Anti-CLDN18.2 antibody drug conjugate as well as pharmaceutical composition and application thereof

Abstract

Belongs to the technical field of biology, and provides an anti-CLDN18.2 antibody drug conjugate and a pharmaceutical composition and application thereof, and the antibody drug conjugate comprises an antibody or an antigen binding fragment thereof, a linker and a cytotoxic drug which are connected. The antibody drug conjugate provided by the invention realizes excellent anti-tumor activity or / and relatively good safety. The provided antibody drug conjugate can be used for tumor treatment.

Description

Anti-CLDN18.2 antibody-drug conjugate and its pharmaceutical composition and use

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefits of Chinese patent application No. CN 202211521035.0, filed on November 30, 2022, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present disclosure belongs to the field of biotechnology and relates to antibody-drug conjugates, which include linked antibodies or antigen-binding fragments thereof, linkers, and payloads (e.g., cytotoxic drugs). The present disclosure also relates to the use of the antibody-drug conjugates in the preparation of drugs for treating tumors. Background Art

[0004] Claudin 18 (CLDN18 or Claudin 18) belongs to the tight junction protein family and participates in the formation of tight junctions between cells, controlling the flow of molecules between cells and playing an important role in maintaining cell polarity, permeability, and intercellular signaling. CLDN18 is a four-transmembrane protein with both its N- and C-termini located intracellularly and forming two extracellular loop regions. Due to alternative RNA splicing, two distinct isoforms exist in tissues: claudin 18.1 (CLDN18.1, for example, the Uniprot accession number for human CLDN18.1 is P56856-1) and claudin 18.2 (CLDN18.2, for example, the Uniprot accession number for human CLDN18.2 is P56856-2).

[0005] The protein sequences of CLDN18.1 (Claudin 18.1) and CLDN18.2 (Claudin 18.2) are highly similar, but their expression distributions are different. CLDN18.1 is selectively expressed in normal lung tissue, while CLDN18.2 is expressed very limitedly in normal tissues and is specifically expressed only in differentiated epithelial cells of the gastric mucosa. However, studies have found that CLDN18.2 is highly expressed in 70% of primary gastric cancers and their metastases. In addition, CLDN18.2 has been found to be frequently ectopically activated in a variety of malignant tumors, including pancreatic cancer, esophageal cancer, lung cancer, breast cancer, ovarian cancer, and otolaryngology tumors (Niimi et al., (2001) Mol Cell Biol 21(21):7380-7390; Sahin, U. et al., (2008) Clin Cancer Res. 14,7624-34; Tanaka et al., (2011) J Histochem Cytochem 59(10):942-952; Micke et al., (2014) Int J Cancer 135(9):2206-2214; Shimobaba et al., (2016) Biochim Biophys Acta 1863(6Pt A): 1170-1178; Sing h et al., (2017) J Hematol Oncol 10(1): 105; Tokumitsu et al., (2017) Cytopathology 28(2): 116-121).

[0006] Antibody-drug conjugates (ADCs) are a class of drugs that combine the high specificity of therapeutic antibodies with the high cytotoxic activity of cytotoxic drugs. The therapeutic antibody and cytotoxic drug are linked via a linker. While there have been reports of developing ADCs for anti-tumor efficacy targeting the CLDN18.2 target, current research is limited, and more options are needed.

[0007] Summary of the Invention

[0008] Antibody-drug conjugates (ADCs)

[0009] The present disclosure provides an antibody-drug conjugate, wherein an antibody or an antigen-binding fragment thereof is conjugated to a cytotoxic drug, and the antibody or the antigen-binding fragment thereof specifically binds to CLDN18.2.

[0010] In one aspect, the present disclosure provides a compound of the formula Ab-(LU) nThe antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein Ab is an antibody or an antigen-binding fragment thereof, L is a linker, and U is a cytotoxic drug. In some embodiments, n is an integer selected from 1-10.

[0011] In some embodiments, the antibody or antigen-binding fragment thereof Ab is connected to the linker L through a specific functional group, and the antibody or antigen-binding fragment thereof can specifically bind to the antigen. In some embodiments, Ab is connected to the linker L through a covalent bond.

[0012] In some embodiments, the antibody or antigen-binding fragment thereof binds to human CLDN18.2.

[0013] In some embodiments, the antibody or its antigen-binding fragment is a murine antibody, a chimeric antibody, a humanized antibody or a human antibody. In some embodiments, the antibody or its antigen-binding fragment is a monoclonal antibody, a monospecific antibody, a multispecific antibody, a Fab fragment, a F(ab')2 fragment, a Fd fragment, a Fv fragment, a dAb, a single-chain Fv (scFv) molecule or a nanobody.

[0014] In some embodiments, the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises heavy chain CDR (HCDR) 1, HCDR2, HCDR3, light chain CDR (LCDR) 1, LCDR2, and LCDR3, wherein:

[0015] (1) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 11, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 11, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 11, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 16, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 16, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 16;

[0016] (2) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 12, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 12, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 12, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 17, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 17, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 17;

[0017] (3) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 13, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 13, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 13, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 17, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 17, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 17;

[0018] (4) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 14, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 14, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 14, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 17, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 17, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 17;

[0019] (5) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 15, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 15, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 15, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 17, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 17, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 17;

[0020] (6) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 12, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 12, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 12, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 18, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 18, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 18;

[0021] (7) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 13, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 13, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 13, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 18, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 18, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 18;

[0022] (8) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 14, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 14, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 14, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 18, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 18, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 18;

[0023] (9) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 15, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 15, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 15, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 18, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 18, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 18;

[0024] (10) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 29, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 29, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 29, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 34, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 34, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 34;

[0025] (11) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 30, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 30, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 30, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 35, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 35, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 35;

[0026] (12) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 31, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 31, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 31, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 35, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 35, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 35;

[0027] (13) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 32, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 32, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 32, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 35, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 35, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 35;

[0028] (14) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 33, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 33, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 33, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 35, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 35, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 35;

[0029] (15) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 30, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 30, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 30, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 36, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 36, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 36;

[0030] (16) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 31, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 31, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 31, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 36, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 36, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 36;

[0031] (17) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 32, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 32, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 32, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 36, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 36, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 36;

[0032] (18) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 33, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 33, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 33, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 36, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 36, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 36;

[0033] (19) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 43, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 43, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 44, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 44, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 44;

[0034] (20) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 51, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 51, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 52, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 52, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 52; or

[0035] (21) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 59, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 59, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 59, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 60, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 60, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 60.

[0036] In some embodiments, the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3, wherein:

[0037] (1) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 3, 4, 7, 8, 9 and 10, respectively;

[0038] (2) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence set forth in SEQ ID NOs: 3, 5, 7, 8, 9 and 10, respectively;

[0039] (3) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence set forth in SEQ ID NOs: 3, 6, 7, 8, 9 and 10, respectively;

[0040] (4) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 19, 20, 24, 25, 26 and 27, respectively;

[0041] (5) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 19, 21, 24, 25, 26 and 27, respectively;

[0042] (6) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 19, 22, 24, 25, 26 and 27, respectively;

[0043] (7) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 19, 23, 24, 25, 26 and 27, respectively;

[0044] (8) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 19, 20, 24, 25, 26 and 28, respectively;

[0045] (9) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 19, 21, 24, 25, 26 and 28, respectively;

[0046] (10) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 19, 22, 24, 25, 26 and 28, respectively;

[0047] (11) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 19, 23, 24, 25, 26 and 28, respectively;

[0048] (12) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 37, 38, 39, 40, 41 and 42, respectively;

[0049] (13) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence set forth in SEQ ID NOs: 45, 46, 47, 48, 49 and 50, respectively; or

[0050] (14) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence set forth in SEQ ID NOs: 53, 54, 55, 56, 57 and 58, respectively.

[0051] In some embodiments, the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3, wherein:

[0052] (1) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences of SEQ ID NOs: 3, 69, 7, 8, 9, and 10, respectively;

[0053] (2) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 70, 24, 25, 26, and 71, respectively;

[0054] (3) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 37, 38, 39, 40, 41, and 42, respectively;

[0055] (4) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences of SEQ ID NOs: 45, 46, 47, 48, 49, and 50, respectively; or

[0056] (5) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise the amino acid sequences shown in SEQ ID NOs: 53, 54, 55, 56, 57 and 58, respectively.

[0057] In some embodiments, the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3, wherein:

[0058] (1) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 3, 4, 7, 8, 9, and 10, respectively;

[0059] (2) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 3, 5, 7, 8, 9, and 10, respectively;

[0060] (3) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 3, 6, 7, 8, 9, and 10, respectively;

[0061] (4) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 20, 24, 25, 26, and 27, respectively;

[0062] (5) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 21, 24, 25, 26, and 27, respectively;

[0063] (6) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 22, 24, 25, 26, and 27, respectively;

[0064] (7) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 23, 24, 25, 26, and 27, respectively;

[0065] (8) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 20, 24, 25, 26, and 28, respectively;

[0066] (9) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 21, 24, 25, 26, and 28, respectively;

[0067] (10) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 22, 24, 25, 26, and 28, respectively;

[0068] (11) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences of SEQ ID NOs: 19, 23, 24, 25, 26, and 28, respectively;

[0069] (12) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 37, 38, 39, 40, 41, and 42, respectively;

[0070] (13) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise the amino acid sequences of SEQ ID NOs: 45, 46, 47, 48, 49 and 50, respectively; or

[0071] (14) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise the amino acid sequences shown in SEQ ID NOs: 53, 54, 55, 56, 57 and 58, respectively.

[0072] In some embodiments, the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3, wherein:

[0073] (1) The amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are shown in SEQ ID NOs: 3, 4, 7, 8, 9, and 10, respectively;

[0074] (2) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are shown in SEQ ID NOs: 3, 5, 7, 8, 9, and 10, respectively;

[0075] (3) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are shown in SEQ ID NOs: 3, 6, 7, 8, 9, and 10, respectively;

[0076] (4) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are shown in SEQ ID NOs: 19, 20, 24, 25, 26, and 27, respectively;

[0077] (5) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are shown in SEQ ID NOs: 19, 21, 24, 25, 26, and 27, respectively;

[0078] (6) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are shown in SEQ ID NOs: 19, 22, 24, 25, 26, and 27, respectively;

[0079] (7) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are shown in SEQ ID NOs: 19, 23, 24, 25, 26, and 27, respectively;

[0080] (8) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are shown in SEQ ID NOs: 19, 20, 24, 25, 26, and 28, respectively;

[0081] (9) The amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are shown in SEQ ID NOs: 19, 21, 24, 25, 26, and 28, respectively;

[0082] (10) The amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are shown in SEQ ID NOs: 19, 22, 24, 25, 26, and 28, respectively;

[0083] (11) The amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are shown in SEQ ID NOs: 19, 23, 24, 25, 26, and 28, respectively;

[0084] (12) The amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are shown in SEQ ID NOs: 37, 38, 39, 40, 41, and 42, respectively;

[0085] (13) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are shown in SEQ ID NOs: 45, 46, 47, 48, 49 and 50, respectively; or

[0086] (14) The amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are shown in SEQ ID NOs: 53, 54, 55, 56, 57, and 58, respectively.

[0087] In some embodiments, the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises a heavy chain variable region and a light chain variable region, wherein:

[0088] (1) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 11 and 16, respectively;

[0089] (2) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 12 and 17, respectively;

[0090] (3) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 13 and 17, respectively;

[0091] (4) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 14 and 17, respectively;

[0092] (5) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence set forth in SEQ ID NOs: 15 and 17, respectively;

[0093] (6) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence set forth in SEQ ID NOs: 12 and 18, respectively;

[0094] (7) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence set forth in SEQ ID NOs: 13 and 18, respectively;

[0095] (8) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 14 and 18, respectively;

[0096] (9) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 15 and 18, respectively;

[0097] (10) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence set forth in SEQ ID NOs: 29 and 34, respectively;

[0098] (11) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 30 and 35, respectively;

[0099] (12) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 31 and 35, respectively;

[0100] (13) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence set forth in SEQ ID NOs: 32 and 35, respectively;

[0101] (14) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 33 and 35, respectively;

[0102] (15) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 30 and 36, respectively;

[0103] (16) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 31 and 36, respectively;

[0104] (17) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 32 and 36, respectively;

[0105] (18) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 33 and 36, respectively;

[0106] (19) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence set forth in SEQ ID NOs: 43 and 44, respectively;

[0107] (20) the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequences set forth in SEQ ID NOs: 51 and 52, respectively; or

[0108] (21) The heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence set forth in SEQ ID NOs: 59 and 60, respectively.

[0109] In some embodiments, the amino acids that differ in an amino acid sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identity to the amino acid sequence set forth in any one of SEQ ID NOs: 11-18, 29-36, 43-44, 51-52, 59-60 are primarily (or entirely) located in the FR regions (framework regions).

[0110] In some embodiments, the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises a heavy chain variable region and a light chain variable region, wherein:

[0111] (1) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 11 and 16, respectively;

[0112] (2) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 12 and 17, respectively;

[0113] (3) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 13 and 17, respectively;

[0114] (4) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 14 and 17, respectively;

[0115] (5) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 15 and 17, respectively;

[0116] (6) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 12 and 18, respectively;

[0117] (7) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 13 and 18, respectively;

[0118] (8) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 14 and 18, respectively;

[0119] (9) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 15 and 18, respectively;

[0120] (10) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 29 and 34, respectively;

[0121] (11) The heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 30 and 35, respectively;

[0122] (12) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 31 and 35, respectively;

[0123] (13) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 32 and 35, respectively;

[0124] (14) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 33 and 35, respectively;

[0125] (15) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 30 and 36, respectively;

[0126] (16) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 31 and 36, respectively;

[0127] (17) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 32 and 36, respectively;

[0128] (18) The heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 33 and 36, respectively;

[0129] (19) the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 43 and 44, respectively;

[0130] (20) The heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 51 and 52, respectively; or

[0131] (21) The heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 59 and 60, respectively.

[0132] Herein, various variants of the above-mentioned anti-CLDN18.2 antibodies or antigen-binding fragments thereof retain the ability to specifically bind to the antigen CLDN18.2.

[0133] Table S1 provides CDR sequences and variable region sequences of some exemplary anti-CLDN18.2 antibodies or antigen-binding fragments thereof, wherein some anti-CLDN18.2 antibodies or antigen-binding fragments thereof have the same CDRs, and some anti-CLDN18.2 antibodies or antigen-binding fragments thereof have the same VH or VL.

[0134] Table S1 Amino acid sequence IDs of variable regions and CDRs (SEQ ID NO.)

[0135] For the amino acid sequence of the antibody variable region, those skilled in the art can determine which residues constitute a specific CDR by conventional methods. As is well known to those skilled in the art, the CDRs of an antibody can be defined by a variety of methods, such as using numbering systems / methods such as Kabat, Chothia, IMGT, AbM, or Contact; or using a combination of two or more of the numbering systems / methods such as Kabat, Chothia, IMGT, AbM, and Contact; or using a combined numbering system that includes Kabat and Chothia, where the combined numbering system combines the ranges defined by Kabat and Chothia to create a larger range (e.g., if HCDR1 defined by Kabat is H31-H35 and HCDR1 defined by Chothia is H26-H32, then HCDR1 defined by the combined system is H26-H35). The precise numbering and position of the CDRs vary in different numbering systems. It will be understood by those skilled in the art that, unless otherwise specified, the terms "CDR" and "complementarity determining region" of a given antibody or region thereof (e.g., variable region) should be understood to encompass complementarity determining regions defined by any known scheme. Although the CDRs claimed in this disclosure are based on the sequences shown in Table S1 (one definition), amino acid sequences corresponding to other CDR definition rules should also fall within the scope of protection of this disclosure.

[0136] In one embodiment, the antibody or antigen-binding fragment thereof of the present disclosure is selected from 28G3 antibody or antigen-binding fragment thereof, 40F6 antibody or antigen-binding fragment thereof, 34G6 antibody or antigen-binding fragment thereof, 10D8 antibody or antigen-binding fragment thereof, or 22F12 antibody or antigen-binding fragment thereof, wherein,

[0137] The 28G3 antibody or antigen-binding fragment thereof comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3, which comprise the amino acid sequences shown in SEQ ID NOs: 3, 69, 7, 8, 9 and 10, respectively; preferably, the 28G3 antibody or antigen-binding fragment thereof comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3, wherein (1) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are shown in SEQ ID NOs: 3, 4, 7, 8, 9 and 10, respectively; (2) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are shown in SEQ ID NOs: 3, 5, 7, 8, 9 and 10, respectively; or (3) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are shown in SEQ ID NOs: NOs: 3, 6, 7, 8, 9 and 10;

[0138] The 40F6 antibody or its antigen-binding fragment comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3, which comprise the amino acid sequences shown in SEQ ID NOs: 19, 70, 24, 25, 26 and 71, respectively; preferably, the 40F6 antibody or its antigen-binding fragment comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3, wherein (1) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are shown in SEQ ID NOs: 19, 20, 24, 25, 26 and 27, respectively; (2) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are shown in SEQ ID NOs: NOs: 19, 21, 24, 25, 26 and 27; (3) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are shown in SEQ ID NOs: 19, 22, 24, 25, 26 and 27, respectively; (4) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are shown in SEQ ID NOs: 19, 23, 24, 25, 26 and 27, respectively; (5) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are shown in SEQ ID NOs: 19, 20, 24, 25, 26 and 28, respectively; (6) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are shown in SEQ ID NOs: 19, 22, 24, 25, 26 and 27, respectively. NOs: 19, 21, 24, 25, 26 and 28; (7) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are shown in SEQ ID NOs: 19, 22, 24, 25, 26 and 28, respectively; or (8) the amino acid sequences of HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 are shown in SEQ ID NOs: 19, 23, 24, 25, 26 and 28, respectively;

[0139] The 34G6 antibody or antigen-binding fragment thereof comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences shown as 37, 38, 39, 40, 41, and 42, respectively;

[0140] The 10D8 antibody or antigen-binding fragment thereof comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprising the amino acid sequences shown at 45, 46, 47, 48, 49, and 50, respectively; or

[0141] The 22F12 antibody or antigen-binding fragment thereof comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3, which comprise the amino acid sequences shown as 53, 54, 55, 56, 57, and 58, respectively;

[0142] In some preferred embodiments, the 28G3 antibody or antigen-binding fragment thereof comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region and the light chain variable region comprise the amino acid sequences of SEQ ID NOs: 11 and 16, SEQ ID NOs: 12 and 17, SEQ ID NOs: 13 and 17, SEQ ID NOs: 14 and 17, SEQ ID NOs: 15 and 17, SEQ ID NOs: 12 and 18, SEQ ID NOs: 13 and 18, SEQ ID NOs: 14 and 18, or SEQ ID NOs: 15 and 18, respectively;

[0143] The 40F6 antibody or antigen-binding fragment thereof comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region and the light chain variable region comprise the amino acid sequences of SEQ ID NOs: 29 and 34, SEQ ID NOs: 30 and 35, SEQ ID NOs: 31 and 35, SEQ ID NOs: 32 and 35, SEQ ID NOs: 33 and 35, SEQ ID NOs: 30 and 36, SEQ ID NOs: 31 and 36, SEQ ID NOs: 32 and 36, or SEQ ID NOs: 33 and 36, respectively;

[0144] The 34G6 antibody or antigen-binding fragment thereof comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 43 and 44, respectively;

[0145] The 10D8 antibody or antigen-binding fragment thereof comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 51 and 52, respectively; or

[0146] The 22F12 antibody or antigen-binding fragment thereof comprises a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region and the light chain variable region comprise the amino acid sequences shown in SEQ ID NOs: 59 and 60, respectively.

[0147] The VH and / or VL sequences (or CDR sequences) of other antibodies that bind to CLDN18.2 can be "mixed and paired" with the VH and / or VL sequences (or CDR sequences) of the anti-CLDN18.2 antibodies or antigen-binding fragments thereof disclosed herein. Preferably, when the VH and VL chains (or their CDRs) are mixed and paired, the VH sequence in a particular VH / VL pair can be replaced with a structurally similar VH sequence. Similarly, the VL sequence in a particular VH / VL pair is preferably replaced with a structurally similar VL sequence.

[0148] Thus, in one embodiment, the antibodies or antigen-binding fragments thereof of the present disclosure comprise:

[0149] (a) a heavy chain variable region comprising the amino acid sequence listed in Table S1; and

[0150] (b) a light chain variable region comprising the amino acid sequence listed in Table S1, or the VL of another anti-CLDN18.2 antibody, wherein the antibody or antigen-binding fragment thereof specifically binds to CLDN18.2.

[0151] In another embodiment, the antibody or antigen-binding fragment thereof of the present disclosure comprises:

[0152] (a) HCDR1, HCDR2 and HCDR3 listed in Table S1; and

[0153] (b) LCDR1, LCDR2 and LCDR3 listed in Table S1, or the light chain variable region CDRs of another anti-CLDN18.2 antibody, wherein the antibody or antigen-binding fragment thereof specifically binds to CLDN18.2.

[0154] In another embodiment, the antibodies or antigen-binding fragments thereof of the present disclosure include the HCDR2 listed in Table S1 and the CDR(s) of other anti-CLDN18.2 antibodies, such as HCDR1 and / or HCDR3 of other anti-CLDN18.2 antibodies, and / or LCDR1, LCDR2 and / or LCDR3 of other anti-CLDN18.2 antibodies.

[0155] Furthermore, it is well known in the art that the CDR3 domain, independent of the CDR1 and / or CDR2 domains, can independently determine the binding specificity of an antibody to the same antigen, and it can be predicted that multiple antibodies with the same binding specificity can be generated based on the CDR3 sequence.

[0156] In another embodiment, the antibody or antigen-binding fragment thereof of the present disclosure comprises a HCDR2 listed in Table S1, and a HCDR3 listed in Table S1 and / or a LCDR3 listed in Table S1, as well as CDR(s) of other anti-CLDN18.2 antibodies, wherein the antibody or antigen-binding fragment thereof specifically binds to CLDN18.2. In another embodiment, the antibody or antigen-binding fragment thereof of the present disclosure further comprises a LCDR2 listed in Table S1, as well as CDR(s) of other anti-CLDN18.2 antibodies, wherein the antibody or antigen-binding fragment thereof specifically binds to CLDN18.2. In another embodiment, the antibody or antigen-binding fragment thereof of the present disclosure further comprises a HCDR1 listed in Table S1 or a LCDR1 listed in Table S1, as well as CDR(s) of other anti-CLDN18.2 antibodies, wherein the antibody or antigen-binding fragment thereof specifically binds to CLDN18.2. These antibodies preferably (a) compete for binding to CLDN18.2; (b) retain the same functional characteristics; (c) bind to the same epitope; and / or (d) have similar binding affinity as the anti-CLDN18.2 antibodies of the present disclosure.

[0157] In some embodiments, the anti-CLDN18.2 antibody or antigen-binding fragment thereof further comprises a heavy chain constant region and a light chain constant region; wherein the heavy chain constant region comprises a human IgG1, IgG2, or IgG4 constant region or a variant thereof, preferably a human IgG1 constant region or a variant thereof, and the light chain constant region comprises a human kappa constant region, a human lambda constant region or a variant thereof, preferably a human kappa constant region or a variant thereof. Exemplary variants include IgG1, IgG2, or IgG4 heavy chain constant region variants in which the heavy chain constant region is subjected to site-directed modification and amino acid substitutions, such as the AAA mutation, DLE mutation (Shields et al., 2002; Lazar et al., 2006), YTE mutation, and LS mutation (Ghetie et al., 1997; Zalevsky et al., 2010) known in the art. The C-terminal lysine in the heavy chain constant region may be present or absent.

[0158] In some embodiments, the heavy chain constant region comprises the amino acid sequence shown in SEQ ID NO:1, or an amino acid sequence having 1, 2, 3, 4 or 5 amino acid substitutions, deletions and additions compared to the amino acid sequence shown in SEQ ID NO:1, and the light chain constant region comprises the amino acid sequence shown in SEQ ID NO:2, or an amino acid sequence having 1, 2, 3, 4 or 5 amino acid substitutions, deletions and additions compared to the amino acid sequence shown in SEQ ID NO:2.

[0159] In this article, the amino acid substitution can be a conservative amino acid substitution, that is, a substitution with another amino acid of the same type (having similar chemical properties or functions). As an example, amino acids can be divided into the following categories based on their side chain properties: (1) non-polar amino acids: Ala (A), Val (V), Leu (L), Ile (I), Pro (P), Phe (F), Trp (W), Met (M); (2) uncharged polar amino acids: Gly (G), Ser (S), Thr (T), Cys (C), Tyr (Y), Asn (N), Gln (Q); (3) acidic amino acids: Asp (D), Glu (E); (4) basic amino acids: Lys (K), Arg (R), His (H). Alternatively, amino acids can be divided into the following categories based on common side chain properties: (1) hydrophobic amino acids: Met, Ala, Val, Leu, Ile; (2) neutral hydrophilic amino acids: Cys, Ser, Thr, Asn, Gln; (3) acidic amino acids: Asp, Glu; (4) basic amino acids: His, Lys, Arg; (5) amino acids that affect chain orientation: Gly, Pro; (6) aromatic amino acids: Trp, Tyr, Phe.

[0160] In some embodiments, the anti-CLDN18.2 antibody is a full-length antibody, such as a full-length antibody of the IgG1 isotype. In another embodiment, the anti-CLDN18.2 antibody or antigen-binding fragment thereof is a Fab fragment, a F(ab')2 fragment, a Fd fragment, an Fv fragment, a dAb, a single-chain Fv (scFv) molecule, or a nanobody.

[0161] In some embodiments, the anti-CLDN18.2 antibody comprises a heavy chain comprising an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence of SEQ ID NO: 61, and a light chain comprising an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence of SEQ ID NO: 62.

[0162] In some embodiments, the anti-CLDN18.2 antibody comprises a heavy chain comprising an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence of SEQ ID NO: 63, and a light chain comprising an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence of SEQ ID NO: 64.

[0163] In some embodiments, the anti-CLDN18.2 antibody comprises a heavy chain comprising the amino acid sequence shown in SEQ ID NO:61 and a light chain comprising the amino acid sequence shown in SEQ ID NO:62.

[0164] In some embodiments, the anti-CLDN18.2 antibody comprises a heavy chain comprising the amino acid sequence shown in SEQ ID NO:63 and a light chain comprising the amino acid sequence shown in SEQ ID NO:64.

[0165] It will be appreciated that some anti-CLDN18.2 antibodies are also provided in which the C-terminal lysine of the heavy chain is deleted.

[0166] In some specific embodiments, the present disclosure provides the general formula Ab-(LU) n In the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, L is a linker, U is a cytotoxic drug, n is an integer selected from 1-10, and the Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, which comprises the HCDR1 shown in SEQ ID NO: 3, the HCDR2 shown in SEQ ID NO: 5, the HCDR3 shown in SEQ ID NO: 7, the LCDR1 shown in SEQ ID NO: 8, the LCDR2 shown in SEQ ID NO: 9, and the LCDR3 shown in SEQ ID NO: 10.

[0167] In some specific embodiments, the present disclosure provides the general formula Ab-(LU) nIn the antibody-drug conjugate or pharmaceutically acceptable salt or solvate thereof, L is a linker, U is a cytotoxic drug, and n is an integer selected from 1-10. The Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, which comprises a heavy chain variable region and a light chain variable region, the heavy chain variable region comprising an amino acid sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identity to the amino acid sequence of SEQ ID NO: 12, and the light ... An amino acid sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identity to the amino acid sequence of NO: 17. Further, in these specific embodiments, the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises HCDR1 of SEQ ID NO: 3, HCDR2 of SEQ ID NO: 5, HCDR3 of SEQ ID NO: 7, LCDR1 of SEQ ID NO: 8, LCDR2 of SEQ ID NO: 9, and LCDR3 of SEQ ID NO: 10.

[0168] In other specific embodiments, the present disclosure provides a general formula of Ab-(LU) nIn the antibody-drug conjugate or pharmaceutically acceptable salt or solvate thereof, L is a linker, U is a cytotoxic drug, and n is an integer selected from 1-10. The Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, which comprises a heavy chain variable region and a light chain variable region, the heavy chain variable region comprising an amino acid sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identity to the amino acid sequence of SEQ ID NO: 14, and the light ... An amino acid sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identity to the amino acid sequence of NO: 17. Further, in these specific embodiments, the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises HCDR1 of SEQ ID NO: 3, HCDR2 of SEQ ID NO: 5, HCDR3 of SEQ ID NO: 7, LCDR1 of SEQ ID NO: 8, LCDR2 of SEQ ID NO: 9, and LCDR3 of SEQ ID NO: 10.

[0169] In some specific embodiments, the present disclosure provides the general formula Ab-(LU) n In the antibody-drug conjugate or its pharmaceutically acceptable salt or solvate, L is a linker, U is a cytotoxic drug, n is an integer selected from 1-10, and the Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, which comprises a heavy chain variable region and a light chain variable region, the heavy chain variable region comprises the amino acid sequence shown in SEQ ID NO: 12, and the light chain variable region comprises the amino acid sequence shown in SEQ ID NO: 17. In other specific embodiments, the general formula provided by the present disclosure is Ab-(LU) n In the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, L is a linker, U is a cytotoxic drug, n is an integer selected from 1-10, and the Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, which comprises a heavy chain variable region and a light chain variable region, the heavy chain variable region comprises the amino acid sequence shown in SEQ ID NO: 14, and the light chain variable region comprises the amino acid sequence shown in SEQ ID NO: 17.

[0170] In some specific embodiments, the present disclosure provides the general formula Ab-(LU) nIn the antibody-drug conjugate or its pharmaceutically acceptable salt or solvate, L is a linker, U is a cytotoxic drug, n is an integer selected from 1-10, and the Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, which comprises a heavy chain variable region and a light chain variable region, the amino acid sequence of the heavy chain variable region is shown in SEQ ID NO: 12, and the amino acid sequence of the light chain variable region is shown in SEQ ID NO: 17. In other specific embodiments, the general formula provided by the present disclosure is Ab-(LU) n In the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, L is a linker, U is a cytotoxic drug, n is an integer selected from 1-10, and the Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, which comprises a heavy chain variable region and a light chain variable region, the amino acid sequence of the heavy chain variable region is shown in SEQ ID NO: 14, and the amino acid sequence of the light chain variable region is shown in SEQ ID NO: 17.

[0171] In some specific embodiments, the present disclosure provides the general formula Ab-(LU) n In the antibody-drug conjugate or its pharmaceutically acceptable salt or solvate, L is a linker, U is a cytotoxic drug, n is an integer selected from 1-10, and the Ab is an anti-CLDN18.2 antibody comprising a heavy chain and a light chain, wherein the heavy chain comprises the amino acid sequence shown in SEQ ID NO: 61 and the light chain comprises the amino acid sequence shown in SEQ ID NO: 62. In other specific embodiments, the general formula provided by the present disclosure is Ab-(LU) n In the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, L is a linker, U is a cytotoxic drug, n is an integer selected from 1-10, and the Ab is an anti-CLDN18.2 antibody comprising a heavy chain and a light chain, the heavy chain comprising the amino acid sequence shown in SEQ ID NO: 63, and the light chain comprising the amino acid sequence shown in SEQ ID NO: 64.

[0172] In some specific embodiments, the present disclosure provides the general formula Ab-(LU) n In the antibody-drug conjugate or its pharmaceutically acceptable salt or solvate, L is a linker, U is a cytotoxic drug, n is an integer selected from 1-10, and the Ab is an anti-CLDN18.2 antibody comprising a heavy chain and a light chain, the amino acid sequence of the heavy chain is shown in SEQ ID NO: 61, and the amino acid sequence of the light chain is shown in SEQ ID NO: 62. In other specific embodiments, the general formula provided by the present disclosure is Ab-(LU) nIn the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, L is a linker, U is a cytotoxic drug, n is an integer selected from 1-10, and the Ab is an anti-CLDN18.2 antibody comprising a heavy chain and a light chain, the amino acid sequence of the heavy chain is as shown in SEQ ID NO: 63, and the amino acid sequence of the light chain is as shown in SEQ ID NO: 64. In other specific embodiments, the C-terminal Lys of the heavy chain (e.g., SEQ ID NO: 63 or SEQ ID NO: 61) is absent.

[0173] In some embodiments, the anti-CLDN18.2 antibody comprises two heavy chains (H) and two light chains (L), or consists of two heavy chains and two light chains, the heavy chains and the light chains are interconnected by disulfide bonds, wherein each heavy chain comprises the above-mentioned heavy chain variable region (VH) and a heavy chain constant region, wherein the heavy chain variable region (VH) comprises a framework region (FR) and the above-mentioned heavy chain complementarity determining region (HCDR), and each light chain comprises the above-mentioned light chain variable region (VL) and a light chain constant region, wherein the light chain variable region (VL) comprises a FR and the above-mentioned light chain complementarity determining region (LCDR), wherein the C-terminus of the heavy chain variable region is linked to the N-terminus of the heavy chain constant region, and the C-terminus of the light chain variable region is linked to the N-terminus of the light chain constant region.

[0174] In some embodiments, the anti-CLDN18.2 antibody or antigen-binding fragment thereof can be modified, for example, by altering, adding, or removing one or more amino acids. In this context, the modified antibody or antigen-binding fragment thereof still retains the activity of specifically binding to its corresponding antigen.

[0175] The general formula provided by the present disclosure is Ab-(LU) n In the antibody-drug conjugate or its pharmaceutically acceptable salt or solvate, Ab is an antibody or an antigen-binding fragment thereof, which binds to CLDN18.2, thereby inducing antibody-dependent cell-mediated cytotoxicity (ADCC) and / or complement-dependent cytotoxicity (CDC) against cells expressing CLDN18.2. In some embodiments, the general formula is Ab-(LU) n In an antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, the antibody or antigen-binding fragment thereof binds to human CLDN18.2, thereby inducing ADCC and CDC against cells expressing human CLDN18.2. In some embodiments, the general formula is Ab-(LU) n In an antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, the antibody or antigen-binding fragment thereof does not bind to CLDN18.1. In some embodiments, the general formula is Ab-(LU) nIn an antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, the antibody or antigen-binding fragment thereof does not bind to human CLDN18.1. In some embodiments, the general formula is Ab-(LU) n The antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof does not induce ADCC and / or CDC against cells expressing CLDN18.1. In some embodiments, the general formula is Ab-(LU) n The antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof does not induce ADCC and / or CDC against cells expressing human CLDN18.1.

[0176] The general formula provided by the present disclosure is Ab-(LU) n In the antibody-drug conjugate or its pharmaceutically acceptable salt or solvate thereof, the cytotoxic drug U is coupled to the antibody or its antigen-binding fragment Ab via a linker L. In some specific embodiments, in the antibody-drug conjugate or its pharmaceutically acceptable salt or solvate provided by the present disclosure, each cytotoxic drug U is coupled to the antibody or its antigen-binding fragment Ab via a linker L. The linker L disclosed herein can be connected to the antibody or its antigen-binding fragment by any method known in the art. In some preferred embodiments, the linker L is connected to the antibody or its antigen-binding fragment Ab via a sulfhydryl group and / or an amino group. In some more preferred embodiments, the linker L is connected to the antibody or its antigen-binding fragment Ab via a sulfhydryl group.

[0177] In some embodiments, the linker L is a cleavable linker or a non-cleavable linker. In some embodiments, the linker is a cleavable linker, for example, it can be a low pH degradation type (including hydrazone bonds, carbonate bonds, etc.), a proteolytic type (including peptidyl bonds), or a high glutathione concentration degradation type (including disulfide bonds). The cleavable linker can be broken in the target cell, thereby releasing the cytotoxic drug. In other embodiments, the linker L is a non-cleavable linker, for example, it can be a maleimidohexanoyl group, etc.

[0178] In one aspect, the present disclosure provides a general formula of Ab-(LU) nIn the antibody-drug conjugate or its pharmaceutically acceptable salt or solvate, the antibody or its antigen-binding fragment Ab is coupled to one or more cytotoxic drugs U, and the cytotoxic drugs can be, for example, alkaloids, antimetabolites, antitumor antibiotics, alkylating agents, and platinums. In some embodiments, the cytotoxic drug U is a tubulin inhibitor cytotoxic drug or a cytotoxic drug that acts on DNA. In some embodiments, the tubulin inhibitor cytotoxic drugs include but are not limited to maytansines (e.g., DM1, DM4), auristatins (e.g., MMAE or MMAF), and dolastatin. In some embodiments, the cytotoxic drugs that act on DNA include but are not limited to calicheamicins, doxorubicin, duocarmycins, anthramycin derivatives PBD (pyrrolobenzodiazepine), and topoisomerase I inhibitors.

[0179] In some specific embodiments, the present disclosure provides the general formula Ab-(LU) n In the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, the cytotoxic drug U is a topoisomerase I inhibitor.

[0180] In some specific embodiments, the present disclosure provides the general formula Ab-(LU) n In the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, the cytotoxic drug U is a camptothecin topoisomerase I inhibitor.

[0181] In some specific embodiments, the present disclosure provides the general formula Ab-(LU) n In the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, the cytotoxic drug U is SN-38, an SN-38 derivative, exatecan, or an exatecan derivative. In some specific embodiments, the cytotoxic drug U is deuterated. In some specific embodiments, the cytotoxic drug U is an exatecan derivative and is deuterated.

[0182] In some embodiments, the cytotoxic drug U is connected to the linker L via a functional group, and the cytotoxic drug molecules are released in tumor cells, thereby exerting an anti-tumor effect.

[0183] In one aspect, the present disclosure provides a general formula of Ab-(LU) nIn the antibody-drug conjugate or pharmaceutically acceptable salt or solvate thereof, Ab is an antibody or antigen-binding fragment thereof, L is a linker, U is a camptothecin-type topoisomerase I inhibitor, and n is an integer selected from 1 to 10. In some embodiments, L and / or U are deuterated.

[0184] In some embodiments, the present disclosure provides a general formula of Ab-(LU) n In the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, Ab is an antibody or an antigen-binding fragment thereof, L is a linker, U is a camptothecin-type topoisomerase I inhibitor, n is an integer selected from 1 to 10, wherein L and / or U are deuterated, and the cytotoxic drug U is SN-38, an SN-38 derivative, exatecan, or an exatecan derivative.

[0185] In some specific embodiments, the present disclosure provides the general formula Ab-(LU) n In the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, Ab is an antibody or an antigen-binding fragment thereof, L is a linker, U is a camptothecin-type topoisomerase I inhibitor, n is an integer selected from 1-10, wherein U is deuterated, and the cytotoxic drug U is an exatecan derivative.

[0186] In some embodiments, the present disclosure provides a general formula of Ab-(LU) n In the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, -U is a structure represented by the following formula Ia:

[0187] In some embodiments, the present disclosure provides a general formula of Ab-(LU) n In the antibody-drug conjugate or its pharmaceutically acceptable salt or solvate, -L- is a structure represented by the following formula IIa:

[0188] wherein R1 and R2 are independently selected from hydrogen (H) or deuterium (D);

[0189] Furthermore, the 3-position of -(succinimidyl-3-yl-N)- in the structure shown is linked to the antibody or its antigen-binding fragment Ab, and the methylene group at the other end is linked to the cytotoxic drug U.

[0190] In some embodiments, the -L- is a structure represented by the following formula IIa-1, IIa-2, IIa-3 or IIa-4:

[0191] The 3-position of -(succinimide-3-yl-N)- in the structure shown is connected to the antibody or its antigen-binding fragment Ab, and the methylene group at the other end is connected to the cytotoxic drug U.

[0192] In some embodiments, the present disclosure provides a general formula of Ab-(LU) n In the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, the -LU is a structure represented by the following formula IIIa:

[0193] wherein R1 and R2 are independently selected from hydrogen (H) or deuterium (D).

[0194] In some embodiments, the -LU is a structure represented by the following formula IIIa-1, IIIa-2, IIIa-3 or IIIa-4:

[0195] In some embodiments, the present disclosure provides a general formula of Ab-(LU) n The antibody-drug conjugate or its pharmaceutically acceptable salt or solvate, wherein the structure of the antibody-drug conjugate is shown in the following formula IV:

[0196] Wherein, Ab is an antibody or an antigen-binding fragment thereof, n is an integer selected from 1-10, and R1 and R2 are independently selected from hydrogen (H) or deuterium (D).

[0197] In some specific embodiments, the structure of the antibody drug conjugate is shown in Formula IV-1, IV-2, IV-3 or IV-4:

[0198] Wherein, Ab is an antibody or an antigen-binding fragment thereof, and n is an integer selected from 1-10.

[0199] In some embodiments, the present disclosure provides a general formula of Ab-(LU) n The antibody-drug conjugate or its pharmaceutically acceptable salt or solvate thereof, wherein the structure of the antibody-drug conjugate is shown in Formula IV-1, wherein Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof.

[0200] In some embodiments, in the above-mentioned antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof, n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7 or 7-8. In some embodiments, n is an integer selected from 2-8, 3-8, 4-8, 5-8, 6-8 or 7-8.

[0201] In some embodiments, n is an integer selected from 2 to 8. In some embodiments, n is an integer selected from 4 to 8. In some embodiments, n is an integer selected from 6 to 8. In some embodiments, n is 6, 7, or 8. In some embodiments, n is 2, 4, 6, or 8. In some embodiments, n is 2, 4, or 8. In some embodiments, n is 4, 6, or 8. In some embodiments, n is 4 or 8. In some embodiments, n is 6 or 8.

[0202] In some embodiments, the present disclosure provides a general formula of Ab-(LU) n The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the structure of the antibody-drug conjugate is shown in Formula IV-1, wherein Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, and the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises HCDR1 shown in SEQ ID NO: 3, HCDR2 shown in SEQ ID NO: 5, HCDR3 shown in SEQ ID NO: 7, LCDR1 shown in SEQ ID NO: 8, LCDR2 shown in SEQ ID NO: 9, and LCDR3 shown in SEQ ID NO: 10. In some such embodiments, n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7 or 7-8; preferably, n is an integer selected from 4-8 or 6-8; more preferably, n is 4, 6 or 8.

[0203] In some embodiments, the present disclosure provides a general formula of Ab-(LU) nThe antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the structure of the antibody-drug conjugate is shown in Formula IV-1, wherein Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, which comprises a heavy chain variable region and a light chain variable region, and the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence shown in SEQ ID NOs: 12 and 17, respectively. In some such embodiments, n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7, or 7-8; preferably, n is an integer selected from 4-8 or 6-8; more preferably, n is 4, 6, or 8. Further, in some of these embodiments, the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises a HCDR1 set forth in SEQ ID NO: 3, a HCDR2 set forth in SEQ ID NO: 5, a HCDR3 set forth in SEQ ID NO: 7, a LCDR1 set forth in SEQ ID NO: 8, a LCDR2 set forth in SEQ ID NO: 9, and a LCDR3 set forth in SEQ ID NO: 10.

[0204] In some embodiments, the present disclosure provides a general formula of Ab-(LU) nThe antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the structure of the antibody-drug conjugate is shown in Formula IV-1, wherein Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, which comprises a heavy chain variable region and a light chain variable region, and the heavy chain variable region and the light chain variable region comprise an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence shown in SEQ ID NOs: 14 and 17, respectively. In some such embodiments, n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7, or 7-8; preferably, n is an integer selected from 4-8 or 6-8; more preferably, n is 4, 6, or 8. Further, in some of these embodiments, the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises a HCDR1 set forth in SEQ ID NO: 3, a HCDR2 set forth in SEQ ID NO: 5, a HCDR3 set forth in SEQ ID NO: 7, a LCDR1 set forth in SEQ ID NO: 8, a LCDR2 set forth in SEQ ID NO: 9, and a LCDR3 set forth in SEQ ID NO: 10.

[0205] In some embodiments, the present disclosure provides a general formula of Ab-(LU) n The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the structure of the antibody-drug conjugate is as shown in Formula IV-1, wherein Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 12, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 17. In some such embodiments, n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7, or 7-8; preferably, n is an integer selected from 4-8 or 6-8; more preferably, n is 4, 6, or 8.

[0206] In some embodiments, the present disclosure provides a general formula of Ab-(LU) nThe antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the structure of the antibody-drug conjugate is as shown in Formula IV-1, wherein Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 14, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 17. In some such embodiments, n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7, or 7-8; preferably, n is an integer selected from 4-8 or 6-8; more preferably, n is 4, 6, or 8.

[0207] In some embodiments, the present disclosure provides a general formula of Ab-(LU) n The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the structure of the antibody-drug conjugate is shown in Formula IV-1, wherein Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, comprising a heavy chain variable region and a light chain variable region, wherein the amino acid sequence of the heavy chain variable region is shown in SEQ ID NO: 12, and the amino acid sequence of the light chain variable region is shown in SEQ ID NO: 17. In some such embodiments, n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7, or 7-8; preferably, n is an integer selected from 4-8 or 6-8; more preferably, n is 4, 6, or 8.

[0208] In some embodiments, the present disclosure provides a general formula of Ab-(LU) nThe antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the structure of the antibody-drug conjugate is shown in Formula IV-1, wherein Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, comprising a heavy chain variable region and a light chain variable region, wherein the amino acid sequence of the heavy chain variable region is shown in SEQ ID NO: 14, and the amino acid sequence of the light chain variable region is shown in SEQ ID NO: 17. In some such embodiments, n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7, or 7-8; preferably, n is an integer selected from 4-8 or 6-8; more preferably, n is 4, 6, or 8.

[0209] In some embodiments, the present disclosure provides a general formula of Ab-(LU) n The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the structure of the antibody-drug conjugate is as shown in Formula IV-1, wherein Ab is an anti-CLDN18.2 antibody, which comprises a heavy chain and a light chain, the heavy chain comprising an amino acid sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identity to the amino acid sequence of SEQ ID NO: 61, and the light chain comprising an amino acid sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identity to the amino acid sequence of SEQ ID NO: 61, The amino acid sequence of NO:62 has at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identity. In some embodiments, n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7 or 7-8; preferably, n is an integer selected from 4-8 or 6-8; more preferably, n is 4, 6 or 8. Further, in some of these embodiments, the anti-CLDN18.2 antibody comprises HCDR1 set forth in SEQ ID NO:3, HCDR2 set forth in SEQ ID NO:5, HCDR3 set forth in SEQ ID NO:7, LCDR1 set forth in SEQ ID NO:8, LCDR2 set forth in SEQ ID NO:9, and LCDR3 set forth in SEQ ID NO:10.

[0210] In some embodiments, the present disclosure provides a general formula of Ab-(LU) n The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the structure of the antibody-drug conjugate is as shown in Formula IV-1, wherein Ab is an anti-CLDN18.2 antibody, which comprises a heavy chain and a light chain, the heavy chain comprising an amino acid sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identity to the amino acid sequence of SEQ ID NO: 63, and the light chain comprising an amino acid sequence having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identity to the amino acid sequence of SEQ ID NO: 63 The amino acid sequence of NO:64 has an amino acid sequence with at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identity. In some such embodiments, n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7 or 7-8; preferably, n is an integer selected from 4-8 or 6-8; more preferably, n is 4, 6 or 8. Further, in some of these embodiments, the anti-CLDN18.2 antibody comprises HCDR1 set forth in SEQ ID NO:3, HCDR2 set forth in SEQ ID NO:5, HCDR3 set forth in SEQ ID NO:7, LCDR1 set forth in SEQ ID NO:8, LCDR2 set forth in SEQ ID NO:9, and LCDR3 set forth in SEQ ID NO:10.

[0211] In some embodiments, the present disclosure provides a general formula of Ab-(LU) nThe antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the structure of the antibody-drug conjugate is as shown in Formula IV-1, wherein Ab is an anti-CLDN18.2 antibody comprising a heavy chain and a light chain, wherein the heavy chain comprises the amino acid sequence of SEQ ID NO: 61, and the light chain comprises the amino acid sequence of SEQ ID NO: 62. In some such embodiments, n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7, or 7-8; preferably, n is an integer selected from 4-8 or 6-8; more preferably, n is 4, 6, or 8.

[0212] In some embodiments, the present disclosure provides a general formula of Ab-(LU) n The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the structure of the antibody-drug conjugate is as shown in Formula IV-1, wherein Ab is an anti-CLDN18.2 antibody comprising a heavy chain and a light chain, wherein the heavy chain comprises the amino acid sequence of SEQ ID NO: 63, and the light chain comprises the amino acid sequence of SEQ ID NO: 64. In some such embodiments, n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7, or 7-8; preferably, n is an integer selected from 4-8 or 6-8; more preferably, n is 4, 6, or 8.

[0213] In some embodiments, the present disclosure provides a general formula of Ab-(LU) n The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the structure of the antibody-drug conjugate is shown in Formula IV-1, wherein Ab is an anti-CLDN18.2 antibody comprising a heavy chain and a light chain, the amino acid sequence of the heavy chain is shown in SEQ ID NO: 61, and the amino acid sequence of the light chain is shown in SEQ ID NO: 62. In some such embodiments, n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7, or 7-8; preferably, n is an integer selected from 4-8 or 6-8; more preferably, n is 4, 6, or 8.

[0214] In some embodiments, the present disclosure provides a general formula of Ab-(LU) n The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the structure of the antibody-drug conjugate is shown in Formula IV-1, wherein Ab is an anti-CLDN18.2 antibody comprising a heavy chain and a light chain, the amino acid sequence of the heavy chain is shown in SEQ ID NO: 63, and the amino acid sequence of the light chain is shown in SEQ ID NO: 64. In some such embodiments, n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7, or 7-8; preferably, n is an integer selected from 4-8 or 6-8; more preferably, n is 4, 6, or 8.

[0215] In some embodiments, the present disclosure provides an antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the antibody-drug conjugate is formed by linking the structure represented by the following formula IIIa to an antibody or an antigen-binding fragment thereof:

[0216] Wherein, R1 and R2 are independently selected from hydrogen (H) or deuterium (D), and the 3-position of -(succinimidyl-3-yl-N)- in the structure represented by Formula IIIa is linked to an antibody or antigen-binding fragment thereof. In some specific embodiments, the antibody-drug conjugate is formed by linking the structure represented by Formula IIIa to an antibody or antigen-binding fragment thereof via a thioether bond. In some specific embodiments, the antibody or antigen-binding fragment thereof is an anti-CLDN18.2 antibody or antigen-binding fragment thereof disclosed herein.

[0217] In some embodiments, the present disclosure provides an antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the antibody-drug conjugate is formed by linking the structure represented by the following formula IIIa-1 to an antibody or an antigen-binding fragment thereof.

[0218] The 3-position of -(succinimidyl-3-yl-N)- in the structure represented by Formula IIIa-1 is linked to an antibody or its antigen-binding fragment. In some specific embodiments, the antibody-drug conjugate is formed by linking the structure represented by Formula IIIa-1 to an antibody or its antigen-binding fragment via a thioether bond. In some specific embodiments, the antibody or its antigen-binding fragment is an anti-CLDN18.2 antibody or its antigen-binding fragment disclosed herein.

[0219] In some specific embodiments, the present disclosure provides an antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the antibody-drug conjugate is formed by linking the structure represented by the following formula IIIa-1 to an antibody or an antigen-binding fragment thereof.

[0220] Wherein, the 3-position of -(succinimide-3-yl-N)- in the structure represented by Formula IIIa-1 is linked to an antibody or an antigen-binding fragment thereof; the antibody or antigen-binding fragment thereof is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, which comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3, wherein HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise the amino acid sequences represented by SEQ ID NOs: 3, 5, 7, 8, 9 and 10, respectively. Further, in some specific embodiments, the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises a heavy chain variable region and a light chain variable region, wherein: (1) the heavy chain variable region comprises an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence of SEQ ID NO: 12, and the light chain variable region comprises an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence of SEQ ID NO: NO:17 has an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence of SEQ ID NO:17; or (2) the heavy chain variable region comprises an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence of SEQ ID NO:14, and the light chain variable region comprises an amino acid sequence that is at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the amino acid sequence of SEQ ID NO:14 The amino acid sequence of NO: 17 has at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identity. In some specific embodiments, the antibody-drug conjugate is formed by linking the structure of Formula IIIa-1 to an antibody or antigen-binding fragment thereof via a thioether bond.

[0221] In one aspect, the present disclosure provides a general formula of Ab-(LU) nThe antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof exhibits one or more of the following properties:

[0222] (a) Binding to CLDN18.2;

[0223] (b) blocking the binding of CLDN18.2 to its ligand;

[0224] (c) Demonstrates endocytosis in cells expressing CLDN18.2;

[0225] (d) has cytotoxic activity against tumor cells expressing CLDN18.2;

[0226] (e) has a bystander effect;

[0227] (f) having ADCC activity;

[0228] (g) having CDC activity;

[0229] (h) does not bind to CLDN18.1;

[0230] (i) does not bind to cells that do not express CLDN18.2;

[0231] (j) No ADCC and / or CDC activity against cells expressing CLDN18.1.

[0232] In some embodiments, the antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof has properties (a)-(j). In some embodiments, the antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof has properties (a) and (c)-(j).

[0233] In some embodiments, the antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof binds to human CLDN18.2. In some embodiments, the antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof does not bind to human CLDN18.1.

[0234] In some embodiments, the antibody drug conjugates provided herein, or pharmaceutically acceptable salts or solvates thereof, show strong endocytosis in cells expressing different CLDN18.2 levels, and can continuously accumulate the amount of internalized ADC as the endocytosis time increases.

[0235] Pharmaceutical composition

[0236] In one aspect, the present disclosure provides a pharmaceutical composition comprising an antibody drug conjugate of the present disclosure or a pharmaceutically acceptable salt or solvate thereof. In some embodiments, the present disclosure provides a pharmaceutical composition comprising an antibody drug conjugate according to the present disclosure or a pharmaceutically acceptable salt or solvate thereof, and a pharmaceutically acceptable carrier. Pharmaceutically acceptable carriers include, for example, excipients, diluents, encapsulating materials, fillers, buffers, or other agents.

[0237] The number of cytotoxic drugs conjugated to the antibody or antigen-binding fragment thereof in the antibody-drug conjugates of the present disclosure can vary, so that the antibody-drug conjugates or pharmaceutically acceptable salts or solvates thereof in the pharmaceutical compositions provided herein can be heterogeneous or homogeneous. Heterogeneous means that the pharmaceutical composition includes antibody-drug conjugates containing different numbers of cytotoxic drugs, for example, antibody-drug conjugates in which one molecule of antibody or antigen-binding fragment thereof is conjugated to 0 (i.e., no cytotoxic drug), 1, 2, 3, 4, 5, 6, 7, 8, or more molecules of cytotoxic drug. Antibody-drug conjugates in which one molecule of antibody or antigen-binding fragment thereof is linked to 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9 molecules of cytotoxic drug are referred to as D0, D1, D2, D3, D4, D5, D6, D7, D8, or D9, respectively.

[0238] By controlling the ratio of antibody-drug conjugates containing different numbers (n) of cytotoxic drugs in the above-mentioned pharmaceutical composition, pharmaceutical compositions containing ADCs with different drug-antibody ratios (DARs) can be produced. It should be understood that the DAR is the average number of cytotoxic drug conjugates per molecule of antibody or its antigen-binding fragment in the pharmaceutical composition. For example, "DAR of about 4" refers to a pharmaceutical composition comprising a heterogeneous mixture of ADCs in which each molecule of antibody or its antigen-binding fragment is conjugated to the same or different numbers of cytotoxic drugs (e.g., each antibody or its antigen-binding fragment is conjugated to 0, 1, 2, 3, 4, 5, 6, 7 or 8 cytotoxic drugs), but the average number of cytotoxic drug conjugates per molecule of antibody or its antigen-binding fragment is about 4. Similarly, "DAR of about 8" refers to the average number of cytotoxic drug conjugates per molecule of antibody or its antigen-binding fragment in the pharmaceutical composition is about 8.

[0239] In some embodiments, the pharmaceutical composition has a DAR of 0-10, 0-9, 0-8, 1-10, 1-9, 1-8, 2-10, 2-9, 2-8, 3-8, 4-8, 5-8, 6-8, 7-8, 7.2-8, 7.4-8, 7.5-8, 7.6-8, 7.7-8, 7.8-8, 7.8-7.9, or 7.9- 8. In some embodiments, the pharmaceutical composition has a DAR of about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 7.1, about 7.2, about 7.3, about 7.4, about 7.5, about 7.6, about 7.7, about 7.8, about 7.9, or about 8.0.

[0240] In some embodiments, the pharmaceutical composition has a DAR of 7-8, 7.2-8, 7.4-8, 7.6-8, or 7.7-8. In some embodiments, the pharmaceutical composition has a DAR of about 7.1, about 7.2, about 7.4, about 7.6, about 7.7, or about 8.

[0241] In some embodiments, the antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof in the pharmaceutical composition is heterogeneous, and the distribution of each antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof with different amounts of cytotoxic drugs is as follows: D0-D7 accounts for 0%-30%, D8 is 60%-100%, and D9 and above is 0%-15%; in some alternative embodiments, D0-D3 is 0% to 10%, D4-D7 is 0%-30%, D8 is 60%-100%, and D9 is 0%-15%. In some alternative embodiments, D0-D6 is 0% to 30%, D7-D8 is 60% to 100%, and D9 and above is 0% to 15%; in some alternative embodiments, D0-D5 is 0% to 30%, D6-D8 is 70% to 100%, and D9 and above is 0% to 15%; in some alternative embodiments, D0 is 0% to 10%, D1 is 0% to 10%, D2 is 0% to 10%, D3 is 0% to 10%, D4 is 0% to 20%, D In some alternative embodiments, D0 is 0% to 6%, D1 is 0% to 6%, D2 is 0% to 6%, D3 is 0% to 6%, D4 is 0%-15%, D5 is 0% to 6%, D6 is 0% to 20%, D7 is 0%-6%, D8 is 60%-100%, and D9 or more is 0%-10%; in some alternative embodiments, D0 is 0% to 6%, D1 is 0% to 6%, D2 is 0% to 6%, D3 is 0% to 6%, D4 is 0%-15%, D5 is 0% to 6%, D6 is 0% to 20%, D7 is 0%-6%, D8 is 60%-100%, and D9 or more is 0%-10%; in some alternative embodiments, D0 is In some alternative embodiments, D0 is 0% to 5%, D1-D3 is 0% to 5%, D4 is 0%-15%, D5-D7 is 0%-20%, D8 is 60%-100%, and D9 or more is 0%-10%; the distribution ratio of each antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof is based on molar amount.

[0242] use

[0243] The present disclosure provides uses of the antibody-drug conjugate of the present disclosure or a pharmaceutically acceptable salt or solvate thereof, or the pharmaceutical composition of the present disclosure.

[0244] In one aspect, the present disclosure provides the use of the antibody drug conjugate of the present disclosure or its pharmaceutically acceptable salt or solvate in the preparation of a medicament for treating tumors. In one aspect, the present disclosure provides the use of the antibody drug conjugate of the present disclosure or its pharmaceutically acceptable salt or solvate in the treatment of tumors. In one aspect, the present disclosure provides the use of the pharmaceutical composition of the present disclosure in the preparation of a medicament for treating tumors. In one aspect, the present disclosure provides the use of the pharmaceutical composition of the present disclosure in the treatment of tumors.

[0245] In one aspect, the present disclosure provides the use of an antibody drug conjugate of the present disclosure or a pharmaceutically acceptable salt or solvate thereof and a second or additional therapeutic agent in the preparation of a medicament for treating a tumor. In one aspect, the present disclosure provides the use of an antibody drug conjugate of the present disclosure or a pharmaceutically acceptable salt or solvate thereof and a second or additional therapeutic agent in the treatment of a tumor. In one aspect, the present disclosure provides the use of a pharmaceutical composition of the present disclosure and a second or additional therapeutic agent in the preparation of a medicament for treating a tumor. In one aspect, the present disclosure provides the use of a pharmaceutical composition of the present disclosure and a second or additional therapeutic agent in the treatment of a tumor.

[0246] In one aspect, the present disclosure provides an antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof, or a pharmaceutical composition thereof for treating tumors. In one aspect, the present disclosure provides an antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof, or a pharmaceutical composition thereof, for treating tumors in combination with a second or additional therapeutic agent.

[0247] In one aspect, the present disclosure provides a method for treating a tumor, comprising administering an antibody drug conjugate of the present disclosure or a pharmaceutically acceptable salt or solvate thereof to a subject. In one aspect, the present disclosure provides a method for treating a tumor, comprising administering a therapeutically effective amount of an antibody drug conjugate of the present disclosure or a pharmaceutically acceptable salt or solvate thereof to a subject in need thereof. In one aspect, the present disclosure provides a method for treating a tumor, comprising administering a pharmaceutical composition of the present disclosure to a subject in need thereof. In one aspect, the present disclosure provides a method for treating a tumor, comprising administering a therapeutically effective amount of a pharmaceutical composition of the present disclosure to a subject in need thereof. In some embodiments, the method comprises contacting tumor cells with the antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof, or the pharmaceutical composition, thereby killing tumor cells or inhibiting tumor cell growth.

[0248] In one aspect, the present disclosure provides a method for treating a tumor, comprising administering an antibody drug conjugate of the present disclosure, or a pharmaceutically acceptable salt or solvate thereof, and a second or additional therapeutic agent to a subject. In one aspect, the present disclosure provides a method for treating a tumor, comprising administering a therapeutically effective amount of an antibody drug conjugate of the present disclosure, or a pharmaceutically acceptable salt or solvate thereof, and a second or additional therapeutic agent to a subject in need. In one aspect, the present disclosure provides a method for treating a tumor, comprising administering a pharmaceutical composition of the present disclosure and a second or additional therapeutic agent to a subject in need. In one aspect, the present disclosure provides a method for treating a tumor, comprising administering a therapeutically effective amount of a pharmaceutical composition of the present disclosure and a second or additional therapeutic agent to a subject in need. In some embodiments, the method comprises contacting tumor cells with the antibody drug conjugate, or a pharmaceutically acceptable salt or solvate thereof, or the pharmaceutical composition, and simultaneously or sequentially contacting the tumor cells with a second or additional therapeutic agent, thereby killing the tumor cells or inhibiting tumor cell growth.

[0249] In some embodiments, administering the antibody drug conjugate of the present disclosure or its pharmaceutically acceptable salt or solvate to a subject can kill tumor cells or inhibit tumor cell growth. In some embodiments, administering a therapeutically effective amount of the antibody drug conjugate of the present disclosure or its pharmaceutically acceptable salt or solvate to a subject can kill tumor cells or inhibit tumor cell growth. In some embodiments, administering a pharmaceutical composition of the present disclosure to a subject can kill tumor cells or inhibit tumor cell growth. In some embodiments, administering a therapeutically effective amount of the pharmaceutical composition of the present disclosure to a subject can kill tumor cells or inhibit tumor cell growth.

[0250] In some embodiments, administering an antibody drug conjugate of the present disclosure, or a pharmaceutically acceptable salt or solvate thereof, and a second or additional therapeutic agent to a subject can kill tumor cells or inhibit tumor cell growth. In some embodiments, administering a therapeutically effective amount of an antibody drug conjugate of the present disclosure, or a pharmaceutically acceptable salt or solvate thereof, and a second or additional therapeutic agent to a subject can kill tumor cells or inhibit tumor cell growth. In some embodiments, administering a pharmaceutical composition of the present disclosure, and a second or additional therapeutic agent to a subject can kill tumor cells or inhibit tumor cell growth. In some embodiments, administering a pharmaceutical composition of the present disclosure, and a second or additional therapeutic agent to a subject can kill tumor cells or inhibit tumor cell growth.

[0251] In the above-mentioned method or use, the pharmaceutical composition comprises the antibody-drug conjugate of the present disclosure or a pharmaceutically acceptable salt or solvate thereof; optionally, further comprises a pharmaceutically acceptable carrier.

[0252] In some embodiments, in the above methods or uses, the tumor is a CLDN18.2-positive tumor. In some embodiments, administering a therapeutically effective amount of an antibody-drug conjugate of the present disclosure, or a pharmaceutically acceptable salt or solvate thereof, or a pharmaceutical composition of the present disclosure to a subject can kill tumor cells expressing CLDN18.2 or inhibit the growth of tumor cells expressing CLDN18.2. Examples of tumors include, but are not limited to, gastric cancer, esophageal cancer, gastrointestinal cancer (including colon cancer and rectal cancer), pancreatic cancer, liver cancer, lung cancer (including small cell lung cancer and non-small cell lung cancer), bronchial cancer, mesothelioma, kidney cancer, ovarian cancer (including Krugenberg tumor), breast cancer, bladder cancer, uterine cancer, endometrial cancer, prostate cancer, testicular cancer, anal cancer, vaginal cancer, bile duct cancer, gallbladder cancer, head and neck cancer, spinal tumors, otolaryngology tumors, thyroid cancer, mesothelioma, bone cancer, skin cancer, melanoma, adenocarcinoma, sarcoma, neuroblastoma, glioblastoma, brain cancer, central nervous system cancer, neuroendocrine tumors, leukemia, lymphoma, and myeloma.

[0253] Reagent test kit

[0254] The present disclosure provides a kit comprising the anti-CLDN18.2 antibody-drug conjugate of the present disclosure or a pharmaceutically acceptable salt or solvate thereof, or the pharmaceutical composition of the present disclosure.

[0255] The present disclosure describes a kit comprising the anti-CLDN18.2 antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, or the pharmaceutical composition. The kit can be used to implement the uses or other uses of the anti-CLDN18.2 antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, or the pharmaceutical composition provided herein. In some embodiments, the kit can include the anti-CLDN18.2 antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, or the pharmaceutical composition. The kit can also include instructions for use. The kit can also include other materials required from a commercial and user perspective, such as other buffers, diluents, needles, syringes, etc.

[0256] Cytotoxic drugs and linker-payloads

[0257] In some aspects, the present disclosure provides a linker-payload having a structure shown in Formula III below:

[0258] Wherein, R1 and R2 are independently selected from hydrogen (H) or deuterium (D).

[0259] In some specific embodiments, the present disclosure provides a linker-payload having a structure shown in Formula III-1, III-2, III-3, or III-4 below,

[0260] The linker-payload is used to obtain an antibody-drug conjugate formed by connecting an antibody or an antigen-binding fragment thereof to the linker-payload.

[0261] In some aspects, the present disclosure provides compounds having the structure shown in Formula I below,

[0262] The antibody-drug conjugates or pharmaceutically acceptable salts or solvates thereof provided herein achieve excellent anti-tumor effects and / or safety. In some embodiments, the anti-CLDN18.2 antibody-drug conjugates provided exhibit good cytotoxicity against a variety of tumor cells expressing CLDN18.2. In some embodiments, the anti-CLDN18.2 antibody-drug conjugates provided have no cytotoxicity against cells expressing CLDN18.1. In some embodiments, the anti-CLDN18.2 antibody-drug conjugates provided effectively bind to cells expressing CLDN18.2 and effectively endocytose in cells expressing CLDN18.2. In some embodiments, the anti-CLDN18.2 antibody-drug conjugates provided have good in vivo anti-tumor activity. In some embodiments, the anti-CLDN18.2 antibody-drug conjugates provided have excellent safety. In some embodiments, the anti-CLDN18.2 antibody-drug conjugates provided are not susceptible to aggregation.

[0263] The antibody drug conjugates or pharmaceutically acceptable salts or solvates thereof provided herein have excellent pharmacokinetic properties, which can lead to lower toxicity, higher safety and / or tolerability, higher efficacy, and a wider therapeutic window.

[0264] Preparation method

[0265] The present disclosure provides a method for preparing an antibody-drug conjugate of the present disclosure or a pharmaceutically acceptable salt or solvate thereof, comprising treating an anti-CLDN18.2 antibody or an antigen-binding fragment thereof under reducing conditions, and then reacting the anti-CLDN18.2 antibody or the antigen-binding fragment thereof with a linker-payload selected from the structure represented by Formula III, wherein R1 and R2 are each independently selected from hydrogen or deuterium. In some embodiments, R1 and R2 are hydrogen.

[0266] In some embodiments, the method comprises treating an anti-CLDN18.2 antibody or an antigen-binding fragment thereof under reducing conditions, followed by reacting the anti-CLDN18.2 antibody or antigen-binding fragment thereof with a linker-payload having the structure represented by Formula III-1. In some embodiments, the method comprises reducing the anti-CLDN18.2 antibody or antigen-binding fragment thereof in the presence of TCEP, followed by mixing the anti-CLDN18.2 antibody or antigen-binding fragment thereof with a linker-payload having the structure represented by Formula III-1 to perform a conjugation reaction, thereby obtaining the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0267] Figures 1A-1C show the binding activity of hz28G3-1.1-DDDXd (DAR of 7.4), hz28G3-1.3-DDDXd (DAR of 7.6), hz28G3-1.1, and hz28G3-1.3 to NIH-3T3, BxPC-3, and NCI-N87 cells overexpressing CLDN18.2;

[0268] Figures 2A-2D show the endocytosis of hz28G3-1.1-DDDXd (DAR of 7.4), hz28G3-1.3-DDDXd (DAR of 7.6), hz28G3-1.1, and hz28G3-1.3 in CLDN18.2-overexpressing NIH-3T3, BxPC-3, NCI-N87 cells, and the CLDN18.2-positive natural cell line NUGC-4;

[0269] Figures 3A-3C show the killing effect of hz28G3-1.1-DDDXd (DAR of 7.4) and hz28G3-1.3-DDDXd (DAR of 7.6) on NIH-3T3, BxPC-3, and NCI-N87 cells overexpressing CLDN18.2;

[0270] Figure 4 shows the CDC activity of hz28G3-1.1-DDDXd (DAR of 7.4) and hz28G3-1.3-DDDXd (DAR of 7.6) on NIH-3T3 cells overexpressing CLDN18.2;

[0271] Figure 5 shows the nonspecific killing of NIH-3T3-CLDN18.1 cells by hz28G3-1.1-DDDXd (DAR of 7.4) and hz28G3-1.3-DDDXd (DAR of 7.6);

[0272] Figure 6 shows the bystander effect of hz28G3-1.1-DDDXd (DAR of 7.4) and hz28G3-1.3-DDDXd (DAR of 7.6), where BxPC-3 cells overexpressing CLDN18.2 are used as positive cells and U2OS-Luciferase is used as negative cells.

[0273] Explanation and Definition

[0274] Unless otherwise indicated, the following terms used in this disclosure have the following meanings. A particular term should not be construed as undefined or unclear unless specifically defined, but rather should be understood according to its ordinary meaning in the art. When a trade name appears herein, it is intended to refer to the corresponding commercial product or its active ingredient.

[0275] The term "substituted" refers to the replacement of any one or more hydrogen atoms on a particular atom by a substituent, as long as the valence state of the particular atom is normal and the substituted compound is stable. When the substituent is an oxo (i.e., =O), it means that two hydrogen atoms are replaced. Oxo does not occur on aromatic groups.

[0276] When any variable (e.g., R) occurs more than once in a compound's composition or structure, its definition on each occurrence is independent. Thus, for example, if a group is substituted with two R's, each R has an independent alternative.

[0277] As used herein, the structure of "-(succinimidyl-3-yl-N)-" is as follows:

[0278] Unless otherwise specified, use a solid wedge key. and dotted wedge key Indicates the absolute configuration of a stereocenter.

[0279] Unless otherwise specified, when a group has a linkable site, the bond connecting that site to another group is represented by a wavy line. For example, It means that the nitrogen atom at position 1 and the carbon atom at position 3 of the -(succinimide-3-yl-N)- group are connected to other groups.

[0280] "Derivative": A compound formed by replacing atoms or atomic groups in the parent compound molecule with other atoms or atomic groups is called a derivative of the parent compound.

[0281] The compounds and intermediates of the present disclosure may also exist in different tautomeric forms, and all such forms are included within the scope of the present disclosure. The term "tautomer" or "tautomeric form" refers to structural isomers of different energies that can interconvert via a low energy barrier. For example, proton tautomers (also known as prototropic tautomers) include interconversions via proton migration, such as keto-enol and imine-enamine isomerizations. A specific example of a proton tautomer is the imidazole moiety, in which a proton can migrate between two ring nitrogens. Valence tautomers include interconversions by reorganization of some bonding electrons.

[0282] The compounds of the present invention may be asymmetric, for example, having one or more stereoisomers. The compounds of the present invention may also exist as specific geometric isomers. Unless otherwise indicated, all geometric isomers and stereoisomers are included, such as cis and trans isomers, levorotatory and dextrorotatory isomers, enantiomers, diastereoisomers (D)-isomers and (L)-isomers. Racemic mixtures and other mixtures of the above-mentioned isomers, such as mixtures enriched in enantiomers or diastereomers, also fall within the scope of the present invention. The compounds of the present invention containing asymmetric carbon atoms can be isolated in optically pure form or racemic form. Optically pure forms can be resolved from racemic mixtures or synthesized by using chiral raw materials or chiral reagents.

[0283] Unless otherwise indicated, the terms "cis-trans isomers" or "geometric isomers" refer to stereoisomers that are mirror images of one another. Unless otherwise indicated, the term "diastereomers" refers to stereoisomers that have two or more chiral centers and are not mirror images of one another.

[0284] Unless otherwise specified, those skilled in the art will understand that D in the structural formulas disclosed herein is equivalent to deuterium.

[0285] The term "bystander effect" as used herein refers to an effect in which a cytotoxic drug coupled to an antibody or antigen-binding fragment thereof by a cleavable or non-cleavable linker has the ability to diffuse across the cell membrane after release from the antibody or antigen-binding fragment thereof, thereby causing killing of adjacent cells. The ability to diffuse across the cell membrane is related to the hydrophobicity of the cytotoxic drug or the combination of the cytotoxic drug and the linker. Such cytotoxic drugs may, for example, be exatecan derivatives or MMAE. In particular, in tumors with heterogeneous target expression and solid tumors where antibody penetration may be limited, a bystander effect may be desirable.

[0286] The term "treating" means administering a compound or pharmaceutical composition of the present disclosure to prevent, ameliorate, or eliminate a disease or one or more symptoms associated with the disease, and includes, but is not limited to: (i) preventing the occurrence of a disease or disease state in a mammal, particularly when such mammal is susceptible to the disease state but has not yet been diagnosed as having the disease state; (ii) inhibiting the disease or disease state, i.e., curbing its development; (iii) relieving the disease or disease state, i.e., causing the disease or disease state to regress; and (iv) reducing any direct or indirect pathological consequences of the disease or disease state.

[0287] The term "therapeutically effective amount" means an amount of a compound of the present disclosure that (i) treats or prevents a specific disease, condition, or disorder, (ii) alleviates, ameliorates, or eliminates one or more symptoms of a specific disease, condition, or disorder, or (iii) prevents or delays the onset of one or more symptoms of a specific disease, condition, or disorder described herein. The amount of a compound of the present disclosure or pharmaceutical composition that constitutes a "therapeutically effective amount" may vary depending on factors such as the compound or pharmaceutical composition and its ability to elicit a desired response in a subject, the disease state and its severity, the route of administration, and the age, sex, and weight of the mammal to be treated.

[0288] The term "pharmaceutically acceptable" refers to those compounds, materials, compositions and / or dosage forms that are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response or other problems or complications, commensurate with a reasonable benefit / risk ratio.

[0289] The term "pharmaceutically acceptable salt" refers to a salt of a compound (e.g., the antibody-drug conjugates of the present disclosure) that is safe and effective when used in mammals and has the desired biological activity. For example, the salt may be a metal salt, an ammonium salt, a salt formed with an organic base, a salt formed with an inorganic acid, a salt formed with an organic acid, a salt formed with a basic or acidic amino acid, etc.

[0290] The term "solvate" refers to an association of a compound with solvent molecules.

[0291] The term "antibody" is used in the broadest sense and includes, but is not limited to, various antibody structures including monoclonal antibodies, polyclonal antibodies, and multispecific antibodies (eg, bispecific antibodies, trispecific antibodies), so long as they exhibit the desired antigen-binding activity.

[0292] An "antigen-binding fragment" of an antibody refers to one or more fragments of an antibody that retain the function of specifically binding to an antigen (e.g., CLDN18.2 protein). It has been demonstrated that the antigen-binding function of an antibody can be implemented by a fragment of a full-length antibody. Examples encompassed by the term "antigen-binding fragment" of an antibody include: (i) a Fab fragment: a monovalent fragment consisting of a VL, VH, CL, and CH1 domain; (ii) a F(ab')2 fragment, a bivalent fragment comprising two Fab fragments linked by a disulfide bridge at the hinge region; (iii) an Fd fragment consisting of a VH and CH1 domain; (iv) an Fv fragment consisting of the VL and VH domains of a single antibody arm; (v) a dAb fragment consisting of a VH domain (see Ward et al., Nature. 341: 544-546 (1989)); and (vi) a nanobody, an antibody comprising a single variable domain and two constant domains. In addition, although the two domains VL and VH of the Fv fragment are encoded by different genes, VH and VL can be connected into a single protein chain by a recombinant method through a linker, wherein VL and VH are paired to form a monovalent molecule called single-chain Fv (scFv) (see Bird et al., Science. 242: 423-426 (1988); Huston et al., Proc. Natl. Acad. Sci. 85: 5879-5883 (1988)), and these single-chain antibodies are also encompassed by the term antigen-binding fragment. These antibody fragments can be obtained by conventional techniques known to those skilled in the art, and the fragments can be functionally screened by the same method as full-length antibodies.

[0293] The anti-CLDN18.2 antibodies or antigen-binding fragments thereof disclosed herein may be of the IgG1, IgG2, IgG3, or IgG4 isotype. The term "isotype" refers to the class of antibodies encoded by the heavy chain constant region gene. In some embodiments, the anti-CLDN18.2 antibodies or antigen-binding fragments thereof disclosed herein are of the IgG1 isotype. The anti-CLDN18.2 antibodies or antigen-binding fragments thereof disclosed herein may be derived from any species, including but not limited to mice, rats, rabbits, non-human primates (such as chimpanzees, cynomolgus monkeys, spider monkeys, macaques), llamas, and humans. The anti-CLDN18.2 antibodies or antigen-binding fragments thereof disclosed herein may be murine antibodies, chimeric antibodies, humanized antibodies, or human antibodies.

[0294] The term "mouse antibody" or "murine antibody" refers to an antibody in which the framework region and CDR region in the variable region are both derived from mouse germline immunoglobulin sequences. In addition, if the antibody comprises a constant region, the constant region is also derived from mouse germline immunoglobulin sequences. The murine antibodies of the present disclosure may include amino acid residues that are not encoded by mouse germline immunoglobulin sequences (e.g., mutations introduced by random mutations or point mutations in vitro or by somatic mutations in vivo), but "mouse antibody" or "murine antibody" does not include antibodies in which CDR sequences derived from other mammalian germlines are inserted into mouse framework sequences.

[0295] Chimeric antibodies are antibodies created by fusing the variable region of a mouse antibody with the constant region of a human antibody. These antibodies can mitigate the immune response induced by mouse antibodies. To create chimeric antibodies, one must first establish a hybridoma that secretes mouse-specific monoclonal antibodies. The variable region genes are then cloned from the hybridoma cells. Furthermore, the constant region genes of human antibodies are cloned as needed. The mouse variable region genes and human constant region genes are then linked to form a chimeric gene, which is then inserted into an expression vector. Finally, the chimeric antibody is expressed in a eukaryotic or prokaryotic system.

[0296] A "humanized antibody" is an antibody that contains complementarity determining regions (CDRs) derived from a non-human antibody and a framework region and constant region derived from a human antibody. For example, the humanized antibodies that bind to CLDN18.2 in the antibody-drug conjugates provided herein may contain CDRs derived from one or more murine antibodies, as well as human framework regions and human constant regions. Thus, in some embodiments, the humanized antibodies in the antibody-drug conjugates provided herein bind to the same epitope on CLDN18.2 as the murine antibody from which the CDRs of the antibodies are derived. Exemplary humanized antibodies are provided herein. Additional humanized antibodies that bind to CLDN18.2, or variants thereof, comprising the heavy chain CDRs and light chain CDRs provided herein, can be generated using any human framework sequence and are also encompassed by the present disclosure. In some embodiments, framework sequences suitable for use in the present disclosure include those that are structurally similar to the framework sequences provided herein. Additional modifications may be made in the framework regions to alter the properties of the antibodies provided herein. Such additional framework modifications may include chemical modifications, point mutations to reduce immunogenicity or remove T cell epitopes, or backmutations to residues in the original germline sequence. In some embodiments, such additional modifications include those corresponding to the mutations exemplified herein, including back mutations to germline sequences. For example, in some embodiments, one or more amino acids in the human framework regions of the VH and / or VL of the humanized antibodies provided herein are backmutated to the corresponding amino acids in the parent murine antibody. In the present disclosure, humanized antibodies are also denoted as "hz".

[0297] The term “CDR” (complementarity determining region), also known as “hypervariable region.” Natural four-chain antibodies typically contain six CDRs, three in the heavy chain variable region and three in the light chain variable region.

[0298] The term "variable region" refers to the domain of about 100 to 110 or more amino acids defined by the N-terminal domain of the light or heavy chain of an antibody that is primarily responsible for antigen recognition. The terms light chain variable region (VL) and heavy chain variable region (VH) refer to these light chain domains and heavy chain domains, respectively.

[0299] As used herein, the term "EC 50 ” refers to the effective concentration that elicits 50% of the maximal response of an antibody or antigen-binding fragment thereof, or ADC; the term “IC 50 ” refers to the inhibitory concentration that elicits 50% of the maximal response of an antibody or antigen-binding fragment thereof, or ADC. EC 50 and IC 50 Measurement can be performed by ELISA or FACS analysis or any other method known in the art.

[0300] “K D ” refers to the equilibrium dissociation constant, which is obtained from K d K a (i.e., K d / K a ) and expressed as molar concentration (M). D The K value can be determined using methods well established in the art. D A preferred method is by using surface plasmon resonance technology, preferably using a biosensor system such as Surface plasmon resonance system analysis.

[0301] The term "identity" is also known as consistency. The "percentage (%) identity" of an amino acid sequence refers to the percentage of amino acid residues in the sequence to be aligned that are identical to the amino acid residues in the specific amino acid sequence shown in this article, after aligning the sequence to be aligned and, if necessary, introducing gaps to achieve maximum sequence identity, and not considering any conservative substitutions as part of sequence identity. The alignment of amino acid sequences for identity can be performed in a variety of ways within the scope of the art, such as BLAST, BLAST-2, ALIGN or Megalign (DNASTAR) software. Those skilled in the art can determine the appropriate parameters for aligning sequences, including any algorithm needed to obtain maximum alignment over the full length of the comparison sequence.

[0302] The term "X" and "Xaa" herein are equivalent and refer to unspecified amino acids. The scope of the term is specified by the definition in the relevant expression. In order to distinguish multiple "X" in the same amino acid sequence, the multiple Xs that appear successively are numbered separately (i.e., written as X n ) and define the scope they cover respectively.

[0303] The term "subject" includes any human or non-human animal. The term "non-human animal" includes all vertebrates, e.g., mammals and non-mammals, such as non-human primates, sheep, goats, dogs, cats, horses, cows, chickens, amphibians, reptiles, etc. Preferably, the subject according to the present disclosure is a human. Unless otherwise indicated, the terms "patient" or "subject" can be used interchangeably. "Subjects in need thereof" include those who already have a disease or condition, those who are at risk of developing a disease or condition, and those who may develop a disease or condition and for which the purpose is to prevent, delay, or attenuate the disease or condition.

[0304] As used herein, "about" means within the acceptable error range for a particular value as determined by one of ordinary skill in the art, which depends in part on how the value is measured or determined, i.e., the limitations of the measurement system. For example, "about" can mean within 1 or more than 1 standard deviation as practiced in the art. Alternatively, "about" can mean a range of up to ±5%, for example, fluctuations within ±2%, within ±1%, or within ±0.5% of the specific numerical range given. When a specific value is given in the scope of the present disclosure, unless otherwise indicated, the meaning of "about" should be considered to be within the acceptable error range for that specific value. In this document, unless otherwise indicated, the values ​​of step parameters or conditions are modified by "about" by default.

[0305] The terms "comprise," "comprises," or "comprising" and their equivalents (for example, contain, contains, containing, include, includes, and including) should be understood as "including but not limited to," meaning that in addition to the listed elements, components, and steps, other unspecified elements, components, and steps may also be included.

[0306] In this document, unless the context clearly indicates otherwise, singular terms include plural referents and vice versa. Similarly, the word "or" is intended to include "and" unless the context clearly indicates otherwise. DETAILED DESCRIPTION

[0307] The present disclosure also provides the following specific implementation schemes, but the protection scope of the present disclosure is not limited thereto:

[0308] Embodiment 1. A general formula is Ab-(LU) n The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein Ab is an antibody or an antigen-binding fragment thereof, L is a linker, U is a cytotoxic drug, and n is an integer selected from 1-10, wherein Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, which comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3, wherein,

[0309] (1) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 11, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 11, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 11, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 16, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 16, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 16;

[0310] (2) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 12, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 12, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 12, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 17, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 17, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 17;

[0311] (3) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 13, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 13, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 13, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 17, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 17, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 17;

[0312] (4) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 14, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 14, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 14, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 17, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 17, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 17;

[0313] (5) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 15, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 15, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 15, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 17, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 17, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 17;

[0314] (6) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 12, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 12, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 12, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 18, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 18, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 18;

[0315] (7) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 13, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 13, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 13, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 18, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 18, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 18;

[0316] (8) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 14, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 14, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 14, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 18, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 18, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 18;

[0317] (9) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 15, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 15, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 15, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 18, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 18, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 18;

[0318] (10) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 29, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 29, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 29, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 34, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 34, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 34;

[0319] (11) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 30, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 30, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 30, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 35, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 35, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 35;

[0320] (12) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 31, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 31, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 31, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 35, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 35, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 35;

[0321] (13) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 32, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 32, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 32, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 35, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 35, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 35;

[0322] (14) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 33, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 33, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 33, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 35, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 35, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 35;

[0323] (15) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 30, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 30, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 30, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 36, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 36, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 36;

[0324] (16) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 31, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 31, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 31, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 36, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 36, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 36;

[0325] (17) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 32, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 32, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 32, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 36, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 36, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 36;

[0326] (18) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 33, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 33, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 33, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 36, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 36, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 36;

[0327] (19) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 43, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 43, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 44, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 44, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 44;

[0328] (20) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 51, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 51, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 52, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 52, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 52; or

[0329] (21) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 59, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 59, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 59, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 60, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 60, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 60.

[0330] Embodiment 2. The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to embodiment 1, wherein:

[0331] (1) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 3, 4, 7, 8, 9, and 10, respectively;

[0332] (2) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 3, 5, 7, 8, 9, and 10, respectively;

[0333] (3) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 3, 6, 7, 8, 9, and 10, respectively;

[0334] (4) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 20, 24, 25, 26, and 27, respectively;

[0335] (5) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 21, 24, 25, 26, and 27, respectively;

[0336] (6) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 22, 24, 25, 26, and 27, respectively;

[0337] (7) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 23, 24, 25, 26, and 27, respectively;

[0338] (8) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 20, 24, 25, 26, and 28, respectively;

[0339] (9) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 21, 24, 25, 26, and 28, respectively;

[0340] (10) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 22, 24, 25, 26, and 28, respectively;

[0341] (11) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences of SEQ ID NOs: 19, 23, 24, 25, 26, and 28, respectively;

[0342] (12) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 37, 38, 39, 40, 41, and 42, respectively;

[0343] (13) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise the amino acid sequences of SEQ ID NOs: 45, 46, 47, 48, 49 and 50, respectively; or

[0344] (14) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise the amino acid sequences shown in SEQ ID NOs: 53, 54, 55, 56, 57 and 58, respectively.

[0345] Embodiment 3. The antibody-drug conjugate or pharmaceutically acceptable salt or solvate thereof according to embodiment 1 or 2, wherein the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises a heavy chain variable region and a light chain variable region, wherein:

[0346] (1) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 11 and 16, respectively;

[0347] (2) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 12 and 17, respectively;

[0348] (3) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 13 and 17, respectively;

[0349] (4) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 14 and 17, respectively;

[0350] (5) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 15 and 17, respectively;

[0351] (6) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 12 and 18, respectively;

[0352] (7) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 13 and 18, respectively;

[0353] (8) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 14 and 18, respectively;

[0354] (9) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 15 and 18, respectively;

[0355] (10) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 29 and 34, respectively;

[0356] (11) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 30 and 35, respectively;

[0357] (12) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 31 and 35, respectively;

[0358] (13) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 32 and 35, respectively;

[0359] (14) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 33 and 35, respectively;

[0360] (15) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 30 and 36, respectively;

[0361] (16) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 31 and 36, respectively;

[0362] (17) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 32 and 36, respectively;

[0363] (18) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 33 and 36, respectively;

[0364] (19) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 43 and 44, respectively;

[0365] (20) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 51 and 52, respectively; or

[0366] (21) The heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences shown in SEQ ID NOs: 59 and 60, respectively.

[0367] Embodiment 4. The antibody drug conjugate according to any one of Embodiments 1-3, or a pharmaceutically acceptable salt or solvate thereof, wherein the anti-CLDN18.2 antibody or antigen-binding fragment thereof is of IgG1, IgG2 or IgG4 isotype.

[0368] Embodiment 5. The antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof according to any one of Embodiments 1 to 4, wherein the anti-CLDN18.2 antibody further comprises a heavy chain constant region and a light chain constant region, wherein the heavy chain constant region comprises the amino acid sequence of SEQ ID NO: 1 or an amino acid sequence having 1, 2, 3, 4 or 5 amino acid substitutions, deletions or additions compared to the amino acid sequence of SEQ ID NO: 1, and the light chain constant region comprises the amino acid sequence of SEQ ID NO: 2 or an amino acid sequence having 1, 2, 3, 4 or 5 amino acid substitutions, deletions or additions compared to the amino acid sequence of SEQ ID NO: 2.

[0369] Embodiment 6. The antibody drug conjugate according to any one of Embodiments 1-5, or a pharmaceutically acceptable salt or solvate thereof, wherein the anti-CLDN18.2 antibody comprises a heavy chain and a light chain, wherein

[0370] (1) the heavy chain comprises an amino acid sequence that is at least 80% identical to the amino acid sequence of SEQ ID NO: 61, and the light chain comprises an amino acid sequence that is at least 80% identical to the amino acid sequence of SEQ ID NO: 62; or

[0371] (2) The heavy chain comprises an amino acid sequence that is at least 80% identical to the amino acid sequence shown in SEQ ID NO: 63, and the light chain comprises an amino acid sequence that is at least 80% identical to the amino acid sequence shown in SEQ ID NO: 64.

[0372] Embodiment 7. The antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof according to any one of embodiments 1-6, wherein U is a camptothecin-type topoisomerase I inhibitor, and L and / or U have a deuterated modification.

[0373] Embodiment 8. The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to Embodiment 7, wherein U is SN-38, an SN-38 derivative, exatecan, or an exatecan derivative, preferably an exatecan derivative.

[0374] Embodiment 9. The antibody-drug conjugate according to embodiment 8, or a pharmaceutically acceptable salt or solvate thereof, wherein -U is a structure represented by the following formula Ia:

[0375] Embodiment 10. The antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof according to any one of embodiments 7-9, wherein -L- is a structure represented by the following formula IIa:

[0376] wherein R1 and R2 are independently selected from hydrogen or deuterium;

[0377] Furthermore, the 3-position of -(succinimide-3-yl-N)- in the structure shown is connected to the Ab, and the methylene group at the other end is connected to the U.

[0378] Embodiment 11. The antibody drug conjugate according to embodiment 7, or a pharmaceutically acceptable salt or solvate thereof, wherein -LU is a structure represented by the following formula IIIa:

[0379] wherein R1 and R2 are independently selected from hydrogen or deuterium.

[0380] Embodiment 12. The antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof according to Embodiment 11, wherein -LU is a structure represented by the following formula IIIa-1, IIIa-2, IIIa-3 or IIIa-4:

[0381] Embodiment 13. The antibody-drug conjugate according to Embodiment 7 or a pharmaceutically acceptable salt or solvate thereof, wherein the structure of the antibody-drug conjugate is shown in Formula IV below:

[0382] wherein R1 and R2 are independently selected from hydrogen or deuterium.

[0383] Embodiment 14. The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to Embodiment 13, wherein the structure of the antibody-drug conjugate is represented by Formula IV-1, IV-2, IV-3 or IV-4:

[0384] Embodiment 15. The antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof according to any one of Embodiments 1 to 14, wherein n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7 or 7-8; preferably an integer selected from 2-8, 3-8, 4-8, 5-8, 6-8 or 7-8; more preferably an integer selected from 6-8.

[0385] Embodiment 16. The antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to any one of Embodiments 1 to 15, wherein the antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof exhibits one or a combination of the following properties:

[0386] (a) Binding to CLDN18.2;

[0387] (b) blocking the binding of CLDN18.2 to its ligand;

[0388] (c) Demonstrates endocytosis in cells expressing CLDN18.2;

[0389] (d) has cytotoxic activity against tumor cells expressing CLDN18.2;

[0390] (e) has a bystander effect;

[0391] (f) having ADCC activity;

[0392] (g) having CDC activity;

[0393] (h) does not bind to CLDN18.1;

[0394] (i) does not bind to cells that do not express CLDN18.2; and

[0395] (j) No ADCC and / or CDC activity against cells expressing CLDN18.1.

[0396] Embodiment 17. A pharmaceutical composition comprising the antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to any one of Embodiments 1-16; preferably, the antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof in the pharmaceutical composition is heterogeneous or homogeneous; optionally, the pharmaceutical composition further comprises a pharmaceutically acceptable carrier.

[0397] Embodiment 18. The pharmaceutical composition of embodiment 17, wherein the antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof in the pharmaceutical composition is heterogeneous and the DAR of the pharmaceutical composition is 0-10, 0-9, 0-8, 1-10, 1-9, 1-8, 2-10, 2-9, 2-8, 3-8, 4-8, 5-8, 6-8, 7-8, 7.2-8, 7.4-8, 7.5-8, 7.6-8, 7.7-8, 7.8-8, 7.8-7.9 or 7.9-8; preferably 7-8, 7.2-8, 7.4-8, 7.6-8, 7.7-8; more preferably about 7.1, about 7.2, about 7.4, about 7.6, about 7.7 or about 8.

[0398] Embodiment 19. Use of the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to any one of Embodiments 1-16, or the pharmaceutical composition according to Embodiment 17 or 18, in the preparation of a medicament for treating tumors.

[0399] Embodiment 20. Use of the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to any one of Embodiments 1-16, or the pharmaceutical composition according to Embodiment 17 or 18, and a second therapeutic agent in the preparation of a medicament for treating tumors.

[0400] Embodiment 21. The use according to embodiment 19 or 20, wherein the tumor is a CLDN18.2-positive tumor; preferably, the tumor is gastric cancer, esophageal cancer, gastrointestinal cancer, pancreatic cancer, liver cancer, lung cancer, bronchial cancer, mesothelioma, kidney cancer, ovarian cancer, breast cancer, bladder cancer, uterine cancer, endometrial cancer, prostate cancer, testicular cancer, anal cancer, vaginal cancer, bile duct cancer, gallbladder cancer, head and neck cancer, spinal tumor, otolaryngology tumor, thyroid cancer, mesothelioma, bone cancer, skin cancer, melanoma, adenocarcinoma, sarcoma, neuroblastoma, glioblastoma, brain cancer, central nervous system cancer, neuroendocrine tumor, leukemia, lymphoma and / or myeloma.

[0401] Embodiment 22. A method for treating tumors, comprising administering a therapeutically effective amount of the antibody-drug conjugate according to any one of Embodiments 1-16 or a pharmaceutically acceptable salt or solvate thereof, or the pharmaceutical composition according to Embodiment 17 or 18 to a patient in need thereof.

[0402] Embodiment 23. The method according to embodiment 22, comprising contacting tumor cells with the antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to any one of embodiments 1-16, or the pharmaceutical composition according to embodiment 17 or 18, thereby killing the tumor cells or inhibiting the growth of the tumor cells.

[0403] Embodiment 24. The method of embodiment 22 or 23, wherein the method further comprises administering a second therapeutic agent.

[0404] Embodiment 25. The method according to any one of Embodiments 22-24, wherein the tumor is a CLDN18.2-positive tumor; preferably, the tumor is gastric cancer, esophageal cancer, gastrointestinal cancer, pancreatic cancer, liver cancer, lung cancer, bronchial cancer, mesothelioma, kidney cancer, ovarian cancer, breast cancer, bladder cancer, uterine cancer, endometrial cancer, prostate cancer, testicular cancer, anal cancer, vaginal cancer, bile duct cancer, gallbladder cancer, head and neck cancer, spinal tumor, otolaryngology tumor, thyroid cancer, mesothelioma, bone cancer, skin cancer, melanoma, adenocarcinoma, sarcoma, neuroblastoma, glioblastoma, brain cancer, central nervous system cancer, neuroendocrine tumor, leukemia, lymphoma and / or myeloma.

[0405] Embodiment 26. A method for preparing the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to any one of Embodiments 11-16, comprising treating an anti-CLDN18.2 antibody or an antigen-binding fragment thereof under reducing conditions, and then reacting the anti-CLDN18.2 antibody or the antigen-binding fragment thereof with a linker-payload selected from the structure represented by Formula III, wherein the structure represented by Formula III is as follows:

[0406] Wherein, R1 and R2 are independently selected from hydrogen or deuterium.

[0407] Embodiment 27. The method of Embodiment 26, wherein R1 and R2 are hydrogen.

[0408] Embodiment 28. An antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein the antibody-drug conjugate is formed by linking the structure represented by the following formula IIIa to an antibody or an antigen-binding fragment thereof.

[0409] wherein R1 and R2 are independently selected from hydrogen or deuterium, and the 3-position of -(succinimide-3-yl-N)- in the structure represented by Formula IIIa is linked to the antibody or its antigen-binding fragment;

[0410] The antibody or antigen-binding fragment thereof is an anti-CLDN18.2 antibody or antigen-binding fragment thereof, which comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3, wherein:

[0411] (1) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 11, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 11, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 11, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 16, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 16, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 16;

[0412] (2) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 12, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 12, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 12, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 17, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 17, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 17;

[0413] (3) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 13, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 13, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 13, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 17, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 17, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 17;

[0414] (4) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 14, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 14, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 14, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 17, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 17, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 17;

[0415] (5) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 15, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 15, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 15, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 17, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 17, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 17;

[0416] (6) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 12, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 12, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 12, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 18, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 18, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 18;

[0417] (7) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 13, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 13, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 13, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 18, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 18, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 18;

[0418] (8) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 14, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 14, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 14, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 18, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 18, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 18;

[0419] (9) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 15, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 15, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 15, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 18, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 18, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 18;

[0420] (10) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 29, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 29, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 29, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 34, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 34, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 34;

[0421] (11) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 30, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 30, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 30, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 35, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 35, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 35;

[0422] (12) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 31, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 31, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 31, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 35, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 35, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 35;

[0423] (13) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 32, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 32, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 32, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 35, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 35, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 35;

[0424] (14) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 33, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 33, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 33, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 35, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 35, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 35;

[0425] (15) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 30, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 30, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 30, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 36, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 36, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 36;

[0426] (16) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 31, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 31, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 31, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 36, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 36, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 36;

[0427] (17) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 32, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 32, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 32, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 36, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 36, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 36;

[0428] (18) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 33, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 33, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 33, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 36, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 36, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 36;

[0429] (19) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 43, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 43, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 43, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 44, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 44, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 44;

[0430] (20) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 51, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 51, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 51, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 52, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 52, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 52; or

[0431] (21) HCDR1 comprises the amino acid sequence of HCDR1 in SEQ ID NO: 59, HCDR2 comprises the amino acid sequence of HCDR2 in SEQ ID NO: 59, HCDR3 comprises the amino acid sequence of HCDR3 in SEQ ID NO: 59, LCDR1 comprises the amino acid sequence of LCDR1 in SEQ ID NO: 60, LCDR2 comprises the amino acid sequence of LCDR2 in SEQ ID NO: 60, and LCDR3 comprises the amino acid sequence of LCDR3 in SEQ ID NO: 60.

[0432] Embodiment 29. The antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to embodiment 28, wherein:

[0433] (1) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 3, 4, 7, 8, 9, and 10, respectively;

[0434] (2) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 3, 5, 7, 8, 9, and 10, respectively;

[0435] (3) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 3, 6, 7, 8, 9, and 10, respectively;

[0436] (4) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 20, 24, 25, 26, and 27, respectively;

[0437] (5) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 21, 24, 25, 26, and 27, respectively;

[0438] (6) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 22, 24, 25, 26, and 27, respectively;

[0439] (7) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 23, 24, 25, 26, and 27, respectively;

[0440] (8) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 20, 24, 25, 26, and 28, respectively;

[0441] (9) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 21, 24, 25, 26, and 28, respectively;

[0442] (10) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 22, 24, 25, 26, and 28, respectively;

[0443] (11) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences of SEQ ID NOs: 19, 23, 24, 25, 26, and 28, respectively;

[0444] (12) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 37, 38, 39, 40, 41, and 42, respectively;

[0445] (13) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise the amino acid sequences of SEQ ID NOs: 45, 46, 47, 48, 49 and 50, respectively; or

[0446] (14) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise the amino acid sequences shown in SEQ ID NOs: 53, 54, 55, 56, 57 and 58, respectively.

[0447] Embodiment 30. The antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof according to embodiment 28 or 29, wherein the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises a heavy chain variable region and a light chain variable region, wherein:

[0448] (1) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 11 and 16, respectively;

[0449] (2) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 12 and 17, respectively;

[0450] (3) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 13 and 17, respectively;

[0451] (4) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 14 and 17, respectively;

[0452] (5) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 15 and 17, respectively;

[0453] (6) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 12 and 18, respectively;

[0454] (7) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 13 and 18, respectively;

[0455] (8) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 14 and 18, respectively;

[0456] (9) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 15 and 18, respectively;

[0457] (10) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 29 and 34, respectively;

[0458] (11) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 30 and 35, respectively;

[0459] (12) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 31 and 35, respectively;

[0460] (13) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 32 and 35, respectively;

[0461] (14) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 33 and 35, respectively;

[0462] (15) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 30 and 36, respectively;

[0463] (16) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 31 and 36, respectively;

[0464] (17) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 32 and 36, respectively;

[0465] (18) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 33 and 36, respectively;

[0466] (19) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 43 and 44, respectively;

[0467] (20) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 51 and 52, respectively; or

[0468] (21) The heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences shown in SEQ ID NOs: 59 and 60, respectively.

[0469] Embodiment 31. The antibody drug conjugate according to any one of Embodiments 28-30, or a pharmaceutically acceptable salt or solvate thereof, wherein the anti-CLDN18.2 antibody or antigen-binding fragment thereof is of IgG1, IgG2 or IgG4 isotype.

[0470] Embodiment 32. The antibody drug conjugate according to any one of Embodiments 28 to 31, or a pharmaceutically acceptable salt or solvate thereof, wherein the anti-CLDN18.2 antibody further comprises a heavy chain constant region and a light chain constant region, wherein the heavy chain constant region comprises the amino acid sequence of SEQ ID NO: 1 or an amino acid sequence having 1, 2, 3, 4 or 5 amino acid substitutions, deletions or additions compared to the amino acid sequence of SEQ ID NO: 1, and the light chain constant region comprises the amino acid sequence of SEQ ID NO: 2 or an amino acid sequence having 1, 2, 3, 4 or 5 amino acid substitutions, deletions or additions compared to the amino acid sequence of SEQ ID NO: 2.

[0471] Embodiment 33. The antibody drug conjugate according to any one of Embodiments 28-32, or a pharmaceutically acceptable salt or solvate thereof, wherein the anti-CLDN18.2 antibody comprises a heavy chain and a light chain, wherein

[0472] (1) the heavy chain comprises an amino acid sequence that is at least 80% identical to the amino acid sequence of SEQ ID NO: 61, and the light chain comprises an amino acid sequence that is at least 80% identical to the amino acid sequence of SEQ ID NO: 62; or

[0473] (2) The heavy chain comprises an amino acid sequence that is at least 80% identical to the amino acid sequence shown in SEQ ID NO: 63, and the light chain comprises an amino acid sequence that is at least 80% identical to the amino acid sequence shown in SEQ ID NO: 64.

[0474] Embodiment 34. The antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof according to any one of Embodiments 28-33, wherein R1 and R2 are both hydrogen.

[0475] Embodiment 35. The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to any one of Embodiments 28-34, wherein the antibody-drug conjugate is formed by linking the structure represented by Formula IIIa to the antibody or antigen-binding fragment thereof via a thioether bond.

[0476] Embodiment 36. The antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof according to any one of embodiments 28 to 35, wherein the antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof exhibits one or a combination of the following properties:

[0477] (a) Binding to CLDN18.2;

[0478] (b) blocking the binding of CLDN18.2 to its ligand;

[0479] (c) Demonstrates endocytosis in cells expressing CLDN18.2;

[0480] (d) has cytotoxic activity against tumor cells expressing CLDN18.2;

[0481] (e) has a bystander effect;

[0482] (f) having ADCC activity;

[0483] (g) having CDC activity;

[0484] (h) does not bind to CLDN18.1;

[0485] (i) does not bind to cells that do not express CLDN18.2; and

[0486] (j) No ADCC and / or CDC activity against cells expressing CLDN18.1.

[0487] Embodiment 37. A pharmaceutical composition comprising the antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to any one of Embodiments 28-36; preferably, the antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof in the pharmaceutical composition is heterogeneous or homogeneous; optionally, the pharmaceutical composition further comprises a pharmaceutically acceptable carrier.

[0488] Embodiment 38. The pharmaceutical composition of embodiment 37, wherein the antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof in the pharmaceutical composition is heterogeneous and the DAR of the pharmaceutical composition is 0-10, 0-9, 0-8, 1-10, 1-9, 1-8, 2-10, 2-9, 2-8, 3-8, 4-8, 5-8, 6-8, 7-8, 7.2-8, 7.4-8, 7.5-8, 7.6-8, 7.7-8, 7.8-8, 7.8-7.9 or 7.9-8; preferably 7-8, 7.2-8, 7.4-8, 7.6-8, 7.7-8; more preferably about 7.1, about 7.2, about 7.4, about 7.6, about 7.7 or about 8.

[0489] Embodiment 39. Use of the antibody-drug conjugate or pharmaceutically acceptable salt or solvate of any one of Embodiments 28-36, or the pharmaceutical composition of Embodiment 37 or 38, in the preparation of a medicament for treating tumors.

[0490] Embodiment 40. Use of the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to any one of Embodiments 28-36, or the pharmaceutical composition according to Embodiment 37 or 38, and a second therapeutic agent in the preparation of a medicament for treating tumors.

[0491] Embodiment 41. The use according to embodiment 39 or 40, wherein the tumor is a CLDN18.2-positive tumor; preferably, the tumor is gastric cancer, esophageal cancer, gastrointestinal cancer, pancreatic cancer, liver cancer, lung cancer, bronchial cancer, mesothelioma, kidney cancer, ovarian cancer, breast cancer, bladder cancer, uterine cancer, endometrial cancer, prostate cancer, testicular cancer, anal cancer, vaginal cancer, bile duct cancer, gallbladder cancer, head and neck cancer, spinal tumor, otolaryngology tumor, thyroid cancer, mesothelioma, bone cancer, skin cancer, melanoma, adenocarcinoma, sarcoma, neuroblastoma, glioblastoma, brain cancer, central nervous system cancer, neuroendocrine tumor, leukemia, lymphoma and / or myeloma.

[0492] Embodiment 42. A method for treating tumors, comprising administering to a patient in need thereof a therapeutically effective amount of the antibody-drug conjugate of any one of Embodiments 28-36 or a pharmaceutically acceptable salt or solvate thereof, or the pharmaceutical composition of Embodiment 37 or 38.

[0493] Embodiment 43. The method according to embodiment 42, comprising contacting tumor cells with the antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to any one of embodiments 28-36, or the pharmaceutical composition according to embodiment 37 or 38, thereby killing the tumor cells or inhibiting the growth of the tumor cells.

[0494] Embodiment 44. The method of embodiment 42 or 43, wherein the method further comprises administering a second therapeutic agent.

[0495] Embodiment 45. The method according to any one of Embodiments 42-44, wherein the tumor is a CLDN18.2-positive tumor; preferably, the tumor is gastric cancer, esophageal cancer, gastrointestinal cancer, pancreatic cancer, liver cancer, lung cancer, bronchial cancer, mesothelioma, kidney cancer, ovarian cancer, breast cancer, bladder cancer, uterine cancer, endometrial cancer, prostate cancer, testicular cancer, anal cancer, vaginal cancer, bile duct cancer, gallbladder cancer, head and neck cancer, spinal tumor, otolaryngology tumor, thyroid cancer, mesothelioma, bone cancer, skin cancer, melanoma, adenocarcinoma, sarcoma, neuroblastoma, glioblastoma, brain cancer, central nervous system cancer, neuroendocrine tumor, leukemia, lymphoma and / or myeloma.

[0496] Example

[0497] For the sake of clarity, the present disclosure is further illustrated with examples, but the examples do not limit the scope of the present disclosure. The reagents used in the present disclosure are generally commercially available and can be used without further purification.

[0498] The cells and their sources involved in the embodiments of the present disclosure are shown in the following table:

[0499] Example 1 Production of anti-CLDN18.2 monoclonal antibodies

[0500] Construction of stable cell lines

[0501] The cDNA encoding human CLDN18.2 (SEQ ID NO: 65) was synthesized and then subcloned into the expression vector pcDNA3.1. Following the instructions for Lipofectamine 2000 transfection reagent (Thermo, catalog number 11668019), the expression vector was transfected into U2OS and NIH-3T3 cells, respectively, to generate the stable cell lines U2OS-CLDN18.2 and NIH-3T3-CLDN18.2.

[0502] Mouse immunization

[0503] Balb / c mice were immunized with NIH-3T3-CLDN18.2 cells as immunogen, and 5×10 6 -10×10 6 NIH-3T3-CLDN18.2 cells were immunized once every 2 weeks for 5 times. 3 days before fusion, 1×10 7 NIH-3T3-CLDN18.2 cells were used for sprint immunization. After immunization, serum was collected from each mouse to measure anti-CLDN18.2-specific antibody titers. Mice with higher antibody titers were selected for subsequent spleen cell fusion.

[0504] Cell fusion

[0505] The splenocytes (1×10 8 ) and SP2 / 0 myeloma cells (5×10 7 After fusion, the cells were resuspended in HAT complete medium and dispensed into a 96-well plate at 0.2 mL / well. The plates were cultured at 37°C in a 5% CO2 incubator. After 7-10 days, the hybridoma cell culture supernatant was collected for testing.

[0506] Hybridoma screening

[0507] Antibody binding activity to CLDN18.2 was assessed by ELISA. U2OS-CLDN18.2 cells were plated at 10,000 cells / well in a 96-well plate and cultured overnight in a 37°C, 5% CO2 incubator. The cell culture supernatant was discarded, and the 96-well plate was washed three times with PBS buffer. The plate was fixed with 2% paraformaldehyde for 30 minutes at room temperature. The plate was washed three times with PBS buffer, and 100 μL of hybridoma cell culture supernatant was added to each well and incubated at room temperature for 1 hour. The plate was washed three times with PBS buffer, and 100 μL of HRP-Goat Anti-Mouse IgG Fcγ (Jackson ImmunoResearch, catalog number 115-035-071) was added to each well and incubated at room temperature for 1 hour. The 96-well plate was washed three times with PBS buffer, and 100 μL of TMB (Thermo, catalog number 00-4201-56) was added to each well and incubated for 10 minutes. Then, 50 μL of stop solution (1 M H2SO4) was added to each well to stop the reaction. The OD value was read at a wavelength of 450 nm using a microplate reader (Thermo, Varioskan Flash).

[0508] Hybridoma cells that tested positive by ELISA were selected, and the binding activity of the antibodies in the culture supernatant of the hybridoma cells to the cell lines KATOIII and NUGC-4 that naturally expressed CLDN18.2 was detected by FACS.

[0509] cDNA acquisition

[0510] Hybridoma cells that tested positive by ELISA and FACS were selected, and total RNA was isolated from the cells using a total RNA extraction kit (Takara, catalog number 9767). First-strand cDNA was synthesized using Superscript III reverse transcriptase according to the kit instructions (Thermo, catalog number 18080051). Using the first-strand cDNA as a template, the heavy and light chain variable regions of the antibody were amplified by PCR using mouse IgG primers and kappa primers. The PCR mixture was electrophoretically separated on a 1% agarose / Tris-borate gel containing 0.5 μg / mL ethidium bromide. DNA fragments of the expected size were excised from the gel and purified. The purified PCR product was cloned into the pMD-19T vector (Takara, catalog number 6013) and transformed into DH5α competent Escherichia coli cells (Takara, catalog number 9057) for culture. Single colonies were picked from LB solid culture plates for DNA sequencing. The heavy chain variable region sequences and light chain variable region sequences of antibodies (murine antibodies 28G3, 40F6, 22F12, 34G6 and 10D8) were obtained.

[0511] Construction and expression of humanized antibodies

[0512] Murine antibodies 28G3 (heavy chain variable region sequence SEQ ID NO: 11, light chain variable region sequence SEQ ID NO: 16) and 40F6 (heavy chain variable region sequence SEQ ID NO: 29, light chain variable region sequence SEQ ID NO: 34) were selected for humanization design.

[0513] The murine antibodies 28G3 and 40F6 were humanized using the CDR-graft method combined with computer-aided design. The heavy and light chain variable region sequences of the murine antibodies were compared against protein databases to identify human germline antibody sequences with the highest sequence homology. The CDRs of the murine antibodies 28G3 and 40F6 were grafted onto the frameworks of the selected human germline antibody sequences, and further amino acid residues in the CDRs and / or frameworks were mutated to obtain a larger number of candidate variable region sequences.

[0514] The humanized VL region gene fragment was linked to the human kappa chain constant region (amino acid sequence as shown in SEQ ID NO: 2) to construct a humanized light chain, and the humanized VH region gene fragment was linked to the human IgG1 constant region (amino acid sequence as shown in SEQ ID NO: 1) to construct a humanized heavy chain. The humanized heavy chain expression plasmid and the humanized light chain expression plasmid were co-transfected into CHO cells for protein expression. The transfected cells were cultured at 37°C in the presence of 8% CO2. After 7-10 days of culture, the cell culture supernatant was obtained by centrifugation, and the humanized antibody in the cell culture supernatant was purified using a Protein A column (GE healthcare).

[0515] The amino acid sequence of the heavy chain of the humanized antibody hz28G3-1.1 is shown in SEQ ID NO: 61, and the amino acid sequence of the light chain is shown in SEQ ID NO: 62; the amino acid sequence of the heavy chain of the humanized antibody hz28G3-1.3 is shown in SEQ ID NO: 63, and the amino acid sequence of the light chain is shown in SEQ ID NO: 64. The variable region amino acid sequences of other humanized antibodies are shown in Table S1.

[0516] Example 2 Preparation of MC-GGFG-deuterated DXd (MC-GGFG-DDDXd)

[0517] Step 1 Synthesis of Intermediate A

[0518] Under nitrogen, 80 g of ethyl diazoacetate was added to a 3 L single-necked flask. 800 mL of dichloromethane and 800 mL of a 1% deuterated acetic acid solution (8 g of deuterated acetic acid dissolved in 800 mL of deuterated water) were then added. The single-necked flask was placed in a darkened state and stirred at room temperature for 75 hours. The organic phase was separated and collected, and the aqueous phase was extracted twice with dichloromethane (200 mL x 2). The organic phases were combined. The organic phase was washed with 200 mL of deuterated water, dried over anhydrous sodium sulfate, filtered to remove the sodium sulfate, and the filtrate was concentrated to dryness under reduced pressure at 20°C to obtain 49.25 g of intermediate A, with a yield of 66%. The CAS number of intermediate A is 1356471-71-0.

[0519] Step 2 Synthesis of Intermediate B

[0520] Weigh 50g of N-Fmoc-glycyl-glycine into a 2L round-bottom flask, add 750mL of tetrahydrofuran and 150mL of glacial acetic acid, stir at 40°C for 20 minutes, add 100g of lead tetraacetate, raise the temperature to 80°C, and continue reacting for 3 hours. Cool to room temperature, filter with suction, and wash the filter cake with 250mL of ethyl acetate. Concentrate the filtrate to dryness, add 330mL of dichloromethane and 670mL of ethyl acetate to dissolve the resulting organic phase. Wash the organic phase three times with 30% potassium bicarbonate aqueous solution (500mL x 3), dry over anhydrous sodium sulfate, and filter. Concentrate the filtrate to dryness under reduced pressure, dissolve the solution in 100mL of dichloromethane, then add 100mL of n-hexane. Stir at room temperature until a solid precipitates, then add 300mL of a mixture of n-hexane and dichloromethane (n-hexane:dichloromethane = 1:1) and stir overnight. The filter cake was filtered and dried in a vacuum oven at 40°C for 4 hours to obtain 37.3 g of intermediate B with a yield of 72%. LC-MS (ESI) m / z: 391.09 [M+Na] + ; CAS number of intermediate B: 1599440-06-8.

[0521] Step 3 Synthesis of Intermediate C

[0522] Weigh 78g of intermediate B into a 3000mL single-necked flask, add 800mL of dichloromethane and 45g of intermediate A, and place the 3000mL single-necked flask in an ice-water bath to cool to 0°C. Dissolve 16g of lithium tert-butoxide in 400mL of dichloromethane to prepare a lithium tert-butoxide solution. Add the lithium tert-butoxide solution to the 3000mL single-necked flask and react at 0°C for 3 hours. Bring to room temperature, add 800mL of water and stir. Separate the liquid, collect the organic phase, extract the aqueous phase with 400mL of dichloromethane, and combine the organic phases. The organic phase is washed once with 800mL of saturated brine, dried over anhydrous sodium sulfate, filtered, and the filtrate is concentrated under reduced pressure. Chromatography is performed on a silica gel column (petroleum ether: ethyl acetate = 3:1) to obtain 61g of intermediate C with a yield of 70%. LC-MS (ESI) m / z: 437.34 [M+Na] + ; CAS number of intermediate C: 2760715-83-9.

[0523] Step 4 Synthesis of Compound D

[0524] 31.2 g of Intermediate C was added to 270 mL of deuterated methanol and 70 mL of heavy water, stirred under ice, and then 5.5 g of NaOH was added. The mixture was brought to room temperature and stirred overnight. 300 mL of ethyl acetate and 300 mL of water were added to the reaction solution for extraction. 20 mL of glacial acetic acid was added to the aqueous layer to adjust the pH to 2-3. A solid precipitated and was filtered to obtain 20.3 g of Compound D, with a yield of 69.8%. 1 H-NMR (500MHz, DMSO-d6) δ8.70(1H,t,J=6.6),7.89(2H,d,J=7.5),7.72(2H,d,J=7.5),7.57(1H,t,J=6.0),7.42(2H,t,J=7.5) ,7.34(2H,t,J=7.5),4.61(2H,d,J=6.6),4.30(2H,d,J=7.1),4.23(1H,m),3.64(2H,d,J=6.0); LC-MS(ESI)m / z:409.08[M+Na] + .

[0525] Step 5 Synthesis of Compound E

[0526] Weigh 2.0g of exatecan mesylate dihydrate and 1.63g of compound D and add them to a 100mL round-bottom flask. Add 40mL of N,N-dimethylformamide and stir. Cool to 0°C. Add 2.0g of 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate and 1.82g of N,N-diisopropylethylamine in sequence and react at 0°C for 3h. Pour the reaction solution into 120mL of ice water and stir for 1h. Filter and dissolve the filter cake with dichloromethane. Chromatography was performed on a silica gel column (100g of 100-200 mesh silica gel, dichloromethane: methanol = 30:1, 2L) to obtain 2.6g of compound E. The yield was 92%, 1 H-NMR (500MHz, DMSO-d6), δ8.78(1H,t,J=6.6),8.47(1H,d,J=9.0),7.86(2H,d,J=7.5),7.73(1H,d,J=11 .0),7.68(2H,d,J=7.5),7.53(1H,t,J=6.0),7.39(2H,t,J=7.5),7.30(2H,m),7.29(1H,s),6.50(1H,brs ),5.56(1H,m),5.39(2H,m),5.14(2H,m),4.64(2H,m),4.25(2H,d,J=6.8),4.19(1H,m),3.62(2H,d,J=6. 0),3.15(2H,m),2.35(3H,s),2.17(2H,m),1.83(2H,m),0.85(3H,t,J=7.3); LC-MS(ESI)m / z:804.84[M+H] + .

[0527] Step 6 Preparation of Compound F

[0528] Weigh 0.38g of 1,8-diazabicyclo[5.4.0]undec-7-ene into a 100mL round-bottom flask, then add 20mL of tetrahydrofuran to the round-bottom flask and stir. Cool to 0°C. Weigh 2.0g of compound E and prepare a solution with 20mL of tetrahydrofuran. Slowly add the prepared solution of compound E to the 100mL round-bottom flask, naturally warm to room temperature, and react for 3h. Filter under nitrogen protection to obtain 1.45g of compound F. Yield 98%, 1H-NMR(500MHz, DMSO-d6)δ8.76(1H,m),7.72(1H,m),7.28(1H,s),5.48(3H,m),5.16(2H,m),4.61(2H,m),3.40 (2H,m),3.20(2H,m),2.35(3H,s),2.17(2H,m),1.83(2H,m),0.86(3H,t,J=7.1); LC-MS(ESI)m / z:582.39[M+H] + .

[0529] Step 7 Preparation of Compound H

[0530] Weigh 1.00g of compound F and 0.97g of compound G into a 100mL round-bottom flask, and add 10mL of N,N-dimethylformamide. Cool to -20°C, add 0.34g of 1-hydroxybenzotriazole and 0.49g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and react at -20°C for 3h. Add 20mL of dichloromethane and 20mL of water to the reaction solution, stir for 0.5h, let it stand, separate the liquids, and collect the organic phase. The organic phase is dried over anhydrous sodium sulfate and filtered. The filtrate is concentrated to dryness under reduced pressure. Silica gel column chromatography (dichloromethane: methanol = 15:1) is used to obtain 400mg of compound H, with a yield of approximately 22%, MS m / z: 1037.08 [M+H] + . 1H-NMR (500MHz, DMSO-d6) δ8.62(1H,t,J=6.5),8.49(1H,d,J=8.5),8.29(1H,t,J=5.5),8.12(1H,d,J=8.0),8.06(1H,t,J=5.5),8.00(1H,t,J=5 .5),7.74(1H,d,J=10.5),7.30(1H,s),7.27~7.12(5H,m),6.98(2H,s), 6.51(1H,brs),5.61~5.58(1H,m),5.45~5.37(2H,m),5.22~5.13(2H,m), 4.64(2H,d,J=6.5),4.49~4.45(1H,m),3.76~3.57(6H,m),3.37~3.32(2 H,m),3.24~3.09(2H,m),3.02(1H,dd,J=4.5,14.0),2.77(1H,dd,J=9.5 ,13.5),2.36(3H,s),2.23~2.14(2H,m),2.09(2H,t,J=7.5),1.91~1.79 (2H,m),1.49~1.42(4H,m),1.20~1.14(2H,m),0.87(3H,t,J=7.5); HR-MS m / z:1036.4194[M+H] + .

[0531] Example 3 Preparation of anti-CLDN18.2 antibody drug conjugate

[0532] Reagents:

[0533] Antibodies: anti-CLDN18.2 antibodies hz28G3-1.1 and hz28G3-1.3, 15F9 prepared in Example 1 (prepared in-house, heavy and light chain amino acid sequences are shown in SEQ ID NOs: 67 and 68 of the present disclosure);

[0534] Linker-payload: Compound H (MC-GGFG-DDDXd) prepared in Example 2.

[0535] Experimental process:

[0536] 1. Antibody Reduction: The antibody was replaced in histidine buffer (L-histidine 1.43 mg / mL, L-histidine hydrochloride monohydrate 2.27 mg / mL) at pH 6.0, and the antibody concentration was adjusted to 10 mg / mL with histidine buffer (pH 6.0). This solution was placed in a light-proof glass bottle, and 10 mM TCEP (tris(2-carboxyethyl)phosphine hydrochloride) solution was added thereto to adjust the molar ratio of antibody to TCEP to 1:8. The mixture was incubated in the dark at 35°C for 1 hour with gentle stirring to reduce the interchain disulfide bonds of the antibody to obtain reaction solution 1.

[0537] 2. Coupling of the Antibody and Linker-Payload: After incubating reaction solution 1 at 22°C for 10 minutes, DMSO solution was added (DMSO solution: reaction solution 1 (v / v) = 1:20) and mixed. A 10 mg / mL linker-payload solution dissolved in DMSO was added to adjust the molar ratio of the antibody to the linker-payload to 1:10. The mixture was incubated in the dark at 22°C for 2 hours with gentle stirring to connect the antibody and linker-payload to obtain reaction solution 2.

[0538] 3. Coupling termination and purification: The reaction solution 2 was ultrafiltered using a pH 6.0 histidine buffer to obtain anti-CLDN18.2 antibody-drug conjugates hz28G3-1.1-DDDXd, hz28G3-1.3-DDDXd, and 15F9-DDDXd.

[0539] Example 4 Determination of DAR Value of Antibody Drug Conjugates

[0540] DAR values ​​were determined using LC-MS. An appropriate amount of the anti-CLDN18.2 antibody-drug conjugate prepared in Example 3 was added to an appropriate amount of glycosidase PNGase F (Ruian Biotechnology, China) and reacted at 37°C overnight. Mass spectrometry analysis was performed using a high-resolution mass spectrometer Xevo G2-XS (Waters, USA), acquiring data in native, positive ion mode. Data processing was performed using UNIFI 1.8.2.169 (Waters, USA).

[0541] The anti-CLDN18.2 antibody-drug conjugate prepared by the method of Example 3 comprises:

[0542] hz28G3-1.1-DDDXd, whose measured DAR value is 7.2;

[0543] hz28G3-1.3-DDDXd, whose measured DAR value is 7.4;

[0544] 15F9-DDDXd, the measured DAR value is 7.7.

[0545] Example 5 Preparation of anti-CLDN18.2 antibody drug conjugates and determination of DAR values

[0546] The following anti-CLDN18.2 antibody drug conjugate was prepared by referring to the method in Example 3 and the DAR value was determined by referring to the method in Example 4:

[0547] hz28G3-1.1-DDDXd, whose measured DAR value is 7.4;

[0548] hz28G3-1.3-DDDXd, its measured DAR value is 7.6.

[0549] Example 6 Aggregation Verification of Antibody Drug Conjugates

[0550] The components of the anti-CLDN18.2 antibody drug conjugate prepared in Example 3 were separated using a gel chromatography column. A neutral pH buffer solution supplemented with 10% isopropanol was used as the mobile phase for elution, and the components were eluted in descending order of molecular weight. The column was an ACQUITY UPLC Protein BEH SEC Column. A 1.7 μm, 4.6 × 300 mm gel chromatography column was used at 25°C. The mobile phase consisted of 50 mM phosphate buffer-200 mM sodium chloride-10% isopropanol, pH 7.0 (12.53 g of disodium hydrogen phosphate dodecahydrate, 2.33 g of sodium dihydrogen phosphate dihydrate, and 11.69 g of sodium chloride were weighed, added to approximately 800 mL of ultrapure water, and stirred until fully dissolved. 100 mL of isopropanol was added, and the volume was brought to 1000 mL with ultrapure water. Mix thoroughly, and filter through a 0.22 μm filter. A precise amount of 20 μg of the anti-CLDN18.2 antibody conjugate was injected into the liquid chromatograph and detected at a wavelength of 280 nm. The flow rate was 0.3 mL / min, and isocratic elution was performed for 15 min.

[0551] Data processing and quantitative analysis of the results were performed using the area normalization method. The peak area percentages of aggregates, monomers, and low-molecular-weight impurities in the anti-CLDN18.2 antibody-drug conjugate were calculated. Aggregates are present before the main peak, monomers are present during the main peak, and low-molecular-weight impurities are present after the main peak. The percentages of monomers, aggregates, and low-molecular-weight impurities in the anti-CLDN18.2 antibody-drug conjugate are shown in Table 1.

[0552] Table 1 Monomer, aggregate and low molecular weight impurity contents of anti-CLDN18.2 antibody drug conjugates

[0553] Example 7 Cell Binding Activity of Anti-CLDN18.2 Antibody Drug Conjugates

[0554] The cell binding activity of the anti-CLDN18.2 antibody drug conjugate prepared in Example 5 was detected by flow cytometry using hz28G3-1.1 and hz28G3-1.3 as controls. NIH-3T3, BxPC-3, and NCI-N87 cell lines overexpressing CLDN18.2 were diluted to 1×10 6 100 μL / well of the 96-well plate was added, and anti-CLDN 18.2 antibody drug conjugate was serially diluted in FACS buffer (Miltenyi Biotec, catalog number 130-091-221) (for BxPC-3 cells, the final concentration in the well was 300 nM as the starting concentration of the serial dilution, and the serial dilution was 4-fold, for a total of 10 concentrations; for NIH-3T3 and BxPC-3 cells, the final concentration in the well was 333.33 nM as the starting concentration of the serial dilution, and the serial dilution was 4-fold, for a total of 10 concentrations). After incubation at 4°C for 60 minutes, the plate was centrifuged at 1000 rpm for 5 minutes, the supernatant was discarded, and the plate was washed three times with pre-chilled PBS (pH 7.4). Goat-anti-human IgG Fcγ-PE secondary antibody (Jackson Biosciences, Inc., IL-64444) was added at a dilution of 1:200 (v / v). Immunoresearch, catalog number 109-116-170), 100 μL / well, incubated at 4°C for 30 minutes. Washed three times with pre-chilled PBS (pH 7.4), resuspended with 100 μL PBS (pH 7.4), and then analyzed using a flow cytometer (Sartorius, iQUE) to detect the fluorescence signal. The binding activity of the anti-CLDN18.2 antibody drug conjugate to cell surface CLDN18.2 was expressed by the mean fluorescence intensity (MFI) of the staining. Data analysis was performed using GraphPad Prism 5, and the results are shown in Figures 1A-1C. The calculated EC 50 The results are shown in Table 2. The results showed that both hz28G3-1.1-DDDXd and hz28G3-1.3-DDDXd could effectively bind to cells overexpressing CLDN18.2.

[0555] Table 2 Binding activity of antibodies or antibody drug conjugates to CLDN18.2 overexpressing cells

[0556] Example 8 Endocytosis experiment of anti-CLDN18.2 antibody drug conjugate

[0557] Flow cytometry was used to detect the endocytosis of the anti-CLDN18.2 antibody drug conjugate prepared in Example 5 in cells overexpressing CLDN18.2, using hz28G3-1.1 and hz28G3-1.3 as controls. The cell concentration of CLDN18.2-overexpressing NIH-3T3, BxPC-3, and NCI-N87 cell lines and the CLDN18.2-positive natural cell line NUGC-4 was adjusted to 2×10 6 The cells were incubated at 37°C for 15 minutes with a labeled antibody (Sartorius, 90564) and a serially diluted anti-CLDN18.2 antibody-drug conjugate (ADC) in FACS buffer (Miltenyi Biotec, catalog number 130-091-221) (volume ratio of labeled antibody to ADC was 1:1). The cells were then added to a 96-well plate at 20 μL / well. The anti-CLDN18.2 antibody-drug conjugate was diluted to a final concentration of 20 nM in the wells, and the cells were diluted 3-fold for a total of 8 concentrations. After incubation for 2 hours, the cells were placed on a flow cytometer (Sartorius, iQUE) and the fluorescence readings of the RL1 channel were measured. Data analysis was performed using GraphPad Prism 5, and the results are shown in Figures 2A-2D. The calculated EC values ​​were 0. 50 The results are shown in Table 3. The results indicate that hz28G3-1.1-DDDXd and hz28G3-1.3-DDDXd can effectively perform endocytosis in cells overexpressing CLDN18.2.

[0558] Table 3 Endocytosis of antibodies or antibody drug conjugates in CLDN18.2 overexpressing cells

[0559] Example 9: Killing of Tumor Cells by Anti-CLDN18.2 Antibody-Drug Conjugates

[0560] To detect the killing effect of the anti-CLDN18.2 antibody-drug conjugate prepared in Example 5 on CLDN18.2-positive tumor cells, the killing activity was tested using CLDN18.2-overexpressing NIH-3T3, BxPC-3, and NCI-N87 cells.

[0561] Cells in the logarithmic growth phase were taken and the cell density of NIH-3T3, BxPC-3 and NCI-N87 cells was adjusted to 1×10 4 / mL, 2×10 4 / mL and 2×10 4 / mL, 100 μL / well was added to a 96-well plate and cultured overnight at 37°C, 5% CO2. The anti-CLDN18.2 antibody-drug conjugate was prepared in DMEM medium supplemented with 10% FBS. For NIH-3T3 cells, a starting concentration of 3 μg / mL was used, and a three-fold serial dilution was performed for a total of 9 concentrations. For BxPC-3 and NCI-N87 cells, a starting concentration of 5 μg / mL was used, and a five-fold serial dilution was performed for a total of 9 concentrations. Remove the cells that have been cultured overnight, and add 50 μL / well of the diluted anti-CLDN18.2 antibody-drug conjugate to the experimental group, and 50 μL / well of DMEM medium containing 10% FBS to the control group. After continued culture for 96 h or 120 h, detect using the CellTiter-Glo Luminescent Cell Kit (Promega, Catalog No.: G7572). Specifically, remove the 96-well plate, add 75 μL of CTG detection solution (Promega, Catalog No.: G7572) to each well, shake to mix, incubate at room temperature in the dark for 10 min, then transfer 180 μL from each well to an opaque white plate, remove bubbles, read the chemiluminescence value, and calculate the cell survival rate.

[0562] Data analysis was performed using Graphpad Prism 5, and the results are shown in Figures 3A-3C. The calculated IC 50 The results are shown in Table 4. The results showed that hz28G3-1.1-DDDXd and hz28G3-1.3-DDDXd could effectively kill tumor cells overexpressing CLDN18.2.

[0563] Table 4 Cytotoxicity of anti-CLDN18.2 antibody-drug conjugates against CLDN18.2-positive tumor cells

[0564] Example 10 CDC activity of anti-CLDN18.2 antibody drug conjugate

[0565] NIH-3T3 cells were selected as target cells, and human complement (Quidel Corporation, catalog number A112) was used to detect the CDC activity of the anti-CLDN18.2 antibody drug conjugate prepared in Example 5.

[0566] The cell density of target NIH-3T3 cells was adjusted to 8 × 10 cells / mL using basal cell culture medium containing 0.1% BSA. 5100 nM, seed 50 μL / well in a 96-well plate. Serially dilute the anti-CLDN18.2 antibody-drug conjugate at 50 μL / well, starting at a final concentration of 100 nM. 4-fold serial dilutions are performed for a total of 8 concentrations. Human complement is diluted in basal cell culture medium containing 0.1% BSA and added to the 96-well plate at 50 μL / well to a final concentration of 10%. Centrifuge at 200 g for 1 minute, then incubate the 96-well plate at 37°C on a plate shaker for 30 minutes to allow for thorough mixing and contact between the complement and target cells. Finally, incubate in a 37°C, 5% CO2 incubator for 2 hours. After incubation, 110 μL of CellTiter-Glo Luminescent Cell Viability Assay (Promega, G7570) was added to each well and incubated at room temperature in the dark for 10 ± 5 min. The fluorescence value was measured using a microplate reader (Thermo) and the killing rate was calculated. Data analysis was performed using GraphPad Prism 5. The results are shown in Figure 4. The calculated IC 50 The results are shown in Table 5. The results showed that hz28G3-1.1-DDDXd and hz28G3-1.3-DDDXd could induce strong CDC effects on CLDN18.2-positive tumor cells.

[0567] Table 5 CDC activity of anti-CLDN18.2 antibody drug conjugates on NIH-3T3 cells

[0568] Example 11 Non-specific killing of anti-CLDN18.2 antibody drug conjugates

[0569] The nonspecific killing effect of the anti-CLDN18.2 antibody-drug conjugate prepared in Example 5 on CLDN18.2-negative cells was detected, and the killing activity was detected using NIH-3T3 cells overexpressing CLDN18.1.

[0570] The cDNA encoding human CLDN18.1 (SEQ ID NO: 66) was synthesized and then subcloned into the expression vector pcDNA3.1. Following the instructions for Lipofectamine 2000 transfection reagent (Thermo, catalog number 11668019), the expression vector was transfected into NIH-3T3 cells to generate NIH-3T3-CLDN18.1, which overexpresses CLDN18.1.

[0571] NIH-3T3-CLDN18.1 cells in the logarithmic growth phase were taken and the cell density was adjusted to 1×10 4100 μL / well of the 96-well plate was added and cultured overnight in a 37°C, 5% CO2 incubator. The anti-CLDN18.2 antibody-drug conjugate was prepared in DMEM medium containing 10% FBS. The cells that had been cultured overnight were removed, and 50 μL / well of the diluted anti-CLDN18.2 antibody-drug conjugate was added to the experimental group. The final concentration in the well was 20 nM, which was used as the starting concentration for the serial dilution, and a 3-fold serial dilution was performed for a total of 9 concentrations. The control group was added with 50 μL / well of DMEM medium containing 10% FBS. After further culture for 96 h, the cells were detected using the CellTiter-Glo Luminescent Cell Kit (Promega, Catalog No.: G7572). Specifically, the 96-well plate was removed, 75 μL of CTG detection solution (Promega, Catalog No.: G7572) was added to each well, and the mixture was mixed by vortexing. After incubation at room temperature in the dark for 10 min, 180 μL of each well was transferred to an opaque white plate, bubbles were removed, the chemiluminescence value was read, and the cell survival rate was calculated.

[0572] Data analysis was performed using Graphpad Prism 5, and the results are shown in Figure 5. The results showed that hz28G3-1.1-DDDXd and hz28G3-1.3-DDDXd had no killing activity against NIH-3T3-CLDN18.1 cells.

[0573] Example 12 Bystander Effect of Anti-CLDN18.2 Antibody Drug Conjugate

[0574] BxPC-3 cells overexpressing CLDN18.2 were selected as positive cells, and U2OS cells stably expressing luciferase (U2OS-Luciferase) were selected as negative cells, and mixed culture was used to detect the bystander effect of the anti-CLDN18.2 antibody drug conjugate prepared in Example 5.

[0575] Positive and negative cells in the logarithmic growth phase were taken and the cell density was adjusted to 4×10 450 μL / well of each 96-well plate was added. The anti-CLDN18.2 antibody-drug conjugate was serially diluted with McCoy's 5A complete medium (GIBCO, catalog number 16600-082) containing 10% FBS and added to the 96-well plate at 50 μL / well. The starting concentration of the anti-CLDN18.2 antibody-drug conjugate was 33.3 nM, and the dilution series was repeated 5-fold for a total of 8 concentrations. The 96-well plate was incubated at 37°C, 5% CO2 for 120 hours. After incubation, 20 μL of IL-31 (R&D Systems, catalog number 2824-IL-010 / CF) was added to each well (final concentration 10 ng / mL) for stimulation and incubated in a 37°C, 5% CO2 incubator for 4-6 hours. After the incubation, 120 μL of Luciferase Assay Substrate (Vazyme, catalog number DD1201-02) was added to each well, and the chemiluminescence value was detected using a microplate reader, and the survival rate of the U2OS-Luciferase cells was calculated.

[0576] Data analysis was performed using GraphPad Prism 5, and the results are shown in Figure 6. The results showed that both hz28G3-1.1-DDDXd and hz28G3-1.3-DDDXd had significant bystander effects, and their killing activity against negative cells was comparable in the presence of positive cells.

[0577] Example 13 Pharmacokinetic Evaluation of Anti-CLDN18.2 Antibody Drug Conjugates in Rats

[0578] SD rats (160-180 g) (source: Experimental Animal Management Department of Shanghai Institute of Family Planning Sciences) were randomly divided into 3 groups, with 4 rats in each group, and 15F9-DDDXd, hz28G3-1.1-DDDXd and hz28G3-1.1-DDDXd prepared in Example 3 were intravenously injected at a dose of 10 mg / kg. Before and after administration, the SD rats were not fasted and had free access to water.

[0579] About 0.2 mL of blood was collected from the jugular vein 30 min, 2 h (±1 min), 8 h (±1 min), 24 h (±5 min), 48 h (±5 min), 4 d (±10 min), 7 d (±10 min), 10 d (±10 min), 14 d (±20 min), 21 d (±20 min), or 28 d (±20 min) after administration. The blood was anticoagulated with EDTA-K2 and centrifuged at 4°C, 4000 rpm, for 10 min to separate the plasma.

[0580] An appropriate volume of the separated plasma was aspirated and diluted to the minimum dilution factor (20-fold) with sample diluent (PBST containing 1% BSA). For samples requiring higher dilution, further dilute with sample diluent containing 5% blank rat plasma. Vortex until thoroughly mixed to obtain the test sample. The assay has a quantitation range of 19.53125 ng / mL to 2500 ng / mL. AffiniPure Goat Anti-Human IgG, F(ab')2 fragment specific (Jackson ImmunoResearch, 109-005-097) was diluted to a concentration of 1 μg / mL in PBS buffer (pH 7.4) and coated onto a 96-well plate at 100 μL / well. Incubate overnight at 4°C. Wash the 96-well plate with PBST (PBS containing 0.5% Tween-20), then add 200 μL / well of blocking solution (PBST containing 1% BSA) and block at room temperature for 2-3 hours. The blocking solution was discarded, and 100 μL / well of the diluted standard curve samples, quality control samples, and the above-mentioned test samples were added and incubated at room temperature for 2 hours. After washing the 96-well plate with PBST, Goat anti-Human Kappa Light Chain Cross-Adsorbed Secondary Antibody, HRP (Thermofisher, A18859) was added at a volume ratio of 1:10,000 and incubated at room temperature for 1 hour. After washing the 96-well plate with PBST, 100 μL / well of TMB solution (Tiangen, catalog number PA107-01) was added and incubated at room temperature in the dark for 14 minutes. The reaction was terminated with 1 M H2SO4. The absorbance values ​​were read at wavelengths of 450 nm / 630 nm using a Tecan Spark microplate reader, and the curve was fitted using a 4-parameter logistic fit.

[0581] The intravenous exposure of the anti-CLDN18.2 antibody-drug conjugate was evaluated by in vivo pharmacokinetics in rats, and the average pharmacokinetic parameters of the total antibody (including antibodies conjugated and unconjugated cytotoxic drugs) in each group of SD rats were calculated, including the peak concentration (C max ), peak time (T max ), area under the drug-time curve (AUC (0-t) ), elimination half-life (t 1 / 2 ), mean residence time (MRT (0-t) ) and clearance (CL), as shown in Table 6 below.

[0582] In terms of exposure, mean residence time and clearance in rats, hz28G3-1.1-DDDXd and hz28G3-1.3-DDDXd were comparable to the reference substance 15F9-DDDXd; however, the half-life of hz28G3-1.3-DDDXd was superior to that of hz28G3-1.1-DDDXd.

[0583] Table 6 Total anti-pharmacokinetic parameters (Mean ± SD)

[0584] Example 14 Pharmacodynamic Evaluation of Anti-CLDN18.2 Antibody Drug Conjugates in the NUGC-4 Human Gastric Cancer CB-17 SCID Mouse Xenograft Tumor Model

[0585] NUGC-4 human gastric cancer cells were subcutaneously inoculated into the right axilla of SPF female CB-17 SCID mice (source: Shanghai Lingchang Biotechnology Co., Ltd.) at a concentration of 5 × 10 6 When the average tumor volume reaches 150mm 3 When the reaction temperature was about 30 °C, the animals were divided into 3 groups with 6 animals in each group. The specific grouping and dosage are shown in Table 7. Among them, hz28G3-1.3-DDDXd and 15F9-DDDXd were both prepared as in Example 3 and measured by the DAR value of Example 4. The DAR value of hz28G3-1.3-DDDXd was 7.4, and the DAR value of 15F9-DDDXd was 7.7.

[0586] Table 7 Grouping and Dosage

[0587] The day of grouping was designated Day 0, and the drug was administered once via the tail vein on Day 2. Tumor volume was measured 2-3 times per week, and mice were weighed and recorded. The general condition of the mice was observed and recorded daily. At the end of the experiment, the tumors were removed, weighed, and photographed.

[0588] The detection indicators and calculation formulas are as follows:

[0589] Tumor volume, TV (mm 3 )=1 / 2×(a×b 2 ), where a is the long diameter of the tumor and b is the short diameter of the tumor.

[0590] Relative tumor volume, RTV = TV t / TV0; TV0 is the tumor volume on day 0, TV t is the tumor volume at each measurement.

[0591] Relative tumor growth rate, T / C (%) = T RTV / C RTV ×100%; where T RTV RTV for the treatment group, CRTV The vehicle control group was RTV.

[0592] Tumor growth inhibition rate, TGI (%) = (1-TW / TW0) × 100%; wherein, TW is the tumor weight of the treatment group, and TW0 is the tumor weight of the vehicle control group.

[0593] Body weight change rate, WCR (%) = (Wt t -Wt0) / Wt0×100%; where Wt0 is the weight of mice on day 0, Wt t is the weight of the mice at each measurement.

[0594] The results of the test indicators on the 33rd day are shown in Table 8 below. hz28G3-1.3-DDDXd had no obvious toxicity and had inhibitory activity against NUGC-4 human gastric cancer xenograft tumors in mice, which was comparable to the reference product 15F9-DDDXd.

[0595] Table 8 Effects of anti-CLDN18.2 antibody-drug conjugates on various indicators in the NUGC-4 human gastric cancer subcutaneous transplant tumor model in mice

[0596] Note: **p<0.01 compared with the vehicle control group

[0597] Example 15 Pharmacodynamic Evaluation of Anti-CLDN18.2 Antibody Drug Conjugates in the BxPC-3 Human Pancreatic Cancer CD-17 SCID Mouse Xenograft Model

[0598] SPF female CB-17 SCID mice (source: Shanghai Slake Laboratory Animal Co., Ltd.) were inoculated subcutaneously in the right axilla with BxPC-3 human pancreatic cancer tumors that highly expressed CLDN18.2. 3 When the reaction temperature was about 30 °C, the animals were divided into 3 groups with 4 animals in each group. The specific grouping and dosage are shown in Table 9. Among them, hz28G3-1.3-DDDXd and 15F9-DDDXd were both prepared as in Example 3 and measured by the DAR value of Example 4. The DAR value of hz28G3-1.3-DDDXd was 7.4, and the DAR value of 15F9-DDDXd was 7.7.

[0599] Table 9 Grouping and Dosage

[0600] The day of grouping was designated Day 0, and the drug was administered once intravenously through the tail vein. Tumor volume was measured 2-3 times per week, and the mice were weighed and recorded. The general condition of the mice was observed and recorded daily. At the end of the experiment, the tumors were removed, weighed, and photographed.

[0601] The detection indicators and calculation formulas are as follows:

[0602] Tumor volume, TV (mm 3 )=1 / 2×(a×b 2 ), where a is the long diameter of the tumor and b is the short diameter of the tumor.

[0603] Relative tumor volume, RTV = TV t / TV0; TV0 is the tumor volume on day 0, TV t is the tumor volume at each measurement.

[0604] Relative tumor growth rate, T / C (%) = T RTV / C RTV ×100%; where T RTV RTV for the treatment group, C RTV The vehicle control group was RTV.

[0605] Tumor growth inhibition rate, TGI (%) = (1-TW / TW0) × 100%; wherein, TW is the tumor weight of the treatment group, and TW0 is the tumor weight of the vehicle control group.

[0606] Body weight change rate, WCR (%) = (Wt t -Wt0) / Wt0×100%; where Wt0 is the weight of the animal on day 0, Wt t is the animal weight at each measurement.

[0607] The test results of various indicators on the 21st day are shown in Table 10 below. hz28G3-1.3-DDDXd had no obvious toxicity and had a significant inhibitory effect on BxPC-3 human pancreatic cancer CB-17SCID mouse xenograft tumors with high expression of CLDN18.2, which was better than the reference product 15F9-DDDXd.

[0608] Table 10 Effects of anti-CLDN18.2 antibody-drug conjugates on various indicators in the BxPC-3 human pancreatic cancer subcutaneous transplant tumor model in mice

[0609] Note: **p<0.01 compared with the vehicle control group

[0610] Example 16 Preparation of anti-CLDN18.2 antibody drug conjugate

[0611] Reagents:

[0612] Antibody: anti-CLDN18.2 antibody hz28G3-1.3 prepared in Example 1;

[0613] Linker-payload: Compound H (MC-GGFG-DDDXd) prepared in Example 2.

[0614] Experimental process:

[0615] 1. Antibody Reduction: The antibody was replaced in histidine buffer (L-histidine 1.43 mg / mL, L-histidine hydrochloride monohydrate 2.27 mg / mL) at pH 6.0. The antibody concentration was adjusted to 10 mg / mL with histidine buffer (pH 6.0), and the pH was adjusted to 6.3. A stock solution of ethylenediaminetetraacetic acid disodium salt (EDTA·Na2) was added to a final concentration of 5 mM. This solution was placed in a light-proof glass bottle. When the solution temperature rose to 30°C, 10 mM TCEP solution was added to the solution to achieve a molar ratio of antibody to TCEP of 1:8. The solution was incubated in the dark at 30°C for 100 minutes with stirring to reduce the interchain disulfide bonds of the antibody, thereby obtaining reaction solution 1.

[0616] 2. Coupling of the Antibody and Linker-Payload: After the temperature of reaction solution 1 was lowered to 22°C, DMSO solution was added (DMSO solution: reaction solution 1 (v / v) = 1:20) and mixed thoroughly. A 10 mg / mL linker-payload solution dissolved in DMSO was added to adjust the molar ratio of the antibody to the linker-payload to 1:9.5. The mixture was incubated in the dark at 22°C for 2 hours with gentle stirring to connect the antibody and linker-payload to obtain reaction solution 2.

[0617] 3. Coupling termination and purification: The reaction solution 2 was ultrafiltered with a pH 6.0 histidine buffer to obtain the anti-CLDN18.2 antibody-drug conjugate hz28G3-1.3-DDDXd.

[0618] The structure of the prepared hz28G3-1.3-DDDXd is:

[0619] The measured DAR value is 7.93, of which D8 accounts for 97.04% and D0 to D7 account for 2.96%; the proportions are based on molar amounts.

[0620] The sequence information of the present disclosure is summarized in Table S2 below.

[0621] Table S2 Sequence information

[0622] For the purposes of description and disclosure, all patents, patent applications and other identified publications are expressly incorporated herein by reference. These publications are provided solely because their disclosure predates the filing date of the present disclosure. All statements regarding the dates of these documents or representations of the contents of these documents are based on information available to the applicant and do not constitute any admission as to the correctness of the dates of these documents or the contents of these documents. Furthermore, any citation of these publications herein does not constitute an admission that such publications are part of the common general knowledge in the art in any country.

[0623] Although the present disclosure has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications or improvements may be made based on the present disclosure. Therefore, such modifications or improvements, which do not depart from the spirit of the present disclosure, are intended to be within the scope of protection claimed herein.

Claims

1. A general formula of Ab-(LU) n The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof, wherein Ab is an antibody or an antigen-binding fragment thereof, L is a linker, U is a cytotoxic drug, and n is an integer selected from 1-10, wherein, The Ab is an anti-CLDN18.2 antibody or an antigen-binding fragment thereof, which comprises HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3, wherein: (1) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 3, 5, 7, 8, 9, and 10, respectively; (2) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 3, 4, 7, 8, 9, and 10, respectively; (3) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 3, 6, 7, 8, 9, and 10, respectively; (4) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 20, 24, 25, 26, and 27, respectively; (5) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 21, 24, 25, 26, and 27, respectively; (6) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 22, 24, 25, 26, and 27, respectively; (7) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 23, 24, 25, 26, and 27, respectively; (8) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 20, 24, 25, 26, and 28, respectively; (9) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 21, 24, 25, 26, and 28, respectively; (10) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 22, 24, 25, 26, and 28, respectively; (11) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 19, 23, 24, 25, 26, and 28, respectively; (12) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 comprise the amino acid sequences set forth in SEQ ID NOs: 37, 38, 39, 40, 41, and 42, respectively; (13) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise the amino acid sequences of SEQ ID NOs: 45, 46, 47, 48, 49 and 50, respectively; or (14) HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 comprise the amino acid sequences shown in SEQ ID NOs: 53, 54, 55, 56, 57 and 58, respectively.

2. The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to claim 1, wherein the anti-CLDN18.2 antibody or antigen-binding fragment thereof comprises a heavy chain variable region and a light chain variable region, wherein: (1) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 14 and 17, respectively; (2) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 12 and 17, respectively; (3) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 13 and 17, respectively; (4) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 11 and 16, respectively; (5) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 15 and 17, respectively; (6) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 12 and 18, respectively; (7) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 13 and 18, respectively; (8) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 14 and 18, respectively; (9) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 15 and 18, respectively; (10) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 29 and 34, respectively; (11) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 30 and 35, respectively; (12) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 31 and 35, respectively; (13) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 32 and 35, respectively; (14) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 33 and 35, respectively; (15) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 30 and 36, respectively; (16) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 31 and 36, respectively; (17) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 32 and 36, respectively; (18) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 33 and 36, respectively; (19) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 43 and 44, respectively; (20) the heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences set forth in SEQ ID NOs: 51 and 52, respectively; or (21) The heavy chain variable region and the light chain variable region comprise amino acid sequences that are at least 80% identical to the amino acid sequences shown in SEQ ID NOs: 59 and 60, respectively.

3. The antibody-drug conjugate or pharmaceutically acceptable salt or solvate thereof according to claim 1 or 2, wherein the anti-CLDN18.2 antibody or antigen-binding fragment thereof is of IgG1, IgG2 or IgG4 isotype.

4. The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to any one of claims 1 to 3, wherein the anti-CLDN18.2 antibody further comprises a heavy chain constant region and a light chain constant region, wherein the heavy chain constant region comprises the amino acid sequence of SEQ ID NO: 1 or an amino acid sequence having 1, 2, 3, 4 or 5 amino acid substitutions, deletions or additions compared to the amino acid sequence of SEQ ID NO: 1, and the light chain constant region comprises the amino acid sequence of SEQ ID NO: 2 or an amino acid sequence having 1, 2, 3, 4 or 5 amino acid substitutions, deletions or additions compared to the amino acid sequence of SEQ ID NO:

2.

5. The antibody drug conjugate according to any one of claims 1 to 3, or a pharmaceutically acceptable salt or solvate thereof, wherein the anti-CLDN18.2 antibody comprises a heavy chain and a light chain, wherein (1) the heavy chain comprises an amino acid sequence that is at least 80% identical to the amino acid sequence of SEQ ID NO: 63, and the light chain comprises an amino acid sequence that is at least 80% identical to the amino acid sequence of SEQ ID NO: 64; or (2) The heavy chain comprises an amino acid sequence that is at least 80% identical to the amino acid sequence shown in SEQ ID NO: 61, and the light chain comprises an amino acid sequence that is at least 80% identical to the amino acid sequence shown in SEQ ID NO:

62.

6. The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to any one of claims 1 to 5, wherein U is a camptothecin-type topoisomerase I inhibitor, and L and / or U are deuterated; preferably, U is SN-38, an SN-38 derivative, exatecan, or an exatecan derivative; more preferably, U is an exatecan derivative.

7. The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to claim 6, wherein -U is a structure represented by the following formula Ia:

8. The antibody-drug conjugate or pharmaceutically acceptable salt or solvate thereof according to claim 6 or 7, wherein -L- is a structure represented by the following formula IIa: in, R1 and R2 are each independently selected from hydrogen or deuterium; Furthermore, the 3-position of -(succinimide-3-yl-N)- in the structure shown is connected to the Ab, and the methylene group at the other end is connected to the U.

9. The antibody-drug conjugate or pharmaceutically acceptable salt or solvate thereof according to claim 1 or 6, wherein -LU is a structure represented by the following formula IIIa: in, R1 and R2 are each independently selected from hydrogen or deuterium.

10. The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to claim 9, wherein -LU is a structure represented by the following formula IIIa-1, IIIa-2, IIIa-3 or IIIa-4:

11. The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to claim 1 or 6, wherein the structure of the antibody-drug conjugate is shown in the following formula IV: in, R1 and R2 are each independently selected from hydrogen or deuterium.

12. The antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to claim 11, wherein the structure of the antibody-drug conjugate is represented by the following formula IV-1, IV-2, IV-3 or IV-4:

13. The antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof according to any one of claims 1 to 12, wherein: Said n is an integer selected from 1-10, 1-9, 1-8, 2-8, 2-7, 2-6, 2-5, 2-4, 2-3, 3-8, 3-7, 3-6, 3-5, 3-4, 4-8, 4-7, 4-6, 4-5, 5-8, 5-7, 5-6, 6-8, 6-7 or 7-8, preferably an integer selected from 2-8, 3-8, 4-8, 5-8, 6-8 or 7-8, more preferably an integer selected from 6-8.

14. The antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof according to any one of claims 1 to 13, wherein: The antibody drug conjugate or a pharmaceutically acceptable salt or solvate thereof exhibits one or a combination of the following properties: (a) Binding to CLDN18.2; (b) blocking the binding of CLDN18.2 to its ligand; (c) Demonstrates endocytosis in cells expressing CLDN18.2; (d) has cytotoxic activity against tumor cells expressing CLDN18.2; (e) has a bystander effect; (f) having ADCC activity; (g) having CDC activity; (h) does not bind to CLDN18.1; (i) does not bind to cells that do not express CLDN18.2; and (j) No ADCC and / or CDC activity against cells expressing CLDN18.

1.

15. A pharmaceutical composition comprising the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof according to any one of claims 1 to 14; preferably, the antibody-drug conjugate or a pharmaceutically acceptable salt or solvate thereof in the pharmaceutical composition is heterogeneous or homogeneous; optionally, the pharmaceutical composition further comprises a pharmaceutically acceptable carrier.

16. The pharmaceutical composition according to claim 15, wherein The antibody drug conjugate or pharmaceutically acceptable salt or solvate thereof in the pharmaceutical composition is heterogeneous and has a DAR of 0-10, 0-9, 0-8, 1-10, 1-9, 1-8, 2-10, 2-9, 2-8, 3-8, 4-8, 5-8, 6-8, 7-8, 7.2-8, 7.4-8, 7.5-8, 7.6-8, 7.7-8, 7.8-8, 7.8-7.9 or 7.9-8; preferably 7-8, 7.2-8, 7.4-8, 7.6-8, 7.7-8; more preferably about 7.1, about 7.2, about 7.4, about 7.6, about 7.7 or about 8.

17. The antibody-drug conjugate according to any one of claims 1 to 14, or a pharmaceutically acceptable salt or solvate thereof, or the pharmaceutical composition according to claim 15 or 16, for treating tumors; Optionally, the antibody drug conjugate, or a pharmaceutically acceptable salt or solvate thereof, or pharmaceutical composition is combined with a second or additional therapeutic agent.

18. The antibody-drug conjugate or pharmaceutically acceptable salt or solvate thereof, or pharmaceutical composition for use according to claim 17, wherein: The tumor is a CLDN18.2-positive tumor; preferably, the tumor is gastric cancer, esophageal cancer, gastrointestinal cancer, pancreatic cancer, liver cancer, lung cancer, bronchial cancer, mesothelioma, kidney cancer, ovarian cancer, breast cancer, bladder cancer, uterine cancer, endometrial cancer, prostate cancer, testicular cancer, anal cancer, vaginal cancer, bile duct cancer, gallbladder cancer, head and neck cancer, spinal tumor, otolaryngology tumor, thyroid cancer, mesothelioma, bone cancer, skin cancer, melanoma, adenocarcinoma, sarcoma, neuroblastoma, glioblastoma, brain cancer, central nervous system cancer, neuroendocrine tumor, leukemia, lymphoma and myeloma.

19. A method for preparing the antibody-drug conjugate according to any one of claims 11 to 14, or a pharmaceutically acceptable salt or solvate thereof, comprising treating an anti-CLDN18.2 antibody or an antigen-binding fragment thereof under reducing conditions, and then reacting the anti-CLDN18.2 antibody or the antigen-binding fragment thereof with a linker-payload selected from the structure represented by Formula III, wherein: The structure shown in formula III is as follows: Wherein, R1 and R2 are independently selected from hydrogen or deuterium.

20. The method according to claim 19, wherein R1 and R2 are hydrogen.

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