Anti-b7-h3 antibody and medical use thereof

Abstract

Provided are an anti-B7-H3 antibody and a medical use thereof. Specifically, provided is the use of an anti-B7-H3 antibody in the preparation of a medication for treating or preventing a disease or condition associated with B7-H3.

Description

Anti-b7-h3 antibodies and medical uses thereof

[0001] This application claims priority to Chinese Patent Application CN202411286229.6 filed on September 13, 2024 and Chinese Patent Application CN202510527780.3 filed on April 25, 2025. TECHNICAL FIELD

[0002] The present disclosure is in the field of biotechnology, and more specifically, the present disclosure relates to anti-B7-H3 antibodies and medical uses thereof. BACKGROUND

[0003] The statements herein are provided only to provide background information related to the present disclosure and do not necessarily constitute the prior art.

[0004] B7-H3, also known as CD276, belongs to single transmembrane protein, with a full length of about 54KD; the extracellular domain of B7-H3 is composed of two tandem repeated IgV / C domains, which are IgV1-IgC1-IgV2-IgC2; in the human body, B7-H3 exists in the form of 4Ig domain and 2Ig domain (Vigdorovich, V., et al. Structure, 2013, 21(5): 707-717; Sutton, M.N., et al. Communications biology, 7(1): 21). B7-H3 belongs to the B7 / CD28 immune checkpoint family, can bind to the receptor on T cells to help tumor achieve immune escape, but the receptor of B7H3 on T cells has not been confirmed, and its sequence similarity with PD-L1 (B7-H1) and PD-L2 (B7-DC) in the same family is about 29%, 26% (Wang, C., et al. Cell stem cell, 2021, 28(9): 1597-1613). B7-H3 also plays a role of co-stimulation or co-inhibition in immune regulation, can act as an inhibitory receptor of NK cells and T cells, help tumor achieve immune escape, and also can act as a co-stimulatory factor to promote the response to inflammation and enhance the production of pro-inflammatory factors in inflammatory response (Tyagi, A., et al. Blood, 2022, 139(18): 2782-2796). On the other hand, B7-H3 is overexpressed in a variety of tumors, especially lung cancer, breast cancer, ovarian cancer, prostate cancer, esophageal cancer, pancreatic cancer, endometrial cancer, gastric cancer, melanoma, liver cancer, colorectal cancer, etc.; in normal tissues, such as liver, adrenal gland, prostate, testis, ovary, lung and skin, etc., it presents a low expression level (Bottino, C., et al. Cancers, 2023, 15(13): 3279; Sutton, M.N., et al. Communications biology, 7(1): 21).

[0005] WO2011109400A2, WO2012147713A1, WO2018177393A1 and other patents disclose anti-B7-H3 antibodies, but no anti-B7-H3 antibody drug has been approved for marketing. SUMMARY

[0006] <Anti-B7-H3 antibody>

[0007] The present disclosure provides an anti-B7-H3 antibody comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises HCDR1, HCDR2 and HCDR3, and the light chain variable region comprises LCDR1, LCDR2 and LCDR3, wherein:

[0008] (1) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 14, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 15, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 16, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 17, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 90, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 19, wherein:

[0009] YTSRLHX1 SEQ ID NO: 90;

[0010] X1is S or E; or

[0011] (2) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 8, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 88, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 89, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 13, wherein:

[0012] NINPFX2GGTNYNEKFKS SEQ ID NO: 88;

[0013] RSSQTIVRSX3GX4TYLE SEQ ID NO: 89;

[0014] X2is Q or N;

[0015] X3is E or D; X4is N or Q; or

[0016] (3) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 93, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 144, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 95, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 145, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 146, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 98, wherein:

[0017] WIYPRDASX5YSERFKD SEQ ID NO: 144;

[0018] RSSKSLX6HSNGX7TYLF SEQ ID NO: 145;

[0019] QMSNLAX8 SEQ ID NO: 146;

[0020] X5 is Q or N;

[0021] X6 is T or L;

[0022] X7 is I or H;

[0023] X8 is T or S.

[0024] The disclosure provides an anti-B7-H3 antibody comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises a HCDR1, a HCDR2, and a HCDR3, and the light chain variable region comprises a LCDR1, a LCDR2, and a LCDR3, wherein:

[0025] (1) the HCDR1, the HCDR2, and the HCDR3 of the heavy chain variable region comprise the amino acid sequences of the HCDR1, the HCDR2, and the HCDR3 in SEQ ID NO: 69, 64, 65, 66, 67, or 68, respectively, and the LCDR1, the LCDR2, and the LCDR3 of the light chain variable region comprise the amino acid sequences of the LCDR1, the LCDR2, and the LCDR3 in SEQ ID NO: 70, 71, 72, 73, 74, or 75, respectively; or

[0026] the HCDR1, the HCDR2, and the HCDR3 of the heavy chain variable region comprise the amino acid sequences of the HCDR1, the HCDR2, and the HCDR3 in SEQ ID NO: 22, respectively, and the LCDR1, the LCDR2, and the LCDR3 of the light chain variable region comprise the amino acid sequences of the LCDR1, the LCDR2, and the LCDR3 in SEQ ID NO: 23, respectively; or

[0027] (2) the HCDR1, the HCDR2, and the HCDR3 of the heavy chain variable region comprise the amino acid sequences of the HCDR1, the HCDR2, and the HCDR3 in SEQ ID NO: 40, 33, 41, 34, 35, 36, 37, 38, or 39, respectively, and the LCDR1, the LCDR2, and the LCDR3 of the light chain variable region comprise the amino acid sequences of the LCDR1, the LCDR2, and the LCDR3 in SEQ ID NO: 47, 42, 45, 46, 43, or 44, respectively; or

[0028] the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of the HCDR1, HCDR2, and HCDR3, respectively, in SEQ ID NO: 20, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of the LCDR1, LCDR2, and LCDR3, respectively, in SEQ ID NO: 21; or

[0029] (3) the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of the HCDR1, HCDR2, and HCDR3, respectively, in SEQ ID NO: 125, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of the LCDR1, LCDR2, and LCDR3, respectively, in SEQ ID NO: 127, 126, or 128; or

[0030] the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of the HCDR1, HCDR2, and HCDR3, respectively, in SEQ ID NO: 99, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of the LCDR1, LCDR2, and LCDR3, respectively, in SEQ ID NO: 100.

[0031] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0032] (1) the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of the HCDR1, HCDR2, and HCDR3, respectively, in SEQ ID NO: 66, 69, 64, or 65, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of the LCDR1, LCDR2, and LCDR3, respectively, in SEQ ID NO: 71, 70, 72, 73, 74, or 75; or

[0033] the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of the HCDR1, HCDR2, and HCDR3, respectively, in SEQ ID NO: 22, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of the LCDR1, LCDR2, and LCDR3, respectively, in SEQ ID NO: 23; or

[0034] (2) the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 in SEQ ID NO: 40, 33, or 41, respectively, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 in SEQ ID NO: 47, 42, 45, or 46, respectively; or

[0035] the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 in SEQ ID NO: 20, respectively, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 in SEQ ID NO: 21, respectively; or

[0036] (3) the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 in SEQ ID NO: 125, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124, respectively, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 in SEQ ID NO: 127, 126, or 128, respectively; or

[0037] the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 in SEQ ID NO: 99, respectively, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 in SEQ ID NO: 100, respectively.

[0038] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0039] (1) the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 in SEQ ID NO: 69, respectively, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 in SEQ ID NO: 70, respectively; or

[0040] (2) the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3, respectively, in SEQ ID NO: 40, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3, respectively, in SEQ ID NO: 47.

[0041] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0042] (1) the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3, respectively, in SEQ ID NO: 66, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3, respectively, in SEQ ID NO: 71; or

[0043] (2) the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3, respectively, in SEQ ID NO: 40, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3, respectively, in SEQ ID NO: 47; or

[0044] (3) the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3, respectively, in SEQ ID NO: 125, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3, respectively, in SEQ ID NO: 127.

[0045] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2, and LCDR3 of the light chain variable region are defined according to the numbering rules selected from Kabat, IMGT, Chothia, AbM, and Contact. In some embodiments, the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2, and LCDR3 of the light chain variable region are defined according to the Kabat numbering rules. In some embodiments, the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2, and LCDR3 of the light chain variable region are defined according to the IMGT numbering rules. In some embodiments, the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2, and LCDR3 of the light chain variable region are defined according to the Chothia numbering rules. In some embodiments, the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2, and LCDR3 of the light chain variable region are defined according to the AbM numbering rules. In some embodiments, the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2, and LCDR3 of the light chain variable region are defined according to the Contact numbering rules.

[0046] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0047] (1) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 14, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 15, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 16, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 17, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 18 or 63, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 19; or

[0048] (2) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 8, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 32 or 9, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 30, 11, or 31, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 13; or

[0049] (3) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 93, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 114 or 94, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 95, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 111, 96, or 113, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 112 or 97, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 98.

[0050] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0051] (1) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 14, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 15, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 16, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 17, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 18 or 63, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 19; or

[0052] (2) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 8, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 32, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 30, 11, or 31, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 13; or

[0053] the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 8, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 9, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 11, 30, or 31, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 13; or

[0054] (3) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:93, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 114, and the HCDR3 comprises the amino acid sequence of SEQ ID NO:95, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 111 or 113, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 112, and the LCDR3 comprises the amino acid sequence of SEQ ID NO:98; or

[0055] the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:93, the HCDR2 comprises the amino acid sequence of SEQ ID NO:94 or 114, and the HCDR3 comprises the amino acid sequence of SEQ ID NO:95, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO:96, the LCDR2 comprises the amino acid sequence of SEQ ID NO:97, and the LCDR3 comprises the amino acid sequence of SEQ ID NO:98.

[0056] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0057] (1) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 14, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 15, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 16, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 17, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 18, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 19; or

[0058] (2) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:8, the HCDR2 comprises the amino acid sequence of SEQ ID NO:32, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO:30, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 13; or

[0059] (3) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 93, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 114, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 95, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 111, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 112, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 98.

[0060] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2, and LCDR3 of the light chain variable region are defined according to the Rabat numbering convention.

[0061] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein the anti-B7-H3 antibody is a murine, chimeric, humanized, or fully human antibody. In some embodiments, the anti-B7-H3 antibody is a murine, chimeric, or humanized antibody. In some embodiments, the anti-B7-H3 antibody is a chimeric or humanized antibody. In some embodiments, the anti-B7-H3 antibody is a humanized antibody.

[0062] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, comprises a framework region (FR) of a human antibody.

[0063] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, the heavy chain variable region has a FR1, FR2, FR3 derived from IGHV1-69*02, and a FR4 derived from IGHJ1*01, and which is unsubstituted or comprises one or more amino acid substitutions selected from the group consisting of 1E, 27H, 37M, 40R, and 94S; and / or the light chain variable region has a FR1, FR2, FR3 derived from IGKV1-39*01, and a FR4 derived from IGKJ4*01, and which is unsubstituted or comprises one or more amino acid substitutions selected from the group consisting of 41D, 42G, 43T, 44V, and 71Y. In some embodiments, the anti-B7-H3 antibody, wherein the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 14, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 15, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 16, and the FR of the heavy chain variable region is unsubstituted or comprises one or more amino acid substitutions selected from the group consisting of 1E, 27H, 37M, 40R, and 94S; and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 17, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 18 or 63, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 19, and the FR of the light chain variable region is unsubstituted or comprises one or more amino acid substitutions selected from the group consisting of 41D, 42G, 43T, 44V, and 71Y. In some embodiments, the above variable regions and CDRs are defined according to the Kabat numbering convention.

[0064] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, the heavy chain variable region has a FR1, FR2, FR3 derived from IGHV1-46*01 and a FR4 derived from IGHJ6*01, and which is unsubstituted or comprises one or more amino acid substitutions selected from the group consisting of 1E, 40R, 69L, 71V, 73K, 78A, 80I, and 93T; and / or the light chain variable region has a FR1, FR2, FR3 derived from IGKV2-29*02 and a FR4 derived from IGKJ2*01, and which is unsubstituted or comprises one or more amino acid substitutions selected from the group consisting of 2V and 45K. In some embodiments, the anti-B7-H3 antibody, wherein the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 8, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 32 or 9, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and the FR of the heavy chain variable region is unsubstituted or comprises one or more amino acid substitutions selected from the group consisting of 1E, 40R, 69L, 71V, 73K, 78A, 80I, and 93T; and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 30, 11, or 31, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 13, and the FR of the light chain variable region is unsubstituted or comprises one or more amino acid substitutions selected from the group consisting of 2V and 45K. In some embodiments, the above variable regions and CDRs are defined according to the Kabat numbering convention.

[0065] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, the heavy chain variable region has a FR1, FR2, FR3 derived from IGHV1-46*01, and a FR4 derived from IGHJ6*01, and which is either unsubstituted or comprises one or more amino acid substitutions selected from the group consisting of 1E, 38K, 40R, 66K, 69L, 71V, 76T, 78T, 82aH, and / or 83T; and / or the light chain variable region has a FR1, FR2, FR3 derived from IGKV2-28*01, and a FR4 derived from IGKJ4*01, and which is unsubstituted. In some embodiments, the anti-B7-H3 antibody, wherein the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 93, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 114 or 94, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 95, and the FR of the heavy chain variable region is unsubstituted or comprises one or more amino acid substitutions selected from the group consisting of 1E, 38K, 40R, 66K, 69L, 71V, 76T, 78T, 82aH, and / or 83T; and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 111, 96, or 113, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 112 or 97, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 98, and the FR of the light chain variable region is unsubstituted. In some embodiments, the above variable regions and CDRs are defined according to the Kabat numbering convention.

[0066] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0067] (1) the heavy chain variable region comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 66, 69, 64, 65, 67, or 68, and the light chain variable region comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 71, 70, 72, 73, 74, or 75; or

[0068] the heavy chain variable region comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 22, and the light chain variable region comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 23; or

[0069] (2) the heavy chain variable region comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 40, 33, 41, 34, 35, 36, 37, 38, or 39, and the light chain variable region comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 47, 42, 45, 46, 43, or 44; or

[0070] the heavy chain variable region comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 20, and the light chain variable region comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 21; or

[0071] (3) the heavy chain variable region comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 125, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124, and the light chain variable region comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 127, 126, or 128; or

[0072] the heavy chain variable region comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 99, and the light chain variable region comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 100.

[0073] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0074] (1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 66, 69, 64, 65, 67, or 68, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 71, 70, 72, 73, 74, or 75; or

[0075] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 22, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 23; or

[0076] (2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, 33, 41, 34, 35, 36, 37, 38, or 39, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 47, 42, 45, 46, 43, or 44; or

[0077] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 20, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 21; or

[0078] (3) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 125, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 127, 126, or 128; or

[0079] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 99, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 100.

[0080] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0081] (1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 66, 64, 65, 67, 68, or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 71; or

[0082] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 69, 64, 65, 66, 67, or 68, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 70; or

[0083] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 64, 65, 66, 67, 68, or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 72; or

[0084] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 64, 65, 66, 67, 68, or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 73; or

[0085] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 64, 65, 66, 67, 68, or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 74; or

[0086] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 64, 65, 66, 67, 68, or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 75; or

[0087] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 22, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 23; or

[0088] (2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 47; or

[0089] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 34, 35, 36, 37, 38, 39, 40, or 41, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 42; or

[0090] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 34, 35, 36, 37, 38, or 39, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 43; or

[0091] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 40, or 41, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 46; or

[0092] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 40, or 41, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 46; or

[0093] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 40, or 41, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 46; or

[0094] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 20, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 21; or

[0095] (3) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 125, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 127 or 128; or

[0096] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, or 125, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 126; or

[0097] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 99, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 100.

[0098] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0099] (1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 66 or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 71; or

[0100] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 69, 64, or 65, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 70; or

[0101] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 66, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 72; or

[0102] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 73; or

[0103] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 64, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 74; or

[0104] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 75; or

[0105] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 22, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 23; or

[0106] (2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 47; or

[0107] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 40, or 41, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 42; or

[0108] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 45; or

[0109] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 46; or

[0110] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 20, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 21; or

[0111] (3) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 125, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 127 or 128; or

[0112] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, or 125, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 126; or

[0113] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 99, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 100.

[0114] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0115] (1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 70; or

[0116] (2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 47.

[0117] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0118] (1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 66, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 71; or

[0119] (2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 47; or

[0120] (3) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 125, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 127.

[0121] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein the anti-B7-H3 antibody is an antibody fragment. In some embodiments, the antibody fragment is selected from the group consisting of a Fab, Fab', F(ab')2, Fd, Fv, scFv, and dsFv.

[0122] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein the antibody comprises a heavy chain constant region and a light chain constant region. In some embodiments, the heavy chain constant region is a heavy chain constant region of human IgGl, IgG2, IgG3, IgG4, or a variant thereof, and the light chain constant region is a light chain constant region of human kappa chain, lambda chain, or a variant thereof. In some embodiments, the heavy chain constant region is a human IgGl heavy chain constant region or a variant thereof, and the light chain constant region is a human kappa light chain constant region or a variant thereof. In some embodiments, the heavy chain constant region comprises amino acid mutations of L234A and L235A, and the light chain constant region is a human kappa light chain constant region. In some embodiments, the heavy chain constant region comprises amino acid mutations of L234A and L235A, and the light chain constant region is a human kappa light chain constant region. In some embodiments, the heavy chain constant region is a human IgGl heavy chain constant region, and the light chain constant region is a human kappa light chain constant region. In some embodiments, the heavy chain constant region comprises the amino acid sequence of SEQ ID NO: 24 or 91, and the light chain constant region comprises the amino acid sequence of SEQ ID NO: 25. In some embodiments, the heavy chain constant region comprises the amino acid sequence of SEQ ID NO: 24, and the light chain constant region comprises the amino acid sequence of SEQ ID NO: 25. In some embodiments, the heavy chain constant region comprises the amino acid sequence of SEQ ID NO: 91, and the light chain constant region comprises the amino acid sequence of SEQ ID NO: 25.

[0123] Unless otherwise indicated, in the disclosure, the position of an amino acid in an antibody variable region is defined according to the Kabat numbering convention, and the position of an amino acid in an antibody constant region is defined according to the Eu index.

[0124] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein the anti-B7-H3 antibody comprises a heavy chain and a light chain, wherein:

[0125] (1) the heavy chain comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 78, 81, 76, 77, 79, or 80, and the light chain comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 83, 82, 84, 85, 86, or 87; or

[0126] the heavy chain comprises an amino acid sequence that has at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 28, and the light chain comprises an amino acid sequence that has at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 29; or

[0127] the heavy chain comprises an amino acid sequence that has at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 108, and the light chain comprises an amino acid sequence that has at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 83; or

[0128] (2) the heavy chain comprises an amino acid sequence that has at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 55, 48, 49, 50, 51, 52, 53, 54, or 56, and the light chain comprises an amino acid sequence that has at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 62, 57, 58, 59, 60, or 61; or

[0129] the heavy chain comprises an amino acid sequence that has at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 26, and the light chain comprises an amino acid sequence that has at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 27; or

[0130] the heavy chain comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 105, and the light chain comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 62; or

[0131] (3) the heavy chain comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 139, 129, 130, 131, 132, 133, 134, 135, 136, 137, or 138, and the light chain comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 141, 140, or 142; or

[0132] the heavy chain comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 101, and the light chain comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 102; or

[0133] the heavy chain comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 143, and the light chain comprises an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to SEQ ID NO: 141.

[0134] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0135] (1) the heavy chain comprises the amino acid sequence of SEQ ID NO: 78, 81, 76, 77, 79, or 80, and the light chain comprises the amino acid sequence of SEQ ID NO: 83, 82, 84, 85, 86, or 87; or

[0136] the heavy chain comprises the amino acid sequence of SEQ ID NO: 28, and the light chain comprises the amino acid sequence of SEQ ID NO: 29; or

[0137] the heavy chain comprises the amino acid sequence of SEQ ID NO: 108, and the light chain comprises the amino acid sequence of SEQ ID NO: 83; or

[0138] (2) the heavy chain comprises the amino acid sequence of SEQ ID NO: 55, 48, 49, 50, 51, 52, 53, 54, or 56, and the light chain comprises the amino acid sequence of SEQ ID NO: 62, 57, 58, 59, 60, or 61; or

[0139] the heavy chain comprises the amino acid sequence of SEQ ID NO: 26, and the light chain comprises the amino acid sequence of SEQ ID NO: 27; or

[0140] the heavy chain comprises the amino acid sequence of SEQ ID NO: 105, and the light chain comprises the amino acid sequence of SEQ ID NO: 62; or

[0141] (3) the heavy chain comprises the amino acid sequence of SEQ ID NO: 139, 129, 130, 131, 132, 133, 134, 135, 136, 137, or 138, and the light chain comprises the amino acid sequence of SEQ ID NO: 141, 140, or 142; or

[0142] the heavy chain comprises the amino acid sequence of SEQ ID NO: 101, and the light chain comprises the amino acid sequence of SEQ ID NO: 102; or

[0143] the heavy chain comprises the amino acid sequence of SEQ ID NO: 143, and the light chain comprises the amino acid sequence of SEQ ID NO: 141.

[0144] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0145] (1) the heavy chain comprises the amino acid sequence of SEQ ID NO: 78, 76, 77, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 83; or

[0146] the heavy chain comprises the amino acid sequence of SEQ ID NO: 81, 76, 77, 78, 79, or 80, and the light chain comprises the amino acid sequence of SEQ ID NO: 82; or

[0147] the heavy chain comprises the amino acid sequence of SEQ ID NO: 76, 77, 78, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 84; or

[0148] the heavy chain comprises the amino acid sequence of SEQ ID NO: 76, 77, 78, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 85; or

[0149] the heavy chain comprises the amino acid sequence of SEQ ID NO: 76, 77, 78, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 86; or

[0150] the heavy chain comprises the amino acid sequence of SEQ ID NO: 76, 77, 78, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 87; or

[0151] the heavy chain comprises the amino acid sequence of SEQ ID NO: 28, and the light chain comprises the amino acid sequence of SEQ ID NO: 29; or

[0152] the heavy chain comprises the amino acid sequence of SEQ ID NO: 108, and the light chain comprises the amino acid sequence of SEQ ID NO: 83; or

[0153] (2) the heavy chain comprises the amino acid sequence of SEQ ID NO: 55, and the light chain comprises the amino acid sequence of SEQ ID NO: 62; or

[0154] the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 49, 50, 51, 52, 53, 54, 55, or 56, and the light chain comprises the amino acid sequence of SEQ ID NO: 57; or

[0155] the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 49, 50, 51, 52, 53, or 54, and the light chain comprises the amino acid sequence of SEQ ID NO: 58; or

[0156] the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 49, 50, 51, 52, 53, or 54, and the light chain comprises the amino acid sequence of SEQ ID NO: 59; or

[0157] the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 55, or 56, and the light chain comprises the amino acid sequence of SEQ ID NO: 60; or

[0158] the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 55, or 56, and the light chain comprises the amino acid sequence of SEQ ID NO: 61; or

[0159] the heavy chain comprises the amino acid sequence of SEQ ID NO: 26, and the light chain comprises the amino acid sequence of SEQ ID NO: 27; or

[0160] the heavy chain comprises the amino acid sequence of SEQ ID NO: 105, and the light chain comprises the amino acid sequence of SEQ ID NO: 62; or

[0161] (3) the heavy chain comprises the amino acid sequence of SEQ ID NO: 139, and the light chain comprises the amino acid sequence of SEQ ID NO: 141 or 142; or

[0162] the heavy chain comprises the amino acid sequence of SEQ ID NO: 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, or 139, and the light chain comprises the amino acid sequence of SEQ ID NO: 140; or

[0163] the heavy chain comprises the amino acid sequence of SEQ ID NO: 101, and the light chain comprises the amino acid sequence of SEQ ID NO: 102; or

[0164] the heavy chain comprises the amino acid sequence of SEQ ID NO: 143, and the light chain comprises the amino acid sequence of SEQ ID NO: 141.

[0165] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0166] (1) the heavy chain comprises the amino acid sequence of SEQ ID NO: 78 or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 83; or

[0167] the heavy chain comprises the amino acid sequence of SEQ ID NO: 81, 76, or 77, and the light chain comprises the amino acid sequence of SEQ ID NO: 82; or

[0168] the heavy chain comprises the amino acid sequence of SEQ ID NO: 78, and the light chain comprises the amino acid sequence of SEQ ID NO: 84; or

[0169] the heavy chain comprises the amino acid sequence of SEQ ID NO: 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 85; or

[0170] the heavy chain comprises the amino acid sequence of SEQ ID NO: 76, and the light chain comprises the amino acid sequence of SEQ ID NO: 86; or

[0171] the heavy chain comprises the amino acid sequence of SEQ ID NO: 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 87; or

[0172] the heavy chain comprises the amino acid sequence of SEQ ID NO: 28, and the light chain comprises the amino acid sequence of SEQ ID NO: 29; or

[0173] the heavy chain comprises the amino acid sequence of SEQ ID NO: 108, and the light chain comprises the amino acid sequence of SEQ ID NO: 83; or

[0174] (2) the heavy chain comprises the amino acid sequence of SEQ ID NO: 55, and the light chain comprises the amino acid sequence of SEQ ID NO: 62; or

[0175] the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 55, or 56, and the light chain comprises the amino acid sequence of SEQ ID NO: 57; or

[0176] the heavy chain comprises the amino acid sequence of SEQ ID NO: 55, and the light chain comprises the amino acid sequence of SEQ ID NO: 60; or

[0177] the heavy chain comprises the amino acid sequence of SEQ ID NO: 55, and the light chain comprises the amino acid sequence of SEQ ID NO: 61; or

[0178] the heavy chain comprises the amino acid sequence of SEQ ID NO: 26, and the light chain comprises the amino acid sequence of SEQ ID NO: 27; or

[0179] the heavy chain comprises the amino acid sequence of SEQ ID NO: 105, and the light chain comprises the amino acid sequence of SEQ ID NO: 62; or

[0180] (3) the heavy chain comprises the amino acid sequence of SEQ ID NO: 139, and the light chain comprises the amino acid sequence of SEQ ID NO: 141 or 142; or

[0181] the heavy chain comprises the amino acid sequence of SEQ ID NO: 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, or 139, and the light chain comprises the amino acid sequence of SEQ ID NO: 140; or

[0182] the heavy chain comprises the amino acid sequence of SEQ ID NO: 101, and the light chain comprises the amino acid sequence of SEQ ID NO: 102; or

[0183] the heavy chain comprises the amino acid sequence of SEQ ID NO: 143, and the light chain comprises the amino acid sequence of SEQ ID NO: 141.

[0184] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0185] (1) the heavy chain comprises the amino acid sequence of SEQ ID NO: 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 82; or

[0186] (2) the heavy chain comprises the amino acid sequence of SEQ ID NO: 55, and the light chain comprises the amino acid sequence of SEQ ID NO: 62.

[0187] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0188] (1) the heavy chain comprises the amino acid sequence of SEQ ID NO: 78 or 108, and the light chain comprises the amino acid sequence of SEQ ID NO: 83; or

[0189] (2) the heavy chain comprises the amino acid sequence of SEQ ID NO: 55 or 105, and the light chain comprises the amino acid sequence of SEQ ID NO: 62; or

[0190] (3) the heavy chain comprises the amino acid sequence of SEQ ID NO: 139 or 143, and the light chain comprises the amino acid sequence of SEQ ID NO: 141.

[0191] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, wherein:

[0192] (1) the heavy chain comprises the amino acid sequence of SEQ ID NO: 78, and the light chain comprises the amino acid sequence of SEQ ID NO: 83; or

[0193] (2) the heavy chain comprises the amino acid sequence of SEQ ID NO: 55, and the light chain comprises the amino acid sequence of SEQ ID NO: 62.

[0194] (3) the heavy chain comprises the amino acid sequence of SEQ ID NO: 139, and the light chain comprises the amino acid sequence of SEQ ID NO: 141.

[0195] In another aspect, the present disclosure provides a multispecific antibody comprising the anti-B7-H3 antibody of any of the preceding embodiments. In some embodiments, the multispecific antibody is a bispecific antibody.

[0196] <immunoconjugate>

[0197] In another aspect, the present disclosure provides an immunoconjugate comprising a payload, and an anti-B7-H3 antibody of any of the preceding embodiments, or a multispecific antibody of any of the preceding embodiments conjugated to the payload.

[0198] In some embodiments, the immunoconjugate of the preceding embodiment, wherein the payload is selected from the group consisting of a cytotoxic drug, an antineoplastic agent, a polypeptide, an oligonucleotide, an immunomodulatory agent, a biological response modifier, a lectin, a chromophore, a fluorophore, a chemiluminescent compound, an enzyme, a metal ion, and any combination thereof.

[0199] In some embodiments, the immunoconjugate of any of the preceding embodiments, wherein the payload is a cytotoxic drug.

[0200] In some embodiments, the immunoconjugate of any of the preceding embodiments is an antibody drug conjugate.

[0201] In another aspect, the present disclosure provides an antibody drug conjugate comprising an anti-B7-H3 antibody of any of the preceding embodiments, or a multispecific antibody of any of the preceding embodiments.

[0202] In some embodiments, the antibody drug conjugate of the preceding embodiment, wherein the drug is a cytotoxic drug.

[0203] In some embodiments, the antibody drug conjugate of any of the preceding embodiments comprises a structure as follows:

[0204] wherein:

[0205] Y is selected from the group consisting of -O-(CR a R b ) m -CR 1 R 2 -C(O)-, -O-CR 1 R 2 -(CR a R b ) m -, -O-CR1 R 2 -、-NH-(CR a R b ) m -CR 1 R 2 -C(O)- and -S-(CR) a R b ) m -CR 1 R 2 -C(O)-;

[0206] R a and R b They may be the same or different, and each is independently selected from hydrogen atoms, deuterium atoms, halogens, and carbon atoms. 1-6 Alkyl, C 1-6 Haloalkyl, C 1-6 Deuterated alkyl, C 1-6 Alkoxy, hydroxy, amino, cyano, nitro, C 1-6 Hydroxyalkyl, 3- to 6-membered cycloalkyl and 3- to 6-membered heterocyclic groups; or, R a and R b Together with the carbon atoms connected to it, they form 3 to 6-membered cycloalkyl groups or 3 to 6-membered heterocyclic groups;

[0207] R 1 Selected from halogens, C 1-6 Haloalkyl, C 1-6 Deuterated alkyl, 3- to 6-membered cycloalkyl, 3- to 6-membered cycloalkyl C 1-6 Alkyl, C 1-6 Alkoxy C 1-6 Alkyl, 3- to 6-membered heterocyclic, 6- to 10-membered aryl, and 5- to 10-membered heteroaryl; R 2 Selected from hydrogen atoms, halogens, C 1-6 Haloalkyl, C 1-6 Deuterated alkyl, 3- to 6-membered cycloalkyl, 3- to 6-membered cycloalkyl C 1-6 Alkyl, C 1-6 Alkoxy C 1-6 Alkyl, 3- to 6-membered heterocyclic, 6- to 10-membered aryl, and 5- to 10-membered heteroaryl; or, R 1 and R 2 Together with the carbon atoms connected to it, they form 3 to 6-membered cycloalkyl groups or 3 to 6-membered heterocyclic groups;

[0208] Or, R a and R 2 Together with the carbon atom attached thereto, they form 3 to 6-membered cycloalkyl groups or 3 to 6-membered heterocyclic groups;

[0209] m is an integer from 0 to 4;

[0210] n is 1 to 20, n is a decimal or an integer;

[0211] L is a linker unit;

[0212] Ab is an anti-B7-H3 antibody as defined in any of the preceding.

[0213] In some embodiments, the antibody drug conjugate of any of the preceding, wherein:

[0214] Y is -0-(CR a R b ) m -CR 1 R 2 -C(O)-;

[0215] R a and R b are the same or different and each is independently selected from the group consisting of a hydrogen atom, a deuterium atom, a halogen, and C 1-6 alkyl;

[0216] R 1 is C 1-6 haloalkyl or 3- to 6-membered cycloalkyl;

[0217] R 2 is selected from the group consisting of a hydrogen atom, C 1-6 haloalkyl and 3- to 6-membered cycloalkyl;

[0218] Alternatively, R 1 and R 2 together with the carbon atom to which they are attached form a 3- to 6-membered cycloalkyl;

[0219] m is 0 or 1.

[0220] In some embodiments, the antibody drug conjugate of any of the preceding, wherein Y is selected from:

[0221] wherein the O-terminus of Y is attached to the linker unit -L-.

[0222] In some embodiments, the antibody drug conjugate of any of the preceding, wherein the linker unit -L- is -L 1 -L 2 -L 3 -L 4 -,

[0223] L 1 is selected from the group consisting of -(succinimid-3-yl-N)-W-C(O)-, -CH2-C(O)-NR 3 -W-C(O)- and -C(O)-W-C(O)-, wherein W is selected from the group consisting of C 1-8 alkyl, C 1-8alkyl, 3- to 6-membered cycloalkyl and straight-chain heteroalkyl comprising 1 to 3 heteroatoms selected from the group consisting of N, O and S, wherein said C 1-8 alkyl, 3- to 6-membered cycloalkyl and straight-chain heteroalkyl comprising 1 to 3 heteroatoms selected from the group consisting of N, O and S, wherein said C 1-6 alkyl, C 1-6 alkyl, C 1-6 alkyl, C 1-6 alkyl, C 2 one or more substituents selected from the group consisting of halogen, hydroxy, cyano, amino, C

[0224] L 4 (CH2CH2O)pCH2CH2C(O)-, -NR 4 (CH2CH2O)pCH2C(O)-, -S(CH2)pC(O)- and a chemical bond, wherein p is an integer from 1 to 20;

[0225] L 3 is a peptide residue consisting of 2 to 7 amino acid residues, wherein said amino acid residues are selected from the group consisting of amino acid residues formed from phenylalanine, glycine, valine, lysine, citrulline, serine, glutamic acid and aspartic acid, and are optionally further substituted by one or more substituents selected from the group consisting of halogen, hydroxy, cyano, amino, C 1-6 alkyl, C 1-6 alkyl, C 1-6 alkyl, C 1-6 alkyl, C

[0226] L 4 (CH2CH2O)pCH2CH2C(O)-, -NR 5 (CR 6 R 7 ) t -, -C(O)NR 5 -, -C(O)NR 5 (CH2) t - and a chemical bond, wherein t is an integer from 1 to 6;

[0227] R 3 , R 4 and R 5 are identical or different and each independently selected from the group consisting of a hydrogen atom, C 1-6 alkyl, C 1-6 haloalkyl, C 1-6 deuterated alkyl and C 1-6 hydroxyalkyl;

[0228] R 6 and R 7 are identical or different and each independently selected from the group consisting of a hydrogen atom, halogen, C1-6 alkyl, C 1-6 haloalkyl, C 1-6 deuteroalkyl and C 1-6 hydroxyalkyl.

[0229] In some embodiments, the antibody drug conjugate of any of the preceding embodiments, wherein the linker unit -L- is -L 1 -L 2 -L 3 -L 4

[0230] L 1 is s 1 is an integer from 2 to 8;

[0231] L 2 is a chemical bond;

[0232] L 3 is a tetrapeptide residue; preferably, L 3 is a tetrapeptide residue of GGFG;

[0233] L 4 is -NR 5 (CR 6 R 7 )t-, R 5 , R 6 or R 7 are the same or different and each independently a hydrogen atom or C 1-6 alkyl, t is 1 or 2;

[0234] wherein the L 1 end is attached to Ab, and the L 4 end is attached to Y.

[0235] In some embodiments, the antibody drug conjugate of any of the preceding embodiments, wherein -L- is:

[0236] In some embodiments, the antibody drug conjugate of any of the preceding embodiments, comprising a structure as shown below:

[0237] n is 1 to 20, n is a decimal or an integer;

[0238] Ab is an anti-B7-H3 antibody as defined in any of the preceding embodiments.

[0239] ​In some embodiments, the antibody drug conjugate of any of the preceding embodiments, wherein the n is an average number of drug moieties per anti-B7-H3 antibody, can be an integer or a fraction. In some embodiments, the n is 1-20, or 1-10, or 2-10, or 3-10, or 4-10, or 5-10, or 6-10, or 7-10, or 8-10, or 1-9, or 2-9, or 3-9, or 4-9, or 5-9, or 6-9, or 7-9, or 1-8, or 2-8, or 3-8, or 4-8, or 5-8, or 6-8, or 1-7, or 2-7, or 3-7, or 4-7, or 5-7, or 1-6, or 2-6, or 3-6, or 4-6, or 1-5, or 2-5, or 3-5, or 1-4, or 2-4, or 1-3. In some embodiments, the n is about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 11, about 12, about 13, about 14, about 15, about 16, about 17, about 18, about 19, or about 20. In some embodiments, the n is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20.

[0240] In some embodiments, the antibody drug conjugate of any of the preceding embodiments, comprises a structure as shown below:

[0241] wherein:

[0242] n is 1 to 20, preferably 1 to 10, more preferably about 4;

[0243] Ab is an anti-B7-H3 antibody as defined in any of the preceding embodiments, comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises HCDR1, HCDR2, and HCDR3, and the light chain variable region comprises LCDR1, LCDR2, and LCDR3, wherein:

[0244] (1) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 14, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 15, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 16, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 17, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 90, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 19; or

[0245] (2) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 8, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 88, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 89, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 13; or

[0246] (3) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 93, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 144, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 95, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 145, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 146, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 98;

[0247] Preferably,

[0248] (1) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 14, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 15, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 16, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 17, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 18 or 63, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 19; or

[0249] (2) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 8, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 32 or 9, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 30, 11 or 31, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 13; or

[0250] (3) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 93, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 114 or 94, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 95, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 111, 96 or 113, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 112 or 97, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 98;

[0251] More preferably,

[0252] (1) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 14, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 15, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 16, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 17, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 18 or 63, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 19; or

[0253] (2) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 8, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 32, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 30, 11 or 31, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 13; or

[0254] the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 8, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 9, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 11, 30 or 31, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 13; or

[0255] (3) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:93, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 114, and the HCDR3 comprises the amino acid sequence of SEQ ID NO:95, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 111 or 113, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 112, and the LCDR3 comprises the amino acid sequence of SEQ ID NO:98; or

[0256] the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:93, the HCDR2 comprises the amino acid sequence of SEQ ID NO:94 or 114, and the HCDR3 comprises the amino acid sequence of SEQ ID NO:95, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO:96, the LCDR2 comprises the amino acid sequence of SEQ ID NO:97, and the LCDR3 comprises the amino acid sequence of SEQ ID NO:98;

[0257] Most preferably,

[0258] (1) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 14, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 15, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 16, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 17, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 18, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 19; or

[0259] (2) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:8, the HCDR2 comprises the amino acid sequence of SEQ ID NO:32, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO:30, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 13; or

[0260] (3) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 93, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 114, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 95, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 111, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 112, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 98.

[0261] In some embodiments, the antibody drug conjugate of any of the preceding embodiments comprises the structure shown below:

[0262] wherein:

[0263] n is 1 to 20, preferably 1 to 10, more preferably about 4;

[0264] Ab is an anti-B7-H3 antibody as defined in any of the preceding embodiments, wherein:

[0265] (1) the heavy chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 66, 69, 64, 65, 67, or 68, and the light chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 71, 70, 72, 73, 74, or 75; or

[0266] the heavy chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 22, and the light chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 23; or

[0267] (2) the heavy chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 40, 33, 41, 34, 35, 36, 37, 38, or 39, and the light chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 47, 42, 45, 46, 43, or 44; or

[0268] the heavy chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 20, and the light chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 21; or

[0269] (3) the heavy chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 125, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124, and the light chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 127, 126, or 128; or

[0270] the heavy chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 99, and the light chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 100;

[0271] Preferably,

[0272] (1) the heavy chain variable region comprises an amino acid sequence of SEQ ID NO: 66, 69, 64, 65, 67, or 68, and the light chain variable region comprises an amino acid sequence of SEQ ID NO: 71, 70, 72, 73, 74, or 75; or

[0273] the heavy chain variable region comprises an amino acid sequence of SEQ ID NO: 22, and the light chain variable region comprises an amino acid sequence of SEQ ID NO: 23; or

[0274] (2) the heavy chain variable region comprises an amino acid sequence of SEQ ID NO: 40, 33, 41, 34, 35, 36, 37, 38, or 39, and the light chain variable region comprises an amino acid sequence of SEQ ID NO: 47, 42, 45, 46, 43, or 44; or

[0275] the heavy chain variable region comprises an amino acid sequence of SEQ ID NO: 20, and the light chain variable region comprises an amino acid sequence of SEQ ID NO: 21; or

[0276] (3) the heavy chain variable region comprises an amino acid sequence of SEQ ID NO: 125, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124, and the light chain variable region comprises an amino acid sequence of SEQ ID NO: 127, 126, or 128; or

[0277] the heavy chain variable region comprises an amino acid sequence of SEQ ID NO: 99, and the light chain variable region comprises an amino acid sequence of SEQ ID NO: 100;

[0278] More preferably,

[0279] (1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 66, 64, 65, 67, 68, or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 71; or

[0280] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 69, 64, 65, 66, 67, or 68, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 70; or

[0281] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 64, 65, 66, 67, 68, or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 72; or

[0282] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 64, 65, 66, 67, 68, or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 73; or

[0283] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 64, 65, 66, 67, 68, or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 74; or

[0284] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 64, 65, 66, 67, 68, or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 75; or

[0285] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 22, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 23; or

[0286] (2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 47; or

[0287] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 34, 35, 36, 37, 38, 39, 40, or 41, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 42; or

[0288] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 34, 35, 36, 37, 38, or 39, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 43; or

[0289] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 40, or 41, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 45; or

[0290] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 40, or 41, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 45; or

[0291] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 40, or 41, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 45; or

[0292] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 20, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 21; or

[0293] (3) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 125, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 127 or 128; or

[0294] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, or 125, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 126; or

[0295] the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 99, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 100;

[0296] most preferably,

[0297] (1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 66, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 71; or

[0298] (2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 47; or

[0299] (3) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 125, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 127.

[0300] In some embodiments, the antibody drug conjugate of any of the preceding embodiments comprises the structure shown below:

[0301] wherein:

[0302] n is 1 to 20, preferably 1 to 10, more preferably about 4;

[0303] Ab is an anti-B7-H3 antibody as defined in any of the preceding, wherein the anti-B7-H3 antibody comprises a heavy chain and a light chain, wherein:

[0304] (1) the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 78, 81, 76, 77, 79, or 80, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 83, 82, 84, 85, 86, or 87; or

[0305] the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 28, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 29; or

[0306] the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 108, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 83; or

[0307] (2) the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 55, 48, 49, 50, 51, 52, 53, 54, or 56, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 62, 57, 58, 59, 60, or 61; or

[0308] the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 26, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 27; or

[0309] the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 105, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 62; or

[0310] (3) the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 139, 129, 130, 131, 132, 133, 134, 135, 136, 137, or 138, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 141, 140, or 142; or

[0311] the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 101, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 102; or

[0312] the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 143, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 141;

[0313] Preferably,

[0314] (1) the heavy chain comprises the amino acid sequence of SEQ ID NO: 78, 81, 76, 77, 79, or 80, and the light chain comprises the amino acid sequence of SEQ ID NO: 83, 82, 84, 85, 86, or 87; or

[0315] the heavy chain comprises the amino acid sequence of SEQ ID NO: 28, and the light chain comprises the amino acid sequence of SEQ ID NO: 29; or

[0316] the heavy chain comprises the amino acid sequence of SEQ ID NO: 108, and the light chain comprises the amino acid sequence of SEQ ID NO: 83; or

[0317] (2) the heavy chain comprises the amino acid sequence of SEQ ID NO: 55, 48, 49, 50, 51, 52, 53, 54, or 56, and the light chain comprises the amino acid sequence of SEQ ID NO: 62, 57, 58, 59, 60, or 61; or

[0318] the heavy chain comprises the amino acid sequence of SEQ ID NO: 26, and the light chain comprises the amino acid sequence of SEQ ID NO: 27; or

[0319] the heavy chain comprises the amino acid sequence of SEQ ID NO: 105, and the light chain comprises the amino acid sequence of SEQ ID NO: 62; or

[0320] (3) the heavy chain comprises the amino acid sequence of SEQ ID NO: 139, 129, 130, 131, 132, 133, 134, 135, 136, 137, or 138, and the light chain comprises the amino acid sequence of SEQ ID NO: 141, 140, or 142; or

[0321] the heavy chain comprises the amino acid sequence of SEQ ID NO: 101, and the light chain comprises the amino acid sequence of SEQ ID NO: 102; or

[0322] the heavy chain comprises the amino acid sequence of SEQ ID NO: 143, and the light chain comprises the amino acid sequence of SEQ ID NO: 141;

[0323] More preferably,

[0324] (1) the heavy chain comprises the amino acid sequence of SEQ ID NO: 78, 76, 77, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 83; or

[0325] the heavy chain comprises the amino acid sequence of SEQ ID NO: 81, 76, 77, 78, 79, or 80, and the light chain comprises the amino acid sequence of SEQ ID NO: 82; or

[0326] the heavy chain comprises the amino acid sequence of SEQ ID NO: 76, 77, 78, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 84; or

[0327] the heavy chain comprises the amino acid sequence of SEQ ID NO: 76, 77, 78, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 85; or

[0328] the heavy chain comprises the amino acid sequence of SEQ ID NO: 76, 77, 78, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 86; or

[0329] the heavy chain comprises the amino acid sequence of SEQ ID NO: 76, 77, 78, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 87; or

[0330] the heavy chain comprises the amino acid sequence of SEQ ID NO: 28, and the light chain comprises the amino acid sequence of SEQ ID NO: 29; or

[0331] the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 49, 50, 51, 52, 53, 54, 55, or 56, and the light chain comprises the amino acid sequence of SEQ ID NO: 57; or

[0332] (2) the heavy chain comprises the amino acid sequence of SEQ ID NO: 55, and the light chain comprises the amino acid sequence of SEQ ID NO: 62; or

[0333] the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 49, 50, 51, 52, 53, 54, 55, or 56, and the light chain comprises the amino acid sequence of SEQ ID NO: 57; or

[0334] the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 49, 50, 51, 52, 53, or 54, and the light chain comprises the amino acid sequence of SEQ ID NO: 58; or

[0335] the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 49, 50, 51, 52, 53, or 54, and the light chain comprises the amino acid sequence of SEQ ID NO: 59; or

[0336] the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 55, or 56, and the light chain comprises the amino acid sequence of SEQ ID NO: 60; or

[0337] the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 55, or 56, and the light chain comprises the amino acid sequence of SEQ ID NO: 61; or

[0338] the heavy chain comprises the amino acid sequence of SEQ ID NO: 26, and the light chain comprises the amino acid sequence of SEQ ID NO: 27; or

[0339] the heavy chain comprises the amino acid sequence of SEQ ID NO: 105, and the light chain comprises the amino acid sequence of SEQ ID NO: 62; or

[0340] (3) the heavy chain comprises the amino acid sequence of SEQ ID NO: 139, and the light chain comprises the amino acid sequence of SEQ ID NO: 141 or 142; or

[0341] the heavy chain comprises the amino acid sequence of SEQ ID NO: 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, or 139, and the light chain comprises the amino acid sequence of SEQ ID NO: 140; or

[0342] the heavy chain comprises the amino acid sequence of SEQ ID NO: 101, and the light chain comprises the amino acid sequence of SEQ ID NO: 102; or

[0343] the heavy chain comprises the amino acid sequence of SEQ ID NO: 143, and the light chain comprises the amino acid sequence of SEQ ID NO: 141;

[0344] more preferably,

[0345] (1) the heavy chain comprises the amino acid sequence of SEQ ID NO: 108 or 78, and the light chain comprises the amino acid sequence of SEQ ID NO: 83; or

[0346] (2) the heavy chain comprises the amino acid sequence of SEQ ID NO: 105 or 55, and the light chain comprises the amino acid sequence of SEQ ID NO: 62; or

[0347] (3) the heavy chain comprises the amino acid sequence of SEQ ID NO: 143 or 139, and the light chain comprises the amino acid sequence of SEQ ID NO: 141;

[0348] most preferably,

[0349] (1) the heavy chain comprises the amino acid sequence of SEQ ID NO: 108, and the light chain comprises the amino acid sequence of SEQ ID NO: 83; or

[0350] (2) the heavy chain comprises the amino acid sequence of SEQ ID NO: 105, and the light chain comprises the amino acid sequence of SEQ ID NO: 62; or

[0351] (3) the heavy chain comprises the amino acid sequence of SEQ ID NO: 143, and the light chain comprises the amino acid sequence of SEQ ID NO: 141.

[0352] In another aspect, the present disclosure provides an anti-B7-H3 antibody that competes for binding to human B7-H3 with an anti-B7-H3 antibody as described in any of the preceding aspects, or a multispecific antibody as described in any of the preceding aspects, or an immunoconjugate as described in any of the preceding aspects, or an antibody drug conjugate as described in any of the preceding aspects.

[0353] In another aspect, the present disclosure provides an anti-B7-H3 antibody that binds to the same human B7-H3 antigenic epitope as an anti-B7-H3 antibody as described in any of the preceding aspects, or a multispecific antibody as described in any of the preceding aspects, or an immunoconjugate as described in any of the preceding aspects, or an antibody drug conjugate as described in any of the preceding aspects.

[0354] In another aspect, the present disclosure provides a pharmaceutical composition comprising the anti-B7-H3 antibody of any of the preceding aspects, or the multispecific antibody of any of the preceding aspects, or the immunoconjugate of any of the preceding aspects, or the antibody drug conjugate of any of the preceding aspects, and one or more pharmaceutically acceptable carriers, diluents, or excipients.

[0355] In another aspect, the present disclosure provides an anti-B7-H3 antibody that competes for binding to human B7-H3 with the anti-B7-H3 antibody of any of the preceding aspects, or the multispecific antibody of any of the preceding aspects, or the immunoconjugate of any of the preceding aspects.

[0356] In another aspect, the present disclosure provides an anti-B7-H3 antibody that binds to the same human B7-H3 epitope as the anti-B7-H3 antibody of any of the preceding aspects, or the multispecific antibody of any of the preceding aspects, or the immunoconjugate of any of the preceding aspects.

[0357] In another aspect, the present disclosure provides a pharmaceutical composition comprising the anti-B7-H3 antibody of any of the preceding aspects, or the multispecific antibody of any of the preceding aspects, or the immunoconjugate of any of the preceding aspects, and one or more pharmaceutically acceptable carriers, diluents, or excipients.

[0358] In some embodiments, the pharmaceutical composition contains 0.01-99.99% of the anti-B7-H3 antibody of any of the preceding aspects, or the multispecific antibody of any of the preceding aspects, or the immunoconjugate of any of the preceding aspects, or the antibody drug conjugate of any of the preceding aspects, based on the total weight of the composition. In some embodiments, the pharmaceutical composition contains 0.1-99.9% of the anti-B7-H3 antibody of any of the preceding aspects, or the multispecific antibody of any of the preceding aspects, or the immunoconjugate of any of the preceding aspects, or the antibody drug conjugate of any of the preceding aspects. In some embodiments, the pharmaceutical composition contains 0.5%-99.5% of the anti-B7-H3 antibody of any of the preceding aspects, or the multispecific antibody of any of the preceding aspects, or the immunoconjugate of any of the preceding aspects, or the antibody drug conjugate of any of the preceding aspects. In some embodiments, the pharmaceutical composition contains 1%-99% of the anti-B7-H3 antibody of any of the preceding aspects, or the multispecific antibody of any of the preceding aspects, or the immunoconjugate of any of the preceding aspects, or the antibody drug conjugate of any of the preceding aspects. In some embodiments, the pharmaceutical composition contains 2%-98% of the anti-B7-H3 antibody of any of the preceding aspects, or the multispecific antibody of any of the preceding aspects, or the immunoconjugate of any of the preceding aspects, or the antibody drug conjugate of any of the preceding aspects.

[0359] In some embodiments, the pharmaceutical composition contains 0.01-99.99% of a pharmaceutically acceptable carrier, diluent, or excipient, based on the total weight of the composition. In some embodiments, the pharmaceutical composition contains 0.1-99.9% of a pharmaceutically acceptable carrier, diluent, or excipient. In some embodiments, the pharmaceutical composition contains 0.5-99.5% of a pharmaceutically acceptable carrier, diluent, or excipient. In some embodiments, the pharmaceutical composition contains 1-99% of a pharmaceutically acceptable carrier, diluent, or excipient. In some embodiments, the pharmaceutical composition contains 2-98% of a pharmaceutically acceptable carrier, diluent, or excipient.

[0360] In another aspect, the present disclosure provides an isolated nucleic acid encoding the anti-B7-H3 antibody of any of the preceding, or the multispecific antibody of any of the preceding.

[0361] In another aspect, the present disclosure provides a vector comprising the isolated nucleic acid of the preceding.

[0362] In another aspect, the present disclosure provides a host cell comprising the isolated nucleic acid of the preceding, or the vector of the preceding.

[0363] In another aspect, the present disclosure provides a method for producing the anti-B7-H3 antibody of any of the preceding, or the multispecific antibody of any of the preceding, the method comprising the steps of culturing the host cell of the preceding in a culture medium to form and accumulate the anti-B7-H3 antibody of any of the preceding, or the multispecific antibody of any of the preceding, and recovering the antibody from the culture.

[0364] In another aspect, the present disclosure provides use of the anti-B7-H3 antibody of any of the preceding, or the multispecific antibody of any of the preceding, or the immunoconjugate of any of the preceding, or the antibody drug conjugate of any of the preceding, or the pharmaceutical composition of the preceding, in the manufacture of a medicament for treating or preventing a disease or disorder.

[0365] In another aspect, the present disclosure provides a method of treating or preventing a disease or disorder, the method comprising administering to a subject a therapeutically or prophylactically effective amount of the anti-B7-H3 antibody of any of the preceding, or the multispecific antibody of any of the preceding, or the immunoconjugate of any of the preceding, or the antibody drug conjugate of any of the preceding, or the pharmaceutical composition of the preceding.

[0366] In another aspect, the present disclosure provides an anti-B7-H3 antibody as described in any of the preceding, or a multispecific antibody as described in any of the preceding, or an immunoconjugate as described in any of the preceding, or an antibody drug conjugate as described in any of the preceding, or a pharmaceutical composition as described in any of the preceding, for use as a medicament. In some embodiments, the medicament is for treating or preventing a disease or disorder.

[0367] In another aspect, the present disclosure provides use of an anti-B7-H3 antibody as described in any of the preceding, or a multispecific antibody as described in any of the preceding, or an immunoconjugate as described in any of the preceding, or a pharmaceutical composition as described in any of the preceding, in the manufacture of a medicament for treating or preventing a disease or disorder.

[0368] In another aspect, the present disclosure provides a method of treating or preventing a disease or disorder, the method comprising administering to a subject a therapeutically or prophylactically effective amount of an anti-B7-H3 antibody as described in any of the preceding, or a multispecific antibody as described in any of the preceding, or an immunoconjugate as described in any of the preceding, or a pharmaceutical composition as described in any of the preceding.

[0369] In another aspect, the present disclosure provides an anti-B7-H3 antibody as described in any of the preceding, or a multispecific antibody as described in any of the preceding, or an immunoconjugate as described in any of the preceding, or a pharmaceutical composition as described in any of the preceding, for use as a medicament. In some embodiments, the medicament is for treating or preventing a disease or disorder.

[0370] In some embodiments, the disease or disorder as described in any of the preceding is a tumor.

[0371] In some embodiments, the disease or disorder as described in any of the preceding is a solid tumor or a hematological tumor.

[0372] In some embodiments, the disease or disorder as described in any of the preceding is neuroblastoma, lung cancer, breast cancer, ovarian cancer, prostate cancer, esophageal cancer, pancreatic cancer, endometrial cancer, gastric cancer, melanoma, liver cancer, colorectal cancer, central nervous system cancer, glioma, glioblastoma, glioblastoma multiforme, head and neck cancer, squamous cell carcinoma, sarcoma, brain cancer, nasopharyngeal cancer, renal cancer, endometrial cancer, or bladder cancer.

[0373] In some embodiments, the disease or disorder as described in any of the preceding is neuroblastoma or lung cancer.

[0374] In some embodiments, the disease or disorder as described in any of the preceding is neuroblastoma.

[0375] In some embodiments, the disease or disorder as described in any of the preceding is associated with B7-H3.

[0376] In some embodiments, the anti-B7-H3 antibodies provided herein bind to NCI-H358 cells with an EC50value of less than 10 nM (e.g., less than 5 nM, less than 4 nM, less than 3 nM, less than 2 nM, less than 1 nM, less than 0.5 nM, less than 0.1 nM, less than 0.05 nM, less than 0.01 nM), as measured by FACS. 50 In some embodiments, the anti-B7-H3 antibodies provided herein bind to NCI-H358 cells with an EC50value of less than 10 nM (e.g., less than 5 nM, less than 4 nM, less than 3 nM, less than 2 nM, less than 1 nM, less than 0.5 nM, less than 0.1 nM, less than 0.05 nM, less than 0.01 nM), as measured by FACS. 50 In some embodiments, the anti-B7-H3 antibodies provided herein bind to NCI-H358 cells with an EC50value of less than 10 nM (e.g., less than 5 nM, less than 4 nM, less than 3 nM, less than 2 nM, less than 1 nM, less than 0.5 nM, less than 0.1 nM, less than 0.05 nM, less than 0.01 nM), as measured by FACS.

[0377] In some embodiments, the anti-B7-H3 antibodies provided herein bind to NCI-H358 cells with an EC50value of less than 10 nM (e.g., less than 5 nM, less than 4 nM, less than 3 nM, less than 2 nM, less than 1 nM, less than 0.5 nM, less than 0.1 nM, less than 0.05 nM, less than 0.01 nM), as measured by FACS. 50 In some embodiments, the anti-B7-H3 antibodies provided herein bind to NCI-H358 cells with an EC50value of less than 10 nM (e.g., less than 5 nM, less than 4 nM, less than 3 nM, less than 2 nM, less than 1 nM, less than 0.5 nM, less than 0.1 nM, less than 0.05 nM, less than 0.01 nM), as measured by FACS. 50 In some embodiments, the anti-B7-H3 antibodies provided herein bind to NCI-H358 cells with an EC50value of less than 10 nM (e.g., less than 5 nM, less than 4 nM, less than 3 nM, less than 2 nM, less than 1 nM, less than 0.5 nM, less than 0.1 nM, less than 0.05 nM, less than 0.01 nM), as measured by FACS.

[0378] In some embodiments, the anti-B7-H3 antibodies provided herein bind to human B7-H3-4lg with a KDvalue of less than 1E-07 M (e.g., less than 5E-08 M, less than 1E-08 M, less than 5E-09 M, less than 1E-09 M, less than 5E-10 M, less than 1E-10 M, less than 5E-11 M, less than 1E-11 M), as measured by Biacore.

[0379] In some embodiments, the anti-B7-H3 antibodies provided herein have better endocytosis activity than a control antibody (e.g., Ab1).

[0380] In some embodiments, the anti-B7-H3 antibody drug conjugates provided herein have better in vitro cell killing activity. BRIEF DESCRIPTION OF DRAWINGS

[0381] Figure 1A: Binding activity of humanized antibodies of Test Example 1, Experiment 1, to NCI-H358 cells.

[0382] Figure 1B: Binding activity of humanized antibodies and negative control antibody of Test Example 1, Experiment 2, to NCI-H358 cells.

[0383] Figure 1C: Binding activity of humanized antibodies of Test Example 1, Experiment 3, to NCI-H358 cells.

[0384] Figure 2A: Binding activity of humanized antibodies of Test Example 2, Experiment 1, to NCI-H358 cells.

[0385] Figure 2B: Binding activity of humanized antibodies of Test Example 2, Experiment 2, to NCI-H358 cells.

[0386] Figure 3A: Endocytosis activity of humanized antibodies of Test Example 4 and positive control antibody, negative control antibody in NCI-H358 cells.

[0387] Figure 3B: Endocytosis activity of humanized antibodies of Test Example 4 and positive control antibody, negative control antibody in NCI-H358 cells. DETAILED DESCRIPTION

[0388] TERMINOLOGY

[0389] For the purposes of the present disclosure, certain technical and scientific terms are described below. Unless specifically defined herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0390] As used in the specification and claims, the singular forms "a," "an" and "the" include plural references unless the context clearly dictates otherwise.

[0391] Unless the context clearly indicates otherwise, throughout the patent specification and claims, the words "comprise", "have" and "include" and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense that receives limitation. Unless the context clearly indicates otherwise, throughout the patent specification and claims, the words "comprise", "have" and "include" and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense that receives limitation.

[0392] The term "and / or", means both "and" and "or". For example, the phrase "A, B and / or C" is intended to cover the following aspects: A, B and C; A, B or C; A or C; A or B; B or C; A and C; A and B; B and C; A (alone); B (alone); and C (alone).

[0393] The terms "B7-H3", "B7H3" and "CD276" are used interchangeably and include variants, isoforms, homologs, orthologs and paralogs of B7-H3. In humans, B7-H3 exists in both a 4Ig domain form (B7-H3-4Ig) and a 2Ig domain form (B7-H3-2Ig). Human B7-H3-4Ig has the amino acid sequence of Uniprot: Q5ZPR3-1. Human B7-H3-2Ig has the amino acid sequence of Uniprot: Q5ZPR3-2. Macaca fascicularis B7-H3-4Ig has the amino acid sequence of NCBI: XP_015308534.1. Mouse B7-H3-2Ig has the amino acid sequence of NCBI: NP_598744.1. Although specific database accession numbers are given, one of skill in the art understands that the B7-H3 referred to herein encompasses corresponding sequences reported in other databases or literature.

[0394] The three letter code and one letter code for amino acids used herein are as described in J. Biol. Chem, 243, p 3558 (1968).

[0395] The term "amino acid" refers to naturally occurring and synthetic amino acids, as well as amino acid analogs and amino acid mimetics that function in a manner similar to the naturally occurring amino acids. Naturally occurring amino acids are those encoded by the genetic code, such as the twenty amino acids normally found in proteins. Amino acid analogs refer to compounds that have the same basic chemical structure (i.e., an alpha carbon bonded to a hydrogen, a carboxyl, an amino, and an R group) as a naturally occurring amino acid, such as homoserine, norleucine, methionine sulfoxide, methionine methylsulfonium. Such analogs have modified R groups (e.g., norleucine) or modified peptide backbones, but otherwise function in a manner similar to naturally occurring amino acids. Amino acid mimetics refer to chemical compounds that have a structure that is different from the general chemical structure of an amino acid, but that functions in a manner similar to a naturally occurring amino acid.

[0396] The term "amino acid mutation" includes amino acid substitutions (also termed amino acid replacements), deletions, insertions, and modifications. Any combination of substitution, deletion and insertion and modification can be made to arrive at the final construct, as long as the final construct possesses the desired properties, such as reduced or no binding to an Fc receptor. Amino acid sequence deletions and insertions include deletions and insertions at the amino- and / or carboxy-terminus of a polypeptide chain. A particular amino acid mutation can be an amino acid substitution. In some embodiments, the amino acid mutation is a non-conservative amino acid substitution, i.e., the substitution of one amino acid for another with different structural and / or chemical properties. Amino acid substitutions include substitutions by non-naturally occurring amino acids or by derivatives of the 20 natural amino acids (e.g., 4-hydroxyproline, 3-methylhistidine, ornithine, homoserine, 5- hydroxylysine). Genetic or chemical methods known in the art can be used to generate amino acid mutations. Genetic methods can include site-directed mutagenesis, PCR, gene synthesis, and the like. Methods other than genetic engineering to alter the side chain groups of amino acids, such as chemical modifications, are also expected to be useful. Various names can be used herein to refer to the same amino acid mutation. In this regard, the amino acid residue at a particular position can be denoted in the position + amino acid residue format, e.g., 234A, to indicate that the amino acid residue at position 234 is A. L234A indicates that the amino acid residue at position 234 is mutated from L to A. It is understood that when an amino acid sequence is defined in the claims in the position + residue format, the amino acid prior to mutation at that position does not limit the claims.

[0397] The terms "polypeptide" and "protein" are used interchangeably herein to refer to a polymer of amino acid residues. The term applies to amino acid polymers in which one or more amino acid residues are artificial chemical mimics of corresponding naturally occurring amino acids, as well as to naturally occurring amino acid polymers and non-naturally occurring amino acid polymers. Unless otherwise indicated, a particular polypeptide sequence implicitly includes conservatively modified variants thereof.

[0398] The term "antibody" is used in the broadest sense, and encompasses various antibody structures, including but not limited to monoclonal antibodies, polyclonal antibodies; monospecific antibodies, multispecific antibodies (e.g., bispecific antibodies), full-length antibodies and antibody fragments (or antigen binding fragments, or antigen binding portions), so long as they exhibit the desired antigen-binding activity.

[0399] The term "antigen binding fragment" encompasses full-length antibodies, Fabs, modified Fabs, Fab', Fab'-SH, modified Fab', F(ab')2, Fv, dsFv, Fab-Fv, Fab-dsFv, Fd, single domain antibodies (sdAbs, e.g., VH or VL or VHH), single chain Fabs (scFabs), single chain antibodies (e.g., scFv, sc(Fv)2), diabodies, linear antibodies, bi- or tri- or tetra-valent antibodies, Bis-scFv, diabody, tribody, triabody, tetrabody, and epitope binding fragments of any of the above. Methods of generating and making these antigen binding fragments are well known in the art.

[0400] A "native antibody" refers to an immunoglobulin molecule naturally occurring. For example, a native IgG antibody is a heterotetrameric glycoprotein of about 150000 daltons, composed of two light chains and two heavy chains that are disulfide-bonded. From N- to C-terminus, each heavy chain has a variable region (VH), also called a variable heavy domain, a heavy chain variable region, followed by three constant domains (CH1, CH2, and CH3). Similarly, from N- to C-terminus, each light chain has a variable region (VL), also called a variable light domain, or light chain variable domain, followed by a constant light domain (CL).

[0401] The terms "full-length antibody," "intact antibody," and "whole antibody" are used herein interchangeably to refer to an antibody with a structure substantially similar to a native antibody structure or a heavy chain having an Fc region as defined herein. A native intact antibody light chain includes a light chain variable region, VL, at the amino terminus of the light chain, and a constant region, CL, including kappa and lambda chains; a heavy chain includes a variable region, VH, at the amino terminus of the heavy chain, and a constant region at the carboxy terminus, wherein CH3 is closest to the carboxy terminus of the polypeptide, the heavy chain can be of any isotype, including IgG (including IgGl, IgG2, IgG3, and IgG4 subtypes), IgA (including IgAl and IgA2 subtypes), IgM, and IgE.

[0402] The term "Fc region" or "fragment, crystallizable region" is used to define a C-terminal region of an antibody heavy chain, including native and engineered Fc regions. In some embodiments, the Fc region comprises two subunits, which can be identical or different. Suitable Fc regions for use in the antibodies described herein include Fc regions of human IgGl, IgG2 (IgG2A, IgG2B), IgG3, and IgG4. In some embodiments, the boundaries of the Fc region can also vary, for example, the C-terminal lysine (residue 447 according to EU numbering system) of the Fc region can be absent, or the C-terminal glycine and lysine (residue 446 and 447 according to EU numbering system) of the Fc region can be absent. Unless otherwise specified, numbering of the Fc region is according to the EU numbering system, also referred to as the EU index.

[0403] The Fc region can be suitably obtained by partially digesting an IgG monoclonal antibody or the like with a proteolytic enzyme such as pepsin, followed by eluting the fraction adsorbed to a protein A or protein G column. As the proteolytic enzyme, an enzyme that can digest a full-length antibody in a limited manner to produce Fab, F(ab')2, by suitably setting the reaction conditions of the enzyme such as pH, is used without particular limitation, and for example, pepsin, papain, or the like can be exemplified.

[0404] The term "variable region" or "variable domain" of an antibody refers to the domain of an antibody heavy or light chain that is involved in binding the antibody to an antigen. In this document, the variable domains of a human antibody heavy chain (VH) and light chain (VL) each comprise four conserved framework regions (FRs) and three complementarity determining regions (CDRs). Within the variable domains, the term "complementarity determining region" or "CDR" refers to a region that is primarily responsible for binding to an antigen; the "framework" or "FR" refers to the variable domain residues other than the CDR residues. The VH contains three CDR regions: HCDR1, HCDR2, and HCDR3; the VL contains three CDR regions: LCDR1, LCDR2, and LCDR3. Each of the VH and VL is composed of three CDRs and four FRs, arranged from amino-terminus (also referred to as N-terminus) to carboxy-terminus (also referred to as C-terminus) in the following order: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4.

[0405] The boundaries of the CDRs can be determined by various known schemes, such as the "Kabat" numbering convention, the "Chothia" numbering convention, the "ABM" numbering convention, the "contact" numbering convention, and the ImMunoGenTics (IMGT) numbering convention, etc.; the correspondence between the various numbering systems is well known to those skilled in the art, and exemplary is shown in Table A below.

[0406] Table A. Relationship between CDR numbering systems

[0407] Unless otherwise specified, the variable regions and CDRs in the embodiments of the present disclosure are in accordance with the "Kabat" numbering convention.

[0408] The term "antibody fragment" refers to a molecule other than an intact antibody that comprises a portion of an intact antibody that binds to an antigen bound by the intact antibody. Examples of antibody fragments include but are not limited to Fv, dsFv, Fab, Fab', Fab'-SH, Fd, F(ab')2, single-domain antibody (sdAb, e.g., VH, VL, or VHH), single-chain Fab (scFab, sc(Fv)2), diabody, linear antibody, single-chain antibody (e.g., scFv); and multispecific antibody formed from antibody fragments.

[0409] The term "chimeric" antibody refers to an antibody in which a portion of the heavy and / or light chain is derived from a particular source or species, while the remaining portion of the heavy and / or light chain is derived from a different, different source or species.

[0410] The term "humanized" antibody is an antibody that retains the reactivity of a non-human antibody while having lower immunogenicity in humans. For example, this can be achieved by retaining the non-human CDR regions and replacing the remainder of the antibody with its human counterpart (i.e., the constant region as well as the framework region portion of the variable region).

[0411] The terms "human antibody", "human-derived antibody", "fully human antibody", "fully human antibody" are used interchangeably and mean an antibody in which the variable and constant regions are of human sequence. The term encompasses antibodies derived from human genes but which have been altered, e.g., to reduce possible immunogenicity, to increase affinity, to eliminate cysteines or glycosylation sites that can cause undesirable folding, etc. The term encompasses these antibodies that are recombinantly produced in non-human cells, which can impart non-human cell-like glycosylation. The term also encompasses antibodies that have been produced in transgenic mice containing some or all human immunoglobulin heavy and light chain loci. The definition of a human antibody expressly excludes humanized antibodies.

[0412] The term "affinity" refers to the overall strength of the noncovalent interactions between individual binding sites of a molecule (e.g., an antibody) and its binding partner (e.g., an antigen). Unless otherwise indicated, as used herein, binding "affinity" refers to intrinsic binding affinity, which reflects the 1 : 1 interaction between members of a binding pair (e.g., antibody and antigen). The affinity of a molecule X for its ligand Y can be generally represented by the dissociation constant (KD). Affinity can be measured by routine methods known in the art, including those described herein.

[0413] The term "kassoc" or "ka", as used herein, refers to the association rate of a particular antibody-antigen interaction. The term "kdis" or "kd", as used herein, refers to the dissociation rate of a particular antibody-antigen interaction. The term "KD" refers to the dissociation constant, which is obtained from the ratio of kd to ka (i.e., kd / ka) and is expressed as a molar concentration (M). KDvalues for antibodies can be determined using methods well known in the art. For example, affinity in solution can be measured using a biosensor system, such as a Biacore system (e.g., BIAcore), or by a solution equilibrium titration method (SET).

[0414] The term "surface plasmon resonance" refers to an optical phenomenon that detects alterations in protein concentrations within a biosensor matrix in real-time, for example, using a BIAcore system (Biacore LifeSciences division of GE Healthcare, Piscataway, NJ).

[0415] The term "effector function" refers to those biological activities attributable to an antibody Fc region (a native sequence Fc region or an Fc region mutated at amino acid sequences) and which vary with the antibody isotype. Examples of antibody effector functions include but are not limited to: Clq binding and complement dependent cytotoxicity, Fc receptor binding, antibody-dependent cell-mediated cytotoxicity (ADCC), phagocytosis, down regulation of cell surface receptors (e.g., B cell receptor), and B cell activation.

[0416] The term "monoclonal antibody" refers to a population of substantially homogeneous antibodies, i.e., the antibody molecules comprising the population are identical in am ino acid sequence except for possible naturally occurring mutations that can be present in minor amounts. In contrast, polyclonal antibodies typically include a population of different antibodies which can differ in their variable domain amino acid sequences, which are typically specific for different epitopes.

[0417] The term "bispecific antibody" refers to an antibody (including an antibody or antigen binding fragment thereof, such as a single chain antibody) that is capable of specifically binding to two different antigens or at least two different epitopes of the same antigen. Various structures of bispecific antibodies have been disclosed in the prior art, which can be divided into IgG-like bispecific antibodies and antibody fragment type bispecific antibodies according to the integrity of IgG molecules, which can be divided into divalent, trivalent, tetravalent or more valent bispecific antibodies according to the number of antigen binding regions, and which can be divided into symmetric structure bispecific antibodies and asymmetric structure bispecific antibodies according to whether the structure is symmetric. Among them, the bispecific antibody based on antibody fragments, such as Fab fragments lacking Fc fragments, which forms a bispecific antibody by combining 2 or more Fab fragments in one molecule, has lower immunogenicity, and has smaller molecular weight, higher tumor tissue penetration; IgG-like bispecific antibodies (such as those with Fc fragments), such antibodies have relatively large molecular weight, and the Fc fragment helps to purify the antibody and improves its solubility, stability, and the Fc part can also bind to the receptor FcRn to increase the serum half-life of the antibody.

[0418] The term "antigen" refers to a molecule or a portion of a molecule capable of being selectively bound by, for example, an antigen binding protein (including, e.g., an antibody). An antigen can have one or more epitopes capable of interacting with different antigen binding proteins (e.g., antibodies).

[0419] The term "epitope" refers to a region (area or region) on an antigen to which an antibody or antigen binding fragment thereof specifically binds. An epitope can be formed by contiguous amino acids (linear epitopes) or comprise non-contiguous amino acids (conformational epitopes) that come into spatial proximity due to folding of the antigen. The difference between conformational and linear epitopes is that binding of an antibody to a conformational epitope is lost in the presence of a denaturing solvent. An epitope comprises at least 3, at least 4, at least 5, at least 6, at least 7, or 8-10 amino acids in a unique spatial conformation. Screening for antibodies that bind to a particular epitope (i.e., those that bind to the same epitope) can be performed using routine methods in the art, such as, but not limited to, alanine scanning, peptide mapping, peptide cleavage analysis, epitope excision, epitope extraction, chemical modification of the antigen (see Prot. Sci. 9 (2000) 487-496), and cross-blocking.

[0420] The terms "capable of specifically binding," "specifically binding," or "bind" mean that an antibody is capable of binding to a certain antigen or epitope with higher affinity than to other antigens or epitopes. Typically, an antibody binds to an antigen or epitope with an equilibrium dissociation constant (KD) of about 1 x 10 -6 M or less (e.g., about 1 x 10 -7 M, 1 x 10 -8 M, 1 x 10 -9 M, 1 x 10 -10 M, 1 x 10 -11 M or less). In some embodiments, the KD of an antibody binding to an antigen is 10% or less (e.g., 1%) of the KD of the antibody binding to a non-specific antigen (e.g., BSA, casein). KD can be measured using known methods, e.g., by surface plasmon resonance assays. However, an antibody that specifically binds to an antigen or epitope does not exclude cross-reactivity to other related antigens, e.g., cross-reactivity to the corresponding antigen from other species (homologs), such as human or monkey, e.g., Macaca fascicularis (cynomolgus, cyno), Pan troglodytes (chimpanzee, chimp), or Callithrix jacchus (common marmoset, marmoset).

[0421] The terms "antibody-dependent cellular cytotoxicity," "antibody-dependent cell-mediated cytotoxicity," or "ADCC" is a mechanism of inducing cell death that relies on the interaction of antibody-coated target cells with effector cells having lytic activity, such as natural killer cells (NK), monocytes, macrophages, and neutrophils, via Fcy receptors (FcyRs) expressed on the effector cells. For example, NK cells express FcyRIIIa, while monocytes express FcyRI, FcyRII, and FcyRIIIa. The ADCC activity of the antibodies provided herein can be assessed using an in vitro assay using cells expressing an antigen as target cells and NK cells as effector cells. Cell lysis is detected based on the release of a label (e.g., a radioactive substrate, a fluorescent dye, or a native intracellular protein) from the lysed cells.

[0422] The term "antibody-dependent cellular phagocytosis (ADCP)" refers to a mechanism of eliminating antibody-coated target cells by internalization by phagocytic cells, such as macrophages or dendritic cells.

[0423] ​The term "complement-dependent cytotoxicity" or "CDC" refers to a mechanism of inducing cell death in which the Fc effector domain of a target-bound antibody binds and activates complement component Clq, which in turn activates the complement cascade, leading to target cell death. Activation of complement can also result in the deposition of complement components on the surface of target cells, which promote CDC by binding to complement receptors (e.g., CR3) on leukocytes.

[0424] The term "nucleic acid" is used interchangeably herein with the term "polynucleotide" and refers to deoxyribonucleotides or ribonucleotides and polymers thereof in either single- or double-stranded form. The term encompasses nucleic acids containing known nucleotide analogs or modified backbone residues or linkages, which are synthetic, naturally occurring, and non-naturally occurring, which have similar binding properties to the reference nucleotide, and which are metabolized in a manner similar to the reference nucleotides. Examples of such analogs include, without limitation, phosphorothioates, phosphoramidates, methyl phosphonates, chiral-methyl phosphonates, 2-O-methyl ribonucleotides, peptide-nucleic acids (PNAs).

[0425] An "isolated nucleic acid" is a nucleic acid molecule that has been separated from a component of its natural environment. An isolated nucleic acid encoding a polypeptide is one or more nucleic acid molecules encoding a polypeptide, including such one or more nucleic acid molecule(s) in a single vector or separate vectors, and one or more nucleic acid molecule(s) present in a single cell or separate cells. A specified nucleic acid sequence also implicitly encompasses conservatively modified variants thereof (e.g., degenerate codon substitutions) and

[0426] The terms "polypeptide" and "protein" are used interchangeably herein to refer to a polymer of amino acid residues. The term applies to amino acid polymers in which one or more amino acid residues are artificial chemical mimics of corresponding naturally occurring amino acids, as well as to naturally occurring and non-naturally occurring amino acid polymers. Unless otherwise specified, a specified polypeptide sequence also implicitly encompasses conservatively modified variants thereof.

[0427] The term "sequence 'identity'" means the extent to which the amino acid / nucleic acid of two sequences are the same (percent) at equivalent positions when the two sequences are optimally aligned; gaps are introduced as necessary to achieve the maximum percent sequence identity, and any conservative substitutions are not considered as part of the sequence identity. To determine the percent sequence identity, the comparison can be achieved by techniques known in the art, for example, using publicly available computer software such as BLAST, BLAST-2, ALIGN, ALIGN-2, or Megalign (DNASTAR) software. Those skilled in the art can determine appropriate parameters to achieve maximal alignment, including any algorithms necessary to achieve the maximum percent sequence identity over the full length of the sequences being compared.

[0428] The term "vector" means a polynucleotide molecule capable of transporting another polynucleotide to which it has been linked. One type of vector is a "plasmid", which refers to a circular double stranded DNA loop into which additional DNA segments can be ligated. Another type of vector is a viral vector, such as an adeno-associated viral vector (AAV or AAV2), wherein additional DNA segments can be ligated into the viral genome. Certain vectors are capable of autonomous replication in a host cell into which they are introduced (e.g., bacterial vectors having a bacterial origin of replication and episomal mammalian vectors). Other vectors (e.g., non-episomal mammalian vectors) can be integrated into the genome of a host cell upon introduction into the host cell, and thereby are replicated along with the host genome. The term "expression vector" or "expression construct" refers to a vector which can be transformed into a host cell, and which contains nucleic acid sequences that direct and / or control the expression of one or more heterologous coding regions operably linked thereto, along with the host cell. An expression construct can include, but is not limited to, sequences that affect or control transcription, translation, and, where introns are present, RNA splicing of a coding region operably linked thereto.

[0429] The terms "host cell," "host cell line," and "host cell culture" are used interchangeably and refer to cells into which exogenous nucleic acid has been introduced, including the progeny of such cells. Host cells include "transformants" and "transformed cells," which include the primary transformed cell and progeny derived therefrom without regard to the number of passages. The progeny can not be completely identical to the parent cell from which it was derived, but may, for example, contain mutations. Mutant progeny that have the same function or biological activity as the parent cell are included herein. Host cells include prokaryotic and eukaryotic host cells, including but not limited to mammalian cells, insect cell lines, plant cells, and fungal cells. Mammalian host cells include human, mouse, rat, canine, monkey, porcine, goat, bovine, equine, and hamster cells, including but not limited to Chinese hamster ovary (CHO) cells, NSO, SP2 cells, HeLa cells, baby hamster kidney (BHK) cells, monkey kidney cells (COS), human hepatocellular carcinoma cells (e.g., Hep G2), A549 cells, 3T3 cells, and HEK-293 cells.Fungal cells include yeast and filamentous fungal cells, including, for example, Pichia pastoris, Pichia finlandica, Pichia trehalophila, Pichia koclamae, Pichia membranaefaciens, Pichia minuta (Ogataea minuta, Pichia lindneri), Pichia opuntiae, Pichia thermotolerans, Pichia salictaria, Pichia guercuum, Pichia pijperi, Pichia stiptis, Pichia methanolica, Pichia sp., Saccharomyces cerevisiae, Saccharomyces sp., Hansenula polymorpha, Kluyveromyces sp., Kluyveromyces lactis, Candida albicans, Aspergillus sp., Aspergillus nidulans, Aspergillus niger, Aspergillus oryzae, Trichoderma reesei, Chrysosporium lucknowense, Fusarium sp., Fusarium gramineum, Fusarium venenatum, Physcomitrella patens, and Neurospora crassa, and Yarrowia lipolytica.

[0430] "Cell," "cell line," "cell culture," and "cells" can be used interchangeably and all such designations include both progeny and derivatives. Thus, the words "transformant" and "transformed cell" include the primary subject cell and cultures derived from it, regardless of the number of transfers. It is further understood that, as a result of either deliberate or inadvertent mutation, not all progeny will be identical to the original transformant. Mutant progeny that have the same function or biological activity as the original transformed cell are included.

[0431] An “antibody drug conjugate” (ADC) is a conjugate that results from linking an antibody (or antigen binding fragment thereof) directly or via a linker to a drug.

[0432] A “drug” (abbreviated: D) is any substance (e.g., therapeutic agent, detectable label, binding agent, etc.) that has a biological or detectable activity and prodrugs that are metabolized in vivo to active agents. Examples of therapeutic agents include cytotoxic agents, chemotherapeutic agents, cell growth inhibitory agents, and immunomodulatory agents. A chemotherapeutic agent is a chemical compound useful in the treatment of cancer. Representative therapeutic agents include cytotoxins, cytotoxic agents, and cell growth inhibitory agents.

[0433] A cytotoxic effect refers to the loss, ablation, and / or killing of target cells. A cytotoxic agent refers to an agent that has a cytotoxic and / or cell growth inhibitory effect on cells. A cell growth inhibitory effect refers to the inhibition of cell proliferation. A cell growth inhibitory agent refers to an agent that has a cell growth inhibitory effect on certain subpopulations of cells, thereby in hibiting the growth and / or expansion of these subpopulations.

[0434] Additional representative therapeutic agents include radioisotopes, chemotherapeutic agents, immunomodulatory agents, anti-angiogenic agents, anti-proliferative agents, pro-apoptotic agents, and cell lytic enzymes (e.g., RNAse). These drug descriptors are not mutually exclusive, and thus, a therapeutic agent can be described using one or more of the above terms. For example, a selected radioisotope is also a cytotoxin. Therapeutic agents can be prepared as pharmaceutically acceptable salts, acids, or derivatives of any of the above. In general, conjugates with radioisotopes as drugs are referred to as radioimmunoconjugates, and with chemotherapeutic agents as drugs are referred to as chemotherapeutic immunoconjugates.

[0435] Examples of cytotoxic agents include, but are not limited to, anthracyclines, auristatins, CC-1065, dolastatins, duocarmycins, enediyines, geldanamycin, maytansines, puromycins, taxoids, vinca alkaloids, SN-38, tubulysins, hemiasterlins, eribulin, Trabectedin, Lurbinectedin, and stereoisomers, isosteres, analogs, or derivatives thereof. Chemotherapeutic agents, plant toxins, other biologically active proteins, enzymes (i.e., ADEPT), radioisotopes, photosensitizers (i.e., for photodynamic therapy) can also be used.

[0436] The term "linker unit," "linker" refers to a chemical moiety or bond that links one end to an antibody and the other end to a drug, and can also be linked to other linkers before being linked to an antibody or drug. Linker attachment to an antibody can be accomplished in a variety of ways, such as via surface lysines, reductive coupling to oxidized carbohydrates, cysteine residues liberated by reduction of interchain disulfides, reactive cysteine residues engineered at specific sites, and tags containing acyl donor glutamines or by engineering of a polypeptide to have reactive endogenous glutamines in the presence of transglutaminase and amines. Various ADC linkage systems are known in the art, including hydrazone-, disulfide- and peptide-based linkages.

[0437] The linker can comprise one or more linker elements. Exemplary linker elements include 6-maleimidocaproyl ("MC"), maleimidopropionyl ("MP"), valine-citrulline ("Val-Cit" or "VC"), alanine-phenylalanine ("Ala-Phe"), p-aminobenzyloxycarbonyl ("PAB"), N-succinimidyl 4-(2-pyridylthio) pentanoate ("SPP"), N-succinimidyl 4-(N-maleimidomethyl) cyclohexane-l-carboxylate ("SMCC", also referred to herein as "MCC"), and N-succinimidyl (4-iodo-acetyl) aminobenzoate ("SIAB").

[0438] The linker can be selected from the following elements or combinations thereof: extenders, spacers, and amino acid units. The linker can be synthesized by methods known in the art. The linker can be a "cleavable linker" that facilitates release of the drug in the cell. For example, an acid-labile linker (e.g., a hydrazone), a protease-sensitive (e.g., a peptidase-sensitive) linker, a photo-labile linker, a dimethyl linker, or a disulfide-containing linker can be used.

[0439] "L-D" is a linker-drug moiety resulting from the attachment of a drug (D) to a linker (L).

[0440] "Drug loading," also referred to as Drug-to-Antibody Ratio (DAR), is the average number of drugs conjugated to each antibody in an ADC. It can range, for example, from about 1 to about 20 drugs per antibody, and in certain embodiments, from about 1 to about 10 drugs per antibody, preferably from the range of 2-8, 2-7, 2-6, 2-5, 2-4, 1-3, 3-4, 3-5, 5-6, 5-7, 5-8, and 6-8. The general formula of the ADCs of the present disclosure includes a collection of antibody-drug conjugates within the aforementioned ranges. In embodiments of the present disclosure, drug loading can be denoted as n, which is a decimal or an integer. Drug loading can be determined by conventional methods such as UV / visible spectroscopy, mass spectrometry, ELISA assays, HIC, and RP-HPLC.

[0441] The term "alkyl" refers to saturated straight-chain or branched-chain aliphatic hydrocarbon groups having from 1 to 20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) carbon atoms (i.e., C 1-20 The alkyl group preferably has from 1 to 12 carbon atoms (i.e., C 1-12 The alkyl group preferably has from 1 to 12 carbon atoms (i.e., C 1-6 Non-limiting examples include: methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, sec-butyl, n-pentyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl, 2-methylbutyl, 3-methylbutyl, n-hexyl, 1-ethyl-2-methylpropyl, 1,1,2-trimethylpropyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 2,2-dimethylbutyl, 1,3-dimethylbutyl, 2-ethylbutyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 2,3-dimethylbutyl, n-heptyl, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 2-ethylpentyl, 3-ethylpentyl, n-octyl, 2,3-dimethylhexyl, 2,4-dimethylhexyl, 2,5-dimethylhexyl, 2,2-dimethylhexyl, 3,3-dimethylhexyl, 4,4-dimethylhexyl, 2-ethylhexyl, 3-ethylhexyl, 4-ethylhexyl, 2-methyl-2-ethylpentyl, 2-methyl-3-ethylpentyl, n-nonyl, 2-methyl-2-ethylhexyl, 2-methyl-3-ethylhexyl, 2,2-diethylpentyl, n-decyl, 3,3-diethylhexyl, 2,2-diethylhexyl, and various branched isomers thereof, and the like. The alkyl group can be substituted or unsubstituted, and when substituted, it can be substituted at any available attachment point with one or more substituents preferably selected from D atoms, halogens, alkoxy groups, haloalkyl groups, haloalkoxy groups, cycloalkyloxy groups, heterocyclyloxy groups, hydroxy groups, hydroxyalkyl groups, cyano groups, amino groups, nitro groups, cycloalkyl groups, heterocyclyl groups, aryl groups, and heteroaryl groups.

[0442] The term "alkenyl" refers to an alkyl group as defined above containing at least one carbon-carbon double bond in the molecule, having from 2 to 12 (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms (i.e., C 2- 12 The alkenyl group preferably has from 2 to 6 carbon atoms (i.e., C 2-6The term "alkenyl" refers to a straight or branched hydrocarbon chain that contains at least one double bond and that contains no terminal double bond(s). Non-limiting examples include: ethenyl, propenyl, isopropenyl, butenyl, and the like. The alkenyl group can be substituted or non-substituted, and when substituted, it can be substituted at any available attachment point with one or more substituents preferably selected from the group consisting of D atoms, alkoxy, halo, haloalkyl, haloalkoxy, cycloalkyloxy, heterocyclyloxy, hydroxy, hydroxyalkyl, cyano, amino, nitro, cycloalkyl, heterocyclyl, aryl, and heteroaryl.

[0443] The term "alkoxy" refers to -O-(alkyl), wherein alkyl is defined above. Non-limiting examples include: methoxy, ethoxy, propyloxy, and butyloxy, and the like. The alkoxy group can be substituted or non-substituted, and when substituted, it can be substituted at any available attachment point with one or more substituents preferably selected from the group consisting of D atoms, halo, alkoxy, haloalkyl, haloalkoxy, cycloalkyloxy, heterocyclyloxy, hydroxy, hydroxyalkyl, cyano, amino, nitro, cycloalkyl, heterocyclyl, aryl, and heteroaryl.

[0444] The term "cycloalkyl" refers to a saturated or partially unsaturated monocyclic all-carbon ring (i.e., monocyclic cycloalkyl) or a multicyclic system (i.e., multicyclic cycloalkyl) having 3 to 20 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) ring atoms (i.e., 3- to 20-membered cycloalkyl). The cycloalkyl group preferably has 3 to 12 ring atoms (i.e., 3- to 12-membered cycloalkyl), more preferably 3 to 8 ring atoms (i.e., 3- to 8-membered cycloalkyl), and most preferably 3 to 6 ring atoms (i.e., 3- to 6-membered cycloalkyl).

[0445] Non-limiting examples of monocyclic cycloalkyl groups include: cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, cyclohexadienyl, cycloheptyl, cycloheptatrienyl, and cyclooctyl, and the like.

[0446] Non-limiting examples of monocyclic cycloalkyl groups include: cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, cyclohexadienyl, cycloheptyl, cycloheptatrienyl, and cyclooctyl, and the like.

[0447] The term "spirocycloalkyl" refers to a polycyclic ring system sharing one carbon atom between rings (referred to as a spiro atom), which can contain one or more double bonds within the rings, or which can contain one or more heteroatoms selected from nitrogen, oxygen, and sulfur within the rings (said nitrogen can optionally be oxidized, i.e., form a nitro oxide; said sulfur can optionally be oxidized, i.e., form a sulfoxide or sulfone, but not -0-0-, -0-S-, or -S-S-), provided that at least one fully carbon ring is present and the point of attachment is on the fully carbon ring, having from 5 to 20 (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) ring atoms (i.e., 5- to 20-membered spirocycloalkyl). The spirocycloalkyl group preferably has from 6 to 14 ring atoms (i.e., 6- to 14-membered spirocycloalkyl), more preferably from 7 to 10 ring atoms (i.e., 7- to 10-membered spirocycloalkyl). The spirocycloalkyl group includes mono- and polyspirocycloalkyl groups (e.g., dispirocycloalkyl groups, etc.), preferably a monospriocycloalkyl group or a dispirocycloalkyl group, more preferably a 3-membered / 4-membered, 3-membered / 5-membered, 3-membered / 6-membered, 4-membered / 4-membered, 4-membered / 5-membered, 4-membered / 6-membered, 5-membered / 3-membered, 5-membered / 4-membered, 5-membered / 5-membered, 5-membered / 6-membered, 5-membered / 7-membered, 6-membered / 3-membered, 6-membered / 4-membered, 6-membered / 5-membered, 6-membered / 6-membered, 6-membered / 7-membered, 7-membered / 5-membered, or 7-membered / 6-membered monospriocycloalkyl group. Non-limiting examples include:

[0448] which can be attached at any position;

[0449] etc.

[0450] The term "fused cycloalkyl" refers to a polycyclic ring system sharing two adjacent carbon atoms between the rings, which is a monocyclic cycloalkyl fused with one or more monocyclic cycloalkyl, or a monocyclic cycloalkyl fused with one or more of heterocyclyl, aryl, or heteroaryl, wherein the point of attachment is on the monocyclic cycloalkyl, which can contain one or more double bonds within its ring, and has 5 to 20 (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) ring atoms (i.e., 5- to 20-membered fused cycloalkyl). The fused cycloalkyl preferably has 6 to 14 ring atoms (i.e., 6- to 14-membered fused cycloalkyl), more preferably 7 to 10 ring atoms (i.e., 7- to 10-membered fused cycloalkyl). The fused cycloalkyl includes bicyclic fused cycloalkyl and polycyclic fused cycloalkyl (such as tricyclic fused cycloalkyl, tetracyclic fused cycloalkyl, etc.), preferably bicyclic fused cycloalkyl or tricyclic fused cycloalkyl, more preferably 3- membered / 4-membered, 3-membered / 5-membered, 3-membered / 6-membered, 4-membered / 4-membered, 4-membered / 5-membered, 4-membered / 6-membered, 5-membered / 3-membered, 5-membered / 4-membered, 5-membered / 5-membered, 5-membered / 6-membered, 5-membered / 7-membered, 6-membered / 3-membered, 6-membered / 4-membered, 6-membered / 5-membered, 6-membered / 6-membered, 6-membered / 7-membered, 7-membered / 5-membered, or 7-membered / 6-membered bicyclic fused cycloalkyl. Non-limiting examples include:

[0451] which can be attached at any position; and the like.

[0452] The term "bridged cycloalkyl" refers to an all-carbon polycyclic ring system sharing two non-adjacent carbon atoms between the rings, which can contain one or more double bonds within its ring, and has 5 to 20 (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) carbon atoms (i.e., 5- to 20-membered bridged cycloalkyl). The bridged cycloalkyl preferably has 6 to 14 carbon atoms (i.e., 6- to 14-membered bridged cycloalkyl), more preferably 7 to 10 carbon atoms (i.e., 7- to 10-membered bridged cycloalkyl). The bridged cycloalkyl includes bicyclic bridged cycloalkyl and polycyclic bridged cycloalkyl (such as tricyclic bridged cycloalkyl, tetracyclic bridged cycloalkyl, etc.), preferably bicyclic bridged cycloalkyl or tricyclic bridged cycloalkyl. Non-limiting examples include:

[0453] which can be attached at any position.

[0454] The cycloalkyl group can be substituted or unsubstituted, and when substituted, it can be substituted at any available point of attachment with one or more substituents preferably selected from D atom, halogen, alkyl, alkoxy, haloalkyl, haloalkoxy, cycloalkyloxy, heterocyclyloxy, hydroxy, hydroxyalkyl, oxo, cyano, amino, nitro, cycloalkyl, heterocyclyl, aryl, and heteroaryl.

[0455] The term "heterocyclyl" refers to a saturated or partially unsaturated monocyclic heterocyclic ring (i.e., monocyclic heterocyclyl) or a polycyclic heterocyclic ring system (i.e., polycyclic heterocyclyl) having at least one (e.g., 1, 2, 3, or 4) heteroatom(s) selected from the group consisting of nitrogen, oxygen, and sulfur (said nitrogen can optionally be oxidized, i.e., form a nitro oxide; said sulfur can optionally be oxidized, i.e., form a sulfoxide or sulfone, but not -O-O-, -O-S-, or -S-S-) in the ring and having from 3 to 20 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) ring atoms (i.e., 3- to 20-membered heterocyclyl). The heterocyclyl group preferably has from 3 to 12 ring atoms (i.e., 3- to 12-membered heterocyclyl), e.g., 4- to 12-membered heterocyclyl having at least one nitrogen atom; further preferably, the heterocyclyl group has from 3 to 8 ring atoms (i.e., 3- to 8-membered heterocyclyl); more preferably, the heterocyclyl group has from 3 to 6 ring atoms (i.e., 3- to 6-membered heterocyclyl); most preferably, the heterocyclyl group has 5 or 6 ring atoms (i.e., 5- or 6-membered heterocyclyl).

[0456] Non-limiting examples of monocyclic heterocyclyl groups include pyrrolidinyl, tetrahydropyranyl, 1,2,3,6-tetrahydropyridinyl, piperidinyl, piperazinyl, morpholinyl, thiomorpholinyl, and homopiperazinyl, and the like.

[0457] Polycyclic heterocyclyl groups include spiroheterocyclyl, fused heterocyclyl, and bridged heterocyclyl groups.

[0458] The term "spiroheterocyclyl" refers to a polycyclic heterocyclic ring system sharing one atom (referred to as the spiro atom) between rings, which can contain one or more double bonds in the ring and which has at least one (e.g., 1, 2, 3, or 4) heteroatom(s) selected from the group consisting of nitrogen, oxygen, and sulfur (said nitrogen can optionally be oxidized, i.e., form a nitro oxide; said sulfur can optionally be oxidized, i.e., form a sulfoxide or sulfone, but not -O-O-, -O-S-, or -S-S-) in the ring, provided that at least one monocyclic heterocyclyl group is present and the point of attachment is on the monocyclic heterocyclyl group, and which has from 5 to 20 (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) ring atoms (i.e., 5- to 20-membered spiroheterocyclyl). The spiroheterocyclyl group preferably has from 6 to 14 ring atoms (i.e., 6- to 14-membered spiroheterocyclyl), more preferably from 7 to 10 ring atoms (i.e., 7- to 10-membered spiroheterocyclyl). The spiroheterocyclyl group includes mono- and polyspiroheterocyclyl groups (e.g., dispiroheterocyclyl groups and the like), preferably a monosprioheterocyclyl group or a dispiroheterocyclyl group, more preferably a 3- membered / 4-membered, 3-membered / 5-membered, 3-membered / 6-membered, 4-membered / 4-membered, 4-membered / 5-membered, 4-membered / 6-membered, 5-membered / 3-membered, 5-membered / 4-membered, 5-membered / 5-membered, 5-membered / 6-membered, 5-membered / 7-membered, 6-membered / 3-membered, 6-membered / 4-membered, 6-membered / 5-membered, 6-membered / 6-membered, 6-membered / 7-membered, 7-membered / 5-membered, or 7-membered / 6-membered monosprioheterocyclyl group. Non-limiting examples include:

[0459] etc.

[0460] The term "fused heterocyclyl" refers to a polycyclic heterocyclic ring system sharing adjacent atoms between rings, which can contain one or more double bonds within the ring, and which contains at least one (e.g., 1, 2, 3, or 4) heteroatom(s) selected from nitrogen, oxygen, and sulfur (said nitrogen optionally oxidized, i.e., N-oxide; said sulfur optionally oxidized, i.e., sulfoxide or sulfone, but not including -0-0-, -0-S-, or -S-S-) within the ring, which is fused to a monocyclic heterocyclyl group or to one or more monocyclic heterocyclyl groups, or to one or more of a cycloalkyl, aryl, or heteroaryl group, with the point of attachment being on the monocyclic heterocyclyl group, and having from 5 to 20 (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) ring atoms (i.e., 5- to 20-membered fused heterocyclyl). The fused heterocyclyl group preferably has from 6 to 14 ring atoms (i.e., 6- to 14-membered fused heterocyclyl), more preferably from 7 to 10 ring atoms (i.e., 7- to 10-membered fused heterocyclyl). The fused heterocyclyl group includes bicyclic and polycyclic fused heterocyclyl groups (e.g., tricyclic fused heterocyclyl groups, tetracyclic fused heterocyclyl groups, etc.), preferably bicyclic fused heterocyclyl groups or tricyclic fused heterocyclyl groups, more preferably 3 / 4-, 3 / 5-, 3 / 6-, 4 / 4-, 4 / 5-, 4 / 6-, 5 / 3-, 5 / 4-, 5 / 5-, 5 / 6-, 5 / 7-, 6 / 3-, 6 / 4-, 6 / 5-, 6 / 6-, 6 / 7-, 7 / 5-, or 7 / 6 bicyclic fused heterocyclyl groups. Non-limiting examples include:

[0461] etc.

[0462] The term "bridged heterocyclyl" refers to a polycyclic heterocyclic ring system sharing two non-adjacent atoms between rings, which can contain one or more double bonds within the ring, and which contains at least one (e.g., 1, 2, 3, or 4) heteroatom(s) selected from nitrogen, oxygen, and sulfur (said nitrogen optionally oxidized, i.e., N-oxide; said sulfur optionally oxidized, i.e., sulfoxide or sulfone, but not including -0-0-, -0-S-, or -S-S-) within the ring, which has from 5 to 20 (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) ring atoms (i.e., 5- to 20-membered bridged heterocyclyl). The bridged heterocyclyl group preferably has from 6 to 14 ring atoms (i.e., 6- to 14-membered bridged heterocyclyl), more preferably from 7 to 10 ring atoms (i.e., 7- to 10-membered bridged heterocyclyl). The bridged heterocyclyl group includes bicyclic and polycyclic bridged heterocyclyl groups (e.g., tricyclic bridged heterocyclyl groups, tetracyclic bridged heterocyclyl groups, etc.), preferably bicyclic bridged heterocyclyl groups or tricyclic bridged heterocyclyl groups. Non-limiting examples include:

[0463] etc.

[0464] Heterocyclyl can be substituted or non-substituted, and when substituted, it can be substituted at any available point of attachment with one or more substituents preferably selected from D atoms, halogen, alkyl, alkoxy, haloalkyl, haloalkoxy, cycloalkyloxy, heterocyclyloxy, hydroxy, hydroxyalkyl, oxo, cyano, amino, nitro, cycloalkyl, heterocyclyl, aryl, and heteroaryl.

[0465] The term "aryl" refers to a monocyclic all-carbon aromatic ring having a conjugated pi-electron system (i.e., monocyclic aryl) or a polycyclic aromatic ring system (i.e., polycyclic aryl) having 6 to 14 (e.g., 6, 7, 8, 9, 10, 11, 12, 13, or 14) ring atoms (i.e., 6- to 14-membered aryl). The aryl group preferably has 6 to 10 ring atoms (i.e., 6- to 10-membered aryl). The monocyclic aryl group is exemplified by phenyl. The polycyclic aryl group is exemplified by, without limitation, naphthyl, anthryl, phenanthryl, and the like. The polycyclic aryl group also includes phenyl or naphthyl fused with one or more heterocyclyl or cycloalkyl groups, where the point of attachment is on the phenyl or naphthyl group, and in this case, the number of ring atoms continues to represent the number of ring atoms in the polycyclic aromatic ring system, which is exemplified by, without limitation:

[0466] etc.

[0467] Aryl can be substituted or non-substituted, and when substituted, it can be substituted at any available point of attachment with one or more substituents preferably selected from D atoms, halogen, alkyl, alkoxy, haloalkyl, haloalkoxy, cycloalkyloxy, heterocyclyloxy, hydroxy, hydroxyalkyl, oxo, cyano, amino, nitro, cycloalkyl, heterocyclyl, aryl, and heteroaryl.

[0468] The term "heteroaryl" refers to a monocyclic heteroaryl ring (i.e., monocyclic heteroaryl) or a polycyclic heteroaryl ring system (i.e., polycyclic heteroaryl) having a conjugated π-electron system, containing at least one (e.g., 1, 2, 3 or 4) heteroatoms selected from nitrogen, oxygen and sulfur (the nitrogen may optionally be oxidized, i.e., to form nitrogen oxides; the sulfur may optionally be oxidized, i.e., to form sulfoxides or sulfones, but excluding -OO-, -OS- or -SS-), having 5 to 14 (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14) ring atoms (i.e., 5 to 14-membered heteroaryl). The heteroaryl group is preferably a heteroaryl group having 5 to 10 ring atoms (i.e., a 5 to 10-membered heteroaryl group), more preferably a monocyclic heteroaryl group having 5 or 6 ring atoms (i.e., a 5 or 6-membered monocyclic heteroaryl group) or a bicyclic heteroaryl group having 8 to 10 ring atoms (i.e., an 8 to 10-membered bicyclic heteroaryl group), and most preferably a 5 or 6-membered monocyclic heteroaryl group containing 1, 2 or 3 heteroatoms selected from nitrogen, oxygen and sulfur or an 8 to 10-membered bicyclic heteroaryl group containing 1, 2 or 3 heteroatoms selected from nitrogen, oxygen and sulfur.

[0469] Non-limiting examples of the aforementioned monocyclic heteroaryl groups include: furanyl, thiopheneyl, thiazolyl, isothiazolyl, oxazolyl, isoxazolyl, oxadiazolyl, thiadiazolyl, imidazolyl, pyrazolyl, triazolyl, tetrazolyl, furazonyl, pyrroleyl, N-alkylpyrroleyl, pyridyl, pyrimidinyl, pyridoneyl, N-alkylpyridone (e.g.) (etc.), pyrazinyl, pyridazinyl, etc.

[0470] Non-limiting examples of the polycyclic heteroaryl groups include: indolyl, indazole, quinolinyl, isoquinolinyl, quinoxalinyl, phthalazinyl, benzimidazolyl, benzothiophene, quinazolinyl, benzothiazolyl, carbazole, etc. The polycyclic heteroaryl groups also include monocyclic heteroaryl groups fused with one or more aryl groups, wherein the connecting point is on the aromatic ring, and in this case, the number of ring atoms continues to represent the number of ring atoms in the polycyclic heteroaryl ring system. The polycyclic heteroaryl groups also include monocyclic heteroaryl groups fused with one or more cycloalkyl or heterocyclic groups, wherein the connecting point is on the monocyclic heteroaryl ring, and in this case, the number of ring atoms continues to represent the number of ring atoms in the polycyclic heteroaryl ring system. Non-limiting examples include:

[0471] wait.

[0472] The heteroaryl group can be substituted or unsubstituted. When substituted, it can be substituted at any usable connection point. The substituent is preferably selected from one or more of the following: D atom, halogen, alkyl, alkoxy, haloalkyl, haloalkoxy, cycloalkyloxy, heterocyclic oxy, hydroxy, hydroxyalkyl, cyano, amino, nitro, cycloalkyl, heterocyclic, aryl, and heteroaryl.

[0473] The above cycloalkyl, heterocyclyl, aryl and heteroaryl include a residue derived from removal of one hydrogen atom from a parent ring atom, or a residue derived from removal of two hydrogen atoms from the same ring atom or two different ring atoms of the parent, i.e. "divalent cycloalkyl", "divalent heterocyclyl", "arylene" and "heteroarylene".

[0474] In the chemical structure of the compounds of the present disclosure, the bond represents unspecified configuration, i.e. if there are chiral isomers in the chemical structure, the bond may be or simultaneously include both configurations.

[0475] The compounds of the present disclosure include all suitable isotopic variations of the compounds. The term "isotopic variations" means the compounds wherein at least one atom has been replaced by an atom having the same atomic number but an atomic mass different from the atomic mass usually found in nature. Examples of isotopes that can be incorporated into a compound of the present disclosure include stable and radioactive isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, fluorine, chlorine, bromine, and iodine, such as 2 H (deuterium, D), 3 H (tritium, T), 11 C, 13 C, 14 C, 15 N, 17 O, 18 O, 32 p, 33 p, 33 S, 34 S, 35 S, 36 S, 18 F, 36 Cl, 82 Br, 123 I, 124 I, 125 I, 129 I, and 131 I, preferably deuterium.

[0476] Deuterated drugs have advantages of reducing side effects, increasing drug stability, enhancing efficacy, prolonging drug biological half-life, etc. compared to non-deuterated drugs. All isotopic variations of the compounds of the present disclosure, whether radioactive or not, are included within the scope of the present disclosure. Each of the available hydrogen atoms attached to a carbon atom can be independently replaced by a deuterium atom, wherein the replacement of deuterium can be partial or complete, and the partial replacement of deuterium means that at least one hydrogen is replaced by at least one deuterium.

[0477] "Optional" or "optionally" means that the subsequently described event or circumstance can or can not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0478] The term "pharmaceutical composition" denotes a mixture of one or more of the antibodies, immunoconjugates or antibody drug conjugates described herein with other chemical components such as physiologically / pharmaceutically-acceptable carriers, diluents or excipients.

[0479] The term "pharmaceutically-acceptable carrier, diluent or excipient" refers to a component of a pharmaceutical formulation that does not itself induce the production of antibodies in recipients, that is well-tolerated in subjects, and that does not have any serious adverse side effects with the dosage ranges and concentrations employed. Pharmaceutically-acceptable carriers, diluents or excipients include, but are not limited to, buffers, excipients, stabilizers, or preservatives.

[0480] The term "subject" or "individual" includes both human and non-human animals. Non-human animals include all vertebrates, e.g., mammals and non-mammals, such as non-human primates, sheep, dogs, cows, chickens, amphibians, and reptiles. The terms "patient" or "subject" are used interchangeably herein unless otherwise indicated. In some embodiments, the individual or subject is a human.

[0481] "Administering" or "administration," when applied to an animal, human, test subject, cell, tissue, organ, or biological fluid, means the contact of an exogenous drug, therapeutic agent, diagnostic agent, or composition with the animal, human, test subject, cell, tissue, organ, or biological fluid.

[0482] The term "sample" refers to a collection (e.g., fluid, cell, or tissue) isolated from a subject, as well as fluids, cells, or tissues present within a subject. Exemplary samples are biological fluids such as blood, serum and serosal fluids, plasma, lymphatic fluid, urine, saliva, cyst fluid, lacrimal fluid, fecal matter, sputum, mucosal secretions of secretory tissues or organs, vaginal secretions, ascites, pleural, pericardial, peritoneal, abdominal and other body cavity fluids, fluids collected by bronchial lavage, synovial fluid, liquid solutions in contact with a subject or biological source, e.g., culture media (including conditioned media), lavage fluids, and the like, tissue biopsy samples, fine needle aspirates, surgically removed tissues, organ cultures, or cell cultures.

[0483] "Treatment" and "treating" (and grammatical variations thereof) refer to clinical intervention by which an individual's clinical status is modified. Treatment can be performed for prophylaxis or during the course of clinical pathology. Desirable effects of treatment include, but are not limited to, preventing occurrence or reoccurrence of disease, alleviating symptoms, diminishment / decrease of any direct or indirect pathological consequences of the disease, preventing metastasis, decreasing the rate of disease progression, amelioration or palliation of the disease state, and remission or improved prognosis.

[0484] An "effective amount" is generally an amount that is sufficient to reduce the severity and / or frequency of symptoms, eliminate the symptoms and / or their underlying cause, prevent symptoms and / or their underlying cause from occurring, or improve or ameliorate an injury or illness caused or associated with a disease state (e.g., a lung disease). In some embodiments, an effective amount is a therapeutically effective amount or a prophylactically effective amount.

[0485] A "therapeutically effective amount" is an amount that is sufficient to treat a disease state or symptoms, particularly states or symptoms associated with the disease state, or otherwise prevent, hinder, retard, or reverse the progress of the disease state or any other undesirable symptoms associated with the disease in any way. A "prophylactically effective amount" is an amount that will have the intended prophylactic effect, such as preventing or delaying the onset (or reoccurrence) of the disease state, or reducing the likelihood of the onset (or reoccurrence) of the disease state or associated symptoms, when administered to a subject. Complete treatment or prevention need not occur in order for a dose to be considered an effective therapeutic or prophylactic amount. Thus, a therapeutically or prophylactically effective amount can be administered in one or more doses. "Therapeutically effective amount" and "prophylactically effective amount" can vary depending on factors such as the disease state of the individual, the age, sex, and weight of the individual, and the ability of the therapeutic agent or combination of therapeutic agents to elicit a desired response in the individual. Exemplary indicators of an effective therapeutic agent or combination of therapeutic agents include, for example, improved health status of the patient.

[0486] Anti-B7-H3 antibodies of the disclosure

[0487] The present disclosure provides anti-B7-H3 antibodies, which have a number of advantageous properties, such as good therapeutic activity, safety, pharmacokinetic properties, and drugability (e.g., solubility, viscosity, purity, and stability, etc.).

[0488] Exemplary anti-B7-H3 antibodies

[0489] Exemplarily, an anti-B7-H3 antibody of the present disclosure comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises HCDR1, HCDR2, and HCDR3, and the light chain variable region comprises LCDR1, LCDR2, and LCDR3, wherein:

[0490] (1) the amino acid sequence of HCDR1 of the heavy chain variable region is set forth in SEQ ID NO: 14, the amino acid sequence of HCDR2 is set forth in SEQ ID NO: 15, and the amino acid sequence of HCDR3 is set forth in SEQ ID NO: 16, and the amino acid sequence of LCDR1 of the light chain variable region is set forth in SEQ ID NO: 17, the amino acid sequence of LCDR2 is set forth in SEQ ID NO: 90, and the amino acid sequence of LCDR3 is set forth in SEQ ID NO: 19, wherein:

[0491] YTSRLHX1 SEQ ID NO: 90;

[0492] X1is S or E; or

[0493] (2) the amino acid sequence of HCDR1, HCDR2, and HCDR3 of the heavy chain variable region is set forth in SEQ ID NO: 8, 88, and 10, respectively, and the amino acid sequence of LCDR1, LCDR2, and LCDR3 of the light chain variable region is set forth in SEQ ID NO: 89, 12, and 13, respectively, wherein:

[0494] NINPFX2GGTNYNEKFKS SEQ ID NO: 88;

[0495] RSSQTIVRSX3GX4TYLE SEQ ID NO: 89;

[0496] X2is Q or N;

[0497] X3is E or D; X4is N or Q; or

[0498] (3) the amino acid sequence of HCDR1, HCDR2, and HCDR3 of the heavy chain variable region is set forth in SEQ ID NO: 93, 144, and 95, respectively, and the amino acid sequence of LCDR1, LCDR2, and LCDR3 of the light chain variable region is set forth in SEQ ID NO: 145, 146, and 98, respectively, wherein:

[0499] WIYPRDASX5YSERFKD SEQ ID NO: 144;

[0500] RSSKSLX6HSNGX7TYLF SEQ ID NO: 145;

[0501] QMSNLAX8 SEQ ID NO: 146;

[0502] X5is Q or N;

[0503] X6is T or L;

[0504] X7 is I or H;

[0505] X8 is T or S.

[0506] In exemplary embodiments, an anti-B7-H3 antibody of the present disclosure comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises a HCDR1, a HCDR2, and a HCDR3, and the light chain variable region comprises a LCDR1, a LCDR2, and a LCDR3, wherein:

[0507] the amino acid sequence of the HCDR1 of the heavy chain variable region is set forth in SEQ ID NO: 14, the amino acid sequence of the HCDR2 is set forth in SEQ ID NO: 15, and the amino acid sequence of the HCDR3 is set forth in SEQ ID NO: 16, and the amino acid sequence of the LCDR1 of the light chain variable region is set forth in SEQ ID NO: 17, the amino acid sequence of the LCDR2 is set forth in SEQ ID NO: 90, and the amino acid sequence of the LCDR3 is set forth in SEQ ID NO: 19, wherein:

[0508] YTSRLHX1 SEQ ID NO: 90;

[0509] X1 is S or E.

[0510] In exemplary embodiments, an anti-B7-H3 antibody of the present disclosure comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises a HCDR1, a HCDR2, and a HCDR3, and the light chain variable region comprises a LCDR1, a LCDR2, and a LCDR3, wherein:

[0511] the amino acid sequence of the HCDR1 of the heavy chain variable region is set forth in SEQ ID NO: 8, the amino acid sequence of the HCDR2 is set forth in SEQ ID NO: 88, and the amino acid sequence of the HCDR3 is set forth in SEQ ID NO: 10, and the amino acid sequence of the LCDR1 of the light chain variable region is set forth in SEQ ID NO: 89, the amino acid sequence of the LCDR2 is set forth in SEQ ID NO: 12, and the amino acid sequence of the LCDR3 is set forth in SEQ ID NO: 13, wherein:

[0512] NINPFX2GGTNYNEKFKS SEQ ID NO: 88;

[0513] RSSQTIVRSX3GX4TYLE SEQ ID NO: 89;

[0514] X2 is Q or N;

[0515] X3 is E or D; X4 is N or Q.

[0516] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises a HCDR1, a HCDR2, and a HCDR3, and the light chain variable region comprises a LCDR1, a LCDR2, and a LCDR3, wherein:

[0517] the amino acid sequence of the HCDR1 of the heavy chain variable region is set forth in SEQ ID NO: 93, the amino acid sequence of the HCDR2 is set forth in SEQ ID NO: 144, and the amino acid sequence of the HCDR3 is set forth in SEQ ID NO: 95, and the amino acid sequence of the LCDR1 of the light chain variable region is set forth in SEQ ID NO: 145, the amino acid sequence of the LCDR2 is set forth in SEQ ID NO: 146, and the amino acid sequence of the LCDR3 is set forth in SEQ ID NO: 98, wherein:

[0518] WIYPRDASX5YSERFKD SEQ ID NO: 144;

[0519] RSSKSLX6HSNGX7TYLF SEQ ID NO: 145;

[0520] QMSNLAX8 SEQ ID NO: 146;

[0521] X5 is Q or N;

[0522] X6 is T or L;

[0523] X7 is I or H;

[0524] X8 is T or S.

[0525] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises a HCDR1, a HCDR2, and a HCDR3, and the light chain variable region comprises a LCDR1, a LCDR2, and a LCDR3, wherein:

[0526] (1) the amino acid sequence of HCDR1, the amino acid sequence of HCDR2, and the amino acid sequence of HCDR3 of the heavy chain variable region are set forth in SEQ ID NO: 14, SEQ ID NO: 15, and SEQ ID NO: 16, respectively, and the amino acid sequence of LCDR1, the amino acid sequence of LCDR2, and the amino acid sequence of LCDR3 of the light chain variable region are set forth in SEQ ID NO: 17, SEQ ID NO: 18, and SEQ ID NO: 19, respectively; or

[0527] (2) the amino acid sequence of HCDR1, the amino acid sequence of HCDR2, and the amino acid sequence of HCDR3 of the heavy chain variable region are set forth in SEQ ID NO: 8, SEQ ID NO: 32, and SEQ ID NO: 10, respectively, and the amino acid sequence of LCDR1, the amino acid sequence of LCDR2, and the amino acid sequence of LCDR3 of the light chain variable region are set forth in SEQ ID NO: 30, SEQ ID NO: 12, and SEQ ID NO: 13, respectively; or

[0528] (3) the amino acid sequence of HCDR1, the amino acid sequence of HCDR2, and the amino acid sequence of HCDR3 of the heavy chain variable region are set forth in SEQ ID NO: 93, SEQ ID NO: 114, and SEQ ID NO: 95, respectively, and the amino acid sequence of LCDR1, the amino acid sequence of LCDR2, and the amino acid sequence of LCDR3 of the light chain variable region are set forth in SEQ ID NO: 111, SEQ ID NO: 112, and SEQ ID NO: 98, respectively.

[0529] In some embodiments, the anti-B7-H3 antibody of any of the preceding embodiments, the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2, and LCDR3 of the light chain variable region are defined according to the Rabat numbering convention.

[0530] Illustratively, an anti-B7-H3 antibody of the present disclosure, comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises HCDR1, HCDR2, and HCDR3, and the light chain variable region comprises LCDR1, LCDR2, and LCDR3, wherein:

[0531] the amino acid sequence of HCDR1, the amino acid sequence of HCDR2, and the amino acid sequence of HCDR3 of the heavy chain variable region are as set forth in SEQ ID NO: 8, SEQ ID NO: 32, and SEQ ID NO: 10, respectively, and the amino acid sequence of LCDR1, the amino acid sequence of LCDR2, and the amino acid sequence of LCDR3 of the light chain variable region are as set forth in SEQ ID NO: 30, SEQ ID NO: 12, and SEQ ID NO: 13, respectively;

[0532] the HCDR1, the HCDR2, and the HCDR3 of the heavy chain variable region and the LCDR1, the LCDR2, and the LCDR3 of the light chain variable region are defined according to the Kabat numbering convention.

[0533] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises HCDR1, HCDR2, and HCDR3, and the light chain variable region comprises LCDR1, LCDR2, and LCDR3, wherein:

[0534] the amino acid sequence of HCDR1, the amino acid sequence of HCDR2, and the amino acid sequence of HCDR3 of the heavy chain variable region are as set forth in SEQ ID NO: 8, SEQ ID NO: 32, and SEQ ID NO: 10, respectively, and the amino acid sequence of LCDR1, the amino acid sequence of LCDR2, and the amino acid sequence of LCDR3 of the light chain variable region are as set forth in SEQ ID NO: 30, SEQ ID NO: 12, and SEQ ID NO: 13, respectively;

[0535] the HCDR1, the HCDR2, and the HCDR3 of the heavy chain variable region and the LCDR1, the LCDR2, and the LCDR3 of the light chain variable region are defined according to the Kabat numbering convention.

[0536] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises HCDR1, HCDR2, and HCDR3, and the light chain variable region comprises LCDR1, LCDR2, and LCDR3, wherein:

[0537] the amino acid sequence of HCDR1, the amino acid sequence of HCDR2, and the amino acid sequence of HCDR3 of the heavy chain variable region are as set forth in SEQ ID NO: 93, SEQ ID NO: 114, and SEQ ID NO: 95, respectively, and the amino acid sequence of LCDR1, the amino acid sequence of LCDR2, and the amino acid sequence of LCDR3 of the light chain variable region are as set forth in SEQ ID NO: 111, SEQ ID NO: 112, and SEQ ID NO: 98, respectively;

[0538] the HCDR1, the HCDR2, and the HCDR3 of the heavy chain variable region and the LCDR1, the LCDR2, and the LCDR3 of the light chain variable region are defined according to the Kabat numbering convention.

[0539] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain variable region and a light chain variable region, wherein:

[0540] (1) the amino acid sequence of the heavy chain variable region is as set forth in SEQ ID NO: 66, and the amino acid sequence of the light chain variable region is as set forth in SEQ ID NO: 71; or

[0541] (2) the amino acid sequence of the heavy chain variable region is as set forth in SEQ ID NO: 40, and the amino acid sequence of the light chain variable region is as set forth in SEQ ID NO: 47;

[0542] (3) the amino acid sequence of the heavy chain variable region is as set forth in SEQ ID NO: 125, and the amino acid sequence of the light chain variable region is as set forth in SEQ ID NO: 127.

[0543] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain variable region and a light chain variable region, wherein:

[0544] the amino acid sequence of the heavy chain variable region is as set forth in SEQ ID NO: 66, and the amino acid sequence of the light chain variable region is as set forth in SEQ ID NO: 71.

[0545] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain variable region and a light chain variable region, wherein:

[0546] the amino acid sequence of the heavy chain variable region is as set forth in SEQ ID NO: 40, and the amino acid sequence of the light chain variable region is as set forth in SEQ ID NO: 47.

[0547] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain variable region and a light chain variable region, wherein:

[0548] The amino acid sequence of the heavy chain variable region is set forth in SEQ ID NO: 125, and the amino acid sequence of the light chain variable region is set forth in SEQ ID NO: 127.

[0549] Exemplary anti-B7-H3 antibodies of the present disclosure, comprise a heavy chain and a light chain, wherein:

[0550] (1) the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 78, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 83; or

[0551] the amino acid sequence of the heavy chain is set forth in amino acid residues 1 to 447 of SEQ ID NO: 78, and the amino acid sequence of the light chain is set forth in amino acid residues 1 to 214 of SEQ ID NO: 83; or

[0552] (2) the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 55, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 62; or

[0553] the amino acid sequence of the heavy chain is set forth in amino acid residues 1 to 449 of SEQ ID NO: 55, and the amino acid sequence of the light chain is set forth in amino acid residues 1 to 219 of SEQ ID NO: 62; or

[0554] (3) the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 139, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 141; or

[0555] the amino acid sequence of the heavy chain is set forth in amino acid residues 1 to 449 of SEQ ID NO: 139, and the amino acid sequence of the light chain is set forth in amino acid residues 1 to 217 of SEQ ID NO: 141.

[0556] Exemplary anti-B7-H3 antibodies of the present disclosure, comprise a heavy chain and a light chain, wherein:

[0557] the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 78, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 83; or

[0558] the amino acid sequence of the heavy chain is set forth in amino acid residues 1 to 447 of SEQ ID NO: 78, and the amino acid sequence of the light chain is set forth in amino acid residues 1 to 214 of SEQ ID NO: 83.

[0559] Exemplary anti-B7-H3 antibodies of the present disclosure, comprise a heavy chain and a light chain, wherein:

[0560] the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 55, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 62; or

[0561] the amino acid sequence of the heavy chain is set forth in amino acid residues 1 to 449 of SEQ ID NO: 55, and the amino acid sequence of the light chain is set forth in amino acid residues 1 to 219 of SEQ ID NO: 62.

[0562] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain and a light chain, wherein:

[0563] the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 139, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 141; or

[0564] the amino acid sequence of the heavy chain is set forth in amino acid residues 1 to 449 of SEQ ID NO: 139, and the amino acid sequence of the light chain is set forth in amino acid residues 1 to 217 of SEQ ID NO: 141.

[0565] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain and a light chain, wherein:

[0566] the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 78, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 83.

[0567] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain and a light chain, wherein:

[0568] the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 55, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 62.

[0569] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain and a light chain, wherein:

[0570] the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 139, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 141.

[0571] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain and a light chain, wherein:

[0572] (1) the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 108, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 83; or

[0573] the amino acid sequence of the heavy chain is set forth in amino acid residues 1 to 447 of SEQ ID NO: 108, and the amino acid sequence of the light chain is set forth in amino acid residues 1 to 214 of SEQ ID NO: 83; or

[0574] (2) the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 105, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 62; or

[0575] the amino acid sequence of the heavy chain is set forth in amino acid residues 1 to 449 of SEQ ID NO: 105, and the amino acid sequence of the light chain is set forth in amino acid residues 1 to 219 of SEQ ID NO: 62; or

[0576] (3) the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 143, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 141; or

[0577] the amino acid sequence of the heavy chain is set forth in amino acid residues 1 to 449 of SEQ ID NO: 143, and the amino acid sequence of the light chain is set forth in amino acid residues 1 to 217 of SEQ ID NO: 141.

[0578] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain and a light chain, wherein:

[0579] the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 108, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 83; or

[0580] the amino acid sequence of the heavy chain is set forth in amino acid residues 1 to 447 of SEQ ID NO: 108, and the amino acid sequence of the light chain is set forth in amino acid residues 1 to 214 of SEQ ID NO: 83.

[0581] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain and a light chain, wherein:

[0582] the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 105, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 62; or

[0583] the amino acid sequence of the heavy chain is set forth in amino acid residues 1 to 449 of SEQ ID NO: 105, and the amino acid sequence of the light chain is set forth in amino acid residues 1 to 219 of SEQ ID NO: 62.

[0584] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain and a light chain, wherein:

[0585] the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 143, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 141; or

[0586] the amino acid sequence of the heavy chain is set forth in residues 1-449 of SEQ ID NO: 143, and the amino acid sequence of the light chain is set forth in residues 1-217 of SEQ ID NO: 141.

[0587] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain and a light chain, wherein:

[0588] the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 108, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 83.

[0589] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain and a light chain, wherein:

[0590] the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 105, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 62.

[0591] Exemplary anti-B7-H3 antibodies of the present disclosure comprise a heavy chain and a light chain, wherein:

[0592] the amino acid sequence of the heavy chain is set forth in SEQ ID NO: 143, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 141.

[0593] Antibodies provided herein can also comprise an amino acid sequence having at least 80% (e.g., at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%) sequence identity to the above amino acid sequences, e.g., CDR sequences, variable region sequences, heavy chain or light chain sequences.

[0594] Antibody structure

[0595] In some embodiments, the antibodies provided herein are full-length antibodies.

[0596] In some embodiments, the antibodies provided herein are antibody fragments.

[0597] In some embodiments, the antibody fragment is a Fab, Fab', Fab'-SH or F(ab')2 fragment, particularly a Fab fragment. "Fab" is a monovalent fragment consisting of the VL, VH, CL and CH1 domains. "Fab fragments" can be produced by papain digestion of an antibody. "Fab'" contains the VL, CL, and VH and CH1, and also contains the region between the CH1 and CH2 domains, so that a disulfide bond can be formed between the two heavy chains in the two Fab' fragments, to form an F(ab')2 molecule. "Fab'-SH" is a Fab' fragment in which the cysteine residue of the constant region has a free thiol group. "F(ab')2" comprises a bivalent fragment comprising two Fab fragments that are linked by disulfide bonds in the hinge region.

[0598] In some embodiments, the antibody fragment is a diabody, triabody or tetrabody. Diabodies are antibody fragments with two antigen binding sites, comprising the VHand VLjoined by a short linker that does not allow pairing between the two domains on the same chain. This forces the domains to pair with the complementary domains of another chain and makes two antigen binding sites, which can be the same or different.

[0599] In some embodiments, the antibody fragment is a single chain Fab fragment. A "single chain Fab fragment" or "scFab" is a polypeptide consisting of a VH, CH1, VL, CL and a linker, wherein the antibody domains and the linker have one of the following orders in N-terminal to C-terminal direction: a) VH-CH1-linker-VL-CL, b) VL-CL-linker-VH-CH1, c) VH-CL-linker-VL-CH1 or d) VL-CH1-linker-VH-CL. In some embodiments, the linker is a polypeptide of at least 30 amino acids. In some embodiments, the linker is a polypeptide of between 32 and 50 amino acids. The single chain Fab fragments are stabilized via the native disulfide bond between CL and CH1. Additionally, these single chain Fab molecules can be further stabilized by the creation of an interchain disulfide bond by the insertion of a cysteine residue, for example at position 44 in the heavy chain variable region and at position 100 in the light chain variable region, according to Kabat numbering.

[0600] In some embodiments, the antibody fragment is a Fv fragment consisting of the VH and VL domains of a single arm of an antibody.

[0601] In some embodiments, the antibody fragment is a single chain variable fragment (scFv). An "scFv" is a fusion protein comprising at least one antibody fragment comprising a light chain variable region and at least one antibody fragment comprising a heavy chain variable region, wherein the light chain variable region and the heavy chain variable region are connected in tandem by a short, flexible peptide linker, is capable of being expressed as a single chain polypeptide, and wherein the scFv retains the specificity of the intact antibody from which it is derived. Unless specifically indicated otherwise, scFv herein can have the VL and VH variable regions in either order, e.g., an scFv can comprise VL-linker-VH or can comprise VH-linker-VL, with respect to the N- and C-termini of the polypeptide.

[0602] In some embodiments, the antibody fragment is a dsFv, which is obtained by linking polypeptides in which one amino acid residue in each of the VH and VL is substituted with a cysteine residue, via a disulfide bond between the cysteine residues. The amino acid residue substituted with the cysteine residue can be selected based on the three-dimensional structure prediction of the antibody according to known methods.

[0603] In some embodiments, the antibody fragment is a single domain antibody (dAb). A single domain antibody is an antibody fragment comprising all or a portion of the variable domain of the heavy chain or all or a portion of the variable domain of the light chain of an antibody.

[0604] In some embodiments, an antibody provided herein is a chimeric antibody. In some embodiments, a chimeric antibody comprises a non-human variable region (e.g., a variable region derived from a mouse, rat, hamster, rabbit, or non-human primate, such as a monkey) and a human constant region. In some embodiments, a chimeric antibody is a "class switched" antibody in which the class or subclass has been changed from that of the parent antibody.

[0605] In some embodiments, an antibody is a humanized antibody. Typically, a non-human antibody is humanized by reducing its immunogenicity to humans while retaining its specificity and affinity for the original antigen. Generally, a humanized antibody comprises one or more variable regions in which CDRs or portions thereof are derived from a non-human antibody, while FRs or portions thereof are derived from human antibodies. Optionally, a humanized antibody will also comprise a portion of a human constant region. In some embodiments, some FR residues in a humanized antibody can be substituted with corresponding residues from the non-human antibody (e.g., the antibody providing the CDR sequences).

[0606] Variants of Anti-B7-H3 Antibodies

[0607] In certain embodiments, amino acid sequence variants of the anti-B7-H3 antibodies provided herein are encompassed. For example, it can be desirable to improve the binding affinity and / or other biological properties of the antibody. Amino acid sequence variants of the antibody can be prepared by introducing appropriate modifications into the nucleotide sequence encoding the antibody, or by peptide synthesis. Such modifications include, for example, deletions from, and / or insertions into, and / or substitutions of, residues within the amino acid sequences of the anti-B7-H3 antibodies. Any combination of deletion, insertion, and substitution can be made to arrive at the final construct, provided that the final construct possesses the desired characteristics, e.g., antigen binding properties.

[0608] Substitution, insertion, and deletion variants

[0609] In certain embodiments, antibody variants with one or more amino acid substitutions are provided. Sites of interest for substitutional mutagenesis include the CDRs and FRs. Conservative substitutions are shown in Table B under the heading of "preferred substitutions." More substantial changes are provided in Table B under the heading of "exemplary substitutions," and as further described below in reference to amino acid side chain classes. Amino acid substitutions can be introduced into an antibody of interest and the products screened for a desired activity, e.g., retained / improved antigen binding, decreased immunogenicity, or improved ADCC or CDC.

[0610] Table B. Substitution of amino acids

[0611] According to common practice, amino acids can be grouped as follows:

[0612] (1) hydrophobic: Norleucine, Met, Ala, Val, Leu, He;

[0613] (2) neutral, hydrophilic: Cys, Ser, Thr, Asn, Gin;

[0614] (3) acidic: Asp, Glu;

[0615] (4) basic: His, Lys, Arg;

[0616] (5) residues that influence chain orientation: Gly, Pro;

[0617] (6) aromatic: Trp, Tyr, Phe.

[0618] Non-conservative substitutions will require an exchange of a member of one of these classes for a member from another class.

[0619] One type of substitutional variant involves substituting one or more amino acids in a CDR of a parent antibody (e.g., a humanized or human antibody). Generally, the resulting variant(s) selected for further study will have some alterations (e.g., improvements) in certain biological properties (e.g., increased affinity, reduced immunogenicity) relative to the parent antibody and / or will have substantially retained certain biological properties of the parent antibody. An exemplary substitutional variant is an affinity matured antibody, which can be conveniently generated, e.g., using phage display-based affinity maturation techniques such as those described herein. Briefly, one or more CDR residues are mutated, and the variant antibodies displayed on phage and screened for a particular biological activity (e.g., binding affinity). Changes (e.g., substitutions) can be made to a CDR, e.g., to improve antibody affinity. Such changes can be made, e.g., to CDR "hotspot" residues, i.e., residues encoded by codons that undergo mutation at high frequency during the somatic maturation process, and / or residues that contact antigen, while the resulting variant VHand / or VLis tested for binding affinity. In some embodiments of affinity maturation, diversity is introduced into the variable genes selected for maturation by any of a variety of methods (e.g., error-prone PCR, chain shuffling, or oligonucleotide-directed mutagenesis). Secondary libraries are then created. The libraries are then screened to identify any antibody variants having the desired affinity. Another method of introducing diversity involves CDR-directed approaches, in which several CDR residues (e.g., 4-6 residues at a time) are randomized. CDR residues involved in antigen binding can be specifically identified, e.g., using alanine scanning mutagenesis or modeling. In particular, HCDR3 and LCDR3 are often targeted.

[0620] In some embodiments, substitutions, insertions, or deletions can occur within one or more CDRs so long as such changes do not substantially reduce the ability of the antibody to bind antigen. For example, conservative alterations (e.g., conservative substitutions as provided herein) that do not substantially reduce binding affinity can be made to a CDR. Such alterations can be outside of antigen contacting residues in a CDR. In certain embodiments of the variant VHand VLsequences provided above, each CDR is unaltered, or contains no more than 1, 2, or 3 amino acid substitutions.

[0621] One method for identifying residues or regions in an antibody that can serve as targets for mutagenesis is called "alanine scanning mutagenesis" In this approach, one or more residues or sets of residues (e.g., charged residues such as Arg, Asp, His, Lys, and Glu) are identified and replaced with neutral or negatively charged amino acids (e.g., Ala or polyalanine) to determine whether the interaction of the antibody with antigen is affected. Further substitutions can be introduced at the amino acid positions that display functional sensitivity to the initial substitutions. Additionally, contact points between the antibody and antigen can be identified by studying crystals structures of antigen-antibody complexes. These contact residues and neighboring residues can be targeted or eliminated as candidates for substitution. Variants can be screened to determine whether they contain the desired properties.

[0622] Amino acid sequence insertions include amino- and / or carboxyl-terminal fusions ranging in length from one residue to polypeptides containing a hundred or more residues, as well as intrasequence insertions of single or multiple amino acid residues. Examples of terminal insertions include an antibody with an N-terminal methionyl residue. Other insertional variants of the antibody molecule include the fusion to the N- or C-terminus of the antibody to an enzyme or a polypeptide which increases the serum half-life of the antibody.

[0623] Recombinant methods

[0624] Anti-B7-H3 antibodies can be produced using recombinant methods. For these methods, one or more isolated nucleic acids encoding an anti-B7-H3 antibody are provided.

[0625] In some embodiments, the present disclosure provides an isolated nucleic acid encoding an anti-B7-H3 antibody as previously described. Such a nucleic acid can be provided as a separate nucleic acid encoding any of the polypeptide chains described previously. In some embodiments, the present disclosure provides one or more vectors (e.g., expression vectors) comprising such a nucleic acid. In some embodiments, the present disclosure provides a host cell comprising such a nucleic acid. In some embodiments, a method of producing a polypeptide or fusion protein is provided, wherein the method comprises culturing a host cell comprising a nucleic acid encoding the polypeptide or fusion protein, under conditions suitable for expression, as provided above, and optionally recovering the anti-B7-H3 antibody from the host cell (or host cell culture medium).

[0626] For recombinant production of an anti-B7-H3 antibody, nucleic acids encoding the protein are isolated and inserted into one or more vectors for further cloning and / or expression in a host cell. Such nucleic acids can be readily isolated and sequenced using conventional procedures, or produced by recombinant methods or obtained through chemical synthesis.

[0627] Suitable host cells for cloning or expression of vector encoding anti-B7-H3 antibodies include prokaryotic or eukaryotic cells described herein. For example, production in bacteria is possible, particularly when glycosylation and Fc effector function are not needed. After expression, the antibody can be isolated from the bacterial cell paste in a soluble fraction, and can be further purified.

[0628] In addition to prokaryotes, eukaryotic microorganisms, such as filamentous fungi or yeasts, are also suitable cloning or expression hosts for vectors encoding fusion proteins, including fungal and yeast strains. Suitable host cells for expression of fusion proteins can also be derived from multicellular organisms (invertebrates and vertebrates); examples of invertebrate cells include plant and insect cells. Numerous baculoviral strains have been identified which can be used in combination with insect cells, particularly for transfection of Spodoptera frugiperda cells; plant cell cultures can also be utilized as hosts, for example, US5959177, US6040498, US6420548, US7125978, and US6417429; vertebrate cells can also be used as hosts, for example, mammalian cell lines adapted to grow in suspension cell culture. Other examples of appropriate mammalian host cell lines are monkey kidney CVl line (COS-7) transformed by SV40 (COS-7); human embryonic kidney line (293 or 293T cells); baby hamster kidney cells (BHK); mouse Sertoli cells (TM4 cells); monkey kidney cells (CVl); African green monkey kidney cells (VERO-76); human cervical carcinoma cells (HELA); canine kidney cells (MDCK); buffalo rat liver cells (BRL 3A); human lung cells (W138); human liver cells (Hep G2); mouse mammary tumor (MMT 060562); TRI cells; MRC 5 cells; and FS4 cells. Other suitable mammalian host cell lines include Chinese hamster ovary (CHO) cells, including DHFR- CHO cells, and myeloma cell lines such as Y0, NS0 and Sp2 / 0.

[0629] Assays

[0630] The anti-B7-H3 antibodies, anti-B7-H3 antibody drug conjugates provided herein can be identified, screened, or characterized for their physical / chemical characteristics and / or biological activities by a variety of assays known in the art. In some embodiments, the anti-B7-H3 antibodies, anti-B7-H3 antibody drug conjugates of the disclosure are tested for activity, e.g., by known methods such as ELISA, Western blotting, etc.

[0631] Methods of treatment and routes of administration

[0632] Any of the anti-B7-H3 antibodies, anti-B7-H3 antibody drug conjugates provided by the present disclosure can be used in a method of treatment. In some embodiments, the use of an anti-B7-H3 antibody, anti-B7-H3 antibody drug conjugate provided by the present disclosure in the manufacture or preparation of a medicament. In some embodiments, the disease is a B7-H3 associated disease or disorder. In some embodiments, the B7-H3 associated disease or disorder is a tumor.

[0633] In some embodiments, a pharmaceutical composition comprising the anti-B7-H3 antibody, anti-B7-H3 antibody drug conjugate is provided, e.g., for any of the above pharmaceutical uses or methods of treatment. In some embodiments, the pharmaceutical composition comprises any of the anti-B7-H3 antibodies provided herein and a pharmaceutically acceptable carrier. In some embodiments, the pharmaceutical composition further comprises at least one additional therapeutic agent.

[0634] The anti-B7-H3 antibodies, anti-B7-H3 antibody drug conjugates of the present disclosure can be used alone or in combination with other agents for treatment. For example, the antibodies of the present disclosure can be co-administered with at least one additional therapeutic agent.

[0635] The anti-B7-H3 antibodies, anti-B7-H3 antibody drug conjugates of the present disclosure (and any additional therapeutic agents) can be administered by any appropriate means, including parenterally, intrapulmonary, and intranasally, and, if local treatment is required, intralesionally. Parenteral infusions include intramuscular, intravenous, intraarterial, intraperitoneal, or subcutaneous administration. Dosing can be by any appropriate route, for example, by injection, such as intravenous or subcutaneous injection, depending in part on whether the administration is short term or long term. A variety of dosing schedules are contemplated herein, including, but not limited to, single or multiple administrations at multiple time points, bolus administration, and pulse infusion.

[0636] The anti-B7-H3 antibodies, anti-B7-H3 antibody drug conjugates of the present disclosure will be formulated, dosed, and administered in a fashion consistent with good medical practice. Factors for consideration in this context include the particular disorder being treated, the particular mammal being treated, the clinical condition of the individual patient, the cause of the disorder, the site of delivery of the agent, the method of administration, the scheduling of administration, and other factors known to medical practitioners. The anti-B7-H3 antibodies, anti-B7-H3 antibody drug conjugates can be formulated with or without carriers and / or diluents and can be formulated in any manner suitable for the intended use.

[0637] For the prevention or treatment of disease, the appropriate dosage of an anti-B7-H3 antibody, anti-B7-H3 antibody drug conjugate of the present disclosure, when used alone or in combination with one or more other additional therapeutic agents, will depend on the type of disease to be treated, the type of treatment molecule, the severity and course of the disease, whether the purpose is preventive or therapeutic, the previous therapy, the patient's clinical history and response to the treatment molecule, and the judgment of the treating physician. The treatment molecule is appropriately administered to the patient at one time or over a series of treatments.

[0638] Articles of manufacture

[0639] In another aspect of the present disclosure, an article of manufacture containing materials useful for the treatment, prevention and / or diagnosis of the disorders described above is provided. The article of manufacture contains a container and a label or package insert on or associated with the container. Suitable containers include, for example, bottles, vials, syringes, IV solution bags, etc. The containers can be formed from a variety of materials such as glass or plastic. The container holds a composition which is effective for treating, preventing and / or diagnosing the condition and can have a sterile access port (for example the container can be an intravenous solution bag or a vial having a stopper pierceable by a hypodermic injection needle). At least one active agent in the composition is an anti-B7-H3 antibody, anti-B7-H3 antibody drug conjugate of the present disclosure. The label or package insert indicates that the composition is used for treating the condition of choice. Furthermore, the article of manufacture can further comprise: (a) a first container with a composition contained therein, wherein the composition comprises an anti-B7-H3 antibody, anti-B7-H3 antibody drug conjugate of the present disclosure; and (b) a second container with a composition contained therein, wherein the composition comprises a further therapeutic agent or other therapeutic agent. The article of manufacture in this embodiment of the present disclosure can further comprise a package insert indicating that the compositions can be used to treat the particular condition. Alternatively, or additionally, the article of manufacture can further comprise a second (or third) container comprising a pharmaceutically-acceptable buffer, which can be positioned in a thermally insulated container or in a cooler. From a commercial and user standpoint, it can be advantageous to present the therapeutic agent in a composition containing a pharmaceutically-acceptable buffer. It can further include other materials desirable from a commercial and user standpoint, including other buffers, diluents, filters, needles, and syringes.

[0640] Examples

[0641] The present disclosure is further described by the following examples and test examples, which do not limit the scope of the present disclosure. Methods for experiments not otherwise specifically noted in the examples and test examples of the present disclosure are generally performed according to conventional methods, such as those described in Current Protocols in Immunology, John Wiley & Sons, Inc., New York, NY, 1994; or as recommended by the manufacturer of the materials or products used. Reagents not specifically noted for their source are commercially available and are conventional.

[0642] Example 1: Preparation of B7-H3 antigen, control antibody

[0643] 1.1 B7-H3 antigen preparation

[0644] Human B7-H3-4Ig, monkey B7-H3-4Ig extracellular domain (ECD) were fused to different tags such as His or hFc, respectively cloned into pTT5 vector (Biovector, CAT#102762), transiently expressed in HEK 293 cells, purified to obtain antigen and detection protein for subsequent antibody screening and identification. The relevant protein amino acid sequences are as follows:

[0645] > Human B7-H3-4Ig (ECD)-hFc

[0646] > Monkey B7-H3-4Ig (ECD)-hFc

[0647] > Monkey B7-H3-4Ig (ECD)-His

[0648] Note: The background part of the undercoat is the extracellular domain (ECD) of the protein.

[0649] 1.2 Preparation of control antibodies

[0650] The positive control antibody sequence used in the present disclosure is derived from the antibody part of DS7300 disclosed in WHO Drug Information, Vol. 35, No. 4, 2021 (referred to as Ab1 in the present disclosure), and the heavy chain and light chain of the control antibody are synthesized by gene synthesis into the pTT5 vector. After plasmid extraction, transiently transfect into HEK293 cells for expression, centrifugal collection of supernatant, purification to obtain positive control antibody Ab1.

[0651] > Heavy chain of Ab1

[0652] > Light chain of Ab1

[0653] The VH / VL sequence of the negative control antibody Isotype used in the present disclosure is from patent US6114143A, and the full-length sequence is as follows:

[0654] > Isotype heavy chain:

[0655] > Isotype light chain:

[0656] In some embodiments, the heavy chain variable region and the light chain variable region of the negative control antibody Isotype are recombined with a human IgGl heavy chain constant region (hlgGl-AA, comprising L234A and L235A amino acid mutations, numbering according to EU index) and a human kappa light chain constant region, respectively, to obtain the negative control antibody Isotype-AA.

[0657] >hlgGl-AA

[0658] >Isotype-AA heavy chain:

[0659] >Isotype-AA light chain: identical to SEQ ID NO: 7.

[0660] Note: In the above sequences, the underlined part is the antibody variable region sequence, and the rest is the antibody constant region.

[0661] 1.3 Purification of antigens and control antibodies

[0662] 1.3.1 Purification procedure of recombinant proteins with His tag

[0663] The cell expression supernatant sample was centrifuged at high speed to remove impurities, and the buffer was replaced with PBS, and imidazole was added to a final concentration of 5 mM. The nickel column was equilibrated with PBS solution containing 5 mM imidazole, and washed with 2-5 column volumes. The replaced cell supernatant sample was loaded onto the Ni Sepharose excel column (GE, 17-3712-02). The column was washed with PBS containing 5 mM imidazole until the A280 reading dropped to the baseline. Then the column was washed with PBS + 10 mM imidazole to remove non-specifically bound impurities, and the effluent was collected. The target protein was eluted with PBS solution containing 300 mM imidazole, and the elution peak was collected. The collected eluate was concentrated and further purified by gel chromatography Superdex 200 (GE, 28-9893-35) with PBS as the mobile phase. The aggregate peak was removed, and the elution peak was collected. The obtained protein was identified as correct by electrophoresis, peptide mapping, and LC-MS, and then aliquoted for use.

[0664] 1.3.2 Purification procedure of recombinant proteins with Fc tag and control antibodies

[0665] The cell expression supernatant sample was centrifuged at high speed to remove impurities, and the supernatant was subjected to MabSelect Sure (GE, 17-5438-01) affinity chromatography. The MabSelect Sure chromatography column was first regenerated with 0.2M NaOH, then washed with pure water and equilibrated with PBS. After the supernatant was bound, PBS was used for washing until the A280 reading decreased to the baseline. The target protein was eluted at pH 3.5 with 0.1M acetic acid buffer, and neutralized with 1M Tris-HCl. After the eluted sample was appropriately concentrated, it was further purified by gel chromatography Superdex200 (GE, 28-9893-35) equilibrated with PBS, and the target protein was collected in the receiving tube and concentrated to an appropriate concentration.

[0666] Example 2: Preparation of mouse anti-human B7-H3 monoclonal antibody

[0667] 2.1 Immunization

[0668] Anti-B7-H3 antibodies were produced by immunizing mice. SJL / J white mice were used in the experiment, female, 6-8 weeks old (Shanghai Sulei Experimental Animal Co., Ltd., Animal Production License No.: SCXK (Shanghai) 2022-0004). Rearing environment: SPF level. After the mice were purchased, they were raised in the laboratory environment for 1 week, with 12 / 12 hour light / dark cycle adjustment, temperature 20-25°C; humidity 40-60%. The mice that had adapted to the environment were immunized according to the following scheme.

[0669] Immunization scheme 1: This immunization scheme used the protein antigen human B7-H3-4Ig (ECD)-hFc to immunize SJL / J mice. The antigen was alternately immunized with Gold Adjuvant (Sigma Cat No. T2684) and Thermo Alum (Thermo Cat No. 77161) adjuvant. The ratio of antigen to Thermo Gold Adjuvant was 1:1, and after complete emulsification, the mice were immunized; the ratio of antigen to Thermo The ratio of Alum is 3:1, and the mice are immunized after oscillation and mixing. The amount of protein antigen used for the first immunization of mice is 50 μg per mouse, and the amount of protein antigen used for subsequent regular immunization is 25 μg per mouse per time. The amount of protein antigen used for the pre-fusion booster immunization is 50 μg per mouse per time. The immunization frequency of mice is once every two weeks, and the antibody titer in the serum of mice is determined by blood sampling 7-10 days after each immunization from the second immunization. After the fourth immunization, the antibody titer in the serum of mice is determined by ELISA method, and the mice with high antibody titer and titer tending to platform in the serum are selected for spleen cell fusion. The antigen solution prepared by physiological saline and protein antigen (human B7-H3-4Ig (ECD)-hFc) is injected intraperitoneally (i.p.) for booster immunization three days before the spleen cell fusion.

[0670] Immunization scheme 2: SJL / J mice are immunized with protein antigens human B7-H3-4Ig (ECD)-hFc and monkey B7-H3-4Ig (ECD)-hFc alternately. The antigens are used alternately Gold Adjuvant (Sigma Cat No. T2684) and Thermo Alum (Thermo Cat No. 77161) adjuvant for immunization. The antigen is mixed with the adjuvant The ratio of Gold Adjuvant is 1:1, and the mice are immunized after complete emulsification; the antigen is mixed with the adjuvant Thermo The ratio of Alum is 3:1, and the mice are immunized after oscillation and mixing. The amount of protein antigen used for the first immunization of mice is 50 μg per mouse, and the amount of protein antigen used for subsequent regular immunization is 25 μg per mouse per time. The amount of protein antigen used for the pre-fusion booster immunization is 50 μg per mouse per time. The immunization frequency of mice is once every two weeks, and the antibody titer in the serum of mice is determined by blood sampling 7-10 days after each immunization from the second immunization. After the sixth immunization, the antibody titer in the serum of mice is determined by ELISA method, and the mice with high antibody titer and titer tending to platform in the serum are selected for spleen cell fusion. The antigen solution prepared by physiological saline and protein antigen (human B7-H3-4Ig (ECD)-hFc) is injected intraperitoneally (i.p.) for booster immunization three days before the spleen cell fusion.

[0671] 2.2 Spleen cell fusion

[0672] The spleen lymphocytes are fused with myeloma cells Sp2 / 0-Ag14 (ATCC CRL-8287 TM ) to obtain hybridoma cells by using the optimized electrofusion method.

[0673] The fused hybridoma cells are counted according to the spleen cell counting results, and the cells with a concentration of 3×105 / mL-7 x 10 5 / mL density resuspended in complete medium (IMDM medium with 20% FBS, 1 x HAT, 1 x OPI) and seeded in 96-well plates at 150 μL / well. After 4-5 days incubation at 37 °C, 5% CO2, the supernatant was removed and replaced with complete medium (IMDM medium with 20% FBS, 1 x HT and 1 x OPI) containing HT at 200 μL / well. The cells were incubated at 37 °C, 5% CO2 for 3-4 days before testing.

[0674] 2.3 Hybridoma cell screening and antibody sequence determination

[0675] Hybridoma supernatant was tested for binding to NCI-H358 human lung cancer cells (ATCC: CRL-580) and monkey B7-H3-4Ig(ECD)-His according to the growth density of the hybridoma cells.

[0676] NCI-H358 human lung cancer cell binding was screened by DELFIA method. Cells were plated at 1 x 10 5 / well and 40 μL of hybridoma supernatant was added and mixed by pipetting. The plate was incubated at 4 °C for 1 hour in the dark. The plate was washed twice with 1% BSA and 40 μL of secondary antibody Eu-N1-Anti-mouse IgG (PerkinElmer, 3101735) was added and mixed by pipetting. The plate was incubated at 4 °C for 30 minutes in the dark. The plate was washed twice with 1% BSA and 100 μL of DELFIA Enhancer (Revvity, 749717) was added and mixed by pipetting. The plate was incubated at 4 °C for 30 minutes in the dark. HTRF readings were taken and clones with readings comparable to or higher than the control antibody were selected.

[0677] Monkey cross was also retained when screening the clones. 100 μL / well of 1 μg / mL monkey B7-H3-4Ig(ECD)-His antigen was coated at 4 °C overnight. After washing three times with PBST, the plate was blocked with 5% milk at 37 °C for 3 hours. After washing three times with PBST, 40 μL of hybridoma supernatant was added and incubated at 37 °C for 1 hour. After washing three times, 100 μL / well of HRP Conjugated Goat Anti-mouse IgG (H+L) (Jackson) was added and incubated at 37 °C for 1 hour. After washing three times with PBST, the plate was dried and 100 μL / well of TMB was added. Color development was stopped after 5 minutes by adding an equal volume of 2M H2SO4. The OD450 absorbance value was read on a microplate reader and clones with readings five times higher than the negative control were selected.

[0678] The final selected clone can have good binding to NCI-H358 human lung cancer cells and can retain cross-binding to monkeys. In addition, the hybridoma cells are timely frozen, expanded, preserved, subcloned and single cell cloned. Through the above experimental screening, 3 hybridoma clones with excellent performance are obtained: mAb67, mAb77 and mAb127.

[0679] The hybridoma clone is expanded and cultured, RNA is extracted, and mouse-IgG degenerate primers are used for reverse transcription amplification (RT-PCR), and finally the variable region sequence of the antibody is obtained.

[0680] Table 1. CDR sequences of murine antibodies

[0681] >mAb67 heavy chain variable region:

[0682] >mAb67 light chain variable region:

[0683] >mAb127 heavy chain variable region:

[0684] >mAb127 light chain variable region:

[0685] >mAb77 heavy chain variable region:

[0686] >mAb77 light chain variable region:

[0687] Note: The amino acid residues of the CDR of the murine antibody are determined by the Kabat numbering system and marked with a hatched background.

[0688] The heavy chain variable region and the light chain variable region of the murine antibody are respectively cloned into the pTT5 vector plasmid containing the human IgG1 heavy chain constant region (SEQ ID NO: 24) and the human kappa light chain constant region (SEQ ID NO: 25), and then transfected into HEK293 cells to obtain chimeric antibodies, and the relevant sequences are as follows:

[0689] >Human IgG1 heavy chain constant region

[0690] >Human kappa light chain constant region

[0691] >CHI67 heavy chain

[0692] >CHI67 light chain

[0693] >CHI127 heavy chain

[0694] >CHI127 light chain

[0695] >CHI77 heavy chain

[0696] >CHI77 light chain

[0697] Note: Hatched background in the sequence is the variable region of the antibody, and the rest is the constant region.

[0698] Example 3: Humanization of murine anti-B7-H3 antibodies

[0699] 3.1 Humanization of anti-B7-H3 antibody mAb67

[0700] By aligning with the IMGT human antibody heavy and light chain variable region germline gene database through MOE software, the heavy chain variable region and light chain variable region germline genes with high homology to mAb67 were selected as templates, and the CDRs of mAb67 were transplanted into the corresponding human templates to form the variable region sequence in the order of FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4. Exemplarily, the CDR amino acid residues in the following specific examples are determined and annotated by the Kabat numbering system.

[0701] The FR1, FR2, FR3 of IGKV2-29*02 and the FR4 of IGKJ2*01, i.e., FGQGTKLEIK (SEQ ID NO: 103), were selected as the light chain framework region template for the humanized antibody of mAb67; the FR1, FR2, FR3 of IGHV1-46*01 and the FR4 of IGHJ6*01, i.e., WGQGTTVTVSS (SEQ ID NO: 104), were selected as the heavy chain framework region template. Optionally, the amino acid residues at positions 2, 28, 30 and / or 45 of the light chain variable region of the humanized antibody are substituted; and / or the amino acid residues at positions 1, 40, 54, 69, 71, 73, 78, 80 and / or 93 of the heavy chain variable region of the humanized antibody are substituted.

[0702] Table 2. Humanized antibodies of mAb67

[0703] Table 3. CDRs of humanized antibodies of mAb67

[0704] >hu67VH1

[0705] >hu67VH2

[0706] >hu67VH3

[0707] >hu67VH4

[0708] >hu67VH5

[0709] >hu67VH6

[0710] >hu67VH7

[0711] >hu67VH8

[0712] >hu67VH9

[0713] >hu67VL1

[0714] >hu67VL2

[0715] >hu67VL3

[0716] >hu67VL4

[0717] >hu67VL5

[0718] >hu67VL6

[0719] Note: In the above sequences, the order is FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4; the underlined background is CDR determined according to the Kabat numbering system; the italicized and bolded part is the mutation site; the rest is FR.

[0720] The heavy chain variable region and the light chain variable region of the humanized antibody were recombined with human IgG1 heavy chain constant region and human kappa light chain constant region, respectively, to obtain the humanized antibodies shown in the following table.

[0721] Table 4. Humanized antibodies of mAb 67

[0722] Note: hu67H1L1 means that the antibody comprises the heavy chain variable region hu67VH1 (SEQ ID NO: 33) and the light chain variable region hu67VL1 (SEQ ID NO: 42), and its heavy chain constant region is human IgG1 heavy chain constant region (SEQ ID NO: 24), the light chain constant region is human kappa light chain constant region (SEQ ID NO: 25), and the other is similar. The above-mentioned antibodies are respectively genetically synthesized, expressed, and purified.

[0723] The heavy chain and light chain amino acid sequences of exemplary humanized antibodies are as follows:

[0724] >hu67H1L1, hu67H1L2, hu67H1L3, hu67H1L4, hu67H1L5 heavy chain

[0725] >hu67H2L1, hu67H2L2, hu67H2L3 heavy chain

[0726] >hu67H3L1, hu67H3L2, hu67H3L3 heavy chain

[0727] >hu67H4L1, hu67H4L2, hu67H4L3 heavy chain

[0728] >hu67H5L1, hu67H5L2, hu67H5L3 heavy chain

[0729] >hu67H6L1, hu67H6L2, hu67H6L3 heavy chain

[0730] >hu67H7L1, hu67H7L2, hu67H7L3 heavy chain

[0731] >hu67H8L1, hu67H8L4, hu67H8L5, hu67H8L6 heavy chain

[0732] >hu67H9L1, hu67H9L4, hu67H9L5 heavy chain

[0733] >hu67H1L1, hu67H2L1, hu67H3L1, hu67H4L1, hu67H5L1, hu67H6L1, hu67H7L1, hu67H8L1, hu67H9L1 light chain

[0734] Light chain of hu67H1L2, hu67H2L2, hu67H3L2, hu67H4L2, hu67H5L2, hu67H6L2, hu67H7L2

[0735] Light chain of hu67H1L3, hu67H2L3, hu67H3L3, hu67H4L3, hu67H5L3, hu67H6L3, hu67H7L3

[0736] Light chain of hu67H1L4, hu67H8L4, hu67H9L4

[0737] Light chain of hu67H1L5, hu67H8L5, hu67H9L5

[0738] Light chain of hu67H8L6

[0739] Note: In the above sequences, the underlined background is the antibody variable region, and the rest is the antibody constant region.

[0740] In some embodiments, the heavy chain variable region and the light chain variable region of the humanized antibody are recombined with a human IgG1 heavy chain constant region (hIgG1-AA, comprising L234A and L235A amino acid mutations, numbering according to the EU index) and a human kappa light chain constant region, respectively, to obtain the humanized antibody.

[0741] The heavy chain and light chain amino acid sequences of exemplary humanized antibodies are as follows:

[0742] Heavy chain of hu67H8L6-AA

[0743] Light chain of hu67H8L6-AA: same as SEQ ID NO: 62

[0744] 3.2 Humanization of anti-B7-H3 antibody mAb127

[0745] By MOE software, the heavy chain variable region and the light chain variable region germline genes with high homology to mAb127 are selected as templates by alignment with the IMGT human antibody heavy and light chain variable region germline gene database, and the CDRs of mAb127 are transplanted into the corresponding human templates, respectively, to form the variable region sequence in the order of FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4. Exemplarily, the CDR amino acid residues in the following specific examples are determined and annotated by the Kabat numbering system.

[0746] The humanized antibody for mAb127 was prepared using FR1, FR2, and FR3 of IGKV1-39*01 and FR4 of IGKJ4*01, i.e., FGGGTKVEIK (SEQ ID NO: 106), as the template for the light chain framework region; and FR1, FR2, and FR3 of IGHV1-69*02 and FR4 of IGHJ1*01, i.e., WGQGTLVTVSS (SEQ ID NO: 107), as the template for the heavy chain framework region. Optionally, amino acid residues at positions 41, 42, 43, 44, 56, and / or 71 of the light chain variable region of the humanized antibody were substituted; and / or amino acid residues at positions 1, 27, 37, 40, and / or 94 of the heavy chain variable region of the humanized antibody were substituted.

[0747] Table 5. Humanized antibodies against mAb127

[0748] Table 6. CDRs of humanized antibodies against mAb127

[0749] >hu127VH1

[0750] >hu127VH2

[0751] >hu127VH3

[0752] >hu127VH4

[0753] >hu127VH5

[0754] >hu127VH6

[0755] >hu127VL1

[0756] >hu127VL2

[0757] >hu127VL3

[0758] >hu127VL4

[0759] >hu127VL5

[0760] >hu127VL6

[0761] Note: In the above sequences, the order is FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4; the underlined background is CDR determined according to the Kabat numbering system; the italicized and bolded part is the mutation site; the rest is FR.

[0762] The heavy chain variable region and the light chain variable region of the humanized antibody were recombined with the human IgG1 heavy chain constant region and the human kappa light chain constant region, respectively, to obtain the humanized antibodies shown in the following table.

[0763] Table 7. Humanized antibodies of mAb 127

[0764] Note: hu127H1L1 indicates that the antibody comprises the heavy chain variable region hu127VH1 (SEQ ID NO: 64) and the light chain variable region hu127VL1 (SEQ ID NO: 70), and its heavy chain constant region is the human IgG1 heavy chain constant region (SEQ ID NO: 24), the light chain constant region is the human kappa light chain constant region (SEQ ID NO: 25), and the others are analogously deduced. The above-mentioned antibodies were respectively genetically synthesized, expressed, and purified.

[0765] The heavy chain and light chain amino acid sequences of exemplary humanized antibodies are as follows:

[0766] >Heavy chain of hu127H1L1, hu127H1L2, hu127H1L3, hu127H1L4, hu127H1L5, hu127H1L6

[0767] >Heavy chain of hu127H2L1, hu127H2L2, hu127H2L3, hu127H2L4, hu127H2L5, hu127H2L6

[0768] >Heavy chain of hu127H3L1, hu127H3L2, hu127H3L3, hu127H3L4, hu127H3L5, hu127H3L6

[0769] >Heavy chain of hu127H4L1, hu127H4L2, hu127H4L3, hu127H4L4, hu127H4L5, hu127H4L6

[0770] Heavy chains of hu127H5L1, hu127H5L2, hu127H5L3, hu127H5L4, hu127H5L5, hu127H5L6

[0771] Heavy chains of hu127H6L1, hu127H6L2, hu127H6L3, hu127H6L4, hu127H6L5, hu127H6L6

[0772] Light chains of hu127H1L1, hu127H2L1, hu127H3L1, hu127H4L1, hu127H5L1, hu127H6L1

[0773] Light chains of hu127H1L2, hu127H2L2, hu127H3L2, hu127H4L2, hu127H5L2, hu127H6L2

[0774] Light chains of hu127H1L3, hu127H2L3, hu127H3L3, hu127H4L3, hu127H5L3, hu127H6L3

[0775] Light chains of hu127H1L4, hu127H2L4, hu127H3L4, hu127H4L4, hu127H5L4, hu127H6L4

[0776] Light chains of hu127H1L5, hu127H2L5, hu127H3L5, hu127H4L5, hu127H5L5, hu127H6L5

[0777] Light chains of hu127H1L6, hu127H2L6, hu127H3L6, hu127H4L6, hu127H5L6, hu127H6L6

[0778] Note: In the above sequences, the underlined background is the variable region of the antibody, and the rest is the constant region of the antibody.

[0779] In some embodiments, the heavy chain variable region and the light chain variable region of the humanized antibody are recombined with a human IgG1 heavy chain constant region (hIgG1-AA, comprising L234A and L235A amino acid mutations, numbering according to the EU index) and a human kappa light chain constant region, respectively, to obtain the humanized antibody.

[0780] The heavy and light chain amino acid sequences of exemplary humanized antibodies are as follows:

[0781] >Heavy chain of hu127H3L2-AA

[0782] >Light chain of hu127H3L2-AA: identical to SEQ ID NO: 83

[0783] 3.3 Humanization of anti-B7-H3 antibody mAb77

[0784] By aligning with the IMGT human antibody heavy and light chain variable region germline gene database through MOE software, the heavy chain variable region and light chain variable region germline genes with high homology to mAb77 were selected as templates, and the CDRs of mAb77 were transplanted into the corresponding human templates to form the variable region sequence in the order of FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4. Exemplarily, the CDR amino acid residues in the following specific examples are determined and annotated by the Kabat numbering system.

[0785] The FR1, FR2, FR3 of IGKV2-28*01 and the FR4 of IGKJ4*01, i.e., FGGGTKVEIK (SEQ ID NO: 109), were selected as the light chain framework region template for the humanized antibody of mAb77 antibody; the FR1, FR2, FR3 of IGHV1-46*01 and the FR4 of IGHJ6*01, i.e., WGQGTTVTVSS (SEQ ID NO: 110), were selected as the heavy chain framework region template. Optionally, the amino acid residues at positions 27c, 30 and / or 56 of the light chain variable region of the humanized antibody are substituted; and / or the amino acid residues at positions 1, 38, 40, 58, 66, 69, 71, 76, 78, 82a and / or 83 of the heavy chain variable region of the humanized antibody are substituted.

[0786] Table 8. Humanized antibodies of mAb77

[0787] Table 9. CDRs of humanized antibodies of mAb77

[0788] >hu77VH1

[0789] >hu77VH2

[0790] >hu77VH3

[0791] >hu77VH4

[0792] >hu77VH5

[0793] >hu77VH6

[0794] >hu77VH7

[0795] >hu77VH8

[0796] >hu77VH9

[0797] >hu77VH10

[0798] >hu77VH11

[0799] >hu77VL1

[0800] >hu77VL2

[0801] >hu77VL3

[0802] Note: In the above sequences, the order is FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4; the underlined background is CDR determined according to the Kabat numbering system; the italicized and bolded part is the mutation site; the rest is FR.

[0803] The heavy chain variable region and the light chain variable region of the humanized antibody were recombined with the human IgG1 heavy chain constant region and the human kappa light chain constant region, respectively, to obtain the humanized antibody shown in the following table.

[0804] Table 10. Humanized antibodies of mAb77

[0805] The heavy chain and light chain amino acid sequences of the exemplary humanized antibodies are as follows:

[0806] >Heavy chain of hu77H1L1

[0807] >Heavy chain of hu77H2L1

[0808] >Heavy chain of hu77H3L1

[0809] Heavy chain of hu77H4L1

[0810] Heavy chain of hu77H5L1

[0811] Heavy chain of hu77H6L1

[0812] Heavy chain of hu77H7L1

[0813] Heavy chain of hu77H8L1

[0814] Heavy chain of hu77H9L1

[0815] Heavy chain of hu77H10L1

[0816] Heavy chain of hu77H11L1, hu77H11L2, hu77H11L3

[0817] Light chain of hu77H1L1, hu77H2L1, hu77H3L1, hu77H4L1, hu77H5L1, hu77H6L1, hu77H7L1, hu77H8L1, hu77H9L1, hu77H10L1, hu77H11L1

[0818] Light chain of hu77H11L2

[0819] Light chain of hu77H11L3

[0820] Note: In the above sequences, the underlined background is the variable region sequence of the antibody, and the rest is the constant region of the antibody.

[0821] In some embodiments, the heavy chain variable region and the light chain variable region of the humanized antibody are recombined with a human IgGl heavy chain constant region (hIgGl-AA, comprising L234A and L235A amino acid mutations, numbering according to the EU index) and a human kappa light chain constant region, respectively, to obtain the humanized antibody.

[0822] The heavy chain and light chain amino acid sequences of exemplary humanized antibodies are as follows:

[0823] Heavy chain of hu77H11L2-AA

[0824] Light chain of >hu77H11L2-AA: Same as SEQ ID NO: 141.

[0825] Example 4: Fabrication of ADC

[0826] The following general reaction formulas are applicable to the preparation of ADC-1 through ADC-5:

[0827] At 37°C, a prepared aqueous solution of tris(2-carboxyethyl)phosphonic acid hydrochloride (TCEP·HCl) (10 mM, 45.2 μL, 452 nmol) was added to the PBS buffered aqueous solution of antibody hu67H8L6-AA (pH=6.3, 0.05 M PBS buffered aqueous solution; 10.0 mg / ml, 2.77 ml, 192.4 nmol). The solution was placed in a water bath shaker and shaken at 37°C for 3 hours. The reaction was then stopped, and the reaction solution was cooled to 25°C.

[0828] Compound 9-A (2.0 mg, 1.86 μmol) was dissolved in 141 μL of dimethyl sulfoxide and added to the above reaction solution. The mixture was placed in a constant temperature shaker and shaken at 25 °C for 3 hours, after which the reaction was stopped. The reaction solution was desalted and purified by Sephadex G25 gel column chromatography (elution phase: 0.05 M PBS buffered aqueous solution at pH 6.3) to obtain a buffer of the title product ADC-1, which was stored at 4 °C.

[0829] The average number of drugs bound per antibody molecule was calculated by RP-HPLC: n = 4.06.

[0830] ADC-2

[0831] At 37°C, a prepared aqueous solution of tris(2-carboxyethyl)phosphonic acid hydrochloride (TCEP·HCl) (10 mM, 21.1 μL, 211 nmol) was added to the His-HOAc buffer solution of antibody hu77H11L2-AA (0.03 M His-HOAc buffer solution with pH = 6.3; 10.0 mg / ml, 1.33 ml, 91.1 nmol). The solution was placed in a water bath shaker and shaken at 37°C for 3 hours. The reaction was then stopped, and the reaction solution was cooled to 25°C. The pH was adjusted to 5.0 with dilute acetic acid aqueous solution.

[0832] Compound 9-A (0.99 mg, 922 nmol) was dissolved in 72 μL of dimethyl sulfoxide and added to the above reaction solution, which was placed in a constant temperature shaker and shaken at 25 °C for 3 hours to stop the reaction. The reaction solution was desalted and purified by a Sephadex G25 gel column (eluent: 0.03 M His-HOAc aqueous buffer solution, pH = 5.0) to obtain a buffer solution of the title product ADC-2, which was stored at 4 °C.

[0833] RP-HPLC calculated the average number of drug molecules bound per antibody molecule: n = 4.12.

[0834] ADC-3

[0835] To an aqueous solution of antibody Isotype-AA in PBS (0.05 M PBS aqueous buffer solution, pH = 6.3; 10.0 mg / mL, 0.62 mL, 42.7 nmol) was added a prepared aqueous solution of tris(2-carboxyethyl)phosphine hydrochloride (TCEP-HCl) (10 mM, 9.86 μL, 98.6 nmol) at 37 °C, which was placed in a water bath shaker and shaken at 37 °C for 3 hours to stop the reaction. The reaction solution was cooled to 25 °C using a water bath.

[0836] Compound 9-A (0.45 mg, 0.42 μmol) was dissolved in 31 μL of dimethyl sulfoxide and added to the above reaction solution, which was placed in a water bath shaker and shaken at 25 °C for 3 hours to stop the reaction. The reaction solution was desalted and purified by a Sephadex G25 gel column (eluent: 0.05 M PBS aqueous buffer solution, pH = 6.3) to obtain a buffer solution of the title product ADC-3, which was stored at 4 °C.

[0837] RP-HPLC calculated the average number of drug molecules bound per antibody molecule: n = 4.11.

[0838] ADC-4

[0839] To an aqueous solution of antibody hu127H3L2-AA in His-HOAc (0.03 M His-HOAc aqueous buffer solution, pH = 6.3; 10.0 mg / mL, 0.914 mL, 63.1 nmol) was added a prepared aqueous solution of tris(2-carboxyethyl)phosphine hydrochloride (TCEP-HCl) (10 mM, 14.5 μL, 145 nmol) at 37 °C, which was placed in a water bath shaker and shaken at 37 °C for 3 hours to stop the reaction. The reaction solution was cooled to 25 °C, and the pH was adjusted to 5.0 with dilute acetic acid aqueous solution.

[0840] Compound 9-A (0.54 mg, 505 nmol) was dissolved in 50 μL of dimethyl sulfoxide and added to the above reaction solution, which was placed in a constant temperature shaker and shaken at 25 °C for 3 hours to stop the reaction. The reaction solution was desalted and purified by a Sephadex G25 gel column (eluent: 0.03 M His-HOAc aqueous buffer solution, pH = 5.0) to obtain a buffer solution of the title product ADC-4, which was stored at 4 °C.

[0841] MS calculated average number of drug binding per molecule of antibody: n = 3.8.

[0842] ADC-5

[0843] To an aqueous His-HOAc buffer solution of antibody Isotype-AA (0.03 M His-HOAc aqueous buffer solution, pH = 6.3; 10.0 mg / mL, 1.31 mL, 90.6 nmol) was added a prepared aqueous solution of tris(2-carboxyethyl)phosphine hydrochloride (TCEP-HCl) (10 mM, 19.5 μL, 195 nmol) at 37 °C, which was placed in a water bath shaker and shaken at 37 °C for 3 hours to stop the reaction. The reaction solution was cooled to 25 °C using a water bath, and the pH was adjusted to 5.0 using dilute acetic acid aqueous solution.

[0844] Compound 9-A (0.78 mg, 0.725 μmol) was dissolved in 71 μL of dimethyl sulfoxide and added to the above reaction solution, which was placed in a water bath shaker and shaken at 25 °C for 3 hours to stop the reaction. The reaction solution was desalted and purified by a Sephadex G25 gel column (eluent: 0.03 M His-HOAc aqueous buffer solution, pH = 5.0) to obtain a buffer solution of the title product ADC-5, which was stored at 4 °C.

[0845] MS calculated average number of drug binding per molecule of antibody: n = 3.8.

[0846] Test Example

[0847] Test Example 1: FACS detection of cell level affinity of hu67 / 77 series humanized antibodies

[0848] Tumor cells NCI-H358 (human lung cancer cells, ATCC: CRL-580) expressing B7-H3 were prepared into 1 x 10 6100 μL / well of cell suspension was added to each well of a 96-well round-bottom plate (Corning, 3795). The plates were centrifuged at 300 g for 5 minutes, and the supernatant was removed. Different concentrations of the test antibody were added, 100 μL / well. The plates were incubated at 4°C in the dark for 1 hour. After washing three times by centrifugation at 300 g, the working concentration of APC anti-human IgG Fc (BioLegend, 3402) was added, and the plates were incubated at 4°C in the dark for 40 minutes. After washing three times by centrifugation at 300 g, the mean fluorescence intensity was measured using an Invitrogen flow cytometer, and the antibody binding Emax and EC50 were calculated. 50 Values. The results are shown in Table 11 and Figures 1A to 1C.

[0849] Table 11. Binding activity of humanized antibodies to B7-H3-expressing tumor cells

[0850] Note: / indicates no combination

[0851] The results showed that all of the above-mentioned humanized antibodies could bind to tumor cells expressing B7-H3.

[0852] Test Example 2: DELFIA Detection of Cellular Affinity of hu127 / 77 Series Humanized Antibodies

[0853] Cell-level affinity was detected using the DELFIA method. NCI-H358 tumor cells (human lung cancer cells, ATCC: CRL-580) expressing B7-H3 were prepared into 1×10⁻⁶ cells using buffer (1% BSA + pH 7.4 PBS). 6 100 μL / well of cell suspension was added to each well of a 96-well round-bottom plate (Corning, 3795). The plate was centrifuged at 300g for 5 minutes, and the supernatant was removed. Different concentrations of the test antibody were added, 100 μL / well. The plates were incubated at 4°C in the dark for 1 hour. After washing three times by centrifugation at 300g for 5 minutes, the secondary antibody Eu-N1-Anti-human IgG (PerkinElmer, 3030846) was added and the plate was resuspended by pipetting. The plate was incubated at 4°C in the dark for 30 minutes, washed twice with 1% BSA, and finally, 100 μL of LDELFIA enhancer (Revvity, 749717) was added to each well and the plate was incubated at 4°C for 30 minutes before measuring the HTRF reading. The results are shown in Table 12 and Figures 2A-2B.

[0854] Table 12. Binding activity of humanized antibodies to B7-H3-expressing tumor cells

[0855] The results showed that all of the above-mentioned humanized antibodies could bind to tumor cells expressing B7-H3.

[0856] Test Example 3: Biacore detection of affinity of anti-B7-H3 antibodies to human B7-H3-4lg antigen

[0857] The affinity of the chimeric and humanized antibodies of the present disclosure to human B7-H3-4lg antigen (ACRO: B7B-H52E7) was tested using a Biacore instrument. The method was as follows:

[0858] The antibodies were captured by affinity on a Protein A biosensor chip, and then the antigen molecules were flowed over the chip surface, and the binding and dissociation curves were obtained by real-time detection of the reaction signal using a Biacore 8K instrument. After each experimental cycle was completed, the biosensor chip was cleaned and regenerated with Glycine 1.5. The data fitting model used a 1:1 Model. The results are shown in Table 13.

[0859] Table 13. Affinity of anti-B7-H3 humanized antibodies to human B7-H3-4lg protein binding

[0860] The results show that the above-mentioned antibodies have good affinity to human B7-H3-4lg antigen.

[0861] Test Example 4: Detection of endocytosis activity of anti-B7-H3 antibodies

[0862] The endocytosis activity of the antibodies was evaluated using the Human Fabfluor-pH Red Antibody Labeling Dye (Sartorius, 4722) method. The Fabfluor-pH Red dye has almost no fluorescence under neutral pH conditions, and when it is endocytosed into cells in combination with the antibody, it will produce fluorescence in an acidic environment (excitation light: 640 nm, emission light: 664 nm). The endocytosis activity of the antibody was evaluated according to the change in fluorescence signal.

[0863] a. Cell plating: Collect NCI-H358 human lung cancer cells in the logarithmic growth phase, prepare a cell suspension with fresh cell culture medium containing 20% low IgG fetal bovine serum (Biosun, BS-0007-500), and add 3x10 4 cells / well / 50 μL to a 96-well cell culture plate (Corning, 3603) and incubate at 37°C in 5% carbon dioxide overnight;

[0864] b. Fabfluor-pH Red incubation with antibody: Prepare Fabfluor-pH Red (360 nM) at 4x concentration with serum-free medium. Prepare antibody (120 nM) at 4x concentration with serum-free medium, mix 60 pL Fabfluor-pH Red and 60 pL antibody at 1:1 volume, incubate at room temperature for 15 min;

[0865] c. Take 50 pL diluted antibody / Fabfluor-pH Red mixture to cell culture plate, incubate in incubator for 48 h, use Incucyte to detect fluorescence value in real time;

[0866] d. Fluorescence value detection: detect the area of phase cell (Phase area) and the area of red fluorescence (Red area) respectively, and calculate the ratio (%) of red fluorescence area (Red area) to phase cell area (Phase area);

[0867] e. Use Graphpad prism software to analyze data and draw the curve of fluorescence intensity over time.

[0868] The results of the curve of fluorescence intensity over time are shown in FIGS. 3A-3B.

[0869] The results show that hu67H8L6-AA, hu127H3L2, hu127H3L2-AA, hu77H11L2, hu77H11L2-AA all show better endocytosis activity than the positive control Ab1. At the same time, by comparing the endocytosis results of hu127H3L2 and hu127H3L2-AA and hu77H11L2 and hu77H11L2-AA, it can be seen that the L234A and L235A mutations in the constant region do not affect the endocytosis activity of the humanized antibodies in the present disclosure.

[0870] Test Example 5: In vitro cell killing activity detection of ADC

[0871] The 3D CTG method was used to evaluate the proliferation inhibition effect of ADC on 3D cultured tumor cells NCI-H358.

[0872] a. Cell plating: digest and collect cells, prepare cell suspension with fresh cell culture medium containing 10% FBS, add 200 cells / well / 36 pL to ultra-low adsorption 384-well sphere microplate (Corning, 3830), do not plate cells in columns 1 and 2, only add 36 pL of culture medium, centrifuge at 2000 rpm for 5 min, and incubate in a 5% carbon dioxide 37°C incubator overnight;

[0873] b. Gradient dilution: ADC-1, ADC-2, ADC-4 samples were prepared in PBS to 2.5 μΜ (10x concentration), ADC-3, ADC-5 samples were prepared in PBS to 10 μΜ (10x concentration). With this as the first concentration, 4-fold gradient dilution was performed with complete medium, a total of 10 concentration gradients. 4 μL / well was added to the cell culture plate, 5% carbon dioxide, 37°C, cultured for 6 days;

[0874] c. 3D CTG detection: 20 μL / well was added to the cell culture plate 3D Cell Viability Assay (Promega, G9683), room temperature for 30 min, Envision read chemiluminescence;

[0875] d. The experimental data was analyzed using Graphpad prism software, and the IC 50 value and Imax value were calculated according to the dose-response curve. Inhibition rate (%) = (Lum solvent control-Lum drug group) / (Lum solvent control-Lum blank control) x 100%.

[0876] Detailed results are shown in Table 14.

[0877] Table 14. In vitro cell killing activity of ADC

[0878] The results show that ADC-1, ADC-2, ADC-4 have good in vitro killing activity on tumor cells.

[0879] Although the above invention has been described in detail with the aid of the accompanying drawings and examples for the purpose of clarity, the description and examples should not be construed to limit the scope of the disclosure. The disclosures of all patents and scientific literature cited herein are expressly incorporated by reference in their entirety.

Claims

1. An anti-B7-H3 antibody comprising a heavy chain variable region and a light chain variable region, wherein, The heavy chain variable region comprises HCDR1, HCDR2 and HCDR3, and the light chain variable region comprises LCDR1, LCDR2 and LCDR3, wherein: (1) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 8, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 88, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 89, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 13; or (2) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 14, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 15, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 16, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 17, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 90, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 19; or (3) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 93, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 144, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 95, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 145, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 146, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 98; Preferably, (1) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 8, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 32 or 9, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 30, 11 or 31, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 13; or (2) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 14, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 15, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 16, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 17, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 18 or 63, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 19; or (3) the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 93, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 144, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 95, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 145, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 146, and the LCDR3 comprises the amino acid sequence of SEQ ID NO:

98. (3) HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 93, HCDR2 comprises the amino acid sequence of SEQ ID NO: 114 or 94, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 95, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 111, 96 or 113, LCDR2 comprises the amino acid sequence of SEQ ID NO: 112 or 97, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 98; More preferably, (1) HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 8, HCDR2 comprises the amino acid sequence of SEQ ID NO: 32, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 30, 11 or 31, LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 13; or HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 8, HCDR2 comprises the amino acid sequence of SEQ ID NO: 9, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 11, 30 or 31, LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 13; or (2) HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 14, HCDR2 comprises the amino acid sequence of SEQ ID NO: 15, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 16, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 17, LCDR2 comprises the amino acid sequence of SEQ ID NO: 18 or 63, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 19; or (3) HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 93, HCDR2 comprises the amino acid sequence of SEQ ID NO: 114, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 95, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 111 or 113, LCDR2 comprises the amino acid sequence of SEQ ID NO: 112, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 98; or (3) HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 93, HCDR2 comprises the amino acid sequence of SEQ ID NO: 114, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 95, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 111 or 113, LCDR2 comprises the amino acid sequence of SEQ ID NO: 112, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 98; or HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 93, HCDR2 comprises the amino acid sequence of SEQ ID NO: 94 or 114, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 95, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 96, LCDR2 comprises the amino acid sequence of SEQ ID NO: 97, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 98; Most preferably, (1) HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 8, HCDR2 comprises the amino acid sequence of SEQ ID NO: 32, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 10, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 30, LCDR2 comprises the amino acid sequence of SEQ ID NO: 12, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 13; or (2) HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 14, HCDR2 comprises the amino acid sequence of SEQ ID NO: 15, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 16, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 17, LCDR2 comprises the amino acid sequence of SEQ ID NO: 18, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 19; or (3) HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 93, HCDR2 comprises the amino acid sequence of SEQ ID NO: 114, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 95, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 111, LCDR2 comprises the amino acid sequence of SEQ ID NO: 112, and LCDR3 comprises the amino acid sequence of SEQ ID NO:

98.

2. The anti-B7-H3 antibody of claim 1, wherein the anti-B7-H3 antibody is a murine antibody, a chimeric antibody, a humanized antibody, or a fully human antibody. Preferably, the anti-B7-H3 antibody is a murine antibody, a chimeric antibody, or a humanized antibody. More preferably, the anti-B7-H3 antibody is a humanized antibody.

3. The anti-B7-H3 antibody of claim 1 or 2, wherein: (1) the heavy chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 40, 33, 41, 34, 35, 36, 37, 38, or 39, and the light chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 47, 42, 45, 46, 43, or 44; or the heavy chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 20, and the light chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 21; or (2) the heavy chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 66, 69, 64, 65, 67, or 68, and the light chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 71, 70, 72, 73, 74, or 75; or the heavy chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 22, and the light chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 23; or (3) the heavy chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 125, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124, and the light chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 127, 126, or 128; or the heavy chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 99, and the light chain variable region comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 100; Preferably, (1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, 33, 41, 34, 35, 36, 37, 38, or 39, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 47, 42, 45, 46, 43, or 44; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 20, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 21; or (2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 66, 69, 64, 65, 67, or 68, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 71, 70, 72, 73, 74, or 75; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 22, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 23; or (3) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 125, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 127, 126, or 128; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 99, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 100; More preferably, (1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, 33, 41, 34, 35, 36, 37, 38, or 39, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 47, 42, 45, 46, 43, or 44; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 20, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 21; or (2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 66, 69, 64, 65, 67, or 68, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 71, 70, 72, 73, 74, or 75; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 22, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 23; or (3) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 125, 115, 116, 117, 118, 119, 120, 121, 122, 123, or 124, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 127, 126, or 128; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 99, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 100; (1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 47; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 34, 35, 36, 37, 38, 39, 40, or 41, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 42; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 34, 35, 36, 37, 38, or 39, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 43; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 34, 35, 36, 37, 38, or 39, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 44; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 40, or 41, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 45; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 33, 40, or 41, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 46; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 20, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 21; or (2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 66, 64, 65, 67, 68, or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 71; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 69, 64, 65, 66, 67, or 68, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 70; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 64, 65, 66, 67, 68, or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 72; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 64, 65, 66, 67, 68, or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 73; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 64, 65, 66, 67, 68, or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 74; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 64, 65, 66, 67, 68, or 69, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 75; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 22, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 23; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 22, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 23; or (3) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 125, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 127 or 128; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, or 125, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 126; or the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 99, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 100; most preferably, (1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 47; or (2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 66, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 71; or (3) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 125, and the light chain variable region comprises the amino acid sequence of SEQ ID NO:

127.

4. The anti-B7-H3 antibody of any one of claims 1 to 3, wherein the antibody comprises a heavy chain constant region and a light chain constant region; preferably, the heavy chain constant region is a heavy chain constant region of human IgGl, IgG2, IgG3, IgG4, or a variant thereof, and the light chain constant region is a light chain constant region of human kappa chain, lambda chain, or a variant thereof; more preferably, the heavy chain constant region is a human IgGl heavy chain constant region or a variant thereof, and the light chain constant region is a human kappa light chain constant region or a variant thereof; most preferably, the heavy chain constant region comprises the amino acid sequence of SEQ ID NO: 24 or 91, and the light chain constant region comprises the amino acid sequence of SEQ ID NO:

25.

5. The anti-B7-H3 antibody of any one of claims 1 to 4, wherein the anti-B7-H3 antibody comprises a heavy chain and a light chain, wherein: (1) the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 55, 48, 49, 50, 51, 52, 53, 54, or 56, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 62, 57, 58, 59, 60, or 61; or the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 26, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 27; or the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 105, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 62; or (2) the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 78, 81, 76, 77, 79, or 80, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 83, 82, 84, 85, 86, or 87; or the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 28, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 29; or the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 108, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 83; or (3) the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 139, 129, 130, 131, 132, 133, 134, 135, 136, 137, or 138, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 141, 140, or 142; or the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 101, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 102; or the heavy chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 143, and the light chain comprises an amino acid sequence having at least 80% sequence identity to SEQ ID NO: 141; Preferably, (1) the heavy chain comprises an amino acid sequence of SEQ ID NO: 55, 48, 49, 50, 51, 52, 53, 54, or 56, and the light chain comprises an amino acid sequence of SEQ ID NO: 62, 57, 58, 59, 60, or 61; or the heavy chain comprises an amino acid sequence of SEQ ID NO: 26, and the light chain comprises an amino acid sequence of SEQ ID NO: 27; or the heavy chain comprises an amino acid sequence of SEQ ID NO: 105, and the light chain comprises an amino acid sequence of SEQ ID NO: 62; or (2) the heavy chain comprises an amino acid sequence of SEQ ID NO: 78, 81, 76, 77, 79, or 80, and the light chain comprises an amino acid sequence of SEQ ID NO: 83, 82, 84, 85, 86, or 87; or the heavy chain comprises an amino acid sequence of SEQ ID NO: 28, and the light chain comprises an amino acid sequence of SEQ ID NO: 29; or the heavy chain comprises an amino acid sequence of SEQ ID NO: 108, and the light chain comprises an amino acid sequence of SEQ ID NO: 83; or the heavy chain comprises an amino acid sequence of SEQ ID NO: 143, and the light chain comprises an amino acid sequence of SEQ ID NO:

141. (3) the heavy chain comprises the amino acid sequence of SEQ ID NO: 139, 129, 130, 131, 132, 133, 134, 135, 136, 137, or 138, and the light chain comprises the amino acid sequence of SEQ ID NO: 141, 140, or 142; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 101, and the light chain comprises the amino acid sequence of SEQ ID NO: 102; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 143, and the light chain comprises the amino acid sequence of SEQ ID NO: 141; more preferably, (1) the heavy chain comprises the amino acid sequence of SEQ ID NO: 55, and the light chain comprises the amino acid sequence of SEQ ID NO: 62; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 49, 50, 51, 52, 53, 54, 55, or 56, and the light chain comprises the amino acid sequence of SEQ ID NO: 57; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 49, 50, 51, 52, 53, or 54, and the light chain comprises the amino acid sequence of SEQ ID NO: 58; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 49, 50, 51, 52, 53, or 54, and the light chain comprises the amino acid sequence of SEQ ID NO: 59; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 55, or 56, and the light chain comprises the amino acid sequence of SEQ ID NO: 60; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 48, 55, or 56, and the light chain comprises the amino acid sequence of SEQ ID NO: 61; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 26, and the light chain comprises the amino acid sequence of SEQ ID NO: 27; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 105, and the light chain comprises the amino acid sequence of SEQ ID NO: 62; or (2) the heavy chain comprises the amino acid sequence of SEQ ID NO: 78, 76, 77, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 83; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 81, 76, 77, 78, 79, or 80, and the light chain comprises the amino acid sequence of SEQ ID NO: 82; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 76, 77, 78, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 84; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 76, 77, 78, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 85; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 76, 77, 78, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 85; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 76, 77, 78, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 86; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 76, 77, 78, 79, 80, or 81, and the light chain comprises the amino acid sequence of SEQ ID NO: 87; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 28, and the light chain comprises the amino acid sequence of SEQ ID NO: 29; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 108, and the light chain comprises the amino acid sequence of SEQ ID NO: 83; or (3) the heavy chain comprises the amino acid sequence of SEQ ID NO: 139, and the light chain comprises the amino acid sequence of SEQ ID NO: 141 or 142; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, or 139, and the light chain comprises the amino acid sequence of SEQ ID NO: 140; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 101, and the light chain comprises the amino acid sequence of SEQ ID NO: 102; or the heavy chain comprises the amino acid sequence of SEQ ID NO: 143, and the light chain comprises the amino acid sequence of SEQ ID NO: 141; most preferably, (1) the heavy chain comprises the amino acid sequence of SEQ ID NO: 55 or 105, and the light chain comprises the amino acid sequence of SEQ ID NO: 62; or (2) the heavy chain comprises the amino acid sequence of SEQ ID NO: 78 or 108, and the light chain comprises the amino acid sequence of SEQ ID NO: 83; or (3) the heavy chain comprises the amino acid sequence of SEQ ID NO: 139 or 143, and the light chain comprises the amino acid sequence of SEQ ID NO:

141.

6. The anti-B7-H3 antibody of any one of claims 1 to 3, wherein the anti-B7-H3 antibody is an antibody fragment; Preferably, the antibody fragment is selected from the group consisting of Fab, Fab', F(ab')2, Fv, scFv, and dsFv.

7. An immunoconjugate comprising a payload, and the anti-B7-H3 antibody of any one of claims 1 to 6 conjugated to the payload; Preferably, the payload is selected from the group consisting of a cytotoxic drug, an antitumor agent, a polypeptide, an oligonucleotide, an immunomodulatory agent, a biological response modifier, a lectin, a chromophore, a fluorophore, a chemiluminescent compound, an enzyme, a metal ion, and any combination thereof; More preferably, the payload is a cytotoxic drug.

8. A pharmaceutical composition comprising the anti-B7-H3 antibody of any one of claims 1 to 6, or the immunoconjugate of claim 7, and one or more pharmaceutically acceptable carriers, diluents, or excipients.

9. An isolated nucleic acid encoding the anti-B7-H3 antibody of any one of claims 1 to 6.

10. A host cell comprising the isolated nucleic acid of claim 9.

11. A method of treating or preventing a disease or disorder, the method comprising administering to a subject a therapeutically or prophylactically effective amount of the anti-B7-H3 antibody of any one of claims 1 to 6, or the immunoconjugate of claim 7, or the pharmaceutical composition of claim 8; Preferably, the disease or disorder is a tumor; More preferably, the disease or disorder is a solid tumor or a hematological tumor; Most preferably, the disease or disorder is neuroblastoma, lung cancer, breast cancer, ovarian cancer, prostate cancer, esophageal cancer, pancreatic cancer, endometrial cancer, gastric cancer, melanoma, liver cancer, colorectal cancer, central nervous system cancer, glioma, glioblastoma, glioblastoma multiforme, head and neck cancer, squamous cell carcinoma, sarcoma, brain cancer, nasopharyngeal cancer, renal cancer, endometrial cancer, or bladder cancer.

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