Antibody-drug conjugate containing anti-CD138 antibody

Abstract

Provided is an antibody-drug conjugate (ADC) that specifically binds to CD138 and exhibits an excellent antitumor effect.　In the ADC, monomethyl auristatin E is bound via a linker to an anti-CD138 antibody having a specific amino acid sequence.

Description

Antibody-drug conjugates containing anti-CD138 antibodies

[0001] The present invention relates to antibody-drug conjugates (ADCs) in which a drug is bound via a linker to an antibody that specifically binds to CD138, and antibodies that can be used in such antibody-drug conjugates.

[0002] Antibody-drug conjugates (ADCs), which combine a cytotoxic drug with an antibody that binds to an antigen expressed on the surface of cancer cells and can be internalized by the cells, can selectively deliver drugs to cancer cells, and are therefore expected to accumulate the drug within the cancer cells and kill the cancer cells (Non-Patent Documents 1 to 3). For example, Mylotarg (registered trademark: Gemtuzumab Ozogamicin), an anti-CD33 antibody conjugated to calicheamicin, has been approved as a therapeutic agent for acute myeloid leukemia. Furthermore, Adcetris (registered trademark: Brentuximab Vedotin), an anti-CD30 antibody conjugated to monomethyl auristatin E (MMAE), has been approved as a therapeutic agent for Hodgkin's lymphoma and anaplastic large cell lymphoma (Non-Patent Document 4). The targets of the ADCs approved to date are all known to have numerous target molecules expressed on the surface of cancer cells.

[0003] CD138 functions as a receptor for the extracellular matrix and has been reported to be expressed in multiple myeloma (MM) cells as well as in tissues of pancreatic cancer, breast cancer, prostate cancer, non-Hodgkin's lymphoma, and the like (Non-Patent Documents 5 and 6). Furthermore, the dynamics of CD138 (internalization and recycling of CD138) have recently attracted attention (Non-Patent Document 7). This property may contribute to active cellular uptake as a target for ADCs, making it suitable as an ADC target.

[0004] An ADC targeting CD138 is BT062 (indatuximab ravatansine), which is a chimeric IgG4 antibody nBT062 with the maytansine analog DM4 conjugated to its lysine residue via a SPDB linker (Patent Document 1). BT062 binds to CD138 expressed on the surface of multiple myeloma cells and exhibits high cytotoxicity and antitumor effects (Non-Patent Document 8). Although BT062 progressed to clinical trials, its efficacy was limited, and development was discontinued. Clinical trials of BT062 have also reported relatively rapid clearance from the blood, ocular toxicity thought to be due to DM4, and the development of anti-antibodies in patients' blood (Non-Patent Document 9).

[0005] Furthermore, while the risk of immunogenicity generally increases in the following order: fully human antibodies, humanized antibodies, chimeric antibodies, and xenoantibodies (such as mouse antibodies), BT062 uses a chimeric antibody as its antibody portion, which raises concerns about the risk of immunogenicity.

[0006] A chimeric IgG1 antibody obtained by class-switching nBT062 is known (Patent Document 2), but it is used as a fusion protein bound to a masked interferon and is not used as the antibody portion of an ADC.

[0007] In creating new antibody-drug conjugates that can meet clinical needs, various combinations of antibodies, linkers, and payloads must be considered. However, even slight differences in antibody sequence can cause changes in physical properties, leading to aggregation of the antibody itself, changes in the reactivity of the linker-payload, and aggregation and reduced stability of the ADC. Therefore, there is no universal linker-payload that is compatible with every antibody, and screening for each antibody sequence is required to find an appropriate combination. Therefore, it is common knowledge in the technical field that it is not easy for those skilled in the art to find an antibody-drug conjugate that is useful as a pharmaceutical. Payloads that have been approved and adopted as ADCs include MMAE, Dxd, and DM1, but no ADCs in which these are conjugated to a CD138 antibody have been known to date.

[0008] As described above, there is a recognized need for therapeutic agents for CD138-expressing cancers, which are highly expressed in various tumors. CD138 is considered a promising target for ADCs due to its cell surface expression and internalization ability. However, no ADCs that overcome the above concerns have been identified to date.

[0009] International Publication No. 2009 / 080830 International Publication No. 2020 / 214690

[0010] Bioconjugate Chem. (2010) 21, 5-13. Current Opinion in Chemical Biology (2010) 14, 529-537. Expert Opin. Biol. Ther. (2004) 4, 1445-1452. Nature Biotechnology (2012) 30, 631-637. Oncotarget (2015) 6(30):28693-28715Am J Physiol Cell Physiol. 2022 Jul 1;323(1):C29-C45. Nature (2019) 568(7752):410-414J Hematol Oncol (2017) 11:10(1):13Clin Lymphoma Myeloma Leuk. (2019) 19(6):372-380

[0011] The present invention aims to provide an antibody-drug conjugate that specifically binds to cancer cells expressing CD138 and exhibits excellent antitumor effects. Another problem to be solved by the present invention is to provide an antibody that is suitable as the antibody moiety of an antibody-drug conjugate that is useful as an antitumor agent.

[0012] The inventors of the present invention conducted extensive research and discovered a humanized antibody sequence that maintains specific binding to CD138 while converting the antibody constant region to IgG1. Furthermore, by combining various linkers and payloads, they discovered an antibody-drug conjugate that does not aggregate in solution, exhibits excellent plasma stability, and exhibits high antitumor efficacy, leading to the completion of the present invention. The ADC of the present invention is expected to be more stable in vivo and have reduced immunogenicity due to the IgG1-conversion and humanization of the antibody sequence. Furthermore, the excellent plasma stability of the ADC may reduce the risk of toxicity due to drug dissociation in the blood. Furthermore, while antibody denaturation and aggregation can lead to reduced efficacy and unexpected side effects, the ADC of the present invention is less susceptible to denaturation and aggregation even when heated, providing excellent stability as a pharmaceutical.

[0013] The present invention has the following features. [1] An antibody-drug conjugate (ADC) represented by the following general formula 1: Ab-(L-D)p (1) [wherein Ab is any one of the following antibodies that specifically bind to CD138 selected from the group consisting of (1) to (3), wherein the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16; (2) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 18 and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16; (3) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 22 and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16; L is a linker; D is monomethylauristatin; and p is 1 to 12.]

[0014] [2] The antibody-drug conjugate (ADC) according to [1] above, wherein Ab is any one selected from the group consisting of the following (1) to (3): (1) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 44, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34, and having specific binding ability to CD138. (2) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 46 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34, or an antibody comprising: a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 18 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 46, and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 34, and having specific binding ability to CD138. (3) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 48 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34, or an antibody comprising: a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 22 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 48, and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 34, and having specific binding ability to CD138.

[0015] [3] The antibody-drug conjugate (ADC) according to [1] or [2] above, wherein Ab is any one selected from the group consisting of the following (1) to (3): (1) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34. (2) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 46 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34. (3) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 48 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34.

[0016] [4] The antibody-drug conjugate (ADC) according to any one of [1] to [3] above, wherein L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB).

[0017] [5] The antibody-drug conjugate (ADC) according to any one of [1] to [4] above, wherein D is monomethyl auristatin E.

[0018] [6] The antibody-drug conjugate (ADC) according to any one of [1] to [5] above, wherein p is 1 to 8.

[0019] [7] The antibody-drug conjugate (ADC) according to any one of [1] to [6] above, wherein Ab is an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16, L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB), D is monomethylauristatin E, and p is 1 to 8.

[0020] [8] The antibody-drug conjugate (ADC) according to any one of [1] to [7] above, wherein Ab is an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB), D is monomethylauristatin E, and p is 1 to 8.

[0021] [9] A pharmaceutical composition comprising the antibody-drug conjugate (ADC) according to any one of [1] to [8] above, and a carrier.

[0022]

[10] An antitumor agent comprising the antibody-drug conjugate (ADC) according to any one of [1] to [8] above.

[0023]

[11] The antitumor agent according to

[10] above, for treating a cancer in which CD138 is expressed.

[0024]

[12] The antitumor agent according to

[10] above, which is administered in combination with other antitumor agents.

[0025]

[13] The antitumor agent according to

[10] above, for treating gastric cancer, pancreatic cancer, colon cancer, lung cancer, breast cancer or urothelial cancer.

[0026]

[14] An antibody that specifically binds to CD138, the antibody being any one selected from the group consisting of (1) to (3) below, wherein the constant region of the antibody is human IgG1: (1) An antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16. (2) An antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 18, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16. (3) An antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 22, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16.

[0027]

[15] The antibody according to

[14] above, which is any one selected from the group consisting of (1) to (3) below: (1) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 44, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34, and having the ability to specifically bind to CD138. (2) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 46 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34, or an antibody comprising: a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 18 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 46, and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 34, and having specific binding ability to CD138. (3) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 48 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34, or an antibody comprising: a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 22 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 48, and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 34, and having specific binding ability to CD138.

[0028]

[16] The antibody according to

[14] or

[15] above, which is any one selected from the group consisting of the following (1) to (3): (1) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34. (2) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 46 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34. (3) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 48 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34.

[0029]

[17] A method for treating cancer, comprising a step of administering the antibody-drug conjugate (ADC) according to any one of [1] to [8] above to a subject.

[0030]

[18] Use of the antibody-drug conjugate (ADC) according to any one of [1] to [8] above for the treatment of cancer.

[0031]

[19] The antibody-drug conjugate (ADC) according to any one of [1] to [8] above, for use in treating cancer.

[0032]

[20] Use of the antibody-drug conjugate (ADC) according to any one of [1] to [8] above for the manufacture of an antitumor agent.

[0033]

[21] A method for treating cancer, comprising the step of administering the antibody-drug conjugate (ADC) according to any one of [1] to [8] above and another antitumor agent to a subject.

[0034]

[22] Use of the antibody-drug conjugate (ADC) according to any one of [1] to [8] above for the treatment of cancer, wherein the ADC is administered in combination with other antitumor agents.

[0035]

[23] The antibody-drug conjugate (ADC) according to any one of [1] to [8] above, for use in the treatment of cancer, wherein the ADC is administered in combination with another antitumor agent.

[0036]

[24] Use of the antibody-drug conjugate (ADC) according to any one of [1] to [8] above for the manufacture of an antitumor agent to be administered in combination with another antitumor agent.

[0037]

[25] The antibody-drug conjugate (ADC) according to any one of [1] to [8] above, which has stable physical properties.

[0038]

[26] Denaturation midpoint temperature T ｍ 2 is 80°C or higher and the aggregation starting temperature T ａｇｇ The antibody-drug conjugate (ADC) according to any one of [1] to [8] above, wherein 266 is 70°C or higher.

[0039] This specification includes the disclosure of Japanese Patent Application No. 2023-032088, from which the present application claims priority.

[0040] The antibody-drug conjugates (ADCs) of the present invention exhibit excellent antitumor effects by specifically binding to cancer cells expressing CD138 due to their excellent binding ability and being internalized into the cells. Furthermore, the ADCs of the present invention exhibit excellent stability in plasma, making it unlikely that the drug will dissociate in the blood and cause toxicity.

[0041] Furthermore, the antibody of the present invention has excellent binding ability to CD138, and is useful not only as a reagent for detecting CD138, but also as the antibody portion of an ADC.

[0042] Furthermore, the antibodies and ADCs of the present invention have low aggregation properties and are useful as pharmaceuticals and raw materials thereof.

[0043] It is a diagram showing the cell-binding properties of Antibody 1 and Antibodies 3 to 9 against AsPC-1 cells. It is a diagram showing the combination of drug linkers bound to an antibody for an ADC obtained using an anti-CD138 antibody (ADCs 1 to 5). It is a diagram showing the combination of drug linkers bound to an antibody for an ADC obtained using an anti-CD138 antibody (ADCs 6 to 10, continuation of Figure 2-1). It is a diagram showing the combination of drug linkers bound to an antibody for an ADC obtained using an anti-CD138 antibody (ADCs 11 to 14, continuation of Figure 2-2). It is a diagram showing the cell-binding property of Antibody 1 against Capan-1 cells (Figure 3A) and non-binding property against Jurkat cells (Figure 3B). It is a diagram showing the antitumor effects (in vivo) of ADCs 2 and 3. Figure 4A shows the change in tumor volume over time, and Figure 4B shows the change in body weight over time. It is a diagram showing the antitumor effects (in vivo) of ADCs 3 and 12 to 14. Figure 4A shows the change in tumor volume over time, and Figure 4B shows the change in body weight over time. It is a diagram showing the sequences of SEQ ID NOs: 1 to 7. It is a diagram showing the sequences of SEQ ID NOs: 8 to 12. It is a diagram showing the sequences of SEQ ID NOs: 13 to 17. It is a diagram showing the sequences of SEQ ID NOs: 18 to 22. It is a diagram showing the sequences of SEQ ID NOs: 23 to 25. It is a diagram showing the sequences of SEQ ID NOs: 26 to 28. It is a diagram showing the sequences of SEQ ID NOs: 29 and 30. It is a diagram showing the sequences of SEQ ID NOs: 31 and 32. It is a diagram showing the sequences of SEQ ID NOs: 33 to 35. It is a diagram showing the sequences of SEQ ID NOs: 36 to 38. It is a diagram showing the sequences of SEQ ID NOs: 39 and 40. It is a diagram showing the sequences of SEQ ID NOs: 41 to 43. It is a diagram showing the sequences of SEQ ID NOs: 44 to 46. It is a diagram showing the sequences of SEQ ID NOs: 47 and 48. It is a diagram showing the sequences of SEQ ID NOs: 49 and 50.

[0044] Hereinafter, the present invention will be described in detail. The present invention provides an antibody that specifically binds to CD138 and a conjugate of the antibody and a drug having antitumor activity (ADC: Antibody-drug conjugate).

[0045] <Antibody> The present invention provides an antibody that specifically binds to CD138.

[0046] The antibody of the present invention is characterized by its high binding affinity to a specific epitope sequence (LPEV) (SEQ ID NO: 50) in CD138, and is therefore useful as a reagent for detecting, diagnosing, isolating, etc. CD138. Furthermore, due to its tumor tissue selectivity based on its binding affinity, it is useful as an antibody moiety in an antibody-drug conjugate (ADC) having antitumor activity.

[0047] Unless otherwise specified, "CD138" in the present invention refers to human CD138 protein. Human CD138 protein includes not only the protein consisting of the amino acid sequence shown in SEQ ID NO: 49, but also proteins in which one or several, for example, 1 to 10, preferably 1 to 5, more preferably 1 or 2, and even more preferably 1 amino acid has been substituted, deleted, and / or added, and which have biological activity equivalent to that of said protein.

[0048] The antibodies of the present invention include antibodies 3 to 6 and antibodies 10 to 12 described below.

[0049] As described above, antibody 2 herein is a known chimeric antibody whose constant region is human IgG4 (hereinafter also referred to as "nBT062"). Generally, attempts have been made to humanize chimeric antibodies and the like to reduce the risk of antigenicity, but this is known to result in a reduction or loss of antigen-binding ability. As described in the Examples below, antibodies 7 to 9 actually exhibited reduced CD138-binding ability compared to antibody 1. Therefore, the inventors of the present invention undertook various efforts to improve binding ability and found that antibodies 3 to 6, which incorporate certain mutations in the amino acid sequences in the antibody variable regions, exhibit improved CD138-binding ability compared to antibodies 7 to 9. Antibodies 4 and 7, antibodies 5 and 8, and antibodies 6 and 9 all share the same heavy chain, and only differ by one amino acid in the variable region of their light chains. In other words, the improved CD138-binding ability was achieved by a single amino acid difference in the variable region.

[0050] The antibody of the present invention is any one of the following antibodies selected from the group consisting of (1) to (3), which specifically binds to CD138 and whose constant region is human IgG1: (1) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 14 and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16, (2) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 18 and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16, or (3) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 22 and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16, and particularly preferably (1) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 14 and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16.

[0051] The antibodies of the present invention include not only antibodies comprising heavy and light chains consisting of the amino acid sequences shown in the above SEQ ID NOs, but also antibodies comprising variable regions consisting of the amino acid sequences shown in the above SEQ ID NOs in each of the heavy and light chains, and having a certain mutation in the amino acid sequence of a part other than the variable region (constant region) in at least one of the heavy and light chains, as long as they have the ability to be antibodies of the present invention.

[0052] The heavy chain variable region includes not only the heavy chain variable region consisting of the amino acid sequence shown in the above SEQ ID NO, but also a heavy chain variable region consisting of a protein having certain mutations in the amino acid sequence other than the CDRs and having the activity of an antibody heavy chain variable region, i.e., binding activity to CD138. The light chain variable region includes not only the light chain variable region consisting of the amino acid sequence shown in the above SEQ ID NO, but also a light chain variable region consisting of a protein having certain mutations in the amino acid sequence other than the CDRs and having the activity of an antibody light chain variable region, i.e., binding activity to CD138.

[0053] Here, a certain mutation includes a mutation in which one or several, for example, 1 to 10, preferably 1 to 5, more preferably 1 or 2, and even more preferably 1 amino acid is deleted, substituted, or added to the amino acid sequence of at least one of the heavy chain and light chain, except for the variable region.

[0054] Furthermore, the capabilities of the antibodies of the present invention include the ability to specifically bind to CD138, preferably the ability to specifically bind to human CD138, and more preferably the ability to specifically bind to the epitope sequence (LPEV) in human CD138.

[0055] The presence or absence of the ability to bind to CD138 can be measured by known methods.

[0056] Such amino acid sequences in which one or several amino acids have been deleted, substituted, or added in the amino acid sequence shown by the above SEQ ID NO: include those which have at least 85%, preferably at least 90%, more preferably at least 91%, even more preferably at least 92%, even more preferably at least 93%, even more preferably at least 94%, even more preferably at least 95%, even more preferably at least 96%, even more preferably at least 97%, even more preferably at least 98%, and particularly preferably at least 99% sequence identity with the amino acid sequence of a portion other than the variable region in the amino acid sequence shown by the above SEQ ID NO: when calculated using BLAST (Basic Local Alignment Search Tool at the National Center for Biological Information) or the like (for example, default, i.e., initial setting parameters).

[0057] Such a protein having an amino acid sequence in which one or several amino acids are deleted, substituted or added in the amino acid sequence shown in the above SEQ ID NO: is substantially identical to the protein consisting of the amino acid sequence shown in the above SEQ ID NO:.

[0058] A preferred antibody of the present invention is an antibody that specifically binds to CD138, which is any one selected from the group consisting of the following (1) to (3), and whose constant region is human IgG1: (1) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody that has the ability to specifically bind to CD138, comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 44, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34. (2) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 46 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34, or an antibody comprising: a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 18 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 46, and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 34, and having specific binding ability to CD138. (3) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 48 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34, or an antibody comprising: a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 22 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 48, and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 34, and having specific binding ability to CD138.

[0059] Particularly preferred is an antibody that specifically binds to CD138 as shown in (1) below, wherein the constant region of the antibody is human IgG1: (1) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody that comprises: a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 44, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34, and that has the ability to specifically bind to CD138.

[0060] Furthermore, a preferred antibody of the present invention is an antibody that specifically binds to CD138, which is any one selected from the group consisting of the following (1) to (6), wherein the antibody constant region is human IgG1: (1) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 32 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34. (2) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 36 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34. (3) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 40 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34. (4) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34. (5) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 46 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34. (6) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 48 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34.

[0061] More preferably, the antibody specifically binds to CD138 and is any one of the antibodies selected from the group consisting of the following (4) to (6), wherein the constant region of the antibody is human IgG1: (4) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34. (5) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 46 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34. (6) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 48 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34.

[0062] More preferably, the antibody specifically binds to CD138 and is defined as (1) or (4) below, wherein the constant region of the antibody is human IgG1: (1) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 32 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34. (4) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34. Particularly preferred is an antibody specifically binds to CD138 and is defined as (4) below, wherein the constant region of the antibody is human IgG1: (4) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34.

[0063] The sequence information of Antibody 1 to Antibody 12 in this specification is as shown in Table 1.

[0064] The form of the antibody of the present invention is not particularly limited as long as it is a molecule that has a heavy chain and a light chain containing the variable region shown in the above-mentioned SEQ ID NO: and is capable of binding to an antigen. For example, in addition to immunoglobulins, the form may also include antigen-binding fragments or derivatives thereof that have all or part of the functions of a complete antibody (Fab fragments, F(ab')2 fragments, single-chain antibody fragments (scFv), variable regions (Fv), Fab'iabodies which are monovalent fragments of the variable region of antibodies obtained by treating dF(ab')2 under reducing conditions, and bispecific antibodies).

[0065] The antibody of the present invention is a humanized antibody, and its constant region is human IgG1.

[0066] The antibody of the present invention can be produced using various known methods, and the production method is not particularly limited. Such known methods include the hybridoma method and the phage display method.

[0067] The antibodies of the present invention can be modified by known recombinant means, provided that the effects of the present invention are not impaired. For example, at least one amino acid in the antibody constant region can be substituted with a different residue. Such changes are made to reduce undesirable activities, such as complement-dependent cytotoxicity.

[0068] The antibodies of the present invention can be produced as recombinant antibodies. Specifically, DNA encoding each region of the antibody (DNA encoding the heavy chain variable region, light chain variable region, heavy chain constant region, and light chain constant region) can be inserted into an expression vector, host cells can be transformed with the expression vector, and the cells can be cultured to produce the antibody. In this case, the DNA encoding each region may be operably linked to elements such as a promoter, polyadenylation signal, or enhancer. "Operatively linked" refers to linking each element so that it functions. The DNA used to insert each region into the vector may contain a signal peptide that promotes antibody secretion from host cells. The mature protein can be obtained by removing the signal peptide after antibody production. Known plasmids, phages, and the like can be used as expression vectors. Prokaryotic cells such as Escherichia coli and Bacillus subtilis, and eukaryotic cells such as yeast and animal cells can be used as host cells. Among these, eukaryotic cells in which a sugar chain is bound to the antibody are preferred. Suitable animal cells include Chinese hamster ovary cells (CHO) and HEK293 cells. The expression vector may be introduced into host cells by electroporation, DEAE-dextran transfection, calcium phosphate precipitation, or the like, to transform the host cells. The produced antibody may be purified by known methods, such as methods using various types of chromatography. It is known that antibodies produced in cultured mammalian cells lack a lysine residue at the carboxyl terminus of the heavy chain, and the present invention also includes antibodies in which a lysine residue at the carboxyl terminus of the heavy chain is deleted.

[0069] The DNA encoding each region of the antibody of the present invention may be any DNA that can express each region of the antibody of the present invention, and examples thereof include DNA consisting of nucleotides represented by the sequence numbers listed in Table 1.

[0070] <Antibody-drug conjugates (ADCs)> The present invention provides antibody-drug conjugates (ADCs) represented by the following general formula 1: Ab-(L-D)p (1) [wherein Ab is any one of the following antibodies that specifically bind to CD138 selected from the group consisting of (1) to (3), wherein the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16; (2) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 18 and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16; (3) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 22 and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16; L is a linker; D is monomethylauristatin; and p is 1 to 12.]

[0071] The Ab in the ADC of the present invention is preferably the above-mentioned antibody.

[0072] In the ADCs of the present invention, L is a linker connecting an antibody and a drug, and its structure is not critical as long as it does not release the drug in the blood but is cleaved by a protease in cancer cells to release the drug. Examples of such linkers include cysteine-bonded dipeptide linkers, preferably 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB: MC-VC-PAB). MC-VC-PAB is known as a linker for ADCs.

[0073] D in the ADC of the present invention is monomethyl auristatin (MMA). Monomethyl auristatins include monomethyl auristatin E (MMAE), monomethyl auristatin D (MMAD), monomethyl auristatin F (MMAF), etc., with monomethyl auristatin E and monomethyl auristatin F being preferred, and monomethyl auristatin E being particularly preferred. Monomethyl auristatin is a known compound known to exhibit antitumor activity.

[0074] MC-VC-PAB-MMAE and MC-VC-PAB-MMAF can be purchased from MedChemExpress, Inc.

[0075] The ADCs of the present invention can be produced by known methods. For example, in an ADC, a drug is bound to an antibody via a linker, which is bound to the antibody via an amino group or cysteine ​​residue on the antibody. Specifically, the linker is bound to the antibody via a Michael addition reaction between a sulfhydryl group of cysteine ​​and maleimide, a disulfide bond formation reaction, or an amide bond formation by condensation of a lysine amino group with a carboxylic acid. In the above general formula 1, p represents the number of drug molecules that can be bound to one antibody molecule. This number of molecules is called the DAR (Drug Antibody Ratio). The DAR can be measured by known means such as hydrophobic chromatography (Methods Mol Biol. 2013;1045:275-83. doi: 10.1007 / 978-1-62703-541-5_17.).

[0076] In the ADC of the present invention, p is selected from 1 to 12, and is preferably 1 to 8, more preferably 2 to 8, more preferably 3 to 8, more preferably 4 to 8, more preferably 5 to 8, more preferably 6 to 8, more preferably 7 to 8, and particularly preferably 8. In another preferred embodiment, p is preferably 2 to 8, more preferably 2 to 6, more preferably 3 to 5, and particularly preferably 4.

[0077] The antibody-drug conjugate of the present invention may be an antibody-drug conjugate in which the number of drug molecules bound to one antibody molecule is the same, or may be a collection of antibody-drug conjugates in which the number of drug molecules bound to one antibody molecule is variable. In the latter case, p is the average number of drug molecules bound to one antibody molecule.

[0078] Furthermore, preferred ADCs of the present invention are those represented by general formula 1, in which Ab is any one selected from the group consisting of the following (1) to (3), an antibody that specifically binds to CD138, and the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16. (2) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 18, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16. (3) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 22, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16. L is a linker, D is monomethylauristatin, and p is 1 to 12.

[0079] Another preferred ADC is an antibody that specifically binds to CD138, wherein Ab in general formula 1 is any one selected from the group consisting of the following (1) to (3), and the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 14, and a light chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16. (2) an antibody comprising a heavy chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 18, and a light chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16. (3) an antibody comprising a heavy chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 22, and a light chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16. L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB: MC-VC-PAB), D is monomethylauristatin, and p is 1 to 12.

[0080] Another preferred ADC is an antibody that specifically binds to CD138, wherein Ab in general formula 1 is any one selected from the group consisting of the following (1) to (3), and the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 14, and a light chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16. (2) an antibody comprising a heavy chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 18, and a light chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16. (3) an antibody comprising a heavy chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 22, and a light chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16. L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB: MC-VC-PAB), D is monomethylauristatin, and p is 1 to 8.

[0081] Another suitable ADC is an antibody that specifically binds to CD138, wherein Ab in general formula 1 is any one selected from the group consisting of the following (1) to (3), and the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16. (2) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 18, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16. (3) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 22, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16. L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB:MC-VC-PAB), D is monomethyl auristatin E or monomethyl auristatin F, and p is 1 to 8.

[0082] Another preferred ADC is an antibody that specifically binds to CD138, wherein Ab in general formula 1 is any one selected from the group consisting of the following (1) to (3), and the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 14, and a light chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16. (2) an antibody comprising a heavy chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 18, and a light chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16. (3) an antibody comprising a heavy chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 22, and a light chain including a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16. L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB: MC-VC-PAB), D is monomethylauristatin E, and p is 1 to 8.

[0083] Another preferred ADC is an antibody that specifically binds to CD138, wherein Ab in general formula 1 is any one selected from the group consisting of the following (1) to (3), and the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain including a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and a light chain including a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16, L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB: MC-VC-PAB), D is monomethylauristatin E, and p is 1 to 8.

[0084] Another preferred ADC is an antibody that specifically binds to CD138, wherein Ab in general formula 1 is any one selected from the group consisting of the following (1) to (3), and the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16, L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB: MC-VC-PAB), D is monomethylauristatin E, and p is 3 to 8.

[0085] Another preferred ADC is an antibody that specifically binds to CD138, wherein Ab in general formula 1 is any one selected from the group consisting of the following (1) to (3), and the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain including a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and a light chain including a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16, L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB: MC-VC-PAB), D is monomethylauristatin E, and p is 3 to 5.

[0086] Another suitable ADC is an antibody that specifically binds to CD138, wherein Ab in general formula 1 is any one selected from the group consisting of the following (1) to (3), and the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody that has the ability to specifically bind to CD138, comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 44, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34. (2) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 46 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34, or an antibody comprising: a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 18 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 46, and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 34, and having specific binding ability to CD138. (3) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 48 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34, or an antibody comprising: a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 22 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 48, and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 34, and having specific binding ability to CD138. L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB), D is monomethyl auristatin E, and p is 1-8, ADC.

[0087] Another suitable ADC is an antibody having specific binding ability to CD138, wherein Ab in general formula 1 is an antibody that specifically binds to CD138 as shown in the following (1), and the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34, or an antibody having specific binding ability to CD138, wherein L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB), D is monomethylauristatin E, and p is 1 to 8.

[0088] Another suitable ADC is an antibody having specific binding ability to CD138, wherein Ab in general formula 1 is an antibody that specifically binds to CD138 as shown in (1) below, and the antibody constant region is human IgG1, and wherein: (1) an antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34, or an antibody having specific binding ability to CD138, wherein L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB), D is monomethylauristatin E, and p is 3 to 8.

[0089] Another suitable ADC is an antibody having specific binding ability to CD138, wherein Ab in general formula 1 is an antibody that specifically binds to CD138 as shown in the following (1), and the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody having specific binding ability to CD138, wherein L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB), D is monomethylauristatin E, and p is 3 to 5.

[0090] Another preferred ADC is an ADC in which, in general formula 1, Ab is any one of the following (1) to (3): an antibody that specifically binds to CD138, and the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34. (2) an antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 46 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34. (3) an antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 48 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34. L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB), D is monomethylauristatin E, and p is 1 to 8.

[0091] Another suitable ADC is an ADC in which, in general formula 1, Ab is an antibody that specifically binds to CD138 as shown in the following (1), and the constant region of the antibody is human IgG1, and (1) comprises a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB), D is monomethylauristatin E, and p is 1 to 8.

[0092] Another suitable ADC is an ADC in which, in general formula 1, Ab is an antibody that specifically binds to CD138 as shown in the following (1), and the constant region of the antibody is human IgG1, and (1) comprises a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB), D is monomethylauristatin E, and p is 3 to 8.

[0093] Another suitable ADC is an ADC in which, in general formula 1, Ab is an antibody that specifically binds to CD138 as shown in the following (1), and the constant region of the antibody is human IgG1, and (1) comprises a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB), D is monomethylauristatin E, and p is 3 to 5.

[0094] A preferred ADC of the present invention is an ADC represented by the following formula:

[0095] [In the formula, Ab is any one of the antibodies that specifically bind to CD138 selected from the group consisting of (1) to (3) below, wherein the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16; (2) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 18, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16; (3) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 22, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16; and p is 1 to 8.]

[0096] More preferably, the ADC is an antibody in which Ab specifically binds to CD138 as shown in the following (1), the constant region of which is human IgG1, and which comprises: (1) a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16, and p is 1 to 8.

[0097] More preferably, the ADC is an antibody in which Ab specifically binds to CD138 as shown in the following (1), the constant region of which is human IgG1, and which comprises: (1) a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16, and p is 3 to 8.

[0098] More preferably, the ADC is an antibody in which Ab specifically binds to CD138 as shown in the following (1), the constant region of which is human IgG1, and which comprises: (1) a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16, and p is 3 to 5.

[0099] More preferably, in the formula, Ab is any one of the following antibodies that specifically bind to CD138, selected from the group consisting of (1) to (3), wherein the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody having specific binding ability to CD138, comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 44, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34. (2) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 46 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34, or an antibody comprising: a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 18 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 46, and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 34, and having specific binding ability to CD138. (3) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 48 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34, or an antibody comprising: a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 22 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 48, and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 34, and having specific binding ability to CD138. p is 1 to 8, ADC.

[0100] More preferably, the ADC is an antibody having the ability to specifically bind to CD138, wherein Ab is an antibody shown in the following (1) that specifically binds to CD138, and whose constant region is human IgG1, and wherein: (1) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody having a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 44, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34.

[0101] More preferably, the ADC is an antibody having specific binding ability to CD138, wherein Ab is an antibody shown in the following (1) that specifically binds to CD138, and whose constant region is human IgG1, and wherein: (1) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody having specific binding ability to CD138, wherein the heavy chain comprises a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and has at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 44, and a light chain comprises a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and has at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34.

[0102] More preferably, the ADC is an antibody having specific binding ability to CD138, wherein Ab is an antibody shown in the following (1) that specifically binds to CD138, and whose constant region is human IgG1, and wherein: (1) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody having specific binding ability to CD138, wherein the heavy chain comprises a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and has at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 44, and a light chain comprises a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and has at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34.

[0103] More preferably, in the formula, Ab is an antibody that specifically binds to CD138, which is any one selected from the group consisting of the following (1) to (3), and whose constant region is human IgG1: (1) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34. (2) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 46 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34. (3) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 48 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34. An ADC in which p is 1 to 8.

[0104] More preferably, the ADC is an antibody in which Ab specifically binds to CD138 as shown in the following (1), the constant region of which is human IgG1, and which comprises a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, and p is 1 to 8.

[0105] More preferably, the ADC is an antibody in which Ab specifically binds to CD138 as shown in the following (1), the constant region of which is human IgG1, and which comprises a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, and p is 3 to 8.

[0106] More preferably, the ADC is an antibody in which Ab specifically binds to CD138 as shown in the following (1), the constant region of which is human IgG1, and which comprises a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, and p is 3 to 5.

[0107] A preferred ADC of the present invention is an ADC represented by the following formula:

[0108] [In the formula, Ab is any one of the antibodies that specifically bind to CD138 selected from the group consisting of (1) to (3) below, wherein the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16; (2) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 18, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16; (3) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 22, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16; and p is 1 to 8.]

[0109] More preferably, the ADC is an antibody in which Ab specifically binds to CD138 as shown in the following (1), the constant region of which is human IgG1, and which comprises: (1) a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16, and p is 1 to 8.

[0110] More preferably, the ADC is an antibody in which Ab specifically binds to CD138 as shown in the following (1), the constant region of which is human IgG1, and which comprises: (1) a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16, and p is 3 to 8.

[0111] More preferably, the ADC is an antibody in which Ab specifically binds to CD138 as shown in the following (1), the constant region of which is human IgG1, and which comprises: (1) a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16, and p is 3 to 5.

[0112] More preferably, in the formula, Ab is any one of the following antibodies that specifically bind to CD138, selected from the group consisting of (1) to (3), wherein the antibody constant region is human IgG1: (1) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody having specific binding ability to CD138, comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 44, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34. (2) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 46 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34, or an antibody comprising: a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 18 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 46, and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 34, and having specific binding ability to CD138. (3) An antibody comprising a heavy chain consisting of the amino acid sequence set forth in SEQ ID NO: 48 and a light chain consisting of the amino acid sequence set forth in SEQ ID NO: 34, or an antibody comprising: a heavy chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 22 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 48, and a light chain comprising a variable region consisting of the amino acid sequence set forth in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence set forth in SEQ ID NO: 34, and having specific binding ability to CD138. p is 1 to 8, ADC.

[0113] More preferably, the ADC is an antibody having the ability to specifically bind to CD138, wherein Ab is an antibody shown in the following (1) that specifically binds to CD138, and whose constant region is human IgG1, and wherein: (1) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody having a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 44, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34.

[0114] More preferably, the ADC is an antibody having specific binding ability to CD138, wherein Ab is an antibody shown in the following (1) that specifically binds to CD138, and whose constant region is human IgG1, and wherein: (1) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody having specific binding ability to CD138, wherein the heavy chain comprises a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and has at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 44, and a light chain comprises a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and has at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34.

[0115] More preferably, the ADC is an antibody having specific binding ability to CD138, wherein Ab is an antibody shown in the following (1) that specifically binds to CD138, and whose constant region is human IgG1, and wherein: (1) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody having specific binding ability to CD138, wherein the heavy chain comprises a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14 and has at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 44, and a light chain comprises a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and has at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34.

[0116] More preferably, in the formula, Ab is an antibody that specifically binds to CD138, which is any one selected from the group consisting of the following (1) to (3), and whose constant region is human IgG1: (1) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34. (2) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 46 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34. (3) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 48 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34. An ADC in which p is 1 to 8.

[0117] More preferably, the ADC is an antibody in which Ab specifically binds to CD138 as shown in the following (1), the constant region of which is human IgG1, and which comprises a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, and p is 1 to 8.

[0118] More preferably, the ADC is an antibody in which Ab specifically binds to CD138 as shown in the following (1), the constant region of which is human IgG1, and which comprises a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, and p is 3 to 8.

[0119] More preferably, the ADC is an antibody in which Ab specifically binds to CD138 as shown in the following (1), the constant region of which is human IgG1, and which comprises a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, and p is 3 to 5.

[0120] The linker-drug structure and linker structure used in a preferred ADC of the present invention are shown below. In the diagram of the linker, the linker is bound to the antibody on the left side via the dashed line, and to the drug on the right side.

[0121] ADC3, 8-14, 16, 17 (MC-Val-Cit-PAB-MMAE)

[0122] MC-Val-Cit-PAB

[0123] MMAE

[0124] ADC4 (MC-Val-Cit-PAB-MMAF)

[0125] MC-Val-Cit-PAB

[0126] MMAF

[0127] The ADC and antibody of the present invention have stable physical properties as described in the Examples below. Physical properties can be evaluated using various indices related to the susceptibility to denaturation and aggregation, for example, the denaturation midpoint temperature T ｍ 2. Agglomeration start temperature T ａｇｇThe ADC of the present invention is preferably an ADC having stable physical properties, and more preferably has a denaturation midpoint temperature T ｍ 2 is 80°C or higher or the aggregation starting temperature T ａｇｇ 266 is 70°C or higher, and particularly preferably, ｍ 2 is 80°C or higher or the aggregation starting temperature T ａｇｇ 266 is an ADC at 70°C or higher.

[0128] The ADCs and antibodies of the present invention also include pharmaceutically acceptable salts, which include, but are not limited to, inorganic acid salts, organic acid salts, alkali metal salts, alkaline earth metal salts, and organic amine salts.

[0129] Furthermore, when the ADCs and antibodies of the present invention have isomers such as optical isomers, stereoisomers, rotamers, and tautomers, all isomers and mixtures thereof are encompassed unless otherwise specified.

[0130] <Anti-tumor agent> The present invention also includes an anti-tumor agent containing the above-mentioned ADC as an active ingredient.

[0131] The cancers on which the antibody-drug conjugates (ADCs) of the present invention exert an antitumor effect are not particularly limited as long as they express CD138. Specific examples include multiple myeloma, acute myeloid leukemia, gastric cancer, pancreatic cancer, colon cancer, liver cancer, lung cancer, breast cancer, skin cancer, head and neck cancer, oral cancer, laryngeal cancer, esophageal cancer, gallbladder cancer, cervical cancer, uterine cancer, ovarian cancer, mesothelioma, renal cell carcinoma, urothelial cancer, prostate cancer, skin cancer, bone and soft tissue tumors, rhabdomyosarcoma, brain tumors, malignant neurilemmoma, neuroendocrine tumors, and thyroid cancer. Solid cancers are preferred, with gastric cancer, pancreatic cancer, colon cancer, liver cancer, lung cancer, breast cancer, skin cancer, oral cancer, laryngeal cancer, esophageal cancer, and urothelial cancer being particularly preferred.

[0132] The ADC of the present invention is taken up and internalized into the above-mentioned cancer cells, thereby exerting a therapeutic effect.

[0133] The administration route of the antitumor agent containing the ADC of the present invention is not limited, and it can be administered orally, parenterally, or the like. Examples of parenteral administration include intravenous administration, intramuscular administration, and subcutaneous administration. Furthermore, it may be administered transmucosally (e.g., sublingual or buccal administration), transdermal administration, or rectally. Administration may be systemic or localized to cancer tissue. Examples of dosage forms for the formulation include tablets, capsules, pills, powders, granules, and injections. Oral formulations such as tablets, capsules, pills, powders, and granules can be prepared using additives such as excipients such as glucose, sucrose, lactose, and mannitol; disintegrants such as starch and sodium alginate; lubricants such as magnesium stearate and talc; binders such as polyvinyl alcohol, gelatin, and hydroxypropyl cellulose; surfactants such as fatty acid esters; and plasticizers such as glycerin. The injection preparation may contain additives such as water, sugars such as sucrose, sorbitol, xylose, trehalose, and fructose; sugar alcohols such as sorbitol, mannitol, and xylitol; buffers such as phosphate buffer, citrate buffer, and glutamate buffer; and surfactants such as fatty acid esters.

[0134] The dosage of ADC administered to a patient in need of treatment varies depending on the age, sex, severity, etc. of the patient, and can be determined by the attending physician. For example, ADC may be administered at 0.05 to 10 mg / kg body weight, preferably 0.1 to 2 mg / kg body weight per dose. Alternatively, ADC may be administered at a drug equivalent of MMAE or the like at 0.001 nM to 1000 nM, preferably 0.001 nM to 100 nM per dose.

[0135] The dose may be administered once or in divided doses, such as two, three, four or more times per day, at appropriate intervals over a period ranging from one day to several years.

[0136] Antitumor agents containing the ADC of the present invention as an active ingredient can also be used in combination with other antitumor agents or other therapies. In the present invention, "combination" refers to the combined use of two or more active ingredients, and can be determined from the dosage and administration regimen described in the package insert of the pharmaceutical product. Therefore, combination use can also be considered as the use of active ingredients administered as part of a single administration regimen. Therefore, when administering two or more active ingredients to a patient, separate dosage forms may be used for each active ingredient, or some or all of the active ingredients may be formulated and administered in a single dosage form. Furthermore, when separate dosage forms are used for each active ingredient, the active ingredients can be administered simultaneously or sequentially in any order, as long as the beneficial effects of the two drugs working together are achieved. The administration interval between the two drugs in sequential administration can also be appropriately set, as long as the beneficial effects of the two drugs working together are achieved.

[0137] Other therapies include, for example, surgery, radiation therapy, and the like.

[0138] The other antitumor agent is not particularly limited as long as it is a drug used in the treatment of cancer, excluding the ADC of the present invention, and may be a small molecule or a biological preparation such as an antibody. Specific examples include chemotherapeutic agents (alkylating agents, antimetabolites, microtubule agonists, platinum agents, topoisomerase inhibitors, platinum agents, antitumor antibiotics, etc.), molecular targeted drugs (tyrosine kinase inhibitors, mTOR inhibitors, proteasome inhibitors, HDAC inhibitors, CDK inhibitors, PARP inhibitors, etc.), hormone agents, immune checkpoint inhibitors, etc.

[0139] The present invention will be described in detail below with reference to examples, but is not limited thereto. [Example 1: Production of CD138 monoclonal antibodies (mAB) using recombinant DNA methods] cDNA constructs were prepared from the heavy and light chain genes encoding antibodies 1 to 12 listed in Table 2. Each of the cDNA constructs encoding the heavy and light chains was integrated into pcDNA3 plasmid (Life Technologies), and the respective clonal combinations were transfected into HEK293 cells to forcibly express the heavy and light chains. The culture supernatant was filtered through a 0.22 μm filter, followed by Protein A purification and gel filtration purification to obtain anti-CD138 antibodies.

[0140]

[0141] Example 2: Binding of anti-CD138 antibody to cancer cells Human pancreatic cancer cell line AsPC-1 (Dainippon Sumitomo Pharma Co., Ltd.) was washed with PBS and then recovered with Cell Dissociation Solution (Sigma). The number of cells was counted, and 5 × 10 ５The anti-CD138 antibody obtained in Example 1 and Human IgG Isotype Control (Invitrogen) were diluted with autoMACS Running Buffer-MACS Separation Buffer (Miltenyi Biotec) to a final concentration of 0.001 to 100 μg / mL, added to the AsPC-1 cells, and allowed to stand at 4°C for 30 minutes. After reaction with anti-CD138 antibody and human IgG isotype control, cells were washed with PBS (pH 7.4), and goat-anti-human IgG Fc-APC (BioLegend) antibody dissolved in autoMACS Running Buffer-MACS Separation Buffer was added. After secondary antibody reaction, cells were washed with PBS (pH 7.4), and APC signal (MFI: Mean Fluorescence Intensity) was detected using a flow cytometer (CytoFLEX S, Beckman Coulter). As a result, the cell-binding ability of the evaluated antibodies 1 and 3 to 9 to AsPC-1 cells was confirmed (Figure 1). Furthermore, the cell-binding ability of antibodies 7 to 9 to AsPC-1 cells was shown to be inferior to that of antibody 1.

[0142] [Example 3: Prediction of antigenic risk of antibodies] The antigenic risk of antibodies was predicted using In silico Epibase profile (Lonza) based on the amino acid sequences of the variable regions of Antibody 1 and Antibody 10. The results showed that the antigenic risk of Antibody 10 was lower than that of Antibody 1.

[0143] Example 4: Antibody-drug conjugation of anti-CD138 antibody The ADC of the present invention can be prepared by reacting an antibody having an amino group and a sulfhydryl group with a drug linker to be added, using the method described below. The combinations of drug linkers conjugated to the antibody for ADCs obtained using anti-CD138 antibodies are shown in Figures 2-1, 2-2, and 2-3. The produced ADC can be identified by concentrating, buffer exchanging, purifying, measuring the antibody concentration, and measuring the average number of drugs bound per antibody molecule using the following common procedures.

[0144] Common Procedure A: Concentration of Antibody or ADC Solution The antibody or ADC solution was placed in an Amicon Ultra (100,000 MWCO, Millipore Co.) container, and the antibody or ADC solution was concentrated by centrifugation (at 2,000 G to 15,000 G for 5 to 20 minutes) using a centrifuge (himac CF5RE, HITACHI).

[0145] Common Procedure B: Measurement of Antibody Concentration Antibody concentrations were measured using a UV measurement device (Nanodrop 8000, Thermo Fisher Scientific Inc.) according to the method specified by the manufacturer.

[0146] Common Procedure C: Buffer Exchange and Purification of Antibody / ADC A Zeba™ Spin Desalting Column (7K MWCO to 40K MWCO, Cat. 89890, Thermo Scientific) was equilibrated with D-PBS (Nacalai Tesque Inc.) according to the method specified by the manufacturer. After loading the antibody / ADC solution, it was eluted with the amount of D-PBS specified by the manufacturer, and the concentration was measured by common procedure B.

[0147] Common Procedure D: Measurement of the Average Number of Drugs Binding per Antibody Molecule in ADC The drug-antibody ratio was analyzed by native size-exclusion chromatography mass spectrometry (SEC-MS) or hydrophobic interaction chromatography with UV detection (HIV-UV).

[0148] SEC-MS analysis allows for the measurement of the drug-antibody ratio based on the mass change due to the binding of the drug linker to the antibody. 2 mg / mL of ADC was injected into an Acquity LC Xevo G2-S Q Tof MS (Waters Corporation), and the ADC was eluted from the column by isocratic elution (100 mM aqueous ammonium acetate, or 100 mM aqueous ammonium acetate / isopropanol (9 / 1), 20 min). The resulting data was analyzed using MassLynx software (Waters Corporation). The column used was an ACQUITY UPLC Protein BEH SEC Column, 200 Å, 1.7 μm, 4.6 mm×150 mm (Waters), and the measurement was carried out at a flow rate of 0.1 to 0.3 mL / min and a column temperature of 25° C.

[0149] HIC-UV analysis was performed as follows: The sample was diluted to 1 mg / mL with D-PBS(-). 10 μL of this solution was tested by liquid chromatography under the following conditions. The peak areas of each of the sample solutions were measured by automatic integration, and their amounts were calculated by the area percentage method.

[0150] Test conditions Detector: ultraviolet absorption photometer (measurement wavelength: 220 nm) Column: AdvanceBio HIC 4.6 × 100 mm, 3.5 μm (Agilent Technologies) Column temperature: constant temperature around 30°C Mobile phase A: 50 mmol / L sodium phosphate buffer (pH 7.0) Mobile phase B: 2 M ammonium sulfate in 50 mmol / L sodium phosphate buffer (pH 7.0) Mobile phase C: 2-propanol Mobile phase delivery: The mixing ratio of mobile phase A, mobile phase B, and mobile phase C was changed as shown in Table 3 to control the concentration gradient.

[0151] Flow rate: 0.5 mL per minute. Area measurement range: From after the solvent peak to 31 minutes after injection. Reagents and test solutions: 50 mmol / L sodium phosphate buffer (pH 7.0): 3.425 mL of phosphoric acid was added to 980 mL of water and adjusted to pH 7.0 with 5 mol / L NaOH. 2 M ammonium sulfate in 50 mmol / L sodium phosphate buffer (pH 7.0): 132.14 g of ammonium sulfate was dissolved in 500 mL of 50 mmol / L sodium phosphate buffer (pH 7.0). 0.02% (W / V) TWEEN 20: 0.2 g of TWEEN 20 was dissolved in 100 mL of water. 10 mL of this solution was mixed with 90 mL of water.

[0152] [Production Example 1: Antibody-drug conjugate 1 (ADC1)] Step 1: Conjugation of antibody and drug linker To a solution containing 2 mg of antibody 1 prepared in Example 1, a DMSO solution containing 10 mM SMCC-DM1 (MedChemExpress) was added at room temperature so that the amount was 9.6 equivalents per antibody molecule, and DMA (N,N-dimethylacetamide) was added to a final concentration of 10%. The mixture was stirred at room temperature for 24 hours using a rotator to bind the drug linker to the antibody, yielding antibody-drug conjugate 1 (ADC1).

[0153] Step 2: Purification and Characterization The solution containing antibody-drug conjugate 1 (ADC1) obtained in step 1 was purified and its concentration measured by common procedure C, and the following characteristic values ​​were obtained by common procedure D. It was confirmed that no aggregates were detected in the product by dynamic light scattering. Antibody concentration: 1.94 mg / mL, average number of drugs bound per antibody molecule (n): 1.5

[0154] [Production Example 2: Antibody-drug conjugate 2 (ADC2)] Step 1: Conjugation of antibody and drug linker To a solution containing 65 mg of antibody 2 prepared in Example 1, a DMSO solution containing 10 mM SPDB-DM4 (MedChemExpress) was added at room temperature so that the amount was 16 equivalents per antibody molecule, and DMA was added to a final concentration of 10%. The mixture was stirred at room temperature for 24 hours using a rotator to bind the drug linker to the antibody, yielding antibody-drug conjugate 2 (ADC2).

[0155] Step 2: Purification and Characterization The solution containing antibody-drug conjugate 2 (ADC2) obtained in step 1 was purified and its concentration measured by common procedure C, and the following characteristic values ​​were obtained by common procedure D-2. The product was confirmed to contain aggregates by dynamic light scattering. Antibody concentration: 5.66 mg / mL, average number of drugs bound per antibody molecule (n): 2.7

[0156] [Production Examples 3 to 14: Antibody-Drug Conjugates 3 to 14 (ADC3 to 14)] Step 1: Reduction of Antibody A 5 mM aqueous TCEP solution (20 equivalents per antibody molecule) was added to a solution containing antibodies 1, 3 to 6, and 10 to 12 prepared in Example 1, and the solution was incubated at 37°C for 2 hours to reduce the disulfide bond in the hinge region of the antibody.

[0157] Step 2: Conjugation of antibody and drug linker To the solution obtained in step 1, 9.6 equivalents per antibody molecule of any of MC-VC-PAB-MMAE (MedChemExpress), MC-VC-PAB-MMAF (MedChemExpress), MC-GGFG-Dxd (MedChemExpress), MC-GGFG-Dx8951 (MedChemExpress), and MC-VA-PBD (MedChemExpress), dissolved in DMSO to a concentration of 10 mM, was added at room temperature, and the mixture was stirred for 24 hours using a rotator to bind the drug linker to the antibody, thereby obtaining antibody-drug conjugates 3 to 14 (ADC3 to 14) in Figures 2-1, 2-2, and 2-3.

[0158] Step 3: Purification and Characterization The solutions containing antibody-drug conjugates 3 to 14 (ADC3 to 14) obtained in step 2 were purified, concentrated, and their concentrations measured by common procedures A and C, and the characteristic values ​​shown in Table 4 were obtained by common procedure D. In addition, the products were checked for the presence or absence of aggregates by dynamic light scattering, and the results shown in Table 4 were obtained.

[0159]

[0160] Example 5: Ex vivo evaluation of ADC stability in plasma The stability in mouse and human plasma was evaluated for ADC1 to 6 and ADC8 to 14 prepared in Example 4. Step 1: Incubation in plasma Each ADC, adjusted to 1.0 or 0.5 mg / mL, was added to human and BALB / c mouse plasma (anticoagulant: Heparin Na) to a final concentration of 20 or 10 μg / mL, and the mixture was incubated for 48 hours.

[0161] Step 2: Pretreatment: For ADCs containing MMAE or MMAF as the drug, the incubation sample was deproteinized with ethanol, and the free drug was extracted from the ADC. For ADCs containing Dxd or Dx8951 as the drug, the incubation sample was deproteinized with acetonitrile / methanol (9 / 1, v / v), and the extract of the free drug was diluted two-fold with 1% formic acid and incubated for 1 hour. For ADCs containing SMCC-DM1 as the linker / drug, the incubation sample was reduced with TCEP and then deproteinized with acetonitrile / methanol (9 / 1, v / v), and the DM1 released from the ADC was extracted. In the case of ADCs having SPDB-DM4 as a linker / drug, the incubation sample was passed through a MonoSpinProA column (GL Sciences) to extract the ADC. The ADC extract was reduced with TCEP to release DM4 bound to the ADC. The eluate was deproteinized using acetonitrile / methanol (9 / 1, v / v), and DM4 was extracted.

[0162] Step 3: LC / MS / MS Measurement The sample solution pretreated as in step 2 was subjected to LC / MS / MS measurement, and the payload release (%) was calculated using the following formula. In the case of ADCs other than those having SPDB-DM4: For ADCs with SPDB-DM4: As a result, it was found that ADCs 3, 5, 6, 8 to 14 were stable, with payload release in mouse and human plasma being less than 5% (Table 5).

[0163]

[0164] Example 6: Cytotoxicity mediated by ADC Human pancreatic cancer cell line Capan-1 (HSRRB) was washed with PBS and then recovered with Cell Dissociation Solution (Sigma). Human T-cell leukemia Jurkat (JCRB) cells were counted and 1 x 10 ６ Antibody 1 obtained in Example 1 and Human IgG Isotype Control (Invitrogen) were diluted with autoMACS Running Buffer-MACS Separation Buffer (Miltenyi Biotec) to a final concentration of 15 μg / mL, added to Capan-1 and Jurkat, and allowed to stand at room temperature for 30 minutes. After the antibody reaction, the cells were washed with PBS (pH 7.4), and goat-anti-human IgG Fc-APC (BioLegend) antibody dissolved in autoMACS Running Buffer-MACS Separation Buffer was added. After the secondary antibody reaction, the cells were washed with PBS (pH 7.4), and the APC signal (MFI: Mean Fluorescence Intensity) was detected using a flow cytometer (CytoFLEX S, Beckman Coulter). As a result, the cell binding of antibody 1 to Capan-1 cells and its non-binding to Jurkat cells were confirmed (Figure 3).

[0165] ADCs 1 to 14 were prepared using the procedure described in Example 4, and their cytotoxicity against the pancreatic cancer cell line Capan-1 and human T-cell leukemia Jurkat was evaluated using the CellTiter-Glo 2.0 luminescent cell viability assay (Promega). Each cell line was seeded at 1,000 cells / well in a 96-well plate, and the ADCs were added and cultured at 37°C for 5 days. After 5 days, the CellTiter-Glo 2.0 luminescent cell viability assay was added. The relative luminescence intensity was measured using an EnSpire Multimode Plate Reader (PerkinElmer), and the data was analyzed using XLfit software (IDBS). The IC ５０ The cytotoxicity of ADCs 2, 3, 4, and 7 to 14 was determined (Table 6). As a result, ADCs 2, 3, 4, and 7 to 14 exhibited cytotoxicity against Capan-1 cells bound to antibody 1. On the other hand, ADCs 2 and 7 exhibited cytotoxicity against Jurkat cells that did not bind to antibody 1. This was thought to be due to an antigen-independent action. These findings suggest that ADCs 3, 4, and 8 to 14 exhibit antigen-dependent action and are useful as antitumor agents.

[0166]

[0167] Example 7: Antitumor effect of ADC (in vivo) A tumor-bearing animal model was created using a pancreatic cancer (Capan-1) cell line. First, cells were prepared and subcutaneously inoculated (1 x 10 cells) into the right thoracic region of nude mice. ７ (cells / 100 μl). When the volume of the inoculated tumor was 100-300 mm ３ When the tumor size reached approximately 100 mg / kg, the nude mice were randomly assigned to a control group (administered with PBS) and a test group, and the ADC2 was intravenously injected at 1.25 mg / kg, 5 mg / kg, or 20 mg / kg, and the ADC3 was intravenously injected at 20 mg / kg. Weekly administration was used. The tumor size was measured twice a week, and calculated using the following formula: tumor size (mm ３ ) = (long axis x short axis ２ ) / 2

[0168] As shown in Figure 4, tumor growth was suppressed in the ADC3-administered group compared to the control group from day 7 after the start of administration, and tumor shrinkage was also confirmed. Furthermore, no weight loss or other symptoms were observed in the ADC3-administered group. On the other hand, tumor growth was suppressed in the ADC2-administered group at 20 mg / kg, but no antitumor effect was observed at 1.25 mg / kg or 5 mg / kg. Furthermore, a dose-dependent weight loss was observed in the ADC2-administered group. These results demonstrate that the ADC combination of the present invention exhibits a significant tumor growth inhibitory effect compared to the antibody-linker-payload combination of BT062 (ADC2), a prior art technology, and provides an excellent balance between antitumor effect and toxicity.

[0169] Example 8: Antitumor effect of ADC (in vivo) A tumor-bearing animal model was created using a pancreatic cancer (Capan-1) cell line. First, cells were prepared and subcutaneously inoculated (1 x 10 cells) into the right thoracic region of nude mice. ７ (cells / 100 μl). When the volume of the inoculated tumor was 100-200 mm ３ When tumor size reached approximately 100%, nude mice were randomly assigned to a control group (administered with PBS) and a test group, and ADC3, 12, 13, and 14 were intravenously injected at a dose of 1 mg / kg. The administration frequency was weekly. The tumor size was measured twice a week, and the tumor size was calculated using the following formula: tumor size (mm ３ ) = (long axis x short axis ２ ) / 2

[0170] As shown in Figure 5, from day 7 after the start of the study, tumor growth was confirmed to be suppressed in all ADC administration groups compared to the control group. Furthermore, no weight loss was observed in any ADC administration group. These results demonstrate that the combinations of ADC3, 12, 13, and 14 of the present invention have equivalent in vivo antitumor effects.

[0171] [Production Example 15: Antibody-Drug Conjugate 15 (ADC15)] An ADC was prepared according to the production method described in Patent Document 1, using Antibody 2 prepared in Example 1 as the antibody and SPDB-DM4 as the linker and payload. Antibody concentration: 2.71 mg / mL, average number of drugs bound per antibody molecule (n): 3.39 (SEC-MS analysis: DAR0 (4.42%), DAR1 (11.39%), DAR2 (15.97%), DAR3 (20.62%), DAR4 (20.20%), DAR5 (15.78%), DAR6 (8.31%), DAR7 (2.65%), DAR8 (0.67%)).

[0172] Preparation Example 16: Antibody-drug conjugate 16 (ADC16) A solution of antibody 10 (12.02 mg / mL, 32.0 mL) prepared in Example 1 was diluted with 50 mM phosphate buffer (30.2 mL) whose pH had been adjusted to 4.0. ３ P.O. ４ An aqueous solution (6.944 mL) was added. At this time, the pH of the solution was 4.41. A 5 mM D-PBS(-) solution of TCEP·HCl (1.7828 mL) was added to the antibody solution while stirring at room temperature, and the reaction solution was stirred at 37°C for 2 hours. A 10 mM DMSO solution of MC-VC-PAB-MMAE (1.7828 mL) was added and stirred at room temperature for 1 hour. Then, a pH 7 D-PBS(-) solution (72.7 mL) was added to the reaction solution and stirred at room temperature for an additional 1 hour. A 5 mM D-PBS(-) solution of TCEP·HCl (2.0064 mL) was then added. The reaction solution was stirred at 37°C for 1.5 hours, after which a 10 mM DMSO solution of MC-VC-PAB-MMAE (0.8914 mL) was added and stirred at room temperature for 1 hour.

[0173] The resulting reaction solution was filtered using a Merck Millipore Stericup-HV Sterile Vacuum Filtration System (0.45 μm, PVDF). The resulting filtrate was filtered through a Merck Millipore Pellicon XL50 with Ultracel (30 kDa, 0.005 μm). ２) was used to remove low molecular weight impurities by ultrafiltration. The resulting purified solution was filtered using a Merck Millipore Millex GV Syringe filter unit (0.22 μm, Φ33 mm), and ADC16 was obtained as a D-PBS(-) solution. Antibody concentration: 7.91 mg / mL, average number of drugs bound per antibody molecule (n): 3.78 (HIC-UV analysis (area% @ 220 nm): DAR0 (6.85%), DAR2 (27.11%), DAR3 (2.47%), DAR4 (37.59%), DAR5 (2.61%), DAR6 (17.04%), DAR8 (6.31%)).

[0174] Preparation Example 17: Antibody-drug conjugate 17 (ADC17)] Antibody 10 (12.02 mg / mL, 5.0 mL) prepared in Example 1 was diluted with D-PBS(-) (2.0 mL). To the antibody solution was added a 5 mM D-PBS(-) solution of TCEP.HCl (812.18 μL) while stirring at room temperature, and the reaction solution was stirred at 37°C for 1 hour. Thereafter, a 10 mM DMSO solution of MC-VC-PAB-MMAE (422.34 μL) was added, and the mixture was further stirred at room temperature for 1 hour.

[0175] Low molecular weight impurities were removed from the reaction solution by gel filtration using a Zeba Spin Desalting Column (40K MWCO, 10 mL, 6 tubes) manufactured by ThermoScientific. The resulting column eluates were combined and concentrated to approximately 6 mL using an Amicon Ultra-15 (10K MWCO) manufactured by Merck Millipore. The concentrate was repurified using a Zeba Spin Desalting Column. The resulting column eluates were combined and filtered through a Merck Millipore Millex GV Syringe filter unit (0.22 μm, Φ33 mm) to obtain ADC17 as a D-PBS(-) solution. Antibody concentration: 5.61 mg / mL, average number of drugs bound per antibody molecule (n): 7.91 (HIC-UV analysis (area% @ 220 nm): DAR 6 (3.30%), DAR 8 (96.34%))

[0176] Example 9: ADC-mediated cytotoxicity The cytotoxicity of ADC15, 16, and 17 against the pancreatic cancer cell line BxPC-3 and human T-cell leukemia Jurkat was evaluated using a CellTiter-Glo 2.0 luminescent cell viability assay (Promega). BxPC-3 cells were seeded at 350 cells / well and Jurkat cells at 150 cells / well in a 384-well plate, and ADC16 and 17 were added, respectively, followed by incubation at 37°C for 5 days. After 5 days, CellTiter-Glo 2.0 luminescent cell viability assay was added. The relative light intensity was measured using an EnSpire Multimode Plate Reader (PerkinElmer), and the data was analyzed using a 4 Parameter Logistic Model to determine the IC50 for each cancer cell line. The results are shown in Table 7. Both ADC16 and 17 exhibited cytotoxicity against CD138-positive BxPC-3 cells, while not against CD138-negative Jurkat cells. This suggests that both ADC16 and 17 exhibited cytotoxicity through antigen-dependent activity. ADC16 and ADC17 share the same antibody, linker, and payload, differing only in the number of drugs bound to one antibody molecule (ADC16: 3.78, ADC17: 7.91), but the antigen-dependent activity in their cytotoxicity was believed to be maintained.

[0177]

[0178] Example 10: Evaluation of ADC Stability ADC15, ADC16, and ADC17 were prepared in phosphate-buffered saline (Dulbecco's PBS, pH 7.4) to a concentration of approximately 2.71 mg / mL, 7.91 mg / mL, and 5.61 mg / mL, respectively. The denaturation midpoint temperature, aggregation onset temperature, and particle size distribution of these various antibody solutions were determined using a protein physical property evaluation device, UNcle (manufactured by UNCHAINED LABS, Inc.). Specifically, to measure the denaturation midpoint temperature and aggregation onset temperature, the various antibodies were heated from 25°C to 95°C by 1°C per minute, and fluorescence spectroscopy and static light scattering measurements were simultaneously performed over time. Based on the results of the fluorescence spectroscopy, the midpoint temperature of the peak centroid shift in the fluorescence spectrum of the endogenous amino acids of the antibody was determined (n=3) by utilizing the phenomenon that the denaturation of the antibody causes a shift in the peak centroid. Furthermore, based on the results of static light scattering measurements, the scattering intensity increases upon aggregation, and the temperature at which the scattered light at 266 nm begins to increase, i.e., the aggregation onset temperature, was determined (n=3).

[0179] Furthermore, ADC15 (2.71 mg / mL), ADC16 (7.91 mg / mL), and ADC17 (5.61 mg / mL) were prepared in phosphate-buffered saline (Dulbecco's PBS, pH 7.4), and the molecular sizes were measured over time by dynamic light scattering every 30 minutes after storage at 50°C for 48 hours. The difference between the initial average molecular size and the value after 48 hours was calculated to evaluate the aggregation properties (n=3).

[0180] The results are shown in Table 8.

[0181] It was revealed that ADC16 and ADC17 have higher denaturation midpoint temperatures and aggregation onset temperatures than ADC15 described in Patent Document 1. The denaturation midpoint temperature and aggregation onset temperature are known to be related to long-term storage stability, and the above results demonstrate the high stability of the ADC of the present invention.

[0182] Furthermore, when actually stored at 50°C for 48 hours, ADC16 and ADC17 showed a smaller increase in average molecular size compared to ADC15 described in Patent Document 1, demonstrating the low aggregation tendency of the ADC of the present invention.

[0183] When a similar test was carried out using only the antibodies, Antibodies 10 to 12 showed superior stability to Antibodies 1 and 2, as in the above results.

[0184] From the above, the antibodies and ADCs of the present invention exhibit excellent stability even when heated, and are useful as pharmaceuticals or raw materials thereof.

[0185] SEQ ID NO: 1: Amino acid sequence of CDR1 of the heavy chain of antibodies 1 to 12 SEQ ID NO: 2: Amino acid sequence of CDR2 of the heavy chain of antibodies 1 to 12 SEQ ID NO: 3: Amino acid sequence of CDR3 of the heavy chain of antibodies 1 to 12 SEQ ID NO: 4: Amino acid sequence of CDR1 of the light chain of antibodies 1 to 12 SEQ ID NO: 5: Amino acid sequence of CDR2 of the light chain of antibodies 1 to 12 SEQ ID NO: 6: Amino acid sequence of CDR3 of the light chain of antibodies 1 to 12 SEQ ID NO: 7: Nucleotide sequence of cDNA encoding the heavy chain variable region of antibody 1 SEQ ID NO: 8: Amino acid sequence of the heavy chain variable region of antibody 1 SEQ ID NO: 9: Nucleotide sequence of cDNA encoding the light chain variable region of antibodies 1 and 2 SEQ ID NO: 10: Amino acid sequence of the light chain variable region of antibodies 1 and 2 SEQ ID NO: 11: Nucleotide sequence of cDNA encoding the heavy chain variable region of antibody 2 SEQ ID NO: 12: Amino acid sequence of the heavy chain variable region of antibody 2 SEQ ID NO: 13: Nucleotide sequence of cDNA encoding the heavy chain variable region of antibody 3 and antibody 10. SEQ ID NO: 14: Amino acid sequence of the heavy chain variable region of antibody 3 and antibody 10. SEQ ID NO: 15: Nucleotide sequence of cDNA encoding the light chain variable region of antibodies 3 to 6 and antibodies 10 to 12. SEQ ID NO: 16: Amino acid sequence of the light chain variable region of antibodies 3 to 6 and antibodies 10 to 12. SEQ ID NO: 17: Nucleotide sequence of cDNA encoding the heavy chain variable region of antibodies 4, 7 and 11. SEQ ID NO: 18: Amino acid sequence of the heavy chain variable region of antibodies 4, 7 and 11. SEQ ID NO: 19: Nucleotide sequence of cDNA encoding the heavy chain variable region of antibodies 5 and 8. SEQ ID NO: 20: Amino acid sequence of the heavy chain variable region of antibodies 5 and 8. SEQ ID NO: 21: Nucleotide sequence of cDNA encoding the heavy chain variable region of antibodies 6, 9 and 12. SEQ ID NO: 22: Amino acid sequence of the heavy chain variable region of antibodies 6, 9 and 12. SEQ ID NO: 23: Nucleotide sequence of cDNA encoding the variable region of the light chain of Antibody 7 to Antibody 9 SEQ ID NO: 24: Amino acid sequence of the variable region of the light chain of Antibody 7 to Antibody 9 SEQ ID NO: 25: Full-length nucleotide sequence of the heavy chain of Antibody 1 SEQ ID NO: 26: Full-length amino acid sequence of the heavy chain of Antibody 1 SEQ ID NO: 27: Full-length nucleotide sequence of the light chain of Antibody 1 and Antibody 2 SEQ ID NO: 28: Full-length amino acid sequence of the light chain of Antibody 1 and Antibody 2SEQ ID NO: 29: Full length nucleotide sequence of the heavy chain of antibody 2 SEQ ID NO: 30: Full length amino acid sequence of the heavy chain of antibody 2 SEQ ID NO: 31: Full length nucleotide sequence of the heavy chain of antibody 3 SEQ ID NO: 32: Full length amino acid sequence of the heavy chain of antibody 3 SEQ ID NO: 33: Full length nucleotide sequence of the light chain of antibodies 3 to 6 and 10 to 12 SEQ ID NO: 34: Full length amino acid sequence of the light chain of antibodies 3 to 6 and 10 to 12 SEQ ID NO: 35: Full length nucleotide sequence of the heavy chain of antibodies 4 and 7 SEQ ID NO: 36: Full length amino acid sequence of the heavy chain of antibodies 4 and 7 SEQ ID NO: 37: Full length nucleotide sequence of the heavy chain of antibodies 5 and 8 SEQ ID NO: 38: Full length amino acid sequence of the heavy chain of antibodies 5 and 8 SEQ ID NO: 39: Full length nucleotide sequence of the heavy chain of antibodies 6 and 9 SEQ ID NO: 40: Full length amino acid sequence of the heavy chain of antibodies 6 and 9 SEQ ID NO: 41: Full length nucleotide sequence of the light chain of antibodies 7 to 9 SEQ ID NO: 42: Full length amino acid sequence of the light chain of antibodies 7 to 9 SEQ ID NO: 43: Full length nucleotide sequence of the heavy chain of antibody 10 SEQ ID NO: 44: Full length amino acid sequence of the heavy chain of antibody 10 SEQ ID NO: 45: Full length nucleotide sequence of the heavy chain of antibody 11 SEQ ID NO: 46: Full length amino acid sequence of the heavy chain of antibody 11 SEQ ID NO: 47: Full length nucleotide sequence of the heavy chain of antibody 12 SEQ ID NO: 48: Full length amino acid sequence of the heavy chain of antibody 12 SEQ ID NO: 49: Amino acid sequence of human CD138 protein SEQ ID NO: 50: Specific epitope sequence in CD138 All publications, patents and patent applications cited herein are hereby incorporated by reference in their entirety.

Claims

1. An antibody-drug conjugate (ADC) represented by the following general formula 1: Ab-(L-D)p (1) [wherein Ab is any one of the following (1) to (3) selected from the group consisting of an antibody that specifically binds to CD138, the constant region of which is human IgG1, (1) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO:

16. (2) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 18, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO:

16. (3) an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 22, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO:

16. L is a linker, D is monomethylauristatin, and p is 1 to 12.] 2. The antibody-drug conjugate (ADC) according to claim 1, wherein Ab is any one selected from the group consisting of the following (1) to (3): (1) an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO:44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO:34, or an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO:14 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO:44, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO:16 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO:34, and having specific binding ability to CD138. (2) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 46 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody comprising a heavy chain consisting of a variable region consisting of the amino acid sequence shown in SEQ ID NO: 18 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 46, and a light chain consisting of a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34, and having a specific binding ability to CD138. (3) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 48 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 22 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 48, and a light chain consisting of a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34, and having a specific binding ability to CD138.

3. The antibody-drug conjugate (ADC) according to claim 1 or 2, wherein Ab is any one selected from the group consisting of the following (1) to (3): (1) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44, and a light chain consisting of the amino acid sequence shown in SEQ ID NO:

34. (2) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 46, and a light chain consisting of the amino acid sequence shown in SEQ ID NO:

34. (3) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 48, and a light chain consisting of the amino acid sequence shown in SEQ ID NO:

34.

4. The antibody-drug conjugate (ADC) of any one of claims 1 to 3, wherein L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB).

5. The antibody-drug conjugate (ADC) of any one of claims 1 to 4, wherein D is monomethylauristatin E.

6. The antibody-drug conjugate (ADC) of any one of claims 1 to 5, wherein p is 1 to 8.

7. The antibody-drug conjugate (ADC) of any one of claims 1 to 6, wherein Ab is an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO:14, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO:16, L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB), D is monomethylauristatin E, and p is 1 to 8.

8. The antibody-drug conjugate (ADC) of any one of claims 1 to 7, wherein Ab is an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO:44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO:34, L is 6-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-Val-Cit-PAB), D is monomethylauristatin E, and p is 1 to 8.

9. A pharmaceutical composition comprising the antibody-drug conjugate (ADC) according to any one of claims 1 to 8 and a carrier.

10. An antitumor agent comprising the antibody-drug conjugate (ADC) according to any one of claims 1 to 8.

11. The antitumor agent according to claim 10 for treating a cancer in which CD138 is expressed.

12. The antitumor agent according to claim 10, which is administered in combination with other antitumor agents.

13. The antitumor agent according to claim 10 for treating gastric cancer, pancreatic cancer, colon cancer, lung cancer, breast cancer or urothelial cancer.

14. An antibody that specifically binds to CD138, which is any one of the group consisting of (1) to (3) below, wherein the constant region of the antibody is human IgG1: (1) An antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 14, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO:

16. (2) An antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 18, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO:

16. (3) An antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO: 22, and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO:

16.

15. The antibody according to claim 14, which is any one selected from the group consisting of the following (1) to (3): (1) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO:44 and a light chain consisting of the amino acid sequence shown in SEQ ID NO:34, or an antibody comprising a heavy chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO:14 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO:44 and a light chain comprising a variable region consisting of the amino acid sequence shown in SEQ ID NO:16 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO:34, and having specific binding ability to CD138. (2) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 46 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody comprising a heavy chain consisting of a variable region consisting of the amino acid sequence shown in SEQ ID NO: 18 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 46, and a light chain consisting of a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34, and having a specific binding ability to CD138. (3) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 48 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 34, or an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 22 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 48, and a light chain consisting of a variable region consisting of the amino acid sequence shown in SEQ ID NO: 16 and having at least 98% sequence identity with the amino acid sequence shown in SEQ ID NO: 34, and having a specific binding ability to CD138.

16. The antibody according to claim 14 or 15, which is any one selected from the group consisting of the following (1) to (3): (1) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 44, and a light chain consisting of the amino acid sequence shown in SEQ ID NO:

34. (2) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 46, and a light chain consisting of the amino acid sequence shown in SEQ ID NO:

34. (3) An antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 48, and a light chain consisting of the amino acid sequence shown in SEQ ID NO:

34.

17. A method for treating cancer, comprising the step of administering to a subject an antibody-drug conjugate (ADC) according to any one of claims 1 to 8.

18. Use of an antibody-drug conjugate (ADC) according to any one of claims 1 to 8 for the treatment of cancer.

19. An antibody-drug conjugate (ADC) according to any one of claims 1 to 8 for use in the treatment of cancer.

20. Use of an antibody-drug conjugate (ADC) according to any one of claims 1 to 8 for the manufacture of an antitumor agent.

21. A method for treating cancer, comprising the step of administering to a subject an antibody-drug conjugate (ADC) according to any one of claims 1 to 8 and another anti-tumor agent.

22. Use of an antibody-drug conjugate (ADC) according to any one of claims 1 to 8 for the treatment of cancer, said ADC being administered in combination with other antitumor agents.

23. An antibody-drug conjugate (ADC) according to any one of claims 1 to 8 for use in the treatment of cancer, said ADC being administered in combination with another anti-tumor agent.

24. Use of an antibody-drug conjugate (ADC) according to any one of claims 1 to 8 for the manufacture of an antitumor agent to be administered in combination with another antitumor agent.