Trispecific antibody, pharmaceutical composition and kit comprising the same, cell expressing the same, synthetic polynucleotide encoding the same, and generating method and use thereof

Abstract

This document provides multispecific antibodies that bind to BCMA, GPRC5D, and CD3, and their multispecific antigen-binding fragments. It also describes the associated polynucleotides encoding the provided multispecific antibodies or multispecific antigen-binding fragments, the cells expressing the provided multispecific antibodies or multispecific antigen-binding fragments, and the associated vectors and detectably labeled multispecific antibodies or multispecific antigen-binding fragments. Furthermore, methods for generating and using the provided multispecific antibodies and multispecific antigen-binding fragments are described.

Description

Technical field

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 149,921 filed on February 16, 2021. The entire contents of the aforementioned applications are incorporated herein by reference in their entirety.

[0003] The disclosure provided herein relates to multispecific antibodies that bind B-cell maturation antigen (BCMA), G protein-coupled receptor class C group 5 member D (GPRC5D), determinant 3 (CD3), BCMA-binding Monoclonal antibodies, and methods of producing and using said antibodies.

Prior Technology

[0004] Multiple myeloma (MM) is the second most common hematological malignancy and accounts for 2% of all cancer deaths. MM is a heterogeneous disease, and most are caused by chromosomal translocations, especially t(11; 14), t(4; 14), t(8; 14), del(13), del(17 ) (Drach et al., (1998) Blood 92(3):802-809; Gertz et al., (2005) Blood 106(8):2837-2840; Facon et al., (2001) Blood 97(6):1566 -1571). Patients affected by MM may experience a variety of disease-related symptoms resulting from bone marrow infiltration, bone destruction, renal failure, immune insufficiency, and the psychological burden of a cancer diagnosis. As of 2006, the 5-year relative survival rate for MM was approximately 34%, highlighting that MM is a difficult-to-treat disease for which there is currently no curative option.

[0005] B cell maturation antigen (also known as BCMA, CD269, TNFRSF17 (UniProt Q02223)) is a member of the tumor necrosis receptor superfamily (tumor necrosis receptor superfamily), which is preferentially expressed in differentiated plasma cells [Laabi et al. (1992) EMBO J 11(11):3897-3904; Madry et al., (1998) Int Immunol 10(11):1693-1702]. BCMA is a non-glycosylated type I transmembrane protein involved in the maturation, growth and survival of B cells. BCMA is a receptor for the following two ligands in the TNF superfamily: APRIL (a proliferation-inducing ligand, also known as CD256, TNFSF13), which is a high-affinity ligand of BCMA; and B cell activation factor BAFF (also known as THANK, BlyS, B-lymphocyte-stimulating factor, TALL-1, and zTNF4), which are low-affinity ligands of BCMA. APRIL and BAFF show structural similarity and overlap, but have different receptor binding specificities. The negative regulator TACI also binds to both BAFF and APRIL. Coordinated binding of APRIL and BAFF to BCMA and / or TACI activates transcription factor NF-κB and increases pro-survival (pro-survival) Bcl-2 family members (such as Bcl-2, Bcl-xL, Bcl-w, Mcl- 1. The expression of A1), and down-regulate the expression of pro-apoptotic factors (such as Bid, Bad, Bik, Bim, etc.), thereby inhibiting cell apoptosis and promoting survival. This combined effect promotes B cell differentiation, proliferation, survival, and antibody production (as reviewed in Rickert RC et al., Immunol Rev (2011) 244(1): 115-133). Consistent with this finding, BCMA also supports the growth and survival of malignant human B cells, including multiple myeloma (MM) cells. Novak et al. found that MM cell lines and freshly isolated MM cells expressed BCMA and TACI proteins on their cell surfaces and had variable BAFF-R protein expression on their cell surfaces (Novak et al., (2004) Blood 103(2):689-694).

[0006] The use of anti-BCMA antibody to treat lymphoma and multiple myeloma is mentioned in WO2002066516 and WO2010104949. Antibodies against BCMA are described eg in Gras M-P. et al., Int Immunol. 7 (1995) 1093-1106, WO200124811, and WO200124812. However, despite the fact that BCMA, BAFF-R and TACI (ie B cell receptors belonging to the TNF receptor superfamily) and their ligands BAFF and APRIL are the subject of therapies against cancer, more options are needed for Treat such medical conditions.

[0007] G protein-coupled receptor class C group 5 member D (GPRC5D) is an orphan, atypical class C GPCR that was first identified in 2001 (Bräuner-Osborne et al., Biochim Biophys Acta. 1518(3) :237-248, 2001). GPRC5D and the other group 5 GPCRs have an unusually short amine-terminal region for C receptors and are thus expected to be similar in conformation to class A receptors. In this regard, they are unique and share sequence homology to class C GPCRs and a predicted structural topology comparable to class A receptors. The functional consequences of GPRC5D activation have not been described and the ligand remains unknown. The gene has three exons and is located on human chromosome 12p13.3. The GPRC5D receptor is highly conserved among various species and shares 92% identity with cynomolgus monkey GPRC5D.

[0008] WO2016090329, WO2018017786, WO2018147245, and WO2019154890 mentioned the use of anti-GPRC5D antibodies for the treatment of multiple myeloma. However, despite the fact that GPRC5D is amenable to therapy in the fight against cancer, further options for the treatment of such medical conditions are still needed.

[0009] GPRC5D mRNA is mainly expressed in all malignant plasma cells from MM patients (Atamaniuk JA et al., Eur J Clin Invest 42(9) 953-960; 2012; Frigyesi-blood and Cohen et al., Hematology 18(6) : 348-35; 2013). GPRC5D expression is variable between patients and correlates well with plasma cell burden and genetic aberrations such as Rb-1 loss (Atamaniuk JA et al, Eur J Clin Invest 42(9) 953-960; 2012).

[0010] Colony resistance is a common mechanism in relapsed and refractory myeloma. Targeting more than one myeloma tumor antigen and engaging T cells resulted in efficient killing of malignant plasma cells and minimal residual disease (MRD) negativity. Dual BCMA and GPRC5D targeting enhances antibody affinity and potency, maximizes tumor suppression in the presence of heterogeneous cell populations, prevents tumor antigen escape (e.g., captures MM cells that express BCMA or GPRC5D deficient alone), improves tumor efficacy, And can alleviate the potential of cytokine release syndrome (CRS). Accordingly, there is a need for therapeutic antibodies targeting both BCMA and GPRC5D for the treatment of multiple myeloma and / or related medical conditions.

Content of invention

[0011] In one aspect, provided herein are multispecific antibodies, and multispecific antigen-binding fragments thereof, that specifically bind to or specifically bind to BCMA, GPRC5D, and CD3. In some embodiments, provided herein are trispecific antibodies, and trispecific antigen-binding fragments thereof, that specifically bind to or specifically bind to BCMA, GPRC5D, and CD3. Also described are related polynucleotides capable of encoding the provided BCMA x GPRC5D x CD3 multispecific antibodies or multispecific antigen-binding fragments, cells expressing the provided antibodies or multispecific antigen-binding fragments, and associated vectors and Detectably labeled multispecific antibody or multispecific antigen-binding fragment. In addition, methods of using the provided multispecific antibodies are described. For example, such BCMA x GPRC5D x CD3 multispecific antibodies and multispecific antigen-binding fragments are useful in the treatment of cancer (e.g., BCMA and / or GPRC5D expressing cancers); such BCMA x GPRC5D x CD3 multispecific antibodies It can be used to diagnose or monitor the progression, regression, or stabilization of BCMA and / or GPRC5D-expressing cancer; to determine whether a patient should undergo cancer treatment; or to determine whether a subject suffers from BCMA and / or GPRC5D-expressing cancer, and therefore Treatment with BCMA and / or GPRC5D specific anti-cancer therapeutics such as the BCMA x GPRC5D x CD3 multispecific antibodies described herein may be suitable. BCMA x GPRC5D x CD3 Multispecific Antibody

[0012] Described herein are isolated multispecific antibodies that bind BCMA, GPRC5D and CD3 ("BCMA x GPRC5D x CD3 multispecific antibodies") and multispecific antigen-binding fragments thereof.

[0013] In a preferred embodiment, the BCMA x GPRC5D x CD3 multispecific antibody or antigen-binding fragment is a trispecific antibody or antigen-binding fragment. In some embodiments, the isolated BCMA x GPRC5D x CD3 trispecific antibody or trispecific binding fragment thereof comprises: (a) a first antigen binding arm comprising a first heavy chain variable domain (VH1 ) and A first light chain variable domain (VL1); (b) a second antigen binding arm comprising a second heavy chain variable domain (VH2) and a second light chain variable domain (VL2); and (c) a third An antigen binding arm comprising a third heavy chain variable domain (VH3) and a third light chain variable domain (VL3). In some embodiments, the first antigen binding arm binds to an epitope on CD3, the second antigen binding arm binds to an epitope on GPRC5D, and the third antigen binding arm binds to an epitope on BCMA.

[0014] In some embodiments, the first antigen-binding arm of the trispecific antibody, or trispecific binding fragment thereof, comprises a first heavy chain portion (HC1) and a light chain portion, the first heavy chain portion comprising The VH1, the light chain portion comprises the VL1. The VH1 and the VL1 form a first antigen binding domain that binds a first antigen. The second antigen binding arm of the trispecific antibody or trispecific binding fragment thereof comprises a second heavy chain portion (HC2) comprising the VH2. The VH2 of the HC2 forms a second antigen binding domain that binds a second antigen. The HC1 or the HC2 is further coupled to the third antigen binding arm comprising the VH3 forming a third antigen binding domain that binds a third antigen. The HC1 and HC2 each optionally comprise a fragment crystallizable (Fc) domain, wherein the Fc domain comprises constant heavy chain region 2 (CH2) and CH3. In some embodiments, the first antigen is cluster of differentiation 3 (CD3), and the second antigen is B cell maturation antigen (BCMA), and the third antigen is a G protein-coupled receptor family C group 5 member D (GPRC5D). In some embodiments, the first antigen is cluster of differentiation 3 (CD3), and the second antigen is G protein-coupled receptor family C group 5 member D (GPRC5D), and the third antigen is B cell maturation Antigen (BCMA). Some aspects of the BCMA x GPRC5D x CD3 trispecific antibody, or trispecific binding fragments thereof, are further described in the Embodiments and Examples sections below.

[0015] In some embodiments, the BCMA binding arm binds human BCMA but does not bind cynomolgus monkey BCMA. In some embodiments, the BCMA binding arm binds to an epitope comprising one or more residues from the BCMA extracellular domain (ECD). In some embodiments, the BCMA-binding arm (or "BCMA-specific arm") of the BCMA x GPRC5D x CD3 multispecific antibody is derived from a BCMA antibody described herein (e.g., derived from from antibodies with the CDR sequences listed in Table 1).

[0016] In some embodiments, the GPRC5D-specific arm of the multispecific antibody binds to human GPRC5D but does not bind to cynomolgus monkey GPRC5D. In some embodiments, the GPRC5D-specific arm of the BCMAxGPRC5DxCD3 multispecific antibodies or antigen-binding fragments binds the extracellular domain of human GPRC5D. In some embodiments, the GPRC5D-binding arm (or "GPRC5D-specific arm") of the BCMA x GPRC5D x CD3 multispecific antibody is derived from a GPRC5D antibody described herein (e.g., derived from Antibodies with the CDR sequences listed).

[0017] Redirecting T lymphocytes to MM cells expressing BCMA and / or GPRC5D via the TCR / CD3 complex represents an attractive alternative. The TCR / CD3 complex system of T lymphocytes consists of TCR alpha (α) / beta (β) or TCR gamma (γ) / deta (δ) heterodimers, and invariant CD3 co-expressed on the cell surface Subunits (labeled gamma (γ), deta (δ), epsilon (ε), zeta (ζ), and ata (η)). In some embodiments, a multispecific antibody or multispecific antigen-binding fragment described herein binds to CD3ε. In some embodiments, the CD3-binding arm (or "CD3-specific arm") of the BCMAxGPRC5DxCD3 multispecific antibody is derived from monoclonal antibody CD3B376. In some embodiments, the CD3-binding arm (or "CD3-specific arm") of the BCMA x GPRC5D x CD3 multispecific antibody is derived from monoclonal antibody SP34, which is a mouse IgG3 / Lambda isotype. (K.R. Abhinandan and A. C. Martin, 2008. Mol. Immunol. 45, 3832-3839). In some embodiments, the CD3 binding arm of the BCMA x GPRC5D x CD3 multispecific antibody comprises the heavy chain CDR and / or light chain CDR described in Table 3 or any VH domain and / or selected from Table 3 Any VL domain.

[0018] In some embodiments, the BCMA, GPRC5D, and / or CD3-specific arms of the BCMA x GPRC5D x CD3 multispecific antibodies or antigen-binding fragments are IgG, or derivatives thereof. IgG classes are divided into four isotypes in humans: IgGl, IgG2, IgG3 and IgG4. The amino acid sequences of their Fc regions share more than 95% homology, but the amino acid composition and structure of the hinge region show major differences. The Fc region mediates effector functions such as antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). In ADCC, the Fc region of an antibody binds to Fc receptors (FcγRs) on the surface of immune effector cells, such as natural killer cells and macrophages, resulting in phagocytosis or lysis of target cells. In CDC, antibodies kill target cells by triggering the complement cascade on the cell surface.

[0019] In many therapeutic antibody applications, Fc-mediated effector functions are not part of the mechanism of action. Effector functions of these Fc mediators may be deleterious and may pose a safety risk by causing off-mechanism toxicity. Modification of effector functions can be achieved by engineering the Fc region to reduce its binding to FcyRs or complement factors. IgG binding to activating (FcyRI, FcyRIIa, FcyRIIIa, and FcyRIIIb) and inhibitory (FcyRIIb) FcyRs or the first component of complement (C1q) depends on residues located in the hinge region and the CH2 domain. Mutations have been introduced into IgGl, IgG2 and IgG4 to reduce or silence Fc functionality.

[0020] In one embodiment, the antibody comprises an Fc region having one or more of the following properties: (a) reduced effector function when compared to a parental Fc; (b) for FcγRI, FcγRIIa, FcγRIIb, FcγRIIIb, and / or have reduced affinity for FcyRIIIa, (c) reduced affinity for FcyRI, (d) reduced affinity for FcyRIIa, (e) reduced affinity for FcyRIIb, (f) reduced affinity for FcyRIIIb, or (g) reduced affinity for FcyRIIIa affinity is reduced.

[0021] In some embodiments, the CD3-specific antibody or antigen-binding fragment from which the CD3-specific arm of the multispecific antibody is derived is IgG, or a derivative thereof. In some embodiments, the CD3-specific antibody or antigen-binding fragment from which the CD3-specific arm of the multispecific antibody is derived is IgGl, or a derivative thereof. In some embodiments, for example, the Fc region of the CD3-specific IgGl antibody from which the CD3 binding arm is derived comprises L234A, L235A, and D265S substitutions in the Fc region. In some embodiments, the CD3-specific antibody or antigen-binding fragment from which the CD3-specific arm of the multispecific antibody is derived is IgG4, or a derivative thereof. In some embodiments, for example, the Fc region of the CD3-specific IgG4 antibody from which the CD3 binding arm is derived comprises S228P, L234A, L235A, F405L, and R409K substitutions in the Fc region. In some embodiments, the CD3-specific antibody or antigen-binding fragment from which the CD3-specific arm of the multispecific antibody is derived binds CD3ε on primary human T cells and / or primary cynomolgus T cells. In some embodiments, the CD3-specific antibody or antigen-binding fragment from which the CD3-specific arm of the multispecific antibody is derived activates primary human CD4+ T cells and / or primary cynomolgus CD4+ T cells.

[0022] In addition to the BCMA x GPRC5D x CD3 multispecific antibody, a polynucleotide sequence capable of encoding the BCMA x GPRC5D x CD3 multispecific antibody is also provided. In some embodiments, providing the one or more CDRs of the heavy chain variable domain encoding each antigen binding arm of the BCMAxGPRC5DxCD3 trispecific antibody or trispecific binding fragment and / or the light chain may An isolated synthetic polynucleotide of the one or more CDRs of a variable domain.

[0023] In some embodiments, there is provided a vector encoding one or more heavy chain variable domains and / or one or more light chain variable domains of a BCMA x GPRC5D x CD3 trispecific antibody or trispecific binding fragment Isolated synthetic polynucleotides. In some embodiments, isolated synthesis of one or more peptide chains encoding the first, second, and / or third antigen-binding arms of a BCMAxGPRC5DxCD3 trispecific antibody or trispecific binding fragment is provided sexual polynucleotides. Also provided are vectors comprising such polynucleotides, such as cells expressing the BCMAxGPRC5DxCD3 multispecific antibodies provided herein. In another embodiment, isolated cells expressing the multispecific antibody or multispecific binding fragment are provided. Cells capable of expressing the disclosed vectors are also described. Such cells may be mammalian cells (such as 293 cells, 293F cells, CHO cells), insect cells (such as Sf7 cells), yeast cells, plant cells, or bacterial cells (such as E. coli). The antibodies can also be produced by fusion of tumor cells. In some embodiments, methods for producing the BCMAxGPRC5DxCD3 trispecific antibody or trispecific binding fragment by culturing cells are provided.

[0024] Further provided herein are pharmaceutical compositions comprising the BCMA x GPRC5D x CD3 multispecific antibodies or antigen-binding fragments and pharmaceutically acceptable carriers. Method of using BCMA x GPRC5D x CD3 multispecific antibody

[0025] Also disclosed are methods of using the BCMA x GPRC5D x CD3 multispecific antibodies and multispecific antigen-binding fragments thereof. For example, the BCMA x GPRC5D x CD3 multispecific antibodies and multispecific antigen-binding fragments thereof can be used to treat GPRC5D and / or BCMA expressing cancers in a subject in need thereof. In some embodiments, the GPRC5D and / or BCMA expressing cancer is lymphoma, such as multiple myeloma, including smoldering multiple myeloma (SMM). In some embodiments, the GPRC5D and / or BCMA expressing cancer is a relapsed or refractory form of lymphoma, such as a relapsed or refractory form of multiple myeloma.

[0026] The method for treating GPRC5D and / or BCMA-expressing cancer in a subject in need thereof comprises administering to the subject a therapeutically effective amount of the BCMA x GPRC5D x CD3 multispecific antibody or its multispecific antigen Combine fragments. In some embodiments, the subject is a mammal, preferably a human. In a preferred embodiment, there is provided a method for treating a subject with cancer by administering to a patient in need thereof a therapeutically effective amount of the BCMAxGPRC5DxCD3 trispecific antibody or trispecific antigen binding Fragments for a period of time sufficient to treat the cancer.

[0027] Further provided herein is a method for inhibiting cancer cell growth or proliferation, which is to inhibit the growth of cancer cells by administering a therapeutically effective amount of the BCMA x GPRC5D x CD3 trispecific antibody or trispecific binding fragment or hyperplasia.

[0028] Also provided herein are methods of redirecting T cells to GPRC5D and / or BCMA expressing cancer cells by administering a therapeutically effective amount of the BCMAxGPRC5DxCD3 trispecific antibody or trispecific binding fragments to redirect T cells to cancer.

[0029] Those skilled in the art will appreciate that methods of using the described BCMA x GPRC5D x CD3 multispecific antibodies and multispecific antigen-binding fragments thereof may be specified in a medical-use format, e.g., in BCMA x GPRC5D x CD3 multispecific Antibody and multispecific antigen-binding fragment forms are useful in the treatment of diseases as defined herein, in particular in the treatment of cancer. Those skilled in the art will also appreciate that the methods of using the described BCMA x GPRC5D x CD3 multispecific antibodies and multispecific antigen-binding fragments thereof can be designated by the so-called Swiss type, e.g. by BCMA x GPRC5D x CD3 Forms of use of multispecific antibodies and multispecific antigen-binding fragments are for the manufacture of a medicament for the treatment of a disease as defined herein, in particular for the manufacture of a medicament for the treatment of cancer. This applies throughout this disclosure. BCMA x GPRC5D x CD3 Specific Antibody Kit

[0030] Described herein are panels comprising the disclosed BCMA x GPRC5D x CD3 multispecific antibodies. The kits can be used to perform methods using the BCMAxGPRC5DxCD3 multispecific antibodies provided herein, or other methods known to those of ordinary skill in the art. In some embodiments, the kit can include the antibodies described herein and agents for treating GPRC5D and / or BCMA expressing cancers. Accordingly, the kit may comprise one or more of the multispecific antibodies (or multispecific antigen-binding fragments thereof) described herein and a container for holding the antibodies or fragments when not in use, and / or Instructions for use of the antibody or fragment, antibody or fragment immobilized to a solid support, and / or detectably labeled forms of the antibody or fragment are as described herein. BCMA specific antibody

[0031] Also provided herein are antibodies and antigen-binding fragments thereof that bind to BCMA. Also described are related polynucleotides capable of encoding the provided BCMA-specific antibodies and antigen-binding fragments, cells expressing the provided antibodies and antigen-binding fragments, and associated vectors and detectably labeled antibodies and antigen-binding fragments . Additionally, methods of using the provided antibodies and antigen-binding fragments are described. For example, such BCMA-specific antibodies and antigen-binding fragments can be used to treat cancer (for example, BCMA-expressive cancer); such BCMA-specific antibodies and antigen-binding fragments can be used to diagnose or monitor the progression and regression of BCM-expressive cancer , or stable; used to determine whether a patient should undergo cancer treatment; or used to determine whether a subject suffers from BCMA-expressing cancer and thus can use BCMA-specific anti-cancer therapeutic agents such as the multispecific anti-BCMA and CD3 described herein Antibodies for treatment. Some aspects of the BCMA-specific antibodies or antigen-binding fragments are further described in the Embodiments and Examples section below. Methods of using BCMA-specific antibodies

[0032] Also disclosed are methods of using the BCMA-specific antibodies or antigen-binding fragments. Specific antibodies used in the methods discussed in this section include antibodies with the CDR sets of antibodies described in Table 1 (eg, BCMB519). For example, the antibodies or antigen-binding fragments can be used to treat cancer, for example by interfering with BCMA-receptor interactions, or wherein the antibody is conjugated to a toxin, thereby targeting the toxin to the BCMA expressing cancer. In addition, these antibodies or antigen-binding fragments can be used to detect the presence of BCMA in biological samples such as blood or serum; to quantify the amount of BCMA in biological samples such as blood or serum; to diagnose BCMA expressing cancers ; determining a method of treating a subject suffering from cancer; or monitoring the progression of a BCMA expressing cancer in a subject. In some embodiments, the BCMA expressing cancer may be a lymphoma, such as multiple myeloma (MM), including smoldering multiple myeloma (SMM). In some embodiments, the BCMA expressing cancer is a relapsed or refractory form of lymphoma, such as a relapsed or refractory form of multiple myeloma. The method can be performed before the subject receives treatment for BCMA expressing cancer, such as treatment with multispecific antibodies directed against BCMA and CD3. In addition, the methods can be performed after the subject has received treatment for a BCMA expressing cancer, such as treatment with a multispecific antibody to BCMA and CD3 described herein.

[0033] The method of detecting BCMA in a biological sample comprises exposing the biological sample to one or more of the BCMA-specific antibodies or antigen-binding fragments described herein.

[0034] The methods of diagnosing BCMA-expressing cancer in a subject also involve exposing the biological sample to one or more of the BCMA-specific antibodies or antigen-binding fragments described herein; however, these methods also include quantifying the amount of BCMA present in the sample; comparing the amount of BCMA present in the sample to a known standard or reference sample; and used to determine whether the subject's BCMA level falls within a BCMA level associated with cancer .

[0035] Also described herein are methods of monitoring BCMA expressing cancer in a subject. The method comprises exposing the biological sample to one or more of the BCMA-specific antibodies or antigen-binding fragments described herein; quantifying the amount of BCMA present in the sample and bound by the antibody, or antigen-binding fragment thereof. the amount of BCMA present in the sample compared to a known standard or reference sample, or to the amount of BCMA in a similar sample previously obtained from the subject; and based on the amount of BCMA in the compared sample Differences were used to determine whether a subject's BCMA levels indicated cancer progression, regression, or stable disease.

[0036] A sample obtained or derived from a subject is a biological sample, such as urine, blood, serum, plasma, saliva, ascites, circulating cells, circulating tumor cells, cells that are not tissue associated ), tissue, surgically removed tumor tissue, biopsy, fine needle aspiration sample, or histological preparation.

[0037] The BCMA-specific antibodies or antigen-binding fragments may be labeled for use in the described methods or other methods known to those of ordinary skill in the art. For example, the antibodies described herein, or antigen-binding fragments thereof, can be labeled with radioactivity, fluorescent labels, epitope tags, biotin, chromophore labels, ECL labels, enzymes, ruthenium, In-DOTA, 111In-diethylenetriaminepentaacetic acid (DTPA), horseradish peroxidase (horseradish peroxidase), alkaline phosphatase and β-galactosidase, or poly-histidine or the like known in the art Wait for the mark to be marked. BCMA Specific Antibody Kit

[0038] Described herein are kits comprising the disclosed BCMA-specific antibodies or antigen-binding fragments thereof. The kits can be used to perform methods using the BCMA-specific antibodies or antigen-binding fragments provided herein, or other methods known to those of ordinary skill in the art. In some embodiments, the kit can include an antibody or antigen-binding fragment described herein, and a reagent for detecting the presence of BCMA in a biological sample. Accordingly, the kit may include one or more of the antibodies (or antigen-binding fragments thereof) described herein, a container for containing the antibody or fragment when not in use, instructions for use of the antibody or fragment, immobilization Antibodies or fragments to solid supports, and / or detectably labeled forms of such antibodies or fragments, as described herein.

Implementation

[0040] definition

[0041] Various terms related to aspects of the embodiments are used in various parts of the specification and claims. These terms are used in their original meanings in the technical field, unless otherwise indicated. Other specifically defined terms are to be interpreted in accordance with the definitions provided in this specification.

[0042] In this specification and the appended scope of claims, unless the text clearly states otherwise, the singular forms "one (a / an)" and "the (the)" all include plural references. Thus, for example, reference to "a cell" includes combinations and the like of two or more cells.

[0043] The term "about" as used herein when referring to a measurable value (such as amount, duration, and the like) is intended to cover variations within up to ± 10% of the specified value, if so The class mutates to be suitable for implementing the disclosed methods. Unless otherwise indicated, all numbers used in the specification and claims to express quantities of ingredients, properties (such as molecular weights, reaction conditions, etc.) should be understood as being modified by the word "about" in all cases. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present invention. In any case, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claim, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding calculations.

[0044] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contain certain errors necessarily resulting from the standard deviation found in their individual testing measurements.

[0045] "Isolated" means that a biological component (such as a nucleic acid, peptide, or protein) has been separated from other biological components (i.e., other chromosomal and extrachromosomal DNA) in the organism in which the component naturally occurs. and RNA, and proteins) are substantially separated from, produced separately from, or purified away from, such other biological components. Nucleic acids, peptides, and proteins that have been "isolated" thus include nucleic acids and proteins purified by standard purification methods. "Isolated" nucleic acids, peptides, and proteins can be part of a composition and still be isolated, so long as the composition is not part of the nucleic acid, peptide, and protein's native environment. The term also encompasses nucleic acids, peptides and proteins produced by recombinant expression in host cells as well as chemically synthesized nucleic acids. As used herein, an "isolated" antibody or antigen-binding fragment means an antibody or antigen-binding fragment that is substantially free of other antibodies or antigen-binding fragments with different antigen specificities (e.g., specifically binds to BCMA The isolated antibody system does not substantially contain antibodies that specifically bind to antigens other than BCMA). However, isolated antibodies that specifically bind to an epitope, isoform or variant of BCMA or GPRC5D may have cross-reactivity to other related antigens, e.g., related antigens from other species, such as BCMA or GPRC5D species homologues .

[0046] "polynucleotide (polynucleotide)" is synonymously referred to as "nucleic acid molecule (nucleic acid molecule)", "nucleotide (nucleotide)", or "nucleic acid (nucleic acid)", which refers to any polyribose nucleus Nucleotides or polydeoxyribonucleotides, which may be unmodified RNA or DNA or modified RNA or DNA. "Polynucleotide" includes, but is not limited to, single- and double-stranded DNA, DNA that is a mixture of single- and double-stranded regions, single- and double-stranded RNA, and RNA that is a mixture of single- and double-stranded regions , hybrid molecules comprising DNA and RNA which may be single-stranded or (more typically) double-stranded or a mixture of single- and double-stranded regions. In addition, "polynucleotide" refers to a triple-stranded region comprising RNA or DNA or both RNA and DNA. The term polynucleotide also includes DNA or RNA containing one or more modified bases and DNA or RNA having a backbone modified for stability or for other reasons. "Modified" bases include, for example, tritylated bases and unusual bases such as inosine. Various modifications can be made to DNA and RNA; thus, "polynucleotide (polynucleotide)" includes chemically, enzymatically, or metabolically modified forms of polynucleotides typically found in nature, as well as DNA and DNA unique to viruses and cells. The chemical form of RNA. "Polynucleotide" also includes relatively short strands of nucleic acid, commonly referred to as oligonucleotides.

[0047] The meaning of "substantially the same" can vary depending on the context in which the term is used. Because of the natural sequence variation that may exist in the heavy and light chains and the genes encoding them, it is expected that some degree of variation will be found in the amino acid sequence or genes encoding the antibodies or antigen-binding fragments described herein, such that Variation has little effect on their unique binding properties (eg, specificity and affinity). This expectation is due in part to the degeneracy of the genetic code, and to the evolutionary success of conservative amino acid sequence variations that do not appreciably alter the nature of the encoded protein. Thus, "substantially the same" in reference to nucleic acid sequences means that there is at least 65% identity between two or more sequences. Preferably, the term refers to at least 70% identity, more preferably at least 80% identity, more preferably at least 85% identity, more preferably at least 90% identity between two or more sequences , more preferably at least 91% identity, more preferably at least 92% identity, more preferably at least 93% identity, more preferably at least 94% identity, more preferably at least 95% identity, more preferably at least 96% identity, more preferably at least 97% identity, more preferably at least 98% identity, and more preferably at least 99% or more identity. The percent identity between two sequences is a function of the number of identity positions shared by the sequences (i.e. % Homology = Identity Position # / Total Position # x 100) and will need to be imported to optimally align the The number of gaps in the two sequences and the length of each gap were taken into consideration. The percent identity between two nucleotide or amino acid sequences can be determined using, for example, the algorithm of E. Meyers and W. Miller, Comput. Appl. Biosci 4, 11-17 (1988), which incorporates In the ALIGN program (version 2.0), it uses a PAM120 weighted residue table, a gap length penalty of 12, and a gap penalty of 4. Additionally, the percent identity between two amino acid sequences can be determined using the algorithm of Needleman and Wunsch, J. Mol. Biol. 48, 444-453 (1970).

[0048] The degree of variation that does not substantially affect the function of the protein occurs within the amino acid sequence of a protein much less than in a nucleic acid sequence because the same degeneracy theory does not apply to amino acid sequences. Thus, "substantially the same" when referring to an antibody or antigen-binding fragment means that the antibody or antigen-binding fragment is 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity. Other embodiments include antibodies or antigen-binding fragments that have frameworks, scaffolds, or other non-binding regions that do not share significant identity with the antibodies and antigen-binding fragments described herein, but do include one or more CDRs or other endowing Sequences that are required for binding and that are 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to such sequences described herein.

[0049] A "clone" is a population of cells derived by mitosis from a single cell or from a common ancestor. A "cell line" is a primary cell colony capable of stable growth in vitro for many generations. In some of the examples provided herein, cell lines are transformed by DNA transfection of cells.

[0050] The terms "express" and "produce" are used synonymously herein and refer to the biosynthesis of a gene product. These terms encompass the transcription of a gene into RNA. These terms also encompass the translation of RNA into one or more polypeptides, and further encompass all naturally occurring post-transcriptional and post-translational modifications. Expression or production of antibodies or antigen-binding fragments thereof can be within the cytoplasm of the cell, or into the extracellular environment, such as the growth medium of cell culture.

[0051] The term "treating or treatment" means any successful or indication of success in alleviating or ameliorating an injury, pathological change or condition, including any objective or subjective parameter, such as reduction, relief or regression of symptoms or reduction of the condition It is more tolerable for the patient, slows degeneration or the rate of decline, makes the end of degeneration less debilitating, improves the subject's physical or mental health, or prolongs survival. Treatment can be assessed by objective or subjective parameters; including the results of a physical, neurological, or psychiatric assessment.

[0052] "Effective amount" or "therapeutically effective amount" refers to the effective dose and amount of time required to achieve the desired therapeutic result. A therapeutically effective amount of a BCMA x GPRC5D x CD3 antibody can vary depending on various factors, such as the individual's disease state, age, sex, and weight, and the ability of the antibody to elicit a desired response in the individual. A therapeutically effective amount is also one in which any toxic or detrimental effects of the antibody or antibody portion are outweighed by the therapeutically beneficial effects.

[0053] "Antibody" refers to all isotypes of immunoglobulins (IgG, IgA, IgE, IgM, IgD, and IgY), including various monomeric, polymeric, and chimeric forms, unless otherwise specified. Specifically encompassed by the term "antibody" are polyclonal antibodies, monoclonal antibodies (mAbs), and antibody-like polypeptides, such as chimeric antibodies and humanized antibodies.

[0054] The term "antigen-binding arm" refers to a portion comprising an antigen-binding domain that binds to an antigen (e.g., BCMA, GPRC5D, or CD3), and optionally one or more other antibody domains ( For example, Fc domain).

[0055] The term "antigen-binding fragment" refers to a fragment comprising the antigen-binding arm of the antigen-binding domain. Antigen-binding fragments include those provided by any known technique, such as enzymatic cleavage, peptide synthesis, and recombinant techniques. Some antigen-binding fragments consist of portions of an intact antibody that retain the antigen-binding specificity of the parent antibody molecule. For example, an antigen-binding fragment may comprise at least one variable region (heavy or light chain variable region) or one or more CDRs of an antibody known to bind a particular antigen. Examples of suitable antigen-binding fragments include, but are not limited to, diabodies and single chain molecules as well as Fab, F(ab')2, Fc, Fabc, and Fv molecules, single chain (Sc) antibodies, individual antibody light chains , individual antibody heavy chains, antibody chains or CDRs and other proteins, chimeric fusions between protein scaffolds, heavy chain monomers or dimers, light chain monomers or dimers, composed of one heavy chain and one light chain Constituent dimers, monovalent fragments consisting of VL, VH, CL and CH1 domains, or monovalent antibodies as described in WO2007059782, bivalent fragments comprising two Fab fragments connected by a disulfide bridge in the hinge region , Fd fragments basically composed of VH and CH1 domains; Fv fragments and dAb fragments mainly composed of VL and VH domains of antibody single arms (Ward et al., Nature 341, 544-546 (1989)) (the main Composed of VH domains and also known as domain antibodies (Holt et al; Trends Biotechnol. 2003 Nov.; 21(11):484-90); camelid or nanobodies (Revets et al; Expert Opin Biol Ther. 2005 Jan.; 5(1):111-24); isolation of complementarity determining regions (CDRs), and the like; and trispecific antibodies formed from antibody fragments. All antibody isotypes can be used to produce antigen-binding fragments. In addition, antigen-binding fragments may include non-antibody protein frameworks such as protein scaffolds to successfully place polypeptide segments in positions that confer affinity for a given antigen of interest. Antigen-binding fragments can be produced recombinantly, or by enzymatic or chemical cleavage of intact antibodies. The phrase "an antibody or antigen-binding fragment thereof" may be used to mean that the specified antigen-binding fragment incorporates one or more amino acid segments of the antibody to which the phrase refers.

[0056] The term "antigen-binding domain" refers to the protein structure of the antigen-binding arm that exhibits binding affinity for a specific antigen. The protein structure is mediated by the complementarity determining regions (CDRs) of the antigen binding domain.

[0057] The term "CDR" and its plural "CDRs" refer to complementarity-determining regions (CDRs), three of which constitute the binding features of the light chain variable region (CDRL1, CDRL2, and CDRL3) and three of which constitute the heavy chain variable region. Binding features (CDRH1, CDRH2 and CDRH3). CDRs contribute to the functional activity of the antibody molecule and are separated by amino acid sequences comprising scaffold or framework regions. There are different classification and numbering systems for the exact defining CDR boundaries and lengths. Thus CDRs may be referred to herein by Kabat, Chothia, AbM, contact or any other boundary definition. Despite different boundaries, each of these systems has some degree of overlap in the composition of so-called "hypervariable regions" within variable sequences. Thus the CDR definitions according to these systems may differ with regard to the length of adjacent architectural regions and the border regions. See, eg, Kabat et al., Sequences of Proteins of Immunological Interest, 5th ed. NIH Publication No. 91-3242 (1991); Chothia et al., "Canonical Structures For the Hypervariable Regions of Immunoglobulins," J. Mol. Biol. 196 :901 (1987); and MacCallum et al., "Antibody-Antigen Interactions: Contact Analysis and Binding Site Topography," J. Mol. Biol. 262:732 (1996)), each of which is hereby incorporated by reference in its entirety incorporated into this article.

[0058] In general, CDRs form ring structures that can be classified as canonical structures. The term "canonical structure" refers to the backbone configuration adopted by the antigen binding (CDR) loop. From comparative structural studies, five of the six antigen-binding loops were found to have only limited repertoires available. Each canonical structure can be characterized by the torsion angle of the polypeptide backbone. Accordingly, corresponding loops between antibodies may have very similar three-dimensional structures despite high amino acid sequence variability in large portions of the loops (Chothia et al., "Canonical Structures For the Hypervariable Regions of Immunoglobulins," J. Mol. Biol. 196:901 (1987); Chothia et al., "Conformations of Immunoglobulin Hypervariable Regions," I 342:877 (1989); Martin and Thornton, "Structural Families in Loops of Homologous Proteins: Automatic Classification, Modeling and Application to Antibodies," J. Mol. Biol.263:800 (1996), the full texts of which are incorporated herein by reference. In addition, there is a gap between the loop structure adopted and the amino acid sequence around it. A relationship. The configuration of a particular canonical class is determined by the length of the loop and the amino acid residues at key positions within the loop and within the reserved framework (i.e. outside the loop). Therefore, based on these key amine The presence of amino acid residues is used to assign specific canonical classes.

[0059] The term "polypeptide" is used interchangeably with the term "protein" and refers in its broadest sense to two or more subunit amino acids, amino acid analogs or peptidomimetics compounds of things. Subunits can be linked by peptide bonds. In another embodiment, subunits may be linked by other linkages, such as esters, ethers, and the like. The term "amino acid" as used herein refers to natural and / or non-natural or synthetic amino acids, including glycine and D and L optical isomers, amino acid analogs and pseudo Peptides. Peptides of three or more amino acids are often called oligopeptides if the peptide chain is very short. If the peptide chain is very long, the peptide is often called a polypeptide or protein. As used herein, the term "Fc" refers to the fragment crystallizable domain of an antibody, which comprises two constant heavy chain (CH) regions, CH2 and CH3. Herein, the amino acid residues of the Fc region are generally numbered according to the EU numbering scheme (Edelman, G.M. et al., Proc. Natl. Acad. USA, 63, 78-85 (1969). PMID: 5257969). These residues can be identified according to alternative numbering schemes such as IMGT and Kabat (Kabat, E.A. et al., Sequences of proteins of immunological interest. Fifth Edition - US Department of Health and Human Services, NIH Publication n 91-3242, pp 662,680,689 (1991 )) number and are easily assigned, as would be readily understood by one of ordinary skill in the art. For example, L234 according to EU numbering can also be expressed as L247 according to Kabat.

[0060] When "specific binds / binds specifically" or its derivatives are used in the context of antibodies or antibody fragments, it means that the domains encoded by immunoglobulin genes or immunoglobulin gene fragments bind to the Focuses on one or more epitopes of a protein and does not preferentially bind other molecules in samples containing a mixed population of molecules. Typically, an antibody binds to a cognate antigen with a Kd of less than about 1 x 10-8M, as measured by a surface plasmon resonance assay or a cell binding assay. Phrases such as "[antigen]-specific" antibodies (eg, BCMA-specific antibodies) are intended to express that the recited antibody specifically binds the recited antigen. Herein, whenever the term "bind" is used, it is intended to encompass "specific binding" and the terms are interchangeable as desired.

[0061] The term "chimeric" as used herein refers to an antibody, or antigen-binding fragment thereof, having at least one variable domain derived from the amino acid sequence of an antibody from a non-human mammal, rodent, or reptile and the remainder of the antibody, or antigen-binding fragment thereof, is derived from a human.

[0062] A "vector" is a replicon, such as a plastid, bacteriophage, cosmid, or virus, into which another nucleic acid segment is operably inserted such that the Section copy or representation.

[0063] As used herein, the term "host cell" can be any type of cell, such as a primary cell, a cell in culture, or a cell from a cell line. In certain embodiments, the term "host cell" refers to a cell transfected with a nucleic acid molecule and the progeny or potential progeny of the cell. Progeny of the cell may not be identical to the parental cell transfected with the nucleic acid molecule due to, for example, mutations or environmental influences that occur in subsequent generations or when the nucleic acid molecule integrates into the genome of the host cell. The terms "expression" and "production" are used synonymously herein and refer to the biosynthesis of a gene product. These terms encompass the transcription of a gene into RNA. These terms also encompass the translation of RNA into one or more polypeptides, and further encompass all naturally occurring post-transcriptional and post-translational modifications.

[0064] The term "subject" refers to human and non-human animals, including all vertebrates, such as mammals and non-mammals, such as non-human primates, mice, rabbits, sheep, dogs, cats, horses , cattle, chickens, amphibians, and reptiles. In many embodiments of the methods, the subject is a human.

[0065] The term "redirecting / redirecting" as used herein refers to the efficient transfer of T cell activity from its inherent cognate specificity to GPRC5D and / or BCMA expressing antibodies by BCMA x GPRC5D x CD3 antibodies The responsiveness of cells.

[0066] "Sample" as used herein refers to a similar fluid, cell, or tissue isolated from a subject (e.g., surgically resected tumor tissue, biopsy, including fine-needle aspiration), as well as samples present in a subject. A general term for fluid, cells, or tissues within. In some embodiments, the sample is a biological fluid. Biological fluids are generally liquids at physiological temperatures and may include naturally occurring fluids present on, drawn from, expressed from, or otherwise extracted from a subject or biological source. Certain biological fluids are derived from specific tissues, organs, or localized areas while certain other biological fluids may be located more globally or systemically in a subject or biological source. Examples of biological fluids include blood, serum and serosal fluids, plasma, lymph, urine, saliva, cyst fluid, tears, feces, sputum, mucous membrane secretions of secretory tissues and organs, vaginal secretions, ascites (such as and non- Ascites related to solid tumors), pleural fluid, pericardial fluid, peritoneal fluid, peritoneal fluid and other body cavity fluids, bronchial lavage collection fluid and the like. Biological fluids can also include liquid solutions that come into contact with a subject or biological source, such as cell and organ culture media (including cell or organ conditioned media), lavage fluids, and the like. The term "sample" as used herein encompasses material taken from or present in a subject. Relevant aspects of the invention can be performed in vitro based on the desired isolated sample.

[0067] "Known standard (known standard)" can be a solution with known amount or concentration of GPRC5D and / or BCMA, wherein the solution can be a naturally occurring solution, such as from known patients with early, middle, late , progressive, or stable cancer, or the solution may be a synthetic solution, such as buffered water having a known amount of GPRC5D and / or BCMA diluted therein. Known standards described herein may include GPRC5D and / or BCMA isolated from a subject, recombinant or purified GPRC5D and / or BCMA protein, or GPRC5D and / or BCMA BCMA concentration values ​​associated with a disease condition.

[0068] The terms "B-cell maturation antigen" and "BCMA" as used herein include human B-cell maturation antigen, also known as BCMA, CD269, and TNFRSF17 (UniProt Q02223), which is a tumor necrosis A member of the receptor superfamily, preferentially expressed in differentiated plasma cells. The extracellular domain of human BCMA consists of amino acids 1 to 54 (or 5 to 51) according to UniProt. As used herein, the terms "antibody against BCMA, anti-BCMA antibody" relate to an antibody that specifically binds to BCMA.

[0069] The terms "G-protein coupled receptor family C group 5 member D (G-protein coupled receptor family C group 5 member D)" and "GPRC5D" specifically include the human GPRC5D protein, as described, for example, in GenBank accession numbers BC069341, NCBI reference sequence: NP_061124.1, and UniProtKB / Swiss-Prot accession number Q9NZD1 (see also Brauner-Osborne, H. et al., 2001, Biochim. Biophys. Acta 1518, 237-248).

[0070] The terms "cluster determinant 3" and "CD3" include multiple unit complexes of the human CD3 protein. The CD3 protein multiple subunit complex consists of 6 different polypeptide chains. These polypeptide chains include CD3 gamma chain (SwissProt P09693), CD3 delta chain (SwissProt P04234), two CD3 epsilon chains (SwissProt P07766), and a homodimer of CD3 zeta chain associated with T cell receptor alpha and beta chains. ) (SwissProt 20963). The term "CD3" includes any variants, isoforms and species homologues of CD3 which are naturally expressed by cells, including T cells, or which may be expressed on cells transfected with genes or cDNAs encoding these polypeptides, unless otherwise noted.

[0071] "BCMA x GPRC5D x CD3 antibody (BCMA x GPRC5D x CD3 antibody)" is a multispecific antibody, optionally a trispecific antibody, which comprises three different antigen-binding arms, one of which binds to the antigen BCMA , one binds to the antigen GPRC5D, while the other binds to CD3. A "BCMA x CD3 antibody" is a multispecific antibody, optionally a bispecific antibody, comprising two distinct antigen-binding arms, one of which binds to the antigen BCMA and the other binds to CD3. A "GPRC5D x CD3 antibody (GPRC5D x CD3 antibody)" is a multispecific antibody, optionally a bispecific antibody, which comprises two different antigen-binding arms, one of which binds to the antigen GPRC5D and the other specifically binds to CD3. The term "multispecific antibody" is used herein broadly and specifically encompasses antibodies with multiple epitope specificities. Multispecific antibodies include, but are not limited to, antibodies comprising a heavy chain variable domain (VH) and a light chain variable domain (VL), wherein the VHVL unit has polyepitopic specificity; having two or more VL and VH domains Antibodies wherein each VHVL unit binds to a different epitope; antibodies having two or more single variable domains, each single variable domain binding to a different epitope; full-length antibodies; and antibodies comprising one or more antibody fragments Antibodies and antibodies comprising covalently or non-covalently linked antibody fragments.

[0072] The multispecific antibody can be a bispecific antibody, a trispecific antibody, a bivalent antibody, or a similar molecule (for example, see PNAS USA90(14), 6444-8 (1993) for a description of bivalent antibodies) . The bispecific antibodies, trispecific antibodies, diabodies, and the like provided herein can bind any suitable target in addition to BCMA or a portion of GPRC5D. The term "bispecific antibody" is understood as an antibody having two different antigen-binding arms defined by different antibody sequences. The term "trispecific antibody" is understood as an antibody having three different antigen-binding arms defined by different antibody sequences. This can be understood as different target binding but also includes binding to different epitopes in one target.

[0073] A "reference sample" is a sample that can be compared to another sample, such as a test sample, to allow for characterizing the compared sample. A reference sample will have some characterized properties that can be used as a basis for comparison with the test sample. For example, a reference sample can be used as an indicator of GPRC5D or BCMA levels to indicate that a subject has cancer. A reference sample does not necessarily need to be analyzed together with a test sample, so in some cases a reference sample may be a value or range of values ​​that has been predetermined to characterize a given condition, such as GPRC5D or BCMA levels indicative of cancer in a subject. The term also includes samples for comparative purposes that are known to be associated with a physiological state or disease condition such as GPRC5D or BCMA expressing cancer, but have unknown amounts of GPRC5D or BCMA.

[0074] "Relapsed" refers to the return of a disease or signs and symptoms of a disease after a period of improvement following previous treatment with a therapeutic agent.

[0075] "Refractory" refers to a disease that does not respond to treatment. Refractory disease can be resistant to treatment prior to or when treatment is initiated, or refractory disease can become resistant during treatment.

[0076] The term "progression" as used in reference to the progression of a GPRC5D and / or BCMA expressing cancer includes a change in the cancer from a less severe state to a more serious state. This can include increased number or severity of tumors, increased extent of metastasis, increased rate of cancer growth or spread, and the like. For example, "the progression of colon cancer" includes the progression of the cancer from a less severe state to a more serious state, such as from stage I to stage II, from stage II to stage III wait.

[0077] The term "regression" as used in reference to regression of GPRC5D and / or BCMA expressing cancers includes a change in cancer from a more severe state to a less severe state. This can include a reduction in the number or severity of tumors, a reduction in the extent of metastasis, a reduction in the rate of cancer growth or spread, and the like. For example, "the regression of colon cancer" includes regression of the cancer from a more advanced state to a less advanced state, such as progression from stage III to stage II, from stage II to stage I, etc. .

[0078] The term "stable", as used in reference to stable GPRC5D and / or BCMA expressing cancers, is intended to describe that the disease state has not (or has not) changed significantly enough to be eliminated over a clinically relevant period. Thinking that the cancer is progressing or that the cancer is regressing.

[0079] The embodiments described herein are not limited to particular methods, reagents, compounds, compositions or biological systems, which can, of course, vary. multispecific antibody

[0080] Provided herein are multispecific antibodies, and trispecific binding fragments thereof, that bind to BCMA, GPRC5D, and CD3. Such antibodies or antibody fragments may allow for more specific targeting of particular subsets of cells compared to antibodies targeting only one or both of these targets.

[0081] This can be achieved, for example, by making a molecule comprising a first antigen-binding arm that binds to CD3, a second antigen-binding arm that binds to GPRC5D, and a third antigen-binding arm that binds to BCMA. The antigen binding arms may take any form that allows specific recognition of the target, for example the binding arm may be or may comprise a heavy chain variable domain, an Fv (a combination of heavy and light chain variable domains), a single chain Fv (scFv), Fab, binding domain based on fibronectin type III domain (such as from fibronectin, or based on a consensus sequence from fibronectin type III domain, or from solid tenascin, or based on a consensus sequence from the type III domain of tenascin, such as the Centyrin molecule from Janssen Biotech, Inc., see eg WO2010 / 051274 and WO2010 / 093627). In certain embodiments, the trispecific antibody comprises three antigen binding arms. In some embodiments, the trispecific antibody consists of antibodies (e.g., IgG format) fused to other antigen-binding arms, e.g., as single chain variable fragments, e.g., to one of the antibody's heavy chains or N or C-terminus of one of the light chains.

[0082] Accordingly, trispecific molecules comprising three different antigen binding arms that bind BCMA, GPRC5D and CD3, respectively, are provided.

[0083] In some embodiments, the BCMA x GPRC5D x CD3 multispecific antibody comprises (a) a first antigen-binding arm comprising a first heavy chain variable domain (VH1) and a first light chain variable domain ( VL1); (b) a second antigen binding arm comprising a second heavy chain variable domain (VH2) and a second light chain variable domain (VL2); and (c) a third antigen binding arm comprising a third Heavy chain variable domain (VH3) and third light chain variable domain (VL3).

[0084] In some embodiments, the first antigen binding arm binds to an epitope on CD3, the second antigen binding arm binds to an epitope on GPRC5D, and the third antigen binding arm binds to an epitope on BCMA bit.

[0085] In some embodiments, the first antigen-binding arm that binds CD3 comprises HCDR1, HCDR2, and HCDR3 of the VH1 of SEQ ID NO:8. In some embodiments, the first antigen-binding arm that binds CD3 comprises LCDR1, LCDR2, and LCDR3 of the VL1 of SEQ ID NO:7. In some embodiments, the first antigen-binding arm that binds CD3 comprises: HCDR1 comprising the amino acid sequence of GDSVFNNNAAWS (SEQ ID NO: 4), HCDR2 comprising the amino acid sequence of RTYYRSKWLYD (SEQ ID NO: 5) , and HCDR3 comprising the amino acid sequence of GYSSSFDY (SEQ ID NO: 6). In some embodiments, the first antigen-binding arm that binds CD3 comprises: LCDR1 comprising the amino acid sequence of TGTSSNIGTYKFVS (SEQ ID NO: 1), LCDR2 comprising the amino acid sequence of EVSKRPS (SEQ ID NO: 2) , and LCDR3 comprising the amino acid sequence of VSYAGSGTLL (SEQ ID NO: 3). In some embodiments, the first antigen-binding arm that binds CD3 comprises the VH1 of SEQ ID NO:8. In some embodiments, the first antigen-binding arm that binds CD3 comprises the VL1 of SEQ ID NO:7.

[0086] In some embodiments, the second antigen binding arm that binds GPRC5D comprises HCDR1, HCDR2, and HCDR3 of the VH2 of SEQ ID NO: 16. In some embodiments, the second antigen-binding arm that binds GPRC5D comprises LCDR1, LCDR2, and LCDR3 of the VL2 of SEQ ID NO: 15. In some embodiments, the second antigen-binding arm that binds GPRC5D comprises: HCDR1 comprising the amino acid sequence of GFSLTNIRMSVS (SEQ ID NO: 12), HCDR2 comprising the amino acid sequence of HIFSNDEKS (SEQ ID NO: 13) , and HCDR3 comprising the amino acid sequence of MRLPYGMDV (SEQ ID NO: 14). In some embodiments, the second antigen-binding arm that binds GPRC5D comprises: LCDR1 comprising the amino acid sequence of RSSQSLVHSDGNTYLS (SEQ ID NO: 9), LCDR2 comprising the amino acid sequence of KISNRFF (SEQ ID NO: 10) , and LCDR3 comprising the amino acid sequence of MQATQFPHT (SEQ ID NO: 11). In some embodiments, the second antigen binding arm that binds GPRC5D comprises the VH1 of SEQ ID NO: 16. In some embodiments, the second antigen binding arm that binds GPRC5D comprises VL1 of SEQ ID NO: 15.

[0087] In some embodiments, the third antigen binding arm that binds BCMA comprises HCDR1, HCDR2, and HCDR3 of the VH3 of SEQ ID NO: 24. In some embodiments, the third antigen-binding arm that binds BCMA comprises LCDR1, LCDR2, and LCDR3 of VL3 of SEQ ID NO: 23. In some embodiments, the third antigen-binding arm that binds BCMA comprises: HCDR1 comprising the amino acid sequence of GFTFSSYAMS (SEQ ID NO: 20), HCDR2 comprising the amino acid sequence of AISGSGGSTY (SEQ ID NO: 21) , and HCDR3 comprising the amino acid sequence of DEGYSSGHYYGMDV (SEQ ID NO: 22); and LCDR1 comprising the amino acid sequence of RASQSISSSFLT (SEQ ID NO: 17). In some embodiments, the third antigen-binding arm that binds BCMA comprises: LCDR2 comprising the amino acid sequence of GASSRAT (SEQ ID NO: 18), and comprising an amino acid sequence of QHYGSSPMYT (SEQ ID NO: 19) LCDR3. In some embodiments, the third antigen-binding arm that binds BCMA comprises the VH1 of SEQ ID NO: 24. In some embodiments, the third antigen binding arm that binds BCMA comprises VL1 of SEQ ID NO: 23.

[0088] In some embodiments, the VH1 and VL1 that bind to the antigen-binding arm of the CD3 epitope are present in a diabody, Fab, Fab', F(ab')2, Fv, scFv, Fd, disulfide bond Stable Fv fragments (dsFv), or disulfide bond-stabilized diabodies (ds diabodies).

[0089] In some embodiments, the VH2 and VL2 that bind to the antigen-binding arm of the GPRC5D epitope are present in a diabody, Fab, Fab', F(ab')2, Fv, scFv, Fd, disulfide bond Stable Fv fragments (dsFv), or disulfide bond-stabilized diabodies (ds diabodies).

[0090] In some embodiments, the VH3 and VL3 that bind to the antigen binding arm of the BCMA epitope are present in a diabody, Fab, Fab', F(ab')2, Fv, scFv, Fd, disulfide bond Stable Fv fragments (dsFv), or disulfide bond-stabilized diabodies (ds diabodies).

[0091] In some embodiments, the first antigen-binding arm of the BCMA x GPRC5D x CD3 multispecific antibody comprises: a first heavy chain portion (HC1) comprising the VH1 and a light chain portion (LC) comprising the VL1 , wherein the VH1 and VL1 pair form a first antigen binding domain that binds a first antigen. In some embodiments, the HC1 comprises the VH1, the first heavy chain constant domain (CH1), and the first Fc domain from N to C-terminus. In some embodiments, the VH1 and CH1 of the HC1 together with the LC form a fragment antigen binding (Fab) domain.

[0092] In some embodiments, the VH1 of the first antigen-binding arm is coupled to the VH3 of the third antigen-binding arm via the first Fc domain. In some embodiments, the first Fc domain of the first antigen-binding arm is coupled to the third antigen-binding arm via a first linker (L1), thereby forming coupled first and third antigen-binding arms. The coupled first and third antigen-binding arms may comprise the VH1, the CH1 domain, and the Fc domain of the first antigen-binding arm, the first linker, and the third antigen-binding arm from N to C-terminal arm. In some embodiments, the third antigen binding arm is a single chain variable fragment (scFv) formed from the VH3 and VL3 of the third antigen binding arm.

[0093] In some embodiments, the second antigen binding arm of the BCMA x GPRC5D x CD3 multispecific antibody comprises a second heavy chain portion (HC2) comprising a second heavy chain portion that forms a second antigen binding The second heavy chain variable domain (VH2) of the second antigen binding domain. In some embodiments, the second binding arm comprises a single-chain variable fragment (scFv) formed by the VH2 and VL2, and a second Fc domain from the N-terminus to the C-terminus.

[0094] In some embodiments, the VH2 of the second antigen binding arm is coupled to the VH3 of the third antigen binding arm via the second Fc domain. In some embodiments, the second Fc domain of the second antigen binding arm is coupled to the third antigen binding arm via a linker, thereby forming coupled second and third antigen binding arms. The coupled second and third antigen binding arms may comprise the second antigen binding domain, the second Fc domain, the first linker, and the third antigen binding arm from N to C terminus. In some embodiments, the third antigen binding arm is a single chain variable fragment (scFv) formed from the VH3 and VL3 of the third antigen binding arm.

[0095] In a preferred embodiment, the BCMA x GPRC5D x CD3 multispecific antibody system comprises a trispecific antibody of the CD3 specific arm, and the CD3 specific arm comprises: comprising the first heavy chain portion of the VH1 (HC1 ) and the light chain portion (LC) comprising the VL1. This pair of VH1 and VL1 domains forms the first antigen-binding domain that binds CD3. The second antigen binding arm of the trispecific antibody comprises a second heavy chain portion (HC2) with the VH2 forming the second antigen binding domain that binds the second antigen. HC1 of the CD3-specific binding arm or HC2 of the second antigen-binding arm is coupled to the third antigen-binding arm comprising the VH3 domain, which forms the third antigen-binding domain that binds the third antigen. In some embodiments, the second antigen is BCMA and the third antigen is GPRC5D. In some embodiments, the second antigen is GPRC5D and the third antigen is BCMA.

[0096] In one embodiment, the BCMA x GPRC5D x CD3 multispecific antibody system comprises a trispecific antibody with a CD3-specific binding arm, and the CD3-specific binding arm comprises HC1 with the VH1 and LC with the VL1 . The VH1 and VL1 pair form the first CD3-specific antigen binding domain that binds CD3. The second antigen binding arm comprises the VH2 and VL2 forming the second antigen binding domain that binds GPRC5D. The third antigen binding arm is coupled to the second antigen binding arm and comprises the VH3 and VL3 forming the third antigen binding domain that binds BCMA.

[0097] In one embodiment, the BCMA x GPRC5D x CD3 multispecific antibody system comprises a trispecific antibody with a CD3-specific binding arm, and the CD3-specific binding arm comprises HC1 with the VH1 and LC with the VL1 . The VH1 and VL1 pair form the first CD3-specific antigen binding domain that binds CD3. The second antigen binding arm comprises the VH2 and VL2 forming the second antigen binding domain that binds BCMA. The third antigen binding arm is coupled to the second antigen binding arm and comprises the VH3 and VL3 forming the third antigen binding domain that binds GPRC5D.

[0098] In one embodiment, the BCMA x GPRC5D x CD3 multispecific antibody system comprises a trispecific antibody with a CD3-specific binding arm, and the CD3-specific binding arm comprises HC1 with the VH1 and LC with the VL1 . The VH1 and VL1 pair form the first CD3-specific antigen binding domain that binds CD3. The second antigen binding arm comprises the VH2 and VL2 forming the second antigen binding domain that binds GPRC5D. The third antigen binding arm is coupled to the first CD3-specific antigen binding arm and comprises the VH3 and VL3 forming the third antigen binding domain that binds BCMA.

[0099] In one embodiment, the BCMA x GPRC5D x CD3 multispecific antibody system comprises a trispecific antibody with a CD3-specific binding arm, and the CD3-specific binding arm comprises HC1 with the VH1 and LC with the VL1 . The VH1 and VL1 pair form the first CD3-specific antigen binding domain that binds CD3. The second antigen binding arm comprises the VH2 and VL2 forming the second antigen binding domain that binds BCMA. The third antigen binding arm is coupled to the first CD3-specific antigen binding arm and comprises the VH3 and VL3 forming the third antigen binding domain that binds GPRC5D.

[0100] In some embodiments, the HC1 with the VH1 and LC domain with the VL1 of the first antigen-binding arm form an antigen-binding fragment (Fab) comprising the first antigen-binding domain. In some embodiments, the VH2 and VL2 of the second antigen binding arm form a single chain variable fragment (scFv) comprising the second antigen binding domain. In some embodiments, the VH3 and VL3 of the third antigen binding arm form a single chain variable fragment (scFv) comprising the third antigen binding domain.

[0101] In one embodiment, the CD3 binding arm comprises an antigen binding fragment (Fab), the BCMA binding arm comprises a single chain variable fragment (scFv), and the GPRC5D binding arm comprises a single chain variable fragment (scFv).

[0102] In one embodiment, the CD3 binding arm comprises a single chain variable fragment (scFv), the BCMA binding arm comprises an antigen binding fragment (Fab), and the GPRC5D binding arm comprises a single chain variable fragment (scFv).

[0103] In one embodiment, the CD3 binding arm comprises a single chain variable fragment (scFv), the BCMA binding arm comprises a single chain variable fragment (scFv), and the GPRC5D binding arm comprises an antigen binding fragment (Fab).

[0104] In some embodiments, the CD3 binding arm of the trispecific antibody comprises the HC1 and the LC. The HC1 may comprise constant heavy chain regions (CH1, CH2, and CH3) and the VH1. The LC can comprise the VL1. The VH1 and VL1 combine to form the CD3 antigen binding domain.

[0105] In some embodiments, the GPRC5D binding arm of the trispecific antibody comprises the HC2. The HC2 may comprise constant heavy chain regions (CH2 and CH3), and a single chain variable fragment (scFv) attached to the N-terminus of the CH2 region, wherein the scFv comprises the GPRC5D antigen-binding domain.

[0106] In some embodiments, the trispecific antibody further comprises a BCMA antigen binding arm attached to the C-terminus of the CH3 region of the GPRC5D binding arm to form a GPRC5D / BCMA binding arm. In some embodiments, the BCMA binding arm comprises a second single-chain variable fragment (scFv). In some embodiments, the GPRC5D / BCMA arm may have the following structure: scFv containing the GPRC5D binding domain, CH2 and CH3 regions, scFv containing the BCMA binding domain.

[0107] In some embodiments, the CD3 binding arm of the trispecific antibody comprises the HC1 and the LC. The HC1 may comprise constant heavy chain regions (CH1, CH2, and CH3) and the VH1. The LC can comprise the VL1. The VH1 and VL1 combine to form the CD3 antigen binding domain.

[0108] In some embodiments, the BCMA-binding arm of the trispecific antibody comprises HC2. The HC2 may comprise constant heavy chain regions (CH2 and CH3), and a single chain variable fragment (scFv) attached to the N-terminus of the CH2 region, wherein the scFv comprises the BCMA antigen-binding domain.

[0109] In some embodiments, the trispecific antibody further comprises a GPRC5D antigen binding arm attached to the C-terminus of the CH3 region of the CD3 binding arm to form a CD3 / GPRC5D binding arm. In some embodiments, the BCMA binding arm comprises a second single-chain variable fragment (scFv). In some embodiments, the CD3 / GPRC5D arm can have the following structure: Fab containing the CD3 binding domain, CH2, and CH3 regions, scFv containing the GPRC5D binding domain.

[0110] In some embodiments, multispecific antibodies of the invention include antibodies having the structure of a full-length antibody. A "full length antibody" as used herein refers to an antibody having two full length antibody heavy chains and two full length antibody light chains. A full-length antibody heavy chain (HC) includes heavy chain variable domains and constant domains VH, CH1, CH2, and CH3. A full-length antibody light chain (LC) includes light chain variable domains and constant domains VL and CL. Full-length antibodies may lack a C-terminal lysine (K) in either or both heavy chains. The term "Fab-arm" or "half molecule" refers to a heavy chain-light chain pair that binds an antigen. In some embodiments, one of the antigen binding domains is a non-antibody-based binding domain, such as a fibronectin type 3 domain-based binding domain, such as Centyrin. BCMA binding arm

[0111] The BCMA x GPRC5D x CD3 multispecific antibodies described herein comprise an antigen binding arm directed against BCMA. In some embodiments, the BCMA binding arm binds human BCMA. In some embodiments, the BCMA binding arm binds human BCMA and cynomolgus BCMA. In some embodiments, the BCMA binding arm binds human BCMA but does not bind cynomolgus monkey BCMA. In some embodiments, the BCMA binding arm binds to an epitope comprising one or more residues from the BCMA extracellular domain (ECD). In some embodiments, the BCMA binding arm binds to residues 17 to 26 of the BCMA BCMW37 chain (LLHACIPCQL (SEQ ID NO: 162)).

[0112] The BCMA binding arms may be 5 x 10-7 M or lower (such as 1 x 10-7 M or lower, 5 x 10-8 M or lower, 1 x 10-8 M or lower, 5 x 10-9 M or lower, 1 x10-9M or less, or 5 x10-10M or less) to BCMA. In one embodiment, the BCMA binding arm binds to the BCMA with an affinity of about 1 x 10-10M to 1 x 10-7M. In one embodiment, the BCMA binding arm is at about 1 x 10-10M, about 2 x 10-10M, about 3 x 10-10M, about 4 x 10-10M, about 5 x 10-10M, about 6 x 10-10M, about 7 x 10 -10M, about 8 x10-10M, about 9x10-10M, about 1x10-9M, about 2 x10-9M, about 3 x10-9M, about 4 x10-9M, about 5 x10-9M, about 6 x10-9M, about Binds to the BCMA with an affinity of 7x10-9M, about 8x10-9M, or about 9x10-9M. In one embodiment, the BCMA binding arm is at about 1 x10-10 to 5 x10-10M, about 1 x10-10 to 8 x10-10M, about 2 x10-10 to 9 x10-10M, about 3 x10-10 to Binds to the BCMA with an affinity of 10x10-10M, about 4x10-10 to 10x10-10M, or about 5x10-10 to 10x10-10M. In one embodiment, the BCMA binding arm binds to the BCMA with an affinity of about 8.4 x 10-10 M as determined by a surface plasmon resonance (SPR) assay. In one embodiment, the BCMA binding arm binds to the BCMA with an affinity of about 2.1 x 10-10 M as determined by a surface plasmon resonance (SPR) assay.

[0113] Table 1 provides a summary of examples of some of the BCMA-specific antibodies described herein: Table 1. CDR sequences of exemplary mAbs raised against human BCMA ID HC-CDR1 HC-CDR2 HC-CDR3 LC-CDR1 LC-CDR2 LC-CDR3 BCMB519 GFTFSSYAMS (SEQ ID NO 20) AISGSGGSTY (SEQ ID NO 21) DEGYSSGHYYGMDV (SEQ ID NO 22) RASQSISSSFLT (SEQ ID NO 17) GASSRAT (SEQ ID NO 18) QHYGSSPMYT (SEQ ID NO 19) BCMB69 SGSYFWG (SEQ ID NO 32) SIYYSGITYYNPSLKS (SEQ ID NO 33) HDGAVAGLFDY (SEQ ID NO 34) GGNNIGSKSVH (SEQ ID NO 39) DDSDRPS (SEQ ID NO 40) QVWDSSSDHVV (SEQ ID NO 41) BCMB117 SGSYFWG (SEQ ID NO 32) SIYYSGITYYNPSLKS (SEQ ID NO 33) HDGAVAGLFDY (SEQ ID NO 34) GGNNIGSKSVH (SEQ ID NO 39) DDSDRPS (SEQ ID NO 40) QVWDSSSDHVV (SEQ ID NO 41) BCMB123 SSSYFWG (SEQ ID NO 38) SIYYSGITYYNPSLKS (SEQ ID NO 33) HDGAVAGLFDY (SEQ ID NO 34) GGNNIGSKSVH (SEQ ID NO 39) DDSDRPS (SEQ ID NO 40) QVWDSSSDHVV (SEQ ID NO 41) BCMB128 SGSYFWG (SEQ ID NO 32) SIYYSGITYYNPSLKS (SEQ ID NO 33) HDGATAGLFDY (SEQ ID NO 37) GGNNIGSKSVH (SEQ ID NO 39) DDSDRPS (SEQ ID NO 40) QVWDSSSDHVV (SEQ ID NO 41) BCMB129 SGSYFWG (SEQ ID NO 32) SIYYSGSTYYNPSLKS (SEQ ID NO 36) HDGAVAGLFDY (SEQ ID NO 34) GGNNIGSKSVH (SEQ ID NO 39) DDSDRPS (SEQ ID NO 40) QVWDSSSDHVV (SEQ ID NO 41) BCMB176 SSSYFWG (SEQ ID NO 38) SIYYSGITYYNPSLKS (SEQ ID NO 33) HDGATAGLFDY (SEQ ID NO 37) GGNNIGSKSVH (SEQ ID NO 39) DDSDRPS (SEQ ID NO 40) QVWDSSSDHVV (SEQ ID NO 41) BCMB177 SSSYFWG (SEQ ID NO 38) SIYYSGRTYYNPSLKS (SEQ ID NO 164) HDGATAGLFDY (SEQ ID NO 37) GGNNIGSKSVH (SEQ ID NO 39) DDSDRPS (SEQ ID NO 40) QVWDSSSDHVV (SEQ ID NO 41)

[0114] Some BCMA-specific antibodies or antigen-binding fragments can be characterized, for example, in US Patent No. 10,072,088, the contents of which are incorporated herein by reference in their entirety.

[0115] In some embodiments, the BCMA binding arm comprises a heavy chain variable domain comprising the heavy chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 1. In some embodiments, the BCMA binding arm comprises a light chain variable region comprising light chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 1. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain comprising heavy chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 1 and a light chain variable region , the light chain variable region comprising any one of the light chain CDR1, CDR2, and CDR3 of the antibody described in Table 1. In some embodiments, the BCMA binding arm competes for binding to BCMA with an antibody or antigen binding comprising a heavy chain comprising a heavy chain CDR1, CDR2, and CDR3, the light chain comprising the light chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 1.

[0116] In some embodiments, the BCMA binding arm comprises a heavy chain comprising the heavy chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 1. In some embodiments, the BCMA-binding arm comprises a light chain comprising light chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 1. In some embodiments, the BCMA binding arm comprises a heavy chain comprising the heavy chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 1, and a light chain comprising the heavy chains described in Table 1. Light chain CDR1, CDR2, and CDR3 of any of the antibodies described above.

[0117] In some embodiments, the BCMA-binding arm comprises heavy chain CDR1, CDR2, and CDR3 of the following clones: BCMB519, BCMB69, BCMB117, BCMB123, BCMB128, BCMB129, BCMB176, or BCMB177. In some embodiments, the BCMA-binding arm comprises heavy chain CDR1, CDR2, and CDR3 and light chain CDR1, CDR2, and CDR3 of the following strains: BCMB519, BCMB69, BCMB117, BCMB123, BCMB128, BCMB129, BCMB176, or BCMB177. In one embodiment, the BCMA binding arm comprises heavy chain CDR1, CDR2, and CDR3 and light chain CDR1, CDR2, and CDR3 of clone BCMB519.

[0118] In some embodiments, the BCMA binding arm comprises a heavy chain variable domain derived from an antibody plant as described in Table 1. In some exemplary embodiments, the BCMA-binding arm comprises a heavy chain variable domain and a light chain variable domain derived from an antibody plant as described in Table 1. In some exemplary embodiments, the BCMA-binding arm comprises a heavy chain variable domain and a light chain variable domain from strains BCMB519, BCMB69, BCMB117, BCMB123, BCMB128, BCMB129, BCMB176, or BCMB177. In one embodiment, the BCMA binding arm comprises a heavy chain variable domain and a light chain variable domain of clone BCMB519.

[0119] In some embodiments, the BCMA binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 20, a heavy chain CDR2 comprising SEQ ID NO: 21, and a heavy chain CDR3 comprising SEQ ID NO: 22. In some embodiments, the BCMA binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 20, heavy chain CDR2 comprising SEQ ID NO: 21, heavy chain CDR3 comprising SEQ ID NO: 22, comprising SEQ ID NO: The light chain CDR1 of 17, the light chain CDR2 comprising SEQ ID NO: 18, and the light chain CDR3 comprising SEQ ID NO: 19. The BCMA binding arm can comprise human framework sequences. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 24. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 24 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 23.

[0120] In some embodiments, the BCMA binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 32, a heavy chain CDR2 comprising SEQ ID NO: 33, and a heavy chain CDR3 comprising SEQ ID NO: 34. In some embodiments, the BCMA binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 32, heavy chain CDR2 comprising SEQ ID NO: 33, heavy chain CDR3 comprising SEQ ID NO: 34, comprising SEQ ID NO: The light chain CDR1 of 39, the light chain CDR2 comprising SEQ ID NO: 40, and the light chain CDR3 comprising SEQ ID NO: 41. The BCMA binding arm can comprise human framework sequences. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 42. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 42 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 48.

[0121] In some embodiments, the BCMA binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 38, a heavy chain CDR2 comprising SEQ ID NO: 33, and a heavy chain CDR3 comprising SEQ ID NO: 34. In some embodiments, the BCMA binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 38, heavy chain CDR2 comprising SEQ ID NO: 33, heavy chain CDR3 comprising SEQ ID NO: 34, comprising SEQ ID NO: The light chain CDR1 of 39, the light chain CDR2 comprising SEQ ID NO: 40, and the light chain CDR3 comprising SEQ ID NO: 41. The BCMA binding arm can comprise human framework sequences. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 43. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 43 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 48.

[0122] In some embodiments, the BCMA binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 32, a heavy chain CDR2 comprising SEQ ID NO: 33, and a heavy chain CDR3 comprising SEQ ID NO: 37. In some embodiments, the BCMA binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 32, heavy chain CDR2 comprising SEQ ID NO: 33, heavy chain CDR3 comprising SEQ ID NO: 37, comprising SEQ ID NO: The light chain CDR1 of 39, the light chain CDR2 comprising SEQ ID NO: 40, and the light chain CDR3 comprising SEQ ID NO: 41. The BCMA binding arm can comprise human framework sequences. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 44. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 44 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 48.

[0123] In some embodiments, the BCMA binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 32, a heavy chain CDR2 comprising SEQ ID NO: 36, and a heavy chain CDR3 comprising SEQ ID NO: 34. In some embodiments, the BCMA binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 32, heavy chain CDR2 comprising SEQ ID NO: 36, heavy chain CDR3 comprising SEQ ID NO: 34, comprising SEQ ID NO: The light chain CDR1 of 39, the light chain CDR2 comprising SEQ ID NO: 40, and the light chain CDR3 comprising SEQ ID NO: 41. The BCMA binding arm contains human framework sequences. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 45. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 45 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 48.

[0124] In some embodiments, the BCMA binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 38, a heavy chain CDR2 comprising SEQ ID NO: 33, and a heavy chain CDR3 comprising SEQ ID NO: 37. In some embodiments, the BCMA binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 38, heavy chain CDR2 comprising SEQ ID NO: 33, heavy chain CDR3 comprising SEQ ID NO: 37, comprising SEQ ID NO: The light chain CDR1 of 39, the light chain CDR2 comprising SEQ ID NO: 40, and the light chain CDR3 comprising SEQ ID NO: 41. The BCMA binding arm can comprise human framework sequences. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 46. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 46 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 48.

[0125] In some embodiments, the BCMA binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 38, a heavy chain CDR2 comprising SEQ ID NO: 164, and a heavy chain CDR3 comprising SEQ ID NO: 37. In some embodiments, the BCMA binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 38, heavy chain CDR2 comprising SEQ ID NO: 164, heavy chain CDR3 comprising SEQ ID NO: 37, comprising SEQ ID NO: The light chain CDR1 of 39, the light chain CDR2 comprising SEQ ID NO: 40, and the light chain CDR3 comprising SEQ ID NO: 41. The BCMA binding arm can comprise human framework sequences. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 47. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 47 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 48.

[0126] The BCMA binding arm can be derived from any species by recombinant means. For example, the BCMA binding arm can be derived from chimeric versions of mouse, rat, goat, horse, pig, cow, chicken, rabbit, camel, donkey, human, or the like. For use in humans, non-human derived antigen-binding fragments may be genetically or structurally modified to be less antigenic when administered to a human patient. In some embodiments, the BCMA-binding arm comprises a chimeric antigen-binding fragment.

[0127] In some embodiments, the BCMA-binding arm comprises a humanized antigen-binding fragment. Humanized antigen-binding fragments may be derived from chimeric immunoglobulins, immunoglobulin chains or fragments thereof (such as Fv, Fab, Fab', F(ab')2 or antibody other antigen-binding subsequences). In most cases, humanized antibodies or antigen-binding fragments are human immunoglobulins (recipient antibodies) or antigen-binding fragments in which residues from the complementarity determining regions (CDRs) of the recipient are modified from Substitution of residues in CDRs of a non-human species (donor antibody) such as mouse, rat or rabbit with desired specificity, affinity, and capacity. In general, the antigen-binding fragment of a humanized antibody will comprise substantially all of at least one and typically two variable domains, wherein all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin, and all or substantially All framework regions are those of human immunoglobulin sequences. The antigen-binding fragment of a humanized antibody can comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. GPRC5D binding arm

[0128] The BCMAx GPRC5DxCD3 multispecific antibodies described herein comprise an antigen binding arm directed against GPRC5D. In some embodiments, the GPRC5D binding arm binds human GPRC5D. In some embodiments, the GPRC5D binding arm binds human GPRC5D and cynomolgus GPRC5D, preferably its extracellular domain. In some embodiments, the GPRC5D binding arm binds human GPRC5D but does not bind cynomolgus GPRC5D. In some embodiments, the GPRC5D binding arm binds to one or more residues of a polypeptide having the amino acid sequence of SEQ ID NO: 116.

[0129] Table 2 provides an example summary of some of the GPRC5D-specific antibodies described herein: Table 2. CDR sequences of exemplary mAbs raised against human GPRC5D ID HC-CDR1 HC-CDR2 HC-CDR3 LC-CDR1 LC-CDR2 LC-CDR3 GC5B680 GFSLTNIRMSVS (SEQ ID NO: 12) HIFSNDEKS (SEQ ID NO: 13) MRLPYGMDV (SEQ ID NO: 14) RSSQSLVHSDGNTYLS (SEQ ID NO:9) KISNRFF (SEQ ID NO: 10) MQATQFPHT (SEQ ID NO: 11) GC5B81 SYAIS (SEQ ID NO 49) GIIPIFGTANYAQKFQG (SEQ ID NO 53) ESRWRGYKLD (SEQ ID NO 57) RASQSISSYLN (SEQ ID NO 61) AASSLQS (SEQ ID NO 64) QQSYSTPLT (SEQ ID NO 67) GC5B465 GC5B597 GC5B598 NYWMS (SEQ ID NO 50) GISYSGGSKYYASSVKG (SEQ ID NO 54) AAFDFGRRAVRLD (SEQ ID NO 58) RASQSISSYLN (SEQ ID NO 61) AASSLQS (SEQ ID NO 64) QQSYSTPLT (SEQ ID NO 67) GC5B483 GC5B599 SYFIG (SEQ ID NO 51) IIYPGKSDTRYSPSFQG (SEQ ID NO 55) VYSFGGRHKALFDY (SEQ ID NO 59) RASQSVSSYLA (SEQ ID NO 62) DASNRAT (SEQ ID NO 65) QQRSNWPLT (SEQ ID NO 68) GC5B596 GYTMN (SEQ ID NO 52) LINPYNSDTNYAQKLQG (SEQ ID NO 56) VALRVALDY (SEQ ID NO 60) KASQNVATHVG (SEQ ID NO 63) SASYRYS (SEQ ID NO 66) QQYNRYPYT (SEQ ID NO 69) GC5B382 DYGMH (SEQ ID NO 70) AIKYSGGSTYYADSVKG (SEQ ID NO 77) RAESGPGLDY (SEQ ID NO 84) KSSQSVLYSSNNKNYLA (SEQ ID NO 91) WASTRES (SEQ ID NO 93) QQYYSTPLT (SEQ ID NO 95) GC5B379 NYWMS (SEQ ID NO 50) GISYSGGSKYYADSVKG (SEQ ID NO 78) AAWDFGRRAVRLDY (SEQ ID NO 85) RASQSISSYLN (SEQ ID NO 61) AASSLQS (SEQ ID NO 64) QQSYSTPLT (SEQ ID NO 67) GC5B373 SYWIG (SEQ ID NO 71) IIYPGDSDTRYSPSFQG (SEQ ID NO 79) IGFYGRSFRIFDY (SEQ ID NO 86) RASQSVSSYLA (SEQ ID NO 62) DASNRAT (SEQ ID NO 65) QQRSNWPLT (SEQ ID NO 68) GC5B376 SYWIG (SEQ ID NO 71) IIYPGDSDTRYSPSFQG (SEQ ID NO 79) VYSFGGRHKALFDY (SEQ ID NO 59) RASQSVSSYLA (SEQ ID NO 62) DASNRAT (SEQ ID NO 65) QQRSNWPLT (SEQ ID NO 68) GC5B385 GYAMS (SEQ ID NO 72) AISGSGGSTYYADSVKG (SEQ ID NO 80) VDRSFGRSRYTLDY (SEQ ID NO 87) RASQSVSSYLA (SEQ ID NO 62) DASNRAT (SEQ ID NO 65) QQRSNWPLT (SEQ ID NO 68) GC5B370 SYGIS (SEQ ID NO 73) GIIPIFGNINYAQKFQG (SEQ ID NO 81) VSRRFKRFAYYFDY (SEQ ID NO 88) KSSQSVLYSSNNKNYLA (SEQ ID NO 91) WASTRES (SEQ ID NO 93) QQYYSTPLT (SEQ ID NO 95) GC5B602 GYSFTGYTMN (SEQ ID NO 74) LINPYNG DTN (SEQ ID NO 82) VALRVALDY (SEQ ID NO 60) KASQNVATHVG (SEQ ID NO 63) SASYRYS (SEQ ID NO 66) QQYNRYPYT (SEQ ID NO 69) GC5B603 SYAMS (SEQ ID NO 75) AISGSGGSTYYADSVKG (SEQ ID NO 80) SNFLPVVFDY (SEQ ID NO 89) RASQSVRKSLA (SEQ ID NO 92) TASNRAT (SEQ ID NO 94) QQYFRAPIT (SEQ ID NO 96) GC5B601 GFSLTSYNVH (SEQ ID NO 76) VIWAGGSTNYNSALMS (SEQ ID NO 83) DGIRLRFAY (SEQ ID NO 90) KASQNVATHVG (SEQ ID NO 63) SASYRYS (SEQ ID NO 66) QQYNRYPYT (SEQ ID NO 69)

[0130] Some GPRC5D-specific antibodies or antigen-binding fragments can be characterized in, eg, US Patent No. 10,562,968, US Publication US2020 / 0231686, the contents of each of which are incorporated herein by reference in their entirety.

[0131] In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain comprising heavy chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 2. In some embodiments, the GPRC5D binding arm comprises a light chain variable domain comprising light chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 2. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain and a light chain variable domain, the heavy chain variable domain comprising heavy chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 2 , the light chain variable domain comprising any one of the light chain CDR1, CDR2, and CDR3 of the antibody described in Table 2. In some embodiments, the GPRC5D binding arm competes for binding to GPRC5D with an antibody or antigen binding comprising a heavy chain comprising a heavy chain CDR1, CDR2, and CDR3, the light chain comprising the light chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 2.

[0132] In some embodiments, the GPRC5D binding arm comprises a heavy chain comprising the heavy chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 2. In some embodiments, the GPRC5D binding arm comprises a light chain comprising light chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 2. In some embodiments, the GPRC5D binding arm comprises a heavy chain comprising the heavy chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 2, and a light chain comprising the heavy chains described in Table 2. Light chain CDR1, CDR2, and CDR3 of any of the antibodies described above.

[0133] In some embodiments, the GPRC5D binding arm comprises heavy chain CDR1, CDR2, and CDR3 derived from an antibody plant as described in Table 2. In some embodiments, the GPRC5D binding arm comprises light chain CDR1, CDR2, and CDR3 derived from the antibody plants as described in Table 2. In some embodiments, the GPRC5D binding arm comprises heavy chain CDR1, CDR2, and CDR3 and light chain CDR1, CDR2, and CDR3 derived from the antibody strains described in Table 2. In some embodiments, the GPRC5D binding arm comprises heavy chain CDR1, CDR2, and CDR3 of the following plants: GC5B680, GC5B81, GC5B465, GS5B483, GC5B596, GC5B382, GC5B379, GC5B373, GC5B376, GC5B385, GC5B370, GC5B602, GC5B603 , GC5B599 , GC5B601, GC5B598, or GC5B597. In some embodiments, the GPRC5D binding arm comprises heavy chain CDR1, CDR2, and CDR3 and light chain CDR1, CDR2, and CDR3 of the following plants: GC5B680, GC5B81, GC5B465, GS5B483, GC5B596, GC5B382, GC5B379, GC5B373, GC5B376, GC5B385, GC5B370, GC5B602, GC5B603, GC5B599, GC5B601, GC5B598, or GC5B597. In one embodiment, the GPRC5D binding arm comprises heavy chain CDR1, CDR2, and CDR3 and light chain CDR1, CDR2, and CDR3 of clone GC5B680.

[0134] In some exemplary embodiments, the GPRC5D binding arm comprises a heavy chain variable domain derived from an antibody plant as described in Table 2. In some exemplary embodiments, the GPRC5D binding arm comprises a heavy chain variable domain and a light chain variable domain derived from an antibody plant as described in Table 2. In some exemplary embodiments, the GPRC5D binding arm comprises the heavy chain variable domain and the light chain variable domain of the following plants: GC5B680, GC5B81, GC5B465, GS5B483, GC5B596, GC5B382, GC5B379, GC5B373, GC5B376, GC5B385, GC5B370, GC5B602, GC5B603, GC5B599, GC5B601, GC5B598, or GC5B597. In one embodiment, the GPRC5D binding arm comprises the heavy chain variable domain and the light chain variable domain of clone GC5B680. In some embodiments, the GPRC5D-specific antibody clone can induce ADCC in vitro with an EC50 of 28 nM or less.

[0135] In some embodiments, the GPRC5D binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 12, a heavy chain CDR2 comprising SEQ ID NO: 13, and a heavy chain CDR3 comprising SEQ ID NO: 14. In some embodiments, the GPRC5D binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 12, heavy chain CDR2 comprising SEQ ID NO: 13, heavy chain CDR3 comprising SEQ ID NO: 14, comprising SEQ ID NO: The light chain CDR1 of 9, the light chain CDR2 comprising SEQ ID NO: 10, and the light chain CDR3 comprising SEQ ID NO: 11. The GPRC5D binding arm can comprise human framework sequences. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 16. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 16 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 15.

[0136] In some embodiments, the GPRC5D binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 49, a heavy chain CDR2 comprising SEQ ID NO: 53, and a heavy chain CDR3 comprising SEQ ID NO: 57. In some embodiments, the GPRC5D binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 49, heavy chain CDR2 comprising SEQ ID NO: 53, heavy chain CDR3 comprising SEQ ID NO: 57, comprising SEQ ID NO: The light chain CDR1 of 61, the light chain CDR2 comprising SEQ ID NO: 64, and the light chain CDR3 comprising SEQ ID NO: 67. The GPRC5D binding arm can comprise human framework sequences. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 97. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 97 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 101.

[0137] In some embodiments, the GPRC5D binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 50, a heavy chain CDR2 comprising SEQ ID NO: 54, and a heavy chain CDR3 comprising SEQ ID NO: 58. In some embodiments, the GPRC5D binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 50, heavy chain CDR2 comprising SEQ ID NO: 54, heavy chain CDR3 comprising SEQ ID NO: 58, comprising SEQ ID NO: The light chain CDR1 of 61, the light chain CDR2 comprising SEQ ID NO: 64, and the light chain CDR3 comprising SEQ ID NO: 67. The GPRC5D binding arm can comprise human framework sequences. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 98. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 98 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 101.

[0138] In some embodiments, the GPRC5D binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 51, a heavy chain CDR2 comprising SEQ ID NO: 55, and a heavy chain CDR3 comprising SEQ ID NO: 59. In some embodiments, the GPRC5D binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 51, heavy chain CDR2 comprising SEQ ID NO: 55, heavy chain CDR3 comprising SEQ ID NO: 59, comprising SEQ ID NO: 62 light chain CDR1, light chain CDR2 comprising SEQ ID NO: 65, and light chain CDR3 comprising SEQ ID NO: 68. The GPRC5D binding arm can comprise human framework sequences. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 99. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 99 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 102.

[0139] In some embodiments, the GPRC5D binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 52, a heavy chain CDR2 comprising SEQ ID NO: 56, and a heavy chain CDR3 comprising SEQ ID NO: 60. In some embodiments, the GPRC5D binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 52, heavy chain CDR2 comprising SEQ ID NO: 56, heavy chain CDR3 comprising SEQ ID NO: 60, comprising SEQ ID NO: 63 light chain CDR1, light chain CDR2 comprising SEQ ID NO: 66, and light chain CDR3 comprising SEQ ID NO: 69. The GPRC5D binding arm can comprise human framework sequences. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 100. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 100 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 103.

[0140] In some embodiments, the GPRC5D binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 70, a heavy chain CDR2 comprising SEQ ID NO: 77, and a heavy chain CDR3 comprising SEQ ID NO: 84. In some embodiments, the GPRC5D binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 70, heavy chain CDR2 comprising SEQ ID NO: 77, heavy chain CDR3 comprising SEQ ID NO: 84, comprising SEQ ID NO: The light chain CDR1 of 91, the light chain CDR2 comprising SEQ ID NO: 93, and the light chain CDR3 comprising SEQ ID NO: 95. The GPRC5D binding arm can comprise human framework sequences. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 104. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 104 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 113.

[0141] In some embodiments, the GPRC5D binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 50, a heavy chain CDR2 comprising SEQ ID NO: 78, and a heavy chain CDR3 comprising SEQ ID NO: 85. In some embodiments, the GPRC5D binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 50, heavy chain CDR2 comprising SEQ ID NO: 78, heavy chain CDR3 comprising SEQ ID NO: 85, comprising SEQ ID NO: The light chain CDR1 of 61, the light chain CDR2 comprising SEQ ID NO: 64, and the light chain CDR3 comprising SEQ ID NO: 67. The GPRC5D binding arm can comprise human framework sequences. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 105. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 105 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 101.

[0142] In some embodiments, the GPRC5D binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO:71, a heavy chain CDR2 comprising SEQ ID NO:79, and a heavy chain CDR3 comprising SEQ ID NO:86. In some embodiments, the GPRC5D binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 71, heavy chain CDR2 comprising SEQ ID NO: 79, heavy chain CDR3 comprising SEQ ID NO: 86, comprising SEQ ID NO: 62 light chain CDR1, light chain CDR2 comprising SEQ ID NO: 65, and light chain CDR3 comprising SEQ ID NO: 68. The GPRC5D binding arm can comprise human framework sequences. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 106. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 106 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 102.

[0143] In some embodiments, the GPRC5D binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 71, a heavy chain CDR2 comprising SEQ ID NO: 79, and a heavy chain CDR3 comprising SEQ ID NO: 59. In some embodiments, the GPRC5D binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 71, heavy chain CDR2 comprising SEQ ID NO: 79, heavy chain CDR3 comprising SEQ ID NO: 59, comprising SEQ ID NO: 62 light chain CDR1, light chain CDR2 comprising SEQ ID NO: 65, and light chain CDR3 comprising SEQ ID NO: 68. The GPRC5D binding arm can comprise human framework sequences. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 107. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 107 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 102.

[0144] In some embodiments, the GPRC5D binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 72, a heavy chain CDR2 comprising SEQ ID NO: 80, and a heavy chain CDR3 comprising SEQ ID NO: 87. In some embodiments, the GPRC5D binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 72, heavy chain CDR2 comprising SEQ ID NO: 80, heavy chain CDR3 comprising SEQ ID NO: 87, comprising SEQ ID NO: 62 light chain CDR1, light chain CDR2 comprising SEQ ID NO: 65, and light chain CDR3 comprising SEQ ID NO: 68. The GPRC5D binding arm can comprise human framework sequences. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 108. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 108 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 102.

[0145] In some embodiments, the GPRC5D binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 73, a heavy chain CDR2 comprising SEQ ID NO: 81, and a heavy chain CDR3 comprising SEQ ID NO: 88. In some embodiments, the GPRC5D binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 73, heavy chain CDR2 comprising SEQ ID NO: 81, heavy chain CDR3 comprising SEQ ID NO: 88, comprising SEQ ID NO: The light chain CDR1 of 91, the light chain CDR2 comprising SEQ ID NO: 93, and the light chain CDR3 comprising SEQ ID NO: 95. The GPRC5D binding arm can comprise human framework sequences. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 109. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 109 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 113.

[0146] In some embodiments, the GPRC5D binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 74, a heavy chain CDR2 comprising SEQ ID NO: 82, and a heavy chain CDR3 comprising SEQ ID NO: 60. In some embodiments, the GPRC5D binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 74, heavy chain CDR2 comprising SEQ ID NO: 82, heavy chain CDR3 comprising SEQ ID NO: 60, comprising SEQ ID NO: 63 light chain CDR1, light chain CDR2 comprising SEQ ID NO: 66, and light chain CDR3 comprising SEQ ID NO: 69. The GPRC5D binding arm can comprise human framework sequences. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 110. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 110 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 103.

[0147] In some embodiments, the GPRC5D binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 75, a heavy chain CDR2 comprising SEQ ID NO: 80, and a heavy chain CDR3 comprising SEQ ID NO: 89. In some embodiments, the GPRC5D binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 75, heavy chain CDR2 comprising SEQ ID NO: 80, heavy chain CDR3 comprising SEQ ID NO: 89, comprising SEQ ID NO: The light chain CDR1 of 92, the light chain CDR2 comprising SEQ ID NO: 94, and the light chain CDR3 comprising SEQ ID NO: 96. The GPRC5D binding arm can comprise human framework sequences. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 111. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 111 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 114.

[0148] In some embodiments, the GPRC5D binding arm comprises: a heavy chain CDR1 comprising SEQ ID NO: 76, a heavy chain CDR2 comprising SEQ ID NO: 83, and a heavy chain CDR3 comprising SEQ ID NO: 90. In some embodiments, the GPRC5D binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 76, heavy chain CDR2 comprising SEQ ID NO: 83, heavy chain CDR3 comprising SEQ ID NO: 90, comprising SEQ ID NO: 63 light chain CDR1, light chain CDR2 comprising SEQ ID NO: 66, and light chain CDR3 comprising SEQ ID NO: 69. The GPRC5D binding arm can comprise human framework sequences. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 112. In some embodiments, the GPRC5D binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 112 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 115.

[0149] The GPRC5D binding arm can be derived from any species by recombinant means. For example, the GPRC5D antigen binding arm can be derived from a chimeric version of mouse, rat, goat, horse, pig, cow, chicken, rabbit, camel, donkey, human, or the like. For use in humans, non-human derived antigen-binding fragments may be genetically or structurally modified to be less antigenic when administered to a human patient. In some embodiments, the GPRC5D binding arm comprises a chimeric antigen-binding fragment.

[0150] In some embodiments, the GPRC5D binding arm comprises a humanized antigen-binding fragment. Humanized antigen-binding fragments may be derived from chimeric immunoglobulins, immunoglobulin chains or fragments thereof (such as Fv, Fab, Fab', F(ab')2 or antibody other antigen-binding subsequences). In most cases, humanized antibodies or antigen-binding fragments are human immunoglobulins (recipient antibodies) or antigen-binding fragments in which residues from the complementarity determining regions (CDRs) of the recipient are modified from Substitution of residues in CDRs of a non-human species (donor antibody) such as mouse, rat or rabbit with desired specificity, affinity, and capacity. In general, the antigen-binding fragment of a humanized antibody will comprise substantially all of at least one and typically two variable domains, wherein all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin, and all or substantially All framework regions are those of human immunoglobulin sequences. The antigen-binding fragment of a humanized antibody can comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. CD3 binding arm

[0151] The BCMA x GPRC5D x CD3 multispecific antibodies described herein comprise an antigen binding arm that binds CD3. In some embodiments, the CD3 binding arm binds human CD3. In some preferred embodiments, the CD3-specific arm of the BCMA x GPRC5D x CD3 multispecific antibody is derived from a CD3-specific antibody that binds and activates human primary T cells and / or cynomolgus monkey primary T cells. In some embodiments, the CD3 binding arm binds an epitope at the N-terminus of CD3ε. In some embodiments, the CD3 binding arm binds to residues 22 to 35 of the CD3 epsilon chain (QDGNEEMGGITQTP (SEQ ID NO: 161 )).

[0152] The CD3 binding arm may be 5 x 10-7M or lower (such as 1 x 10-7M or lower, 5 x 10-8M or lower, 1 x 10-8M or lower, 5 x 10-9M or lower, or 1 x10-9M or lower) binding affinity to CD3. In some embodiments, the CD3 binding arm is at about 1 x10-8M, about 2 x10-8M, about 3 x10-8M, about 4 x10-8M, about 5 x10-8M, about 6 x10-8M, about 7 x10 Binds to the CD3 with an affinity of -8M, about 8x10-8M, about 9x10-8M, or about 1x10-8M. In some embodiments, the CD3 binding arm is at about 1 x10-8M to about 3 x10-8M, about 2 x10-8M to about 4 x10-8M, about 1 x10-8M to about 5 x10-8M, about 2 x10 Binds to the CD3 with an affinity of -8M to about 6x10-8M, or about 3x10-8M to about 8x10-8M. In one embodiment, the CD3 binding arm binds to the CD3 with an affinity of about 2.5 x 10-8M. In one embodiment, the CD3 binding arm binds to the CD3 with an affinity of about 3.1 x 10-8M. In some embodiments, the CD3 binding affinity is determined by a surface plasmon resonance (SPR) assay.

[0153] The human CD3ε line is described in UniProt P07766 (CD3E_HUMAN). An anti-CD3ε antibody SP34 described in the state of the art (Yang SJ, The Journal of Immunology (1986) 137; 1097-1100). SP34 reacts with primate CD3 and human CD3. SP34 is commercially available from Pharmingen. A further anti-CD3 antibody is UCHT-1 as described in the state of the art (see WO2000041474). A further anti-CD3 antibody described in the state of the art is BC-3 (Fred Hutchinson Cancer Research Institute; Phase I / II trial for GvHD, Anasetti et al., Transplantation 54: 844 (1992)). The difference between SP34 and UCHT-1 and BC-3 is that SP-34 recognizes an epitope that exists only on the ε chain of CD3 (see Salmeron et al., (1991) J. Immunol. 147: 3047), while UCHT -1 and BC-3 recognize epitopes formed by both ε and γ chains. The sequences of antibodies having the same sequence as antibody SP34 are mentioned in WO2008119565, WO2008119566, WO2008119567, WO2010037836, WO2010037837, and WO2010037838. A sequence with 96% identity to the VH of antibody SP34 is mentioned in US8236308 (WO2007042261).

[0154] In some embodiments, the CD3 binding arm contacts an epitope comprising the six N-terminal amino acids of CD3ε. In some embodiments, the CD3-specific binding arm of the multispecific antibody is derived from mouse monoclonal antibody SP34, which is of the mouse IgG3 / λ isotype. In some embodiments, the CD3 binding arm comprises the CDRs of antibody SP34. Such CD3 binding arms may be 5 x 10-7 M or lower (such as 1 x 10-7 M or lower, 5 x 10-8 M or lower, 1 x 10-8 M or lower, 5 x 10-9 M or lower, or 1 x 10 -9M or lower) binding affinity to CD3. The CD3-specific binding arm can be a humanized version of the arm of the mouse monoclonal antibody SP34. Human framework adaptation (HFA) can be used to humanize the anti-CD3 antibody from which the CD3-specific arm is derived.

[0155] Table 3 provides a summary of examples of some of the CD3-specific antibodies described herein: Table 3. Heavy and light chains of exemplary CD3-specific antibodies and antigen-binding fragments heavy chain light chain CD3B376 CDR 1: GDSVFNNNAAWS (SEQ ID NO: 4) CDR 1: TGTSSNIGTYKFVS (SEQ ID NO: 1) CDR 2: RTYYRSKWLYD (SEQ ID NO: 5) CDR 2: EVSKRPS (SEQ ID NO: 2) CDR 3: GYSSSFDY (SEQ ID NO: 6) CDR 3: VSYAGSGTLL (SEQ ID NO: 3) VH: QVQLQQSGPRLVRPSQTLSLTCAISGDSVFNNNAAWSWIRQSPSRGLEWLGRTYYRSKWLYDYAVSVKSRITVNPDTSRNQFTLQLNSVTPEDTALYYCARGYSSSFDYWGQGTLVTVSS (SEQ ID NO: 8) VL: QSALTQPASVSGSPGQSITISCTGTSSNIGTYKFVSWYQQHPDKAPKVLLYEVSKRPSGVSSRFSGSKSGNTASLTISGLQAEDQADYHCVSYAGSGTLLFGGGTKLTVL (SEQ ID NO: 7) Heavy chain: QVQLQQSGPRLVRPSQTLSLTCAISGDSVFNNNAAWSWIRQSPSRGLEWLGRTYYRSKWLYDYAVSVKSRITVNPDTSRNQFTLQLNSVTPEDTALYYCARGYSSSFDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLY SLSSVVTVPSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPEAAGGPSVFLFPPKPKDTLMISRTPEVTCVVVSVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTK NQVSLSCAVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVSKLTVDKSRWQQGNVFSCSVMHEALHNRFTQKSLSLSPGK (SEQ ID NO: 26) Light chain: QSALTQPASVSGSPGQSITISCTGTSSNIGTYKFVSWYQQHPDKAPKVLLYEVSKRPSGVSSRFSGSKSGNTASLTISGLQAEDQADYHCVSYAGSGTLLFGGGTKLTVLGQPKAAPSVTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPSKQSNNKYAASSYLSLTPEQWKSH RSYSCQVTHEGSTVEKTVAPTECS (SEQ ID NO: 27) CD3B219 CDR 1: TYAMN (SEQ ID NO: 117) CDR 1: RSSTGAVTTSNYAN (SEQ ID NO: 122) CDR 2: RIRSKYNNYATYYAASVKG (SEQ ID NO: 118) CDR 2: GTNKRAP (SEQ ID NO: 123) CDR 3: HGNFGNSYVSWFAY (SEQ ID NO: 119) CDR 3: ALWYSNLWV (SEQ ID NO: 124) VH: EVQLVESGGGLVQPGGSLRLSCAASGFTFNTYAMNWVRQAPGKGLEWVARIRSKYNNYATYYAASVKGRFTISRDDSKNSLYLQMNSLKTEDTAVYYCARHGNFGNSYVSWFAYWGQGTLVTVSS (SEQ ID NO: 120) VL: QTVVTQEPSLTVSPGGTVTLTCRSSTGAVTTSNYANWVQQKPGQAPRGLIGGTNKRAPGTPARFSGSLLGGKAALTLSGVQPEDEAEYYCALWYSNLWVFGGGTKLTVL (SEQ ID NO: 125) Heavy chain: EVQLVESGGGLVQPGGSLRLSCAASGFTFNTYAMNWVRQAPGKGLEWVARIRSKYNNYATYYAASVKGRFTISRDDSKNSLYLQMNSLKTEDTAVYYCARHGNFGNSYVSWFAYWGQGTLVTVSSASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS GLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVESKYGPPCPPCPAPEAAGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEE MTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFLLYSKLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK (SEQ ID NO: 121) Light chain: QTVVTQEPSLTVSPGGTVTLTCRSSTGAVTTSNYANWVQQKPGQAPRGLIGGTNKRAPGTPARFSGSLLGGKAALTLSGVQPEDEAEYYCALWYSNLWVFGGGTKLTVLGQPKAAPSVTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPSKQSNNKYAASSYLSLTPEQWK SHRSYSCQVTHEGSTVEKTVAPTECS (SEQ ID NO: 126)

[0156] Some CD3-specific antibodies or antigen-binding fragments can be characterized in, for example, U.S. Patent Nos. 10,562,968 and 10,072,088, U.S. Publication No. US2019 / 0382481, the contents of each of which are incorporated herein by reference in their entirety .

[0157] In some embodiments, the CD3 binding arm comprises a heavy chain variable domain comprising the heavy chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 3. In some embodiments, the CD3 binding arm comprises a light chain variable domain comprising the light chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 3. In some embodiments, the CD3 binding arm comprises a heavy chain variable domain and a light chain variable domain, the heavy chain variable domain comprising heavy chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 3 , the light chain variable domain comprising any one of the light chain CDR1, CDR2, and CDR3 of the antibody described in Table 3. In some embodiments, the CD3 binding arm competes for binding to CD3 with an antibody or antigen-binding fragment comprising a heavy chain comprising the heavy chain CDR1, CDR2 of any of the antibodies described in Table 3 , and CDR3, the light chain comprising the light chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 3.

[0158] In some embodiments, the CD3 binding arm comprises a heavy chain comprising the heavy chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 3. In some embodiments, the CD3 binding arm comprises a light chain comprising the light chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 3. In some embodiments, the CD3 binding arm comprises a heavy chain comprising the heavy chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 3 and a light chain comprising the heavy chains described in Table 3 Light chain CDR1, CDR2, and CDR3 of any of the antibodies described above.

[0159] In some embodiments, the CD3 binding arm comprises the heavy chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 3. In some embodiments, the CD3 binding arm comprises the light chain CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 3. In some embodiments, the CD3 binding arm comprises a heavy chain comprising CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 3 and a light chain comprising the CDR1 described in Table 3. CDR1, CDR2, and CDR3 of any of the antibodies. In some embodiments of the multispecific antibodies, the CD3 binding arm comprises a pair of heavy and light chains selected from Table 3. In some embodiments, the GPRC5D binding arm comprises heavy chain CDR1, CDR2, and CDR3 and light chain CDR1, CDR2, and CDR3 of clone CD3B376. In some embodiments, the GPRC5D binding arm comprises heavy chain CDR1, CDR2, and CDR3 and light chain CDR1, CDR2, and CDR3 of clone CD3B219.

[0160] In some embodiments, the CD3 binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 4, heavy chain CDR2 comprising SEQ ID NO: 5, and heavy chain CDR3 comprising SEQ ID NO: 6. In some embodiments, the CD3 binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 4, heavy chain CDR2 comprising SEQ ID NO: 5, heavy chain CDR3 comprising SEQ ID NO: 6, comprising SEQ ID NO: The light chain CDR1 of 1, the light chain CDR2 comprising SEQ ID NO: 2, and the light chain CDR3 comprising SEQ ID NO: 3. The CD3 binding arm can comprise human framework sequences. In some embodiments, the CD3 binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 8. In some embodiments, the CD3 binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 8 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 7. In some embodiments, the CD3 binding arm comprises a heavy chain substantially identical to or identical to SEQ ID NO: 26. In some embodiments, the CD3 binding arm comprises a heavy chain substantially identical to or identical to SEQ ID NO: 26 and a light chain substantially identical to or identical to SEQ ID NO: 27.

[0161] In some embodiments, the CD3 binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 117, heavy chain CDR2 comprising SEQ ID NO: 118, and heavy chain CDR3 comprising SEQ ID NO: 119. In some embodiments, the CD3 binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 117, heavy chain CDR2 comprising SEQ ID NO: 118, heavy chain CDR3 comprising SEQ ID NO: 119, comprising SEQ ID NO: The light chain CDR1 of 123, the light chain CDR2 comprising SEQ ID NO: 124, and the light chain CDR3 comprising SEQ ID NO: 125. The CD3 binding arm can comprise human framework sequences. In some embodiments, the CD3 binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 120. In some embodiments, the CD3 binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 120 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 125. In some embodiments, the CD3 binding arm comprises a heavy chain substantially identical to or identical to SEQ ID NO: 121. In some embodiments, the CD3 binding arm comprises a heavy chain substantially identical to or identical to SEQ ID NO: 121 and a light chain substantially identical to or identical to SEQ ID NO: 126.

[0162] In some embodiments, the CDRs of the heavy chain and / or the light chain are derived from known anti-CD3 antibodies such as, for example, muromonab-CD3 (OKT3), oxixizumab Anti (otelixizumab) (TRX4), teplizumab (MGA031), visilizumab (Nuvion), TR-66 or X35-3, VIT3, BMA030 (BW264 / 56), CLB -T3 / 3, CRIS7, YTH12.5, Fl 11-409, CLB-T3.4.2, TR-66, WT32, SPv-T3b, 11D8, XIII-141, XIII-46, XIII-87, 12F6, T3 / RW2-8C8, T3 / RW2-4B6, OKT3D, M-T301, SMC2, F101.01, UCHT-l, and WT-31.

[0163] In some embodiments, the CD3 binding arm is IgG, or a derivative thereof. In some embodiments, the CD3 binding arm is IgGl, IgG2, IgG3, or IgG4. In some embodiments where the CD3 binding arm has an IgG4 isotype, the CD3 binding arm contains substitutions S228P, L234A, L235A, F405L, and R409K in the Fc region. In some embodiments, the antibodies or antigen-binding fragments bind CD3ε on primary human T cells. In some embodiments, the antibodies or antigen-binding fragments bind CD3ε on primary cynomolgus T cells. In some embodiments, the antibodies or antigen-binding fragments bind CD3ε on primary human and cynomolgus T cells. In some embodiments, the antibodies or antigen-binding fragments activate primary human CD3+ T cells. In some embodiments, the antibodies or antigen-binding fragments activate primary cynomolgus CD4+ T cells.

[0164] In some embodiments, the trispecific antibodies described herein can take any form that has been described in the art for trispecific antibodies. In some embodiments, the trispecific antibodies described herein are constructed based on a bispecific antibody format. This can be achieved by adding a third antigen binding arm to the bispecific antibody. Different formats of bispecific antibodies have been described and recently reviewed by Chames and Baty (2009) Curr Opin Drug Disc Dev 12: 276. In some embodiments, the trispecific antibody comprises a bispecific antibody that is a bivalent antibody, a cross-body, or a bispecific obtained via controlled Fab arm exchange as described in this disclosure Antibody.

[0165] In some embodiments, the trispecific antibodies include IgG-like molecules with complementary CH3 domains to force heterodimerization; recombinant IgG-like dual targeting molecules, wherein each side of the molecule comprises at least two Fab fragments of different antibodies or a part of the Fab fragment; IgG fusion molecules, in which a full-length IgG antibody system is fused to an additional Fab fragment or part of a Fab fragment; Fc fusion molecules, in which a single-chain Fv molecule or a stabilized bivalent antibody system is fused to heavy chain constant domains, Fc regions, or portions thereof; Fab fusion molecules in which different Fab fragments are fused together; ScFv-based antibodies and diabody-based antibodies and heavy chain antibodies (e.g., domain antibodies, nanobodies Antibodies), wherein different single chain Fv molecules or different diabodies or different heavy chain antibodies (eg domain antibodies, nanobodies) are fused to each other or to another protein or carrier molecule.

[0166] In some embodiments, IgG-like molecules with complementary CH3 domain molecules include Triomab / Quadroma (Trion Pharma / Fresenius Biotech), Knobs-into-Holes (Genentech), CrossMAbs (Roche), and electrostatically matched Electrostatically-matched (Amgen), LUZ-Y (Genentech), Strand Exchange Engineered Domain body (SEEDbody) (EMD Serono), Biclonic (Merus), DuoBody (Genmab A / S), and other asymmetric mutations (eg, Zymeworks).

[0167] In some embodiments, recombinant IgG-like dual targeting molecules include Dual Targeting (DT)-Ig (GSK / Domantis), two-in-one Antibody (Genentech), cross-linked monoclonal Antibodies (Cross-linked Mabs) (Karmanos Cancer Center), mAb2 (F-Star) and CovX-body (CovX / Pfizer).

[0168] In some embodiments, IgG fusion molecules include double variable domain (Dual Variable Domain, DVD)-Ig (Abbott), class IgG-like Bispecific antibody (IgG-like Bispecific) (InnClone / Eli Lilly), Ts2Ab (MedImmune / AZ) and BsAb (Zymogenetics), HERCULES (Biogen Idec) and TvAb (Roche).

[0169] In some embodiments, Fc fusion molecules include ScFv / Fc Fusions (Academic Institution), SCORPION (Emergent BioSolutions / Trubion, Zymogenetics / BMS), Dual Affinity Retargeting Technology (Fc-DART) (MacroGenics) and Dual (ScFv ).sub.2-Fab (National Research Center for Antibody Medicine--China).

[0170] In some embodiments, the Fab fusion bispecific antibody comprises F(ab)2 (Medarex / AMGEN), Dual-Action or Bis-Fab (Genentech), Dock-and-Lock (DNL) (ImmunoMedics), Bivalent Bispecific (Biotecnol) and Fab-Fv (UCB-Celltech). ScFv-based antibodies, diabody-based antibodies and domain antibodies include but are not limited to Bispecific T Cell Engager (BiTE) (Micromet), Tandem Diabody (Tandab) (Affimed), Dual Affinity Retargeting Technology (DART) (MacroGenics), Single -chain Diabody (Academic), TCR-like Antibodies (AIT, ReceptorLogics), Human Serum Albumin ScFv Fusion (Merrimack) and COMBODY (Epigen Biotech), dual targeting Nanobodies (Ablynx), dual targeting heavy chain domain antibodies only (dual targeting heavy chain only domain antibody).

[0171] The full-length trispecific antibodies of the present disclosure can be generated using, for example, Fab arm exchange (or half-molecule exchange) between two monospecific bivalent antibodies by virtue of the heavy chain CH3 interface in each half-molecule Substitutions are introduced to facilitate the formation of heterodimers of two antibody half-molecules with different specificities in vitro in a cell-free environment or using co-expression. This Fab arm exchange reaction is the result of disulfide bond isomerization and dissociation-association of CH3 domains. The heavy chain disulfide bonds in the hinge region of the parent monospecific antibody are reduced. The resulting free cysteine ​​of one of the parental monospecific antibodies forms an inter-heavy chain disulfide bond with a cysteine ​​residue of a second parental monospecific antibody molecule, while the CH3 domains of these parental antibodies are Dissociation-association to release and reform. The CH3 domains of the Fab arms can be engineered to favor heterodimerization rather than homodimerization. The resulting product is a bispecific antibody with two Fab arms or half-molecules each binding to a different epitope, such as an epitope on BCMA (or GPRC5D) and an epitope on CD3. A third antigen binding arm can then be introduced into the bispecific antibody, for example into the C-terminus of the first or second heavy chain, which can bind to a third epitope, eg GPRC5D (or BCMA).

[0172] "Homodimerization" as used herein refers to the interaction of two heavy chains having the same CH3 amino acid sequence. As used herein, "homodimer" refers to an antibody having two heavy chains with the same CH3 amino acid sequence.

[0173] "Heterodimerization" as used herein refers to the interaction of two heavy chains with different CH3 amino acid sequences. As used herein, "heterodimer" refers to an antibody having two heavy chains with different CH3 amino acid sequences.

[0174] A "knob-in-hole" strategy (see eg PCT International Publication No. WO 2006 / 028936) can be used to generate full length trispecific antibodies. Briefly, selected amino acids that form the CH3 domain interface in human IgG can be mutated at positions that affect CH3 domain interactions to promote heterodimer formation. Amino acids with small side chains (pores) are introduced into the heavy chain of antibodies that bind the first antigen and amino acids with large side chains (knobs) are introduced into the heavy chain of antibodies that bind the second antigen . After co-expression of the two antibodies, the heavy chain with the "hole" preferentially interacts with the heavy chain with the "knob" resulting in heterodimer formation. Exemplary CH3 substitution pairs forming a knob and a pore (shown as modified position in first CH3 domain of first heavy chain / modified position in second CH3 domain of second heavy chain): T366Y / F405A, T366W / F405W, F405W / Y407A, T394W / Y407T, T394S / Y407A, T366W / T394S, F405W / T394S and T366W / T366S_L368A_Y407V.

[0175] In some embodiments of the trispecific antibodies or trispecific binding fragments described herein, one of the Fc domains comprises mutations T366S, L368A, and Y407V, and the other Fc domain comprises mutation T366W. In some embodiments, the Fc domain of the first heavy chain portion (HC1) of the first antigen binding arm (e.g., CD3 binding arm) comprises mutations T366S, L368A, and Y407V, and the second antigen binding arm and and / or the Fc domain of the second heavy chain portion (HC2) of the third antigen binding arm (eg, the GPRC5D / BCMA binding arm, or the BCMA binding arm) comprises mutation T366W. In some embodiments, the Fc domain of the HC2 of the second and / or third antigen binding arm (e.g., the GPRC5D / BCMA binding arm, or BCMA binding arm) comprises mutations T366S, L368A, and Y407V , and the Fc domain of the HC1 of the first antigen binding arm (eg, CD3 binding arm) comprises mutation T366W.

[0176] Other strategies can be used, such as the use of electrostatic interactions to promote heavy chain heterodimerization by substituting positively charged residues on one CH3 surface and negatively charged residues on a second CH3 surface, as described in US Patent Publication No. US2010 / 0015133; US Patent Publication No. US2009 / 0182127; US Patent Publication No. US2010 / 028637; or US Patent Publication No. US2011 / 0123532. In other strategies, heterodimerization can be promoted by the following substitutions (expressed as modified positions in the first CH3 domain of the first heavy chain / modified positions in the second CH3 domain of the second heavy chain): L351Y_F405AY407V / T394W, T366I_K392M_T394W / F405A_Y407V, T366L_K392M_T394W / F405A_Y407V, L351Y_Y407A / T366A_K409F, L351Y_Y407A / T36 6V K409F Y407A / T366A_K409F, or T350V_L351Y_F405A Y407V / T350V_T366L_K392L_T394W, as described in U.S. Patent Publication No. US2012 / 0149876 or U.S. Patent Publication No. US2013 / 0195849 (Zymeworks).

[0177] In addition to the methods described above, the trispecific antibodies of the present invention can be produced in vitro in a cell-free environment by introducing asymmetric mutations in the CH3 region of two monospecific homodimeric antibodies, and in Formation of a trispecific heterodimeric antibody from two parental monospecific homodimeric antibodies under reducing conditions (to isomerize the disulfide bonds) according to that described in International Patent Publication No. WO2011 / 131746 method. In these approaches, a first monospecific bivalent antibody (e.g., an anti-GPRC5D antibody) and a second monospecific bivalent antibody (e.g., an anti-CD3 antibody) are engineered to have certain promoting heterodivalent antibodies in the CH3 domain. Substitution of polymer stability; the antibodies were incubated together under reducing conditions sufficient to undergo disulfide bond isomerization of the cysteines in the hinge region; thereby generating the trispecific antibody by Fab arm exchange. Culture conditions can optimally be reverted to non-reducing conditions. Exemplary reducing agents that can be used are 2-mercaptoethylamine (2-MEA), dithiothreitol (DTT), dithioerythritol (DTE), glutathione, ginseng (2- Carboxyethyl)phosphine (TCEP), L-cysteine, and β-mercaptoethanol, the reducing agent is preferably selected from the group consisting of 2-mercaptoethylamine, dithiothreitol, and ginseng (2-carboxyethyl)phosphine. For example, at a temperature of at least 20° C. in the presence of at least 25 mM of 2-MEA or in the presence of at least 0.5 mM of dithiothreitol at a pH of 5 to 8 (e.g. at a pH of 7.0) can be used or at a pH of 7.4) for at least 90 min.

[0178] In some embodiments, the trispecific antibody or antigen-binding fragment is IgG, or a derivative thereof. IgG classes are divided into four isotypes in humans: IgGl, IgG2, IgG3 and IgG4. The amino acid sequences of their Fc regions share more than 95% homology, but the amino acid composition and structure of the hinge region show major differences. The Fc region mediates effector functions such as antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). In ADCC, the Fc region of an antibody binds to Fc receptors (FcγRs) on the surface of immune effector cells, such as natural killer cells and macrophages, resulting in phagocytosis or lysis of target cells. In CDC, antibodies kill target cells by triggering the complement cascade on the cell surface. Antibodies described herein include antibodies having such variable domain properties in combination with any IgG isotype, including modified versions in which the Fc sequence has been modified to render different effector functions.

[0179] In many therapeutic antibody applications, Fc-mediated effector functions are not part of the mechanism of action. Effector functions of these Fc mediators may be deleterious and may pose a safety risk by causing off-mechanism toxicity. Modification of effector functions can be achieved by engineering the Fc region to reduce its binding to FcyRs or complement factors. IgG binding to activating (FcyRI, FcyRIIa, FcyRIIIa, and FcyRIIIb) and inhibitory (FcyRIIb) FcyRs or the first component of complement (C1q) depends on residues located in the hinge region and the CH2 domain. Mutations have been introduced into IgGl, IgG2 and IgG4 to reduce or silence Fc functionality. The antibodies described herein may include such modifications.

[0180] In one embodiment, the antibody comprises an Fc region that has one or more of the following properties: (a) reduced effector function when compared to a parental Fc; (b) for FcyRI, FcyRIIa, FcyRIIb, FcyRIIIb, and / or have reduced affinity for FcyRIIIa, (c) reduced affinity for FcyRI, (d) reduced affinity for FcyRIIa, (e) reduced affinity for FcyRIIb, (f) reduced affinity for FcyRIIIb, or (g) reduced affinity for FcyRIIIa affinity is reduced.

[0181] In some embodiments, the antibodies or antigen-binding fragments are IgG, or derivatives thereof, such as IgGl, IgG2, IgG3, and IgG4 isotypes. In some embodiments where the antibody has an IgG1 isotype, the antibody contains a L234A, L235A, D265S and / or K409R substitution(s) in the Fc region. In some embodiments where the antibody has an IgG4 isotype, the antibody contains S228P, L234A, and L235A substitutions in the Fc region. The antibodies described herein may include such modifications.

[0182] In some embodiments, the Fc domains of the multispecific antibodies described herein each comprise one or more mutations selected from L234A, L235A, and D265S. In some embodiments, the Fc domains of HC1 and HC2 each comprise mutations L234A, L235A, and D265S.

[0183] In some embodiments, the Fc domain of one of the heavy chain portions of a multispecific antibody described herein further comprises one or more mutations that reduce Fc binding to Protein A. In some embodiments, the Fc domains of one of the heavy chain portions comprise mutations H435R and / or Y436F. In some embodiments, the Fc domain of the HC2 of the second and / or third antigen binding arm (eg, GPRC5D / BCMA binding arm, or BCMA binding arm) comprises mutations H435R and / or Y436F.

[0184] In various embodiments, the third antigen binding arm is operably linked to the Fc domain of the first or second antigen binding arm. In some embodiments, the linker is a peptide linker and can include any naturally occurring amino acid. Exemplary amino acids that can be included into the linker are Gly, Ser, Pro, Thr, Glu, Lys, Arg, lie, Leu, His, and The. The linker should be of sufficient length to connect the third antigen-binding arm and either the first or the second antigen-binding arm in such a way that they form the correct configuration relative to each other so that they retain the desired Activity, such as binding to a third antigen (eg, BCMA or GPRC5D).

[0185] In some embodiments of the trispecific antibodies described herein, the HC1 comprises the VH1, CH1 domain, the Fc domain, linker, and the second antigen-binding arm of the first antigen-binding arm from N to C-terminal Three antigen binding arms.

[0186] In some embodiments of the trispecific antibodies described herein, the HC2 comprises the second antigen-binding arm, the Fc domain, linker, and the third antigen-binding arm from N to C-terminus.

[0187] In various embodiments, the scFv used in the multispecific antibody described herein comprises VH, linker, and VL (VH-L-VL), or the VL, The linker, and the VH (VL-L-VH). In some embodiments, the scFv comprises the VL, the linker, and the VH from N to C-terminus (VL-L-VH). In some embodiments, the scFv comprises the VH, the linker, and the VL (VH-L-VL) from N to C-terminus.

[0188] Linkers can be about 5 to 50 amino acids long. In some embodiments, the linker is about 10 to 40 amino acids long. In some embodiments, the linker is about 10 to 35 amino acids long. In some embodiments, the linker is about 10 to 30 amino acids long. In some embodiments, linkers are about 10-25 amino acids long. In some embodiments, the linker is about 10-20 amino acids long. In some embodiments, the linker is about 15-20 amino acids long. In some embodiments, the linker is 6 amino acids long. In some embodiments, the linker is 7 amino acids long. In some embodiments, the linker is 8 amino acids long. In some embodiments, the linker is 9 amino acids long. In some embodiments, the linker is 10 amino acids long. In some embodiments, the linker is 11 amino acids long. In some embodiments, the linker is 12 amino acids long. In some embodiments, the linker is 13 amino acids long. In some embodiments, the linker is 14 amino acids long. In some embodiments, the linker is 15 amino acids long. In some embodiments, the linker is 16 amino acids long. In some embodiments, the linker is 17 amino acids long. In some embodiments, the linker is 18 amino acids long. In some embodiments, the linker is 19 amino acids long. In some embodiments, the linker is 20 amino acids long. In some embodiments, the linker is 21 amino acids long. In some embodiments, the linker is 22 amino acids long. In some embodiments, the linker is 23 amino acids long. In some embodiments, the linker is 24 amino acids long. In some embodiments, the linker is 25 amino acids long. In some embodiments, the linker is 26 amino acids long. In some embodiments, the linker is 27 amino acids long. In some embodiments, the linker is 28 amino acids long. In some embodiments, the linker is 29 amino acids long. In some embodiments, the linker is 30 amino acids long. In some embodiments, the linker is 31 amino acids long. In some embodiments, the linker is 32 amino acids long. In some embodiments, the linker is 33 amino acids long. In some embodiments, the linker is 34 amino acids long. In some embodiments, the linker is 35 amino acids long. In some embodiments, the linker is 36 amino acids long. In some embodiments, the linker is 37 amino acids long. In some embodiments, the linker is 38 amino acids long. In some embodiments, the linker is 39 amino acids long. In some embodiments, the linker is 40 amino acids long. Exemplary linkers that can be used are Gly rich linkers, Gly and Ser containing linkers, Gly and Ala containing linkers, Ala and Ser containing linkers, and other flexible linkers.

[0189] Other linker sequences may include immunoglobulin hinge regions, portions of CL or CH1 derived from any immunoglobulin heavy or light chain isotype. Exemplary linkers that can be used are shown in Table 4. Additional linkers are described, eg, in International Patent Publication No. WO2019 / 060695.

[0190] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 25.

[0191] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 163.

[0192] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 127.

[0193] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 128.

[0194] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 129.

[0195] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 130.

[0196] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 131.

[0197] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 132.

[0198] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 133.

[0199] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 134.

[0200] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 135.

[0201] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 136.

[0202] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 137.

[0203] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 138.

[0204] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 139.

[0205] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 140.

[0206] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 141.

[0207] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 142.

[0208] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 143.

[0209] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 144.

[0210] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 145.

[0211] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 146.

[0212] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 147.

[0213] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 148.

[0214] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 149.

[0215] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 150.

[0216] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 151.

[0217] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 152.

[0218] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 153.

[0219] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 154.

[0220] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 155.

[0221] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 156.

[0222] In some embodiments, the linker comprises the amino acid sequence of SEQ ID NO: 157. Table 4. Exemplary linker sequences linker name amino acid sequence SEQ ID NO: linker 1 GGSEGKSSGSGSESKSTGGS 25 linker 2 GGGSGGGS 127 linker 3 GGGSGGGSGGGS 128 linker 4 GGGSGGGSGGGSGGGS 129 linker 5 GGGSGGGSGGGSGGGSGGGS 130 linker 6 GGGGSGGGGSGGGGS 131 connexon 7 GGGGSGGGGSGGGGSGGGGS 163 connexon 8 GGGGSGGGGSGGGGSGGGGSGGGGS 132 connexon 9 GSTSGSGKPGSGEGSTKG 133 connexon 10 IRPRAIGGSKPRVA 134 connexon 11 GKGGSGKGGSGKGGS 135 linker 12 GGKGSGGKGSGGKGS 136 linker 13 GGGKSGGGKSGGGKS 137 linker 14 GKGKSGKGKSGKGKS 138 connexon 15 GGGKSGGKGSGKGGS 139 linker 16 GKPGSGKPGSGKPGS 140 connexon 17 GKPGSGKPGSGKPGSGKPGS 141 linker 18 GKGKSGKGKSGKGKSGKGKS 142 linker 19 STAGDTHLGGEDFD 143 Linker 20 GEGGSGEGGSGEGGS 144 Linker 21 GGEGSGGEGSGGEGS 145 Linker 22 GEGESGEGESGEGES 146 Linker 23 GGGESGGEGSGEGGS 147 Linker 24 GEGESGEGESGEGESGEGES 148 Linker 25 GSTSGSGKPGSGEGSTKG 149 Linker 26 PRGASKSGSASQTGSAPGS 150 Linker 27 GTAAAGAGAAGGAAAGAAG 151 Linker 28 GTSGSSGSGSGGSGSGGGG 152 Linker 29 GKPGSGKPGSGKPGSGKPGS 153 Linker 30 GSGS 154 linker 31 APAPAPAPAP 155 Linker 32 APAPAPAPAPAPAPAPAPAP 156 linker 33 AEAAAKEAAAKEAAAAKEAAAAKEAAAAKAAA 157

[0223] In one embodiment, the HC1 of the BCMA x GPRC5D x CD3 trispecific antibody comprises an amino acid sequence substantially identical or identical to SEQ ID NO: 26.

[0224] In one embodiment, the LC of the BCMA x GPRC5D x CD3 trispecific antibody comprises an amino acid sequence substantially identical or identical to SEQ ID NO: 27.

[0225] In one embodiment, the GPRC5D / BCMA binding arm of the BCMA x GPRC5D x CD3 trispecific antibody comprises an amino acid sequence substantially identical or identical to SEQ ID NO: 28.

[0226] In one embodiment, the CD3 / GPRC5D-conjugated HCl of the BCMA x GPRC5D x CD3 trispecific antibody comprises an amino acid sequence substantially identical or identical to SEQ ID NO: 29.

[0227] In one embodiment, the LC of the BCMA x GPRC5D x CD3 trispecific antibody comprises an amino acid sequence substantially identical or identical to SEQ ID NO: 30.

[0228] In one embodiment, the BCMA binding arm comprises an amino acid sequence substantially identical or identical to SEQ ID NO: 31.

[0229] In one embodiment, provided herein is an isolated trispecific antibody, or trispecific binding fragment thereof, comprising: a) a CD3 binding arm comprising a heavy chain (HC1) and a light chain (LC) and b) a GPRC5D / BCMA binding arm, wherein HC1 comprises an amino acid sequence substantially identical to or identical to SEQ ID NO: 26, and LC comprises an amino acid sequence substantially identical to or identical to SEQ ID NO: 27 , and the GPRC5D / BCMA binding arm comprises an amino acid sequence substantially identical or identical to SEQ ID NO: 28.

[0230] In one embodiment, provided herein is an isolated trispecific antibody, or trispecific binding fragment thereof, comprising: a) a CD3 binding arm comprising a heavy chain (HC1) and a light chain (LC) and b) a GPRC5D / BCMA binding arm, wherein HC1 comprises the amino acid sequence of SEQ ID NO: 26, LC comprises the amino acid sequence of SEQ ID NO: 27, and the GPRC5D / BCMA binding arm comprises SEQ ID NO: 28 the amino acid sequence. In one embodiment, provided herein is an isolated trispecific antibody, or trispecific binding fragment thereof, comprising: a) a CD3 binding arm comprising a heavy chain (HC1) and a light chain (LC) , wherein the HC1 further comprises the GPRC5D binding arm; and b) a BCMA binding arm, wherein HC1 comprises an amino acid sequence substantially identical to or identical to SEQ ID NO: 29, and LC comprises substantially identical to SEQ ID NO: 30 Or an amino acid sequence identical thereto, and the BCMA binding arm comprises an amino acid sequence substantially identical or identical to SEQ ID NO: 31.

[0232] In one embodiment, provided herein is an isolated trispecific antibody, or trispecific binding fragment thereof, comprising: a) a CD3 binding arm comprising a heavy chain (HC1) and a light chain (LC) , wherein the HC1 further comprises the GPRC5D binding arm; and b) a BCMA binding arm, wherein HC1 comprises the amino acid sequence of SEQ ID NO: 29, LC comprises the amino acid sequence of SEQ ID NO: 30, and the BCMA binding arm Comprising the amino acid sequence of SEQ ID NO: 31.

[0233] In one embodiment, the BCMA x GPRC5D x CD3 trispecific antibody is BGCB463.

[0234] In one embodiment, the BCMA x GPRC5D x CD3 trispecific antibody is BGCB491.

[0235] In addition to the BCMA x GPRC5D x CD3 multispecific antibody or antigen-binding fragment, a polynucleotide sequence capable of encoding the BCMA x GPRC5D x CD3 multispecific antibody or antigen-binding fragment is also provided. Also provided are vectors comprising said polynucleotides, such as cells expressing the BCMAxGPRC5DxCD3 multispecific antibodies or antigen-binding fragments provided herein. Cells capable of expressing the disclosed vectors are also described. These cells can be mammalian cells (such as 293F cells, CHO cells), insect cells (such as Sf7 cells), yeast cells, plant cells, or bacterial cells (such as E. coli). The antibodies can also be produced by fusion of tumor cells. The antibodies can also be produced recombinantly.

[0236] Polynucleotides encoding recombinant antigen binding proteins are also within the scope of the present disclosure. In some embodiments, the polynucleotides (and the peptides they encode) include a leader sequence. Any preamble sequence known in the art can be used. A leader sequence may include, but is not limited to, a restriction site or a translation start site.

[0237] The BCMAxGPRC5DxCD3 multispecific antibodies or antigen-binding fragments described herein include variants having single or multiple amino acid substitutions, deletions, or additions that retain the BCMAx Biological properties (eg, binding affinity or immune effector activity) of the GPRC5D x CD3 multispecific antibody or antigen-binding fragment. In the context of the present invention, the following notations are used to describe mutations, unless otherwise indicated; i) substitution of an amino acid in a specified position is written, for example, K409R, which represents the substitution of arginine for a lysine in position 409; and ii) use of specific three or one letter codes (including codes Xaa and X) to designate any amino acid residue in a particular variant. Thus, substitution of arginine for a lysine in position 409 is designated: K409R, or substitution of any amino acid residue for a lysine in position 409 is designated K409X. In case the lysine in position 409 is deleted, it is indicated with K409*. Variants having single or multiple amino acid substitutions, deletions, or additions can be produced by those with ordinary knowledge.

[0238] Such variants may include: (a) variants in which one or more amino acid residues are substituted with conservative or non-conservative amino acids, (b) variants in which one or more amino acid residues are added to Polypeptides or variants deleted from polypeptides, (c) variants in which one or more amino acids include substituents, and (d) variants in which the polypeptide is fused to another peptide or polypeptide (such as a fusion partner, protein tag, or other Chemical moieties that can confer useful properties on polypeptides, such as, for example, variants fused to epitopes of antibodies, polyhistidine sequences, biotin moieties, and the like). The antibodies or antigen-binding fragments described herein may include variants in which amino acid residues at conserved or non-reserved positions from one species are substituted with corresponding residues from another species. In other embodiments, amino acid residues at non-conservative positions are substituted with conservative or non-conservative residues. Techniques for obtaining such variants, including genetic (deletion, mutation, etc.), chemical, and enzymatic techniques, are known to those of ordinary skill in the art.

[0239] The BCMA x GPRC5D x CD multispecific antibodies or antigen-binding fragments described herein may embody several antibody isotypes, such as IgM, IgD, IgG, IgA, and IgE. In some embodiments, the antibody is of IgG1, IgG2, IgG3, or IgG4 isotype, preferably IgG1 or IgG4 isotype. The specificity of an antibody or antigen-binding fragment thereof is largely determined by the amino acid sequence and arrangement of the CDRs. Thus, the CDRs of one isotype can be transferred to another without changing antigen specificity. Alternatively, techniques have been established to isotype-switch fusionomas from producing one antibody to another (isotype-switching) without altering antigen specificity. Accordingly, such antibody isotypes are within the scope of such antibodies or antigen-binding fragments.

[0240] A BCMA x GPRC5D x CD3 multispecific antibody or antigen-binding fragment described herein may have an IC50 value of at least 5.9 nM for APRIL binding. The IC50 of the BCMA x GPRC5D x CD3 multispecific antibody or antigen-binding fragment can be determined by various methods known in the art, such as ELISA-based methods or flow cytometry (FACS). IC50 was measured by ELISA with plate-bound BCMA and the presence and absence of BCMA x GPRC5D x CD3 multispecific antibody or antigen-binding fragment and using various concentrations of APRIL. A BCMA x GPRC5D x CD3 multispecific antibody or antigen-binding fragment that blocks the binding of APRIL to BCMA "blocks APRIL as measured by ELISA".

[0241] Also provided are vectors comprising the polynucleotides described herein. These vectors can be expression vectors. Recombinant expression vectors containing sequences encoding polypeptides of interest are thus contemplated to be within the scope of the present disclosure. The expression vector may contain one or more additional sequences, such as, but not limited to, regulatory sequences (eg, promoters, enhancers), selectable markers, and polyadenylation signals. Vector systems for transforming a wide variety of host cells are well known and include, but are not limited to, plastids, phagemids, cosmids, baculoviruses, bacmids, artificial bacteria Chromosome (BAC), Artificial Yeast Chromosome (YAC), and other bacterial, yeast, and viral vectors.

[0242] Recombinant expression vectors within the scope of this embodiment include synthetic, genomic, or cDNA-derived nucleic acid segments encoding at least one recombinant protein operably linked to appropriate regulatory elements. Such regulatory elements may include transcriptional promoters, sequences encoding suitable mRNA ribosomal binding sites, and sequences that control termination of transcription and translation. Expression vectors, especially mammalian expression vectors, may also include one or more non-transcribed elements, such as an origin of replication, a suitable promoter and enhancer linked to the gene to be expressed, other 5' or 3' flanking non-transcribed elements. sequence, 5' or 3' untranslated sequences (such as necessary ribosome binding sites), polyadenylation sites, splice donor and acceptor sites, or transcription termination sequences. An origin of replication that confers the ability to replicate in the host may also be incorporated.

[0243] Transcriptional and translational control sequences in expression vectors for transformation of vertebrate cells may be provided by viral sources. Exemplary vectors can be constructed as described in Okayama and Berg, 3 Mol. Cell. Biol. 280 (1983).

[0244] In some embodiments, the multispecific antibody coding sequence or antigen-binding fragment coding sequence is placed under the control of a strong constitutive promoter, such as the promoter of the following gene: hypoxanthine phosphoribosyltransferase (HPRT ), adenosine deaminase, pyruvate kinase, β-actin, human myosin, human heme, human muscle creatine, and others. In addition, many viral promoters function constitutively in eukaryotic cells and are suitable for use with the described examples. Such viral promoters include but are not limited to cytomegalovirus (CMV) immediate early promoter, SV40 early and late promoters, mouse mammary tumor virus (MMTV) promoter, Moloney leukemia virus (Maloney leukemia virus) Chest of long terminal repeat (LTR), human immunodeficiency virus (HIV), Epstein-Barr virus (EBV), Rous sarcoma virus (RSV), and other retroviruses, and Herpes Simplex Virus Glycoside kinase promoter. In one embodiment, the coding sequence of the BCMA x GPRC5D x CD3 trispecific antibody or antigen-binding fragment thereof is placed under the control of an inducible promoter, such as metallothionein promoter, tetracycline inducible promoter, doxyl Doxycycline-inducible promoters, promoters containing one or more interferon-stimulated response element (ISRE), such as protein kinase R 2',5'-oligoadenylate synthase, Mx gene, ADAR1, and the like.

[0245] The vectors described herein may contain one or more internal ribosome entry sites (IRES). Incorporation of IRES sequences into fusion vectors can be beneficial in enhancing the expression of some proteins. In some embodiments, the vector system will include one or more polyadenylation sites (eg, SV40), which may be upstream or downstream of any of the foregoing nucleic acid sequences. Vector components may be linked adjacently, or arranged in a manner that provides optimal spacing for expression of the gene product (i.e., by introducing "spacer" nucleotides between ORFs), or otherwise place. Regulatory elements such as IRES motifs can also be arranged to provide optimal spacing for performance.

[0246] The vectors may contain selectable markers, which are well known in the art. Selectable markers include positive and negative selectable markers, such as antibiotic resistance genes (e.g. neomycin resistance gene, hygromycin resistance gene, kanamycin resistance gene, tetracycline resistance gene, Penicillin resistance gene, puromycin (puromycin) resistance gene, blasticidin (blasticidin) resistance gene), glutamate synthase gene, HSV-TK, for ganciclovir (ganciclovir) selection HSV-TK derivatives, or the bacterial purine nucleoside phosphorylase gene for 6-methylpurine selection (Gadi et al., 7 Gene Ther. 1738-1743 (2000)). The nucleic acid sequence encoding the selectable marker or the cloning site can be upstream or downstream of the nucleic acid sequence encoding the polypeptide of interest or the cloning site.

[0247] The vectors described herein can be used to transform various cells with the gene encoding the antibody or antigen-binding fragment. For example, the vectors can be used to produce cells that produce BCMA x GPRC5D x CD3 multispecific antibodies or antigen-binding fragments. Accordingly, another aspect features host cells transformed with a vector comprising a protein encoding an antibody or antigen-binding fragment thereof that binds BCMA, GPRC5D, and CD3, such as the antibodies or antigen-binding fragments described and exemplified herein. nucleic acid sequence.

[0248] Many techniques for introducing foreign genes into cells are known in the art and can be used to construct recombinant cells for carrying out the methods described and exemplified herein. The technique used should provide stable transfer of the heterologous gene sequence to the host cell so that the heterologous gene sequence can be inherited and expressed by the progeny of the cell without interference with the essential developmental and physiological functions of the recipient cell. Techniques that may be used include, but are not limited to, chromosomal transfer (e.g., cell fusion, chromosome-mediated gene transfer, microcell-mediated gene transfer), physical methods (e.g., transfection, spheroplast fusion, microinjection, electroporation). perforation, liposome vehicles), viral vector transfer (eg, recombinant DNA viruses, recombinant RNA viruses) and the like (described in Cline, 29 Pharmac. Ther. 69-92 (1985)). Calcium phosphate precipitation and polyethylene glycol (PEG)-induced fusion of bacterial protoplasts with mammalian cells can also be used to transform cells.

[0249] Cells suitable for expressing the BCMA x GPRC5D x CD3 multispecific antibody or antigen-binding fragment described herein are preferably eukaryotic cells, more preferably cells derived from plants, rodents, or humans, such as but Not limited to NSO, CHO, CHOK1, perC.6, Tk-ts13, BHK, HEK293 cells, COS-7, T98G, CV-1 / EBNA, L cells, C127, 3T3, HeLa, NS1, Sp2 / 0 myeloma cells , and BHK cell lines, and others. In addition, antibody expression can be achieved using fusionoma cells. Methods for producing fusionomas are well established in the art.

[0250] Cells transformed with the expression vectors described herein can be selected or screened for recombinant expression of the antibodies or antigen-binding fragments described herein. Recombination-positive cells are expanded and screened for subclones exhibiting a desired phenotype, such as high expression levels, enhanced growth properties, or production, e.g., due to protein modifications or modified post-translational The ability to modify a protein to have desired biochemical characteristics. These phenotypes may be due to intrinsic properties of a given subclonal or due to mutations. Mutations can be achieved through the use of chemicals, UV wavelength light, radiation, viruses, insertional mutagens, inhibition of DNA mismatch repair, or a combination of these methods. Therapeutic compositions and methods of treatment using multispecific antibodies and multispecific antigen-binding fragments thereof

[0251] The bispecific antibodies discussed above (eg, the BCMA x GPRC5D x CD3 trispecific antibodies discussed above) can be used in therapy. In particular, such bispecific antibodies are useful in the treatment of cancer. Also provided herein are therapeutic compositions comprising a therapeutically effective amount of a multispecific antibody or multispecific antigen-binding fragment described herein and a pharmaceutically acceptable carrier for use in the treatment of a hyperproliferative disorder in a mammal . In a preferred embodiment, the multispecific antibody is a BCMA x GPRC5D x CD3 multispecific antibody as described herein, or a multispecific antigen-binding fragment thereof, and more preferably a BCMA x as described herein GPRC5D x CD3 trispecific antibody, or BCMA x GPRC5D x CD3 trispecific antigen-binding fragment thereof. In one embodiment, the pharmaceutical composition is used to treat GPRC5D and / or BCMA-expressing cancers, including (but not limited to) the following: GPRC5D and / or BCMA-expressing B-cell cancers, such as multiple myeloma (MM ), including smoldering multiple myeloma (SMM); and other undiagnosed cancers that manifest GPRC5D and / or BCMA. In some embodiments, the GPRC5D and / or BCMA expressing cancer is a relapsed or refractory form of lymphoma, such as a relapsed or refractory form of multiple myeloma. Specific trispecific antibodies that may be used to treat cancer, such as hematological cancers, including the specific cancers discussed above, include antibodies BGCB463 and BGCB491.

[0252] In some embodiments, the BCMA x GPRC5D x CD3 trispecific antibody or binding fragment thereof is used to treat R / R multiple myeloma.

[0253] In some embodiments, the subject receiving the BCMA x GPRC5D x CD3 trispecific antibody or binding fragment thereof has received prior therapy. For example, the subject may have received one or more therapeutic agents, such as proteasome inhibitors (PIs) (e.g., proteasome inhibitors (marizomib (salinosporamide A)), carba Carfilzomib, Ixazomib), immunomodulatory drugs (IMiDs), bispecific agents, CAR-T therapy, and / or anti-CD38 antibodies for the treatment of multiple myeloma.

[0254] The pharmaceutical composition provided herein comprises: a) an effective amount of the multispecific antibody or antibody fragment of the present invention, and b) a pharmaceutically acceptable carrier, which may be inert or physiologically active. In a preferred embodiment, the multispecific antibody is a BCMA x GPRC5D x CD3 multispecific antibody as described herein, or a multispecific antigen-binding fragment thereof, and more preferably a BCMA x as described herein GPRC5D x CD3 trispecific antibody, or BCMA x GPRC5D x CD3 trispecific antigen-binding fragment thereof. As used herein, the term "pharmaceutically acceptable carrier" includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, and the like that are physiologically compatible. Examples of suitable carriers, diluents and / or excipients include one or more of water, saline, phosphate buffered saline, dextrose, glycerol, ethanol, and the like, and any combination thereof. In many cases, it will be preferable to include isotonic agents such as sugars, polyols, or sodium chloride into the compositions. In particular, relevant examples of suitable carriers include: (1) Dulbecco's phosphate buffered saline, pH about 7.4, with or without about 1 mg / mL to 25 mg / mL human serum albumin, (2) 0.9% saline (0.9% w / v sodium chloride (NaCl)), and (3) 5% (w / v) dextrose; and may also contain antioxidants (such as tryptamine) and stabilizers (such as Tween 20®).

[0255] The compositions herein may also include additional therapeutic agents as desired for the treatment of a particular condition. Preferably, the multispecific antibody or antibody fragment and the complementary active compound will have complementary activities that do not adversely affect each other. In some embodiments, the further therapeutic agent is cytarabine, anthracycline, histamine dihydrochloride, or interleukin-2. In some embodiments, the further therapeutic agent is a chemotherapeutic agent, an anti-CD38 agent, an immunomodulatory imide drug (IMiD), an immune checkpoint inhibitor, an immune costimulator, a gamma secretase inhibitor, a T cell enhancer , or any combination thereof. In some embodiments, the further therapeutic agent is an anti-CD38 agent, such as an anti-CD38 antibody (eg, daratumuab). In some embodiments, the further therapeutic agent is an immunomodulatory imide drug (IMiD), such as lenalidomide and pomalidomide. In some embodiments, the further therapeutic agent is an immune checkpoint inhibitor, such as anti-PD-1 and anti-T cell immune receptor with Ig and ITIM domains (TIGIT). In some embodiments, the further therapeutic agent is an immune costimulator, such as an agent targeting CD137 (eg, a CD137 costimulatory bispecific antibody). In some embodiments, the further therapeutic agent is a T cell enhancer, such as IL-2 supplementation.

[0256] The compositions of the present invention may take a variety of forms. These include, for example, liquid, semi-solid, and solid dosage forms, although the preferred form depends on the intended mode of administration and therapeutic application. Typical preferred compositions are in the form of injectable or infusible solutions. The preferred mode of administration is parenteral (eg, intravenous, intramuscular, intraperitoneal, subcutaneous). In preferred embodiments, the compositions of the invention are administered intravenously as a bolus or by continuous infusion over a period of time. In another preferred embodiment, they are injected by intramuscular, subcutaneous, intraarticular, intrasynovial, intratumoral, peritumoral, intralesional, or perilesional routes to produce local and systemic therapeutic effects .

[0257] Sterile compositions for parenteral administration can be sterilized by incorporating the antibody, antibody fragment or antibody conjugate (conjugate) of the present invention in the desired amount in an appropriate solvent, followed by microfiltration. bacteria to prepare. In terms of solvents or vehicles, water, saline, phosphate buffered saline, dextrose, glycerol, ethanol, and the like, and combinations thereof can be used. In many cases, it will be preferable to include isotonic agents such as sugars, polyols, or sodium chloride in the composition. These compositions may also contain adjuvants, especially wetting, isotonic, emulsifying, dispersing and stabilizing agents. Sterile compositions for parenteral administration can also be prepared in the form of sterile solid compositions which can be dissolved in sterile water or any other sterile medium for injection at the time of use.

[0258] Multispecific antibodies or antibody fragments can also be administered orally. As a solid composition for oral administration, tablets, pills, powders (gelatin capsules, sachets), or granules can be used. In these compositions, the active ingredient according to the invention is mixed with one or more inert diluents, such as starch, cellulose, sucrose, lactose, or silicon dioxide, under a stream of argon. These compositions may also contain substances other than diluents, such as one or more lubricants (such as magnesium stearate or talc), coloring agents, coatings (dragnes) or glazes.

[0259] For liquid compositions for oral administration, pharmaceutically acceptable solutions, suspensions, emulsions, syrups and elixirs containing inert diluents such as water, ethanol, glycerin, vegetable oil or paraffin oil may be used. . These compositions may contain substances other than diluents, such as wetting, sweetening, thickening, flavoring or stabilizing products.

[0260] Dosage depends on the effect desired, the duration of treatment and the route of administration used; adult oral dosages usually range from 5 mg to 1000 mg per day, and unit doses contain the active substance in the range of 1 mg to 250 mg. In general, a physician will determine the appropriate dosage depending on the age, weight and any other particular factors of the subject to be treated.

[0261] Also provided herein are methods for killing GPRC5D and / or BCMA+ by administering to a patient in need thereof binding to the GPRC5D and / or BCMA and capable of recruiting T cells to kill the GPRC5D and / or Multispecific antibody against BCMA+ cells (ie, T cell redirection). Any of the multispecific antibodies or antibody fragments of the invention may be used therapeutically. For example, in one embodiment, the BCMA x GPRC5D x CD3 multispecific antibody can be used therapeutically to treat cancer in a subject.

[0262] In preferred embodiments, the multispecific antibodies or antibody fragments of the invention are used to treat hyperproliferative disorders in mammals. In a more preferred embodiment, one of the pharmaceutical compositions disclosed above and comprising the multispecific antibody or antibody fragment of the present invention is used to treat a hyperproliferative disorder in a mammal. In one embodiment, the disorder is cancer. In particular, the cancer is a GPRC5D and / or BCMA expressing cancer, including but not limited to the following: GPRC5D and / or BCMA expressing B cell carcinoma, such as multiple myeloma (MM), including smoldering multiple myeloma Myeloma (SMM); and other undiagnosed cancers that exhibit GPRC5D and / or BCMA. In some embodiments, the GPRC5D and / or BCMA expressing cancer is a relapsed or refractory form of lymphoma, such as a relapsed or refractory form of multiple myeloma. In a preferred embodiment, the multispecific antibody is a BCMA x GPRC5D x CD3 multispecific antibody as described herein, or a multispecific antigen-binding fragment thereof, and more preferably a BCMA x as described herein GPRC5D x CD3 trispecific antibody, or BCMA x GPRC5D x CD3 trispecific antigen-binding fragment thereof.

[0263] Therefore, the pharmaceutical composition of the present invention can be used to treat or prevent various cancers or diseases, including (but not limited to) the following: GPRC5D and / or BCMA-expressing cancers, including (but not limited to) the following: GPRC5D and / or BCMA manifesting B / plasma cell carcinoma such as acute multiple myeloma (MM) or premalignant myeloma (such as MGUS (Monoclonal Gammopathy of Undetermined Significance) and SMM (Smoldering Multiple myeloma) and plasmacytoma; and other undiagnosed cancers manifesting GPRC5D and / or BCMA, or other plasma cell disorders such as amyloidosis and lupus . In some embodiments, the GPRC5D and / or BCMA expressing cancer is a relapsed or refractory form of lymphoma, such as a relapsed or refractory form of multiple myeloma.

[0264] Likewise, further provided herein is a method for inhibiting the growth of a selected cell population comprising, in the presence of peripheral blood mononuclear cells (PBMCs), GPRC5D and / or BCMA expressing target cells, or containing These target cell tissues are contacted with an effective amount of a multispecific antibody or antibody fragment of the invention, alone or in combination with other cytotoxic or therapeutic agents. BCMAxGPRC5DxCD3 antibodies that block the binding of ligands (APIL, BAFF, and others) to BCMA and GPRC5D can block BCMA- and GPRC5D-mediated signaling and lead to inhibition or cell death of target cells. In a preferred embodiment, the multispecific antibody is a BCMA x GPRC5D x CD3 multispecific antibody as described herein, or a multispecific antigen-binding fragment thereof, and more preferably a BCMA x as described herein GPRC5D x CD3 trispecific antibody, or BCMA x GPRC5D x CD3 trispecific antigen-binding fragment thereof.

[0265] In some embodiments, the methods described herein involve administering a multispecific antibody or a pharmaceutical composition comprising the multispecific antibody, further involving administering another therapeutic agent. Suitable additional therapeutic agents include, but are not limited to, anti-CD38 agents, immunomodulatory imide drugs (IMiDs), immune checkpoint inhibitors, immune costimulators, gamma secretase inhibitors, T cell enhancers (e.g., IL-2 additive), tocilizumab, or any combination thereof. In some embodiments, the further therapeutic agent is an anti-CD38 agent, such as an anti-CD38 antibody (eg, daratumuab). In some embodiments, the further therapeutic agent is an immunomodulatory imide drug (IMiD), such as lenalidomide and pomalidomide. In some embodiments, the further therapeutic agent is an immune checkpoint inhibitor, such as anti-PD-1 and anti-T cell immune receptor with Ig and ITIM domains (TIGIT). In some embodiments, the further therapeutic agent is an immune costimulator, such as an agent targeting CD137 (eg, a CD137 costimulatory bispecific antibody). In the presence of T cell redirecting antibodies such as the BCMAx GPRC5D x CD3 trispecific antibody described here, use of low affinity CD137 binders with conditional agonism can enhance antitumor activity and potentially improve T cell Persistence. In some embodiments, the further therapeutic agent is cytarabine, anthracycline, histamine dihydrochloride, or interleukin-2. In some embodiments, the further therapeutic agent is a chemotherapeutic agent. Methods for inhibiting the growth of selected cell populations can be performed in vitro, in vivo, or ex vivo.

[0266] Examples of in vitro uses include treatment of autologous bone marrow to kill diseased or malignant cells prior to transplantation into the same patient; and prevention of graft-versus-host disease (GVHD); treatment of cell cultures to kill All but the desired variant of the antigen of interest are not expressed; or all cells expressing the variant of the undesired antigen are killed. The conditions for non-clinical in vitro use can be readily determined by those having ordinary knowledge in the art.

[0267] An example of clinical ex vivo use is the removal of tumor cells from the bone marrow prior to autologous bone marrow transplantation for the treatment of cancer. Treatment can be performed as follows. Bone marrow is obtained from a patient or other individual and then cultured in a serum-containing medium to which the cytotoxic agent of the invention is added. Concentrations range from about 10 µM to 1 µM for 30 minutes to about 48 hours at about 37°C. The exact conditions of concentration and time (ie dosage) of incubation can be easily determined by those skilled in the art. After culturing, the bone marrow cells are washed with serum-containing medium and returned to the patient by intravenous infusion according to known methods. These processed bone marrow cell lines use standard medical equipment in cases where the patient is receiving other treatments such as ablative chemotherapy or total body radiation in the time between bone marrow harvest and reinfusion Store frozen in liquid nitrogen.

[0268] In clinical in vivo use, a therapeutically effective amount of a multispecific antibody or antigen-binding fragment is administered to a subject in need thereof. For example, the BCMA x GPRC5D x CD3 multispecific antibodies and multispecific antigen-binding fragments thereof can be used to treat GPRC5D and / or BCMA expressing cancers in a subject in need thereof. In some embodiments, the GPRC5D and / or BCMA expressing cancer is a B cell cancer, such as multiple myeloma (MM), including smoldering multiple myeloma (SMM). In some embodiments, the GPRC5D and / or BCMA expressing cancer is a relapsed or refractory form of lymphoma, such as a relapsed or refractory form of multiple myeloma. In a preferred embodiment, the multispecific antibody is a BCMA x GPRC5D x CD3 multispecific antibody as described herein, or a multispecific antigen-binding fragment thereof, and more preferably a BCMA x as described herein GPRC5D x CD3 trispecific antibody, or BCMA x GPRC5D x CD3 trispecific antigen-binding fragment thereof. In some embodiments, the subject is a mammal, preferably a human. In some embodiments, the multispecific antibody or antigen-binding fragment will be administered in a solution that has been tested for sterility.

[0269] Dosage regimens in the above methods of treatment and uses are adjusted to provide the optimum desired response (eg, therapeutic response). For example, a single bolus may be administered, several divided doses may be administered over time or the dose may be proportionally increased or decreased as indicated by the exigencies of the therapeutic situation. Parenteral compositions can be formulated in dosage unit form for ease of administration and uniformity of dosage.

[0270] Effective dosages and dosage regimens of multispecific antibodies and fragments depend on the disease and condition to be treated and can be determined by one of ordinary knowledge in the art. An exemplary, non-limiting range of a therapeutically effective amount of a compound of the invention is about 0.001 to 10 mg / kg, such as about 0.001 to 5 mg / kg, for example about 0.001 to 2 mg / kg, such as about 0.001 to 1 mg / kg, For example about 0.001, about 0.01, about 0.1, about 1 or about 10 mg / kg.

[0271] A physician, pharmacist, or veterinarian having ordinary knowledge in the art can readily determine and prescribe the effective amount of the pharmaceutical composition required. For example, the physician or veterinarian can start with dosage levels of the multispecific antibody or fragment employed in the pharmaceutical composition lower than that required to achieve the desired therapeutic effect, and gradually increase the dosage until the desired effect is achieved. In general, a suitable daily dosage of a multispecific antibody of the invention will be that amount of the compound which is the lowest dosage effective to produce a therapeutic effect. Administration can be, for example, parenteral, such as intravenous, intramuscular, intratumoral (eg, bone marrow), or subcutaneous. In one embodiment, the multispecific antibody or fragment may be administered by infusion in weekly doses calculated in mg / m2. Such doses may be based, for example, on the mg / kg doses provided above, and provided according to the formula: dose (mg / kg) x body weight (eg, 50 to 100 kg). This administration may be repeated eg 1 to 8 times, such as 3 to 5 times. The administration may be performed by continuous infusion over a period of 2 to 24 hours, such as 2 to 12 hours. In one embodiment, the multispecific antibody or fragment may be administered by slow continuous infusion over a long period of time, such as over 24 hours, to reduce toxic side effects.

[0272] In one embodiment, the multispecific antibody or fragment may be administered in weekly doses calculated to be given as fixed doses up to eight times, such as four to six times when given once a week. This regimen can be repeated one or more times as desired, for example after six or twelve months. Such fixed doses may be based, for example, on the mg / kg doses provided above, with a body weight estimate of 50 to 100 kg. The dose can be determined or adjusted by measuring the amount of the multispecific antibody of the present invention in the blood after administration, for example, by collecting a biological sample and using GPRC5D and / or targeting the multispecific antibody of the present invention Anti-idiotypic antibody to the antigen-binding arm of BCMA was used to measure.

[0273] In one embodiment, the multispecific antibody or fragment may be administered by maintenance therapy, such as, for example, once a week for a period of six months or longer.

[0274] Multispecific antibodies or fragments may also be administered prophylactically to reduce the risk of developing cancer, delay the onset of cancer progression events, and / or reduce the risk of recurrence when the cancer is in remission.

[0275] Multispecific antibodies and fragments thereof as described herein may also be administered in combination therapy, ie, in combination with other relevant therapeutic agents for the disease or condition being treated. Thus, in one embodiment, the antibody-containing drug is used in combination with one or more further therapeutic agents, such as chemotherapeutics, anti-CD38 agents, immunomodulatory imide drugs (IMiDs), immune checkpoint inhibitors, Immune costimulators, gamma secretase inhibitors, T cell enhancers (eg, IL-2 supplementation), or any combination thereof. In some embodiments, the further therapeutic agent is an anti-CD38 agent, such as an anti-CD38 antibody (eg, daratumuab). In some embodiments, the further therapeutic agent is an immunomodulatory imide drug (IMiD), such as lenalidomide and pomalidomide. In some embodiments, the further therapeutic agent is an immune checkpoint inhibitor, such as anti-PD-1 and anti-T cell immune receptor with Ig and ITIM domains (TIGIT). In some embodiments, the further therapeutic agent is an immune costimulator, such as an agent targeting CD137 (eg, a CD137 costimulatory bispecific antibody). In some embodiments, the other therapeutic agent is cytarabine, anthracycline, histamine dihydrochloride, or interleukin-2. Such combined administration can be performed simultaneously, separately, or sequentially (in any order). For simultaneous administration, the agents can be administered as one composition or as separate compositions, as appropriate.

[0276] In one embodiment, there is provided a method for treating a disorder involving cells expressing GPRC5D and / or BCMA in a subject, the method comprising administering to a subject in need thereof a therapeutically effective amount of a multispecific antibody or Fragments (such as the BCMA x GPRC5D x CD3 multispecific antibody described herein), and radiation therapy. In one embodiment, there is provided a method for treating or preventing cancer, the method comprising administering to a subject in need thereof a therapeutically effective amount of a multispecific antibody or fragment (such as BCMA x GPRC5D x CD as described herein) antibodies), and radiotherapy. Radiation therapy may include radiation exposure or associated administration of radiopharmaceuticals to patients. The source of radiation may be external or internal to the patient being treated (radiation therapy may be, for example, a form of external beam radiation therapy (EBRT) or brachytherapy (BT)). Radioactive elements that can be used to practice these methods include, for example, radium, cesium-137, iridium-192, arsium-241, gold-198, cobalt-57, copper-67, 鎝-99, iodine-123, iodine-131, actinium -225, and indium-111. set

[0277] Also provided herein are kits, eg, comprising said multispecific antibody or antigen-binding fragment thereof, and instructions for use of said antibody or fragment for killing a particular cell type. In a preferred embodiment, the multispecific antibody is a BCMA x GPRC5D x CD3 multispecific antibody as described herein, or a multispecific antigen-binding fragment thereof, and more preferably a BCMA x as described herein GPRC5D x CD3 trispecific antibody, or BCMA x GPRC5D x CD3 trispecific antigen-binding fragment thereof. The instructions may include instructions for using the multispecific antibody or antigen-binding fragment thereof in vitro, in vivo, or ex vivo.

[0278] Typically, the kit will have a compartment containing the multispecific antibody or antigen-binding fragment thereof. The multispecific antibodies or antigen-binding fragments thereof can be in lyophilized form, liquid form, or other forms that can be modified for inclusion in a kit. Kits may also contain additional elements necessary to practice the methods described in the instructions of the kit, such as sterile solutions for reconstituting the lyophilized powder, for mixing with the multispecific antibody or Additional agents for combinations of antigen-binding fragments thereof, and means to assist in administering the multispecific antibody or antigen-binding fragment thereof to a patient. diagnostic use

[0279] The multispecific antibodies and fragments described herein may also be used for diagnostic purposes. Accordingly, also provided are diagnostic compositions comprising multispecific antibodies or fragments as defined herein, and uses thereof. In a preferred embodiment, the multispecific antibody is a BCMA x GPRC5D x CD3 multispecific antibody as described herein, or a multispecific antigen-binding fragment thereof, and more preferably a BCMA x as described herein GPRC5D x CD3 trispecific antibody, or BCMA x GPRC5D x CD3 trispecific antigen-binding fragment thereof. In one embodiment, the present invention provides a kit for diagnosing cancer, comprising a container comprising a BCMA x GPRC5D x CD3 trispecific antibody, and one or more antibodies for detecting the effect of the antibody on GPRC5D and / or BCMA-binding reagents. Reagents can include, for example, fluorescent tags, enzyme tags, or other detectable tags. The reagents may also include secondary or tertiary antibodies or reagents for enzymatic reactions that produce products that can be visualized. For example, the multispecific antibodies described herein, or antigen-binding fragments thereof, can be labeled with radioactivity, fluorescent labels, epitope tags, biotin, chromophore labels, ECL labels, enzymes, ruthenium, In -DOTA, 111In-diethylenetriaminepentaacetic acid (DTPA), horseradish peroxidase (horseradish peroxidase), alkaline phosphatase and β-galactosidase, or poly-histidine or those familiar in the field It is known that similar to these marks to be marked. BCMA specific antibody

[0280] Described herein are isolated antibodies and antigen-binding fragments specific for BCMA. In some embodiments, the BCMA-specific antibodies and antigen-binding fragments bind human BCMA. The general structure of a BCMA-specific antibody molecule can include an antigen binding domain, which includes a heavy chain and a light chain; and an Fc domain, which has various functions, including complement fixation and binding to antibody receptors.

[0281] In some embodiments there is provided a BCMA-specific antibody, or antigen-binding fragment thereof, comprising a heavy chain comprising CDR1, CDR2, CDR1, CDR2, and CDR3. In some embodiments there is provided a BCMA-specific antibody, or an antigen-binding fragment thereof, comprising a heavy chain comprising CDR1 of any one of the antibodies described in Table 1 (e.g., BCMB519), and a light chain, CDR2, and CDR3, the light chain comprising CDR1, CDR2, and CDR3 of any one of the antibodies described in Table 1 (eg, BCMB519).

[0282] In some embodiments, the BCMA-specific antibody, or antigen-binding fragment thereof, comprises: a heavy chain CDR1 comprising SEQ ID NO: 20, a heavy chain CDR2 comprising SEQ ID NO: 21, and a heavy chain comprising SEQ ID NO: 22 heavy chain CDR3. In some embodiments, the BCMA binding arm comprises: heavy chain CDR1 comprising SEQ ID NO: 20, heavy chain CDR2 comprising SEQ ID NO: 21, heavy chain CDR3 comprising SEQ ID NO: 22, comprising SEQ ID NO: The light chain CDR1 of 17, the light chain CDR2 comprising SEQ ID NO: 18, and the light chain CDR3 comprising SEQ ID NO: 19. The BCMA binding arm can comprise human framework sequences. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 24. In some embodiments, the BCMA binding arm comprises a heavy chain variable domain substantially identical to or identical to SEQ ID NO: 24 and a light chain variable domain substantially identical to or identical to SEQ ID NO: 23. The heavy and light chain variable domains of the antibodies discussed in this paragraph are suitable for inclusion in multispecific (e.g., bispecific or trispecific) constructs in which one arm is anti-BCMA arm. Exemplary trispecific constructs comprising the BCMA-specific antibodies or antigen-binding fragments thereof discussed in this paragraph are provided herein.

[0283] In some embodiments, the BCMA-specific antibodies and antigen-binding fragments bind human BCMA and cynomolgus monkey BCMA. In some embodiments, the BCMA-specific antibodies and antigen-binding fragments bind human BCMA but do not bind to cynomolgus monkey BCMA. In some embodiments, the BCMA-specific antibodies and antigen-binding fragments bind to an epitope comprising one or more residues from the BCMA extracellular domain (ECD). In some embodiments, the BCMA-specific antibody or antigen-binding fragment binds to residues 17 to 26 of the BCMA BCMW37 chain (LLHACIPCQL (SEQ ID NO: 162)). The BCMA-specific antibody or antigen-binding fragment may be 5x10-7M or lower (such as 1x10-7M or lower, 5x10-8M or lower, 1x10-8M or lower, 5x10-9M or lower, 1x10-9M or lower, or 5x10-10M or lower) affinity to BCMA. In one embodiment, the BCMA-specific antibody or antigen-binding fragment binds to BCMA with an affinity of about 1 x 10-10M to 1 x 10-9M. In one embodiment, the BCMA binding arm is at about 1 x 10-10M, about 2 x 10-10M, about 3 x 10-10M, about 4 x 10-10M, about 5 x 10-10M, about 6 x 10-10M, about 7 x 10 Binds to the BCMA with an affinity of -10M, about 8x10-10M, about 9x10-10M, or about 1x10-9M. In one embodiment, the BCMA-specific antibody or antigen-binding fragment binds to BCMA with an affinity of about 8.4 x 10-10 M as determined by surface plasmon resonance (SPR) assay. In one embodiment, the BCMA-specific antibody or antigen-binding fragment binds to BCMA with an affinity of about 2.1 x 10-10 M as determined by surface plasmon resonance (SPR) assay.

[0284] The IgG class is divided into four isotypes in humans: IgGl, IgG2, IgG3 and IgG4. The amino acid sequences of their Fc regions share more than 95% homology, but the amino acid composition and structure of the hinge region show major differences. The Fc region mediates effector functions such as antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). In ADCC, the Fc region of an antibody binds to Fc receptors (FcγRs) on the surface of immune effector cells, such as natural killer cells and macrophages, resulting in phagocytosis or lysis of target cells. In CDC, antibodies kill target cells by triggering the complement cascade on the cell surface. Antibodies described herein include antibodies having such variable domain properties in combination with any IgG isotype, including modified versions in which the Fc sequence has been modified to render different effector functions.

[0285] In many therapeutic antibody applications, Fc-mediated effector functions are not part of the mechanism of action. Effector functions of these Fc mediators may be deleterious and may pose a safety risk by causing off-mechanism toxicity. Modification of effector functions can be achieved by engineering the Fc region to reduce its binding to FcyRs or complement factors. IgG binding to activating (FcyRI, FcyRIIa, FcyRIIIa, and FcyRIIIb) and inhibitory (FcyRIIb) FcyRs or the first component of complement (C1q) depends on residues located in the hinge region and the CH2 domain. Mutations have been introduced into IgGl, IgG2 and IgG4 to reduce or silence Fc functionality. The antibodies described herein may include such modifications.

[0286] In one embodiment, the antibody comprises an Fc region that has one or more of the following properties: (a) reduced effector function when compared to a parental Fc; (b) for FcyRI, FcyRIIa, FcyRIIb, FcyRIIIb, and / or have reduced affinity for FcyRIIIa, (c) reduced affinity for FcyRI, (d) reduced affinity for FcyRIIa, (e) reduced affinity for FcyRIIb, (f) reduced affinity for FcyRIIIb, or (g) reduced affinity for FcyRIIIa affinity is reduced.

[0287] In some embodiments, the antibodies or antigen-binding fragments are IgG, or derivatives thereof, such as IgGl, IgG2, IgG3, and IgG4 isotypes. In some embodiments where the antibody has an IgG1 isotype, the antibody contains a L234A, L235A, D265S, and / or K409R substitution in the Fc region. In some embodiments where the antibody has an IgG4 isotype, the antibody contains K409R, S228P, L234A, and L235A substitutions in the Fc region. The antibodies described herein may include such modifications.

[0288] In some embodiments, the antibodies may be capable of inhibiting APRIL binding with a low nanomolar IC50 as determined by ELISA. In some embodiments, the antibodies may be capable of inhibiting BAFF binding with a low nanomolar IC50 as determined by ELISA.

[0289] In some embodiments, the antibody binds to a BCMA-positive multiple myeloma cell line.

[0290] In addition to the BCMA-specific antibodies and antigen-binding fragments, polynucleotide sequences encoding the antibodies and antigen-binding fragments are also provided. Also provided are vectors comprising such polynucleotides, such as cells expressing a BCMA-specific antibody or antigen-binding fragment provided herein. Cells capable of expressing the disclosed vectors are also described. Such cells may be mammalian cells (such as 293 cells, 293F cells, CHO cells), insect cells (such as Sf7 cells), yeast cells, plant cells, or bacterial cells (such as E. coli). The antibodies can also be produced by fusion of tumor cells.

[0291] The BCMA-specific antibodies or antigen-binding fragments include synthetic multimers of all isotypes (IgA, IgD, IgE, IgG, and IgM), and four-chain immunoglobulin structures. The antibodies or antigen-binding fragments also include the IgY isotype normally found in hen or turkey serum and hen or turkey egg yolk.

[0292] BCMA-specific antibodies and antigen-binding fragments can be derived from any species by recombinant means. For example, the antibodies or antigen-binding fragments can be chimeric versions of mouse, rat, goat, horse, pig, cow, chicken, rabbit, camel, donkey, llama, human, or the like. For administration to humans, non-human derived antibodies or antigen-binding fragments may be genetically or structurally modified to be less antigenic when administered to a human patient.

[0293] In some embodiments, the antibodies or antigen-binding fragments are chimeric. The term "chimeric" as used herein refers to an antibody, or antigen-binding fragment thereof, having at least some of at least one variable domain derived from an antibody amino acid sequence of a non-human mammal, rodent, or reptile. and the remainder of the antibody, or antigen-binding fragment thereof, is derived from humans.

[0294] In some embodiments, the antibodies are humanized antibodies. Humanized antibodies may be chimeric immunoglobulins, immunoglobulin chains or fragments thereof (such as Fv, Fab, Fab', F(ab')2, or other antigenic antigens of antibodies) containing minimal sequence derived from non-human immunoglobulins. combine subsequences). In general, humanized antibodies are human immunoglobulins (recipient antibodies) in which residues from the complementarity determining regions (CDRs) of the recipient are modified from proteins having the desired specificity, affinity, and capacity. Substitution of residues in CDRs of non-human species (donor antibody) such as mouse, rat or rabbit. In general, the humanized antibody will comprise substantially all of at least one and typically two variable domains, in which all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin, and in all or substantially all of the framework regions It is the framework region of human immunoglobulin sequence. A humanized antibody can comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin.

[0295] The antibodies or antigen-binding fragments described herein may be in a variety of forms, but will include one or more of the antibody CDRs shown in Table 1 (eg, BCMB519).

[0296] Described herein are recombinant antibodies and antigen-binding fragments that bind to BCMA. In some embodiments, the BCMA-specific antibodies or antigen-binding fragments are human IgG, or derivatives thereof. Although the BCMA-specific antibodies or antigen-binding fragments exemplified herein are human antibodies or antigen-binding fragments, the exemplified antibodies or antigen-binding fragments can be chimerized.

[0297] In some embodiments, the antibodies or antigen-binding fragments are IgG, or derivatives thereof, such as IgGl, IgG2, IgG3, and IgG4 isotypes. In some embodiments of the antibody is of the IgGl isotype, the antibody comprises an IgGl Fc region (SEQ ID NO: 158). SEQ ID NO: 158 ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNA KTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK

[0298] In some embodiments of the IgGl isotype of the antibody, the antibody comprises L234A, L235A, and D265S substitutions (underlined) in the Fc region of the antibody (SEQ ID NO: 159). SEQ ID NO: 159 ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPEAAGGPSVFLFPPKPKDTLMISRTPEVTCVVVSVSHEDPEVKFNWYVDGVEVHNAK TKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK

[0299] In some embodiments of the IgG4 isotype of the antibody, the antibody contains S228P, L234A, and L235A substitutions (underlined) in the Fc region of the antibody (SEQ ID NO: 160). SEQ ID NO: 160 ASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVESKYGPPCPPCPAPEAAGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPR EEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK

[0300] The BCMA-specific antibodies defined by the CDR and / or variable domain sequences discussed in the paragraph above may comprise these IgG Fc regions.

[0301] Isolated synthetic polynucleotides encoding such antibodies or antigen-binding fragments that bind to BCMA are also disclosed. The isolated polynucleotides capable of encoding the variable domain segments provided herein can be included on the same (or different) vectors to produce antibodies or antigen-binding fragments.

[0302] Polynucleotides encoding recombinant antigen binding proteins are also within the scope of the present disclosure. In some embodiments, the polynucleotides (and the peptides they encode) include a leader sequence. Any preamble sequence known in the art can be used. A leader sequence may include, but is not limited to, a restriction site or a translation start site.

[0303] The BCMA-specific antibodies or antigen-binding fragments described herein include variants having single or multiple amino acid substitutions, deletions, or additions that retain the PSMA-specific antibody or antigen binding Biological properties of the fragment (eg, binding affinity or immune effector activity). In the context of the present invention, the following notations are used to describe mutations, unless otherwise indicated; i) substitution of an amino acid in a specified position is written, for example, K409R, which represents the substitution of arginine for a lysine in position 409; and ii) use of specific three or one letter codes (including codes Xaa and X) to designate any amino acid residue in a particular variant. Thus, substitution of arginine for a lysine in position 409 is designated: K409R, or substitution of any amino acid residue for a lysine in position 409 is designated K409X. In case the lysine in position 409 is deleted, it is indicated with K409*. Variants having single or multiple amino acid substitutions, deletions, or additions can be produced by those with ordinary knowledge.

[0304] Such variants may include: (a) variants in which one or more amino acid residues are substituted with conservative or non-conservative amino acids, (b) variants in which one or more amino acid residues are added to Polypeptides or variants deleted from polypeptides, (c) variants in which one or more amino acids include substituents, and (d) variants in which the polypeptide is fused to another peptide or polypeptide (such as a fusion partner, protein tag, or other Chemical moieties that can confer useful properties on polypeptides, such as, for example, variants fused to epitopes of antibodies, polyhistidine sequences, biotin moieties, and the like). The antibodies or antigen-binding fragments described herein may include variants in which amino acid residues at conserved or non-reserved positions from one species are substituted with corresponding residues from another species. In other embodiments, amino acid residues at non-conservative positions are substituted with conservative or non-conservative residues. Techniques for obtaining such variants, including genetic (deletion, mutation, etc.), chemical, and enzymatic techniques, are known to those of ordinary skill in the art.

[0305] The BCMA-specific antibodies or antigen-binding fragments described herein may embody several antibody isotypes, such as IgM, IgD, IgG, IgA, and IgE. In some embodiments, the antibody is of IgG1, IgG2, IgG3, or IgG4 isotype, preferably IgG1 or IgG4 isotype. The specificity of an antibody or antigen-binding fragment thereof is largely determined by the amino acid sequence and arrangement of the CDRs. Thus, the CDRs of one isotype can be transferred to another without changing antigen specificity. Alternatively, techniques have been established to isotype-switch fusionomas from producing one antibody to another (isotype-switching) without altering antigen specificity. Accordingly, such antibody isotypes are within the scope of such antibodies or antigen-binding fragments.

[0306] The BCMA-specific antibodies or antigen-binding fragments described herein may have low nanomolar IC50 values ​​for APRIL binding. The IC50 of the BCMA-specific antibody or antigen-binding fragment can be determined by various methods known in the art, such as ELISA-based methods or flow cytometry (FACS). Assays to measure IC50 by ELISA with plate-bound BCMA and the presence and absence of BCMA-specific antibodies, and using various concentrations of APRIL. A BCMA antibody that blocks the binding of APRIL to BCMA "blocks APRIL as measured by ELISA".

[0307] Also provided are vectors comprising the polynucleotides described herein. These vectors can be expression vectors. Recombinant expression vectors containing sequences encoding polypeptides of interest are thus contemplated to be within the scope of the present disclosure. The expression vector may contain one or more additional sequences, such as, but not limited to, regulatory sequences (eg, promoters, enhancers), selectable markers, and polyadenylation signals. Vector systems for transforming a wide variety of host cells are well known and include, but are not limited to, plastids, phagemids, cosmids, baculoviruses, bacmids, artificial bacteria Chromosome (BAC), Artificial Yeast Chromosome (YAC), and other bacterial, yeast, and viral vectors.

[0308] Recombinant expression vectors within the scope of this embodiment include synthetic, genomic, or cDNA-derived nucleic acid segments encoding at least one recombinant protein operably linked to appropriate regulatory elements. Such regulatory elements may include transcriptional promoters, sequences encoding suitable mRNA ribosomal binding sites, and sequences that control termination of transcription and translation. Expression vectors, especially mammalian expression vectors, may also include one or more non-transcribed elements, such as an origin of replication, a suitable promoter and enhancer linked to the gene to be expressed, other 5' or 3' flanking non-transcribed elements. sequence, 5' or 3' untranslated sequences (such as necessary ribosome binding sites), polyadenylation sites, splice donor and acceptor sites, or transcription termination sequences. An origin of replication that confers the ability to replicate in the host may also be incorporated.

[0309] Transcriptional and translational control sequences in expression vectors for transformation of vertebrate cells may be provided by viral sources. Exemplary vectors can be constructed as described in Okayama and Berg, 3 Mol. Cell. Biol. 280 (1983).

[0310] In some embodiments, the antibody coding sequence or antigen-binding fragment coding sequence is placed under the control of a strong constitutive promoter, such as the promoters of the following genes: hypoxanthine phosphoribosyltransferase (HPRT), adenine Glycoside deaminase, pyruvate kinase, β-actin, human myosin, human heme, human muscle creatine, and others. In addition, many viral promoters function constitutively in eukaryotic cells and are suitable for use with the described examples. Such viral promoters include but are not limited to cytomegalovirus (CMV) immediate early promoter, SV40 early and late promoters, mouse mammary tumor virus (MMTV) promoter, Moloney leukemia virus (Maloney leukemia virus) Chest of long terminal repeat (LTR), human immunodeficiency virus (HIV), Epstein-Barr virus (EBV), Rous sarcoma virus (RSV), and other retroviruses, and Herpes Simplex Virus Glycoside kinase promoter. In one embodiment, the BCMA-specific antibody or antigen-binding fragment coding sequence is placed under the control of an inducible promoter, such as metallothionein promoter, tetracycline-inducible promoter, doxycycline (doxycycline) Inducible promoters, promoters containing one or more interferon stimulus response elements (ISREs), such as protein kinase R 2',5'-oligoadenylate synthase, Mx gene, ADAR1, and the like.

[0311] The vectors described herein may contain one or more internal ribosome entry sites (IRES). Incorporation of IRES sequences into fusion vectors can be beneficial in enhancing the expression of some proteins. In some embodiments, the vector system will include one or more polyadenylation sites (eg, SV40), which may be upstream or downstream of any of the foregoing nucleic acid sequences. Vector components may be linked adjacently, or arranged in a manner that provides optimal spacing for expression of the gene product (i.e., by introducing "spacer" nucleotides between ORFs), or otherwise place. Regulatory elements such as IRES motifs can also be arranged to provide optimal spacing for performance.

[0312] Such vectors may contain selectable markers, which are well known in the art. Selectable markers include positive and negative selectable markers, such as antibiotic resistance genes (e.g. neomycin resistance gene, hygromycin resistance gene, kanamycin resistance gene, tetracycline resistance gene, Penicillin resistance gene, puromycin (puromycin) resistance gene, blasticidin (blasticidin) resistance gene), glutamate synthase gene, HSV-TK, for ganciclovir (ganciclovir) selection HSV-TK derivatives, or the bacterial purine nucleoside phosphorylase gene for 6-methylpurine selection (Gadi et al., 7 Gene Ther. 1738-1743 (2000)). The nucleic acid sequence encoding the selectable marker or the cloning site can be upstream or downstream of the nucleic acid sequence encoding the polypeptide of interest or the cloning site.

[0313] The vectors described herein can be used to transform various cells with the gene encoding the antibody or antigen-binding fragment. For example, vectors can be used to produce BCMA-specific antibody or antigen-binding fragment producing cells. Accordingly, another aspect features a host cell transformed with a vector comprising a nucleic acid sequence encoding an antibody or antigen-binding fragment thereof that binds BCMA, such as the antibodies or antigen-binding fragments described and exemplified herein.

[0314] Many techniques for introducing foreign genes into cells are known in the art and can be used to construct recombinant cells for carrying out the methods described and exemplified herein. The technique used should provide stable transfer of the heterologous gene sequence to the host cell so that the heterologous gene sequence can be inherited and expressed by the progeny of the cell without interference with the essential developmental and physiological functions of the recipient cell. Techniques that may be used include, but are not limited to, chromosomal transfer (e.g., cell fusion, chromosome-mediated gene transfer, microcell-mediated gene transfer), physical methods (e.g., transfection, spheroplast fusion, microinjection, electroporation). perforation, liposome vehicles), viral vector transfer (eg, recombinant DNA viruses, recombinant RNA viruses) and the like (described in Cline, 29 Pharmac. Ther. 69-92 (1985)). Calcium phosphate precipitation and polyethylene glycol (PEG)-induced fusion of bacterial protoplasts with mammalian cells can also be used to transform cells.

[0315] Cells suitable for expressing BCMA-specific antibodies or antigen-binding fragments described herein are preferably eukaryotic cells, more preferably cells derived from plants, rodents, or humans, such as but not limited to NSO, CHO, CHOK1, perC.6, Tk-ts13, BHK, HEK293 cells, COS-7, T98G, CV-1 / EBNA, L cells, C127, 3T3, HeLa, NS1, Sp2 / 0 myeloma cells, and BHK cells department, and others. In addition, antibody expression can be achieved using fusionoma cells. Methods for producing fusionomas are well established in the art.

[0316] Cells transformed with the expression vectors described herein can be selected or screened for recombinant expression of the antibodies or antigen-binding fragments described herein. Recombination-positive cells are expanded and screened for subclones exhibiting a desired phenotype, such as high expression levels, enhanced growth properties, or production, e.g., due to protein modifications or modified post-translational The ability to modify a protein to have desired biochemical characteristics. These phenotypes may be due to intrinsic properties of a given subclonal or due to mutations. Mutations can be achieved through the use of chemicals, UV wavelength light, radiation, viruses, insertional mutagens, inhibition of DNA mismatch repair, or a combination of these methods. Treatment using BCMA-specific antibodies

[0317] Provided herein are BCMA-specific antibodies or antigen-binding fragments thereof for use in therapy. In particular, these antibodies or antigen-binding fragments are useful in the treatment of cancer, such as BCMA manifest cancers, or other BCMA manifest disorders. Accordingly, the invention provides a method of treating cancer comprising administering an antibody as described herein, such as a BCMA-specific antibody or antigen-binding fragment. For example, the use may be by interfering with BCMA-receptor interactions, or wherein the antibody is conjugated to the toxin, thereby targeting the toxin to the BCMA expressing cancer. In some embodiments, the BCMA manifest cancer or disorder comprises lymphoma, such as multiple myeloma (MM), including smoldering multiple myeloma (SMM), or amyloidosis, plasma cell leukemia, and lupus. In some embodiments, the BCMA expressing cancer is a relapsed or refractory form of lymphoma, such as a relapsed or refractory form of multiple myeloma. Antibodies useful in these methods include those described above, such as BCMA having the characteristics described in Table 1 (e.g., BCMB519) (e.g., CDR or variable domain sequences) and in the further discussion of these antibodies Specific antibodies or antigen-binding fragments.

[0318] In some embodiments described herein, the immune effector properties of the BCMA-specific antibodies can be determined by Fc assays by techniques known to those of ordinary skill in the art or described herein. Modifications to reinforce or silence. For example, Fc effector functions such as C1q binding, complement-dependent cytotoxicity (CDC), antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cell-mediated phagocytosis (ADCP), downregulation of cell surface receptors (eg B cell receptor; BCR) etc.) can be provided and / or controlled by modifying the residues in Fc responsible for these activities.

[0319] "Antibody-dependent cell-mediated cytotoxicity (antibody-dependent cell-mediated cytotoxicity)" or "ADCC" refers to a cell-mediated response in which non-specific cytotoxic cells (such as natural Killer (NK) cells, neutrophils, and macrophages) recognize bound antibodies on target cells and cause target cell lysis.

[0320] The ability of monoclonal antibodies to induce ADCC can be enhanced by engineering their oligosaccharide components. Human IgGl or IgG3 are N-glycosylated at Asn297 and most glycans are in the well known biantennary G0, G0F, Gl, GlF, G2 or G2F forms. Antibodies produced by unengineered CHO cells generally have a glycan fucose content of about at least 85%. Removal of core fucose from the biantennary complex oligosaccharide attached to the Fc region enhanced ADCC of the antibody by improving FcγRIIIa binding without altering antigen binding or CDC activity. Such mAbs can be achieved using different approaches that have been reported to result in the successful expression of relatively high amounts of defucosylated antibodies (Fc oligosaccharides with biantennary complexes), such as controlled culture osmolarity (Konno et al. al., Cytotechnology 64:249-65, 2012), the variant CHO line Lec13 was used as the host cell line (Shields et al., J Biol Chem 277:26733-26740, 2002), the variant CHO line EB66 was used as the host cell (Olivier et al., MAbs; 2(4), 2010; electronic release prior to paper publication; PMID: 20562582), using the rat fusion tumor cell line YB2 / 0 as the host cell line (Shinkawa et al., J Biol Chem 278:3466-3473, 2003), the introduction of small interfering RNA specific for the α1,6-fucosyltransferase (FUT8) gene (Mori et al., Biotechnol Bioeng 88:901-908, 2004), or Coexpresses β-1,4-N-acetylglucosaminyltransferase III with Gorgiella α-mannosidase II or the potent α-mannosidase I inhibitor kifunensine (Ferrara et al., J Biol Chem 281:5032-5036, 2006, Ferrara et al., Biotechnol Bioeng 93:851-861, 2006; Xhou et al., Biotechnol Bioeng 99:652-65, 2008).

[0321] In some embodiments described herein, ADCC induced by BCMA antibodies can also be enhanced by certain substitutions in the antibody Fc. Exemplary substitutions are, for example, substitutions at amino acid positions 256, 290, 298, 312, 356, 330, 333, 334, 360, 378, or 430 (residue numbering is according to the EU index), as described in U.S. Pat. No. 6,737,056. Methods of Detecting BCMA

[0322] Provided herein are methods for detecting BCMA in a biological sample by contacting the sample with an antibody described herein, or an antigen-binding fragment thereof. As described herein, the sample can be derived from urine, blood, serum, plasma, saliva, ascitic fluid, circulating cells, circulating tumor cells, cells that are not tissue-associated (i.e., free cells), tissue (e.g., surgically resected Tumor tissue, biopsies including fine needle aspiration), tissue samples, and the like. In some embodiments, the methods comprise detecting BCMA in a biological sample by contacting the sample with any of the BCMA-specific antibodies described herein, or antigen-binding fragments thereof.

[0323] In some embodiments, the sample can be contacted with more than one BCMA-specific antibody or antigen-binding fragment described herein. For example, a sample can be contacted with a first BCMA-specific antibody, or antigen-binding fragment thereof, followed by contact with a second BCMA-specific antibody, or antigen-binding fragment thereof, wherein the first antibody or antigen-binding fragment is in contact with the second An antibody or antigen-binding fragment is not the same antibody or antigen-binding fragment. In some embodiments, the primary antibody, or antigen-binding fragment thereof, can be immobilized to a surface (such as a multi-well disc, wafer, or similar substrate) prior to contacting the sample. In other embodiments, the first antibody, or antigen-binding fragment thereof, may not be immobilized (or attached) to anything at all prior to contacting the sample.

[0324] The BCMA-specific antibodies and antigen-binding fragments can be detectably labeled. In some embodiments, labeled antibodies and antigen-binding fragments facilitate detection of BCMA by the methods described herein. Many such markers are known to those of ordinary skill in the art. For example, suitable labels include, but should not be considered limited to, radioactive labels, fluorescent labels, epitope tags, biotin, chromophore labels, ECL labels, or enzymes. More specifically, the markers include ruthenium, 111In-DOTA, 111In-diethylenetriaminepentaacetic acid (DTPA), horseradish peroxidase, alkaline phosphatase and β-galactosidase, polyhistidine ( HIS tag), acridine dyes, cyanine dyes, fluorone dyes, (oxazin) dyes, pyridine dyes, rose bengal dyes, Alexafluor® dyes, and the like.

[0325] The BCMA-specific antibodies and antigen-binding fragments can be used in a variety of assays to detect BCMA in biological samples. Some suitable assays include, but should not be considered limited to, western blotting, radioimmunoassay, surface plasmon resonance, immunofluorescence, immunoprecipitation, equilibrium dialysis, immunodiffusion, electrochemiluminescence ( ECL) immunoassay, immunohistochemistry, fluorescence activated cell sorting (FACS) or ELISA assay.

[0326] In some embodiments described herein, detection of BCMA expressing cancer cells in a subject can be used to determine that the subject can be treated with a therapeutic agent directed against BCMA.

[0327] BCMA was present at detectable levels in blood and serum samples. Accordingly, provided herein are methods for detecting BCMA in a blood-derived sample, such as a serum sample, by contacting the sample with an antibody or antigen-binding fragment thereof that binds BCMA. The blood sample or derivative thereof can be diluted, aliquoted, or otherwise processed to yield a sample on which the methods can be performed. In some embodiments, BCMA can be detected in blood samples or derivatives thereof by many assays known in the art, such as (but not limited to) western blot analysis, radioimmunoassay, surface plasmon resonance , immunofluorescence, immunoprecipitation, equilibrium dialysis, immunodiffusion, electrochemiluminescence (ECL) immunoassay, immunohistochemistry, fluorescence activated cell sorting (FACS) or ELISA assay. In some embodiments, the method is an in vitro method. Method for diagnosing cancer or disorder

[0328] Provided herein are methods for diagnosing a BCMA expressing cancer or disorder in a subject. In some embodiments, the BCMA manifest cancer or disorder includes lymphomas, such as multiple myeloma (MM), including smoldering multiple myeloma (SMM), or amyloidosis, plasma cell leukemia, and lupus. In some embodiments, detection of BCMA in a biological sample, such as a blood sample or a serum sample, provides the ability to diagnose cancer in a subject from which the sample was obtained, as described above. Alternatively, in some embodiments, other samples (such as tissue samples, fine needle aspiration samples, resected tumor tissue, circulating cells, circulating tumor cells, and the like) may also be used to assess whether the subject (from whom the sample was obtained) has have cancer. In some embodiments, the subject (from whom the sample was obtained) may have been known to have cancer, but the type of cancer the subject has may not have been diagnosed or a preliminary diagnosis may not be known, so detection of The presence of BCMA in a biological sample may enable or clarify the diagnosis of the cancer. For example, it may be known that a subject has cancer, but it may not be known or clear whether the subject's cancer is BCMA expressive.

[0329] In some embodiments, the methods involve assessing whether a subject has a BCMA expressing cancer or disorder by determining the amount of BCMA present in a biological sample derived from the subject; and comparing the observed BCMA Amount and the amount of BCMA in a control (or reference) sample, wherein a difference in the amount of BCMA in a sample derived from the subject and the amount of BCMA in the control (or reference) sample indicates that the subject suffers from a BCMA expressing cancer or disorder. In another embodiment, the amount of BCMA observed in a biological sample obtained from a subject can be compared to BCMA levels known to be associated with certain forms or stages of cancer to determine the form or stage of cancer in the subject . In some embodiments, the amount of BCMA in a sample derived from the subject is assessed by contacting the sample with an antibody that binds BCMA, or an antigen-binding fragment thereof, such as a BCMA-specific antibody described herein. Samples for the assessment of the presence of BCMA can be derived from urine, blood, serum, plasma, saliva, ascitic fluid, circulating cells, circulating tumor cells, cells not associated with tissues (i.e., free cells), tissues (e.g., surgically resected Tumor tissue, biopsies including fine needle aspiration), tissue samples, and the like. In some embodiments, the BCMA expressing cancer or disorder includes hematological cancers, such as multiple myeloma (MM), including smoldering multiple myeloma (SMM), or amyloidosis, plasma cell leukemia, and lupus. In some embodiments, the BCMA expressing cancer is a relapsed or refractory form of lymphoma, such as a relapsed or refractory form of multiple myeloma. In some embodiments, the subject is a human.

[0330] In some embodiments, the method of diagnosing a BCMA-expressing cancer or disorder will involve: subjecting a biological sample to a BCMA-specific antibody, or antigen-binding fragment thereof (such as may be derived from the antibodies and fragments provided in Table 1 (e.g., BCMB519)); quantifying the amount of BCMA present in the sample and bound by the antibody or antigen-binding fragment thereof; comparing the amount of BCMA present in the sample to a known standard or reference sample; and used to It is determined whether the subject's BCMA level falls within a BCMA level associated with a cancer or disorder. In additional embodiments, the diagnostic method may be followed by the additional step of administering or prescribing a BCMA-specific therapy. In another embodiment, the diagnostic method may be followed by an additional step of communicating the determination to facilitate treatment of the cancer or disorder. In some embodiments, the BCMA-specific therapy may be directed against a BCMA expressing cancer or disorder, such as a BCMA x CD3 multispecific antibody described herein.

[0331] In some embodiments, the methods involve assessing whether a subject has a BCMA expressing cancer or disorder by determining the amount of BCMA present in a blood or serum sample obtained from the subject; and comparing the observed and the amount of BCMA in a control (or reference) sample, wherein a difference in the amount of BCMA in a sample derived from the subject and the amount of BCMA in the control (or reference) sample indicates that the subject suffers from a BCMA-expressing cancer or disorder.

[0332] In some embodiments, the control (or reference) sample can be derived from a subject not suffering from a BCMA expressing cancer or disorder. In some embodiments, the control (or reference) sample can be derived from a subject suffering from a BCMA expressing cancer or disorder. In some embodiments where the control (or reference) sample is derived from a subject not suffering from a BCMA expressing cancer or disorder, the amount of BCMA present in the test sample is observed relative to the amount observed in the control or reference sample An increase, indicating that the subject is suffering from a BCMA expressing cancer or condition. In some embodiments where the control sample is derived from a subject not suffering from a BCMA expressing cancer or disorder, a reduced or similar amount of BCMA present in the test sample is observed relative to the amount observed in the control or reference sample, Indicates that the subject being assessed does not suffer from a BCMA manifest cancer or condition. In some embodiments where the control or reference sample is derived from a subject suffering from a BCMA expressing cancer or disorder, it is observed that the amount of BCMA present in the test sample is similar to the amount observed in the control or reference sample, indicating The subject is suffering from a BCMA manifest cancer or disorder. In some embodiments where the control or reference sample is derived from a subject suffering from a BCMA expressing cancer or disorder, a decrease in the amount of BCMA present in the test sample relative to the amount observed in the control or reference sample is observed, indicating The subject being evaluated does not have a BCMA manifest cancer or condition.

[0333] In some embodiments, the amount of BCMA in a sample derived from the subject is assessed by contacting the sample with an antibody, or antigen-binding fragment thereof, that binds BCMA, such as an antibody described herein. Samples for the assessment of the presence of BCMA can be derived from blood samples, serum samples, circulating cells, circulating tumor cells, cells not associated with tissues (i.e. episomal cells), tissues (e.g. surgically resected tumor tissue, biopsies including fine needle aspiration), tissue samples, and the like.

[0334] In various aspects, the amount of BCMA is determined by contacting a sample with an antibody, or antigen-binding fragment thereof, that binds BCMA. In some embodiments, a sample can be contacted with more than one type of BCMA-binding antibody, or antigen-binding fragment thereof. In some embodiments, the sample can be contacted with a first antibody, or antigen-binding fragment thereof, that binds BCMA, followed by contact with a second antibody, or antigen-binding fragment thereof, that binds BCMA. BCMA-specific antibodies or antigen-binding fragments such as those described herein can be used in this method.

[0335] Various combinations of BCMA-specific antibodies and antigen-binding fragments can be used to provide "first" and "second" antibodies or antigen-binding fragments for carrying out the diagnostic methods described. In some embodiments, the BCMA expressing cancer or disorder comprises lymphoma, such as multiple myeloma (MM), including smoldering multiple myeloma (SMM). In some embodiments, the BCMA expressing cancer is a relapsed or refractory form of lymphoma, such as a relapsed or refractory form of multiple myeloma.

[0336] In certain embodiments, the amount of BCMA is determined by the following methods: western blot analysis, radioimmunoassay, immunofluorescence, immunoprecipitation, equilibrium dialysis, immunodiffusion, electrochemiluminescence (ECL ) immunoassay, immunohistochemistry, fluorescence activated cell sorting (FACS) or ELISA assay.

[0337] In various embodiments of the diagnostic methods, a control or reference sample is used. This sample can be used as a positive or negative assay control to ensure the correct functioning of the assay used; for example, assay controls of this nature may be commonly used in immunohistochemistry assays. Alternatively, the sample can be a standard reference for the amount of BCMA used in a biological sample from a healthy subject. In some embodiments, the observed level of BCMA in a subject can be compared to the observed level of BCMA in a sample from a subject known to have a BCMA expressing cancer or disorder. In some embodiments, the control subject may suffer from the particular cancer or condition of interest. In some embodiments, the control subject is known to have an early stage cancer, which may or may not be a BCMA expressing cancer. In some embodiments, the control subject is known to have an intermediate stage cancer, which may or may not be a BCMA expressing cancer. In some embodiments, the control subject is known to have advanced cancer, which may or may not be a BCMA expressing cancer.

[0338] In some embodiments, the method for diagnosing a cancer or disorder is an in vitro method. Method for monitoring cancer or disorder

[0339] Provided herein are methods for monitoring a BCMA expressing cancer or disorder in a subject. In some embodiments, the BCMA manifest cancer or disorder includes lymphomas, such as multiple myeloma (MM), including smoldering multiple myeloma (SMM), or amyloidosis, plasma cell leukemia, and lupus. In some embodiments, the BCMA expressing cancer is a relapsed or refractory form of lymphoma, such as a relapsed or refractory form of multiple myeloma. In some embodiments, the methods involve assessing whether a BCMA expressing cancer or condition is progressing, regressing, or remaining stable by determining the amount of BCMA present in a test sample derived from the subject; and comparing the observed The amount of BCMA received and the amount of BCMA obtained in a biological sample from the subject in a similar manner at an earlier time point, wherein the difference between the amount of BCMA in the test sample and the earlier sample provides whether the cancer is progressing, Indication of fading, or remaining stable. In this regard, an increase in the amount of BCMA in a test sample relative to the amount observed in earlier samples may indicate the progression of a BCMA expressing cancer or disorder. Conversely, a decrease in the amount of BCMA in a test sample relative to that observed in earlier samples may indicate regression of a BCMA expressing cancer or disorder.

[0340] Thus, a non-significant difference in the amount of BCMA in a test sample relative to that observed in an earlier sample may indicate a stable disease state for a BCMA expressing cancer or disorder. In some embodiments, the amount of BCMA in a biological sample derived from the subject is assessed by contacting the sample with an antibody, or antibody fragment thereof, that binds BCMA, such as an antibody described herein. Samples for the assessment of the presence of BCMA may be derived from urine, blood, serum, plasma, saliva, ascitic fluid, circulating cells, circulating tumor cells, cells not associated with tissue (i.e., free cells), tissue (e.g., surgically resected tumor tissue, biopsy (including fine needle aspiration), tissue specimens, and the like. In some embodiments, the subject is a human.

[0341] In some embodiments, the method of monitoring a BCMA expressing cancer or disorder will involve: subjecting a biological sample to a BCMA-specific antibody, or antigen-binding fragment thereof (such as may be derived from the antibodies and fragments provided in Table 1 (e.g., BCMB519)); quantify the amount of BCMA present in the sample; compare the amount of BCMA present in the sample to the amount of BCMA determined in a biological sample obtained in the same manner from the same subject at an earlier time point and determining whether the subject's BCMA level has changed over time. An increase in the amount of BCMA in a test sample relative to that observed in earlier samples may be indicative of cancer progression. Conversely, a decrease in the amount of BCMA in a test sample relative to that observed in earlier samples may indicate regression of a BCMA expressing cancer or disorder. Therefore, a non-significant difference in the amount of BCMA in a test sample relative to that observed in an earlier sample may indicate a stable disease state for a BCMA expressing cancer or disorder. In some embodiments, the level of BCMA in a sample can be compared to a known standard or reference sample alone, or otherwise compared to the level of BCMA observed in a sample assessed at an earlier time point. In additional embodiments, the diagnostic method may be followed by the additional step of administering a BCMA-specific therapy. In some embodiments, a BCMA-specific therapy may be directed against a BCMA expressing cancer or disorder, such as a BCMA x CD3 multispecific antibody described herein.

[0342] In various aspects, the amount of BCMA is determined by contacting a sample with an antibody, or antigen-binding fragment thereof, that binds BCMA. In some embodiments, a sample can be contacted with more than one type of BCMA-binding antibody, or antigen-binding fragment thereof. In some embodiments, the sample can be contacted with a first antibody, or antigen-binding fragment thereof, that binds BCMA, followed by contact with a second antibody, or antigen-binding fragment thereof, that binds BCMA. Antibodies such as those described herein can be used in this method.

[0343] Various combinations of the antibodies and antigen-binding fragments described in Table 1 can be used to provide "first" and "second" antibodies or antigen-binding fragments for carrying out the monitoring methods described. In some embodiments, the BCMA expressing cancer or disorder comprises a hematological cancer, such as acute myelogenous leukemia (AML) or lymphoma (e.g., multiple myeloma (MM), smoldering multiple myeloma (SMM), Or amyloidosis, plasma cell leukemia, and lupus.

[0344] In certain embodiments, the amount of BCMA is determined by the following methods: western blot analysis, radioimmunoassay, immunofluorescence, immunoprecipitation, equilibrium dialysis, immunodiffusion, electrochemiluminescence (ECL ) immunoassay, immunohistochemistry, fluorescence activated cell sorting (FACS) or ELISA assay. In some embodiments, the method is an in vitro method. Kit for detecting BCMA

[0345] Provided herein are kits for the detection of BCMA in biological samples. These kits include one or more BCMA-specific antibodies, or antigen-binding fragments thereof, described herein, and instructions for use of the kit.

[0346] Provided BCMA-specific antibodies or antigen-binding fragments can be in solution; lyophilized; immobilized to a substrate, carrier, or plate; or detectably labeled.

[0347] The kits may also include additional components useful for performing the methods described herein. For example, such kits may include means for obtaining a sample from a subject, a control or reference sample (such as a sample from a subject with slowly progressive cancer and / or a subject without cancer), one or more Sample compartments, and / or instructional material describing the performance of the methods of the invention and the organization of specific controls or standards.

[0348] The means for determining BCMA levels may further include, for example, buffers or other reagents in assays for determining BCMA levels. These instructions may be, for example, printed instructions for administering the test and / or instructions for assessing BCMA performance levels.

[0349] The kit may also include means for isolating samples from the subject. These means may comprise one or more items of equipment or reagents from which fluid or tissue can be obtained from the subject. Means for obtaining a sample from a subject may also include means for isolating blood components, such as serum, from a blood sample. Preferably, the kit is designed for use in human subjects. Example

[0350] The disclosure provided herein also provides the following non-limiting examples. Embodiment 1. A trispecific antibody or a trispecific binding fragment thereof, comprising: (a) a first antigen-binding arm comprising a first heavy chain variable domain (VH1) and a first light chain variable domain (VL1); (b) a second antigen binding arm comprising a second heavy chain variable domain (VH2) and a second light chain variable domain (VL2); (c) a third antigen binding arm comprising a third A heavy chain variable domain (VH3) and a third light chain variable domain (VL3), wherein the first antigen-binding arm binds to an epitope on cluster of differentiation 3 (CD3), and the second antigen-binding arm binds to a G protein is coupled to an epitope on receptor family C group 5 member D (GPRC5D), and the third antigen binding arm binds to an epitope on B cell maturation antigen (BCMA). Embodiment 2. The trispecific antibody or trispecific binding fragment as described in embodiment 1, wherein the VH1 and VL1 of the first antigen-binding arm are present in the diabody, Fab, Fab', F(ab')2 , Fv, scFv, Fd, disulfide-stabilized Fv fragment (dsFv), or disulfide-stabilized diabody (ds diabody), optionally present in a Fab. Embodiment 3. The trispecific antibody or trispecific binding fragment as described in embodiment 1 or 2, wherein the VH2 and VL2 of the second antigen binding arm are present in the diabody, Fab, Fab', F(ab ')2, Fv, scFv, Fv, Fd, disulfide stabilized Fv fragment (dsFv), or disulfide stabilized diabody (ds diabody), optionally present in scFv. Embodiment 4. The trispecific antibody or trispecific binding fragment as described in any one of embodiments 1 to 3, wherein the VH3 and VL3 of the third antigen-binding arm are present in an antibody fragment, a diabody, a Fab , Fab', F(ab')2, Fv, scFv, Fd, disulfide-stabilized Fv fragment (dsFv), or disulfide-stabilized diabody (ds diabody), optionally present in scFv. Embodiment 5. The trispecific antibody or trispecific binding fragment of any one of embodiments 1 to 4, wherein the first antigen binding arm that binds CD3 comprises the heavy chain variable of SEQ ID NO: 8 The heavy chain complementarity determining region (HCDR) 1, HCDR2, and HCDR3 of domain (VH1) and the light chain complementarity determining region (LCDR) 1, LCDR2, and LCDR3 of the light chain variable domain (VL1) of SEQ ID NO: 7 . Embodiment 6. The trispecific antibody or trispecific binding fragment of any one of embodiments 1 to 5, wherein the first antigen-binding arm that binds CD3 comprises: comprising GDSVFNNNAAWS (SEQ ID NO: 4) HCDR1 comprising the amino acid sequence, HCDR2 comprising the amino acid sequence of RTYYRSKWLYD (SEQ ID NO: 5), and HCDR3 comprising the amino acid sequence of GYSSSFDY (SEQ ID NO: 6); and comprising TGTSSNIGTYKFVS (SEQ ID NO: 1) LCDR1 comprising the amino acid sequence of EVSKRPS (SEQ ID NO: 2), LCDR2 comprising the amino acid sequence of VSYAGSGTLL (SEQ ID NO: 3), and LCDR3 comprising the amino acid sequence of VSYAGSGTLL (SEQ ID NO: 3). Embodiment 7. The trispecific antibody or trispecific binding fragment of any one of embodiments 1 to 6, wherein the first antigen-binding arm that binds CD3 comprises the VH1 of SEQ ID NO: 8 and SEQ ID NO: The VL1 of 7. Embodiment 8. The trispecific antibody or trispecific binding fragment of any one of embodiments 1 to 7, wherein the second antigen binding arm that binds GPRC5D comprises the heavy chain variable of SEQ ID NO: 16 The heavy chain complementarity determining region (HCDR) 1, HCDR2, and HCDR3 of the heavy chain domain (VH2) and the light chain complementarity determining region (LCDR) 1, LCDR2, and LCDR3 of the light chain variable domain (VL2) of SEQ ID NO: 15 . Embodiment 9. The trispecific antibody or trispecific binding fragment of any one of embodiments 1 to 8, wherein the second antigen binding arm that binds GPRC5D comprises: comprising GFSLTNIRMSVS (SEQ ID NO: 12) HCDR1 comprising the amino acid sequence, HCDR2 comprising the amino acid sequence of HIFSNDEKS (SEQ ID NO: 13), and HCDR3 comprising the amino acid sequence of MRLPYGMDV (SEQ ID NO: 14); and comprising RSSQSLVHSDGNTYLS (SEQ ID NO: 9), LCDR1 comprising the amino acid sequence of KISNRFF (SEQ ID NO: 10), LCDR2 comprising the amino acid sequence of MQATQFPHT (SEQ ID NO: 11), and LCDR3 comprising the amino acid sequence of MQATQFPHT (SEQ ID NO: 11). Embodiment 10. The trispecific antibody or trispecific binding fragment of any one of embodiments 1 to 9, wherein the second antigen binding arm that binds GPRC5D comprises the VH2 of SEQ ID NO: 16 and SEQ ID NO: 15 of the VL2. Embodiment 11. The trispecific antibody or trispecific binding fragment of any one of embodiments 1 to 10, wherein the third antigen binding arm that binds BCMA comprises the heavy chain variable of SEQ ID NO: 24 The heavy chain complementarity determining region (HCDR) 1, HCDR2, and HCDR3 of the heavy chain domain (VH3) and the light chain complementarity determining region (LCDR) 1, LCDR2, and LCDR3 of the light chain variable domain (VL3) of SEQ ID NO: 23 . Embodiment 12. The trispecific antibody or trispecific binding fragment of any one of embodiments 1 to 11, wherein the third antigen binding arm that binds BCMA comprises: comprising GFTFSSYAMS (SEQ ID NO: 20) HCDR1 comprising the amino acid sequence, HCDR2 comprising the amino acid sequence of AISGSGGSTY (SEQ ID NO: 21), and HCDR3 comprising the amino acid sequence of DEGYSSGHYYGMDV (SEQ ID NO: 22); and comprising RASQSISSSFLT (SEQ ID NO: 17), LCDR1 comprising the amino acid sequence of GASSRAT (SEQ ID NO: 18), LCDR2 comprising the amino acid sequence of GASSRAT (SEQ ID NO: 18), and LCDR3 comprising the amino acid sequence of QHYGSSPMYT (SEQ ID NO: 19). Embodiment 13. The trispecific antibody or trispecific binding fragment of any one of embodiments 1 to 12, wherein the third antigen binding arm that binds BCMA comprises the VH3 of SEQ ID NO: 24 and SEQ ID NO: The VL3 of 23. Embodiment 14. The trispecific antibody or trispecific binding fragment as described in any one of embodiments 1 to 4, wherein the first antigen-binding arm that binds CD3 comprises HCDR1, HCDR1 of the VH1 of SEQ ID NO: 8 HCDR2, and HCDR3, and LCDR1, LCDR2, and LCDR3 of the VL1 of SEQ ID NO: 7; the second antigen-binding arm that binds to GPRC5D comprises HCDR1, HCDR2, and HCDR3 of the VH2 of SEQ ID NO: 16, and SEQ ID NO LCDR1, LCDR2, and LCDR3 of the VL2 of : 15; and the third antigen-binding arm that binds BCMA comprises HCDR1, HCDR2, and HCDR3 of the VH3 of SEQ ID NO: 24 and LCDR1 of the VL3 of SEQ ID NO: 23 , LCDR2, and LCDR3. Embodiment 15. The trispecific antibody or trispecific binding fragment of any one of embodiments 1 to 4 and 14, wherein the first antigen-binding arm that binds CD3 comprises SEQ ID NO: 4, 5, respectively , HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of 6, 1, 2, and 3. The second antigen binding arm that binds GPRC5D comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOS: 12, 13, 14, 9, 10, and 11, respectively; and binds the third antigen to BCMA The binding arms comprise HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NO: 20, 21, 22, 17, 18, and 19, respectively. Embodiment 16. The trispecific antibody or trispecific binding fragment of any one of embodiments 1-4, 14, and 15, wherein the first antigen-binding arm that binds CD3 comprises SEQ ID NO: 8 The VH1 and the VL1 of SEQ ID NO:7. The second antigen-binding arm that binds GPRC5D comprises the VH2 of SEQ ID NO: 16 and the VL2 of SEQ ID NO: 15; and the third antigen-binding arm that binds BCMA comprises the VH3 of SEQ ID NO: 24 and SEQ ID The VL3 of NO: 23; Embodiment 17. The trispecific antibody or its trispecific binding fragment as described in any one of embodiments 1 to 16, the first antigen-binding arm comprises a crystallizable fragment (Fc) domain , and the second antigen-binding arm or the third antigen-binding arm comprises an Fc domain. Embodiment 18. The trispecific antibody or trispecific binding fragment thereof of embodiment 17, wherein the Fc domains comprise one or more mutations that promote heterodimerization of the Fc domains. Embodiment 19. The trispecific antibody or trispecific binding fragment of embodiment 18, wherein the mutation is selected from T366S, L368A, T366W, and Y407V (EU numbering). Embodiment 20. The trispecific antibody or trispecific binding fragment of any one of embodiments 17-19, wherein the Fc domains further comprise one or more mutations that reduce Fc binding to Fcγ receptors. Embodiment 21. The trispecific antibody or trispecific binding fragment as described in embodiment 20, wherein the Fcγ receptor is FcyRI, FcyRIIA, FcyRIIB, FcyRIIIA, and / or FcyRIIIB. Embodiment 22. The trispecific antibody or trispecific binding fragment as described in embodiment 20 or 21, wherein the Fc domains comprise one or more mutations selected from L234A, L235A, and D265S (EU numbering). Embodiment 23. The trispecific antibody or trispecific binding fragment of any one of embodiments 17-22, wherein the Fc domains further comprise one or more mutations that reduce Fc binding to Protein A. Embodiment 24. The trispecific antibody or trispecific binding fragment of embodiment 23, wherein the Fc domain comprises mutations H435R and / or Y436F (EU numbering). Embodiment 25. The trispecific antibody or trispecific binding fragment of any one of embodiments 1 to 24, wherein the first antigen binding arm specifically binds to residues 22 to 35 of the CD3ε chain (QDGNEEMGGITQTP (SEQ ID NO: 161)). Embodiment 26. The trispecific antibody or trispecific binding fragment of any one of embodiments 1 to 25, wherein the first antigen binding arm is specific with an affinity of about 1×10-8 to 1×10-7M Binds to CD3. Embodiment 27. The trispecific antibody or trispecific binding fragment of embodiment 26, wherein the first antigen binding arm specifically binds to CD3 with an affinity of about 2×10-8 to 4×10-8M. Embodiment 28. The trispecific antibody or trispecific binding fragment of any one of embodiments 1 to 27, wherein the third antigen binding arm specifically binds residues 17 to 26 of the BCMA BCMW37 chain (LLHACIPCQL( SEQ ID NO: 162)). Embodiment 29. The trispecific antibody or trispecific binding fragment of any one of embodiments 1 to 28, wherein the third antigen binding arm is specific with an affinity of about 1 x 10-10 to 1 x 10-7M Sexual binding to BCMA. Embodiment 30. The trispecific antibody or trispecific binding fragment of embodiment 29, wherein the third antigen binding arm specifically binds to BCMA with an affinity of about 2×10-10 to 9×10-10M.Example 31. A trispecific antibody or trispecific binding fragment comprising a first antigen-binding arm that binds to an epitope on cluster of differentiation 3 (CD3), binds to G protein-coupled receptor family C5 A second antigen-binding arm to an epitope on group member D (GPRC5D), and a third antigen-binding arm to an epitope on B-cell maturation antigen (BCMA), wherein the first antigen-binding arm comprises a heavy chain (HC1 ) polypeptide and a light chain (LC) polypeptide; and wherein the trispecific antibody or trispecific binding fragment thereof comprises a single polypeptide comprising the second antigen-binding arm and the third antigen-binding arm. Embodiment 32. The trispecific antibody or trispecific binding fragment of embodiment 31, wherein the HC1 of the first antigen-binding arm comprises the amino acid sequence of SEQ ID NO: 26. Embodiment 33. The trispecific antibody or trispecific binding fragment of embodiment 32, wherein the LC of the first antigen-binding arm comprises the amino acid sequence of SEQ ID NO: 27. Embodiment 34. The trispecific antibody or trispecific binding fragment of embodiment 32 or 33, wherein the polypeptide comprising the second antigen binding arm and the third antigen binding arm comprises the amine of SEQ ID NO: 28 amino acid sequence. Embodiment 35. The trispecific antibody or trispecific binding fragment of embodiment 31, wherein the first antigen binding arm comprises: HCl comprising the amino acid sequence of SEQ ID NO: 26, and comprising SEQ ID NO LC of the amino acid sequence of SEQ ID NO: 27, and the polypeptide comprising the second antigen-binding arm and the third antigen-binding arm comprises the amino acid sequence of SEQ ID NO: 28. Example 36. A trispecific antibody or trispecific binding fragment comprising a first antigen-binding arm that binds to an epitope on cluster of differentiation 3 (CD3), binds to G protein-coupled receptor family C5 A second antigen-binding arm to an epitope on group member D (GPRC5D), and a third antigen-binding arm to an epitope on B-cell maturation antigen (BCMA), wherein the first antigen-binding arm comprises a heavy chain (HC1 ) polypeptide and a light chain (LC) polypeptide, wherein the heavy chain (HC1) polypeptide further comprises the second antigen binding arm, wherein the trispecific antibody or trispecific binding fragment thereof further comprises a single polypeptide comprising the Third antigen binding arm. Embodiment 37. The trispecific antibody or trispecific binding fragment of embodiment 36, wherein the HC1 of the first antigen-binding arm comprises the amino acid sequence of SEQ ID NO: 29. Embodiment 38. The trispecific antibody or trispecific binding fragment of embodiment 36 or 37, wherein the LC of the first antigen-binding arm comprises the amino acid sequence of SEQ ID NO: 30. Embodiment 39. The trispecific antibody or trispecific binding fragment of any one of embodiments 36-38, wherein the single polypeptide comprising the third antigen binding arm comprises the amino acid of SEQ ID NO: 31 sequence. Embodiment 40. The trispecific antibody or trispecific binding fragment of embodiment 36, wherein the first antigen binding arm comprises: HCl comprising the amino acid sequence of SEQ ID NO: 29, and comprising SEQ ID NO LC of the amino acid sequence of SEQ ID NO: 30, and the single polypeptide comprising the third antigen-binding arm comprises the amino acid sequence of SEQ ID NO: 31. Embodiment 41. The trispecific antibody or trispecific binding fragment of any one of embodiments 1-40, wherein the antibody or antigen-binding fragment thereof is of the IgGl, IgG2, IgG3, or IgG4 isotype. Embodiment 42. The trispecific antibody or trispecific binding fragment of any one of embodiments 1-41, wherein the antibody or antigen-binding fragment thereof is of the IgGl isotype. Embodiment 43. A synthetic polynucleotide encoding the trispecific antibody or trispecific binding fragment of any one of embodiments 1-42. Embodiment 44. A pharmaceutical composition comprising the trispecific antibody or trispecific binding fragment as described in any one of embodiments 1-42 and a pharmaceutically acceptable carrier. Embodiment 45. The pharmaceutical composition of embodiment 44, wherein the pharmaceutical composition further comprises a second therapeutic agent. Embodiment 46. The pharmaceutical composition as described in embodiment 45, wherein the second therapeutic agent comprises anti-CD38 agent, immunomodulatory imide drug (IMiD), immune checkpoint inhibitor, immune costimulator, gamma secretase Inhibitors, T cell enhancers, or any combination thereof. Embodiment 47. A cell expressing the trispecific antibody or trispecific binding fragment of any one of embodiments 1-42. Embodiment 48. The cell of embodiment 47, wherein the cell line is a fusionoma. Embodiment 49. The cell of embodiment 47, wherein the trispecific antibody is recombinantly produced. Embodiment 50. A method for treating cancer in a subject in need thereof, the method comprising administering to the subject a therapeutically effective amount of the trispecific antibody or trispecific antibody of any one of embodiments 1-42 A sex-binding fragment or a pharmaceutical composition as described in any one of embodiments 43-46. Embodiment 51. The method of embodiment 50, wherein the trispecific antibody or trispecific binding fragment or the pharmaceutical composition is administered for a time sufficient to treat the cancer. Embodiment 52. A method for inhibiting the growth or proliferation of cancer cells, the method comprising administering to the cell an effective amount of the trispecific antibody or trispecific binding agent as described in any one of embodiments 1-42 Fragments or the pharmaceutical composition as described in any one of embodiments 43 to 46, wherein the effective amount is sufficient to inhibit the growth or proliferation of the cancer cells. Embodiment 53. The method of embodiment 52, wherein the cancer cell line is in a subject and the trispecific antibody or trispecific binding fragment or the pharmaceutical composition is administered to the subject. Embodiment 54. The method of Embodiment 52, wherein the administering is performed ex vivo. Embodiment 55. A method of redirecting T cells in a subject in need to BCMA and / or GPRC5D expressing cancer cells, the method comprising administering to the subject a therapeutically effective amount of any one of embodiments 1-42 A trispecific antibody or a trispecific binding fragment thereof or a pharmaceutical composition as in any one of embodiments 43-46. Embodiment 56. The method of embodiment 55, wherein the therapeutically effective amount is sufficient to direct the T cell response to the cancer cells. Embodiment 57. The method of any one of embodiments 50-56, wherein the cancer is a hematological cancer. Embodiment 58. The method of embodiment 57, wherein the hematological cancer is BCMA and / or GPRC5D expressing B cell cancer. Embodiment 59. The method of embodiment 58, wherein the BCMA and / or GPRC5D expressing B cell cancer is multiple myeloma. Embodiment 60. The method of embodiment 59, wherein the BCMA and / or GPRC5D expressing B cell carcinoma is smoldering multiple myeloma (SMM). Embodiment 61. The method of any one of embodiments 50-60, wherein the cancer is recurrent, refractory, or malignant cancer, or any combination thereof. Embodiment 62. The method of any one of embodiments 50-51, 53, and 55-61, wherein the subject has received previous treatment. Embodiment 63. The method of embodiment 62, the prior therapy comprising a proteasome inhibitor, an immunomodulatory drug, a CD38 antibody, a bispecific agent, a CAR-T therapy, or a combination thereof. Embodiment 64. The method of any one of preceding Embodiments 50-63, further comprising administering a second therapeutic agent. Embodiment 65. The method of embodiment 64, wherein the second therapeutic agent is a chemotherapeutic agent or a targeted anticancer therapy. Embodiment 66. The method of embodiment 65, wherein the chemotherapeutic agent is cytarabine, anthracycline, histamine dihydrochloride, or interleukin 2 (IL-2). Embodiment 67. The method of embodiment 64, wherein the second therapeutic agent is an anti-CD38 agent, an immunomodulatory imide drug (IMiD), an immune checkpoint inhibitor, an immune costimulator, a gamma secretase inhibitor , a T cell enhancer, or any combination thereof. Embodiment 68. The method of any one of embodiments 50-51, 53, and 55-67, wherein the trispecific antibody or trispecific binding fragment, or the pharmaceutical composition is administered intravenously, intramuscularly The subject is administered intraperitoneally, intraperitoneally, and / or subcutaneously. Embodiment 69. The method of any one of embodiments 50-51, 53, and 55-68, wherein the trispecific antibody or trispecific binding fragment, or the pharmaceutical composition is administered subcutaneously to the object. Embodiment 70. A method for producing the trispecific antibody or trispecific binding fragment of any one of embodiments 1-42, wherein the method comprises culturing any one of embodiments 47-49 The cells are used to isolate the trispecific antibody or trispecific binding fragment. Embodiment 71. A kit comprising (i) the trispecific antibody or trispecific binding fragment as described in any one of embodiments 1 to 42 and / or the polynucleotide as described in embodiment 43 and (ii) its packaging. Embodiment 72. An antibody or antigen-binding fragment thereof that binds to BCMA, comprising: heavy chain complementarity determining region 1 (CDR1) having the amino acid sequence of GFTFSSYAMS (SEQ ID NO: 20), having AISGSGGSTY (SEQ ID The heavy chain CDR2 having the amino acid sequence of NO: 21), and the heavy chain CDR3 having the amino acid sequence of DEGYSSGHYYGMDV (SEQ ID NO: 22). Embodiment 73. The antibody or antigen-binding fragment according to embodiment 72, which further comprises: light chain complementarity determining region 1 (CDR1) having the amino acid sequence of RASQSISSSFLT (SEQ ID NO: 17), having GASSRAT (SEQ ID NO: 17) : 18) of the light chain CDR2 amino acid sequence, and the light chain CDR3 having the amino acid sequence of QHYGSSPMYT (SEQ ID NO: 19). Embodiment 74. The antibody or antigen-binding fragment of embodiment 72 or 73, which comprises a heavy chain variable domain (VH) having the amino acid sequence of SEQ ID NO: 24. Embodiment 75. The antibody or antigen-binding fragment of any one of embodiments 72-74, comprising a light chain variable domain (VL) having the amino acid sequence of SEQ ID NO: 23. Embodiment 76. The antibody or antigen-binding fragment of any one of embodiments 72-75, wherein the antibody or antigen-binding fragment specifically binds residues 17 to 26 of the BCMA BCMW37 chain (LLHACIPCQL (SEQ ID NO: 162 )). Embodiment 77. The antibody or antigen-binding fragment of any one of embodiments 72-76, wherein the antibody or antigen-binding fragment specifically binds to BCMA with an affinity of about 1 x 10-10 to 1 x 10-7M. Embodiment 78. The antibody or antigen-binding fragment of embodiment 77, wherein the antibody or antigen-binding fragment specifically binds to BCMA with an affinity of about 2×10-10 to 9×10-10M. Embodiment 79. The antibody or antigen-binding fragment of any one of embodiments 72-78, wherein the antibody or antigen-binding fragment is a human antibody or antigen-binding fragment. Embodiment 80. The antibody or antigen-binding fragment of any one of embodiments 72-79, wherein the antibody or antigen-binding fragment is recombinant. Embodiment 81. The antigen-binding fragment of any one of embodiments 72-80, wherein the antigen-binding fragment is a Fab fragment, a Fab2 fragment, or a single chain antibody. Embodiment 82. The antibody or antigen-binding fragment of any one of embodiments 72-81, wherein the antibody or antigen-binding fragment thereof is of the IgGl, IgG2, IgG3, or IgG4 isotype. Embodiment 83. The antibody or antigen-binding fragment of any one of embodiments 72-82, wherein the antibody or antigen-binding fragment thereof is of the IgGl or IgG4 isotype. Embodiment 84. A pharmaceutical composition comprising the antibody or antigen-binding fragment of any one of embodiments 72-83 and a pharmaceutically acceptable carrier. Embodiment 85. The pharmaceutical composition of embodiment 84, wherein the pharmaceutical composition further comprises a second therapeutic agent. Embodiment 86. The pharmaceutical composition of embodiment 85, wherein the second therapeutic agent comprises an anti-CD38 agent, an immunomodulatory imide drug (IMiD), an immune checkpoint inhibitor, an immune co-stimulator, gamma secretase Inhibitors, T cell enhancers, or any combination thereof. Embodiment 87. A cell expressing the antibody or antigen-binding fragment of any one of embodiments 72-83. Embodiment 88. The cell of embodiment 87, wherein the cell line is a fusionoma. Embodiment 89. The cell of embodiment 87, wherein the antibody is recombinantly produced.Embodiment 90. A method for treating cancer in a subject in need thereof, the method comprising administering to the subject a therapeutically effective amount of the antibody or antigen-binding fragment of any one of embodiments 72-83 or as described in The pharmaceutical composition of any one of Examples 84-86. Embodiment 91. The method of embodiment 90, wherein the antibody or antigen-binding fragment or the pharmaceutical composition is administered for a time sufficient to treat the cancer. Embodiment 92. A method for inhibiting the growth or proliferation of cancer cells, the method comprising administering to the cell an effective amount of the antibody or antigen-binding fragment as described in any one of embodiments 72-83 or as described in embodiment The pharmaceutical composition according to any one of 84 to 86, wherein the effective amount is sufficient to inhibit the growth or proliferation of the cancer cells. Embodiment 93. The method of embodiment 92, wherein the cancer cell line is in a subject and the antibody or antigen-binding fragment or pharmaceutical composition is administered to the subject. Embodiment 94. The method of Embodiment 92, wherein the administering is performed ex vivo. Embodiment 95. The method of any one of embodiments 90-94, wherein the cancer is a hematological cancer. Embodiment 96. The method of embodiment 95, wherein the hematological cancer is BCMA expressing B cell carcinoma. Embodiment 97. The method of embodiment 96, wherein the BCMA expressing B cell carcinoma is multiple myeloma. Embodiment 98. The method of embodiment 97, wherein the BCMA expressing B cell carcinoma is smoldering multiple myeloma (SMM). Embodiment 99. The method of any one of embodiments 90 to 98, wherein the cancer is recurrent, refractory, or malignant cancer, or any combination thereof. Embodiment 100. The method of any one of embodiments 90-91, 93, and 95-99, wherein the subject has received previous treatment. Embodiment 101. The method of embodiment 100, the prior therapy comprising a proteasome inhibitor, an immunomodulatory drug, a CD38 antibody, a bispecific agent, CAR-T therapy, or a combination thereof. Embodiment 102. The method of any one of embodiments 90-101, further comprising administering a second therapeutic agent. Embodiment 103. The method of embodiment 102, wherein the second therapeutic agent is a chemotherapeutic agent or a targeted anticancer therapy. Embodiment 104. The method of Embodiment 103, wherein the chemotherapeutic agent is cytarabine, anthracycline, histamine dihydrochloride, or interleukin 2 (IL-2). Embodiment 105. The method of embodiment 104, wherein the second therapeutic agent is an anti-CD38 agent, an immunomodulatory imide drug (IMiD), an immune checkpoint inhibitor, an immune costimulator, a gamma secretase inhibitor , a T cell enhancer, or any combination thereof. Embodiment 106. The method of any one of embodiments 90-91, 93, and 95-105, wherein the antibody or antigen-binding fragment or pharmaceutical composition is administered intravenously, intramuscularly, intraperitoneally, and / or or subcutaneously administered to the subject. Embodiment 107. The method of any one of embodiments 90-91, 93, and 95-106, wherein the antibody or antigen-binding fragment, or the pharmaceutical composition is administered to the subject subcutaneously. Embodiment 108. A method for producing the antibody or antigen-binding fragment of any one of embodiments 72-83, wherein the method comprises culturing the cells of any one of embodiments 87-89 and singling from the antibody or antigen-binding fragment. Embodiment 109. A synthetic polynucleotide encoding the antibody or antigen-binding fragment of any one of embodiments 72-83. Embodiment 110. A kit comprising (i) the antibody or antigen-binding fragment of any one of embodiments 72-83 and / or the polynucleotide of embodiment 109 and (ii) its packaging. Embodiment 111. A trispecific antibody or trispecific binding fragment thereof comprising: a) a first heavy chain portion (HC1) comprising a first heavy chain variable domain (VH); b) a light chain portion (LC) comprising a light chain variable domain (VL); and c) a second heavy chain portion (HC2) comprising a second VH domain, wherein (i) the HC1 VH and the LC VL domain form a binding first a first antigen binding site for an antigen, (ii) the HC2 VH domain forms a second antigen binding site that binds a second antigen, (iii) the HC1 or the HC2 further comprises a third antigen binding site that binds a third antigen The third VH domain of point, (iv) each of the HC1 and HC2 optionally comprises a crystallizable fragment (Fc) domain comprising a CH2-CH3 domain; and wherein the first antigen is cluster of differentiation 3 (CD3 ), and (v) the second antigen is B cell maturation antigen (BCMA), and the third antigen is G protein-coupled receptor family C group 5 member D (GPRC5D); or (vi) the second antigen It is G protein-coupled receptor family C group 5 member D (GPRC5D), and the third antigen is B cell maturation antigen (BCMA). Embodiment 112. The trispecific antibody or trispecific binding fragment of embodiment 111, wherein the HC2 comprises the third VH domain that forms the third antigen binding site that binds the third antigen. Embodiment 113. The trispecific antibody or trispecific binding fragment of embodiment 112, wherein the HC2 comprises from N to C terminus the second VH domain forming the second antigen binding site, the Fc domain, A first linker (L1), and the third VH domain forming the third antigen combining site. Embodiment 114. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 113, wherein the HC2 comprises the second VH domain that forms the second antigen binding site that binds GPRC5D, And the HC2 further comprises the third VH domain forming the third antigen binding site that binds BCMA. Embodiment 115. The trispecific antibody or trispecific binding fragment of embodiment 111, wherein the HC1 comprises the third VH domain that forms the third antigen binding site that binds the third antigen. Embodiment 116. The trispecific antibody or trispecific binding fragment of embodiment 115, wherein the HCl comprises the first VH, CH1 domain, the Fc from N to C terminus forming the first antigen binding site domain, a first linker (L1), and the third VH domain forming the third antigen combining site. Embodiment 117. The trispecific antibody or trispecific binding fragment of any one of embodiments 111, 115, and 116, wherein the HC2 comprises the second VH domain that forms the second antigen binding site that binds BCMA , and the HC1 further comprises the third VH domain forming the third antigen-binding site binding to GPRC5D. Embodiment 118. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 117, wherein the HC1 VH and LC VL forming the first antigen binding site comprise an antigen binding fragment (Fab ), the antigen-binding fragment comprises the first antigen-binding site. Embodiment 119. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 118, wherein the HC2 VH forms a single chain variable fragment (scFv) comprising the second antigen binding site . Embodiment 120. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 119, wherein the third VH forms a single chain variable fragment (scFv) comprising the third antigen binding site ). Embodiment 121. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 120, wherein the Fc domains of HC1 and HC2 comprise one or more different mutations that promote heterodimerization . Embodiment 122. The trispecific antibody or trispecific binding fragment of embodiment 121, wherein the Fc domain of the HC1 comprises mutations T366S, L368A, and Y407V (EU numbering), and the Fc domain of the HC2 comprises Mutation T366W (EU number). Embodiment 123. The trispecific antibody or trispecific binding fragment of embodiment 121, wherein the Fc domain of the HC2 comprises mutations T366S, L368A, and Y407V (EU numbering), and the Fc domain of the HC1 comprises Mutation T366W (EU number). Embodiment 124. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 123, wherein the Fc domains of HC1 and / or HC2 further comprise one that reduces binding of Fc to Fcγ receptors or multiple mutations. Embodiment 125. The trispecific antibody or trispecific binding fragment of embodiment 124, wherein the Fcγ receptor is FcyRI, FcyRIIA, FcyRIIB, FcyRIIIA, and / or FcyRIIIB. Embodiment 126. The trispecific antibody or trispecific binding fragment of embodiment 124 or 125, wherein the Fc domains of HC1 and / or HC2 each comprise a protein selected from L234A, L235A, and D265S (EU numbering) one or more mutations. Embodiment 127. The trispecific antibody or trispecific binding fragment of embodiment 126, wherein the Fc domains of HC1 and HC2 each comprise mutations L234A, L235A, and D265S (EU numbering). Embodiment 128. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 127, wherein the Fc domains of HC1 or HC2 further comprise one or more of reducing Fc binding to Protein A mutation. Embodiment 129. The trispecific antibody or trispecific binding fragment of embodiment 128, wherein the Fc domains of HC1 or HC2 comprise mutations H435R and / or Y436F (EU numbering). Embodiment 130. The trispecific antibody or trispecific binding fragment of embodiment 129, wherein the Fc domain of HC1 comprises mutations H435R and Y436F (EU numbering). Embodiment 131. The trispecific antibody or trispecific binding fragment of any one of embodiments 113 to 114 and 116 to 130, wherein the first linker (L1 ) comprises SEQ ID NO: 25, 127 to Any one of the amino acid sequences of 157 and 163. Embodiment 132. The trispecific antibody or trispecific binding fragment of any one of embodiments 131, wherein the first linker (L1 ) comprises GGSEGKSSGSGSESKSTGGS (SEQ ID NO: 25) or GGGGSGGGGSGGGGSGGGGS ((G4S) 4, the amino acid sequence of SEQ ID NO: 163). Embodiment 133. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 132, wherein the first antigen binding site that binds CD3 comprises: comprising GDSVFNNNAAWS (SEQ ID NO: 4) The amino acid sequence of heavy chain complementarity determining region 1 (CDR1), the heavy chain CDR2 comprising the amino acid sequence of RTYYRSKWLYD (SEQ ID NO: 5), and the amino acid sequence comprising GYSSSFDY (SEQ ID NO: 6) The heavy chain CDR3. Embodiment 134. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 133, wherein the first antigen binding site that binds CD3 comprises: comprising TGTSSNIGTYKFVS (SEQ ID NO: 1 ) The amino acid sequence of light chain complementarity determining region 1 (CDR1), the light chain CDR2 comprising the amino acid sequence of EVSKRPS (SEQ ID NO: 2), and the amino acid sequence comprising VSYAGSGTLL (SEQ ID NO: 3) The light chain CDR3. Embodiment 135. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 134, wherein the first antigen binding site that binds CD3 comprises a heavy chain variable domain (VH), the The heavy chain variable domain contains the amino acid sequence of SEQ ID NO:8. Embodiment 136. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 135, wherein the first antigen binding site that binds CD3 comprises a light chain variable domain (VL), the The light chain variable domain comprises the amino acid sequence of SEQ ID NO:7. Embodiment 137. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 136, wherein the second or third antigen binding site that binds GPRC5D comprises: comprising GFSLTNIRMSVS (SEQ ID NO The heavy chain complementarity determining region 1 (CDR1) of the amino acid sequence of: 12), the heavy chain CDR2 of the amino acid sequence comprising HIFSNDEKS (SEQ ID NO: 13), and the amine comprising MRLPYGMDV (SEQ ID NO: 14) Amino acid sequence of heavy chain CDR3.Embodiment 138. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 137, wherein the second or third antigen binding site that binds GPRC5D comprises: comprising RSSQSLVHSDGNTYLS (SEQ ID NO : 9) the light chain complementarity determining region 1 (CDR1) of the amino acid sequence, the light chain CDR2 comprising the amino acid sequence of KISNRFF (SEQ ID NO: 10), and the amine comprising MQATQFPHT (SEQ ID NO: 11) Amino acid sequence of light chain CDR3. Embodiment 139. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 138, wherein the second or third antigen binding site that binds GPRC5D comprises: comprising SEQ ID NO: 16 The amino acid sequence of the heavy chain variable domain (VH). Embodiment 140. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 139, wherein the second or third antigen binding site that binds GPRC5D comprises: comprising SEQ ID NO: 15 The amino acid sequence of the light chain variable domain (VL). Embodiment 141. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 140, wherein the second or third antigen binding site that binds BCMA comprises: comprising GFTFSSYAMS (SEQ ID NO : 20) of the amino acid sequence of the heavy chain complementarity determining region 1 (CDR1), the heavy chain CDR2 comprising the amino acid sequence of AISGSGGSTY (SEQ ID NO: 21), and the amine comprising DEGYSSGHYYGMDV (SEQ ID NO: 22) Amino acid sequence of heavy chain CDR3. Embodiment 142. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 141, wherein the second or third antigen binding site that binds BCMA comprises: comprising RASQSISSSFLT (SEQ ID NO The light chain complementarity determining region 1 (CDR1) of the amino acid sequence of: 17), the light chain CDR2 of the amino acid sequence comprising GASSRAT (SEQ ID NO: 18), and the amine comprising QHYGSSPMYT (SEQ ID NO: 19) Amino acid sequence of light chain CDR3. Embodiment 143. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 142, wherein the second or third antigen binding site that binds BCMA comprises: comprising SEQ ID NO: 24 The amino acid sequence of the heavy chain variable domain (VH). Embodiment 144. The trispecific antibody or trispecific binding fragment of any one of embodiments 111 to 143, wherein the second or third antigen binding site that binds BCMA comprises: comprising SEQ ID NO: 23 The amino acid sequence of the light chain variable domain (VL). Embodiment 145. The trispecific antibody or trispecific binding fragment of any one of embodiments 119 to 144, wherein the scFv comprises VH, a second linker (L2), and VL ( VH-L2-VL); or VL, L2 and VH (VL-L2-VH). Embodiment 146. The trispecific antibody or trispecific binding fragment of any one of embodiments 119 to 145, wherein the scFv comprises the VL, the L2, and the VH (VL-L2 -VH). Embodiment 147. The trispecific antibody or trispecific binding fragment of embodiment 145 or 146, wherein the second linker (L2) comprises the amino acids of SEQ ID NO: 25, 127 to 157, and 163 any of the sequences. Embodiment 148. The trispecific antibody or trispecific binding fragment of any one of embodiments 145-147, wherein the L2 comprises the amino acid sequence of GGSEGKSSGSGSESKSTGGS (SEQ ID NO: 25). Embodiment 149. The antibody or antigen-binding fragment of any one of embodiments 111 to 148, wherein the first antigen binding site specifically binds to residues 22 to 35 of the CD3 epsilon chain (QDGNEEMGGITQTP (SEQ ID NO : 161)). Embodiment 150. The antibody or antigen-binding fragment of any one of embodiments 111 to 149, wherein the first antigen binding site specifically binds to CD3 with an affinity of about 1 x 10-8 to 1 x 10-7M. Embodiment 151. The antibody or antigen-binding fragment of embodiment 150, wherein the first antigen binding site specifically binds to CD3 with an affinity of about 2 x 10-8 to 4 x 10-8M. Embodiment 152. The antibody or antigen-binding fragment of any one of embodiments 111 to 151, wherein the second or third antigen binding site specifically binds residues 17 to 26 of the BCMA BCMW37 chain (LLHACIPCQL (SEQ ID NO: 162)). Embodiment 153. The antibody or antigen-binding fragment of embodiment 152, wherein the second or third antigen binding site specifically binds to BCMA with an affinity of about 1 x 10-10 to 1 x 10-7M. Embodiment 154. The antibody or antigen-binding fragment of embodiment 153, wherein the second or third antigen binding site specifically binds to BCMA with an affinity of about 2 x 10-10 to 9 x 10-10M. Embodiment 155. The antibody or antigen-binding fragment of any one of embodiments 111-154, wherein the antibody or antigen-binding fragment thereof is of the IgGl, IgG2, IgG3, or IgG4 isotype. Embodiment 156. The antibody or antigen-binding fragment of any one of embodiments 111-155, wherein the antibody or antigen-binding fragment thereof is of the IgGl isotype. Embodiment 157. The trispecific antibody or trispecific binding fragment of embodiment 111, wherein the HC1 comprises the amino acid sequence of SEQ ID NO: 26. Embodiment 158. The trispecific antibody or trispecific binding fragment of embodiment 111 or 157, wherein the LC comprises the amino acid sequence of SEQ ID NO: 27. Embodiment 159. The trispecific antibody or trispecific binding fragment of embodiment 111, 157, or 158, wherein the HC2 comprises the amino acid sequence of SEQ ID NO: 28. Embodiment 160. The trispecific antibody or trispecific binding fragment of embodiment 111, wherein the HCl comprises the amino acid sequence of SEQ ID NO: 29. Embodiment 161. The trispecific antibody or trispecific binding fragment of embodiment 111 or 160, wherein the LC comprises the amino acid sequence of SEQ ID NO: 30. Embodiment 162. The trispecific antibody or trispecific binding fragment of embodiment 111, 160, or 161, wherein the HC2 comprises the amino acid sequence of SEQ ID NO: 31.

[0351] The present invention may also be defined by the following numbered clauses. Clause 1. A trispecific antibody or trispecific binding fragment thereof comprising: a) a first heavy chain (HC1); b) a light chain (LC); and c) a second heavy chain (HC2), wherein (i) the HC1 and the LC form a first antigen binding site that specifically binds a first antigen, (ii) the HC2 comprises a second antigen binding site that specifically binds a second antigen, (iii) the HC1 or The HC2 further comprises a third antigen binding domain that specifically binds a third antigen, (iv) the HC1 and HC2 each comprise a fragment crystallizable (Fc) domain, the fragment crystallizable domain comprising a CH2-CH3 domain; and wherein the first the antigen is cluster of differentiation 3 (CD3), and (v) the second antigen is B cell maturation antigen (BCMA), and the third antigen is G protein-coupled receptor family C group 5 member D (GPRC5D); or (vi) The second antigen is G protein-coupled receptor family C group 5 member D (GPRC5D), and the third antigen is B cell maturation antigen (BCMA). Item 2. The trispecific antibody or trispecific binding fragment of Item 1, wherein the HC2 comprises the third antigen binding site that specifically binds the third antigen. Clause 3. The trispecific antibody or trispecific binding fragment of Clause 2, wherein the HC2 comprises the second antigen binding site, the Fc domain, a linker, and the third antigen binding site from N to C-terminus. Antigen binding site. Clause 4. The trispecific antibody or trispecific binding fragment of any one of Clauses 1 to 3, wherein the HC2 comprises a second antigen binding site that specifically binds GPRC5D, and the HC2 further comprises a specific Sexually binds to the third antigen-binding site of BCMA. Item 5. The trispecific antibody or trispecific binding fragment of Item 1, wherein the HCl comprises the third antigen binding site that specifically binds the third antigen. Clause 6. The trispecific antibody or trispecific binding fragment of clause 5, wherein the HC1 comprises from N to C-terminus a heavy chain variable domain (VH) associated with the first antigen binding site , CH1 domain, the Fc domain, linker, and the third antigen binding site. Clause 7. The trispecific antibody or trispecific binding fragment of any one of Clauses 1, 5, and 6, wherein the HC2 comprises a second antigen binding site that specifically binds BCMA, and the HC1 Further comprising a third antigen binding site specifically binding to GPRC5D. Clause 8. The trispecific antibody or trispecific binding fragment of any one of clauses 1 to 7, wherein the first antigen binding site comprises a fragment antigen binding (Fab). Item 9. The trispecific antibody or trispecific binding fragment of any one of Items 1 to 8, wherein the second antigen binding site comprises a single chain variable fragment (scFv). Item 10. The trispecific antibody or trispecific binding fragment of any one of Items 1 to 9, wherein the third antigen binding site comprises a single chain variable fragment (scFv). Clause 11. The trispecific antibody or trispecific binding fragment of any one of Clauses 1 to 10, wherein the Fc domains of HC1 and HC2 comprise one or more different mutations that promote heterodimerization . Clause 12. The trispecific antibody or trispecific binding fragment of clause 11, wherein the Fc domain of the HC1 comprises mutations T366S, L368A, and Y407V (EU numbering), and the Fc domain of the HC2 comprises Mutation T366W (EU number). Clause 13. The trispecific antibody or trispecific binding fragment of Clause 11, wherein the Fc domain of the HC2 comprises mutations T366S, L368A, and Y407V (EU numbering), and the Fc domain of the HC1 comprises Mutation T366W (EU number). Clause 14. The trispecific antibody or trispecific binding fragment of any one of Clauses 1 to 13, wherein the Fc domains of HC1 and / or HC2 further comprise one of reducing Fc binding to Fcγ receptors or multiple mutations. Item 15. The trispecific antibody or trispecific binding fragment of Item 14, wherein the Fcγ receptor is FcyRI, FcyRIIA, FcyRIIB, FcyRIIIA, and / or FcyRIIIB. Clause 16. The trispecific antibody or trispecific binding fragment of Clause 14 or 15, wherein each of the Fc domains of HC1 and / or HC2 comprises a protein selected from the group consisting of L234A, L235A, and D265S (EU numbering). one or more mutations. Clause 17. The trispecific antibody or trispecific binding fragment of Clause 16, wherein the Fc domains of HC1 and HC2 each comprise mutations L234A, L235A, and D265S (EU numbering). Clause 18. The trispecific antibody or trispecific binding fragment of any one of clauses 1 to 17, wherein the Fc domains of HC1 or HC2 further comprise one or more of reducing Fc binding to Protein A mutation. Clause 19. The trispecific antibody or trispecific binding fragment of Clause 18, wherein the Fc domains of HC1 or HC2 comprise mutations H435R and / or Y436F (EU numbering). Item 20. The trispecific antibody or trispecific binding fragment of Item 19, wherein the Fc domain of HCl comprises mutations H435R and Y436F (EU numbering). Clause 21. The trispecific antibody or trispecific binding fragment of any one of clauses 3 and 5 to 18, wherein the linker comprises GGSEGKSSGSGSESKSTGGS (SEQ ID NO: 25) or GGGGSGGGGSGGGGSGGGGS ((G4S) , the amino acid sequence of SEQ ID NO: 163). Clause 22. The trispecific antibody or trispecific binding fragment of any one of Clauses 1 to 21, wherein the first antigen binding site that specifically binds CD3 comprises: comprising GDSVFNNNAAWS (SEQ ID NO: 4) the amino acid sequence of the heavy chain complementarity determining region 1 (CDR1), the heavy chain CDR2 comprising the amino acid sequence of RTYYRSKWLYD (SEQ ID NO: 5), and the amino group comprising GYSSSFDY (SEQ ID NO: 6) Acid sequence of heavy chain CDR3. Item 23. The trispecific antibody or trispecific binding fragment of any one of Items 1 to 22, wherein the first antigen binding site that specifically binds CD3 comprises: comprising TGTSSNIGTYKFVS (SEQ ID NO: 1) the light chain complementarity determining region 1 (CDR1) of the amino acid sequence, the light chain CDR2 comprising the amino acid sequence of EVSKRPS (SEQ ID NO: 2), and the amino group comprising VSYAGSGTLL (SEQ ID NO: 3) Acid sequence of light chain CDR3. Item 24. The trispecific antibody or trispecific binding fragment of any one of Items 1 to 23, wherein the first antigen binding site that specifically binds CD3 comprises a heavy chain variable domain (VH) , the heavy chain variable domain comprises the amino acid sequence of SEQ ID NO: 8. Clause 25. The trispecific antibody or trispecific binding fragment of any one of Clauses 1 to 24, wherein the first antigen binding site that specifically binds CD3 comprises a light chain variable domain (VL) , the light chain variable domain comprises the amino acid sequence of SEQ ID NO: 7. Clause 26. The trispecific antibody or trispecific binding fragment of any one of Clauses 1 to 25, wherein the second or third antigen binding site that specifically binds GPRC5D comprises: comprising GFSLTNIRMSVS (SEQ A heavy chain complementarity determining region 1 (CDR1) comprising the amino acid sequence of ID NO: 12), a heavy chain CDR2 comprising the amino acid sequence of HIFSNDEKS (SEQ ID NO: 13), and comprising MRLPYGMDV (SEQ ID NO: 14) The amino acid sequence of the heavy chain CDR3. Clause 27. The trispecific antibody or trispecific binding fragment of any one of Clauses 1 to 26, wherein the second or third antigen binding site that specifically binds GPRC5D comprises: comprising RSSQSLVHSDGNTYLS (SEQ The light chain complementarity determining region 1 (CDR1) of the amino acid sequence of ID NO: 9), the light chain CDR2 of the amino acid sequence comprising KISNRFF (SEQ ID NO: 10), and the light chain CDR2 comprising the amino acid sequence of MQATQFPHT (SEQ ID NO: 11) The amino acid sequence of the light chain CDR3. Item 28. The trispecific antibody or trispecific binding fragment of any one of Items 1 to 27, wherein the second or third antigen binding site that specifically binds GPRC5D comprises: comprising SEQ ID NO : The heavy chain variable domain (VH) of the amino acid sequence of 16. Clause 29. The trispecific antibody or trispecific binding fragment of any one of Clauses 1 to 28, wherein the second or third antigen binding site that specifically binds GPRC5D comprises: comprising SEQ ID NO : The light chain variable domain (VL) of the amino acid sequence of 15. Item 30. The trispecific antibody or trispecific binding fragment of any one of Items 1 to 29, wherein the second or third antigen binding site that specifically binds BCMA comprises: comprising GFTFSSYAMS (SEQ A heavy chain complementarity determining region 1 (CDR1) comprising the amino acid sequence of ID NO: 20), a heavy chain CDR2 comprising the amino acid sequence of AISGSGGSTY (SEQ ID NO: 21), and comprising DEGYSSGHYYGMDV (SEQ ID NO: 22) The amino acid sequence of the heavy chain CDR3. Clause 31. The trispecific antibody or trispecific binding fragment of any one of Clauses 1 to 30, wherein the second or third antigen binding site that specifically binds BCMA comprises: comprising RASQSISSSFLT (SEQ Light chain complementarity determining region 1 (CDR1) comprising the amino acid sequence of ID NO: 17), light chain CDR2 comprising the amino acid sequence of GASSRAT (SEQ ID NO: 18), and comprising QHYGSSPMYT (SEQ ID NO: 19) The amino acid sequence of the light chain CDR3. Clause 32. The trispecific antibody or trispecific binding fragment of any one of Clauses 1 to 31, wherein the second or third antigen binding site that specifically binds BCMA comprises: comprising SEQ ID NO : The heavy chain variable domain (VH) of the amino acid sequence of 24. Clause 33. The trispecific antibody or trispecific binding fragment of any one of clauses 1 to 32, wherein the second or third antigen binding site that specifically binds BCMA comprises: comprising SEQ ID NO : The light chain variable domain (VL) of the amino acid sequence of 23. Clause 34. The trispecific antibody or trispecific binding fragment of any one of Clauses 1 to 33, wherein the first antigen binding site specifically binds to residues 22 to 35 of the CD3ε chain ( QDGNEEMGGITQTP (SEQ ID NO: 160)). Item 35. The trispecific antibody or trispecific binding fragment of Item 34, wherein the first antigen binding site specifically binds to CD3 with an affinity of about 2.5 x 10-8 M. Item 36. The trispecific antibody or trispecific binding fragment of Item 34, wherein the first antigen binding site specifically binds to CD3 with an affinity of about 3.1 x 10-8 M. Clause 37. The trispecific antibody or trispecific binding fragment of any one of clauses 1 to 36, wherein the second or third antigen binding site specifically binds to residues 17 to 37 of the BCMA BCMW37 chain 26 (LLHACIPCQL (SEQ ID NO: 161)). Item 38. The trispecific antibody or trispecific binding fragment of Item 37, wherein the second or third antigen binding site specifically binds to BCMA with an affinity of about 2.1 x 10-10 M. Item 39. The trispecific antibody or trispecific binding fragment of Item 37, wherein the second or third antigen binding site specifically binds to BCMA with an affinity of about 8.4 x 10-10 M. Item 40. The trispecific antibody or trispecific binding fragment of any one of Items 1 to 39, wherein the antibody or antigen-binding fragment thereof is of the IgGl, IgG2, IgG3, or IgG4 isotype. Item 41. The trispecific antibody or trispecific binding fragment of any one of items 1 to 40, which is of the IgGl isotype. Item 42. The trispecific antibody or trispecific binding fragment of Item 1, wherein the HCl comprises the amino acid sequence of SEQ ID NO: 26. Item 43. The trispecific antibody or trispecific binding fragment of Item 1 or 42, wherein the LC comprises the amino acid sequence of SEQ ID NO: 27.Item 44. The trispecific antibody or trispecific binding fragment of Item 1, 42, or 43, wherein the HC2 comprises the amino acid sequence of SEQ ID NO: 28. Item 45. The trispecific antibody or trispecific binding fragment of Item 1, wherein the HCl comprises the amino acid sequence of SEQ ID NO: 29. Item 46. The trispecific antibody or trispecific binding fragment of Item 1 or 45, wherein the LC comprises the amino acid sequence of SEQ ID NO: 30. Item 47. The trispecific antibody or trispecific binding fragment of Item 1, 45, or 46, wherein the HC2 comprises the amino acid sequence of SEQ ID NO: 31. Clause 48. A trispecific antibody or trispecific binding fragment thereof, comprising: a) a first antigen binding site that specifically binds CD3, b) a second antigen binding site that specifically binds GPRC5D, and c) specifically binding to the third antigen binding site of BCMA. Item 49. The trispecific antibody or trispecific binding fragment of Item 48, wherein the first antigen binding site that specifically binds CD3 comprises: an amino acid comprising GDSVFNNNAAWS (SEQ ID NO: 4) The sequence of heavy chain complementarity determining region 1 (CDR1), the heavy chain CDR2 comprising the amino acid sequence of RTYYRSKWLYD (SEQ ID NO: 5), and the heavy chain CDR3 comprising the amino acid sequence of GYSSSFDY (SEQ ID NO: 6) . Item 50. The trispecific antibody or trispecific binding fragment of Item 48 or 49, wherein the first antigen binding site that specifically binds CD3 comprises: an amine comprising TGTSSNIGTYKFVS (SEQ ID NO: 1) The light chain complementarity determining region 1 (CDR1) of the amino acid sequence, the light chain CDR2 comprising the amino acid sequence of EVSKRPS (SEQ ID NO: 2), and the light chain comprising the amino acid sequence of VSYAGSGTLL (SEQ ID NO: 3) Chain CDR3. Item 51. The trispecific antibody or trispecific binding fragment of any one of Items 48 to 50, wherein the first antigen binding site that specifically binds CD3 comprises a heavy chain variable domain (VH) , the heavy chain variable domain comprises the amino acid sequence of SEQ ID NO: 8. Item 52. The trispecific antibody or trispecific binding fragment of any one of Items 48 to 51, wherein the first antigen binding site that specifically binds CD3 comprises a light chain variable domain (VL) , the light chain variable domain comprises the amino acid sequence of SEQ ID NO: 7. Item 53. The trispecific antibody or trispecific binding fragment of any one of Items 48 to 52, wherein the second antigen binding site that specifically binds GPRC5D comprises: comprising GFSLTNIRMSVS (SEQ ID NO: 12) the amino acid sequence of heavy chain complementarity determining region 1 (CDR1), the heavy chain CDR2 comprising the amino acid sequence of HIFSNDEKS (SEQ ID NO: 13), and the amino group comprising MRLPYGMDV (SEQ ID NO: 14) Acid sequence of heavy chain CDR3. Item 54. The trispecific antibody or trispecific binding fragment of any one of Items 48 to 53, wherein the second antigen binding site that specifically binds GPRC5D comprises: comprising RSSQSLVHSDGNTYLS (SEQ ID NO: 9) the light chain complementarity determining region 1 (CDR1) of the amino acid sequence, the light chain CDR2 comprising the amino acid sequence of KISNRFF (SEQ ID NO: 10), and the amino group comprising MQATQFPHT (SEQ ID NO: 11) Acid sequence of light chain CDR3. Item 55. The trispecific antibody or trispecific binding fragment of any one of Items 48 to 54, wherein the second antigen binding site that specifically binds GPRC5D comprises a heavy chain variable domain (VH) , the heavy chain variable domain comprises the amino acid sequence of SEQ ID NO: 16. Item 56. The trispecific antibody or trispecific binding fragment of any one of Items 48 to 55, wherein the second antigen binding site that specifically binds GPRC5D comprises a light chain variable domain (VL) , the light chain variable domain comprises the amino acid se...

Claims

1. A trispecific antibody or a trispecific binding fragment thereof, comprising: (a) a first antigen-binding arm comprising a first heavy chain variable domain (VH1) and a first light chain variable domain (VL1), wherein the first antigen-binding arm comprises a heavy chain complementarity-determining region (HCDR) 1 containing an amino acid sequence of GDSVFNNNAAWS (SEQ ID NO: 4), an HCDR2 containing an amino acid sequence of RTYYRSKWLYD (SEQ ID NO: 5), an HCDR3 containing an amino acid sequence of GYSSSFDY (SEQ ID NO: 6), a light chain complementarity-determining region (LCDR) 1 containing an amino acid sequence of TGTSSNIGTYKFVS (SEQ ID NO: 1), an LCDR2 containing an amino acid sequence of EVSKRPS (SEQ ID NO: 2), and an LCDR3 containing an amino acid sequence of VSYAGSGTLL (SEQ ID NO: 3); (b) A second antigen-binding arm comprising a second heavy chain variable domain (VH2) and a second light chain variable domain (VL2), wherein the second antigen-binding arm comprises HCDR1 containing the amino acid sequence GFSLTNIRMSVS (SEQ ID NO: 12), HCDR2 containing the amino acid sequence HIFSNDEKS (SEQ ID NO: 13), HCDR3 containing the amino acid sequence MRLPYGMDV (SEQ ID NO: 14), LCDR1 containing the amino acid sequence RSSQSLVHSDGNTYLS (SEQ ID NO: 9), LCDR2 containing the amino acid sequence KISNRFF (SEQ ID NO: 10), and LCDR3 containing the amino acid sequence MQATQFPHT (SEQ ID NO: 11);(c) A third antigen-binding arm comprising a third heavy chain variable domain (VH3) and a third light chain variable domain (VL3), wherein the third antigen-binding arm comprises HCDR1 containing the amino acid sequence GFTFSSYAMS (SEQ ID NO: 20), HCDR2 containing the amino acid sequence AISGSGGSTY (SEQ ID NO: 21), and HCDR3 containing the amino acid sequence DEGYSSGHYYGMDV (SEQ ID NO: 22), and LCDR1 containing the amino acid sequence RASQSISSSFLT (SEQ ID NO: 17), LCDR2 containing the amino acid sequence GASSRAT (SEQ ID NO: 18), and LCDR3 containing the amino acid sequence QHYGSSPMYT (SEQ ID NO: 19), wherein the first antigen-binding arm binds to an epitope on differentiation cluster 3 (CD3), and the second antigen-binding arm binds to member D of group 5 of the G protein-coupled receptor family C. The epitope on (GPRC5D) and the third antigen-binding arm binds to the epitope on the B-cell maturation antigen (BCMA).

2. A trispecific antibody or trispecific binding fragment as described in claim 1, wherein: (a) The VH1 and VL1 of the first antigen-binding arm are present in Fab, a bivalent antibody, Fab', F(ab')2, Fv, scFv, Fd, a disulfide-bonded stable Fv fragment (dsFv), or a disulfide-bonded stable bivalent antibody (ds bivalent antibody); (b) The VH2 and VL2 of the second antigen-binding arm are present in scFv, a bivalent antibody, Fab, Fab', F(ab')2, Fv, Fd, a disulfide-bonded stable Fv fragment (dsFv), or a disulfide-bonded stable bivalent antibody (ds bivalent antibody); and / or (c) The VH3 and VL3 of the third antigen-binding arm are present in scFv, an antibody fragment, a bivalent antibody, Fab, Fab', F(ab')2, Fv, Fd, a disulfide-bonded stable Fv fragment (dsFv), or a disulfide-bonded stable bivalent antibody (ds bivalent antibody).

3. The trispecific antibody or trispecific binding fragment as described in claim 1, wherein the first antigen-binding arm binding to CD3 comprises the VH1 of SEQ ID NO: 8 and the VL1 of SEQ ID NO:

7.

4. The trispecific antibody or trispecific binding fragment as described in claim 1, wherein the second antigen binding arm binding GPRC5D comprises the VH2 of SEQ ID NO: 16 and the VL2 of SEQ ID NO:

15.

5. The trispecific antibody or trispecific binding fragment as described in claim 1, wherein the third antigen binding arm binding to BCMA comprises the VH3 of SEQ ID NO: 24 and the VL3 of SEQ ID NO:

23.

6. The trispecific antibody or trispecific binding fragment as described in claim 1, wherein the first antigen-binding arm binding to CD3 comprises VH1 of SEQ ID NO: 8 and VL1 of SEQ ID NO: 7; the second antigen-binding arm binding to GPRC5D comprises VH2 of SEQ ID NO: 16 and VL2 of SEQ ID NO: 15; and the third antigen-binding arm binding to BCMA comprises VH3 of SEQ ID NO: 24 and VL3 of SEQ ID NO:

23.

7. A trispecific antibody or trispecific binding fragment as claimed in claim 1, wherein the first antigen-binding arm comprises a crystallizable fragment (Fc) domain, and the second antigen-binding arm or the third antigen-binding arm comprises an Fc domain.

8. The trispecific antibody or trispecific binding fragment as described in claim 7, wherein the Fc domain of the first antigen-binding arm contains the amino acid sequence of SEQ ID NO:

158.

9. A trispecific antibody or trispecific binding fragment as described in claim 7, wherein the Fc domains contain one or more mutations that promote heterodimerization of the Fc domains, wherein, according to EU numbers, the mutations are selected from T366S, L368A, T366W, and Y407V.

10. A trispecific antibody or trispecific binding fragment as described in claim 7, wherein the Fc domain further comprises one or more mutations that reduce the binding of Fc to the Fcγ receptor, wherein, according to the EU designation, the Fc domain comprises one or more mutations selected from L234A, L235A, and D265S.

11. A trispecific antibody or trispecific binding fragment as described in claim 7, wherein the Fc domain further comprises one or more mutations that reduce Fc binding to protein A, wherein, according to the EU designation, the Fc domain comprises mutations H435R and / or Y436F.

12. The trispecific antibody or trispecific binding fragment as described in claim 1, wherein the first antigen-binding arm specifically binds to QDGNEEMGGITQTP (SEQ ID NO: 161) of the CD3ε chain.

13. A trispecific antibody or trispecific binding fragment as described in claim 1, wherein the first antigen-binding arm specifically binds to CD3 with an affinity of about 2 x 10⁻⁸ to 4 x 10⁻⁸ M.

14. The trispecific antibody or trispecific binding fragment as described in claim 1, wherein the third antigen-binding arm specifically binds to the LLHACIPCQL (SEQ ID NO: 162) of the BCMA BCMW37 chain.

15. A trispecific antibody or trispecific binding fragment as described in claim 1, wherein the third antigen-binding arm specifically binds to BCMA with an affinity of about 2 x 10⁻¹⁰ to 9 x 10⁻¹⁰ M.

16. The trispecific antibody or its trispecific binding fragment as claimed in claim 1, comprising a first antigen-binding arm binding to an epitope on differentiation cluster 3 (CD3), a second antigen-binding arm binding to an epitope on G protein-coupled receptor family C group 5 member D (GPRC5D), and a third antigen-binding arm binding to an epitope on B cell maturation antigen (BCMA), wherein the first antigen-binding arm comprises a heavy chain (HC1) polypeptide and a light chain (LC) polypeptide, wherein the heavy chain (HC1) polypeptide further comprises the second antigen-binding arm, and wherein the trispecific antibody or its trispecific binding fragment further comprises a single polypeptide that comprises the third antigen-binding arm.

17. The trispecific antibody or trispecific binding fragment as claimed in claim 16, wherein the first antigen-binding arm comprises: HC1 comprising the amino acid sequence of SEQ ID NO: 29, and LC comprising the amino acid sequence of SEQ ID NO: 30, and the single polypeptide comprising the third antigen-binding arm comprises the amino acid sequence of SEQ ID NO:

31.

18. The trispecific antibody or trispecific binding fragment as claimed in claim 1, comprising a polypeptide comprising the amino acid sequence of SEQ ID NO: 29, comprising the second antigen-binding arm and the first antigen-binding arm (HC), a polypeptide comprising the amino acid sequence of SEQ ID NO: 30, comprising the first antigen-binding arm (LC), and a polypeptide comprising the amino acid sequence of SEQ ID NO: 31, comprising the third antigen-binding arm.

19. The trispecific antibody or its trispecific binding fragment as claimed in claim 1, comprising a first antigen-binding arm binding to an epitope on differentiation cluster 3 (CD3), a second antigen-binding arm binding to an epitope on G protein-coupled receptor family C group 5 member D (GPRC5D), and a third antigen-binding arm binding to an epitope on B cell maturation antigen (BCMA), wherein the first antigen-binding arm comprises a heavy chain (HC1) polypeptide and a light chain (LC) polypeptide; and wherein the trispecific antibody or its trispecific binding fragment comprises a single polypeptide comprising the second antigen-binding arm and the third antigen-binding arm.

20. The trispecific antibody or trispecific binding fragment as claimed in claim 19, wherein the first antigen-binding arm comprises: HC1 comprising the amino acid sequence of SEQ ID NO: 26, and LC comprising the amino acid sequence of SEQ ID NO: 27, and the polypeptide comprising the second antigen-binding arm and the third antigen-binding arm comprises the amino acid sequence of SEQ ID NO:

28.

21. The trispecific antibody or trispecific binding fragment as claimed in claim 1, comprising: a polypeptide comprising the amino acid sequence of SEQ ID NO: 26, comprising the HC of the first antigen binding arm; a polypeptide comprising the amino acid sequence of SEQ ID NO: 27, comprising the LC of the first antigen binding arm; and a polypeptide comprising the amino acid sequence of SEQ ID NO: 28, comprising the second antigen binding arm and the third antigen binding arm.

22. The trispecific antibody or trispecific binding fragment as described in claim 1, wherein the antibody or its antigen-binding fragment is of human IgG1 isotype.

23. A pharmaceutical composition comprising a trispecific antibody or trispecific binding fragment as described in any one of claims 1 to 22 and a pharmaceutically acceptable carrier.

24. The pharmaceutical composition as claimed in claim 23, wherein the pharmaceutical composition further comprises a second therapeutic agent.

25. The pharmaceutical composition as claimed in claim 24, wherein the second therapeutic agent comprises an anti-CD38 agent, an immunomodulatory amide drug (IMiD), an immune checkpoint inhibitor, an immune co-stimulator, a gamma secretase inhibitor, a T-cell enhancer, or any combination thereof.

26. A cell that exhibits a trispecific antibody or trispecific binding fragment as described in any one of claims 1 to 22.

27. The cell as described in claim 26, wherein: (a) The cell line fusion tumor; or (b) The trispecific antibody system produced via recombinant synthesis.

28. Use of a trispecific antibody or trispecific binding fragment as described in any one of claims 1 to 22, or a pharmaceutical composition as described in any one of claims 23 to 25, for the preparation of a medicament for treating cancer, wherein a therapeutically effective amount of the trispecific antibody or trispecific binding fragment, or the pharmaceutical composition, is administered to a subject.

29. The use as described in claim 28, wherein the trispecific antibody or trispecific binding fragment or the pharmaceutical composition is administered for a time sufficient to treat the cancer.

30. Use of a trispecific antibody or trispecific binding fragment as described in any one of claims 1 to 22, or a pharmaceutical composition as described in any one of claims 23 to 25, for the preparation of a medicament for inhibiting the growth or proliferation of cancer cells, wherein an effective amount of the trispecific antibody or trispecific binding fragment, or the pharmaceutical composition, is administered to the cell, wherein the effective amount is sufficient to inhibit the growth or proliferation of the cancer cells.

31. The use as described in claim 30, wherein the cancer cells are in the object and the trispecific antibody or trispecific binding fragment, or the pharmaceutical composition, is administered to the object.

32. Use of a trispecific antibody or trispecific binding fragment as described in any one of claims 1 to 22, or a pharmaceutical composition as described in any one of claims 23 to 25, for the preparation of a medicament for redirecting T cells in a subject to BCMA and / or GPRC5D efficacious cancer cells, wherein a therapeutically effective amount of the trispecific antibody or trispecific binding fragment or the pharmaceutical composition is administered to the subject.

33. The use as described in claim 32, wherein the therapeutically effective amount is sufficient to direct the T-cell response toward the cancer cells.

34. The use as described in any one of claims 28 to 33, wherein the cancer is multiple myeloma.

35. The use as described in any one of claims 28 to 33, wherein the cancer is smoldering multiple myeloma (SMM).

36. The use as described in any one of claims 28 to 33, wherein the cancer is recurrent, refractory, or malignant, or any combination thereof.

37. The use as described in any of claims 28 to 33, wherein the subject has received prior treatment.

38. The use as described in claim 37, wherein the prior treatment comprises a proteasome inhibitor, an immunomodulatory agent, a CD38 antibody, a bispecific agent, CAR-T therapy, or a combination thereof.

39. The use as described in any of claims 28 to 33, wherein the second therapeutic agent is administered.

40. The use as described in claim 39, wherein the second therapeutic agent is a chemotherapeutic agent, wherein the chemotherapeutic agent is cytarabine, anthracycline, histamine dihydrochloride, or interleukin-2 (IL-2).

41. The use as described in claim 39, wherein the second therapeutic agent is an anti-CD38 agent, an immunomodulatory amide drug (IMiD), an immune checkpoint inhibitor, an immune co-stimulator, a gamma secretase inhibitor, a T-cell enhancer, or any combination thereof.

42. The use as described in any one of claims 28 to 33, wherein the trispecific antibody or trispecific binding fragment, or the pharmaceutical composition, is administered to the subject intravenously, intramuscularly, intraperitoneally, and / or subcutaneously.

43. The use as described in claim 42, wherein the trispecific antibody or trispecific binding fragment, or the pharmaceutical composition, is administered subcutaneously to the subject.

44. A method for generating a trispecific antibody or trispecific binding fragment as described in any one of claims 1 to 22, wherein the method comprises culturing cells as described in claim 26 or claim 27 and isolating the trispecific antibody or trispecific binding fragment.

45. A synthetic polynucleotide encoding a trispecific antibody or trispecific binding fragment as described in any one of claims 1 to 22.

46. ​​A kit comprising (i) a trispecific antibody or trispecific binding fragment as described in any one of claims 1 to 22 and / or a polynucleotide as described in claim 45 and (ii) its packaging.

47. A trispecific antibody comprising: (a) a first heavy chain (HC1); (b) a light chain (LC); and (c) a second heavy chain (HC2), wherein the HC1 comprises the amino acid sequence of SEQ ID NO: 29, the LC comprises the amino acid sequence of SEQ ID NO: 30, and the HC2 comprises the amino acid sequence of SEQ ID NO: 31.

Images