample comprises a body fluid, cell, or tissue. In some embodiments, the biological sample is blood, serum, or other liquid sample derived from an organism.

[0119] In one embodiment, a method is provided for the diagnosis or detection of an anti-BCMA antibody, fusion or conjugate. In a further aspect, a method is provided for detecting the presence of BCMA in a biological sample. In some embodiments, the method comprises contacting a biological sample with an anti-BCMA antibody, fusion or conjugate described in the present application under conditions that allow the anti-BCMA antibody, fusion or conjugate to bind to BCMA, and detecting whether a complex is formed between the anti-BCMA antibody, fusion or conjugate and BCMA. Such a method may be an in vitro or in vivo method.

[0120] In one embodiment, the anti-BCMA antibody, fusion or conjugate is used to select subjects suitable for anti-BCMA antibody therapy, for example, where BCMA is the patient's biological marker of choice. Exemplary diseases that can be diagnosed using the antibodies, fusions or conjugates of the invention include B cell-related diseases, e.g., multiple myeloma. In some embodiments, a method is provided for classifying a multiple myeloma (MM) patient with the antibodies, fusions or conjugates of the invention, comprising determining whether the patient's B cells, preferably malignant B cells, express BCMA protein on the surface of the B cells, where if the B cells express BCMA protein on their surface, the patient may be treated accordingly with a therapeutic agent (e.g., an anti-BCMA antibody) that targets BCMA. In some embodiments, the anti-BCMA antibody can be conjugated to a diagnostic or detectable reagent. In some embodiments, the invention provides a reagent kit for diagnosis or detection that includes any of the anti-BCMA antibodies, fusions or conjugates of the invention.

[0121] V. Treatment Methods and Compositions

[0122] The invention provides a method for treating a B cell-related disorder, comprising administering to the subject an effective amount of an antibody or antigen-binding fragment thereof of the invention, or a fusion or conjugate of the invention.

[0123] B cell related disorders are conditions associated with abnormal B cell activity, including, but not limited to, B cell malignancies, plasma cell malignancies, and autoimmune disorders. Exemplary conditions that can be treated using BCMA antibodies include, for example, multiple myeloma, non-Hodgkin's lymphoma, B-cell proliferation of undetermined grade, lymphomatoid granulomatosis, post-transplant lymphoproliferative disorders, immunomodulatory disorders, rheumatoid arthritis, myasthenia gravis, idiopathic thrombocytopenic purpura, antiphospholipid syndrome, Chagas' disease, Graves' disease, Wegener's granulomatosis, polyarteritis nodosa, Sjogren's syndrome, pemphigus vulgaris, scleroderma, multiple sclerosis, ANCA-associated vasculitis, Goodpasture's syndrome, Kawasaki disease, autoimmune hemolytic anemia, and rapidly progressive glomerulonephritis, heavy chain disease, primary or immune cell-associated amyloidosis, or monoclonal gammopathy of undetermined significance, systemic lupus erythematosus, rheumatoid arthritis.

[0124] In some embodiments, the antibodies, fusions and conjugates of the invention are used for the treatment of human B cell related diseases, e.g., B cell malignancies, preferably multiple myeloma (MM) or non-Hodgkin's lymphoma (NHL). In some embodiments, the anti-tumor effects of the anti-BCMA antibodies, fusions and conjugates of the invention include, but are not limited to, for example, a reduction in tumor volume, a reduction in tumor cell number, a reduction in tumor cell proliferation, or a reduction in tumor cell survival.

[0125] It should be understood that the BCMA antibodies, fusions and conjugates of the invention can be administered in combination with other therapeutic modalities to treat the above diseases, e.g., tumors, including therapeutic agents, radiation therapy, chemotherapy, transplantation, immunotherapy, etc. In some embodiments, the antibody molecules, fusions and conjugates of the invention are used in combination with other therapeutic agents. Exemplary therapeutic agents include cytokines, growth factors, steroids, NSAIDs, DMARDs, anti-inflammatory agents, chemotherapeutic agents, radiation therapy agents, therapeutic antibodies, or other active and adjuvant agents, e.g., anti-tumor drugs.

[0126] The following examples are set forth to aid in the understanding of the present invention, and are not intended, nor should they be construed, in any manner, as limiting the scope of the invention as claimed. EXAMPLES

[0127] Example 1 Generation and Expression of Antibodies with Improved BCMA Affinity The heavy and light chain variable region sequences of the BCMA parent antibody ADI-34861 (VH and VL sequences shown in SEQ ID NO: 9 and SEQ ID NO: 18, respectively) and the heavy and light chain variable region sequences of the BCMA parent antibody ADI-34857 (VH and VL sequences shown in SEQ ID NO: 63 and SEQ ID NO: 72, respectively) were obtained from International Application No. PCT / CN2019 / 074419 (BCMA antibody related patent).

[0128] In order to obtain antibodies with improved affinity for BCMA, this example performed affinity mutant design and functional measurements on the BCMA parent antibodies ADI-34861 and ADI-34857.

[0129] The generation of affinity matured Fabs derived from the parent antibodies ADI-34861 and ADI-34857 was carried out by phage display using standard methods (Silacci et al., (2005), Proteomics 5, 2340-50). After several rounds of panning of the parent antibody ADI-34861, the affinity matured antibodies ADI-38491 (having the VH shown in SEQ ID NO: 27, the VL sequence shown in SEQ ID NO: 36) and the antibody ADI-38497 (having the VH shown in SEQ ID NO: 45, the VL sequence shown in SEQ ID NO: 54) were first obtained, and after several rounds of panning of the parent antibody ADI-34857, the affinity matured antibodies ADI-38481 (having the VH shown in SEQ ID NO: 81, the VL sequence shown in SEQ ID NO: 90) and the antibody ADI-38484 (having the VH shown in SEQ ID NO: 99, the VL sequence shown in SEQ ID NO: 108) were first obtained.

[0130] The nucleotide sequence encoding the heavy chain variable region (SEQ ID NO: 26) and the light chain variable region (SEQ ID NO: 35) of antibody ADI-38491, the nucleotide sequence encoding the heavy chain variable region (SEQ ID NO: 44) and the light chain variable region (SEQ ID NO: 53) of antibody ADI-38497, the nucleotide sequence encoding the heavy chain variable region (SEQ ID NO: 80) and the light chain variable region (SEQ ID NO: 89) of antibody ADI-38481, and the nucleotide sequence encoding the heavy chain variable region (SEQ ID NO: 98) and the light chain variable region (SEQ ID NO: 107) of antibody ADI-38484 were constructed in a modified eukaryotic expression vector plasmid pcDNA3.3 (Invitrogen) containing light and heavy chain constant region fragments, respectively, and expressed in the ExpiCHO transient expression system (Thermo Biosciences) according to the manufacturer's instructions. The full-length heavy and light chains of the antibodies were co-expressed in CHO-K cells using ELISA kit (Fisher, A29133) and then purified by Protein A affinity chromatography to obtain antibodies ADI-38491, ADI-38497, ADI-38481 and ADI-38484.

[0131] Example 2 Antibody affinity detection by Fortebio

[0132] The antibody affinity was measured by the capture method of the antibody Fc segment using the capture antibody (AHC) bioprobe of the anti-human antibody Fc segment using the Octet QKe system of Fortebio Co., Ltd. The specific procedure is as follows.

[0133] Antibody ADI-34861, antibody ADI-38491, antibody ADI-38497, antibody ADI-34857, antibody ADI-38481 and antibody ADI-38484 were each diluted to 4 μg / mL in PBS buffer and flowed over the surface of an AHC probe (Cat: 18-0015, PALL) for 120 s. Human, cynomolgus monkey and mouse BCMA (60 nM) were used as the flow phase, with an association time of 180 s and a dissociation time of 180 s. After the experiment was completed, the blank control (PBS buffer) response value was excluded, and the 1:1 Langmuir binding mode fitting was performed using the software to calculate the rate constant of antigen-antibody binding. The rate constants are shown in Table 1 below.

[0134] The results showed that the affinity of the mutated antibodies ADI-38491 and ADI-38497 was significantly improved compared to the corresponding parent antibody ADI-34861, and the affinity of the mutated antibodies ADI-38481 and ADI-38484 was significantly improved compared to the corresponding parent antibody ADI-34857. [Table 1]

[0135] Example 3 Cell-Based Antibody Function Measurements To test the binding affinity of the antibody to BCMA expressed on the cell surface, three types of cells (NCI-H929 cells, BCMA-KO-H929 cells, and human BCMA CHO-S cells) were used for the measurement. NCI-H929 cells (also abbreviated as H929 cells in the specification) (purchased from Nanjing Kebai Biotechnology Co., Ltd.) are human multiple myeloma cell lines that naturally express BCMA molecules on the cell surface, BCMA-KO-H929 cells are cell lines (construction entrusted to Nanjing Jinsirui Biotechnology Co., Ltd.) that are based on H929 cells and specifically target the BCMA gene to induce frameshift mutations using CRISPR-Cas9 technology, and are further unable to normally express BCMA molecules, and human BCMA CHO-S cells were prepared by introducing exogenous human BCMA into CHO-S cells. Method for preparing human BCMA CHO-S cells: A sequence encoding human BCMA (NP_001183.2, SEQ ID NO: 109) was cloned into the polyclonal site of the pcDNA3.3 (Invitrogen) vector to obtain an expression vector expressing human BCMA. The expression vector expressing human BCMA was then introduced into CHO-S cells (ATCC) to perform eukaryotic expression, thereby obtaining CHO-S cells expressing human BCMA on the cell surface.

[0136] Human BCMA CHO-S cells or H929 cells were cultured at 1.0 × 10 5Cells / well were seeded into a 96-well plate and diluted 10 nM of each antibody (antibody ADI-34861, antibody ADI-38491, antibody ADI-38497, antibody ADI-34857, antibody ADI-38481 and antibody ADI-38484) was added. After incubation at 4°C for 30 minutes, the cells were washed and 100 μL of APC-labeled goat anti-human IgG secondary antibody (Jackson ImmunoResearch Inc, Cat. No.: 109-136-097, Allophycocyanin (APC) AffiniPure F(ab')2 Fragment Goat Anti-Human IgG, F(ab')2fragment specific) was added and incubated at 4°C for 30 minutes. The cells were then washed and the binding of each antibody to BCMA molecules expressed on the cell surface was detected by flow cytometry (Beckman Coulter). CHO-S cells were used as a negative control. [Table 2]

[0137] As can be seen from Table 2, antibodies ADI-34861, ADI-38491, and ADI-38497 all bound to BCMA expressed on the cell surface, and the binding affinity of antibody ADI-38497 to BCMA expressed on the cell surface was significantly improved. Antibodies ADI-34857, ADI-38481, and ADI-38484 all bound to BCMA expressed on the cell surface, and the binding affinity of antibodies ADI-38481 and ADI-38484 to BCMA expressed on the cell surface was significantly improved.

[0138] In addition, H929 cells and BCMA-KO-H929 cells were cultured at 3.0 × 10 5Cells / well were seeded into a 96-well plate and diluted ADI-38497 antibody (1 μg / well) was added, with no antibody added to negative control wells. After 30 min incubation at 4° C., cells were washed and 100 μL of APC-labeled goat anti-human IgG secondary antibody (Jackson ImmunoResearch Inc, Catalog No.: 109-136-097) was added to all cell wells and incubated for 30 min at 4° C. Cells were then washed and the binding of antibody ADI-38497 antibody to BCMA molecules expressed on the surface of each cell was detected by flow cytometry.

[0139] As can be seen from Figure 1, the ADI-38497 antibody binds only to H929 cells expressing the BCMA antigen, but does not bind to BCMA-KO-H929 cells in which the BCMA gene has been knocked out, indicating that the ADI-38497 antibody can specifically bind to the BCMA antigen.

[0140] Example 4 Preparation of ADI-38497WT antibody, ADI-38497PG antibody, ADI-38484WT antibody, and ADI-38484 PG antibody, and detection of antigen-binding activity

[0141] 4.1 Preparation of ADI-38497WT, ADI-38497PG, ADI-38484WT and ADI-38484PG Antibodies

[0142] From the US9273141B2 patent, the light chain variable region sequence and the heavy chain variable region sequence of the BCMA antibody clone J6M0 from GSK were obtained as a control antibody (GSK IgG).

[0143] The light chain variable region sequences and heavy chain variable region sequences of GSK IgG, ADI-38497, and ADI-38484 antibodies were used to load the human-derived IgG1 heavy chain constant region containing WT (SEQ ID NO: 110) or the human-derived IgG1 heavy chain constant region containing P329G point mutation (SEQ ID NO: 111) and κ light chain constant region (SEQ ID NO: 112) into pcDNA3.4 expression vectors (purchased from Shanghai Boxing). The light and heavy chain expression vectors were co-transfected into HEK293 cells with PEI at a molar ratio of 2:3, and the medium supernatant was collected after culturing for 5 to 7 days. The supernatant medium containing the antibody was further purified by Protein A column and then dialyzed with PBS. The concentration was detected by reading the absorbance value at 280 nm on a NanoDrop instrument, and the purity of the sample was detected using SDS-PAGE and SEC-HPLC methods. GSK WT antibody, GSK PG antibody, ADI-38497WT antibody, ADI-38497PG antibody, ADI-38484WT antibody, and ADI-38484PG antibody were obtained.

[0144] 4.2 Affinity detection of ADI-38497PG antibody

[0145] The affinity of the ADI-38497PG antibody to different species of BCMA was measured by Biacore T200, and Figure 2A shows a schematic diagram of the method for measuring antibody affinity using surface plasmon resonance (SPR).

[0146] The specific method is as follows: anti-human Fc IgG (Ab97221, Abcam) was coupled to the surface of a CM5 chip (29149603, Cytiva), and then the ADI-38497PG antibody was captured on the chip surface, and the affinity and rate constants were obtained by detecting the binding and dissociation between the antibody on the chip surface and the BCMA antigen in the flow phase. In the measurement process, 10-fold diluted 10×HBS-EP+ (BR-1006-69, Cytiva) was used as the experimental buffer. Each cycle in affinity detection includes the capture of the ADI-38497PG antibody, binding to one concentration of antigen, and chip regeneration. The antigen after gradient dilution (antigen is a concentration gradient of 1.25 nM to 40 nM, diluted 2-fold) was flowed over the chip surface in order from low concentration to high concentration at a flow rate of 30 μL / min, and the binding time was set to 180 s, and the appropriate dissociation time (900 s, 600 s, or 60 s) was set. Finally, the chip was regenerated with 10 mM glycine-HCl, pH 1.5 (BR-1003-54, Cytiva).

[0147] Data results were analyzed using the Biacore T200 analysis software (version 3.1) using a 1:1 binding model.

[0148] Figure 2B shows the representative affinity SPR measurement spectra of ADI-38497PG antibody for recombinant human, cynomolgus monkey, mouse, rat and rabbit BCMA proteins. The results showed that ADI-38497PG antibody could bind to any of the BCMA proteins from different species, with the order of binding activity being human BCMA>monkey BCMA>mouse BCMA>rat BCMA>rabbit BCMA. [Table 3]

[0149] 4.3 Detection of binding activity of P329G BCMA antibody to BCMA antigens from different species

[0150] First, we prepared CHO GS cells expressing BCMA antigens from different species. Specifically, we synthesized BCMA genes from human, mouse, and cynomolgus monkeys, cloned them into lentivirus vectors, packaged lentiviruses containing BCMA genes from different species, infected CHO GS cells with the lentiviruses, and then selected them by flow cytometry to obtain CHO GS cell lines expressing BCMA antigens from different species, namely hBCMA-CHO GS, mBCMA-CHO GS, and cynoBCMA-CHO GS cells.

[0151] Next, ADI-38497PG antibody and BCMA antibody from GSK (i.e., GSK PG IgG was used as the Benchmark) were prepared in FACS buffer to different concentrations of antibody solutions by 10-fold gradient dilution, and incubated with 1E5 CHO GS cells expressing the prepared BCMA antigens from different species at 4°C for 30 minutes, respectively, washed with FACS buffer, and further incubated with APC-goat anti-human IgG specific for Fcγ fragment (Jackson ImmunoResearch, 109-136-098) for 30 minutes at 4°C. The P329G antibody bound to the cells was detected by flow cytometry, and the APC channel MFI was analyzed, and the antibody concentration was plotted on the X-axis and the APC channel MFI on the Y-axis, and the EC50 of binding was calculated.

[0152] Figure 2C shows the binding ability of different concentrations of P329G BCMA antibody to CHO-GS cells stably expressing human, cynomolgus monkey and mouse BCMA. As can be seen from Figure 2C, ADI-38497PG IgG antibody can bind to different species of BCMA expressed on the cell surface, but the BCMA antibody from GSK (Benchmark) has relatively high species BCMA specificity and does not recognize mouse BCMA, which is consistent with the SPR detection results. [Table 4]

[0153] 4.4 Detection of binding activity of P329G BCMA antibody to tumor cell surface BCMA antigen

[0154] An appropriate amount of tumor cells in the logarithmic growth phase was taken, washed twice with FACS buffer, and added with ADI-38497PG antibody, ADI-38484PG antibody, and GSK PG IgG used as a benchmark. Isotype hIgG1 antibody was added to the staining control cells, stained for 30 minutes at 4°C, washed twice, and APC-F(ab')2 fragment goat anti-human IgG antibody was added, stained for 30 minutes at 4°C. The cells were washed twice, resuspended in FACS buffer, and detected using a flow cytometer.

[0155] Figure 2D shows the effect of different concentrations of P329G BCMA antibody on the BCMA-expressing positive multiple myeloma cell lines MM.1s, RPMI8226, U266, H929, L363 and AMO1 (MM.1s (CBP60239) was purchased from Nanjing Kebai Biotechnology Co., Ltd., RPMI8226 (CBP60244) was purchased from Nanjing Kebai Biotechnology Co., Ltd., U266 (CL-0510) was purchased from Wuhan Putunos Biotechnology Co., Ltd., and H 929 (CBP60243) purchased from Nanjing Kebai Biotechnology Co., Ltd., L363 (CBP6024) purchased from Nanjing Kebai Biotechnology Co., Ltd., and AMO1 (CBP60242) purchased from Nanjing Kebai Biotechnology Co., Ltd.), and ADI-38497PG antibody and ADI-38484PG antibody showed binding activity to BCMA-expressing positive tumor cells and showed concentration-dependence. Among the positive tumor cells expressing BCMA, MM.1s cells expressed BCMA at the highest level, RPMI8226, U266 and H929 cells expressed BCMA at moderate levels, and L363 and AMO1 cells expressed BCMA at low levels. [Table 5]

[0156] Example 5 Detection of the biological functions of ADI-38497WT and ADI-38497PG antibodies

[0157] 5.1 Detection of ADCC effector function

[0158] PBMC cells (Peripheral Blood Mononuclear Cells) of donor 3 were resuscitated, resuspended in RPMI1640 medium containing 10% fetal bovine serum, and stabilized at 37°C for 1-2 hours. PBMCs were mixed with target cells at a potency-target ratio of 25:1, mixed with different concentrations of BCMA antibodies, and continued to be cultured at 37°C for 4 and 24 hours, respectively, and the antibody-mediated killing effect of PBMCs on target cells was detected using an LDH detection kit (Promega, G1780), with antibody concentration on the X-axis and cell lysis ratio on the Y-axis plotted and analyzed. Cells were simultaneously collected, washed twice with FACS buffer, and CD3, CD56, CD16 and CD107a antibodies were added, where CD107a antibody needs to be added in advance and co-incubated with cells at 37°C for 1 hour. The above cell-antibody mixture was stained for 30 min at 4° C., washed twice, resuspended in FACS buffer, and detected using a flow cytometer.

[0159] FIG. 3A shows the ability of ADI-38497WT and ADI-38497PG antibodies to mediate ADCC killing, and the results showed that only the WT antibody mediated ADCC cytotoxic killing effect against BCMA-expressing positive H929 tumor cells, while the P329G mutant antibody lacked the ability to induce ADCC effect, both when different incubation times (4 h, 24 h) were tested and different detection indicators were used (cytotoxicity against target cells, effect on CD3, CD56, CD16 and CD107a expression).

[0160] 5.2 Detection of ADCP effect function

[0161] ADCP reporter cell line (Promega, G9871) and H929 cells in logarithmic growth phase were taken, and ADCP reporter cells were mixed with H929 target cells at a potency-target ratio of 2:1 and 5:1, and mixed with different concentrations of BCMA antibodies, and continued to be cultured at 37°C for 20 hours. The antibody-mediated target cell-dependent reporter cell activation effect was detected using a luciferase detection kit (Promega, E2620), and the antibody concentration was plotted on the X-axis and the change in fluorescence readings on the Y-axis for analysis.

[0162] Figure 3B showed the ability of ADI-38497WT and ADI-38497PG antibodies to mediate ADCP killing. The results showed that only ADI-38497WT antibody mediated ADCP killing effect on BCMA-expressing positive H929 tumor cells when different potency-target ratios (2:1 or 5:1) were tested, while P329G mutant antibody lacked the ability to induce ADCP killing effect.

[0163] 5.3 Detection of anti-proliferative function of P329G mutant antibody

[0164] Logarithmic growth phase H929 cells and L363 cells were taken and seeded into well plates according to a certain number, and a portion of logarithmic growth phase H929 cells and L363 cells were treated with mitomycin C as target cells and used as positive control. Then, different concentrations of ADI-38497PG antibody were added and mixed, and continued to be cultured at 37°C for 48 hours, 72 hours and 120 hours, respectively, and CellTiter-Glo (Promega, G9242) was used to detect the live cell ratio, and the co-incubation time was plotted on the X-axis and the fluorescence reading value was plotted on the Y-axis for analysis.

[0165] FIG. 3C shows whether the ADI-38497PG antibody has the ability to inhibit tumor cell proliferation, and the results showed that the ADI-38497PG antibody itself lacked inhibitory ability against tumor cell proliferation, both when different incubation times (48 hours, 72 hours, and 120 hours) and different ADI-38497PG antibody concentrations (5 μg / mL, 50 μg / mL) were tested.

[0166] Example 6 In vivo pharmacokinetic study of ADI-38497PG antibody

[0167] 6.1 Antibody injection and sampling

[0168] BALB / c mice (4 weeks to 6 weeks old, weighing 15g to 17g, female) were divided into three groups, each with 9 mice: an ADI-38497PG antibody 1mg / kg group, an ADI-38497PG antibody 10mg / kg group, and an ADI-38497PG antibody 200mg / kg group. The antibodies were diluted to 0.1mg / mL, 1mg / mL, and 20mg / mL with 1xPBS so that the administration volume for each mouse was 10mL / kg, i.e., the antibody doses were 1mg / kg, 10mg / mL, and 200mg / mL, respectively, the administration method was intravenous injection, and the administration frequency was a single dose. 100 μL of blood samples were collected from the retroorbital plexus of the mice 5 min, 30 min, 2 h, 6 h, 24 h, 48 h, 96 h, 168 h, 336 h, and 504 h after antibody administration, centrifuged at 3000 g, and the supernatant was aspirated and used to measure blood drug concentrations.

[0169] 6.2 Detection of ADI-38497PG antibodies A 96-well microplate was coated the day before. BCMA antigen was diluted to 1 μg / mL with coating solution (1 pack of carbonate (Thermo, 28382) powder was taken, dissolved in 400 mL of ultrapure water, adjusted to 500 mL, and mixed uniformly to form coating solution), 100 μL / well, sealed with sealing film, and left at room temperature overnight. After discarding the coating solution and tapping dry on absorbent paper, 300 μL of washing solution was added to each well, shaken for 10 seconds to mix uniformly, tapped dry the washing solution, and then washed three times. Blocking solution was added with a pipette at 200 μL / well, sealed with sealing film, and incubated at room temperature for 2 h. The plate was then washed once. The diluted standard curve (a gradient dilution was made with a BCMA antibody of known concentration to create a standard curve (for example, a standard curve was created with an ADI-38497PG antibody of known concentration)), quality control samples, and samples waiting to be measured were incubated at room temperature for 2 h at 100 μL / well. After discarding the pre-coating solution and tapping dry on absorbent paper, 300 μL of washing solution was added to each well, shaken for 10 seconds to mix evenly, tapped dry the washing solution, and then repeated washing three times. Once. Goat anti-human IgG-Fc-HRP antibody (BETHYL) was diluted 1:100000, 100 μL was added to each well, and incubated at room temperature in the dark for 1 h. The plate was then washed once. TMB substrate was added to the 96-well microplate at 100 μL / well and allowed to develop for 5 minutes at room temperature in the dark. 50 μL of ELISA stop solution was added to each well, shaken for 10 seconds, and OD450nm and OD620nm values ​​were read within 30 minutes.

[0170] 4A and 4B show the pharmacokinetic experiment results of ADI-38497PG antibody (also abbreviated as PG Ab in the following mouse in vivo experiment) in mice. After 1 mg / kg, 10 mg / kg, and 200 mg / kg of ADI-38497PG antibody were intravenously injected into mice, the exposure amount (Cmax and AUClast) of ADI-38497PG antibody in serum showed a dose-dependent effect, and there was no significant difference in other pharmacokinetic parameters. As shown in Table 6, ADI-38497PG antibody 1 mg / kg: AUC0-inf, Cmax, CL, and T1 / 2 were 2480 μg×h / mL, 30 μg / mL, 0.40 mL / kg / h, and 145 h, respectively, and ADI-38497PG antibody 10 mg / kg: AUC0-inf, Cmax, CL, and T1 / 2 were 2480 μg×h / mL, 30 μg / mL, 0.40 mL / kg / h, and 145 h, respectively. ADI-38497PG antibody 200mg / kg: AUC0-inf, Cmax, CL, T1 / 2 were 24720μg×h / mL, 187μg / mL, 0.32mL / kg / h, 219h, respectively, and ADI-38497PG antibody 200mg / kg: AUC0-inf, Cmax, CL, T1 / 2 were 397734μg×h / mL, 3895μg / mL, 0.43mL / kg / h, 197h, respectively, indicating that the half-life of ADI-38497PG antibody 1mg / kg is slightly shorter than that of ADI-38497PG antibody 10mg / kg and 200mg / kg. [Table 6]

[0171] Example 7 In vivo antitumor effect of ADI-38497PG antibody

[0172] Mouse tumor inoculation and treatment were performed by resuspending H929 cells in 1× PBS and then incubating at 5×10 6 A cell suspension with a cell concentration of 1 × 10 cells / mL was prepared. The right back of NOG mice (4-6 weeks old, body weight 15-17 g, female) was shaved, and an injection volume of 0.2 mL / mouse, i.e., an inoculum amount of 1 × 10 cells / mL, was prepared. 6 H929 cell suspension was injected subcutaneously at 1000 cells / mouse. Seven days after tumor cell inoculation, the mouse tumor volume was 50.82 mm 3 ~104.36mm 3The mice were divided into a PBS carrier group and an ADI-38497PG antibody group (also referred to as the "PG Ab group" in the specification), with 7 mice in each group. After grouping, the antibody was administered to each mouse on the 7th day, with a volume of 10 mL / kg, a frequency of administration once a week, and an administration method of intraperitoneal injection. The mouse body weight, the maximum long axis (L) and the maximum wide axis (W) of the tumor tissue were monitored twice a week.

[0173] Figure 5A shows the therapeutic effect of ADI-38497PG antibody in immunodeficient tumor-bearing mice subcutaneously inoculated with human BCMA expression-positive H929 tumor cells. The results showed that administration of PG antibody in the BCMA-highly expressing H929 tumor model produced a remarkable antitumor effect.

[0174] Figure 5B shows the changes in mouse body weight in the experiment. The results showed that there was no significant change in mouse body weight after administration of PG antibody in the H929 tumor model with high BCMA expression.

[0175] Therefore, the ADI-38497PG antibody has a significant anti-BCMA high-expressing tumor effect without any apparent toxicity or side effects.

[0176] Example 8 Study of the in vivo anti-systemic tumor effect of ADI-38497PG antibody

[0177] First, H929-luc cells were prepared. Specifically, H929 cells (purchased from Nanjing Kebai Biotechnology Co., Ltd.) were used to package lentiviruses containing GFP-luciferase genes, and the resulting lentiviruses were infected into H929 cells, which were then sorted by flow cytometry to obtain a GFP and luciferase dual-expressing H929-luc cell line.

[0178] Next, resuspend the H929-luc cells in 1x PBS and dilute them to 25 x 10 6A cell suspension was prepared with a cell concentration of 1.17 × 10 cells / mL. The H929-luc cell suspension was injected into NOG mice (4-6 weeks old, body weight 15-17 g, female) via the tail vein at an injection volume of 0.2 mL / mouse. 14 days after tumor cell inoculation, the substrate D-Luciferin (15 mg / mL) was injected intraperitoneally at an injection volume of 10 mL / kg / mouse, and IVIS spectrum imaging analysis was performed 10 minutes after substrate injection. The fluorescent signal was 1.17 × 10 7 photons / sec~1.43×10 8 The mice were divided into a carrier group, a PG Ab, 0.3mg / kg group, and a PG Ab, 3mg / kg group, with 6 to 7 mice in each group. Antibodies were prepared at concentrations of 0.03mg / mL and 0.3mg / mL, respectively, and from the 14th day after grouping, the antibodies were administered to each mouse at a volume of 10mL / kg, a frequency of administration once a week, and an administration method of intraperitoneal injection.

[0179] Figure 6A shows the antitumor efficacy of different doses of PG antibody in immunodeficient tumor-bearing mice inoculated with human H929-luc tumor cells via the tail vein. The results showed that in the systemic tumor model, PG antibody began to produce antitumor efficacy about one week after administration, and showed dose-dependency, and the efficacy was maintained for two weeks and then gradually decreased.

[0180] Figure 6B shows the changes in mouse body weight in the above experiment. The results showed that the mouse body weight in each treatment group increased moderately during treatment, suggesting that treatment with PG antibody did not induce obvious toxicity.

[0181] Example 9 In vivo toxicological study of ADI-38497PG antibody

[0182] Mouse tumor inoculation and treatment were performed by resuspending H929 cells in 1× PBS and then incubating at 5×10 6 A cell suspension with a cell concentration of 5 × 10 cells / mL was prepared. The right back of a NOG mouse (4-6 weeks old, body weight 15-17 g, female) was shaved and incubated for 1 h. 6The H929 cell suspension was subcutaneously injected at 100x100 / mL with an injection volume of 0.2 mL / mouse. Six days after tumor cell inoculation, the mouse tumor volume was 38.49 mm 3 ~104.77mm 3 The mice were divided into a non-tumor-bearing carrier group, a tumor-bearing carrier group, and a PG Ab group, with 24 mice in each group, as shown in Table 7. Antibodies at a concentration of 1 mg / mL were prepared, and after grouping was completed, the antibodies were administered to each mouse so that the administration volume was 10 mL / kg, the administration frequency was once a week, the number of administrations was three times, and the administration method was intraperitoneal injection. The mouse body weight, the maximum long axis (L) and the maximum wide axis (W) of the tumor tissue were monitored twice a week. For hematological and blood biochemical detection, peripheral blood was collected from four mice in each group before the first antibody administration, before the third antibody administration, and at the end of the experiment. [Table 7] Figure 7A shows the therapeutic effect of PG antibody in immunodeficient tumor-bearing mice subcutaneously inoculated with human H929 tumor cells. The results showed that PG antibody had antitumor effect.

[0183] Figure 7B shows the body weight change of the mice in this experiment. The results showed that the body weight did not change obviously during the treatment with PG antibody compared with the control mice, suggesting that the PG antibody did not induce obvious toxic reactions.

[0184] Figure 7C and Figure 7D show the hematological and blood biochemical detection results of the mice in the above experiment. The results showed that the hematological and blood biochemical indicators of the mice during PG antibody treatment did not change obviously compared with the control mice, suggesting that the PG antibody treatment had no toxic reaction.

[0185] Although exemplary embodiments of the present invention have been described above, those skilled in the art should understand that these disclosures are merely exemplary and that various other substitutions, adaptations and modifications can be made within the scope of the present invention. Accordingly, the present invention is not limited to the specific embodiments set forth herein.

[0186]

Table 8-1

Table 8-2

Table 8-3

Table 8-4

Table 8-5

Table 8-6

Table 8-7

Table 8-8

Table 8-9

Table 8-10

Table 8-11

Claims

1. An antibody or antigen-binding fragment thereof that specifically binds to BCMA, comprising a heavy chain variable region and a light chain variable region, (a) The heavy chain variable region is numbered according to Kabat numbering as follows: HCDR1 represented by GSIVSSSYYWT (SEQ ID NO: 37); HCDR2 represented by SISIAGSTYYNPSLKS (SEQ ID NO: 38); HCDR3 represented by ARDRGDQILDV (SEQ ID NO: 39); The light chain variable region is numbered according to Kabat numbering as follows: LCDR1 represented by RASQSISRYLN (SEQ ID NO: 46); LCDR2 represented by AASSLQS (SEQ ID NO: 47); LCDR3 represented by QQKYFDIT (SEQ ID NO: 48); (b) The heavy chain variable region comprises an HCDR1 represented by the following sequence according to Kabat numbering: GSIVSSSYYWT (SEQ ID NO: 19); an HCDR2 represented by the following sequence: SISIAGSTYYNPSLKS (SEQ ID NO: 20); and an HCDR3 represented by the following sequence: ARDRGDTILDV (SEQ ID NO: 21). the light chain variable region comprises an LCDR1 represented by RASQSISRYLN (SEQ ID NO: 28); an LCDR2 represented by AASSLQS (SEQ ID NO: 29); and an LCDR3 represented by QQKYFDIT (SEQ ID NO: 30), according to Kabat numbering; (c) The heavy chain variable region comprises an HCDR1 set forth in Kabat numbering as follows: GTFSNDVIS (SEQ ID NO: 73); an HCDR2 set forth in Kabat numbering as follows: VIIPIFGIANYAQKFQG (SEQ ID NO: 74); and an HCDR3 set forth in Kabat numbering as follows: ARGRGYYSSWLLDI (SEQ ID NO: 75). the light chain variable region comprises an LCDR1 set forth in Kabat numbering as follows: QASQDITNYLN (SEQ ID NO: 82); an LCDR2 set forth in DASNLET (SEQ ID NO: 83); and an LCDR3 set forth in QQAFDLIT (SEQ ID NO: 84); or (d) The heavy chain variable region comprises an HCDR1 set forth in Kabat numbering as follows: GTFSNDVIS (SEQ ID NO: 91); an HCDR2 set forth in Kabat numbering as follows: VIIPIFGIANYAQKFQG (SEQ ID NO: 92); and an HCDR3 set forth in Kabat numbering as follows: ARGRGYYSSWLHDI (SEQ ID NO: 93). The light chain variable region comprises an LCDR1 represented by QASQDITNYLN (SEQ ID NO: 100), an LCDR2 represented by DASNLET (SEQ ID NO: 101), and an LCDR3 represented by QQAFDLIT (SEQ ID NO: 102), according to Kabat numbering. An antibody or antigen-binding fragment thereof that specifically binds to BCMA.

2. An antibody or antigen-binding fragment thereof that specifically binds to BCMA, (a) three CDRs in the amino acid sequence of a heavy chain variable region set forth in SEQ ID NO: 45 and three CDRs in the amino acid sequence of a light chain variable region set forth in SEQ ID NO: 54; (b) three CDRs in the amino acid sequence of a heavy chain variable region set forth in SEQ ID NO: 27 and three CDRs in the amino acid sequence of a light chain variable region set forth in SEQ ID NO: 36; (c) three CDRs in the amino acid sequence of a heavy chain variable region set forth in SEQ ID NO: 81 and three CDRs in the amino acid sequence of a light chain variable region set forth in SEQ ID NO: 90; or (d) three CDRs in the amino acid sequence of a heavy chain variable region set forth in SEQ ID NO: 99 and three CDRs in the amino acid sequence of a light chain variable region set forth in SEQ ID NO: 108; Including, An antibody or antigen-binding fragment thereof that specifically binds to BCMA.

3. 2. The antibody or antigen-binding fragment thereof that specifically binds to BCMA according to claim 1, comprising a heavy chain variable region and a light chain variable region, (a) the heavy chain variable region comprises the sequence of SEQ ID NO:45, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity thereto, and the light chain variable region comprises the sequence of SEQ ID NO:54, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto; (b) the heavy chain variable region comprises the sequence of SEQ ID NO: 27, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity thereto, and the light chain variable region comprises the sequence of SEQ ID NO: 36, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity thereto; (c) the heavy chain variable region comprises the sequence of SEQ ID NO: 81, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity thereto, and the light chain variable region comprises the sequence of SEQ ID NO: 90, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity thereto; or (d) the heavy chain variable region comprises the sequence of SEQ ID NO: 99, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereof, and the light chain variable region comprises the sequence of SEQ ID NO: 108, or a sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereof; An antibody or antigen-binding fragment thereof that specifically binds to BCMA.

4. 4. The antibody or antigen-binding fragment thereof that specifically binds to BCMA according to claim 3, comprising a heavy chain variable region and a light chain variable region, The antibody or antigen-binding fragment thereof (a) a heavy chain variable region set forth in SEQ ID NO: 45 and a light chain variable region set forth in SEQ ID NO: 54; (b) a heavy chain variable region set forth in SEQ ID NO: 27 and a light chain variable region set forth in SEQ ID NO: 36; (c) a heavy chain variable region set forth in SEQ ID NO: 81 and a light chain variable region set forth in SEQ ID NO: 90; or (d) a heavy chain variable region set forth in SEQ ID NO: 99 and a light chain variable region set forth in SEQ ID NO: 108; An antibody or antigen-binding fragment thereof that specifically binds to BCMA.

5. an IgG1, IgG2, IgG3 or IgG4 antibody, optionally an IgG1 or IgG4 antibody, optionally an IgG1 antibody; Optionally, the antigen-binding fragment is a Fab, Fab', F(ab')2, Fv, single-chain Fv, single-chain Fab, or diabody. An antibody or antigen-binding fragment thereof that specifically binds to BCMA according to claim 1.

6. 2. The antibody or antigen-binding fragment thereof that specifically binds to BCMA of claim 1, further comprising a mutated Fc domain: wherein the amino acid at position P329 according to EU numbering is mutated to glycine (G), and Fcγ receptor binding of the variant Fc domain is reduced compared to Fcγ receptor binding of the non-mutated parent antibody Fc domain; optionally, said variant Fc domain is a variant Fc domain of an IgG1, IgG2, IgG3, or IgG4 antibody; optionally, said variant Fc domain is a variant Fc domain of an IgG1 or IgG4 antibody; optionally, said variant Fc domain is a variant Fc domain of an IgG1 antibody; Optionally, the antibody or antigen-binding fragment thereof comprises a heavy chain constant region sequence set forth in SEQ ID NO: 111, or a sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity thereto and an amino acid at position P329 according to EU numbering mutated with G; Optionally, the antibody or antigen-binding fragment thereof comprises a heavy chain constant region sequence set forth in SEQ ID NO: 111, or a sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical thereto and having the amino acid at position P329 according to EU numbering mutated with a G; and a light chain constant region sequence set forth in SEQ ID NO: 112, or a sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical thereto; Optionally, the antibody or antigen-binding fragment thereof comprises a heavy chain constant region sequence set forth in SEQ ID NO:111 and a light chain constant region sequence set forth in SEQ ID NO:112; An antibody or antigen-binding fragment thereof that specifically binds to BCMA.

7. The antibody or antigen-binding fragment thereof that specifically binds to BCMA according to claim 1, The following characteristics: (1) the property of binding to BCMA, such as human BCMA, cynomolgus monkey BCMA, and mouse BCMA, with high affinity, optionally with a binding K between the anti-BCMA antibody or antigen-binding fragment thereof and BCMA, as measured by a ForteBio kinetic binding assay; Ｄ is about 10 －９ M ~ about 10 －１２ M, (2) the property of specifically binding to BCMA expressed on the cell surface; (3) the property of having an ADCC cytotoxic killing effect on BCMA-expressing cells; (4) The property of having an ADCP killing effect on cells expressing BCMA; (5) The ability to inhibit and suppress the growth of and / or kill cells expressing human BCMA (particularly multiple myeloma cells); and (6) The property of having an in vivo antitumor effect against BCMA-expressing tumors without any obvious toxicity or side effects; having one or more of An antibody or antigen-binding fragment thereof that specifically binds to BCMA.

8. An isolated nucleic acid encoding the anti-BCMA antibody or antigen-binding fragment thereof of any one of claims 1 to 7.

9. A vector comprising the nucleic acid of claim 8, optionally an expression vector.

10. 9. A host cell comprising the nucleic acid of claim 8 or a vector comprising said nucleic acid, optionally the host cell is a prokaryotic or eukaryotic cell, optionally selected from an E. coli cell, a yeast cell, a mammalian cell, or other cell suitable for preparing the antibody or antigen-binding fragment thereof, and optionally a HEK293 cell or a CHO cell.

11. 11. A method for preparing the anti-BCMA antibody or antigen-binding fragment thereof of any one of claims 1 to 7, comprising culturing the host cell of claim 10 under conditions suitable for expression of a nucleic acid encoding the anti-BCMA antibody or antigen-binding fragment thereof of any one of claims 1 to 7, optionally isolating the anti-BCMA antibody or antigen-binding fragment thereof, and optionally further comprising recovering the anti-BCMA antibody or antigen-binding fragment thereof from the host cell.

12. A conjugate, fusion or bispecific antibody comprising the anti-BCMA antibody or antigen-binding fragment thereof of any one of claims 1 to 7.

13. A pharmaceutical composition comprising an anti-BCMA antibody or antigen-binding fragment thereof according to any one of claims 1 to 7, or a conjugate, fusion or bispecific antibody comprising the anti-BCMA antibody or antigen-binding fragment thereof according to any one of claims 1 to 7, and optionally a pharmaceutically acceptable carrier.

14. 14. The pharmaceutical composition of claim 13 for preventing or treating a B-cell related disease in a subject, comprising: Optionally, the B cell related disease is selected from the group consisting of B cell malignancies, plasma cell malignancies, and autoimmune diseases, and optionally includes multiple myeloma, non-Hodgkin's lymphoma, B cell proliferation of undetermined grade, lymphomatoid granulomatosis, post-transplant lymphoproliferative disorders, immunoregulatory disorders, rheumatoid arthritis, myasthenia gravis, idiopathic thrombocytopenic purpura, antiphospholipid syndrome, Chagas' disease, Graves' disease, Wegener's granulomatosis, polyarteritis nodosa, Sjogren's syndrome, psoriasis vulgaris, and the like. The pharmaceutical composition is selected from the group consisting of smallpox, scleroderma, multiple sclerosis, ANCA-associated vasculitis, Goodpasture's syndrome, Kawasaki disease, autoimmune hemolytic anemia, and rapidly progressive glomerulonephritis, heavy chain disease, primary or immune cell-associated amyloidosis, or monoclonal gammopathy of undetermined significance, and optionally, the B-cell related disease is a B-cell malignancy, and optionally, multiple myeloma (MM) or non-Hodgkin's lymphoma (NHL).

15. 10. A kit for detecting BCMA in a sample, the kit comprising the anti-BCMA antibody or antigen-binding fragment thereof of any one of claims 1 to 7, and the kit comprising the following steps: (a) contacting a sample with the anti-BCMA antibody or antigen-binding fragment thereof of any one of claims 1 to 7; and (b) detecting the formation of a complex between the anti-BCMA antibody or antigen-binding fragment thereof and BCMA; is used to implement Optionally, the anti-BCMA antibody or antigen-binding fragment thereof is detectably labeled. The kit.

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