Anti-GPRC5a antibody and uses thereof

Abstract

The present invention addresses the problem of providing: an anti-GPRC5A antibody that binds to GPRC5A on a cell surface; and an antibody-drug conjugate that contains the antibody, or a pharmaceutical composition that contains the antibody-drug conjugate. A novel mouse anti-GPRC5A antibody was obtained by immunizing a mouse with a cell line that expresses human GPRC5A or a human GPRC5A protein (Example 1). Furthermore, nine types of human chimeric anti-GPRC5A antibodies and humanized anti-GPRC5A antibodies were obtained from the anti-GPRC5A antibody on the basis of the sequence information of the mouse antibody (Examples 4 and 6). Furthermore, an antibody-drug conjugate (ADC) was produced using the anti-GPRC5A antibody, and it has been found that the ADC binds to GPRC5A-expressing cancer cells and has an activity of damaging the cells (Examples 8 and 9). In addition, a (human chimeric anti-GPRC5A antibody)-(drug) conjugate exhibited an antitumor effect in a mouse subcutaneous xenograft model (Example 10). From these results, it has been confirmed that the obtained novel human chimeric anti-GPRC5A antibody is useful for the targeting for delivering a pharmacologically active substance to GPRC5A-expressing cells.

Description

Anti-GPRC5A antibody and its use

[0001] The present invention relates to a novel anti-GPRC5A antibody and its use. More particularly, the present invention relates to an anti-GPRC5A antibody or its antigen-binding fragment that binds to GPRC5A and has an internalization effect, a method for producing the anti-GPRC5A antibody, an antibody-drug conjugate containing the antibody, a pharmaceutical composition containing the antibody-drug conjugate, and its use.

[0002] G-protein coupled receptor family C group 5 member A (GPRC5A) is one of the G protein-coupled receptors classified as GPCR family C group 5 receptors. There are four subtypes of GPRC5 receptors: GPRC5A, GPRC5B, GPRC5C, and GPRC5D. Since their expression is induced by retinoic acid stimulation, they are also known as retinoic acid-inducible orphan G protein-coupled receptors (RAIG) (Patent Document 1).

[0003] Recent studies have reported that microbial metabolites such as 7-fluorotryptamine act as physiological ligands for GPRC5A (Non-Patent Literature 1). Furthermore, GPRC5A has been reported to be associated with cancer-related signaling pathways such as NF-κB, cAMP-Gsα, FAK / Src, and STAT3 (Non-Patent Literature 2). However, its physiological function remains largely unknown.

[0004] Overexpression of the GPRC5A gene has been reported in breast cancer, colorectal cancer, gastric cancer, liver cancer, pancreatic cancer, prostate cancer, ovarian cancer, etc., and it has been shown that GPRC5A is involved in the development and progression of these cancers (Patent Document 2, Non-Patent Documents 3, 4). Furthermore, it has been shown that GPRC5A overexpression correlates with poor prognosis in patients with gastric cancer, pancreatic cancer, colorectal cancer, and oral cancer (Non-Patent Documents 5-7). In addition, it is known to be involved in resistance to anticancer drugs such as gemcitabine, oxaliplatin, and paclitaxel (Patent Document 3, Non-Patent Documents 8, 9), and in the survival of cancer cells under hypoxic conditions (Non-Patent Document 10).

[0005] As described above, the association between GPRC5A and cancer suggests that GPRC5A may be an excellent therapeutic target for cancer. However, to date, no prescription drugs targeting GPRC5A have been developed.

[0006] WO2003 / 016553WO2019 / 067709CN117327657A

[0007] Nat. Chem. Biol. , 2023, Vol. 19(10): p. 1205-1214 Biomed. Res. Int. , 2018: 1823726 Front Pharmacol. , 2018, Vol. 9:431PLoS One, 2017, Vol. 12(1): e0170390 Tumor Biol. , 2016, Vol. 37(1): p. 503-10 Cancer Cell Int. , 2021, Vol. 21(1):620Exp. Mol. Pathol. , 2019, Vol. 107:p. 51-56 Int. J. Mol. Sci. , 2018, Vol. 19(7):1870Cell Death Dis. , 2016, Vol. 7(7): e2294EMBO Mol. Med. , 2018, Vol. 10(11):e8699

[0008] The object of the present invention is to provide an anti-GPRC5A antibody that binds to GPRC5A on the cell surface, and to provide an antibody-drug conjugate containing the antibody or a pharmaceutical composition containing the antibody-drug conjugate.

[0009] The inventors conducted extensive and creative research in producing anti-GPRC5A antibodies that bind to GPRC5A. As a result, they immunized mice with a cell line expressing human GPRC5A or with human GPRC5A protein and obtained a novel mouse anti-GPRC5A antibody (Example 1). Furthermore, based on the sequence information of the mouse antibody, they obtained nine types of human chimeric anti-GPRC5A antibodies and five types of humanized anti-GPRC5A antibodies from the anti-GPRC5A antibody (Examples 4 and 6). Then, they produced antibody-drug conjugates (ADCs) using these anti-GPRC5A antibodies and found that the ADCs bind to cancer cells expressing GPRC5A and have the effect of damaging those cells (Examples 8, 9, and 10). Based on these results, we confirmed that the newly acquired novel human chimeric anti-GPRC5A antibody and novel humanized anti-GPRC5A antibody are useful for targeting GPRC5A-expressing cells in modalities that deliver pharmacologically active substances to cells such as ADCs, thus completing the present invention.

[0010] In other words, the present invention is not limited to the following, but relates to [1] to

[23] . [1] An anti-GPRC5A antibody or its antigen-binding fragment comprising a heavy chain variable region and a light chain variable region as described in any of (a) to (n) below: (a) A heavy chain variable region comprising CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 3, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 3, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 3, and a light chain variable region comprising CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 4, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 4, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 4; (b) A heavy chain variable region including CDR1 consisting of the amino acid sequence of amino acids 31 to 35 of SEQ ID NO: 5, CDR2 consisting of the amino acid sequence of amino acids 50 to 66 of SEQ ID NO: 5, and CDR3 consisting of the amino acid sequence of amino acids 99 to 113 of SEQ ID NO: 5, and a light chain variable region including CDR1 consisting of the amino acid sequence of amino acids 24 to 34 of SEQ ID NO: 6, CDR2 consisting of the amino acid sequence of amino acids 50 to 56 of SEQ ID NO: 6, and CDR3 consisting of the amino acid sequence of amino acids 89 to 97 of SEQ ID NO: 6; (c) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 7, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 7, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 108 of SEQ ID NO: 7; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 8, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 8, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 8;(d) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 9, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 9, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 108 of SEQ ID NO: 9, and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 10, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 10, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 10; (e) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 11, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 11, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 109 of SEQ ID NO: 11; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 34 of SEQ ID NO: 12, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 56 of SEQ ID NO: 12, and CDR3 consisting of amino acid sequences from amino acid numbers 89 to 97 of SEQ ID NO: 12; (f) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 13, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 13, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 112 of SEQ ID NO: 13; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 14, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 14, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 14;(g) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 15, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 15, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 108 of SEQ ID NO: 15; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 16, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 16, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 16; (h) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 17, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 17, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 17; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 18, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 18, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 18; and (i) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 19, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 19, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 109 of SEQ ID NO: 19; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 34 of SEQ ID NO: 20, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 56 of SEQ ID NO: 20, and CDR3 consisting of amino acid sequences from amino acid numbers 89 to 97 of SEQ ID NO: 20;and (j) a heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 39, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 39, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 39, and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 40, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 40, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 40; and (k) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 41, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 41, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 41; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 42, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 42, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 42; and (l) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 43, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 43, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 43; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 44, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 44, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 44;and (m) a heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 45, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 45, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 45, and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 46, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 46, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 46; and (n) A heavy chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 31 to 35 of SEQ ID NO: 47, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 66 of SEQ ID NO: 47, and CDR3 consisting of the amino acid sequence from amino acid numbers 99 to 109 of SEQ ID NO: 47, and a light chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 24 to 34 of SEQ ID NO: 48, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 56 of SEQ ID NO: 48, and CDR3 consisting of the amino acid sequence from amino acid numbers 89 to 97 of SEQ ID NO: 48. [2] The anti-GPRC5A antibody or antigen-binding fragment thereof according to [1], comprising the heavy chain variable region and light chain variable region described in any of (a) to (n) below: (a) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 3, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 4; (b) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 5, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 6; (c) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 7, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 8; (d) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 9, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 10; (e) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 11, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 12; (f) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 13, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 14; (g) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 15, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 16;(h) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 17 and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 18; and (i) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 19 and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 20; and (j) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 39 and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 40; and (k) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 41 and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 42; and (l) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 43 and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 44; and (m) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 45 and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 46; and (n) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 47 and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 48. [3] The anti-GPRC5A antibody according to [2], which is an IgG antibody. [4] The anti-GPRC5A antibody or an antigen-binding fragment thereof according to any one of [1] to [3], wherein any amino acid residue is substituted with cysteine or a non-natural amino acid. [5] The anti-GPRC5A antibody or an antigen-binding fragment thereof according to any one of [1] to [4], which is post-translationally modified. [6] The anti-GPRC5A antibody or an antigen-binding fragment thereof according to [5], wherein the post-translational modification is addition of N-linked or O-linked sugar chains, N-terminal or C-terminal processing, deamidation, isomerization of aspartic acid, and / or oxidation of methionine. [7] A complex comprising the anti-GPRC5A antibody or an antigen-binding fragment thereof according to any one of [1] to [6]. [8] The complex according to [7], wherein the complex is any one of an antibody-drug conjugate, a radioisotope-labeled antibody, and a multispecific antibody. [9] The following formula (I) in which a drug is bound to the anti-GPRC5A antibody or an antigen-binding fragment thereof according to any one of [1] to [6] via a linker: Ab-(L; １ -D １ n １１ -D ２ n １２ ―…-D ｐ n １Ｎ )m １ -(L ２ -D １ n２１ ―D ２ n ２２ ―…-D ｐ n ２Ｎ )m ２ -...- (L Ｋ -D １ n Ｋ１ ―D ２ n Ｋ２ ―…-D ｐ n ＫＮ )m ｋ (I) In formula (I), Ab is an anti-GPRC5A antibody or its antigen-binding fragment, and D １ ~D ｐ It is a drug, L １ ~L Ｋ is a linker, n １１ ~n ＫＮ , m １ ~m ｋ An anti-GPRC5A antibody-drug conjugate in which each is an arbitrary integer greater than or equal to 0.

[10] The anti-GPRC5A antibody-drug conjugate according to [9], wherein the drug is a cytotoxic agent.

[11] The anti-GPRC5A antibody-drug conjugate according to

[10] , wherein the cytotoxic agent is a DNA inhibitor or a microtubule polymerization inhibitor.

[12] The drug is of the following formulas: (IIa), (IIb), (IIIa), or (IIIb): (IIa) (IIb) (IIIa) (IIIb) The anti-GPRC5A antibody-drug conjugate according to

[10] , comprising MMAE, MMAF, exatecan, or an exatecan derivative DXd, wherein the wavy line in the formula indicates a linkage.

[13] The anti-GPRC5A antibody-drug conjugate according to any one of

[10] to

[12] , wherein the linker is an enzymatically cleavable linker.

[14] The linker is one of the following formulas (IV) to (VIII): (IV) (V) (VI) (VII) An anti-GPRC5A antibody-drug conjugate according to any one of [7] to

[13] , comprising (VIII), wherein m is the number of [(linker)-(drug)] moieties covalently linked to the antibody, D is a drug, Ab is an anti-GPRC5A antibody as described herein, and S is a sulfur atom of the antibody.

[15] The following linker is defined as (IV): (IV) The anti-GPRC5A antibody-drug conjugate according to

[13] , comprising a Val-Cit linker, wherein m is the number of [(linker)-(drug)] moieties covalently linked to the antibody, D is a drug, Ab is an anti-GPRC5A antibody as described herein, and S is a sulfur atom of the antibody.

[16] The linker-drug is one of the following formulas (IX) to (XIII): (IX) (X) (XI) (XII) An anti-GPRC5A antibody-drug conjugate according to any one of [7] to

[14] , comprising (XIII), wherein m is the number of [(linker)-(cytotoxic agent)] moieties covalently linked to the antibody, Ab is an anti-GPRC5A antibody as described herein, and S is the sulfur atom of the antibody.

[17] A pharmaceutical composition comprising an anti-GPRC5A antibody or its antigen-binding fragment or complex, etc., or an anti-GPRC5A antibody-drug conjugate according to any one of [1] to

[16] , and a pharmaceutically acceptable excipient.

[18] An anti-GPRC5A antibody or its antigen-binding fragment or complex, etc., or an anti-GPRC5A antibody-drug conjugate according to any one of [1] to

[16] , for use in the treatment of cancer.

[19] The pharmaceutical composition according to

[17] for use in the treatment of cancer.

[20] A method for treating cancer, comprising the step of administering a therapeutically effective amount of an anti-GPRC5A antibody or its antigen-binding fragment, or a complex, or an anti-GPRC5A antibody-drug conjugate, as described in any of [1] to

[16] .

[21] Use of an anti-GPRC5A antibody or its antigen-binding fragment, or a complex, or an anti-GPRC5A antibody-drug conjugate, as described in any of [1] to

[16] , in the manufacture of a pharmaceutical composition for the treatment of cancer.

[22] A polynucleotide encoding an amino acid sequence as described in any of [1] to [6].

[23] A vector comprising the polynucleotide described in

[22] .

[24] A host cell comprising the polynucleotide described in

[22] or the vector described in

[23] .

[25] A method for producing an anti-GPRC5A antibody or its antigen-binding fragment, comprising the step of culturing the host cell described in

[24] .

[0011] The anti-GPRC5A antibody or its antigen-binding fragment of the present invention selectively binds to GPRC5A expressed on the cell surface. The antibody-drug conjugate, formed by attaching a drug to the anti-GPRC5A antibody or its antigen-binding fragment via a linker, binds to GPRC5A expressed on the cell surface and is internalized, leading to internalization into the cell. The drug is then released by lysosomes, causing damage to the cell. Therefore, the anti-GPRC5A antibody or its antigen-binding fragment is useful for targeting target cells and delivering effectors such as drugs to those cells.

[0012] Figure 1 shows the results of flow cytometry analysis to evaluate the cell binding affinity of mouse anti-GPRC5A antibodies (1B1, 26C11, 34G2, 43B7, 43D11, 47G10-2, 48B4, and 52D6). Figure 1-1 shows the binding affinity to the 293T cell line that stably expresses human GPRC5A protein (hereinafter referred to as "293T-hGPRC5A cells"), and Figure 1-2 shows the binding affinity to 293T cells. R&D's mouse anti-GPRC5A antibody was used as a reference. The vertical axis shows the average fluorescence intensity calculated by flow cytometry analysis. Figure 2 shows the results of flow cytometry analysis to evaluate the cell binding affinity of mouse anti-GPRC5A antibodies (1B1, 26C11, 34G2, 43B7, 43D11, 47G10-2, 48B4, and 52D6). Figure 2-1 shows the binding affinity to CHO-K1-hGPRC5A cells, and Figure 2-2 shows the binding affinity to CHO-K1 cells. R&D's mouse anti-GPRC5A antibody was used as a reference. The vertical axis shows the average fluorescence intensity calculated by flow cytometry analysis. Figure 3 shows the results of flow cytometry analysis to evaluate the cell binding affinity of mouse anti-GPRC5A antibodies (1B1, 26C11, 34G2, 43B7, 43D11, 47G10-2, 48B4, and 52D6). Figure 3-1 shows the binding affinity to KP-3 cells, Figure 3-2 shows the binding affinity to MIA PaCa-2 cells, and Figure 3-3 shows the binding affinity to Panc-1 cells. R&D's mouse anti-GPRC5D antibody was used as a reference. The vertical axis shows the average fluorescence intensity calculated by flow cytometry analysis. Figure 4 shows the results of evaluating the uptake of mouse anti-GPRC5A antibodies (1B1, 26C11, 34G2, 43B7, 43D11, 47G10-2, 48B4, and 52D6) in cells by internalization assay. Figure 4-1 shows the uptake in 293T-hGPRC5A cells, and Figure 4-2 shows the uptake in 293T cells. Mouse IgG2a and mouse IgG2b antibodies were used as references. The vertical axis shows the fluorescence intensity at an excitation wavelength of 550 nm and an emission wavelength of 590 nm.Figure 5 shows the results of flow cytometry analysis to evaluate the cell binding affinity of human chimeric anti-GPRC5A antibodies (h1B1, h26C11, h34G2A, h34G2L, h43B7, h43D11, h47G10-2, h48B4, and h52D6). Figures 5-1 and 5-2 show the binding affinity to 293T-hGPRC5A cells, and Figures 5-3 and 5-4 show the binding affinity to 293T cells. The vertical axis shows the average fluorescence intensity calculated by flow cytometry analysis. Figure 6 shows the results of flow cytometry analysis to evaluate the cell binding affinity of human chimeric anti-GPRC5A antibodies (h1B1, h26C11, h34G2A, h34G2L, h43B7, h43D11, h47G10-2, h48B4, and h52D6). Figures 6-1 and 6-2 show the binding affinity to KP-3 cells, Figures 6-3 and 6-4 show the binding affinity to MIA PaCa-2 cells, and Figures 6-5 and 6-6 show the binding affinity to Panc-1 cells. The vertical axis shows the average fluorescence intensity calculated by flow cytometry analysis. Figure 7 shows the results of flow cytometry analysis to evaluate the cell binding affinity of human chimeric anti-GPRC5A antibodies (h1B1, h26C11, h34G2A, h34G2L, h43B7, h43D11, h47G10-2, h48B4, and h52D6). Figure 7-1 shows the binding affinity to 293T-hGPRC5D cells, and Figure 7-2 shows the binding affinity to 293T-vect cells. R&D's mouse anti-GPRC5D antibody was used as a reference. The vertical axis shows the average fluorescence intensity calculated by flow cytometry analysis. Figure 8 shows the results of flow cytometry analysis to evaluate the cell binding affinity of human chimeric anti-GPRC5A antibody-drug conjugates (h1B1-MMAE, h26C11-MMAE, h34G2L-MMAE, h43B7-MMAE, h43D11-MMAE, h48B4-MMAE, and h52D6-MMAE) and human chimeric anti-GPRC5A antibodies (h1B1, h26C11, h34G2L, h43B7, h43D11, h48B4, and h52D6). Figures 8-1 and 8-2 show the results of flow cytometry analysis to evaluate the binding affinity to MIA PaCa-2 cells, and Figures 8-3 and 8-4 show the results of flow cytometry analysis to evaluate the binding affinity to Panc-1 cells. Human IgG1 antibody was used as a reference.The vertical axis shows the average fluorescence intensity calculated by flow cytometry analysis. Figure 9 shows the results of evaluating the cytotoxic activity of human chimeric anti-GPRC5A antibody-drug conjugates (h1B1-MMAE, h26C11-MMAE, h34G2L-MMAE, h43B7-MMAE, h43D11-MMAE, h48B4-MMAE, and h52D6-MMAE) against cells. Figures 9-1 and 9-2 show the cytotoxic activity against MIA PaCa-2 cells, Figures 9-3 and 9-4 show the cytotoxic activity against Panc-1 cells, Figure 9-5 shows the cytotoxic activity against MIA PaCa-2 cell spheroids, and Figure 9-6 shows the cytotoxic activity against Panc-1 cell spheroids. Human IgG1-MMAE was used as a reference. The vertical axis shows the cell viability (%) calculated from the luminescence measured by CellTiter-Glo. Figure 10 shows the results of evaluating the cytotoxic activity of humanized anti-GPRC5A antibody-drug conjugate (Hu48B4-1-MMAE) against cells. The vertical axis shows the cell viability (%) calculated from the luminescence measured by CellTiter-Glo. Figure 11 shows the antitumor effect of human chimeric anti-GPRC5A antibody-drug conjugate (h48B4-MMAE) in nude mice subcutaneously transplanted with MIA PaCa-2 cells. The vertical axis shows the average tumor volume calculated from the long and short diameters of the transplanted tumors.

[0013] The present invention will be described in detail below. <Definitions>

[0014] Terms used herein shall be used in the sense commonly used by those skilled in the art unless otherwise defined below.

[0015] In this specification, "immunoglobulin" refers to a protein having the structure of a naturally occurring antibody. Immunoglobulins are glycoproteins based on a symmetrical four-chain Y-shaped structure consisting of two single-sequence heavy chains and two single-sequence light chains. There are five classes of immunoglobulins: IgG, IgM, IgA, IgD, and IgE. The basic structure of immunoglobulins is common to all classes, with two heavy chains and two light chains linked by disulfide bonds and non-covalent bonds. The heavy chain of an immunoglobulin consists of one of five types called α (IgA), δ (IgD), ε (IgE), γ (IgG), or μ (IgM), and furthermore, IgG has subclasses IgG1, IgG2, IgG3, and IgG4. The light chain of an immunoglobulin consists of one of two types called kappa (κ) and lambda (λ), based on the amino acid sequence of its constant domain. The two types of light chains can be paired with any type of heavy chain.

[0016] The heavy chain of immunoglobulins has a heavy chain variable region (VH) and a heavy chain constant region (CH) extending from the N-terminus to the C-terminus. The CH is further divided into three domains from the N-terminus: the CH1 domain, the CH2 domain, and the CH3 domain. The light chain has a light chain variable region (VL) and a light chain constant region (CL) extending from the N-terminus to the C-terminus. In both the heavy and light chains, the domain located at the amino terminus (also referred to herein as the "N-terminus") is called the variable region. The variable region has diverse amino acid sequences even in antibodies produced from the same class (or subclass) of the same animal species, and is known to be involved in the binding specificity of antibodies to antigens. The amino acid sequence of the domain downstream of the variable region, at the carboxyl terminus (also referred to herein as the "C-terminus"), is almost constant for each class or subclass, and is called the constant region.

[0017] It is known that the variable regions of both the heavy and light chains each contain three complementarity determining regions (CDRs). These complementarity determining regions, also called hypervariable domains, are located within the variable regions of the heavy and light chains of antibodies and exhibit particularly high variability in their primary structure. They are separated into three distinct locations on the primary structure of the heavy and light polypeptide chains. In this specification, the complementarity determining regions of the heavy or light chain of an antibody are denoted as CDR1, CDR2, and CDR3, starting from the amino-terminal side of the amino acid sequence of the heavy or light chain. These regions are in close proximity to each other in terms of their three-dimensional structure and determine the specificity for the antigen they bind to. The portion of the variable region other than the CDRs is called the framework region (FR), consisting of FR1 to FR4, and exhibits relatively little change in its amino acid sequence.

[0018] In this specification, the term "antibody" is used in its broadest sense unless specifically limited by context, and may encompass polypeptides of various structures and properties. For example, it may be a polypeptide that specifically binds to an antigen, such as immunoglobulins, IgG antibodies, monoclonal antibodies, polyclonal antibodies, multispecific antibodies (e.g., bispecific antibodies, tripspecific antibodies), or antigen-binding fragments.

[0019] In this specification, the term "antigen" is used in its commonly used sense to represent a molecule or part of a molecule to which an antibody can specifically bind. Antigens can be molecules such as proteins and nucleic acids. A single antigen may have one or more epitopes that can interact with different antibodies, etc. Useful antigens may be found, for example, on the surface of cells (e.g., tumor cells, virus-infected cells, other diseased cells, immune cells) or as free entities in serum, the extracellular matrix (ECM), etc. In this specification, a protein referred to as an antigen (e.g., GPRC5A) may be a protein derived from any vertebrate, including mammals such as primates (e.g., humans), non-human primates (e.g., cynomolgus monkeys), and rodents (e.g., mice and rats), unless otherwise specified. In one embodiment, the antigen is a human-derived protein.

[0020] In this specification, "IgG antibody" means an antibody having a Y-shaped structure consisting of two Fab regions and an Fc region. That is, an IgG antibody has a structure consisting of two heavy chains and two light chains. In one embodiment, the two Fab regions of the IgG antibody contain the same VH and VL sequences. In one embodiment, the two Fab regions of the IgG antibody may contain different VH and VL sequences.

[0021] In this specification, "monoclonal antibody" means an antibody obtained from a substantially homogeneous population of antibodies. Essentially, the individual antibodies constituting the population are identical and bind to the same epitope. For example, monoclonal antibodies used in accordance with the present invention can be produced by various techniques, such as hybridoma generation, recombinant DNA generation, phage display, or by using transgenic animals containing all or part of a human immunoglobulin locus.

[0022] In this specification, "human antibody" refers to an antibody having a human immunoglobulin amino acid sequence. In this specification, "fully human antibody" refers to an antibody consisting solely of a human immunoglobulin amino acid sequence. In this specification, "human chimeric antibody" refers to an antibody having the antigen-binding variable region of a mouse immunoglobulin amino acid sequence and the constant region of a human immunoglobulin amino acid sequence. In this specification, "humanized antibody" refers to an antibody having the CDR region of a mouse immunoglobulin amino acid sequence and the framework region and constant region of a human immunoglobulin amino acid sequence.

[0023] In this specification, "antigen-binding fragment" refers to a molecule that includes the heavy chain variable region and light chain variable region of an immunoglobulin molecule and contains at least one polypeptide chain having antigen-binding activity. Representative antigen-binding fragments include single-chain variable region fragments (scFv), Fab fragments, Fab' fragments, and F(ab')2 fragments. scFv is a monovalent antigen-binding fragment composed of VH and VL linked by a linker. Fab fragment is a monovalent antigen-binding fragment composed of a light chain and a fragment containing the VH and CH1 domain of the heavy chain. Fab' fragment is a monovalent antigen-binding fragment composed of a light chain and a fragment containing the VH and CH1 domain of the heavy chain and a portion of the hinge region, the hinge region containing cysteine ​​residues that constituted the S-S bond between the heavy chains. F(ab')2 fragment is a divalent molecule in which the Fab' fragment is linked by a disulfide bond. Monovalent means containing one antigen-binding site, while bivalent means containing two antigen-binding sites. Furthermore, Fab fragments, Fab' fragments, and F(ab')2 fragments may also include fragments in which the heavy chain VH1 and CH1, and the light chain VL and CL are crossed over, respectively (mAbs, 2016, 8:1010-1020).

[0024] In this specification, "specifically binding" means exhibiting binding activity only when the antigen is expressed. For example, "specifically binding to GPRC5A" means that when measured using a method commonly used by those skilled in the art, such as the flow cytometry method described in Example 1 or the Enzyme-Linked ImmunoSorbent Assay (ELISA) method, it exhibits strong binding activity to cells expressing GPRC5A. In one embodiment, "specifically binding" means exhibiting a binding activity of two times or more. In one embodiment, "specifically binding" means preferably exhibiting a binding activity of five times or more, and more preferably ten times or more.

[0025] In this specification, "antibody-drug conjugate (ADC)" refers to a drug having pharmacological activity attached to an antibody that binds to an antigen.

[0026] In this specification, "multispecific antibody" refers to an antibody that can specifically bind to two or more different antigens, and is called, for example, a bispecific antibody, triplicate antibody, or quadruplicate antibody depending on the number of antigens it binds to. A multispecific antibody is composed of two or more antibodies and / or antigen-binding fragments, each capable of binding to a different antigen.

[0027] The amino acid residue numbers of antibodies used herein can be specified according to the Kabat numbering or EU index (Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed., 1991, NIH Publication: No. 91-3242), by designating these numbering systems.

[0028] In this specification, “Subject” means a human or other animal requiring detection, diagnosis, prevention, or treatment of a disease. In one embodiment, the subject is a human requiring detection, diagnosis, prevention, or treatment of a disease. In one embodiment, the subject is a human requiring detection, diagnosis, prevention, or treatment of an autoimmune disease, cancer, etc.

[0029] In this specification, “treatment” means any intervention or procedure performed on a subject for the purpose of restoring, alleviating, improving, suppressing or delaying the progression, onset, worsening, or recurrence of the symptoms, condition, or biochemical signs associated with the disease, and includes the administration of physiologically active substances such as antibodies, complexes, ADCs, pharmaceutical compositions, etc., to the subject.

[0030] In this specification, "pharmaceutical composition" means a drug containing an active ingredient and pharmaceutically acceptable excipients (including, but not limited to, pharmaceutical excipients and pharmaceutical carriers) that is prescribed for the purpose of prevention or treatment of a target.

[0031] <Anti-GPRC5A Antibody of the Present Invention> In this specification, "anti-GPRC5A antibody" refers to an antibody capable of binding to human GPRC5A. Whether or not it binds to human GPRC5A can be confirmed using known binding activity measurement methods. As a method for measuring binding activity, for example, methods commonly used by those skilled in the art, such as the flow cytometry method or the Enzyme-Linked ImmunoSorbent Assay (ELISA) method described in Example 1, can be used.

[0032] The anti-GPRC5A antibody and / or its antigen-binding fragment provided by the present invention may collectively be referred to as "the anti-GPRC5A antibody of the present invention."

[0033] The present invention provides an anti-GPRC5A antibody or its antigen-binding fragment comprising a heavy chain variable region and a light chain variable region as described in any of (a) to (n) below: (a) a heavy chain variable region comprising CDR1 consisting of the amino acid sequence of amino acids 31 to 35 of SEQ ID NO: 3, CDR2 consisting of the amino acid sequence of amino acids 50 to 66 of SEQ ID NO: 3, and CDR3 consisting of the amino acid sequence of amino acids 99 to 106 of SEQ ID NO: 3; and a light chain variable region comprising CDR1 consisting of the amino acid sequence of amino acids 24 to 34 of SEQ ID NO: 4, CDR2 consisting of the amino acid sequence of amino acids 50 to 56 of SEQ ID NO: 4, and CDR3 consisting of the amino acid sequence of amino acids 89 to 97 of SEQ ID NO: 4; (b) A heavy chain variable region including CDR1 consisting of the amino acid sequence of amino acids 31 to 35 of SEQ ID NO: 5, CDR2 consisting of the amino acid sequence of amino acids 50 to 66 of SEQ ID NO: 5, and CDR3 consisting of the amino acid sequence of amino acids 99 to 113 of SEQ ID NO: 5, and a light chain variable region including CDR1 consisting of the amino acid sequence of amino acids 24 to 34 of SEQ ID NO: 6, CDR2 consisting of the amino acid sequence of amino acids 50 to 56 of SEQ ID NO: 6, and CDR3 consisting of the amino acid sequence of amino acids 89 to 97 of SEQ ID NO: 6; (c) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 7, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 7, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 108 of SEQ ID NO: 7; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 8, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 8, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 8;(d) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 9, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 9, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 108 of SEQ ID NO: 9, and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 10, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 10, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 10; (e) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 11, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 11, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 109 of SEQ ID NO: 11; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 34 of SEQ ID NO: 12, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 56 of SEQ ID NO: 12, and CDR3 consisting of amino acid sequences from amino acid numbers 89 to 97 of SEQ ID NO: 12; (f) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 13, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 13, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 112 of SEQ ID NO: 13; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 14, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 14, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 14;(g) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 15, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 15, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 108 of SEQ ID NO: 15; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 16, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 16, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 16; (h) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 17, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 17, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 17; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 18, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 18, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 18; and (i) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 19, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 19, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 109 of SEQ ID NO: 19; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 34 of SEQ ID NO: 20, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 56 of SEQ ID NO: 20, and CDR3 consisting of amino acid sequences from amino acid numbers 89 to 97 of SEQ ID NO: 20;and (j) a heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 39, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 39, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 39, and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 40, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 40, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 40; and (k) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 41, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 41, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 41; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 42, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 42, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 42; and (l) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 43, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 43, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 43; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 44, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 44, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 44;and (m) a heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 45, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 45, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 45, and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 46, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 46, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 46; and (n) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 47, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 47, and CDR3 consisting of amino acid sequences 99 to 109 of SEQ ID NO: 47; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 48, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 48, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 48.

[0034] In one embodiment, the anti-GPRC5A antibody or antigen-binding fragment of the present invention is an anti-GPRC5A antibody or antigen-binding fragment comprising a heavy chain variable region and a light chain variable region as described in any of (a) to (n) below: (a) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 3, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 4; (b) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 5, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 6; (c) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 7, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 8; (d) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 9, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 10; (e) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 11, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 12; (f) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 13, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 14; (g) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 15, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 16; (h) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 17, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 18; and (i) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 19, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 20; and (j) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 39, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 40; and (k) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 41, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 42; and (l) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 43, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 44; and (m) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 45, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 46; and (n) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 47, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 48.

[0035] In one embodiment, the antigen-binding fragment of the present invention is scFv, Fab, Fab', or F(ab')2.

[0036] The heavy chain constant region included in the anti-GPRC5A antibody or its antigen-binding fragment of the present invention can be selected from any of the constant regions of Igγ, Igμ, Igα, Igδ, or Igε. For example, Igγ can be selected from Igγ1, Igγ2, Igγ3, or Igγ4. The light chain constant region included in the anti-GPRC5A antibody or its antigen-binding fragment of the present invention can be selected from any of the constant regions of Igλ or Igκ. In one embodiment, the heavy chain constant region and the light chain constant region of the anti-GPRC5A antibody or its antigen-binding fragment are the constant regions of human Igγ1 and Igκ, respectively.

[0037] In one embodiment, the anti-GPRC5A antibody of the present invention is an IgG1 antibody, an IgG2 antibody, an IgG3 antibody, or an IgG4 antibody. In one embodiment, the anti-GPRC5A antibody of the present invention is an IgG1 antibody.

[0038] The anti-GPRC5A antibody of the present invention may contain mutations that reduce antibody-dependent cell-mediated cytotoxicity (ADCC) or complement-dependent cytotoxicity (CDC). L234A is a substitution of leucine to alanine at amino acid position 234 of the human Igγ1 constant region. L235A is a substitution of leucine to alanine at amino acid position 235 of the human Igγ1 constant region. Amino acid mutations in the human Igγ1 constant region L234A and L235A are called "LALA mutations". These mutations are known to reduce the ADCC and CDC of antibodies (Mol. Immunol., 1992, 29:633-639; J. Immunol., 2000, 164:4178-4184). P331G or P331S is a substitution of proline to glycine or serine at amino acid position 331 of the human Igγ1 constant region. This mutation is known to reduce the CDC of antibodies (J. Immunol., 2000, 164:4178-4184).

[0039] In one embodiment, the anti-GPRC5A antibody of the present invention contains L234A and L235A amino acid mutations (LALA mutations) in its heavy chain. In one embodiment, the anti-GPRC5A antibody of the present invention contains either the P331G or P331S mutation in its heavy chain. In one embodiment, the anti-GPRC5A antibody of the present invention contains the LALA mutation and either the P331G or P331S mutation in its heavy chain.

[0040] In this specification, descriptions of amino acid mutations such as LALA mutations, P331G mutations, or P331S mutations are based on the amino acid positions in the human Igγ1 constant region according to the EU index. For example, as mentioned above, L234A is a substitution of leucine to alanine at amino acid position 234 in the human Igγ1 constant region according to the EU index.

[0041] The anti-GPRC5A antibody of the present invention may contain mutations based on other known techniques. For example, a mutation from asparagine to glycine at position 297 (N297G mutation) has been shown to result in non-glycosylation, improving purification efficiency and physical properties (Protein Cell, 2018, 9:63-73).

[0042] The antibody or antigen-binding fragment used in the present invention may have any amino acid residue substituted with cysteine ​​or a non-natural amino acid. For substitution with cysteine, for example, the methods described in WO2008 / 141044 and WO2016 / 040856 can be used. For substitution with a non-natural amino acid, for example, the methods described in WO2010 / 081111 and WO2013 / 185115 can be used.

[0043] The anti-GPRC5A antibody of the present invention may further contain mutations used in the production of multi-characteristic antibodies, such as mutations based on the Knobs-into-Holes (kih) technology (hereinafter also referred to as "Knobs-into-Holes mutations") (Nature, 1994, 372:379-383; Nature Biotech., 1998, 16:677-681).

[0044] The anti-GPRC5A antibody or its antigen-binding fragment of the present invention also includes antibodies or its antigen-binding fragment that bind to GPRC5A derived from mice, monkeys, and / or rats, hamsters, guinea pigs, rabbits, and dogs, in addition to binding to human GPRC5A. In one embodiment, the anti-GPRC5A antibody or its antigen-binding fragment of the present invention is an antibody or its antigen-binding fragment that binds to GPRC5A of humans, mice, monkeys, and / or rats, hamsters, guinea pigs, rabbits, and dogs. In one embodiment, the anti-GPRC5A antibody or its antigen-binding fragment of the present invention binds to human GPRC5A (gene number: NP_003970.1) and Macaca fascicularis GPRC5A (gene number: XP_045220710.2). In one embodiment, the anti-GPRC5A antibody or its antigen-binding fragment of the present invention binds to human GPRC5A. The binding of various GPRC5A molecules can be confirmed using known methods for measuring binding activity. Examples of methods for measuring binding activity include ELISA and flow cytometry.

[0045] In this specification, "post-translational modification" refers to modifications that antibodies expressed in cells undergo after translation. Examples of post-translational modifications include the addition of N-linked or O-linked glycans, N-terminal or C-terminal processing, deamidation, aspartic acid isomerization, and methionine oxidation. Such post-translational modifications are known to occur in various antibodies (J. Pharma Sci., 2008, 97:2426-2447).

[0046] In one embodiment, the anti-GPRC5A antibody or its antigen-binding fragment of the present invention may be post-translationally modified. In one embodiment, the post-translational modification is the addition of an N-linked or O-linked glycan, N-terminal or C-terminal processing, deamidation, aspartic acid isomerization, and / or methionine oxidation.

[0047] The anti-GPRC5A antibody or its antigen-binding fragment of the present invention can be readily produced by those skilled in the art using methods known in the art, based on the sequence information of the heavy chain variable region and light chain variable region of the anti-GPRC5A antibody disclosed herein. The anti-GPRC5A antibody or its antigen-binding fragment of the present invention can be produced, for example, by following the method described below in "Method for Producing the Anti-GPRC5A Antibody of the Present Invention".

[0048] <The complex of the present invention, and cells displaying the anti-GPRC5A antibody or its antigen-binding fragment on the cell surface of the present invention> The present invention also provides a complex (also referred to as "the complex of the present invention") in which a peptide component other than GPRC5A (e.g., protein (including antibody), polypeptide) or a non-peptide component (e.g., carbohydrate, lipid, metal (including radioisotopes), organic compound (including toxins, near-infrared fluorescent dyes, chelating agents), etc.) is linked to the anti-GPRC5A antibody or its antigen-binding fragment of the present invention.

[0049] In this specification, "component" means a peptide or non-peptide substance that can be directly bound to an antibody or its antigen-binding fragment, or via a linker or the like.

[0050] The peptide components of the complex of the present invention can be proteins or polypeptides. The proteins or polypeptides are not particularly limited, and for example, antibodies, antigen-binding fragments, ligands, receptors, cytokines, chemokines, growth factors, physiologically active substances, human serum albumin, various tag peptides, artificial helix motif peptides, maltose-binding proteins, glutathione S-transferase, and other peptides or proteins that can promote polymerization can be used.

[0051] In one embodiment, the complex of the present invention may be formed in which a protein or polypeptide is linked to the anti-GPRC5A antibody of the present invention or its antigen-binding fragment via a linker (e.g., a peptide linker). In one embodiment, the protein or polypeptide used in the complex of the present invention may be a polypeptide that binds to or activates or inactivates cells such as immune cells, epithelial cells, fibroblasts, etc., including T cells, B cells, natural killer (NK) cells, dendritic cells, granulocytes, macrophages, mast cells, etc. In this case, the protein or polypeptide used in the complex of the present invention may be directly linked to the anti-GPRC5A antibody of the present invention or its antigen-binding fragment, or it may be linked via any linker (e.g., a peptide linker).

[0052] In one embodiment, the complex of the present invention may be a multispecific antibody in which another antibody is further bound to the anti-GPRC5A antibody of the present invention. In one embodiment, the complex of the present invention may be a multispecific antibody containing the anti-GPRC5A antibody. In one embodiment, the complex of the present invention may be a bispecific antibody containing the anti-GPRC5A antibody of the present invention.

[0053] Furthermore, the non-peptide components used in the complex of the present invention are not particularly limited, and for example, polyethylene glycol, sugar chains, phospholipids, radioisotopes (e.g., zirconium-89 (89Zr), yttrium-90 (90Y), indium-111 (111In), astatine-211 (211At), actinium-225 (225Ac), organic compounds (e.g., cytotoxic agents, molecular targeted drugs), toxins, near-infrared fluorescent dyes (e.g., IRDye®), chelating agents, etc. The substance used in the complex may be directly bound to the anti-GPRC5A antibody of the present invention or its antigen-binding fragment, or it may be bound via any linker. In one embodiment, the complex of the present invention is an antibody-drug conjugate in which a drug is bound to the anti-GPRC5A antibody or its antigen-binding fragment. The conjugate (ADC) is used. The drugs and linkers used in the ADC can be selected from among drugs and linkers commonly used by those skilled in the art. Furthermore, when the anti-GPRC5A antibody or its antigen-binding fragment of the present invention is used in the ADC, the number and type of drugs are not limited, and one or more drugs may be bound. In one embodiment, the conjugate of the present invention is a radioisotope-labeled antibody in which a radioisotope is bound to the anti-GPRC5A antibody or its antigen-binding fragment.

[0054] The complex of the present invention can also be used for the detection of GPRC5A in biological samples or in living organisms. In this specification, "detection" includes quantitative or qualitative detection. In one embodiment, the complex of the present invention can be used for the detection of GPRC5A in biological samples.

[0055] The present invention also provides cells (e.g., chemotherapy antigen receptor-T cells: CAR-T cells) ("presenting cells of the present invention") in which the anti-GPRC5A antibody or its antigen-binding fragment of the present invention is displayed on the surface of cells (e.g., immune cells such as T cells, NK cells, and macrophages). The method for producing presenting cells of the present invention is not particularly limited, but for example, they can be produced by expressing the anti-GPRC5A antibody or its antigen-binding fragment on the cell surface using a polynucleotide encoding the anti-GPRC5A antibody or its antigen-binding fragment of the present invention.

[0056] In this specification, the complex of the present invention and the presenting cells of the present invention are collectively referred to as "the complex of the present invention, etc."

[0057] In one embodiment, the antibody or antigen-binding fragment used in the complex of the present invention may be post-translation modified. In one embodiment, the post-translation modification is the addition of an N-linked or O-linked glycan, processing of the N-terminus or C-terminus, deamidation, isomerization of aspartic acid, and / or oxidation of methionine.

[0058] The anti-GPRC5A antibody or its antigen-binding fragment, the complex of the present invention, etc., can be readily produced by those skilled in the art using methods known in the art, based on the VH and VL sequence information of the anti-GPRC5A antibody or its antigen-binding fragment disclosed herein, other peptides or proteins (e.g., antibodies) used in the complex of the present invention, and information on modifiers used in the complex of the present invention. The anti-GPRC5A antibody or its antigen-binding fragment of the present invention can be produced, for example, by the method described in the section "Method for Producing the Anti-GPRC5A Antibody of the Present Invention."

[0059] <Anti-GPRC5A Antibody-Drug Conjugate of the Present Invention> The present invention also provides an anti-GPRC5A antibody-drug conjugate for delivering a drug to target cells. The anti-GPRC5A drug conjugate of the present invention (hereinafter also referred to as "the anti-GPRC5A antibody-drug conjugate of the present invention") can be produced by conjugating a drug to the anti-GPRC5A antibody or its antigen-binding fragment via a linker. In one embodiment, the anti-GPRC5A antibody-drug conjugate of the present invention has a drug conjugated to the anti-GPRC5A antibody or its antigen-binding fragment via a linker. The anti-GPRC5A antibody-drug conjugate of the present invention specifically binds to the antigen GPRC5A, and the antibody-drug conjugate is taken up into the cell upon internalization of GPRC5A. Subsequently, some or all of the linkers in the conjugate are cleaved within the cell, releasing the drug and exerting its pharmacological effect.

[0060] In one embodiment, the anti-GPRC5A antibody-drug conjugate of the present invention comprises a conjugate represented by the following formula (I) or a pharmaceutically acceptable salt or solvate: Ab-(L １ -D １ n １１ -D ２ n １２ ―…-D ｐ n １Ｎ )m １ - (L ２ -D １ n ２１ ―D ２ n ２２ ―…-D ｐ n ２Ｎ )m ２ -...- (L Ｋ -D １ n Ｋ１ ―D ２ n Ｋ２ ―…-D ｐ n ＫＮ )m ｋ (I) In formula (I), Ab is an antibody, that is, the anti-GPRC5A antibody of the present invention or its antigen-binding fragment, and D １ ~D ｐ It is a drug, L １ ~L Ｋ is a linker, n １１ ~n ＫＮ , m１ ~m ｋ Each of these is an arbitrary integer greater than or equal to 0. Furthermore, the drug and the linker may be the same or different.

[0061] 1. Antibody or its antigen-binding fragment (Ab) The antibody or its antigen-binding fragment used in the anti-GPRC5A antibody-drug conjugate of the present invention may have any amino acid sequence as long as it specifically binds to GPRC5A and is internalized within the cell.

[0062] In one embodiment, the antibody or antigen-binding fragment used in the anti-GPRC5A antibody-drug conjugate of the present invention is an anti-GPRC5A antibody or antigen-binding fragment comprising a heavy chain variable region and a light chain variable region as described in any of (a) to (n) below: (a) a heavy chain variable region comprising CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 3, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 3, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 3, and a light chain variable region comprising CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 4, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 4, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 4; (b) A heavy chain variable region including CDR1 consisting of the amino acid sequence of amino acids 31 to 35 of SEQ ID NO: 5, CDR2 consisting of the amino acid sequence of amino acids 50 to 66 of SEQ ID NO: 5, and CDR3 consisting of the amino acid sequence of amino acids 99 to 113 of SEQ ID NO: 5, and a light chain variable region including CDR1 consisting of the amino acid sequence of amino acids 24 to 34 of SEQ ID NO: 6, CDR2 consisting of the amino acid sequence of amino acids 50 to 56 of SEQ ID NO: 6, and CDR3 consisting of the amino acid sequence of amino acids 89 to 97 of SEQ ID NO: 6; (c) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 7, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 7, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 108 of SEQ ID NO: 7; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 8, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 8, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 8;(d) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 9, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 9, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 108 of SEQ ID NO: 9, and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 10, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 10, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 10; (e) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 11, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 11, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 109 of SEQ ID NO: 11; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 34 of SEQ ID NO: 12, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 56 of SEQ ID NO: 12, and CDR3 consisting of amino acid sequences from amino acid numbers 89 to 97 of SEQ ID NO: 12; (f) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 13, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 13, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 112 of SEQ ID NO: 13; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 14, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 14, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 14;(g) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 15, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 15, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 108 of SEQ ID NO: 15; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 16, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 16, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 16; (h) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 17, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 17, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 17; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 18, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 18, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 18; and (i) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 19, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 19, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 109 of SEQ ID NO: 19; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 34 of SEQ ID NO: 20, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 56 of SEQ ID NO: 20, and CDR3 consisting of amino acid sequences from amino acid numbers 89 to 97 of SEQ ID NO: 20;and (j) a heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 39, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 39, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 39, and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 40, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 40, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 40; and (k) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 41, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 41, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 41; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 42, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 42, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 42; and (l) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 43, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 43, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 43; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 44, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 44, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 44;and (m) a heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 45, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 45, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 45, and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 46, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 46, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 46; and (n) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 47, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 47, and CDR3 consisting of amino acid sequences 99 to 109 of SEQ ID NO: 47; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 48, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 48, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 48.

[0063] In one embodiment, the antibody or antigen-binding fragment used in the anti-GPRC5A antibody-drug conjugate of the present invention is an anti-GPRC5A antibody or antigen-binding fragment comprising a heavy chain variable region and a light chain variable region as described in any of (a) to (n) below: (a) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 3, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 4; (b) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 5, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 6; (c) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 7, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 8; (d) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 9, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 10; (e) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 11, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 12; (f) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 13, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 14; (g) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 15, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 16; (h) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 17, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 18; and (i) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 19, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 20; and (j) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 39, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 40; and (k) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 41, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 42; and (l) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 43, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 44; and (m) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 45, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 46; and (n) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 47, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 48.

[0064] In one embodiment, the antibody used in the anti-GPRC5A antibody-drug conjugate of the present invention is IgG. In one embodiment, the antibody used in the anti-GPRC5A antibody-drug conjugate of the present invention is IgG1 antibody or IgG4 antibody. In one embodiment, the antibody used in the anti-GPRC5A antibody-drug conjugate of the present invention is IgG1 antibody.

[0065] The antibody or its antigen-binding fragment used in the anti-GPRC5A antibody-drug conjugate of the present invention may be post-translationally modified. Furthermore, amino acid substitutions may be made at any amino acid site for the purpose of regulating ADCC or CDC activity or introducing cysteine ​​residues.

[0066] 2. Drugs (D) There are no particular restrictions on the drugs used in antibody-drug conjugates, as long as they have a structure that can bind to the linker. Drugs used in antibody-drug conjugates may have diverse pharmacological activities, and examples include cytotoxic agents, immunoactivators, targeted protein degradation inducers (PROTACs), and molecularly targeted drugs. Anti-GPRC5A antibody-drug conjugates can be used to treat various diseases depending on the drug they bind to.

[0067] Examples of cytotoxic agents include microtubule polymerization inhibitors and DNA inhibitors (DNA damage agents, topoisomerase I inhibitors).

[0068] Examples of microtubule polymerization inhibitors include maytansinoids such as DM1 and DM4.

[0069] Furthermore, microtubule polymerization inhibitors include auristatins such as monomethyl auristatin E (MMAE) and monomethyl auristatin F (MMAF), and auristatins are, for example, represented by the following formula (IIa) or (IIb): (IIa) This is a compound represented by (IIb). The wavy lines in the formula indicate bonds.

[0070] Examples of microtubule polymerization inhibitors include eribulin, tubulinin, cryptophycin, SB-715992 (ispinesib), and EG5 inhibitors such as filanesib.

[0071] Examples of DNA inhibitors include engine compounds such as calicheamycin and unciaramycin.

[0072] Furthermore, DNA inhibitors include, for example, topoisomerase I inhibitors such as topotecan, camptothecin, SN-38, govitecan, exatecan, or exatecan derivative DXd, and topoisomerase I inhibitors are represented by, for example, the following formula (IIIa) or (IIIb): (IIIa) This is a compound represented by (IIIb). The wavy lines in the formula indicate bonds.

[0073] Examples of DNA inhibitors include DNA alkylating agents such as Pyrrolo[2,1-c][1,4]benzodiazepines (PBD), duocamycin A, and CC-1065.

[0074] Examples of immunoactivators that can be used include Toll-like receptor (TLR) 7, TLR8, TLR7 / 8, TLR9 agonists, stimulator of interferon genes (STING) agonists, and Glucocorticoid receptor modulators (GRMs) (Acta Pharma. Sin. B, Vol. 13(10): pp. 4025-4059).

[0075] The number and types of drugs that bind to the anti-GPRC5A antibody are not particularly limited, and multiple numbers or multiple types of drugs may be bound to one antibody.

[0076] In one embodiment, the anti-GPRC5A antibody-drug conjugate of the present invention is a conjugate in which one or more drugs selected from cytotoxic agents, immunoactivators, targeted protein degradation-inducing compounds (PROTACs), and molecularly targeted drugs are bound to the anti-GPRC5A antibody of the present invention. In one embodiment, the anti-GPRC5A antibody-drug conjugate of the present invention is a conjugate in which one or more drugs selected from cytotoxic agents and immunoactivators are bound to the anti-GPRC5A antibody of the present invention. In one embodiment, the anti-GPRC5A antibody-drug conjugate of the present invention is a conjugate in which a cytotoxic agent is bound to the anti-GPRC5A antibody of the present invention. In one embodiment, the anti-GPRC5A antibody-drug conjugate of the present invention is a conjugate in which a DNA inhibitor or microtubule polymerization inhibitor is bound to the anti-GPRC5A antibody of the present invention. In one embodiment, the anti-GPRC5A antibody-drug conjugate of the present invention is a conjugate in which one or more cytotoxic agents are bound to the anti-GPRC5A antibody of the present invention. In one embodiment, the anti-GPRC5A antibody-drug conjugate of the present invention is a conjugate in which a microtubule polymerization inhibitor is bound to the anti-GPRC5A antibody of the present invention. In one embodiment, the anti-GPRC5A antibody-drug conjugate of the present invention is a conjugate in which an auristatin-type microtubule polymerization inhibitor is bound to the anti-GPRC5A antibody of the present invention. In one embodiment, the anti-GPRC5A antibody-drug conjugate of the present invention is a conjugate in which MMAE or MMAF is bound to the anti-GPRC5A antibody of the present invention. In one embodiment, the anti-GPRC5A antibody-drug conjugate of the present invention is a conjugate in which MMAE is bound to the anti-GPRC5A antibody of the present invention.

[0077] In one embodiment, the anti-GPRC5A antibody-drug conjugate of the present invention may be an antibody-drug conjugate in which a drug is further conjugated to a multispecific antibody containing an anti-GPRC5A antibody. In one embodiment, the anti-GPRC5A antibody-drug conjugate of the present invention may be a conjugate in which one or more drugs selected from cytotoxic agents, immunoactivators, targeted protein degradation-inducing compounds (PROTACs), and molecularly targeted drugs are further conjugated to a multispecific antibody containing an anti-GPRC5A antibody.

[0078] In antibody-drug conjugates, the number of drug molecules bound to a single antibody molecule is a crucial factor affecting their efficacy and safety. The production of antibody-drug conjugates is carried out by defining reaction conditions, such as the amount of raw materials and reagents used, so that the number of drug molecules bound falls within a certain range. However, unlike the chemical reactions of low-molecular-weight compounds, the resulting product is typically a mixture with varying numbers of drugs bound to it. The number of drug molecules bound to a single antibody molecule is expressed as the Drug-to-Antibody Ratio (DAR). In this specification, the number of drug molecules bound is expressed using the DAR. In one embodiment, the DAR of the anti-GPRC5A antibody-drug conjugate of the present invention is 1 to 10. In one embodiment, the DAR of the anti-GPRC5A antibody-drug conjugate of the present invention is 2 to 8. In one embodiment, the DAR of the anti-GPRC5A antibody-drug conjugate of the present invention is 4 to 6. Furthermore, those skilled in the art can design a reaction to conjugate the required number of drugs to an antibody based on the descriptions of the examples in this application, and obtain an antibody-drug conjugate with a controlled number of drugs.

[0079] 3. Linker (L) Generally, antibody-drug conjugates contain a linker between the antibody and the drug. The linker may or may not be cleavable in the intracellular environment. If the linker is cleavable, the linker portion of the antibody-drug conjugate taken into the cell is cleaved by cleavage enzymes such as proteases and peptidases in lysosomes and endosomes within the cell, releasing the drug into the cell. If the linker of the antibody-drug conjugate taken into the cell is not cleavable, the antibody-drug conjugate taken into the cell is released into the cell by the degradation of the antibody.

[0080] Linkers that can be cleaved can be broadly classified into two types: those cleaved by enzymes, such as peptide-based linkers, β-glucuronide-based linkers, and phosphorate-based linkers, and those cleaved chemically, such as pH-sensitive linkers and glutathione-sensitive linkers.

[0081] Peptide-based linkers are peptides with a length of at least two amino acids. The cleaving enzymes can include cathepsin B, D, and plasmin, which are known to hydrolyze antibody-drug conjugates, releasing the drug into target cells. Examples of peptidyl linkers include the valine-citrulline (Val-Cit) linker, the phenylalanine-leucine (Phe-Leu) linker, the phenylalanine-lysine (Phe-Lys) linker, the valine-alanine (Val-Ala) linker, the cyclobutane-1,1-dicarboxamide-citrulline (cBu-Cit) linker, the glycine-phenylalanine-leucine-glycine (Gly-Phe-Leu-Gly) linker (SEQ ID NO: 37), and, for example, the following formulas (IV), (VII), or (VIII): (IV) (VII) Compounds represented by (VIII) can be used. In the formula, m is the number of [(linker)-(drug)] parts covalently linked to the antibody, D is the drug, Ab is the antibody, and S is the sulfur atom of the antibody.

[0082] β-glucuronide-based linkers are linkers that are recognized and hydrolyzed by β-glucuronidase present in lysosomes. Typical β-glucuronide-based linkers are compounds containing p-aminobenzyl alcohol and β-glucuronide, for example, the following formula (VI): Compounds represented by (VI) can be used. In the formula, m is the number of [(linker)-(drug)] parts covalently linked to the antibody, D is the drug, Ab is the antibody, and S is the sulfur atom of the antibody.

[0083] pH-sensitive linkers, that is, linkers that are sensitive to hydrolysis at a certain pH value, are generally hydrolyzed under acidic conditions. Examples of pH-sensitive linkers that can be hydrolyzed in lysosomes include hydrazones, semicarbazones, thiosemicarbazones, cis-aconitamides, orthoesters, acetals, and ketals. These linkers are relatively stable under neutral pH conditions, such as those in blood, but are unstable below pH 5.5 to 5.0, which is the approximate pH of lysosomes.

[0084] Glutathione-sensitive linkers are linkers that contain molecules that are reduced and cleaved by glutathione in the cell (e.g., disulfide linkers). Various disulfide linkers are known in the art, and include, for example, SATA (N-succinimidyl-S-acetylthioacetate), SPDP (N-succinimidyl-3-(2-pyridyldithio)propionate), SPDB (N-succinimidyl-3-(2-pyridyldithio)butyrate), SMPT (N-succinimidyl-oxycarbonyl-α-methyl-α-(2-pyridyldithio)toluene), and those that can be formed using SPDB and SMPT, etc. (Acta Pharmaceutica Sinica B, 2021, 11(12):p3889-3907, Pharmaceutics, 2022:14(2):396).

[0085] Non-cleavable linkers are known to release drugs into target cells when antibodies are degraded by proteases in the cytoplasm or lysosomes. Examples of non-cleavable linkers include maleimidocaproyl (MC) and succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate (SMCC), for example, in formula (V): Compounds represented by (V) can be used. In the formula, m is the number of [(linker)-(drug)] parts covalently linked to the antibody, D is the drug, Ab is the antibody, and S is the sulfur atom of the antibody.

[0086] In one embodiment, the linker used in the anti-GPRC5A antibody-drug conjugate of the present invention may be a cleavable linker or a non-cleavable linker. In one embodiment, the linker used in the anti-GPRC5A antibody-drug conjugate of the present invention is a cleavable linker. In one embodiment, the linker used in the anti-GPRC5A antibody-drug conjugate of the present invention is a non-cleavable linker.

[0087] In one embodiment, the linker used in the anti-GPRC5A antibody-drug conjugate of the present invention may be any of the following: Val-Cit linker, Phe-Leu linker, Phe-Lys linker, or Gly-Phe-Leu-Gly linker. In one embodiment, the linker used in the anti-GPRC5A antibody-drug conjugate of the present invention is a Val-Cit linker.

[0088] <Anti-GPRC5A multispecific antibody of the present invention> By linking the anti-GPRC5A antibody of the present invention or its antigen-binding fragment to one or more other antibodies or their antigen-binding fragments, a multispecific antibody containing the anti-GPRC5A antibody of the present invention or its antigen-binding fragment (referred to as "the anti-GPRC5A multispecific antibody of the present invention") can be provided.

[0089] The anti-GPRC5A multispecific antibody of the present invention may have any structure as described in the literature (mAbs, 2017, 9:182-212, Fig. 2), for example. In one embodiment, the anti-GPRC5A multispecific antibody of the present invention may have a symmetric or asymmetric structure.

[0090] In one embodiment, the antigen-binding fragment of the anti-GPRC5A antibody of the present invention contained in the anti-GPRC5A multispecific antibody of the present invention may be scFv, Fab, Fab', F(ab')2.

[0091] The anti-GPRC5A multispecific antibody of the present invention can be prepared by a person skilled in the art using methods known in the art, based on the anti-GPRC5A antibody of the present invention or its antigen-binding fragment, and the sequence information of other known antibodies or antigen-binding fragments.

[0092] <Pharmaceutical Compositions of the Present Invention> The pharmaceutical compositions of the present invention include pharmaceutical compositions comprising the anti-GPRC5A antibody of the present invention, its antigen-binding fragment, or the complex of the present invention, etc., and pharmaceutically acceptable excipients (also referred to as "pharmaceutical compositions of the present invention"). The pharmaceutical compositions of the present invention can be prepared by commonly used methods using excipients commonly used in the art, i.e., pharmaceutical excipients and pharmaceutical carriers. Examples of dosage forms of these pharmaceutical compositions include, for example, parenteral preparations such as injections and intravenous infusions, which can be administered by intravenous, subcutaneous, or intramuscular administration. In formulation, excipients, carriers, additives, etc., can be used according to these dosage forms, within a pharmaceutically acceptable range.

[0093] The pharmaceutical compositions of the present invention may include the anti-GPRC5A antibody of the present invention, its antigen-binding fragment, or the complex of the present invention, and post-translational modifications thereof. For example, the present invention also includes pharmaceutical compositions containing antibodies that have undergone addition of N-linked or O-linked glycans, processing of the N-terminus or C-terminus, deamidation, isomerization of aspartic acid, and / or oxidation of methionine.

[0094] The amount of the anti-GPRC5A antibody or its antigen-binding fragment added to the formulation of the present invention varies depending on the severity of the patient's symptoms, age, dosage form of the formulation used, and the antibody's binding titer, but for example, an amount of about 0.0001 mg / kg to 1000 mg / kg can be used. In one embodiment, the amount of the anti-GPRC5A antibody or its antigen-binding fragment added to the formulation of the present invention is 0.0001 mg / kg to 1000 mg / kg, preferably 0.001 mg / kg to 100 mg / kg, and more preferably 0.01 mg / kg to 50 mg / kg.

[0095] <Pharmaceutical Uses of the Anti-GPRC5A Antibody of the Present Invention> The anti-GPRC5A antibody of the present invention, its antigen-binding fragment, or the complex of the present invention, and pharmaceutical compositions containing them, can be used for the detection, diagnosis, prevention, or treatment of diseases such as cancer in cells and tissues expressing GPRC5A.

[0096] In one embodiment, the disease targeted for prevention or treatment according to the present invention is cancer. The cancers targeted for prevention or treatment are not particularly limited, but include, for example, gastric cancer, lung cancer, acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), Hodgkin lymphoma, non-Hodgkin lymphoma, B-cell lymphoma, multiple myeloma, T-cell lymphoma and other hematological cancers, myelodysplastic syndromes, adenocarcinoma, squamous cell carcinoma, adenosquamous cell carcinoma, anaplastic carcinoma, large cell carcinoma, non-small cell lung cancer, small cell lung cancer, mesothelioma, skin cancer, cutaneous T-cell lymphoma, and breast cancer. This includes solid cancers such as cancer, prostate cancer, bladder cancer, vaginal cancer, cervical cancer, head and neck cancer, uterine cancer, cervical cancer, liver cancer, gallbladder cancer, bile duct cancer, kidney cancer, pancreatic cancer, colon cancer, colorectal cancer, rectal cancer, small intestine cancer, stomach cancer, esophageal cancer, testicular cancer, ovarian cancer, and brain tumors, as well as sarcomas such as chondrosarcoma, Ewing's sarcoma, osteosarcoma, and soft tissue sarcoma, and blastomas such as glioblastoma, glioblastoma multiforme, hepatoblastoma, medulloblastoma, nephroblastoma, neuroblastoma, and retinoblastoma.

[0097] Furthermore, the present invention includes a method for preventing or treating diseases such as cancer, comprising the step of administering a target amount effective for detection, diagnosis, prevention, or treatment using the anti-GPRC5A antibody of the present invention, its antigen-binding fragment, and the complex of the present invention. Furthermore, the present invention includes the use of the anti-GPRC5A antibody of the present invention, its antigen-binding fragment, or the complex of the present invention for use in the detection, diagnosis, prevention, or treatment of diseases such as cancer. Furthermore, the present invention includes the use of the anti-GPRC5A antibody of the present invention, its antigen-binding fragment, or the complex of the present invention in the manufacture of pharmaceutical compositions for the detection, diagnosis, prevention, or treatment of diseases such as cancer.

[0098] <Polynucleotides of the Present Invention> The polynucleotides of the present invention include a polynucleotide comprising the anti-GPRC5A antibody of the present invention, a base sequence encoding the heavy chain variable region of its antigen-binding fragment, and a polynucleotide comprising the anti-GPRC5A antibody of the present invention or a base sequence encoding the light chain variable region of its antigen-binding fragment (also referred to as "the polynucleotide of the present invention"). The polynucleotide comprising the base sequence encoding the heavy chain variable region and the polynucleotide comprising the base sequence encoding the light chain variable region may each be contained in a separate polynucleotide or in a single polynucleotide.

[0099] The polynucleotides of the present invention can be readily produced by those skilled in the art using methods known in the art, based on their base sequence. For example, the polynucleotides of the present invention can be synthesized using gene synthesis methods known in the art. Various methods known to those skilled in the art can be used as such gene synthesis methods, such as the method for synthesizing antibody genes described in International Publication No. 90 / 07861.

[0100] In one embodiment, the polynucleotide of the present invention may be an anti-GPRC5A antibody or antigen-binding fragment thereof, comprising a polynucleotide containing a nucleotide sequence encoding a heavy chain variable region as described in any of (a) to (n) below, and a polynucleotide containing a nucleotide sequence encoding a light chain variable region: (a) a heavy chain variable region comprising CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 3, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 3, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 3, and a light chain variable region comprising CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 4, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 4, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 4; (b) A heavy chain variable region including CDR1 consisting of the amino acid sequence of amino acids 31 to 35 of SEQ ID NO: 5, CDR2 consisting of the amino acid sequence of amino acids 50 to 66 of SEQ ID NO: 5, and CDR3 consisting of the amino acid sequence of amino acids 99 to 113 of SEQ ID NO: 5, and a light chain variable region including CDR1 consisting of the amino acid sequence of amino acids 24 to 34 of SEQ ID NO: 6, CDR2 consisting of the amino acid sequence of amino acids 50 to 56 of SEQ ID NO: 6, and CDR3 consisting of the amino acid sequence of amino acids 89 to 97 of SEQ ID NO: 6; (c) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 7, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 7, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 108 of SEQ ID NO: 7; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 8, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 8, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 8;(d) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 9, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 9, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 108 of SEQ ID NO: 9, and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 10, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 10, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 10; (e) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 11, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 11, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 109 of SEQ ID NO: 11; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 34 of SEQ ID NO: 12, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 56 of SEQ ID NO: 12, and CDR3 consisting of amino acid sequences from amino acid numbers 89 to 97 of SEQ ID NO: 12; (f) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 13, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 13, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 112 of SEQ ID NO: 13; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 14, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 14, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 14;(g) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 15, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 15, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 108 of SEQ ID NO: 15; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 16, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 16, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 16; (h) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 17, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 17, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 17; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 18, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 18, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 18; and (i) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 19, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 19, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 109 of SEQ ID NO: 19; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 34 of SEQ ID NO: 20, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 56 of SEQ ID NO: 20, and CDR3 consisting of amino acid sequences from amino acid numbers 89 to 97 of SEQ ID NO: 20;and (j) a heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 39, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 39, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 39, and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 40, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 40, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 40; and (k) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 41, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 41, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 41; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 42, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 42, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 42; and (l) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 43, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 43, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 43; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 44, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 44, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 44;and (m) a heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 45, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 45, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 45, and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 46, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 46, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 46; and (n) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 47, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 47, and CDR3 consisting of amino acid sequences 99 to 109 of SEQ ID NO: 47; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 48, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 48, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 48.

[0101] In one embodiment, the polynucleotide of the present invention may be an anti-GPRC5A antibody or antigen-binding fragment thereof of the present invention, comprising a polynucleotide containing a nucleotide sequence encoding a heavy chain variable region described in any of (a) to (n) below, and a polynucleotide containing a nucleotide sequence encoding a light chain variable region: (a) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 3, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 4; (b) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 5, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 6; (c) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 7, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 8; (d) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 9, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 10; (e) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 11, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 12; (f) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 13, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 14; (g) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 15, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 16; (h) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 17, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 18; and (i) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 19, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 20; and (j) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 39, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 40; and (k) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 41, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 42; and (l) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 43, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 44; and (m) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 45, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 46; and (n) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 47, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 48.

[0102] <Expression Vector of the Present Invention> The expression vector of the present invention includes an expression vector (also referred to as "the expression vector of the present invention") comprising a polynucleotide containing a nucleotide sequence encoding the heavy chain variable region of the anti-GPRC5A antibody of the present invention or its antigen-binding fragment, and / or a polynucleotide containing a nucleotide sequence encoding the light chain variable region of the anti-GPRC5A antibody of the present invention or its antigen-binding fragment.

[0103] In one embodiment, the expression vector of the present invention may be an expression vector comprising a polynucleotide comprising a nucleotide sequence encoding the heavy chain variable region of the anti-GPRC5A antibody of the present invention, an expression vector comprising a polynucleotide comprising a nucleotide sequence encoding the light chain variable region of the anti-GPRC5A antibody of the present invention, or an expression vector comprising a polynucleotide comprising a nucleotide sequence encoding the heavy chain variable region and a polynucleotide comprising a nucleotide sequence encoding the light chain variable region of the anti-GPRC5A antibody of the present invention. In one embodiment, the expression vector of the present invention is an expression vector comprising a polynucleotide comprising a nucleotide sequence encoding the heavy chain variable region of the anti-GPRC5A antibody of the present invention. In one embodiment, the expression vector of the present invention may be an expression vector comprising a polynucleotide comprising a nucleotide sequence encoding the heavy chain variable region and a polynucleotide comprising a nucleotide sequence encoding the light chain variable region of the anti-GPRC5A antibody of the present invention.

[0104] The expression vector of the present invention is not particularly limited as long as it can express polynucleotides in various host cells such as eukaryotic cells (e.g., animal cells, insect cells) and prokaryotic cells (e.g., Escherichia coli) and produce polypeptides encoded therein. Examples of such expression vectors include plasmid vectors and viral vectors (e.g., adenoviruses, retroviruses), and for example, pcDNA3.4 TOPO vector, pcDNA3.1(+) vector, pEE6.4, and pEE12.4 can be used. Furthermore, antibody genes can also be expressed by introducing variable region gene fragments into expression vectors that already have human Ig constant region genes, such as the pFUSEss-CHIg-hG1 vector and the pFUSE2ss-CLIG-hk vector (InvivoGen), and AG-γ1 and AG-κ (see, for example, International Publication No. 94 / 20632).

[0105] The expression vector of the present invention may include a promoter functionally linked to the polynucleotide of the present invention. Examples of promoters for expressing the polynucleotide of the present invention in animal cells include virus-derived promoters such as CMV, RSV, and SV40, actin promoters, EF (elogenation factor) 1α promoters, and heat shock promoters. Examples of promoters for expression in bacteria (e.g., Escherichia species) include trp promoters, lac promoters, λPL promoters, and tac promoters. Examples of promoters for expression in yeast include GAL1 promoters, GAL10 promoters, PH05 promoters, PGK promoters, GAP promoters, and ADH promoters.

[0106] When using animal cells, insect cells, etc., as host cells, the expression vector of the present invention may include a start codon and a stop codon. In this case, the expression vector of the present invention may also include an enhancer sequence, the 5' and 3' untranslated regions of a gene encoding the antibody of the present invention or its heavy chain variable region or light chain variable region, a secretory signal sequence, a splicing junction, a polyadenylation site, or a repeatable unit. When using Escherichia coli as host cells, the expression vector of the present invention may include a start codon, a stop codon, a terminator region, and a repeatable unit. In this case, the expression vector of the present invention may also include a selection marker commonly used depending on the purpose (e.g., a tetracycline resistance gene, an ampicillin resistance gene, a kanamycin resistance gene, a neomycin resistance gene, a dihydrofolate reductase gene).

[0107] <Host Cells of the Invention> The present invention also provides host cells transformed with the polynucleotides of the present invention or the expression vectors of the present invention (collectively referred to as "polynucleotides, etc." of the present invention). The host cells of the present invention contain the polynucleotides, etc. of the present invention within the cell. The introduced polynucleotides, etc. of the present invention may or may not be incorporated into the genomic DNA of the host cell. The host cells may be cells that can be cultured in vitro or cells that are living organisms. If the host cells are cells that can be cultured in vitro, the host cells of the present invention can be produced by introducing the polynucleotides, etc. of the present invention into the cells in vitro. The method for transforming the host cells is not particularly limited, but for example, methods commonly used by those skilled in the art, such as the calcium phosphate method, the electroporation method, or the lipofection method, can be used. If the host cells are cells that are living organisms, the method for introducing the polynucleotides, etc. of the present invention into the host cells is not particularly limited, but nucleic acid delivery carriers (cationic carriers or non-cationic carriers (including, but not limited to, liposomes and lipid nanoparticles (LNPs))) can be used.

[0108] Cells that can be cultured in vitro are not particularly limited as long as they can be transformed by the expression vector used or by methods such as electroporation and express antibodies or polypeptides. Examples of cells that can be cultured in vitro include various cells that are commonly used in the art of the present invention (e.g., animal cells (e.g., CHO-K1 cells, ExpiCHO-S® cells, CHOK1SV cells, CHO-DG44 cells, HEK293 cells, Expi293F cells, NS0 cells), insect cells (e.g., Sf9), bacteria (Escherichia species, etc.)). In one embodiment, the host cells of the present invention are CHO-K1 cells or ExpiCHO-S cells. Selection of host cells transformed in vitro can be carried out by methods commonly used by those skilled in the art. Selection methods may include, for example, drug selection methods using drug selection marker genes and drugs such as tetracycline, ampicillin, neomycin, and zeosin, as well as cell isolation methods such as ultradilution, single-cell sorting, or colony pickup.

[0109] In one embodiment, the host cell of the present invention is a host cell comprising a polynucleotide containing a nucleotide sequence encoding the heavy chain variable region of the anti-GPRC5A antibody of the present invention, and a host cell comprising a polynucleotide containing a nucleotide sequence encoding the light chain variable region of the anti-GPRC5A antibody of the present invention. In one embodiment, the host cell of the present invention is a host cell comprising a polynucleotide containing a nucleotide sequence encoding the heavy chain variable region of the anti-GPRC5A antibody of the present invention and a polynucleotide containing a nucleotide sequence encoding the light chain variable region.

[0110] <Method for Producing the Anti-GPRC5A Antibody of the Present Invention> The present invention also provides a method for producing the anti-GPRC5A antibody or its antigen-binding fragment (also referred to as "the production method of the present invention"). The production method of the present invention may include the aforementioned polynucleotide of the present invention, the expression vector of the present invention, and the method for producing the host cells of the present invention. Furthermore, the production method of the present invention may include the steps of culturing the host cells described in <Transformed Host Cells of the Present Invention> above and expressing the antibody in the cells or the culture supernatant, and the steps of recovering, isolating, and purifying the antibody. However, the production method of the present invention is not limited to these methods, as long as the anti-GPRC5A antibody or its antigen-binding fragment of the present invention is produced.

[0111] In one embodiment, the production method of the present invention includes the step of culturing a host cell containing a polynucleotide comprising a nucleotide sequence encoding the heavy chain variable region of the anti-GPRC5A antibody or its antigen-binding fragment, and a polynucleotide comprising a nucleotide sequence encoding the light chain variable region of the antibody or its antigen-binding fragment, thereby expressing the anti-GPRC5A antibody.

[0112] Transformed host cells can be cultured by known methods. Culture conditions such as temperature, pH of the medium, and culture time can be selected as appropriate. When the host cells are animal cells, known media such as MEM medium, DMEM medium, RPMI1640 medium containing about 5-20% fetal bovine serum, or serum-free ExpiCHO Expression Medium can be used as the culture medium. The pH of the medium is preferably about 6-8, and the culture is usually carried out at about 30-40°C for about 15-336 hours, with aeration and stirring as necessary. By culturing as described above, the anti-GPRC5A antibody of the present invention or its antigen-binding fragment can be expressed.

[0113] The production method of the present invention may further include, in addition to the step of culturing transformed host cells of the present invention and expressing an anti-GPRC5A antibody or its antigen-binding fragment, a step of recovering, for example, isolating or purifying the anti-GPRC5A antibody or its antigen-binding fragment from the transformed host cells. Examples of isolation or purification methods include methods utilizing solubility, differences in molecular weight, charges, specific affinity, differences in hydrophobicity, and differences in isoelectric points. Those skilled in the art can use these methods to purify the anti-GPRC5A antibody or its antigen-binding fragment from the culture supernatant of host cells. In one embodiment, the antibody accumulated in the culture supernatant can be purified by various types of chromatography, for example, column chromatography using a protein A column or a protein G column.

[0114] The anti-GPRC5A antibody or its antigen-binding fragment of the present invention also includes the anti-GPRC5A antibody or its antigen-binding fragment produced by the production method of the present invention.

[0115] Specific examples are provided herein for reference to further understand the present invention, but these are for illustrative purposes only and do not limit the invention.

[0116] (Example 1) Production of mouse anti-GPRC5A antibody 1-1 Production of a cell line that stably expresses human GPRC5A protein A cDNA encoding the human GPRC5A protein, consisting of the amino acid sequence shown in Sequence ID No. 1, was inserted into a pcDNA3.1(+) vector (V79020, Themo Fisher Scientific) to produce a human GPRC5A expression vector, pcDNA3.1-hGPRC5A (hereinafter referred to as "pcDNA3.1-hGPRC5A"). Chinese hamster ovary cell line CHO-K1 (RCB0285, RIKEN BRC) was introduced with pcDNA3.1-hGPRC5A using Lipofectamine LTX Reagent (15338100, Themo Fisher Scientific) in Ham's F-12K medium containing 10% FBS, and incubated at 37°C and 5% CO2. ２The cells were cultured overnight under the following conditions: in Ham's F-12K medium containing 10% FBS with the selection marker zeocin (final concentration 600 μg / mL) at 37°C and 5% CO2. ２ Under these conditions, a CHO-K1 cell line (hereinafter referred to as "CHO-K1-hGPRC5A cells") that stably expresses human GPRC5A protein was obtained by culturing the aforementioned cells. pcDNA3.1-hGPRC5A was introduced into human kidney epithelial cell line 293T (RCB2202, RIKEN BRC, hereinafter referred to as "293T cell line") using Lipofectamine LTX Reagent in 10% FBS-containing DMEM medium, and cultured at 37°C and 5% CO2. ２ The cells were cultured overnight in the presence of [unspecified substance]. They were cultured in 10% FBS-containing DMEM medium containing the selection marker zeosin (final concentration 400 μg / mL) at 37°C and 5% CO2. ２ Under these conditions, the resulting transduced cells were cultured to obtain a 293T cell line (hereinafter referred to as "293T-hGPRC5A cells") that stably expresses human GPRC5A protein.

[0117] 1-2 Preparation of Hybridomas Producing Mouse Anti-GPRC5A Antibody Human GPRC5A-expressing cell lines or human GPRC5A protein were suspended in TiterMax® Gold (G-3, TiterMax) or PBS(-) to prepare an immunogen solution. Six-week-old female MRL / lpr mice or BALB / cA mice were immunized multiple times with this immunogen solution. Lymphocytes were then collected from the lymph nodes or spleens of the immunized animals according to a standard procedure and used to prepare hybridomas. Mouse lymphocytes and the mouse myeloma cell line SP2 / 0-Ag14 (RCB0209, RIKEN BRC) were fused using a super cell fusion device ECFG21 (NEPPAGINE) according to a standard procedure to obtain hybridomas. The culture supernatant of the obtained hybridomas was used to screen for hybridomas that produce anti-GPRC5A antibodies.

[0118] 1-3 Antibody Screening by Flow Cytometry The binding specificity of the anti-GPRC5A antibody contained in the hybridoma culture supernatant prepared in Example 1-2 to human GPRC5A was analyzed by flow cytometry. 293T-hGPRC5A cells and 293T cells were treated with Cellstripper (25-056-CI, Corning) and sterilized in 5 × 10⁻¹⁶ PBS containing 0.5% BSA and 0.05% sodium azide (hereinafter referred to as "FACS buffer"). ６ The cells were prepared to a concentration of cells / mL. 40 μL / tube of 293T-hGPRC5A cell suspension and 293T cell suspension were added to 1.2 mL tubes, and then 40 μL of hybridoma culture supernatant was added to each cell suspension and mixed. The mixture was then allowed to stand at 4°C for 1 hour. After washing the cells twice with FACS buffer, 40 μL of Goat anti-mouse IgG antibody-Alexa 647 (A21236, Thermo Fisher Scientific) diluted to 2 μg / mL in FACS buffer was added and the cells were suspended. The mixture was then allowed to stand at 4°C for 30 minutes. After washing the cells twice with FACS buffer, they were resuspended in FACS buffer and flow cytometry analysis was performed using NovoCyte (Agilent Technologies). The average fluorescence intensity (MFI) of Alexa Fluor 647 in the cell fraction was calculated, and hybridomas that produced hybridoma culture supernatant in which the MFI of 293T-hGPRC5A cells was shifted to the higher intensity side compared to the fluorescence intensity of control 293T cells were designated as mouse anti-GPRC5A antibody-producing hybridomas (hereinafter referred to as "mouse anti-GPRC5A antibody-producing hybridomas").

[0119] 1-4 Preparation of mouse anti-GPRC5A monoclonal antibody Mouse anti-GPRC5A antibody-producing hybridomas obtained in Examples 1-3 were cultured in RPMI1640 medium containing 10% FBS and 1x HAT supplement, and then cultured in Hybridoma-SFM medium (12045084, Thermo Fisher Scientific) containing 10 ng / mL recombinant human IL-6 (200-06-20UG, Peprotech). Mouse anti-GPRC5A antibody (hereinafter referred to as "mouse anti-GPRC5A antibody") was purified from the culture supernatant using a MabSelect SuRe™ (11003493, Cytiva) column according to a conventional method.

[0120] (Example 2) In vitro evaluation of mouse anti-GPRC5A antibody 2-1 Evaluation of mouse anti-GPRC5A antibody binding by flow cytometry 293T-hGPRC5A cells and 293T cells were treated with Cellstripper and 5 × 10⁻¹⁶ FACS buffer. ６Cells were prepared at a concentration of cells / mL. Anti-GPRC5A antibody was prepared in FACS buffer to a concentration of 0.006 μg / mL to 20 μg / mL. 40 μL of this antibody was added to a 1.2 mL tube containing 40 μL / tube of cell suspension and mixed. The mixture was allowed to stand at 4°C for 1 hour. After washing the cells twice with FACS buffer, 40 μL of Goat anti-mouse IgG antibody-Alexa 647, diluted to 2 μg / mL in FACS buffer, was added and the cells were suspended. The mixture was allowed to stand at 4°C for 30 minutes. After washing the cells twice with FACS buffer, they were resuspended in FACS buffer, and flow cytometry analysis was performed using NovoCyte to calculate the MFI of Alexa Fluor 647 in the cell fraction. Mouse anti-GPRC5A antibody (MAB5239, R&D Systems) was used as a reference. As a result, it was shown that the mouse anti-GPRC5A antibodies 1B1, 26C11, 34G2, 43B7, 43D11, 47G10-2, 48B4, and 52D6 specifically bind to 293T cells expressing human GPRC5A (Figure 1). Furthermore, similar results were obtained in flow cytometry analysis using CHO-K1-hGPRC5A cells and CHO-K1 cells (Figure 2). In addition, flow cytometry analysis using human pancreatic cancer cell lines KP-3 (JCRB cell bank), human pancreatic cancer cell lines MIA PaCa-2 (JCRB cell bank), and Panc-1 (RCB2095, RIKEN BRC), which express GPRC5A, showed that the antibodies also have binding activity to cells that endogenously express GPRC5A (Figure 3). In the above study, the mouse anti-GPRC5A antibodies 1B1, 26C11, 34G2, 43B7, 43D11, 47G10-2, 48B4, and 52D6 showed a larger B value than the reference antibody. ｍａｘ The values ​​were shown. B for each cell ｍａｘ and EC ５０ This is shown in Table 1. Note that B ｍａｘ This refers to the maximum amount of antibody bound to a cell; a larger value means a greater number of antibody molecules are bound to the cell. ５０ This refers to the concentration at which antibody binding reaches 50% of the maximum reaction, and was calculated using GraphPad Prism10 (GraphPad Software).

[0121] 2-2 Evaluation of mouse anti-GPRC5A antibody uptake by internalization assay Anti-mouse IgG antibody (115-005-008, Jackson Immuno Research Laboratories) was prepared to 1 mg / mL using 0.1 M sodium bicarbonate buffer at pH 8.3. pH 8.3 pH 8.3 pH 8.3 pH 8.3 pH 8.3 pH 8.3 pH 8.3 pH 8.3 pH 8.3 pH 8.3 pH 8.3 pH 8.3 pH 8.3 pH 8.3 pH 8.3 pH 8.3 pH 8.3 pH 8.4 After the reaction was complete, 10 μL of 1 M Tris-HCl (pH 8) was added to the reaction mixture to stop the reaction and obtain a pHo-added anti-mouse IgG antibody (hereinafter referred to as "pHo-added anti-mouse IgG antibody"). The uptake of the anti-GPRC5A antibody in cells expressing human GPRC5A was evaluated by an internalization assay using the pHo-added anti-mouse IgG antibody. Specifically, 293T-hGPRC5A cells and 293T cells were incubated in 10% FBS-containing DMEM medium at a rate of 1.2 × 10⁶ ６ Prepare the cells / mL concentration, seed in 50 μL / well 96-well plates, and store at 37°C in 5% CO2. ２ The cells were cultured overnight under the following conditions. The next day, 25 μL of anti-GPRC5A antibody, adjusted to a concentration of 0.006 μg / mL to 20 μg / mL, and 25 μL of pHo-added anti-mouse IgG antibody, adjusted to a concentration of 8 μg / mL, were mixed in 10% FBS-containing DMEM medium and reacted on ice for 30 minutes. After the reaction was complete, 50 μL of the reaction solution was added to 293T-hGPRC5A cells and incubated at 37°C in 5% CO2. ２ ​Cells were cultured for 24 hours under the specified conditions. After washing the cells in well with PBS three times, PBS was added to a volume of 100 μL / well, and the fluorescence intensity at an excitation wavelength of 550 nm and an emission wavelength of 590 nm was measured using SpectraMax iD3 (Molecular Devices). As a result, it was shown that the mouse anti-GPRC5A antibodies 1B1, 26C11, 34G2, 43B7, 43D11, 47G10-2, 48B4, and 52D6 were specifically taken up by 293T cells expressing human GPRC5A (Figure 4). Furthermore, in this study, no uptake into cells was observed for the mouse IgG2a and mouse IgG2b antibodies used as references. EC in 293T-hGPRC5A cells ５０ This is shown in Table 2.

[0122] (Example 3) Determination of sequence information of the variable region of mouse anti-GPRC5A antibody 3-1 Determination of the nucleotide sequences encoding the heavy chain and light chain variable regions of mouse anti-GPRC5A antibodies The nucleotide sequences of the heavy chain and light chain variable regions of the mouse anti-GPRC5A antibodies 1B1, 26C11, 34G2, 43B7, 43D11, 47G10-2, 48B4, and 52D6 were determined. Using hybridomas that produce each antibody, the genes encoding the heavy chain and light chain variable regions of the mouse anti-GPRC5A antibodies were cloned according to a standard method using SMARTer RACE 5' / 3' Kit (634858, Takara Bio Inc.), and the nucleotide sequences and amino acid sequences of the heavy chain and light chain variable regions of each antibody were determined. Table 3 shows the sequence numbers indicating the amino acid sequences of the heavy chain and light chain variable regions of each mouse anti-GPRC5A antibody.

[0123] ​​(Example 4) Production of human chimeric anti-GPRC5A antibodies Based on the nucleotide sequences of the heavy chain variable region and light chain variable region of the mouse anti-GPRC5A antibodies 1B1, 26C11, 34G2, 43B7, 43D11, 47G10-2, 48B4, and 52D6 determined in Example 3-1, human chimeric antibodies were produced. The obtained human chimeric antibody clones are collectively referred to as "human chimeric anti-GPRC5A antibodies," and each clone is referred to as h1B1, h26C11, h34G2, h43B7, h43D11, h47G10-2, h48B4, and h52D6.

[0124] 4-1 Design of Amino Acid Sequences and Production of Expression Vectors for Human Chimeric Anti-GPRC5A Antibodies In producing human chimeric anti-GPRC5A antibodies, LALA mutations (L234A and L235A) were introduced into the heavy chain, in which amino acids 234 and 235 in the EU index were substituted from leucine (L) to alanine (A), respectively. Furthermore, to prevent chemical changes in the antibody, some amino acids in the heavy chain variable region or light chain variable region were substituted. The sequence numbers showing the designed amino acid sequences are shown in Table 4. In the table, G54A indicates that glycine (G) at amino acid number 54 is replaced with alanine (A), G54L indicates that glycine (G) at amino acid number 54 is replaced with leucine (L), G56A indicates that glycine (G) at amino acid number 56 is replaced with alanine (A), D99A indicates that aspartic acid (D) at amino acid number 99 is replaced with alanine (A), and G34A indicates that glycine (G) at amino acid number 34 is replaced with alanine (A). In the production of human chimeric anti-GPRC5A antibodies, pFUSEss-CHIg-hG1-LALA (hereinafter referred to as "pFUSEss-CHIg-hG1-LALA"), which is pFUSEss-CHIg-hG1 (InvivoGen) with the LALA mutation introduced, or pcDNA3.4-CHIg-hG1-LALA (hereinafter referred to as "pcDNA3.4-CHIg-hG1-LALA"), which has a human IgG1 constant region with a signal sequence and LALA mutation introduced into pcDNA3.4-TOPO (InvivoGen), were used as heavy chain expression vectors for human chimeric antibodies and humanized antibody heavy chain expression vectors. Furthermore, human chimeric antibodies and humanized antibody light chain expression vectors, pcDNA3.4-CLIG-hk (hereinafter referred to as "pcDNA3.4-CLIG-hk"), which have a signal sequence and a human κ chain constant region in pFUSE2ss-CLIG-hk (InvivoGen) or pcDNA3.4-TOPO (InvivoGen), were used as light chain expression vectors. The genes encoding the heavy chain variable region and light chain variable region of the mouse anti-GPRC5A antibody shown in Table 3 were cloned into heavy chain expression vectors and light chain expression vectors according to conventional methods. The constructed vectors are shown in Table 5.

[0125] 4-2 Preparation of Human Chimeric Anti-GPRC5A Antibody Human chimeric anti-GPRC5A antibody was prepared using the human chimeric anti-GPRC5A antibody heavy chain expression vector and human chimeric anti-GPRC5A antibody light chain expression vector described in Table 5, by the following method: ExpiFectamine CHO Transfer Kit (A29129, Thermo Fisher Scientific) and ExpiCHO-S cells (1.5 × 10⁻¹⁰ ８ (10 cells), or ExpiFectamine 293 Transfer Kit (A14524, Thermo Fisher Scientific) and Expi293F cells (7.5 × 10⁻¹). ７ ​Using [specific method], 10 μg of heavy chain expression vector and 15 μg of light chain expression vector were introduced into cells, and a culture supernatant containing anti-GPRC5A antibody was prepared. Human chimeric anti-GPRC5A antibody was purified from the culture supernatant according to a standard procedure.

[0126] (Example 5) Evaluation of binding activity of human chimeric anti-GPRC5A antibody by flow cytometry 5-1 Evaluation of binding activity of human chimeric anti-GPRC5A antibody to GPRC5A-expressing cells Using the human chimeric anti-GPRC5A antibody prepared in Example 4-2 and Goat anti-human IgG antibody-Alexa 647 (A21445, Thermo Fisher Scientific), flow cytometry analysis was performed in the same manner as in Example 2-1, and the MFI of Alexa Fluor 647 in the cell fraction was calculated. As a result, the human chimeric anti-GPRC5A antibody showed binding activity to cells expressing human GPRC5A protein (Figures 5 and 6). ｍａｘ and EC ５０ The values ​​are shown in Tables 6 and 7.

[0127] 5-2 Evaluation of binding affinity of human chimeric anti-GPRC5A antibody to GPRC5D-expressing cells A cDNA encoding the human GPRC5D protein, consisting of the amino acid sequence shown in Sequence ID No. 38, was inserted into a pcDNA3.1(+) vector to create a human GPRC5D expression vector, pcDNA3.1-hGPRC5D (hereinafter referred to as "pcDNA3.1-hGPRC5D"). 293T cell lines were cultured in DMEM medium containing 10% FBS, and pcDNA3.1-hGPRC5D was introduced using Lipofectamine LTX Reagent. 37°C, 5% CO2 ２ ​​293T cells transiently expressing human GPRC5D protein (hereinafter referred to as "293T-hGPRC5D cells") were cultured overnight under the specified conditions. Cells into which pcDNA3.1 was introduced (hereinafter referred to as "293T-vect cells") were prepared in the same manner and used as control cells. Flow cytometry analysis was performed using the human chimeric anti-GPRC5A antibody and Goat anti-human IgG antibody-Alexa 647 prepared in Example 4-2 in the same manner as in Example 2-1, and the MFI of Alexa Fluor 647 in the cell fraction was calculated. As a result, R&D Systems' mouse anti-GPRC5D antibody (MAB6300R) showed significant binding activity to cells expressing human GPRC5D protein, while the human chimeric anti-GPRC5A antibody did not show significant binding activity to cells expressing human GPRC5D protein (Figure 7). ｍａｘ The values ​​are shown in Table 8.

[0128] (Example 6) Preparation of humanized anti-GPRC5A antibodies Based on the nucleotide sequences of the heavy chain variable region and light chain variable region of the mouse anti-GPRC5A antibodies 1B1, 48B4, and 52D6 determined in Example 3-1, humanized antibodies were prepared. The obtained humanized antibody clones were collectively referred to as "humanized anti-GPRC5A antibodies," and each clone was designated as Hu1B1, Hu48B4-1, Hu48B4-2, Hu48B4-3, and Hu52D6.

[0129] ​6-1 Design of Amino Acid Sequences and Expression Vectors for Humanized Anti-GPRC5A Antibodies The design of the humanized VH and humanized VL amino acid sequences was carried out according to the method described by Tsurushita et al. (Methods 36:69-83, 2005). Specifically, the following method was used. First, three-dimensional molecular models of the variable regions were constructed for each of h1B1, h48B4, and h52D6. Using the constructed molecular models, framework amino acid residues important for the proper formation of the CDR structure or important for antigen binding were predicted. In parallel, amino acid sequences of human heavy chain variable regions or human light chain variable regions that have high homology to the amino acid sequences of the heavy chain variable regions or human light chain variable regions of each of h1B1, h48B4, and h52D6 were selected and used as acceptor sequences. Next, the CDR sequences of the acceptor sequences were replaced with the corresponding mouse CDR sequences h1B1, h48B4, and h52D6, respectively. Furthermore, framework amino acid residues derived from important mouse sequences predicted from molecular models were introduced into the acceptor sequences to create humanized antibodies. Table 9 shows the sequence numbers indicating the amino acid sequences of the heavy chain variable region and light chain variable region of each humanized antibody.

[0130] In the preparation of the humanized anti-GPRC5A antibody, pcDNA3.4-CHIg-hG1-LALA was used as the heavy chain expression vector, and pcDNA3.4-CLIG-hk was used as the light chain expression vector. The genes encoding the heavy chain variable region and light chain variable region of the humanized anti-GPRC5A antibody shown in Table 9 were cloned into the heavy chain expression vector and light chain expression vector according to standard procedures. The prepared vectors are shown in Table 10.

[0131] 6-2 Preparation of Humanized Anti-GPRC5A Antibody Humanized anti-GPRC5A antibody was prepared using the humanized anti-GPRC5A antibody heavy chain expression vector and humanized anti-GPRC5A antibody light chain expression vector described in Table 10 by the following method: ExpiFectamine CHO Transfer Kit (A29129, Thermo Fisher Scientific) and ExpiCHO-S cells (1.5 × 10⁻¹⁰ ８ ​(10 cells), or ExpiFectamine 293 Transfer Kit (A14524, Thermo Fisher Scientific) and Expi293F cells (7.5 × 10⁻¹). ７ Using [specific method], 12 μg of heavy chain expression vector and 12 μg of light chain expression vector were introduced into cells, and a culture supernatant containing anti-GPRC5A antibody was prepared. Humanized anti-GPRC5A antibody was purified from the culture supernatant according to a standard procedure.

[0132] (Example 7) Evaluation of binding affinity of humanized anti-GPRC5A antibody by flow cytometry 7-1 Evaluation of binding affinity of humanized anti-GPRC5A antibody to GPRC5A-expressing cells Using the humanized anti-GPRC5A antibody prepared in Example 6-2 and the human chimeric anti-GPRC5A antibody prepared in Example 4-2, flow cytometry analysis was performed in the same manner as in Example 2-1, and the MFI of Alexa Fluor 647 in the cell fraction was calculated. As a result, the humanized anti-GPRC5A antibody showed binding activity to cells expressing human GPRC5A protein equivalent to that of the human chimeric anti-GPRC5A antibody. EC in each cell ５０ The values ​​are shown in Tables 11 and 12.

[0133] ​​(Example 8) Preparation of human chimeric anti-GPRC5A antibody-drug conjugates and humanized anti-GPRC5A antibody-drug conjugates A human chimeric anti-GPRC5A antibody-drug conjugate was prepared by adding monomethyl auristatin E (MMAE) to the human chimeric anti-GPRC5A antibody prepared in Example 4-2. In addition, humanized anti-GPRC5A antibody-drug conjugates were prepared by adding MMAE, monomethyl auristatin F (MMAF), and exatecan derivative DXd to Hu48B4-1, one of the humanized anti-GPRC5A antibodies prepared in Example 6-2. In the preparation of the human chimeric anti-GPRC5A antibody-drug conjugate, tris(2-carboxyethyl)phosphine (TCEP) was used as a reducing agent, and the human chimeric anti-GPRC5A antibodies h26C11, h48B4, and h52D6 were reacted with VcMMAE (HY-15575, MedChemExpress) to obtain the human chimeric anti-GPRC5A antibody-drug conjugate. Furthermore, in the preparation of the humanized anti-GPRC5A antibody-drug conjugate, TCEP was used as a reducing agent, and the humanized anti-GPRC5A antibody Hu48B4-1 was reacted with VcMMAE (HY-15575, MedChemExpress), Mc-MMAF (HY-15578, MedChemExpress), or MC-GGFG-DXd (HY-13631E, MedChemExpress) to obtain the humanized anti-GPRC5A antibody-drug conjugate. The prepared human chimeric anti-GPRC5A antibody-drug conjugates are collectively referred to as "human chimeric anti-GPRC5A antibody-drug conjugates," and are named "h1B1-MMAE," "h26C11-MMAE," "h34G2L-MMAE," "h43B7-MMAE," "h43D11-MMAE," "h48B4-MMAE," and "h52D6-MMAE." The prepared humanized anti-GPRC5A antibody-drug conjugates are collectively referred to as "humanized anti-GPRC5A antibody-drug conjugates," and are named "Hu48B4-1-MMAE," "Hu48B4-1-MMAF," and "Hu48B4-1-GGFG-DXd." The drug-antibody ratio was calculated by LC-MS. Table 13 shows the drug-antibody ratio (DAR) of the prepared antibody-drug conjugates.

[0134] ​(Example 9) In vitro evaluation of human chimeric anti-GPRC5A antibody-drug conjugates and humanized anti-GPRC5A antibody-drug conjugates Using the human chimeric anti-GPRC5A antibody-drug conjugates h1B1-MMAE, h26C11-MMAE, h34G2L-MMAE, h43B7-MMAE, h43D11-MMAE, h48B4-MMAE, h52D6-MMAE prepared in Example 8 and the humanized anti-GPRC5A antibody-drug conjugates Hu48B4-1-MMAE, Hu48B4-1-MMAF, Hu48B4-1-GGFG-DXd, the binding property and cytotoxic activity against GPRC5A were evaluated.

[0135] 9-1 Evaluation of binding property of human chimeric anti-GPRC5A antibody-drug conjugates and humanized anti-GPRC5A antibody-drug conjugates by flow cytometry Using the human chimeric anti-GPRC5A antibody prepared in Example 4-2, the human chimeric anti-GPRC5A antibody-drug conjugates and humanized anti-GPRC5A antibody-drug conjugates prepared in Example 8, flow cytometry analysis was performed using Cytoflex (Beckman Coulter) or NovoCyte in the same manner as in Example 2-1, and the MFI of Alexa Fluor 647 in the cell fraction was calculated. The human chimeric anti-GPRC5A antibody-drug conjugate showed a binding activity comparable to that of the human chimeric anti-GPRC5A antibody against cells expressing human GPRC5A (Figure 8). Also, the humanized anti-GPRC5A antibody-drug conjugate showed a binding activity comparable to that of the humanized anti-GPRC5A antibody. The B ｍａｘ and EC ５０ values of the human chimeric anti-GPRC5A antibody-drug conjugate and human chimeric antibody are shown in Tables 14 and 15, and the B ｍａｘ and EC ５０ values of the humanized anti-GPRC5A antibody-drug conjugate and human chimeric antibody are shown in Table 16.

[0136] 9-2 Evaluation of Cytotoxicity Using Human Chimeric Anti-GPRC5A Antibody-Drug Conjugates and Humanized Anti-GPRC5A Antibody-Drug Conjugates For the evaluation of cytotoxicity using human chimeric anti-GPRC5A antibody-drug conjugates, MIA PaCa-2 cell suspension prepared at a concentration of 6250 cells / mL in MEM medium containing 10% FBS, or Panc-1 cell suspension prepared at a concentration of 31250 cells / mL in RPMI medium containing 10% FBS, was seeded at 80 μL / well in a black clear-bottom 96-well plate (3904, Corning), and the cells were incubated at 37°C under 5% CO2. ２ The cells were incubated overnight under the following conditions. In addition, 80 μL / well of MEM medium containing 10% FBS was added to the blank wells. The following day, 20 μL / well of human chimeric anti-GPRC5A antibody-drug conjugate, prepared to a final concentration of 0.002 μg / mL to 10 μg / mL in MEM medium containing 10% FBS, was added, and the cells were incubated at 37°C and 5% CO2. ２ Cells were cultured for 144 hours under the specified conditions. Additionally, 20 μL / well of MEM medium containing 10% FBS was added to the Blank and Vehicle wells. After culturing, 100 μL / well of CellTiter-Glo (G9242, Promega) was added to the cells, and the luminescence was measured using Ensight (PerkinElmer). Cell viability was calculated using the following formula: Cell viability (%) = (A - B) / (C - B) × 100 A: Luminescence in the sample well B: Luminescence in the Blank well C: Luminescence in the Vehicle well IC ５０It refers to the concentration at which cell proliferation is inhibited by 50% by the antibody-drug conjugate, and was calculated using GraphPad Prism 10 (GraphPad Software). Similarly, in the cytotoxicity evaluation by the humanized anti-GPRC5A antibody-drug conjugate, a 293T-hGPRC5A cell suspension prepared at a concentration of 5550 cells / mL, a 293T cell suspension prepared at a concentration of 2780 cells / mL, or a KP-3 cell suspension prepared at a concentration of 11100 cells / mL in DMEM medium containing 10% FBS was seeded into a white clear-bottom 96-well plate (165306, Thermo Fisher Scientific) at 90 μL / well, and a humanized anti-GPRC5A antibody-drug conjugate prepared to a final concentration of 0.005 μg / mL to 30 μg / mL was added at 10 μL / well. As a result, h26C11-MMAE, h48B4-MMAE, and h52D6-MMAE were shown to have cytotoxic activity against MIA PaCa-2 cells and Panc-1 cells (Figure 9). Furthermore, Hu48B4-1-MMAE showed cytotoxic activity specific to human GPRC5A protein-expressing cells against 293T-hGPRC5A cells expressing GPRC5A, and also showed cytotoxicity against KP-3 cells expressing GPRC5A protein (Figure 10). The IC ５０ values of the human chimeric anti-GPRC5A antibody-drug conjugate are shown in Tables 17 and 18, and the IC ５０ values of the humanized anti-GPRC5A antibody-drug conjugate are shown in Table 19. Similar to Hu48B4-1-MMAE, it was confirmed that Hu48B4-1-MMAF and Hu48B4-1-GGFG-DXd also have cytotoxic activity against cells expressing GPRC5A.

[0137] 9-3 Evaluation of Cytotoxicity of Spheroids Using Anti-GPRC5A Antibody-Drug Conjugates MIA PaCa-2 cells were prepared in MEM medium containing 10% FBS at a concentration of 15,000 cells / mL. The prepared cell suspension was seeded at 80 μL / well in a round-bottom ultra-low adhesion surface 96-well plate (Corning). Human chimeric anti-GPRC5A antibody was added as in Example 9-2, and cell viability was measured. CellTiter-Glo3D (G9683, Promega) was used for measurement. Panc-1 cells were prepared in RPMI medium containing 10% FBS at a concentration of 11,250 cells / mL using the same method, and cell viability was measured. h26C11-MMAE, h48B4-MMAE, and h52D6-MMAE were shown to have cytotoxic activity against spheroids of MIA PaCa-2 cells or Panc-1 cells (Figure 9). ５０ The values ​​are shown in Table 20.

[0138] (Example 10) In vivo evaluation of human chimeric anti-GPRC5A antibody-drug conjugate The in vivo antitumor activity of h48B4-1-MMAE, a human chimeric anti-GPRC5A antibody-drug conjugate prepared in Example 8, was evaluated using a subcutaneous xenograft model. Specifically, 5 × 10⁶ MIA PaCa-2 cells were used. ６ The tumors were subcutaneously transplanted into the right flank of 6-8 week old female BALB / c nude mice. The longest and shortest diameters of the transplanted tumors were measured with digital calipers, and the tumor volume was calculated using the following formula: Tumor volume (mm²) ３ ) = 0.5 × major axis (mm) × [minor axis (mm)] ２ The average tumor volume in mice is 150 mm². ３When tumor volume reached a certain level, patients were divided into groups based on tumor volume (Day 1), and the human chimeric anti-GPRC5A antibody-drug conjugate h48B4-MMAE was administered intravenously at a dose of 5 mg / kg. Similarly, the isotype control group received human IgG1-MMAE at a dose of 5 mg / kg, and the control group (vehicle group) received PBS, a dilution solvent for various antibody-drug conjugates, intravenously. Administration was performed on the day of group division, and tumor volume was measured twice a week. As a result, an antitumor effect was confirmed in the group administered with the human chimeric anti-GPRC5A antibody-drug conjugate (Figure 11).

[0139] The anti-GPRC5A antibody or its antigen-binding fragment of the present invention can be used in various conjugates for the treatment of cancer.

Claims

1. An anti-GPRC5A antibody or its antigen-binding fragment comprising a heavy chain variable region and a light chain variable region as described in any of (a) to (n) below: (a) A heavy chain variable region comprising CDR1 consisting of the amino acid sequence of amino acids 31 to 35 of SEQ ID NO: 3, CDR2 consisting of the amino acid sequence of amino acids 50 to 66 of SEQ ID NO: 3, and CDR3 consisting of the amino acid sequence of amino acids 99 to 106 of SEQ ID NO: 3, and a light chain variable region comprising CDR1 consisting of the amino acid sequence of amino acids 24 to 34 of SEQ ID NO: 4, CDR2 consisting of the amino acid sequence of amino acids 50 to 56 of SEQ ID NO: 4, and CDR3 consisting of the amino acid sequence of amino acids 89 to 97 of SEQ ID NO: 4; (b) A heavy chain variable region including CDR1 consisting of the amino acid sequence of amino acids 31 to 35 of SEQ ID NO: 5, CDR2 consisting of the amino acid sequence of amino acids 50 to 66 of SEQ ID NO: 5, and CDR3 consisting of the amino acid sequence of amino acids 99 to 113 of SEQ ID NO: 5, and a light chain variable region including CDR1 consisting of the amino acid sequence of amino acids 24 to 34 of SEQ ID NO: 6, CDR2 consisting of the amino acid sequence of amino acids 50 to 56 of SEQ ID NO: 6, and CDR3 consisting of the amino acid sequence of amino acids 89 to 97 of SEQ ID NO: 6; (c) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 7, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 7, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 108 of SEQ ID NO: 7; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 8, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 8, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 8;(d) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 9, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 9, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 108 of SEQ ID NO: 9, and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 10, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 10, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 10; (e) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 11, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 11, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 109 of SEQ ID NO: 11; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 34 of SEQ ID NO: 12, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 56 of SEQ ID NO: 12, and CDR3 consisting of amino acid sequences from amino acid numbers 89 to 97 of SEQ ID NO: 12; (f) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 13, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 13, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 112 of SEQ ID NO: 13; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 14, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 14, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 14;(g) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 15, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 15, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 108 of SEQ ID NO: 15; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 39 of SEQ ID NO: 16, CDR2 consisting of amino acid sequences from amino acid numbers 55 to 61 of SEQ ID NO: 16, and CDR3 consisting of amino acid sequences from amino acid numbers 94 to 102 of SEQ ID NO: 16; (h) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 17, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 17, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 17; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 18, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 18, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 18; and (i) A heavy chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 31 to 35 of SEQ ID NO: 19, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 66 of SEQ ID NO: 19, and CDR3 consisting of amino acid sequences from amino acid numbers 99 to 109 of SEQ ID NO: 19; and a light chain variable region including CDR1 consisting of amino acid sequences from amino acid numbers 24 to 34 of SEQ ID NO: 20, CDR2 consisting of amino acid sequences from amino acid numbers 50 to 56 of SEQ ID NO: 20, and CDR3 consisting of amino acid sequences from amino acid numbers 89 to 97 of SEQ ID NO: 20;and (j) a heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 39, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 39, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 39, and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 40, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 40, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 40; and (k) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 41, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 41, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 41; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 42, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 42, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 42; and (l) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 43, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 43, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 43; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 44, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 44, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 44;and (m) a heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 45, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 45, and CDR3 consisting of amino acid sequences 99 to 106 of SEQ ID NO: 45, and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 46, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 46, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO: 46; and (n) A heavy chain variable region including CDR1 consisting of amino acid sequences 31 to 35 of SEQ ID NO: 47, CDR2 consisting of amino acid sequences 50 to 66 of SEQ ID NO: 47, and CDR3 consisting of amino acid sequences 99 to 109 of SEQ ID NO: 47; and a light chain variable region including CDR1 consisting of amino acid sequences 24 to 34 of SEQ ID NO: 48, CDR2 consisting of amino acid sequences 50 to 56 of SEQ ID NO: 48, and CDR3 consisting of amino acid sequences 89 to 97 of SEQ ID NO:

48.

2. An anti-GPRC5A antibody or antigen-binding fragment thereof according to claim 1, comprising a heavy chain variable region and a light chain variable region as described in any of (a) to (n) below: (a) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 3, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 4; (b) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 5, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 6; (c) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 7, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 8; (d) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 9, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 10; (e) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 11, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 12; (f) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 13, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 14; (g) a heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 15, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 16; (h) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 17, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 18; and (i) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 19, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 20; and (j) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 39, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 40; and (k) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 41, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 42; and (l) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 43, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 44; and (m) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 45, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO: 46; and (n) A heavy chain variable region consisting of the amino acid sequence of SEQ ID NO: 47, and a light chain variable region consisting of the amino acid sequence of SEQ ID NO:

48.

3. The anti-GPRC5A antibody according to claim 2, which is an IgG antibody.

4. An anti-GPRC5A antibody or antigen-binding fragment thereof according to any one of claims 1 to 3, wherein any amino acid residue is substituted with cysteine ​​or a non-natural amino acid.

5. Post-translation modified anti-GPRC5A antibody or antigen-binding fragment thereof according to any one of claims 1 to 4.

6. The anti-GPRC5A antibody or antigen-binding fragment thereof according to claim 5, wherein the post-translational modification is the addition of an N-linked or O-linked glycan, processing of the N-terminus or C-terminus, deamidation, isomerization of aspartic acid, and / or oxidation of methionine.

7. A complex comprising an anti-GPRC5A antibody or its antigen-binding fragment according to any one of claims 1 to 6.

8. The complex according to claim 7, wherein the complex is an antibody-drug conjugate, a radioisotope-labeled antibody, or a multispecific antibody.

9. An anti-GPRC5A antibody or an antigen-binding fragment thereof according to any one of claims 1 to 6, to which a drug is bound via a linker, represented by the following formula (I): Ab-(L １ -D １ n １１ -D ２ n １２ -…-D ｐ n １Ｎ ).sub.m １ -(L ２ -D １ n ２１ -D ２ n ２２ -…-D ｐ n ２Ｎ ).sub.m ２ -…-(L Ｋ -D １ n Ｋ１ -D ２ n Ｋ２ -…-D ｐ n ＫＮ ).sub.m ｋ (I) In formula (I), Ab is an anti-GPRC5A antibody or an antigen-binding fragment thereof, D １ to D ｐ are drugs, L １ to L Ｋ are linkers, n １１ to n ＫＮ , m １ to m ｋ are each an arbitrary integer of 0 or more, an anti-GPRC5A antibody-drug conjugate.

10. The anti-GPRC5A antibody-drug conjugate according to claim 9, wherein the drug is a cytotoxic agent.

11. The anti-GPRC5A antibody-drug conjugate according to claim 10, wherein the cytotoxic agent is a DNA inhibitor or a microtubule polymerization inhibitor.

12. The following drugs are represented by formulas (IIa), (IIb), (IIIa), or (IIIb): (IIa) (IIb) (IIIa) (IIIb) The anti-GPRC5A antibody-drug conjugate according to claim 11, comprising MMAE, MMAF, exatecan, or an exatecan derivative DXd, wherein the wavy line in the formula represents a bond.

13. The anti-GPRC5A antibody-drug conjugate according to any one of claims 10 to 12, wherein the linker is a cleavable linker.

14. The linker is one of the following equations (IV) to (VIII): (IV) (V) (VI) (VII) The anti-GPRC5A antibody-drug conjugate according to any one of claims 7 to 13, comprising (VIII), wherein m is the number of [(linker)-(drug)] moieties covalently linked to the antibody, D is a drug, Ab is an anti-GPRC5A antibody as described herein, and S is a sulfur atom of the antibody.

15. The following formula (IV) is used as the linker: (IV) The anti-GPRC5A antibody-drug conjugate according to claim 13, comprising a Val-Cit linker, wherein m is the number of [(linker)-(drug)] moieties covalently linked to the antibody, D is a drug, Ab is an anti-GPRC5A antibody as described herein, and S is a sulfur atom of the antibody.

16. The linker-drug is one of the following formulas (IX) to (XIII): (IX) (X) (XI) (XII) The anti-GPRC5A antibody-drug conjugate according to any one of claims 7 to 14, comprising (XIII), wherein m is the number of [(linker)-(cytotoxic agent)] moieties covalently linked to the antibody, Ab is an anti-GPRC5A antibody as described herein, and S is a sulfur atom of the antibody.

17. A pharmaceutical composition comprising an anti-GPRC5A antibody or its antigen-binding fragment or complex, or an anti-GPRC5A antibody-drug conjugate, as described in any one of claims 1 to 16, and a pharmaceutically acceptable excipient.

18. An anti-GPRC5A antibody or its antigen-binding fragment, or a complex, or an anti-GPRC5A antibody-drug conjugate, according to any one of claims 1 to 16, for use in the treatment of cancer.

19. The pharmaceutical composition according to claim 17, for use in the treatment of cancer.

20. A method for treating cancer, comprising the step of administering a therapeutically effective amount of an anti-GPRC5A antibody or its antigen-binding fragment, or complex, or an anti-GPRC5A antibody-drug conjugate, as described in any one of claims 1 to 16.

21. Use of an anti-GPRC5A antibody or its antigen-binding fragment, or complex, or an anti-GPRC5A antibody-drug conjugate, according to any one of claims 1 to 16, in the manufacture of a pharmaceutical composition for the treatment of cancer.

22. A polynucleotide encoding the amino acid sequence according to any one of claims 1 to 6.

23. A vector comprising the polynucleotide described in claim 22.

24. A host cell comprising the polynucleotide described in claim 22 or the vector described in claim 23.

25. A method for producing an anti-GPRC5A antibody or an antigen-binding fragment thereof, comprising the step of culturing the host cells described in claim 24.

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