Anti-Claudin 18.2 antibody and its use

Abstract

The present invention relates to novel antibodies and antibody fragments that specifically bind to Claudin18.2, and compositions containing said antibodies or antibody fragments. The present invention also relates to nucleic acids encoding said antibodies or antibody fragments, host cells containing them, and related uses. The present invention also relates to therapeutic and diagnostic uses of these antibodies and antibody fragments.

Description

[Background technology]

[0001] This application is based on and claims priority from the application with CN application number 202010570517.X and filing date June 19, 2020, and the contents disclosed in said CN application are incorporated into this application as a whole.

[0002] This invention relates to novel antibodies and antibody fragments that specifically bind to Claudin 18.2, and compositions containing said antibodies or antibody fragments. Furthermore, this invention relates to nucleic acids encoding said antibodies or antibody fragments, host cells containing them, and related uses. Moreover, this invention relates to the therapeutic and diagnostic uses of these antibodies and antibody fragments.

[0003] Claudins are a family of proteins that are essential components of tight junctions in cells. They establish intercellular barriers that control molecular movement between cells. Claudins family proteins have four transmembrane domains, with both their N-terminus and C-terminus located in the cytoplasm. Different Claudins proteins are expressed in different tissues, and alterations in their function are associated with cancer development in each tissue. For example, Claudin-1 is expressed in colorectal cancer and has prognostic value, Claudin-18 is expressed in gastric cancer, and Claudin-10 is expressed in hepatocellular carcinoma. As cell membrane surface proteins, Claudins are useful targets for various therapeutic strategies.

[0004] Claudin-18 isotype 2 (Claudin 18.2 or CLDN18.2) is a highly selective cell lineage marker. Its expression in normal tissue is strictly limited to differentiated epithelial cells of the gastric mucosa, but not in the gastric stem cell region. CLDN18.2 is expressed in a considerable number of primary gastric cancers and maintains its expression level in cancerous tissue of gastric metastases. In addition to gastric cancer, CLDN18.2 expression is also found in pancreatic cancer, making it an ideal target molecule for treating these cancers (Singh, P., Toom, S. & Huang, Y. Anti-CLDN18.2 antibody as new targeted therapy for advanced gastric cancer. J Hematol Oncol 10, 105 (2017). https: / / doi.org / 10.1186 / s13045-017-0473-4).

[0005] Given the large number of unsatisfied clinical oncology treatment needs, drugs targeting Claudin18.2 are in great need. While several monoclonal antibodies targeting Claudin18.2 have already been developed using conventional technology, many of these antibodies are chimeric, potentially carry a relatively high risk of immunogenicity, have relatively low affinity, poor specificity, and generally exhibit ADCC activity.

[0006] Therefore, there is a need to further develop new antibodies targeting Claudin18.2 that have relatively low immunogenicity, stronger binding affinity to Claudin18.2, better specificity, strong ADCC and CDC activity, and better antitumor activity. [Overview of the project]

[0007] In some embodiments, the present invention relates to an antibody or antigen-binding fragment that conjugates to CLDN18.2, comprising three heavy chain variable region CDRs and three light chain variable region CDRs as described in the present invention.

[0008] In some embodiments, the antibody or antigen-binding fragment that binds to CLDN18.2 according to the present invention comprises the heavy chain variable region and / or light chain variable region described in the present invention.

[0009] In some embodiments, the antibody or antigen-binding fragment conjugating CLDN18.2 according to the present invention further comprises the heavy chain constant region and / or light chain constant region described in the present invention.

[0010] In some aspects, the present invention further relates to the following embodiments.

[0011] 1. An antibody or antigen-binding fragment that binds to CLDN18.2 according to the present invention, wherein the antibody is an antibody or antigen-binding fragment in IgG1 form, IgG2 form, IgG3 form, or IgG4 form, and preferably an antibody or antigen-binding fragment in IgG1 form.

[0012] 2. An antibody or antigen-binding fragment thereof that binds to CLDN18.2 according to the present invention, wherein the antibody is a monoclonal antibody.

[0013] 3. An antibody or antigen-binding fragment thereof that conjugates to CLDN18.2 according to the present invention, wherein the antibody is a humanized antibody, a human antibody, or a chimeric antibody.

[0014] 4. An antibody or antigen-binding fragment thereof that conjugates to CLDN18.2 according to the present invention, wherein the antigen-binding fragment is selected from antibody fragments such as Fab, Fab', Fab'-SH, Fv, single-chain antibody (e.g., scFv), (Fab')2, single-domain antibody (e.g., VHH), dAb (domain antibody), or linear antibody.

[0015] 5. An antibody or antigen-binding fragment thereof that conjugates to CLDN18.2 according to the present invention, wherein the antibody or antigen-binding fragment thereof is (i) It binds to CLDN18.2 (e.g., human CLDN18.2) with high affinity but does not bind to CLDN18.1 (e.g., human CLDN18.1). (ii) It has an equilibrium dissociation constant (K D ) that is less than about 15 nM, preferably about 10 nM, 9.5 nM, 9 nM, 8.5 nM, 8 nM, 7.5 nM, 7 nM, 6.5 nM, 6 nM, 5.5 nM, 5 nM, 4.5 nM, 4 nM, 3.5 nM, 3 nM or less, and binds to human CLDN18.2. (iii) It binds to cell surface CLDN18.2 but does not bind to cell surface CLDN18.1. (iv) It has ADCC activity or CDC activity, e.g., ADCC activity or CDC activity corresponding to a known antibody (e.g., Zmab), or has ADCC activity or CDC activity that is greater than that. (v) It suppresses tumor cells, e.g., tumor cells expressing CLDN18.2. (vi) It can effectively suppress tumor growth, and the tumor suppression rate is about 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65% or 70% or more. It has one or more of the above properties.

[0016] 6. An isolated nucleic acid encoding a light chain variable region or a heavy chain variable region, or a light chain or a heavy chain, in an antibody or an antigen-binding fragment thereof that binds to CLDN18.2 according to the present invention.

[0017] 7. A vector containing the nucleic acid according to the present invention, preferably, the vector is an expression vector.

[0018] 8. A host cell containing the nucleic acid or vector according to the present invention, preferably, the host cell is a prokaryotic or eukaryotic cell, more preferably, a yeast cell, a mammalian cell (e.g., 293 cells or CHO cells, e.g., CHO-S or HEK293 cells), or other cells applicable to the preparation of an antibody or an antigen-binding fragment thereof.

[0019] 9. A method for preparing an antibody or an antigen-binding fragment thereof that binds to CLDN18.2, comprising culturing the host cell of the present invention under conditions suitable for the expression of a nucleic acid encoding the antibody or an antigen-binding fragment thereof that binds to CLDN18.2 according to the present invention, and optionally isolating the antibody or an antigen-binding fragment thereof, and further optionally recovering the antibody or an antigen-binding fragment thereof that binds to CLDN18.2 from the host cell.

[0020] 10. An immune complex comprising an antibody or an antigen-binding fragment thereof that binds to CLDN18.2 according to the present invention and another substance such as a cytotoxic agent.

[0021] 11. A pharmaceutical composition comprising an antibody or an antigen-binding fragment thereof that binds to CLDN18.2 according to the present invention or the immune complex of the present invention, and optionally one or more other therapeutic agents, such as chemotherapeutic agents, cytokines, cytotoxic agents, other antibodies, small molecule drugs and immunomodulators, and optionally pharmaceutical adjuvants.

[0022] 12. A pharmaceutical combination comprising an antibody or an antigen-binding fragment thereof that binds to CLDN18.2 according to the present invention or the immune complex of the present invention and one or more other therapeutic agents, such as chemotherapeutic agents, cytokines, cytotoxic agents, other antibodies, small molecule drugs and immunomodulators.

[0023] 13. A method for preventing or treating a tumor in a subject, comprising administering to the subject an effective amount of an antibody or an antigen-binding fragment thereof that binds to CLDN18.2 according to the present invention, or the immune complex, pharmaceutical composition or pharmaceutical combination according to the present invention.

[0024] 14. A method for inducing ADCC and / or CDC in a subject, comprising administering to the subject an effective amount of an antibody or an antigen-binding fragment thereof that binds to CLDN18.2 according to the present invention, or the immune complex, pharmaceutical composition or pharmaceutical combination according to the present invention.

[0025] 15. Use of the antibody or immune complex of the present invention in the preparation of a pharmaceutical composition or pharmaceutical combination for preventing or treating tumors and / or inducing ADCC and / or CDC.

[0026] 16. A method or use of the present invention, wherein the tumor is cancer, and preferably the cancer has elevated levels (e.g., nucleic acid or protein levels) of CLDN18.2.

[0027] 17. A method of the present invention further comprising administering to a patient one or more therapies, e.g., a treatment scheme and / or other therapeutic agents, preferably, the treatment scheme comprising surgical treatment and / or radiotherapy, and the other therapeutic agent being selected from chemotherapeutic agents, cytokines, cytotoxic agents, other antibodies, small molecule drugs, or immunomodulators.

[0028] 18. Use of the present invention, wherein the pharmaceutical or pharmaceutical combination may be administered to a subject in combination with one or more therapies, e.g., a treatment scheme and / or other therapeutic agents, preferably the treatment scheme comprising surgical treatment and / or radiotherapy, and the other therapeutic agent being selected from chemotherapeutic agents, cytokines, cytotoxic agents, other antibodies, small molecule drugs, or immunomodulators.

[0029] 19. A method for detecting CLDN18.2 in a sample, (a) Contacting a sample with the antibody or antigen-binding fragment according to the present invention, (b) A method comprising detecting the formation of a complex of the antibody or its antigen-binding fragment with CLDN18.2, wherein the antibody is optionally labeled for detection. [Brief explanation of the drawing]

[0030] [Figure 1] This demonstrates that the anti-CLDN18.2 antibody specifically binds to CLDN18.2 on the cell surface. [Figure 2] This indicates that the anti-CLDN18.2 antibody does not bind to CLDN18.1 on the cell surface. [Figure 3] This demonstrates the ADCC activity of the anti-CLDN18.2 antibody against CHO-hCLDN18.2 via a reporter gene. [Figure 4] This demonstrates the ADCC activity of a humanized anti-CLDN18.2 antibody against CHO-hCLDN18.2 via a reporter gene. [Figure 5] This study demonstrates the binding of the anti-CLDN18.2 antibody to the gastric cancer cell line NUGC-4, the gastric cancer cell line KATO III-hCLDN18.2, and the pancreatic cancer cell line DAN-G-hCLDN18.2. [Figure 6] This shows the detection of CDC activity by the anti-CLDN18.2 antibody. [Figure 7] This shows the detection of ADCC activity by the anti-CLDN18.2 antibody. [Figure 8] This study demonstrates the antitumor effect of the anti-CLDN18.2 antibody in a mouse model of pancreatic cancer. [Figure 9] Figure showing the antitumor effect of anti-CLDN18.2 antibody in a mouse model of gastric cancer. [Modes for carrying out the invention]

[0031] I. Definition Before describing the present invention in detail, it should be understood that the present invention is not limited to the specific methodologies, forms, or reagents described herein, as these may be modified. Furthermore, the terms used in this invention are merely for the purpose of describing specific embodiments and are not intended to limit the scope of the invention; the scope of the invention is understood to be limited solely by the claims. Unless otherwise defined, the technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art.

[0032] The following definitions are used to interpret this specification, and where appropriate, a singular term may include a plural form, and vice versa. It should be understood that the terms used herein are merely descriptive and not limiting to specific embodiments.

[0033] The term "approximately," when used with a number, means that the number includes a range that is 5% smaller than the specified number as the lower limit and 5% larger than the specified number as the upper limit.

[0034] As used herein, the terms "and / or" refer to any one of the selectable options, or to two or more of the selectable options.

[0035] As used herein, the terms “contains” or “includes” mean including, but not excluding, any other elements, integers, or steps. Where the terms “contains” or “includes” are used herein, unless otherwise specified, they also include combinations of the other elements, integers, or steps. For example, when it is said that an antibody variable region of a particular sequence “contains,” it is also intended to include the antibody variable region consisting of that particular sequence.

[0036] As used herein, the terms "CLAUDIN" or "CLDN" refer to the most important skeletal proteins that determine the tight junction structure between cells, participating in adhesion junctions and playing a crucial role in tumor cell metastasis and invasion. Claudin proteins are widely present in mammalian epithelial and endothelial cells, primarily distributed on the lateral surfaces of epithelial cells and the basal cytoplasmic membrane. Different Claudin proteins have specific expression in different tissues, among which the Claudin18 (CLDN18) gene is located at 3q22.3, has a molecular weight of 24 kDa, contains 261 amino acid residues, belongs to the Claudins superfamily, and its protein structure consists of two extracellular loops and four membrane-permeable regions. The two subtypes of the human CLDN18 or Claudin18 protein are Claudin18.1 or CLDN18.1 (UniProt ID: P56856-1) and Claudin18.2 or CLDN18.2 (UniProt ID: P56856-2), respectively. In the primary structural sequences of both proteins, they differ only in amino acid residues at a certain position from the N-terminal signal peptide to the extracellular loop 1 structure. Specifically, on the extracellular loop 1, CLDN18.1 and CLDN18.2 differ by only eight amino acids. The interspecies sequence homology between the two subtype proteins of CLDN18 is also very high. Of these, the extracellular loop 1 of CLDN18.2 has a perfect sequence match in different organisms such as humans, mice, and rhesus monkeys, and the homology between human and mouse CLDN18.2 proteins reaches 84%, revealing that the CLDN18.2 protein sequence is extremely conserved (O. Tureci et al., Gene 481:83-92, 2011). CLDN18.2 or any of its variants and isotypes can be isolated from cells or tissues that express them naturally, or produced by recombinant methods well known in the art and / or the methods described herein. In one embodiment, the CLDN18.2 described herein is human CLDN18.2.

[0037] As used herein, the terms “anti-CLDN18.2 antibody,” “anti-CLDN18.2,” “CLDN18.2 antibody,” or “antibody that binds to CLDN18.2” refer to an antibody that can be used as a therapeutic agent targeting (human) CLDN18.2 by binding to (human) CLDN18.2 with sufficient affinity. In one embodiment, the (human) CLDN18.2 antibody binds to (human) CLDN18.2 with high affinity in vitro or in vivo. In one embodiment, the (human) CLDN18.2 antibody does not bind to CLDN18.1. In one embodiment, the (human) CLDN18.2 antibody binds to cells expressing CLDN18.2 but not to cells expressing CLDN18.1. In some embodiments, the binding is measured, for example, by radioimmunoassay (RIA), biolayer interferometry (BLI), MSD assay, surface plasmon resonance (SPR), or flow cytometry.

[0038] The term "antibody fragment" refers to a portion of a complete antibody. In preferred embodiments, the antibody fragment is an antigen-binding fragment.

[0039] An "antigen-binding fragment" refers to a molecule that contains part of a complete antibody and binds to the antigen to which the complete antibody binds, but is a molecule distinct from the complete antibody. Examples of antibody fragments include, but are not limited to, Fv, Fab, Fab', Fab'-SH, F(ab')2, dAb (domain antibody), linear antibodies, single-chain antibodies (e.g., scFv), single-domain antibodies (e.g., VHH), bivalent antibodies or fragments thereof, or camelid antibodies.

[0040] The term "antigen" refers to a molecule that triggers an immune response. Such an immune response may involve antibody production, activation of specific immune cells, or both. Those skilled in the art will understand that virtually all large molecules, including proteins or peptides, can be used as antigens. Antigens may also be derived from recombinant DNA or genomic DNA. As used herein, the term "epitope" refers to a portion of an antigen (e.g., CLDN18.2) that specifically interacts with antibody molecules.

[0041] An antibody that "binds to the same or overlapping epitopes as the reference antibody" is an antibody that inhibits 50%, 60%, 70%, 80%, 90%, or 95% or more of the binding of the reference antibody to its antigen in competitive testing. Conversely, the reference antibody inhibits 50%, 60%, 70%, 80%, 90%, or 95% or more of the binding of the reference antibody to its antigen in competitive testing.

[0042] An antibody that competitively binds to its antigen with a reference antibody is an antibody that inhibits 50%, 60%, 70%, 80%, 90%, or 95% or more of the binding of the reference antibody to its antigen in a competitive assay. Conversely, the reference antibody inhibits 50%, 60%, 70%, 80%, 90%, or 95% or more of the binding of the reference antibody to its antigen in a competitive assay. Various competitive binding assays are available to determine whether one antibody competes with another, and these assays include, for example, solid-phase direct or indirect radioimmunoassay (RIA), solid-phase direct or indirect enzyme immunoassay (EIA), and sandwich competitive assays.

[0043] An antibody that inhibits the binding of a reference antibody to its antigen (e.g., competitive inhibition) is an antibody that inhibits the binding of the reference antibody to its antigen by 50%, 60%, 70%, 80%, 90%, or 95% or more. Conversely, the reference antibody inhibits the binding of the reference antibody to its antigen by 50%, 60%, 70%, 80%, 90%, or 95% or more. The binding of an antibody to its antigen can be measured by affinity (e.g., equilibrium dissociation constant). Methods for measuring affinity are well known in this field.

[0044] An antibody exhibiting similar or comparable binding affinity and / or specificity to a reference antibody is one having at least 50%, 60%, 70%, 80%, 90%, or 95% or more of the binding affinity and / or specificity of the reference antibody. This can be measured by any known method for measuring binding affinity and / or specificity in this field.

[0045] The "complementarity-determining region," "CDR region," or "CDR" is a region within the antibody variable domain that is hypervariable in sequence and contains predetermined loops ("hypervariable loops") and / or antigen contact residues ("antigen contact sites") that are structurally formed. CDRs primarily play a role in binding to antigen epitopes. Heavy chain and light chain CDRs are usually called CDR1, CDR2, and CDR3, and are numbered sequentially from the N-terminus. CDRs located within the heavy chain variable domain of an antibody are called HCDR1, HCDR2, and HCDR3, while CDRs located within the light chain variable domain of an antibody are called LCDR1, LCDR2, and LCDR3. In the amino acid sequence of a given light chain variable region or heavy chain variable region, the precise amino acid sequence boundary of each CDR can be accurately determined by one or a combination of many known antibody CDR assignment systems, such as Chothia (Chothia et al. (1989) Nature 342:877-883, Al-Lazikani et al., "Standard conformations for the canonical structures of immunoglobulins", Journal of Molecular Biology, 273, 927-948 (1997)), which is based on the three-dimensional structure of the antibody and the topology of the CDR loop; Kabat (Kabat et al., Sequences of Proteins of Immunological Interest, 4th edition, USD Department of Health and Human Services, National Institutes of Health (1987)), AbM (University of Bath), Contact (University College London), and the international ImMunoGeneTics. The database (IMGT) (available at www.imgt.cines.fr / ) includes a North CDR definition based on affinity propagation clustering, which utilizes a large number of crystal structures.

[0046] For example, depending on the CDR determination scheme, the residues of each CDR are as follows:

[0047] [Table 1]

[0048] The CDR may be determined by having the same Kabat numbering position as the sequence of reference CDRs (e.g., any one of the exemplary CDRs of the present invention).

[0049] Unless otherwise specified, in this invention, the terms "CDR" or "CDR sequence" include a CDR sequence determined by any one of the methods described above.

[0050] Unless otherwise specified, in this invention, when referring to residue positions in the antibody variable region (including heavy chain variable region residues and light chain variable region residues), it refers to the numbered positions based on the Kabat numbering system (Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991)).

[0051] In one embodiment, the heavy chain variable region (CDR) of the antibody according to the present invention is determined by the following rules.

[0052] VH CDR1 is determined by the AbM rule, while VH CDR2 and VH CDR3 are both determined by the Kabat rule.

[0053] In one embodiment, the light chain variable region (CDR) of the antibody according to the present invention is determined by the Kabat rule.

[0054] In one embodiment, the heavy chain variable region CDR of the antibody according to the present invention is determined by the AbM rule for VH CDR1, by the Kabat rule for both VH CDR2 and VH CDR3, and by the Kabat rule for the light chain variable region CDR.

[0055] It should be noted that the CDR boundaries of the variable region of the same antibody obtained by different assignment systems may differ. That is, there are differences in the CDR sequences of the variable region of the same antibody as defined by different assignment systems. Therefore, when an antibody is limited by a specific CDR sequence as defined in the present invention, the range of the antibody may also include antibodies whose variable region sequence includes the specific CDR sequence, but whose CDR boundary differs from the specific CDR boundary defined in the present invention because a different approach (e.g., different rules or combinations of assignment systems) is used.

[0056] Antibodies with different specificities (i.e., targeting different binding sites of different antigens) have different CDRs (Cellular Derived Sequences) (within the same assignment system). However, despite the difference in CDRs among antibodies, the number of amino acid positions directly involved in antigen binding in a CDR is limited. At least two of the Kabat, Chothia, AbM, Contact, and North methods can be used to determine the minimum overlapping region and provide a "minimal binding unit" for antigen binding. The minimal binding unit may be a subpart of the CDR. As is known to those skilled in the art, the residues of the remaining CDR sequence can be determined by the antibody structure and protein folding. Accordingly, the present invention also considers variants of any CDR provided herein. For example, in a variant of a CDR, the amino acid residues of the minimal binding unit may remain unchanged, while the remaining CDR residues, defined based on Kabat or Chothia, may be replaced with conserved amino acid residues.

[0057] The term "Fc region" is used herein to define the constant CH2 and CH3 regions of immunoglobulin heavy chains, and this term includes both native sequence Fc regions and mutant Fc regions. Fc regions can bind to different Fc receptors on the surface of immune cells and can induce CDC / ADCC / ADCP effect functions. Such effector functions are generally determined by the association between the Fc region and the binding domain (e.g., the antibody variable domain), which can be evaluated, for example, by several types of measurement methods disclosed herein.

[0058] An "IgG-type antibody" refers to the IgG form to which the antibody's heavy chain constant region belongs. All antibodies of the same type have the same heavy chain constant region, while antibodies of different types have different heavy chain constant regions. For example, an IgG4-type antibody means that its heavy chain constant region originates from IgG4, and an IgG1-type antibody means that its heavy chain constant region originates from IgG1.

[0059] A “humanized” antibody refers to an antibody that contains amino acid residues from non-human CDRs and amino acid residues from human FRs. In some embodiments, a humanized antibody contains at least one, generally two, of almost all variable domains, of which all or almost all CDRs (e.g., CDRs) correspond to portions derived from a non-human antibody, and all or almost all FRs correspond to portions derived from a human antibody. A humanized antibody may also contain at least a portion of the antibody constant region derived from a human antibody. The “humanized form” of an antibody (e.g., a non-human antibody) refers to an antibody that has undergone humanization.

[0060] "Human antibody," "whole human antibody," or "fully human antibody" refers to an antibody that may be used interchangeably, is produced from a human or human cell, or is derived from a non-human source, and has an amino acid sequence corresponding to the amino acid sequence of an antibody whose sequence is encoded in a human antibody library or other human antibody. This definition of human antibody explicitly excludes humanized antibodies that contain non-human antigen-binding residues.

[0061] As used herein, the terms “binding” or “specifically binding” mean that the binding action is selective to the antigen and can be distinguished from undesirable or nonspecific interactions. The ability of an antigen-binding site to bind to a specific antigen can be measured by enzyme-linked immunosorbent assay (ELISA) or by other known and common binding assays in this art, such as radioimmunoassay (RIA), biolayer interferometry, MSD assay, or surface plasmon resonance (SPR).

[0062] An "immune complex" is an antibody that has been combined with one or more other substances (including, but not limited to, cytotoxic agents or labels).

[0063] As used herein, the term “therapeutic agent” includes any substance effective in treating or preventing tumors such as cancer, and includes chemotherapeutic agents, cytokines, cytotoxic agents, other antibodies, small molecule drugs, or immunomodulators (e.g., immunosuppressants).

[0064] In this invention, the term "cytotoxic agent" refers to a substance that inhibits or blocks cellular function and / or causes cell death or destruction.

[0065] "Chemotherapy agents" include chemical compounds useful for treating immune system diseases.

[0066] The term "small molecule drug" refers to low molecular weight organic compounds that can modulate biological processes. A "small molecule" is defined as a molecule with a molecular weight of less than 10 kD, generally less than 2 kD, and preferably less than 1 kD. Small molecules include, but are not limited to, inorganic molecules, organic molecules, organic molecules containing inorganic components, molecules containing radioactive atoms, synthetic molecules, peptide mimetic compounds, and antibody mimetic compounds. As therapeutic agents, small molecules have higher cell permeability, are more susceptible to degradation, and are less likely to induce an immune response than large molecules.

[0067] As used herein, the term “immunomodulator” refers to a natural or synthetic active agent or drug that suppresses or modulates an immune response. The immune response may be a humoral or cellular response. Immunomodulators include immunosuppressants.

[0068] As used herein, "immunosuppressant," "immunosuppressant drug," or "immunosuppressant" refers to a therapeutic agent used to suppress or inhibit the activity of the immune system in immunosuppressive therapy.

[0069] The term "effective dose" refers to the amount or dose of the antibody, fragment, complex, composition, or combination of the present invention that, after being administered to a patient in one or more doses, produces the desired effect in a patient requiring treatment or prevention.

[0070] The "therapeutic dose" refers to the amount necessary to effectively achieve the desired therapeutic outcome at the required dose over the required period. The therapeutic dose is also the amount at which any toxicity or adverse effect of the antibody, antibody fragment, or complex or composition or combination does not extend to the beneficial effect of the therapy. For untreated subjects, the "therapeutic dose" preferably suppresses at least about 20% of a measurable parameter (e.g., tumor volume), more preferably at least about 40%, and even more preferably at least about 50%, 60%, or 70%.

[0071] The "preventive effective dose" refers to the amount of medication needed to effectively achieve the desired preventive outcome over the required period at the required dosage. Generally, the preventive dose is less than the therapeutic effective dose because preventive doses are applied before or during the early stages of the disease in the target population.

[0072] The terms “host cell,” “host cell line,” and “host cell culture” may be used interchangeably and refer to cells into which exogenous nucleic acids have been introduced, including their offspring. Host cells include “transformed organisms” and “transformed cells,” including primary transformed cells and their offspring regardless of passage number. Offspring may not be exactly the same as the parent cells in terms of nucleic acid content and may contain mutations. This specification includes mutant offspring with the same function or biological activity screened or selected from primary transformed cells.

[0073] As used herein, the term “labeling” refers to a compound or composition that is directly or indirectly compounded or fused with a reagent (e.g., a polynucleotide probe or antibody) and that facilitates detection by the reagent to which it is compounded or fused. Labeling can be detectable itself (e.g., radioisotope labeling or fluorescent labeling) or, when labeled by an enzyme catalyst, can catalytically alter the chemical properties of a detectable substrate compound or composition. The term is intended to include direct labeling of a probe or antibody by coupling (i.e., physical linking) a detectable substance to the probe or antibody, and indirect labeling of a probe or antibody by reaction with another directly labeled reagent.

[0074] "Individual" or "Subject" includes mammals. Mammals include, but are not limited to, livestock (e.g., cattle, goats, cats, dogs, horses), primates (e.g., humans, non-human primates such as monkeys), rabbits, and rodents (e.g., mice and rats). In some embodiments, the individual or subject is a human.

[0075] An "isolated" antibody is an antibody that has been isolated from the components of its natural environment in which it exists. In some embodiments, the antibody is purified to a purity of 95% or more than 99%, as determined, for example, by electrophoresis (e.g., SDS-PAGE, isoelectric focusing (IEF), capillary electrophoresis) or chromatography (e.g., ion exchange or reverse-phase HPLC).

[0076] "Isolated nucleic acids encoding an anti-CLDN18.2 antibody or a fragment thereof" refers to one or more nucleic acid molecules encoding the heavy chain or light chain (or a fragment thereof, e.g., a heavy chain variable region or a light chain variable region) of an antibody, and includes such nucleic acid molecules in a single vector or a divided vector, and such nucleic acid molecules at one or more locations in a host cell.

[0077] The sequence identity between sequences is calculated as follows.

[0078] To determine the percentage of identity between two amino acid sequences or two nucleic acid sequences, the sequences are aligned for optimal comparison (for example, gaps may be introduced in one or both of the first and second amino acid sequences or nucleic acid sequences for optimal alignment, or non-homologous sequences may be discarded for comparison). In one preferred embodiment, the length of the reference sequence to be aligned for comparison is at least 30%, preferably at least 40%, more preferably at least 50%, 60%, and even more preferably at least 70%, 80%, 90%, or 100% of the length of the reference sequence. Next, amino acid residues or nucleotides at the corresponding amino acid or nucleotide positions are compared. If a position in the first sequence is occupied by the same amino acid residue or nucleotide at the corresponding position in the second sequence, the molecules are identical at that position.

[0079] Mathematical algorithms can be used to perform sequence comparisons between two sequences and calculate the percentage of identity. In one preferred embodiment, the percentage of identity between two amino acid sequences is determined using the Needlema and Wunsch ((1970) J. Mol. Biol. 48:444-453) algorithm (available at http: / / www.gcg.com), which is integrated into the GAP program of the GCG software package, using a Blossum 62 matrix or a PAM250 matrix, and gap weights of 16, 14, 12, 10, 8, 6, or 4 and length weights of 1, 2, 3, 4, 5, or 6. In another preferred embodiment, the percentage of identity between two nucleotide sequences is determined using the NWSgapdna.CMP matrix, gap weights of 40, 50, 60, 70, or 80 and length weights of 1, 2, 3, 4, 5, or 6, which is integrated into the GAP program of the GCG software package (available at http: / / www.gcg.com). A particularly preferred parameter set (and one parameter set to be used unless otherwise specified) employs the Blossum 62 scoring matrix with a gap penalty of 12, a gap length penalty of 4, and a frameshift gap penalty of 5. Alternatively, the E. Meyers and W. Miller algorithm ((1989) CABIOS, 4:11-17), integrated into the ALIGN program (version 2.0), may be used to determine the identity percentage between two amino acid or nucleotide sequences using the PAM120 weighted remainder table, the gap length penalty of 12, and the gap penalty of 4. Additionally or selectively, the nucleic acid and protein sequences described herein can be used as "query sequences" to perform searches against public databases to identify, for example, sequences of other family members or related sequences.

[0080] As used herein, the term "hybridize under stringency conditions (e.g., low stringency, moderate stringency, high stringency, or very high stringency)" describes the conditions for hybridization and washing. Instructions for carrying out the hybridization reaction can be found in Current Protocols in Molecular Biology, John Wiley & Sons, NY (1989), 6.3.1–6.3.6, incorporated by reference. The reference describes both hydrated and unhydrated methods, and either method may be used. Preferred hybridization conditions as referred to herein include: 1) Low-stringency hybridization conditions, which involve washing twice in 6X sodium chloride / sodium citrate (SSC) at approximately 45°C, then in 0.2X SSC and 0.1% SDS at at least 50°C (in low-stringency conditions, the washing temperature can be increased to 55°C); and 2) Moderate-stringency hybridization conditions, which involve washing in 6X SSC at approximately 45°C, then in 0.2X SDS at 60°C. 3) High stringency hybridization conditions involve washing once or multiple times with SC and 0.1% SDS at approximately 45°C, followed by washing once or multiple times with 6X SSC, then 0.2X SSC and 0.1% SDS at 65°C, preferably, 4) extremely high stringency hybridization conditions involve washing once or multiple times with 0.5 M sodium phosphate and 7% SDS at 65°C, then 0.2X SSC and 0.1% SDS at 65°C. The extremely high stringency condition (4) is a preferred condition and should be used unless otherwise specified.

[0081] The term "antitumor effect" refers to a biological effect that can be expressed by various means, including, but is not limited to, a reduction in tumor volume, a reduction in the number of tumor cells, a reduction in tumor cell proliferation, or a reduction in tumor cell viability.

[0082] The terms “tumor” and “cancer” are used interchangeably herein and include solid tumors and humoral tumors.

[0083] The terms “cancer” and “cancerous” generally refer to or describe a physiological disorder in mammals characterized by unregulated cell growth. In one embodiment, cancers suitable for treatment with the antibodies of the present invention include gastric cancer or pancreatic cancer, and include metastatic forms of these cancers.

[0084] The term “tumor” includes all neoplastic cell growth and proliferation, whether malignant or benign, and all precancerous and cancerous cells and tissues. The terms “cancer,” “cancerous,” and “tumor” are not mutually exclusive when used herein.

[0085] The term "medicinal adjuvants" refers to diluents, adjuvants (e.g., Freund's adjuvants (complete or incomplete)), excipients, vectors, stabilizers, etc., that are administered together with the active substance.

[0086] The term "pharmaceutical composition" refers to a composition in which the active ingredient contained herein exists in a form that enables its biological activity, and which does not contain any other ingredient that is toxic to the subject to which the composition is administered.

[0087] The term "pharmaceutical combination" refers to a non-fixed combination product or a fixed combination product, including, but not limited to, drug kits and pharmaceutical compositions. The term "non-fixed combination" refers to a combination in which active ingredients (e.g., (i) an anti-CLDN18.2 antibody or a fragment thereof, and (ii) another therapeutic agent) are administered to a patient sequentially in separate entities simultaneously, without specific time constraints, or at the same or different time intervals, where such administration provides two or more active ingredients in the patient's body at levels that are prophylactically or therapeutically effective. In some embodiments, the anti-CLDN18.2 antibody or a fragment thereof and the other therapeutic agent used in the pharmaceutical combination are administered so as not to exceed the levels they would be at when used individually. The term "fixed combination" refers to a combination in which two or more active ingredients are administered to a patient simultaneously in the form of a single entity. Preferably, by selecting the doses and / or time intervals of two or more active ingredients, the combined use of each ingredient can achieve a better effect in treating a disease or condition than when any one ingredient is used alone. Each component may be in the form of a single formulation, and these formulations may be the same or different.

[0088] The term “combination therapy” refers to the treatment of a disease described herein by administering two or more therapeutic agents or forms of treatment (e.g., radiation therapy or surgery). Such administration includes co-administration of these therapeutic agents nearly simultaneously, for example, in a single capsule having a fixed proportion of the active ingredient. Alternatively, such administration includes co-administration of each active ingredient in multiple or separate containers (e.g., tablets, capsules, powders and liquids). Powders and / or liquids may be reconstituted or diluted to the desired dose before administration. Furthermore, such administration includes using each type of therapeutic agent sequentially at substantially the same time or at different times. In any case, the treatment program provides the beneficial effect of the combination of pharmaceuticals in the treatment of the disease or condition described herein.

[0089] As used herein, “treatment” means reducing, interrupting, delaying, relieving, stopping, decreasing, or reversing the progression or severity of any existing symptoms, symptoms, conditions, disease, or illness.

[0090] As used herein, “prevention” includes inhibiting the onset or progression of a disease, condition, or symptoms related to a particular disease or condition. In some embodiments, subjects with a family history of cancer are candidates for a prevention program. Generally, in the context of cancer, the term “prevention” refers to the administration of a drug before the onset of any signs or symptoms related to cancer, particularly before cancer develops in subjects at risk of developing cancer.

[0091] The term “vector,” as used herein, refers to a nucleic acid molecule capable of replicating another nucleic acid ligated to it. The term includes vectors as self-replicating nucleic acid structures, and vectors linked to the genome of a host cell into which they are introduced. Some vectors can guide the expression of a nucleic acid manipulably ligated to them. Such vectors are referred to herein as “expression vectors.”

[0092] "Subject / patient / individual sample" refers to a collection of cells or fluids obtained from a patient or subject. Tissue or cell samples may originate from solid tissues such as fresh, frozen, and / or preserved organs or tissue samples, biopsy samples, or puncture samples; blood or any blood component; body fluids such as cerebrospinal fluid, amniotic fluid, peritoneal fluid, or interstitial fluid; or cells derived from any stage of pregnancy or development in the subject. Tissue samples may contain compounds that do not naturally mix with tissues in nature, such as preservatives, anticoagulants, buffers, fixatives, nutrients, and antibiotics. II. Antibodies

[0093] In some embodiments, the anti-CLDN18.2 antibody or its antigen-binding fragment of the present invention binds to CLDN18.2 (e.g., human CLDN18.2) with high affinity. In some embodiments, the anti-CLDN18.2 antibody of the present invention specifically binds to CLDN18.2 (e.g., human CLDN18.2) but does not bind to CLDN18.1 (e.g., human CLDN18.1). In some embodiments, the antibody or its antigen-binding fragment of the present invention has a higher binding affinity to human CLDN18.2 than known CLDN18.2 antibodies, such as Zolbetuximab (abbreviated as Zmab) antibody. In some embodiments, the affinity of the antibody is measured by biolayer interferometry or surface plasmon resonance.

[0094] In some embodiments, the anti-CLDN18.2 antibody of the present invention has the following equilibrium dissociation constant (K D ) binds to human CLDN18.2, and the K D The K is less than approximately 15 nM, preferably about 10 nM, 9.5 nM, 9 nM, 8.5 nM, 8 nM, 7.5 nM, 7 nM, 6.5 nM, 6 nM, 5.5 nM, 5 nM, 4.5 nM, 4 nM, 3.5 nM, 3 nM or less, and in some embodiments, the K D It lies between the above values ​​(including the endpoints).

[0095] In some embodiments, the antibody or antigen-binding fragment of the present invention binds to CLDN18.2 on the cell surface. In some embodiments, the antibody or antigen-binding fragment of the present invention does not bind to CLDN18.1 on the cell surface. In some embodiments, CLDN18.2 is expressed or overexpressed on the cell surface. In some embodiments, the cells are CHO cells or 293 cells expressing CLDN18.2, for example, CHO-S cells or HEK293 cells. In some embodiments, the cells are cancer cells expressing CLDN18.2, for example, cells that naturally express CLDN18.2, or cells that express CLDN18.2 by artificial transfection, or cells having CLDN18.2 with increased expression levels by artificial transfection, for example, gastric cancer cells or pancreatic cancer cell lines expressing CLDN18.2, for example, NUGC-4, KATO III and DAN-G cell lines, for example, KATO III and DAN-G cell lines overexpressing CLDN18.2.

[0096] In some embodiments, the binding is detected by flow cytometry. In some embodiments, the antibodies of the present invention bind to CLDN18.2 overexpressed in CHO cells at EC50 of approximately 15 nM, 10 nM, 9 nM, 8 nM, 7 nM, 6 nM, and 5.5 nM or less. In some embodiments, the antibodies of the present invention bind to cancer cells expressing CLDN18.2 at EC50 of approximately 4 nM, 3.7 nM, 3.5 nM, 3 nM, 2.5 nM, 2 nM, 1.5 nM, 1 nM, 0.9 nM, 0.8 nM, 0.7 nM, and 0.6 nM or less, for example, gastric cancer cell lines or pancreatic cancer cell lines expressing CLDN18.2, for example, NUGC-4, KATO III, and DAN-G cell lines, for example, KATO III and DAN-G cell lines overexpressing CLDN18.2. In some embodiments, the EC50 of the antibody of the present invention when bound to cells expressing CLDN18.2 corresponds to or is smaller than the EC50 of a known antibody, such as Zmab, or is smaller than 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, or 15% of the EC50 of a known antibody, Zmab.

[0097] In some embodiments, the antibody or antigen-binding fragment of the present invention has ADCC activity or CDC activity, for example, ADCC activity or CDC activity equivalent to that of a known antibody (e.g., Zmab), or higher ADCC activity or CDC activity.

[0098] In some embodiments, the antibody or antigen-binding fragment of the present invention can suppress tumor cells, for example, tumor cells expressing CLDN18.2.

[0099] In some embodiments, the antibodies or antigen-binding fragments of the present invention can be used in the treatment of cancer. In some embodiments, the antibodies or antigen-binding fragments of the present invention can effectively suppress tumor growth, with tumor suppression rates of approximately 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70% or more.

[0100] In some embodiments, the anti-CLDN18.2 antibody of the present invention or its antigen-binding fragment comprises three complementarity-determining regions (HCDRs) from the heavy chain variable region: HCDR1, HCDR2, and HCDR3.

[0101] In some embodiments, the anti-CLDN18.2 antibody of the present invention or its antigen-binding fragment comprises three complementarity-determining regions (LCDRs) from the light chain variable region: LCDR1, LCDR2, and LCDR3.

[0102] In some embodiments, the anti-CLDN18.2 antibody or its antigen-binding fragment of the present invention comprises three complementarity-determining regions (HCDRs) from the heavy chain variable region and three complementarity-determining regions (LCDRs) from the light chain variable region.

[0103] In some embodiments, the anti-CLDN18.2 antibody of the present invention or its antigen-binding fragment comprises a heavy chain variable region (VH). In some embodiments, the anti-CLDN18.2 antibody of the present invention or its antigen-binding fragment comprises a light chain variable region (VL). In some embodiments, the anti-CLDN18.2 antibody of the present invention or its antigen-binding fragment comprises a heavy chain variable region (VH) and a light chain variable region (VL). In some embodiments, the heavy chain variable region comprises three complementarity-determining regions (CDRs) from the heavy chain variable region: HCDR1, HCDR2, and HCDR3. In some embodiments, the light chain variable region comprises three complementarity-determining regions (CDRs) from the light chain variable region: LCDR1, LCDR2, and LCDR3.

[0104] In some embodiments, the anti-CLDN18.2 antibody of the present invention or its antigen-binding fragment further comprises an antibody heavy chain constant region HC. In some embodiments, the anti-CLDN18.2 antibody of the present invention or its antigen-binding fragment further comprises an antibody light chain constant region LC. In some embodiments, the anti-CLDN18.2 antibody of the present invention or its antigen-binding fragment further comprises a heavy chain constant region HC and a light chain constant region LC.

[0105] In some embodiments, the heavy chain variable region of the present invention is (i) an amino acid sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with an amino acid sequence selected from SEQ ID NOs: 4, 15, 21, 26, 27, 36, 37, 45, 48, 53, 56, 61, 66, 72, 73, 80, or 85, or consisting of such an amino acid sequence, (ii) Consists of an amino acid sequence selected from sequence numbers 4, 15, 21, 26, 27, 36, 37, 45, 48, 53, 56, 61, 66, 72, 73, 80, or 85, or consists of the above amino acid sequence, (iii) An amino acid sequence having one or more (preferably 10 or fewer, more preferably 5 or fewer, 4 or fewer, 3 or fewer, 2 or fewer, 1 or fewer) amino acid mutations (preferably amino acid substitutions, more preferably amino acid conservative substitutions) compared to an amino acid sequence selected from SEQ ID NOs. 4, 15, 21, 26, 27, 36, 37, 45, 48, 53, 56, 61, 66, 72, 73, 80, or 85, or comprising such an amino acid sequence, preferably without such amino acid mutations occurring in the CDR region.

[0106] In some embodiments, the light chain variable region of the present invention is (i) an amino acid sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with an amino acid sequence selected from SEQ ID NOs. 9, 19, 22, 31, 32, 40, 41, 47, 49, 55, 57, 65, 68, 75, 76, 83, or 86, or consisting of such an amino acid sequence, (ii) an amino acid sequence selected from sequence numbers 9, 19, 22, 31, 32, 40, 41, 47, 49, 55, 57, 65, 68, 75, 76, 83 or 86, or consisting of the above amino acid sequence, (iii) An amino acid sequence having one or more (preferably 10 or fewer, more preferably 5 or fewer, 4 or fewer, 3 or fewer, 2 or fewer, 1 or fewer) amino acid mutations (preferably amino acid substitutions, more preferably amino acid conservative substitutions) compared to an amino acid sequence selected from SEQ ID NOs. 9, 19, 22, 31, 32, 40, 41, 47, 49, 55, 57, 65, 68, 75, 76, 83 or 86, or comprising such an amino acid sequence, preferably without such amino acid mutations occurring in the CDR region.

[0107] In some embodiments, the three complementarity-determining regions (HCDRs) from the heavy chain variable region of the present invention, HCDR1, HCDR2, and HCDR3, are (i) Three complementarity determination regions HCDR1, HCDR2 and HCDR3 included in VH as shown in Sequence ID No. 4, (ii) Three complementarity determination regions HCDR1, HCDR2 and HCDR3 included in VH as shown in Sequence ID No. 15 or 21, (iii) Three complementarity-determining regions HCDR1, HCDR2 and HCDR3 included in VH as shown in Sequence ID No. 26 or 27, (iv) Three complementarity-determining regions HCDR1, HCDR2 and HCDR3 included in VH as shown in Sequence ID No. 36 or 37, (v) Three complementarity determination regions HCDR1, HCDR2 and HCDR3 included in VH as shown in Sequence ID No. 45 or 48, (vi) Three complementarity determination regions HCDR1, HCDR2 and HCDR3 included in VH as shown in Sequence ID No. 53 or 56, (vii) Three complementarity determination regions HCDR1, HCDR2 and HCDR3 included in VH as shown in Sequence ID No. 61 or 66, (viii) Three complementarity determination regions HCDR1, HCDR2 and HCDR3 included in VH as shown in Sequence ID No. 72 or 73, (ix) Three complementarity determination regions HCDR1, HCDR2 and HCDR3 included in VH as shown in Sequence ID No. 80 or 85, or A sequence described in any one of (x)(i) to (ix) that contains at least one and a total of five, four, three, two, or one amino acid mutation (preferably an amino acid substitution, preferably a conservative substitution) in the three HCDR regions, Selected from.

[0108] In some embodiments, the three complementarity determination regions (LCDRs) LCDR1, LCDR2, and LCDR3 from the light chain variable region of the present invention are: (i) The three complementarity determination regions LCDR1, LCDR2 and LCDR3 included in the VL shown in Sequence ID No. 9, (ii) Three complementarity determination regions LCDR1, LCDR2 and LCDR3 included in the VL shown in Sequence ID No. 19 or 22, (iii) Three complementarity determination regions LCDR1, LCDR2 and LCDR3 included in the VL shown in Sequence ID No. 31 or 32, (iv) Three complementarity determination regions LCDR1, LCDR2 and LCDR3 included in the VL shown in Sequence ID No. 40 or 41, (v) Three complementarity determination regions LCDR1, LCDR2 and LCDR3 included in the VL shown in Sequence ID No. 47 or 49, (vi) Three complementarity determination regions LCDR1, LCDR2 and LCDR3 included in the VL shown in Sequence ID No. 55 or 57, (vii) Three complementarity determination regions LCDR1, LCDR2 and LCDR3 included in the VL shown in sequence number 65 or 68, (viii) Three complementarity determination regions LCDR1, LCDR2 and LCDR3 included in the VL shown in Sequence ID No. 75 or 76, (ix) Three complementarity determination regions LCDR1, LCDR2 and LCDR3 included in the VL shown in Sequence ID No. 83 or 86, or A sequence described in any one of (x)(i) to (ix) that contains at least one and a total of five, four, three, two, or one amino acid mutation (preferably an amino acid substitution, preferably a conservative substitution) in the three LCDR regions, Selected from.

[0109] In some embodiments, HCDR1 comprises or consists of the amino acid sequence of SEQ ID NOs: 1, 12, 23, 33, 42, 50, 58, 69, or 77, or HCDR1 comprises an amino acid sequence having one, two, or three modifications (preferably amino acid substitutions, preferably conservative substitutions) compared to the amino acid sequence of SEQ ID NOs: 1, 12, 23, 33, 42, 50, 58, 69, or 77.

[0110] In some embodiments, HCDR2 comprises or consists of the amino acid sequences of SEQ ID NOs: 2, 13, 20, 24, 34, 43, 51, 59, 70, 78, 84, 93, or 94, or HCDR2 comprises an amino acid sequence having one, two, or three modifications (preferably amino acid substitutions, preferably conservative substitutions) compared to the amino acid sequences of SEQ ID NOs: 2, 13, 20, 24, 34, 43, 51, 59, 70, 78, 84, 93, or 94, among which, Sequence ID 93 is YIAPFXGDSRYNQKFKG, where X is any amino acid, preferably N or Q or a conserved amino acid substitution, or Sequence ID 94 is VIWGDXSTNYHSVLIS, where X is any amino acid, preferably G or N or a conserved amino acid substitution.

[0111] In some embodiments, HCDR3 comprises or consists of the amino acid sequence of SEQ ID NOs: 3, 14, 25, 35, 44, 52, 60, 71, or 79, or HCDR3 comprises an amino acid sequence having one, two, or three modifications (preferably amino acid substitutions, preferably conservative substitutions) compared to the amino acid sequence of SEQ ID NOs: 3, 14, 25, 35, 44, 52, 60, 71, or 79.

[0112] In some embodiments, LCDR1 comprises or consists of the amino acid sequence of SEQ ID NOs: 6, 16, 28, 38, 62, 67, or 11, or LCDR1 comprises an amino acid sequence having one, two, or three modifications (preferably amino acid substitutions, preferably conservative substitutions) compared to the amino acid sequence of SEQ ID NOs: 6, 16, 28, 38, 62, 67, or 11. Here, sequence number 11 is KSSQSLLXGGNQKNYLT, where X is any amino acid, preferably N or Q or a conserved amino acid substitution.

[0113] In some embodiments, LCDR2 comprises or consists of the amino acid sequence of SEQ ID NOs: 7, 17, 29, 63, or 81, or LCDR2 comprises an amino acid sequence having one, two, or three modifications (preferably amino acid substitutions, preferably conservative substitutions) compared to the amino acid sequence of SEQ ID NOs: 7, 17, 29, 63, or 81.

[0114] In some embodiments, LCDR3 comprises or consists of the amino acid sequence of SEQ ID NOs. 8, 18, 30, 39, 46, 54, 64, 74, or 82, or LCDR3 comprises an amino acid sequence having one, two, or three modifications (preferably amino acid substitutions, preferably conservative substitutions) compared to the amino acid sequence of SEQ ID NOs. 8, 18, 30, 39, 46, 54, 64, 74, or 82.

[0115] In some embodiments, the antibody heavy chain constant region HC of the present invention is the heavy chain constant region of IgG1, IgG2, IgG3, or IgG4, preferably the heavy chain constant region of IgG1. In some embodiments, the antibody light chain constant region LC of the present invention is the lambda or kappa light chain constant region, preferably the kappa light chain constant region.

[0116] In some embodiments, the antibody heavy chain constant region HC of the present invention is (i) an amino acid sequence having at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with an amino acid sequence selected from SEQ ID NO: 5, or consisting of the above amino acid sequence. (ii) comprising an amino acid sequence selected from Sequence ID No. 5, or consisting of the said amino acid sequence, (iii) an amino acid sequence having one or more (preferably 20 or fewer or 10 or fewer, more preferably 5 or fewer, 4 or fewer, 3 or fewer, 2 or fewer, 1 or fewer) amino acid mutations (preferably amino acid substitutions, more preferably amino acid conservative substitutions) compared to the amino acid sequence selected from Sequence ID No. 5, or comprising the above amino acid sequence.

[0117] In some embodiments, the amino acid mutation occurs in the Fc region. In some embodiments, the amino acid mutation in the Fc region improves the CDC or ADCC activity of the antibody.

[0118] In some embodiments, the antibody light chain constant region LC of the present invention is (i) an amino acid sequence having at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with an amino acid sequence selected from SEQ ID NO: 10, or consisting of such an amino acid sequence. (ii) comprising an amino acid sequence selected from Sequence ID No. 10, or consisting of the said amino acid sequence, (iii) an amino acid sequence having one or more (preferably 20 or fewer or 10 or fewer, more preferably 5 or fewer, 4 or fewer, 3 or fewer, 2 or fewer, 1 or fewer) amino acid mutations (preferably amino acid substitutions, more preferably amino acid conservative substitutions) compared to an amino acid sequence selected from Sequence ID No. 10, or comprising the above amino acid sequence.

[0119] In some specific embodiments of the present invention, the anti-CLDN18.2 antibody or its antigen-binding fragment is (i) The three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in Sequence ID No. 4, and the three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in Sequence ID No. 9, (ii) Three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in SEQ ID NO: 15 or 21, and three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in SEQ ID NO: 19 or 22, (iii) Three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in SEQ ID NO: 26 or 27, and three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in SEQ ID NO: 31 or 32, (iv) Three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in SEQ ID NO: 36 or 37, and three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in SEQ ID NO: 40 or 41, (v) Three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in SEQ ID NO: 45 or 48, and three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in SEQ ID NO: 47 or 49, (vi) The three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in SEQ ID NO: 53 or 56, and the three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in SEQ ID NO: 55 or 57, (vii) The three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in SEQ ID NO: 61 or 66, and the three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in SEQ ID NO: 65 or 68, (viii) The three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in SEQ ID NO: 72 or 73, and the three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in SEQ ID NO: 75 or 76, (ix) Three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH as shown in SEQ ID NO: 80 or 85, and three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL as shown in SEQ ID NO: 83 or 86, Includes.

[0120] In some specific embodiments of the present invention, the anti-CLDN18.2 antibody or its antigen-binding fragment is (i) HCDR1, HCDR2, and HCDR3 shown in the amino acid sequences of SEQ ID NOs. 1, 2, and 3, respectively, and LCDR1, LCDR2, and LCDR3 shown in the amino acid sequences of SEQ ID NOs. 6, 7, and 8, respectively, (ii) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 12, 13, and 14 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 16, 17, and 18 respectively, (iii) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 12, 20, and 14 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 16, 17, and 18 respectively, (iv) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 12, 93, and 14 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 16, 17, and 18 respectively, (v) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 23, 24, and 25 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 28, 29, and 30 respectively, (vi) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 33, 34, and 35 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 38, 17, and 39 respectively, (vii) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 42, 43, and 44 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 38, 17, and 46 respectively, (viii) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 50, 51, and 52 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 28, 17, and 54 respectively, (ix) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 58, 59, and 60 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 62, 63, and 64 respectively, (x) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 58, 59, and 60 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 67, 63, and 64 respectively, (xi) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 58, 59, and 60 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 11, 63, and 64 respectively, (xii) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 69, 70, and 71 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 38, 17, and 74 respectively, (xiii) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 77, 78, and 79 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 28, 81, and 82 respectively, (xiv) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 77, 84, and 79 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 28, 81, and 82 respectively, (xv) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 77, 94, and 79 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 28, 81, and 82 respectively, Includes.

[0121] In some specific embodiments of the present invention, the anti-CLDN18.2 antibody or its antigen-binding fragment is (i) VH comprising the amino acid sequence shown in SEQ ID NO: 4 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 9 or an amino acid sequence having at least 90% identity thereto, (ii) VH comprising the amino acid sequence shown in SEQ ID NO: 15 or 21 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 19 or 22 or an amino acid sequence having at least 90% identity thereto, (iii) VH comprising the amino acid sequence shown in SEQ ID NO: 15 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 19 or an amino acid sequence having at least 90% identity thereto, (iv) VH comprising the amino acid sequence shown in SEQ ID NO: 21 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 22 or an amino acid sequence having at least 90% identity thereto, (v) VH comprising the amino acid sequence shown in SEQ ID NO: 26 or 27 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 31 or 32 or an amino acid sequence having at least 90% identity thereto, (vi) VH comprising the amino acid sequence shown in SEQ ID NO: 26 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 31 or an amino acid sequence having at least 90% identity thereto, (vii) VH comprising the amino acid sequence shown in SEQ ID NO: 27 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 32 or an amino acid sequence having at least 90% identity thereto, (viii) VH comprising the amino acid sequence shown in SEQ ID NO: 36 or 37 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 40 or 41 or an amino acid sequence having at least 90% identity thereto, (ix) VH comprising the amino acid sequence shown in SEQ ID NO: 36 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 40 or an amino acid sequence having at least 90% identity thereto, (x) VH containing the amino acid sequence shown in SEQ ID NO: 37 or an amino acid sequence having at least 90% identity thereto, or consisting of the said amino acid sequence, and VL containing the amino acid sequence shown in SEQ ID NO: 41 or an amino acid sequence having at least 90% identity thereto, (xi) VH comprising the amino acid sequence shown in SEQ ID NO: 45 or 48 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 47 or 49 or an amino acid sequence having at least 90% identity thereto, (xii) VH comprising the amino acid sequence shown in SEQ ID NO: 45 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 47 or an amino acid sequence having at least 90% identity thereto, (xiii) VH comprising the amino acid sequence shown in SEQ ID NO: 48 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 49 or an amino acid sequence having at least 90% identity thereto, (xiv) VH comprising the amino acid sequence shown in SEQ ID NO: 53 or 56 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 55 or 57 or an amino acid sequence having at least 90% identity thereto, (xv) VH, which includes the amino acid sequence shown in SEQ ID NO: 53 or an amino acid sequence having at least 90% identity thereto, or consisting of the amino acid sequence said, and VL, which includes the amino acid sequence shown in SEQ ID NO: 55 or an amino acid sequence having at least 90% identity thereto, (xvi) VH comprising the amino acid sequence shown in SEQ ID NO: 56 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 57 or an amino acid sequence having at least 90% identity thereto, (xvii) VH comprising the amino acid sequence shown in SEQ ID NO: 61 or 66 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 65 or 68 or an amino acid sequence having at least 90% identity thereto, (xviii) VH comprising the amino acid sequence shown in SEQ ID NO: 61 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 65 or an amino acid sequence having at least 90% identity thereto, (xix) VH comprising the amino acid sequence shown in SEQ ID NO: 66 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 68 or an amino acid sequence having at least 90% identity thereto, (xx) VH comprising the amino acid sequence shown in SEQ ID NO: 72 or 73 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 75 or 76 or an amino acid sequence having at least 90% identity thereto, (xxi) VH comprising the amino acid sequence shown in SEQ ID NO: 72 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 75 or an amino acid sequence having at least 90% identity thereto, (xxii) VH comprising the amino acid sequence shown in SEQ ID NO: 73 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 76 or an amino acid sequence having at least 90% identity thereto, (xxiii) VH comprising the amino acid sequence shown in SEQ ID NO: 80 or 85 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 83 or 86 or an amino acid sequence having at least 90% identity thereto, (xxiv) VH comprising the amino acid sequence shown in SEQ ID NO: 80 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 83 or an amino acid sequence having at least 90% identity thereto, (xxv) VH, which includes the amino acid sequence shown in SEQ ID NO: 85 or an amino acid sequence having at least 90% identity thereto, or consisting of the said amino acid sequence, and VL, which includes the amino acid sequence shown in SEQ ID NO: 86 or an amino acid sequence having at least 90% identity thereto, Includes.

[0122] In one embodiment of the present invention, the amino acid mutations described herein include amino acid substitutions, insertions, or deletions. Preferably, the amino acid mutations described herein are amino acid substitutions, and preferably conservative substitutions.

[0123] In a preferred embodiment, the amino acid mutation described in the present invention occurs in a region outside the CDR (e.g., FR). More preferably, the amino acid mutation described in the present invention occurs in a region outside the heavy chain variable region and / or the light chain variable region. In some embodiments, the amino acid mutation described in the present invention occurs in the Fc region of the antibody heavy chain constant region, and in a preferred embodiment, the amino acid mutation in the Fc region improves the ADCC and / or CDC activity of the antibody.

[0124] In some embodiments, the substitutions are conservative substitutions. A conservative substitution refers to the substitution of one amino acid with another amino acid of the same type, for example, one acidic amino acid being substituted with another acidic amino acid, one basic amino acid being substituted with another basic amino acid, or one neutral amino acid being substituted with another neutral amino acid. Exemplary substitutions are shown in the table below.

[0125] [Table 2]

[0126] In one embodiment, the substitution occurs in the CDR region of the antibody. Generally, the resulting mutant has modifications (e.g., improvements) to certain biological properties (e.g., enhanced affinity) compared to the parent antibody, and / or retains some substantially preserved biological properties of the parent antibody. An exemplary substitution mutant is an affinity-mature antibody.

[0127] In one embodiment, the antibodies provided herein are modified to increase or decrease the degree of glycosylation of the antibody. Addition or deletion of glycosylation sites in an antibody can be easily achieved by modifying the amino acid sequence so that one or more glycosylation sites are produced or removed. If the antibody contains an Fc region, the sugars attached to it can be modified. In some applications, modifications to remove unwanted glycosylation sites may be useful; for example, removing a fucose motif can improve antibody-dependent cytotoxicity (ADCC) function (see Shield et al. (2002) JBC277:26733). In other applications, galactosidation modification can modify complement-dependent cytotoxicity (CDC).

[0128] In one embodiment, Fc region variants can be produced by introducing one or more amino acid modifications to the Fc region of an antibody provided herein, thereby altering one or more functional properties of the antibody, such as serum half-life, complement binding, complement-dependent cytotoxicity, Fc receptor binding, and / or antibody-dependent cytotoxicity. The Fc region variants may include human Fc region sequences (e.g., human IgG1, IgG2, IgG3, or IgG4 Fc regions) that contain amino acid mutations (e.g., substitutions) at one or more amino acid positions.

[0129] In one embodiment of the present invention, the antibody described herein improves the ADCC activity or CDC activity of the antibody by introducing a modification in the Fc region.

[0130] In one embodiment, it may be necessary to produce antibodies modified by cysteine ​​engineering, for example, "thioMAb" in which one or more residues of the antibody are replaced with cysteine ​​residues.

[0131] In some embodiments, the antibodies provided herein can be further modified to include other known and readily available non-protein moieties in the art. Moieties suitable for the inducing action of the antibody include, but are not limited to, water-soluble polymers. Non-limiting examples of water-soluble polymers include polyethylene glycol (PEG), ethylene glycol / propylene glycol copolymers, carboxymethylcellulose, dextran, polyvinyl alcohol, polyvinylpyrrolidone, poly-1,3-dioxane, poly-1,3,6-trioxane, ethylene / maleic anhydride copolymers, polyamino acids (homopolymers or random copolymers), and dextran or poly(n-vinylpyrrolidone) polyethylene glycol, propylene glycol homopolymers, polypropylene oxide / ethylene oxide copolymers, polyoxyethylated polyols (e.g., glycerin), polyvinyl alcohol, and mixtures thereof.

[0132] In some embodiments, the anti-CLDN18.2 antibody or its antigen-binding fragment of the present invention is (i) The antibody of the present invention exhibits similar or comparable binding affinity and / or specificity to CLDN18.2, (ii) Suppress the binding of the antibody of the present invention to CLDN18.2 (e.g., competitive suppression), (iii) Conjugating an epitope similar to or overlapping with the antibody of the present invention, (iv) Competitively binds to CLDN18.2 with the antibody of the present invention, (v) Having one or more biological properties of the antibody of the present invention It possesses one or more of the following characteristics.

[0133] In some embodiments, the anti-CLDN18.2 antibody of the present invention is an antibody in the IgG1 form, an antibody in the IgG2 form, an antibody in the IgG3 form, or an antibody in the IgG4 form, and is preferably an antibody in the IgG1 form.

[0134] In some embodiments, the anti-CLDN18.2 antibody is a monoclonal antibody.

[0135] In some embodiments, the anti-CLDN18.2 antibody is humanized.

[0136] In some embodiments, the anti-CLDN18.2 antibody is a human antibody.

[0137] In some embodiments, the anti-CLDN18.2 antibody is a chimeric antibody.

[0138] In some embodiments, the frame sequences of at least some anti-CLDN18.2 antibodies are human-shared frame sequences.

[0139] In one embodiment, the anti-CLDN18.2 antibody of the present invention further comprises an antibody fragment (e.g., an antigen-binding fragment), preferably selected from antibody fragments such as Fab, Fab', Fab'-SH, Fv, a single-chain antibody (e.g., scFv), (Fab')2, a single-domain antibody (e.g., VHH), dAb (domain antibody), or a linear antibody. III. Nucleic acids of the present invention and host cells containing them

[0140] In one embodiment, the present invention provides a nucleic acid encoding any of the above-described anti-CLDN18.2 antibodies or fragments thereof. In one embodiment, a vector comprising the nucleic acid is provided. In one embodiment, the vector is an expression vector, for example, pcDNA3.1. In one embodiment, a host cell comprising the nucleic acid or the vector is provided. In one embodiment, the host cell is eukaryotic. In another embodiment, the host cell is selected from yeast cells, mammalian cells (e.g., CHO cells (e.g., CHO-S) or 293 cells (e.g., 293F or HEK293 cells)), or other cells to which the preparation of the antibody or fragment thereof is applied. In another embodiment, the host cell is prokaryotic.

[0141] In one embodiment, the present invention provides a nucleic acid encoding any anti-CLDN18.2 antibody or a fragment thereof as described herein. The nucleic acid may include a nucleic acid encoding the amino acid sequence of the light chain variable region and / or heavy chain variable region of the antibody, or a nucleic acid encoding the amino acid sequence of the light chain and / or heavy chain of the antibody.

[0142] For example, the nucleic acid of the present invention is a nucleic acid encoding an amino acid sequence shown in any one selected from SEQ ID NOs: 4, 15, 21, 26, 27, 36, 37, 45, 48, 53, 56, 61, 66, 72, 73, 80 or 85, or SEQ ID NOs: 9, 19, 22, 31, 32, 40, 41, 47, 49, 55, 57, 65, 68, 75, 76, 83 or 86, or SEQ ID NOs: 4, 15, 21, 26, 27, 36, 37, 45 The nucleic acid comprises an amino acid sequence having at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with the amino acid sequence shown in 48, 53, 56, 61, 66, 72, 73, 80, or 85, or any one selected from sequence numbers 9, 19, 22, 31, 32, 40, 41, 47, 49, 55, 57, 65, 68, 75, 76, 83, or 86.

[0143] The present invention further comprises nucleic acids hybridized with the following nucleic acids under stringency conditions, or nucleic acids having one or more substitutions (e.g., conservative substitutions), deletions, or insertions in the following nucleic acids: encoding the amino acid sequence shown in SEQ ID NOs: 4, 15, 21, 26, 27, 36, 37, 45, 48, 53, 56, 61, 66, 72, 73, 80, or 85, or any one selected from SEQ ID NOs: 9, 19, 22, 31, 32, 40, 41, 47, 49, 55, 57, 65, 68, 75, 76, 83, or 86. A nucleic acid containing a nucleic acid sequence, or a nucleic acid sequence encoding an amino acid sequence that has at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with the amino acid sequence shown in any one selected from SEQ ID NOs: 4, 15, 21, 26, 27, 36, 37, 45, 48, 53, 56, 61, 66, 72, 73, 80, or 85, or SEQ ID NOs: 9, 19, 22, 31, 32, 40, 41, 47, 49, 55, 57, 65, 68, 75, 76, 83, or 86.

[0144] In one embodiment, one or more vectors comprising the nucleic acid are provided. In one embodiment, the vector is an expression vector, for example, a eukaryotic expression vector. The vector includes, but is not limited to, a virus, plasmid, cosmid, lambda phage, or yeast artificial chromosome (YAC). In one embodiment, the vector is pcDNA3.1.

[0145] In one embodiment, a host cell containing the vector is provided. Suitable host cells for cloning or expressing an antibody-encoding vector include prokaryotic or eukaryotic cells as described herein. For example, the antibody can be produced in bacteria, particularly when glycosylation and Fc effector function are not required. After expression, the antibody can be isolated from a paste-like substance of bacterial cells in the soluble fraction and further purified.

[0146] In one embodiment, the host cell is eukaryotic. In another embodiment, the host cell is selected from yeast cells, mammalian cells, or other cells applied to the preparation of antibodies or fragments thereof. For example, eukaryotic microorganisms such as filamentous fungi and yeasts are suitable cloning or expression hosts for antibody-encoding vectors. For example, fungal and yeast strains whose glycosylation pathways have already been "humanized" produce antibodies having a partially or completely human glycosylated form. Host cells suitable for the expression of glycosylated antibodies can also be derived from multicellular organisms (invertebrates, vertebrates). Vertebrate cells may be used as hosts. For example, mammalian cell lines modified to be suitable for suspension growth can be used. Other examples of useful mammalian host cell lines include the monkey kidney CV1 cell line (COS-7) converted with SV40, and human embryonic kidney cell lines (HEK293, 293F, or 293T). Other useful mammalian host cell lines include Chinese hamster ovary (CHO) cells, DHFR-CHO cells, CHO-S cells, ExpiCHO, and myeloma cell lines such as Y0, NS0, and Sp2 / 0. In this field, mammalian host cell lines suitable for antibody production are known. IV. Production and Purification of Antibody Molecules of the Present Invention

[0147] In one embodiment, the present invention provides a method for preparing an antibody molecule or a fragment thereof (preferably an antigen-binding fragment) of the present invention, the method comprising culturing host cells under conditions suitable for the expression of nucleic acids encoding the antibody molecule or a fragment thereof (preferably an antigen-binding fragment) of the present invention, and optionally isolating the antibody or a fragment thereof (preferably an antigen-binding fragment). In one embodiment, the method further comprises recovering the antibody molecule or a fragment thereof (preferably an antigen-binding fragment) of the present invention from host cells.

[0148] In one embodiment, a method for preparing an antibody molecule of the present invention is provided, which, as described above, includes culturing host cells containing a nucleic acid encoding the antibody (e.g., one polypeptide chain and / or multiple polypeptide chains) or an expression vector of the nucleic acid under conditions suitable for antibody expression, and optionally recovering the antibody from the host cells (or host cell culture medium).

[0149] To produce the antibody molecule of the present invention by recombination, nucleic acids encoding the antibody (e.g., the antibody described above, e.g., one polypeptide chain and / or multiple polypeptide chains) are isolated, inserted into one or more vectors, and used for further cloning and / or expression in host cells. Such nucleic acids are readily isolated and sequenced by conventional processes (e.g., by using oligonucleotide probes that specifically bind to the genes encoding the heavy and light chains of the antibody).

[0150] Antibody molecules prepared as described herein can be purified by known prior art techniques such as high-performance liquid chromatography, ion exchange chromatography, gel electrophoresis, affinity chromatography, and size exclusion chromatography. The actual conditions for purifying specific proteins also depend on factors such as net charge, hydrophobicity, and hydrophilicity, which are obvious to those skilled in the art. The purity of the antibody molecules of the present invention can be determined by any one of a variety of well-known analytical methods, including size exclusion chromatography, gel electrophoresis, and high-performance liquid chromatography. V.Measurement method

[0151] Various known assay methods in this art can be used to identify, screen, or express the physical / chemical properties and / or biological activity of the anti-CLDN18.2 antibodies provided herein. In one embodiment, the antigen-binding activity of the antibodies of the present invention is tested by known methods such as ELISA and Western blotting. Binding to CLDN18.2 can be measured by known methods in this art, and exemplary methods are disclosed herein. In some embodiments, it is measured by radioimmunoassay (RIA), biolayer interferometry, MSD assay, surface plasmon resonance (SPR), or flow cytometry.

[0152] On the other hand, competitive assays can identify antibodies that competitively bind to CLDN18.2 with any of the anti-CLDN18.2 antibodies disclosed herein. In some embodiments, such competitive antibodies bind to epitopes (e.g., linear or conformational epitopes) that are similar to or overlap with the epitopes to which any of the anti-CLDN18.2 antibodies disclosed herein bind.

[0153] The present invention further provides a method for identifying biologically active anti-CLDN18.2 antibodies. Biological activity may include, for example, binding to CLDN18.2 (e.g., human CLDN18.2), binding to cells expressing CLDN18.2, activation of CDC or ADCC in cells, or suppressive activity against tumor cells. The present invention further provides antibodies having such biological activity in vivo and / or in vitro.

[0154] In one embodiment, this biological activity is tested against the antibody of the present invention.

[0155] The cells used in any of the in vitro assay methods described above include cell lines that naturally express CLDN18.2, or that express or overexpress CLDN18.2 through modification. Such cells further include DNA-transfected cell lines expressing CLDN18.2 and those expressing CLDN18.2 in atypical conditions. In some embodiments, such cells are gastric cancer cells or pancreatic cancer cells. In some embodiments, these cells are CHO cells expressing CLDN18.2. In some embodiments, these cells are NUGC-4, KATO III, and DAN-G cell lines, for example, KATO III and DAN-G cell lines overexpressing CLDN18.2.

[0156] Furthermore, any of the above-mentioned measurement methods can be performed by replacing or supplementing the anti-CLDN18.2 antibody with the immune complex of the present invention.

[0157] Furthermore, any of the above measurement methods can be performed using a combination of the anti-CLDN18.2 antibody and another activator. VI. Immune complexes

[0158] In some embodiments, the present invention provides an immune complex comprising any anti-CLDN18.2 antibody provided herein and a therapeutic agent comprising other substances, such as chemotherapeutic agents, cytokines, cytotoxic agents, other antibodies, small molecule drugs, and immunomodulators (e.g., anti-inflammatory agents or immunosuppressants). In one embodiment, the other substance is a cytotoxic agent, such as any agent that is toxic to cells.

[0159] In some embodiments, the immune complex is used for the prevention and treatment of cancer. VII. Pharmaceutical Compositions and Pharmaceutical Preparations

[0160] In some embodiments, the present invention provides compositions comprising any anti-CLDN18.2 antibody or a fragment thereof (preferably an antigen-binding fragment thereof) or an immune complex thereof as described herein, preferably the composition being a pharmaceutical composition. In one embodiment, the composition further comprises a medicinal adjuvant. In one embodiment, the composition, for example, a pharmaceutical composition, comprises a combination of the anti-CLDN18.2 antibody or a fragment thereof or an immune complex thereof of the present invention and one or more other therapeutic agents.

[0161] The present invention further comprises compositions (including pharmaceutical compositions or pharmaceutical formulations) comprising an anti-CLDN18.2 antibody or its immune complex, or compositions (including pharmaceutical compositions or pharmaceutical formulations) comprising a polynucleotide encoding an anti-CLDN18.2 antibody. In some embodiments, the composition comprises one or more antibodies or fragments thereof that conjugate to CLDN18.2, or one or more polynucleotides encoding one or more anti-CLDN18.2 antibodies or fragments thereof. These compositions may also comprise appropriate pharmacopoeias, such as pharmacopoeias known in the art, and pharmacopoeias comprising buffers.

[0162] As used herein, “medicinal vector” includes any or all of the following: a physiologically compatible solvent, dispersion medium, isotonic agent, absorption retarder, etc.

[0163] For information on the use of medicinal excipients and their applications, see also the Handbook of Pharmaceutical Excipients, 8th edition, RCRowe, PJSeskey, and SCOwen, Pharmaceutical Press, London, Chicago.

[0164] The compositions of the present invention can exist in various forms. These forms include, for example, liquid, semi-solid, and solid dosage forms, such as liquid solutions (e.g., solutions for injection and solutions for infusion), dispersants or suspensions, liposomes, and suppositories. The preferred form is determined by the desired mode of administration and therapeutic use.

[0165] A pharmaceutical formulation of the antibody described herein can be prepared by mixing the antibody of the present invention having a desired purity with one or more types of any medicinal auxiliary materials, preferably in the form of a lyophilized formulation or an aqueous solution.

[0166] The pharmaceutical composition or formulation of the present invention may further contain one or more active ingredients, the active ingredients being necessary for the specific indication being treated, and preferably having complementary activities that do not adversely affect each other. For example, it is desirable to further provide other therapeutic agents such as chemotherapeutic agents, cytokines, cytotoxic agents, vaccines, other antibodies, small molecule drugs, or immunomodulators. The active ingredients are present in appropriate combinations in amounts effective for the intended use.

[0167] It can be prepared as a sustained-release formulation. A suitable example of a sustained-release formulation is one comprising a semipermeable matrix of a hydrophobic solid polymer containing the antibody, wherein the matrix has a fixed form, such as a film or microcapsules. VIII. Drug combinations and drug kits

[0168] In some embodiments, the present invention further provides a pharmaceutical combination or pharmaceutical combination product comprising the anti-CLDN18.2 antibody or a fragment thereof (preferably an antigen-binding fragment), or an immune complex thereof, and one or more other therapeutic agents (e.g., chemotherapeutic agents, cytokines, cytotoxic agents, other antibodies, small molecule drugs, or immunomodulators).

[0169] Another object of the present invention is to provide a drug kit comprising the pharmaceutical combination of the present invention, preferably in the form of pharmaceutical dose units. This allows for the provision of dose units by administration program or pharmaceutical administration interval.

[0170] In one embodiment, the drug kit of the present invention is in the same package, - A first container containing a pharmaceutical composition comprising an anti-CLDN18.2 antibody or a fragment thereof, - A second container containing a pharmaceutical composition including other therapeutic agents, Includes. IX. Usage and Instructions

[0171] One aspect of the present invention provides a method for preventing or treating a tumor (e.g., cancer) in a subject, comprising administering to the subject an effective amount of the anti-CLDN18.2 antibody or a fragment thereof (preferably an antigen-binding fragment), an immune complex, a pharmaceutical composition, a pharmaceutical combination, or a drug kit of the present invention.

[0172] In some embodiments, the tumor (e.g., cancer) patient has CLDN18.2 (e.g., elevated levels of nucleic acids or proteins).

[0173] In some embodiments, the tumor, for example, cancer, includes solid tumors, hematological malignancies, and metastatic lesions. In one embodiment, an example of a solid tumor includes a malignant tumor. Cancer may be early, intermediate, or late-stage cancer or metastatic cancer.

[0174] In some embodiments, the treatment of the tumor benefits from CLDN18.2 with suppressed nucleic acid or protein levels. In some embodiments, the treatment of the tumor benefits from ADCC or CDC action by the antibody of the present invention.

[0175] In one embodiment, the anti-CLDN18.2 antibody of the present invention can suppress the proliferation of tumor cells, for example, tumor cells expressing CLDN18.2, such as gastric cancer cells and pancreatic cancer cells.

[0176] In one specific embodiment, the anti-CLDN18.2 antibody of the present invention has strong ADCC or CDC activity.

[0177] In some embodiments, the tumor is immune evasion of the tumor.

[0178] In some embodiments, the tumor is a cancer such as stomach cancer or pancreatic cancer.

[0179] The subjects may be mammals such as primates, preferably higher primates, such as humans (e.g., individuals suffering from or at risk of suffering from one of the diseases described herein). In one embodiment, the subject has or is at risk of suffering from one of the diseases described herein (e.g., cancer). In one embodiment, the subject is receiving or has already received other treatments such as chemotherapy and / or radiation therapy. In some embodiments, the subject has previously received or is receiving immunotherapy.

[0180] In other embodiments, the present invention provides the use of an antibody molecule or a fragment thereof or an immune complex thereof, or a pharmaceutical composition or a pharmaceutical combination or drug kit in the manufacture or preparation of a pharmaceutical, said pharmaceutical, which is used for the uses described herein, for example, for the prevention or treatment of the related diseases or conditions as described herein.

[0181] In some embodiments, the antibody molecule or fragment thereof or its immune complex, or pharmaceutical composition or pharmaceutical combination or drug kit of the present invention delays the onset of disease symptoms and / or symptoms associated with the disease.

[0182] In some embodiments, the antibody molecule or fragment thereof or its immune complex or pharmaceutical composition of the present invention may be administered in combination with one or more other therapies, such as therapeutic schemes and / or other therapeutic agents, and used for the purposes described herein, for example, for the prevention or treatment of the related diseases or conditions as described herein.

[0183] In some embodiments, the treatment method includes surgical procedures, radiation therapy, localized or intensive irradiation, etc.

[0184] In some embodiments, the therapeutic agent is selected from chemotherapeutic agents, cytokines, cytotoxic agents, vaccines, other antibodies, small molecule drugs, or immunomodulators.

[0185] Examples of immunomodulators include immunosuppressants or anti-inflammatory agents.

[0186] In some embodiments, the antibody combinations described herein can be administered individually, for example, as separate antibodies.

[0187] Such combinations of therapies include concomitant administration (for example, two or more therapeutic agents contained in the same or separate formulations) and individual administration, in the latter case, administration of the antibody of the present invention may be performed before, simultaneously with, and / or after the administration of other therapeutic agents and / or drugs.

[0188] The administration route of the pharmaceutical composition may be by known methods, such as oral, intravenous injection, intraperitoneal, intracerebral (intraparenchymal), intraventricular, intramuscular, intraocular, intraarterial, intraportal, or intrafocal routes, by a continuous release system, or by an implantable device. In some embodiments, the composition may be administered by bolus injection, continuous infusion, or by an implantable device.

[0189] The composition may be administered topically via an implantable membrane, sponge, or another suitable material that absorbs or encapsulates the desired molecule. In one embodiment, if an implantable device is used, the device can be implanted in any suitable tissue or organ and can deliver the desired molecule by diffusion, sustained-release bolus, or continuous administration. X. Methods and compositions for diagnosis and detection

[0190] In some embodiments, any anti-CLDN18.2 antibody or fragment thereof (preferably an antigen-binding fragment) provided herein can be used to detect the presence of CLDN18.2 in a biological sample. The term “detection” as used herein includes quantitative or qualitative detection, and exemplary detection methods include immunohistochemistry, immunocytochemistry, flow cytometry (e.g., FACS), antibody molecule-compound magnetic beads, ELISA assays, and PCR techniques (e.g., RT-PCR). In some embodiments, the biological sample is blood, serum, or other liquid sample derived from an organism. In some embodiments, the biological sample comprises cells or tissue. In some embodiments, the biological sample is derived from a lesion associated with an overgrowth or cancerous lesion.

[0191] In one embodiment, an anti-CLDN18.2 antibody or fragment thereof is provided for use in a diagnostic or detection method. In another embodiment, a method for detecting the presence of CLDN18.2 in a biological sample is provided. In one embodiment, the method comprises detecting the presence of the CLDN18.2 protein in a biological sample. In one embodiment, CLDN18.2 is human CLDN18.2. In one embodiment, the method comprises contacting a biological sample with the anti-CLDN18.2 antibody or fragment thereof described herein under conditions that allow binding of the anti-CLDN18.2 antibody or fragment thereof to CLDN18.2, and detecting whether a complex has been formed between the anti-CLDN18.2 antibody or fragment thereof and CLDN18.2. If a complex is formed, the presence of CLDN18.2 is indicated. The method may be performed in vitro or in vivo. In one embodiment, the anti-CLDN18.2 antibody or fragment thereof is used for selecting subjects suitable for treatment with the anti-CLDN18.2 antibody or fragment thereof, for example, CLDN18.2 therein is a biomarker for selecting said subjects.

[0192] In one embodiment, the antibody of the present invention can be used to diagnose tumors such as cancer and to evaluate (e.g., monitor) the treatment, progression, diagnosis, and / or staging of the diseases described herein in an individual. In one embodiment, a labeled anti-CLDN18.2 antibody or a fragment thereof is provided. The labeling includes, but is not limited to, directly detectable labels or portions (e.g., fluorescent labels, chromophore labels, high electron density labels, chemiluminescent labels, and radioactive labels) and portions indirectly detectable by, for example, enzyme-catalyzed reactions or intermolecular interactions, such as enzymes or ligands.

[0193] In some embodiments provided herein, the sample is obtained before treatment with an anti-CLDN18.2 antibody or a fragment thereof. In some embodiments, the sample is obtained before using other therapies. In some embodiments, the sample is obtained during or after treatment with other therapies.

[0194] In some embodiments, the specimen is formalin-fixed and paraffin-embedded (FFPE). In some embodiments, the specimen is a biopsy (e.g., core biopsy) specimen, a surgical specimen (e.g., a specimen obtained by surgical excision), or a fine needle aspiration.

[0195] In some embodiments, CLDN18.2 is detected before treatment, for example, before the start of treatment or before a treatment interval.

[0196] In some embodiments, the present invention provides a method for treating a disease, the method comprising determining the value of CLDN18.2 to test for the presence of CLDN18.2 in a subject (e.g., a sample) (e.g., a subject sample), comparing the value of CLDN18.2 to a control value, and if the value of CLDN18.2 is greater than the control value, treating the disease by administering to the subject a therapeutically effective amount of an anti-CLDN18.2 antibody or fragment thereof (e.g., an anti-CLDN18.2 antibody or fragment thereof as described herein) in combination, optionally with one or more other therapies.

[0197] Other aspects and embodiments of the present invention described above are illustrated in the drawings (followed by a brief description of the drawings) and the following detailed description of the invention, and are illustrated in the following examples. Any or all of the features described above and throughout this application can be combined in each embodiment of the present invention. The present invention will be further illustrated by the following examples, which are described by description and not limiting, and those skilled in the art should understand that various modifications can be made. Examples

[0198] [Table 3] Example 1: Construction of a stable expression cell line

[0199] Preparation of a human CLDN18.2 overexpressing cell line Following the manufacturer's instructions, cell lines stably expressing human Claudin18.2 (abbreviated as CLDN18.2, hereafter the same) were constructed using the Freedom® CHO-S® reagent kit (Invitrogen, A1369601). First, the full-length gene of human CLDN18.2 (UniProt ID: P56856-2) was constructed in the vector pCHO1.0. The constructed plasmids were then introduced into CHO-S cells (Invitrogen, A1369601) and HEK293 cells (Invitrogen, A14527) using chemical transfection and electrical transfection methods, respectively. The transfected cells underwent two rounds of press screening to obtain cell pools expressing CLDN18.2. Next, cells highly expressing CLDN18.2 were sorted by flow cytometry (MoFlo XDP, Beckman Coulter), and monoclonal cell lines CHO-hCLDN18.2 and HEK293-hCLDN18.2, which stably express CLDN18.2, were obtained by dilution.

[0200] Preparation of a human CLDN18.1 overexpressing cell line Following the manufacturer's instructions, we constructed a cell line that stably expresses human Claudin 18.1 (referred to as CLDN18.1; the same applies hereafter) using the Freedom® CHO-S® reagent kit (Invitrogen, A1369601). First, the full-length gene of human CLDN18.1 (UniProt ID: P56856-1) was constructed in the vector pCHO1.0 (Invitrogen, A1369601). The plasmid constructed by chemical transfection was introduced into CHO-S cells (Invitrogen, A1369601), and the transfected cells underwent two press screenings to obtain cell pools expressing CLDN18.1. Next, cells highly expressing CLDN18.1 were sorted by flow cytometry (MoFlo XDP, Beckman Coulter), and a monoclonal cell line CHO-hCLDN18.1 stably expressing CLDN18.1 was obtained by dilution.

[0201] Construction of tumor cell lines overexpressing CLDN18.2 The full-length human CLDN18.2 (UniProt ID: P56856-2) gene was constructed in the vector pWPT-GFP (Addgene, 12255), the GFP sequence was replaced, and HEK293T (ATCC, CRL-3216) cells were transfected with the lentiviral packaging vectors psPAX2 (Addgene, 12260) and pMD2.G (Addgene, 12259) to package the virus. Culture supernatants were collected after 48 and 72 hours, and lentiviral enrichment was performed using PEG8000. Pancreatic cancer DAN-G cells and gastric cancer KATO III cells were transfected with concentrated virus. Then, cells expressing CLDN18.2 were sorted by flow cytometry (MoFlo XDP, Beckman Coulter) to obtain tumor cell lines DAN-G-CLDN18.2 and KATO III-CLDN18.2, which were stably transfected with CLDN18.2. Example 2: Screening of monoclonal antibodies against hCLDN18.2 using hybridomas.

[0202] This invention employs hybridoma technology to immunize mice with cells (CHO-huClaudin18.2) obtained in Example 1 (see Table 1 for method and process), then obtain mouse splenocytes and fuse them with myeloma cells to obtain hybridoma cells capable of secreting antibodies against CLDN18.2. Mouse immunity

[0203] [Table 4] Hybridoma Fusion

[0204] Mars was killed, the spleen was removed by aseptic laparotomy, and the surrounding connective tissue was removed. Splenocytes were thoroughly released by pinhead extrusion to prepare a splenocyte suspension. The cell suspension was filtered through a 70 μm cell strainer, washed once with RPMI-1640 medium, and centrifuged at 1200 rpm for 6 minutes. After discarding the supernatant, the cells were resuspended in RBC lysis buffer (GIBCO), the erythrocytes were lysed, the supernatant was centrifuged and discarded, and the cells were resuspended in RPMI-1640 medium and counted. SP2 / 0 and erythrocyte-lysed splenocytes were mixed in a ratio of 1:2 to 1:1 and centrifuged at 1000 rpm for 6 minutes. After discarding the supernatant, the mixed cells were resuspended in fusion buffer. Furthermore, 15 ml of fusion buffer was added, and the cells were centrifuged at 1000 rpm for 5 minutes, discarding the supernatant. After repeating the above process once, an appropriate volume of fusion buffer was added and the cells were resuspended, and the density of the mixed cells was set to 1 × 10⁶. 7 The cells were adjusted to the desired concentration of cells / ml. After fusing in an electrofusion apparatus, the cells were allowed to stand in an electrofusion dish at room temperature for 5 minutes. The cells were then transferred to a centrifuge tube and 1-2 × 10⁶ cells were placed in the tube. 4The cells were diluted to individual cells / ml. 100 μl of the cell suspension was added to each well of a 96-well plate. After 5 days of fusion, the medium was changed. After culturing for 10 days (or longer, depending on the cell growth state), the supernatant was collected and detected by flow cytometry (FACS) to screen for positive clones. High-throughput screening using hybridoma cells

[0205] Hybridoma cells specifically expressing anti-CLDN18.2 antibodies were screened by flow cytometry (FACS), and the secreted antibodies did not bind to CLDN18.1.

[0206] The cells to be detected (HEK293-hCLDN18.2) obtained in Example 1 were counted, and 1 × 10⁻⁶ 6 The cells were diluted to individual cells / ml and added to a 96-well plate with a U-shaped bottom at a rate of 100 μl / well. 500 g was centrifuged for 5 minutes to remove the cell medium. The supernatant from the hybridoma culture in the 96-well plate was added to the U-shaped plate, the cells were resuspended, 100 μl was added per well, and the mixture was incubated on ice for 30 minutes. After 5 minutes with 500 g, the supernatant was discarded and the cells were washed once with PBS. 100 μl of FITC-labeled anti-mouse Fab secondary antibody (diluted 1:500 in PBS) was added per well, and 100 μl of FITC-labeled anti-human Fab secondary antibody was added to the positive control antibody. The mixture was incubated on ice for 30 minutes in the dark. After 5 minutes with 500 g, the supernatant was discarded and the cells were washed once with PBS. The cells were resuspended in 50 μl 1× PBS and detected on a bench by FACS.

[0207] A secondary screening for CHO-hCLDN18.1 was performed on the positive clones using the same method as described above, yielding a total of nine hybridoma cell lines that bound to human CLDN18.2 but not to human CLDN18.1. Of these, eight lines were derived from Bal b / c mice and one line was derived from H2L2 whole-human gene transgenic mice, which are specifically shown in Table 2.

[0208] [Table 5] Example 3: Acquisition of antibody gene

[0209] Using molecular biological techniques, antibody light and heavy chain gene sequences were extracted from nine hybridoma cell lines (3G3, 14A5, 25C7, 38F8, 69H9, 46F6, 59C1, 51H10, and HB37A6) obtained from Example 2. Total RNA from the nine hybridoma cells was extracted using an RNA extraction reagent kit (Biomiga, R6311-02). The total RNA was then reverse transcribed using the PrimeScript II 1st Strand cDNA Synthesis Kit (Takara, 6110A) to obtain cDNA. The antibody heavy and light chain variable region sequences were amplified using degenerate primers, a pMD20-T vector (Takara, 6028) was inserted, the cells were ligated and transformed, and then selected clones were sequenced.

[0210] The antibody sequences are shown in Table A. Example 4: Preparation of recombinant CLDN18.2 antibody

[0211] Nine antibodies (3G3, 14A5, 25C7, 38F8, 69H9, 46F6, 59C1, 51H10, and HB37A6) obtained by screening in Example 2, and the control antibody zolbetuximab (abbreviated as Zmab, sequence derived from INN117), were expressed in HEK293 cells (Invitrogen, A14527) in the form of full-length monoclonal antibodies. First, the expression vector was constructed by placing nine pairs of heavy chain variable regions and light chain variable regions at the N-terminus of the human IgG1 heavy chain constant region (SEQ ID NO: 5) and the light chain Kappa constant region (SEQ ID NO: 10), respectively, and constructing a pcDNA3.1 expression vector with an N-terminal signal peptide to obtain a light-heavy chain expression vector. The obtained light-heavy chain expression vectors were rapidly transfected with PEI (Polysciences Inc, 23966) co-transfected versus HEK293 cells and cultured for 7 days. The supernatant was then collected. The supernatant was purified using a Protein A column (Hitrap Mabselect Sure, GE 11-0034-95), ultrafiltered, and replaced with PBS (Gibco, 70011-044). The concentration was detected by the A280 method, and the purity was measured by SEC-HPLC to obtain an antibody solution with a purity of over 95%. Example 5: Measurement of affinity between recombinant CLDN18.2 antibody and antigen by BLI method

[0212] The equilibrium dissociation constant (K) of the antibody of the present invention that binds to human CLDN18.2 using Biolayer Interferometry (BLI) D) was measured. The measurement of affinity by the BLI method was carried out by the conventional method (Estep, P et al., High throughput solution Based measurement of antibody-antigen affinity and epitope binning. MAbs, 2013.5(2):p270-8). The AHC (18-5060, Fortebio) sensor was immersed in SD buffer (1xPBS, 0.1% BSA, 0.05% Tween®-20). 100 μl of SD buffer, each antibody, and human Claudin18.2 protein (P50251802, GenScript) were taken and added to 96-well black polystyrene half-well microplates (Greiner, 675076) respectively. Detection was performed with Fortebio Octet Red96, and the K D value was analyzed with ForteBio Octet analysis software. As shown in Table 3, the affinity data of the antibodies showed that 9 antibodies had high affinity, and among them, except that 3G3 had an affinity equivalent to that of the control antibody Zmab, the others were all superior to the control antibody Zmab.

[0213]

Table 6

[0214] By flow cytometry (FACS), the binding of each of the above 9 antibodies to CHO-S cell lines stably transfected with human CLDN18.2 and human CLDN18.1 obtained in Example 1 (that is, CHO-hCLDN18.2 and CHO-hCLDN18.1 prepared as described in the examples) was measured. Regarding the experimental method, Example 2 was referred to, and the experimental data was analyzed with GraphPad Prism software, and Figures 1 and 2 were obtained. As shown in Figures 1 and 2, all of the above 9 antibodies specifically bind to human CLDN18.2 but do not bind to human CLDN18.1. Example 7: Detection of ADCC activity of CLDN18.2 antibody using a reporter gene.

[0215] The ADCC activity of the nine antibodies listed above was detected in ADCC effector cells (Promega, G7102) containing the luciferase reporter gene. Target cells CHO-hCLDN18.2 and ADCC effector cells in the logarithmic growth phase were isolated and counted. A total of 50 μL was added to a white 96-well base plate in a 1:6 ratio, resulting in a total of 1.75 × 10⁶ samples per well. 5 Having several cells, the above antibody is added to each well and incubated at 37°C and 5% CO2 for 8-10 hours. The concentration of each antibody is set to an initial concentration of 3 nM, and then diluted 3-fold to obtain a total of 9 concentration points. That is, the concentrations used for each antibody are 3 nM, 1 nM, 0.333 nM, 0.111 nM, 0.037 nM, 0.123 nM, 0.0041 nM, 0.0014 nM, and 0.00046 nM. According to the manufacturer's instructions, Bio-Glo TM Fluorescence detection was performed using Luciferase reagent (Promega, G7940). As shown in Figure 3, all nine antibodies possess ADCC activity equivalent to that of the control antibody Zmab. Example 8: Humanization modification of mouse antibodies

[0216] Eight mouse antibodies (3G3, 14A5, 25C7, 38F8, 69H9, 46F6, 59C1, and 51H10) from Example 3 were selected and subjected to humanization modification. The CDR regions of the antibodies were determined, with Abm naming conventions used for the heavy chain CDR1 and Kabat naming conventions used for the remaining CDRs. By alignment of sequence similarity, the human embryonic lineage (germline) gene sequence with the highest similarity to the variable region sequence of the mouse antibody was selected as the template for the frame region of the humanized antibody, and then the CDR region was transplanted into each template. The three-dimensional structure of each antibody was constructed using Discovery Studio software, and the amino acids of the frame region affecting the CDR region were reversed to obtain the humanized antibody sequence. The sequences of the humanized antibodies Hz3G3, Hz14A5, Hz25C7, Hz38F8, Hz69H9, Hz46F6, Hz59C1, and Hz51H10 are referred to in Table A.

[0217] These humanized recombinant antibodies were prepared and purified according to the method described in Example 4 to obtain antibody solutions dissolved in PBS with a purity of over 95%. Example 9: Measurement of CLDN18.2 antibody affinity by SPR method

[0218] Surface plasmon resonance (SPR) was used to determine the equilibrium dissociation constant (K) of eight humanized antibodies (Hz3G3, Hz14A5, Hz25C7, Hz38F8, Hz69H9, Hz46F6, Hz59C1, and Hz51H10) and one whole-human antibody (HB37A6) that bind to human CLDN18.2. Dwas measured. According to the manufacturer's instructions, human Claudin18.2 (GenScrip, P50251802) was coupled to the surface of a CM5 chip (GE Healthcare, 29-1496-03) using an amino coupling reagent kit (GE Healthcare, BR-1006-33). After coupling, 1M ethanolamine was injected to seal the remaining activated sites. According to the manufacturer's instructions, binding and dissociation between the antigen on the chip surface and the antibody in the mobile phase were detected using Biacore (GE Healthcare, T200) to obtain the affinity and kinetic constants. The gradient-diluted antibody (0 nM - 100 nM) was flowed over the chip surface in ascending order of concentration, with a binding time of 180 s and a dissociation time of 600 s. Finally, the chip was regenerated using 10 mM Glycine pH 1.5 (GE Healthcare, BR-1003-54). The data results were dynamically analyzed using a 1:1 binding model with Biacore T200 analysis software. As shown in Table 4, the affinity of all antibodies except Hz25C7 and Hz3G3 is superior to that of the control antibody Zmab.

[0219]

Table 7

[0220] Based on the SPR affinity data, Hz14A5, Hz38F8, Hz69H9, Hz46F6, Hz59C1 and Hz51H10 were selected to detect the ADCC activity by reporter gene. For the experimental procedure, see Example 7. As shown in Figure 4, the humanized antibodies Hz14A5, Hz38F8, Hz69H9, Hz46F6, Hz59C1 and Hz51H10 all showed ADCC activity corresponding to the control antibody. Example 11, Binding of CLDN18.2 Antibody to Tumor Cell Lines

[0221] Based on the above results, one humanized antibody Hz69H9 and one fully human antibody HB37A6 were selected for the following detections. Referring to Example 4, the binding of each of the two antibodies to gastric cancer cell line NUGC-4, gastric cancer cell line KATO III-hCLDN18.2 and pancreatic cancer cell line DAN-G-hCLDN18.2 was measured by FACS. Figure 5 shows that both the humanized antibody Hz69H9 and the fully human antibody HB37A6 have good tumor cell-specific binding and are superior to the control antibody Zmab. Example 12, Detection of CDC Activity of CLDN18.2 Antibody

[0222] The CDC activity of the antibody molecule was detected using the KATO III-CLDN18.2 cell line. 1×10 5 target cells KATO III-hCLDN18.2 were added to a 96-well plate, and then appropriate concentrations of the antibody molecule were added. After culturing at 37°C for 30 minutes, freshly prepared human serum complement (Sigma, S1764) was added. The concentration of each of the antibodies was serially diluted with an initial concentration of 150 μg / ml and diluted 3-fold, with a total of 9 concentration points. The reaction system was placed back in a 37°C incubator and incubated for 3 hours. Then, data was read with a plate reader (ThermoFisher, MULTISKAN FC) using a CCK-8 reagent kit (Dojindo Chemical, CK04). As a result, as shown in Figure 6, Hz69H9 and HB37A6 have CDC corresponding to the control antibody Zmab. Example 13, Detection of ADCC Activity of CLDN18.2 Antibody

[0223] Human peripheral blood mononuclear cells (PBMC, Allcells or Saily) were resuspended using complete medium RPMI-1640 (Hyclone, SH30809.01) + 10% fetal bovine serum (FBS, Hyclone, SH30084.03), and the PBMC were adjusted to 1×10 7The cells / ml were adjusted. DAN-G tumor target cells DAN-G-CLDN18.2, which overexpress NUGC-4 or Claudin18.2, were labeled with Far-Red (Invitrogen) for 10 minutes, washed twice, and then resuspended in complete medium RPMI-1640 (Hyclone, SH30809.01) + 10% fetal bovine serum (FBS, Hyclone, SH30084.03) to a cell concentration of 2 × 10⁶. 5 The concentration was adjusted to 1 cell / ml. PBMCs were mixed with anti-claudin18.2 monoclonal antibodies Hz69H9, HB37A6, and control antibody Zmab (the initial concentration of each antibody was 30 nM, and it was serially diluted 3-fold, resulting in a total of 12 concentration points), incubated at 37°C for 30 min, and then 50 ul of tumor target cells (1 × 10⁶) were added at an effector cell / target cell ratio of 50:1. 4 (1 cell) was added to 50 μl of PBMC effector cells. After incubation at 37°C for 8 hours, the cells were centrifuged and resuspended in propidium iodide (PI, Invitrogen) at a final concentration of 10 μg / ml. Far-Red and PI-double positive cells were detected by flow cytometry (BD, FACSCELESTA). The tumor target cell killing ratio was calculated using FACSDiva software (BD, Celestsa).

[0224] The results for cell-mediated NUGC-4 tumor cytotoxicity, dependent on anti-Claudin 18.2 monoclonal antibody, as shown in Figures 7A and B, show that Hz69H9, HB37A6, and the control antibody Zmab can all dose-dependently mediate cytotoxic killing of NUGC-4 by NK cells, with Hz69H9 and HB37A6 exhibiting stronger maximal tumor cell killing than the control antibody Zmab. Hz69H9 and HB37A6 are shown to have stronger cell-mediated tumor cytotoxic effects. The results for cell-mediated DAN-G tumor cytotoxicity, dependent on anti-Claudin 18.2 monoclonal antibody, as shown in Figures 7C and D, show that Hz69H9, HB37A6, and the control antibody Zmab can all dose-dependently mediate cytotoxic killing of tumor cells by NK cells. Of these, HB37A6 and Hz69H9 both demonstrated stronger mediated maximum killing than the control antibody Zmab in PBMCs from two different donors. As is clear from these results, Hz69H9 and HB37A6 exhibit stronger cell-mediated tumor cytotoxicity compared to the control antibody Zmab. Example 14: Antitumor effect of CLDN18.2 antibody in the body.

[0225] 1. Activity of antibodies against the DAN-G-CLDN18.2 tumor-carrying mouse model. The HZ69H9 and HB37A6 antibodies were selected and tested for their antitumor effects in NOD-SCID mice (female NOD-SCID mice (15g-18g), purchased from Beijing Weitong Lihua Experimental Animal Technology Co., Ltd., 60 mice in total) with human pancreatic cancer. Human pancreatic cancer cells DAN-G-CLDN18.2 constructed in Example 1 were subjected to standard subculture and used for subsequent in vivo experiments. The cells were collected by centrifugation, and DAN-G-CLDN18.2 was dispersed in PBS (1×) to a cell density of 12×10⁶. 5 A cell suspension with a concentration of 6 × 10⁶ cells / ml was obtained. The cell suspension and Matrigel gel were mixed in a 1:1 ratio, resulting in a cell concentration of 6 × 10⁶ cells. 5 A cell suspension was prepared at a concentration of cells / ml. On day 0, 0.2 ml of the cell suspension was taken and subcutaneously inoculated into the right flank region of NOD-SCID mice to create a DAN-G-CLDN18.2 tumor-bearing mouse model.

[0226] After inoculating each mouse with tumor cells for 5 days, the tumor volume was detected, and the tumor volume was 43.36 mm². 3 ~89.47mm 3 Mice within the specified range were divided into S-type groups based on tumor volume (8 mice per group).

[0227] Each mouse was administered hIgG (Equitech-Bio, lot number: 160308-02), Hz69H9, HB37A6, and the control antibody Zmab at a dose of 10 mg / kg per dose, administered on days 5, 9, 12, and 16 after inoculation. Tumor volume was detected 2-3 times per week. Tumor volume measurement: The longest axis (L) and longest short axis (W) of the tumor were measured using calipers, and the tumor volume was calculated using the following formula: V = L × W 2 The calculation was performed using the formula / 2. Body weight was measured using an electronic balance.

[0228] 2. Activity of antibodies against NUCG-4 tumor-bearing mouse models We selected HZ69H9 and HB37A6 antibodies and tested their antitumor effects in NOG mice (female NOG mice (15g-18g), purchased from Beijing Weitong Lihua Experimental Animal Technology Co., Ltd., 100 mice in total) with human gastric cancer. PBMC cells (Allcells) were resuscitated, collected by centrifugation, and the cell density was 2.5 × 10⁶. 6 PBMC cells were dispersed in PBS (1×) to obtain a cell suspension of cells / ml, and on day 0, 0.2 ml of the cell suspension was taken and used for intravenous injection into the eyes of NOG mice to create a humanized NOG mouse model.

[0229] NUGC-4 cells were subjected to standard resuscitation and subculture and used in subsequent in vivo experiments. Cells were collected by centrifugation, and the cell density was 12 × 10⁶. 6 NUGC-4 cells were dispersed in PBS (1×) to a concentration of cells / ml, and then mixed with Matrigel gel in a 1:1 ratio until the cell concentration reached 6×10⁶. 6A cell suspension was prepared at a concentration of cells / ml. On day 5, 0.2 ml of the cell suspension was taken and subcutaneously inoculated into the right flank region of NOG-humanized mice to create a NUCG-4 tumor-bearing mouse model.

[0230] On day 1 after inoculation with tumor cells, mice were randomly divided into groups of 7. Each group received hIgG (Equitech-Bio, lot number: 160308-02), Hz69H9, HB37A6, and the control antibody Zmab. The dosage was 10 mg / kg per dose, administered on days 1, 5, 8, and 12 after inoculation. Tumor volume and body weight were detected 2-3 times per week. Tumor volume was measured using calipers to determine the maximum long axis (L) and maximum short axis (W) of the tumor. The tumor volume was calculated using the following formula: V = L × W 2 The calculation was performed using the formula / 2. Body weight was measured using an electronic balance.

[0231] 3, results As a result, as shown in Figure 8, Hz69H9, HB37A6, and the control antibody Zmab can all suppress tumor growth in the human pancreatic cancer DAN-G-CLDN18.2 mouse model. As shown in Figure 9, Hz69H9 and HB37A6 show better antitumor effects than the control antibody Zmab in the human gastric cancer NUGC-4 mouse model.

[0232] On the 26th day after vaccination, the relative tumor suppression rate (TGI%) was calculated using the following formula: TGI% = 100% * (control group tumor volume - treatment group tumor volume) / (control group tumor volume - control group pre-treatment tumor volume).

[0233] In this DAN-G-CLDN18.2 tumor-bearing mouse model, the TGI rates for Hz69H9 and HB37A6 were 70% and 28%, respectively, while the TGI rate for Zmab was 24%. In the NUCG-4 tumor-bearing mouse model, the TGI rates for Hz69H9 and HB37A6 were 46% and 31%, respectively, while the TGI rate for Zmab was 0%.

[0234] [Table 8-1]

[0235] Table 8-2

[0236] Table 8-3

[0237] Table 8-4

[0238] Table 8-5

[0239] Table 8-6

[0240] Table 8-7

[0241] Table 8-8

[0242] Table 8-9 The present invention includes the following embodiments: <Aspect 1> An anti-CLDN18.2 antibody or its antigen-binding fragment, (i) The three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in Sequence ID No. 4, and the three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in Sequence ID No. 9, (ii) Three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in SEQ ID NO: 15 or 21, and three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in SEQ ID NO: 19 or 22, (iii) Three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in SEQ ID NO: 26 or 27, and three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in SEQ ID NO: 31 or 32, (iv) Three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in SEQ ID NO: 36 or 37, and three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in SEQ ID NO: 40 or 41, (v) Three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in SEQ ID NO: 45 or 48, and three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in SEQ ID NO: 47 or 49, (vi) The three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in SEQ ID NO: 53 or 56, and the three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in SEQ ID NO: 55 or 57, (vii) The three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in SEQ ID NO: 61 or 66, and the three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in SEQ ID NO: 65 or 68, (viii) The three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in SEQ ID NO: 72 or 73, and the three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in SEQ ID NO: 75 or 76, (ix) Three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH as shown in SEQ ID NO: 80 or 85, and three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL as shown in SEQ ID NO: 83 or 86, An anti-CLDN18.2 antibody containing or its antigen-binding fragment. <Aspect 2> An anti-CLDN18.2 antibody or its antigen-binding fragment, (i) HCDR1, HCDR2, and HCDR3 shown in the amino acid sequences of SEQ ID NOs. 1, 2, and 3, respectively, and LCDR1, LCDR2, and LCDR3 shown in the amino acid sequences of SEQ ID NOs. 6, 7, and 8, respectively, (ii) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 12, 13, and 14 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 16, 17, and 18 respectively, (iii) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 12, 20, and 14 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 16, 17, and 18 respectively, (iv) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 12, 93, and 14 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 16, 17, and 18 respectively, (v) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 23, 24, and 25 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 28, 29, and 30 respectively, (vi) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 33, 34, and 35 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 38, 17, and 39 respectively, (vii) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 42, 43, and 44 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 38, 17, and 46 respectively, (viii) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 50, 51, and 52 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 28, 17, and 54 respectively, (ix) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 58, 59, and 60 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 62, 63, and 64 respectively, (x) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 58, 59, and 60 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 67, 63, and 64 respectively, (xi) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 58, 59, and 60 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 11, 63, and 64 respectively, (xii) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 69, 70, and 71 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 38, 17, and 74 respectively, (xiii) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 77, 78, and 79 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 28, 81, and 82 respectively, (xiv) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 77, 84, and 79 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 28, 81, and 82 respectively, (xv) HCDR1, HCDR2, and HCDR3 shown in amino acid sequences 77, 94, and 79 respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequences 28, 81, and 82 respectively, An anti-CLDN18.2 antibody containing or its antigen-binding fragment. <Aspect 3> An antibody or antigen-binding fragment according to embodiment 1 or 2, comprising a heavy chain variable region and / or a light chain variable region, wherein the heavy chain variable region is (i) an amino acid sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with an amino acid sequence selected from SEQ ID NOs: 4, 15, 21, 26, 27, 36, 37, 45, 48, 53, 56, 61, 66, 72, 73, 80, or 85, or consisting of such an amino acid sequence, (ii) Consists of an amino acid sequence selected from sequence numbers 4, 15, 21, 26, 27, 36, 37, 45, 48, 53, 56, 61, 66, 72, 73, 80, or 85, or consists of the above amino acid sequence, (iii) an amino acid sequence having one or more (preferably 10 or fewer, more preferably 5 or fewer, 4 or fewer, 3 or fewer, 2 or fewer, 1 or fewer) amino acid mutations (preferably amino acid substitutions, more preferably amino acid conservative substitutions) compared to an amino acid sequence selected from SEQ ID NOs. 4, 15, 21, 26, 27, 36, 37, 45, 48, 53, 56, 61, 66, 72, 73, 80, or 85, or comprising such an amino acid sequence, preferably the amino acid mutations do not occur in the CDR region, and / or The aforementioned light chain variable region is (i) an amino acid sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with an amino acid sequence selected from SEQ ID NOs. 9, 19, 22, 31, 32, 40, 41, 47, 49, 55, 57, 65, 68, 75, 76, 83, 86, or consisting of such an amino acid sequence, (ii) Consists of an amino acid sequence selected from sequence numbers 9, 19, 22, 31, 32, 40, 41, 47, 49, 55, 57, 65, 68, 75, 76, 83, 86, or consists of such amino acid sequences, (iii) an amino acid sequence having one or more (preferably 10 or fewer, more preferably 5 or fewer, 4 or fewer, 3 or fewer, 2 or fewer, 1 or fewer) amino acid mutations (preferably amino acid substitutions, more preferably amino acid conservative substitutions) compared to an amino acid sequence selected from SEQ ID NOs. 9, 19, 22, 31, 32, 40, 41, 47, 49, 55, 57, 65, 68, 75, 76, 83, 86, or comprising such an amino acid sequence, preferably such amino acid mutations do not occur in the CDR region. An antibody or its antigen-binding fragment. <Aspect 4> An antibody or antigen-binding fragment according to embodiment 1 or 2, (i) VH comprising the amino acid sequence shown in SEQ ID NO: 4 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 9 or an amino acid sequence having at least 90% identity thereto, (ii) VH comprising the amino acid sequence shown in SEQ ID NO: 15 or 21 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 19 or 22 or an amino acid sequence having at least 90% identity thereto, (iii) VH comprising the amino acid sequence shown in SEQ ID NO: 15 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 19 or an amino acid sequence having at least 90% identity thereto, (iv) VH comprising the amino acid sequence shown in SEQ ID NO: 21 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 22 or an amino acid sequence having at least 90% identity thereto, (v) VH comprising the amino acid sequence shown in SEQ ID NO: 26 or 27 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 31 or 32 or an amino acid sequence having at least 90% identity thereto, (vi) VH comprising the amino acid sequence shown in SEQ ID NO: 26 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 31 or an amino acid sequence having at least 90% identity thereto, (vii) VH comprising the amino acid sequence shown in SEQ ID NO: 27 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 32 or an amino acid sequence having at least 90% identity thereto, (viii) VH comprising the amino acid sequence shown in SEQ ID NO: 36 or 37 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 40 or 41 or an amino acid sequence having at least 90% identity thereto, (ix) VH comprising the amino acid sequence shown in SEQ ID NO: 36 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 40 or an amino acid sequence having at least 90% identity thereto, (x) VH comprising the amino acid sequence shown in SEQ ID NO: 37 or an amino acid sequence having at least 90% identity thereto, or consisting of the said amino acid sequence, and VL comprising the amino acid sequence shown in SEQ ID NO: 41 or an amino acid sequence having at least 90% identity thereto, (xi) VH comprising the amino acid sequence shown in SEQ ID NO: 45 or 48 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 47 or 49 or an amino acid sequence having at least 90% identity thereto, (xii) VH comprising the amino acid sequence shown in SEQ ID NO: 45 or an amino acid sequence having at least 90% identity thereto, or consisting of the said amino acid sequence, and VL comprising the amino acid sequence shown in SEQ ID NO: 47 or an amino acid sequence having at least 90% identity thereto, (xiii) VH comprising the amino acid sequence shown in SEQ ID NO: 48 or an amino acid sequence having at least 90% identity thereto, or consisting of the said amino acid sequence, and VL comprising the amino acid sequence shown in SEQ ID NO: 49 or an amino acid sequence having at least 90% identity thereto, (xiv) VH comprising the amino acid sequence shown in SEQ ID NO: 53 or 56 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 55 or 57 or an amino acid sequence having at least 90% identity thereto, (xv) VH comprising the amino acid sequence shown in SEQ ID NO: 53 or an amino acid sequence having at least 90% identity thereto, or consisting of the said amino acid sequence, and VL comprising the amino acid sequence shown in SEQ ID NO: 55 or an amino acid sequence having at least 90% identity thereto, (xvi) VH comprising the amino acid sequence shown in SEQ ID NO: 56 or an amino acid sequence having at least 90% identity thereto, or consisting of the said amino acid sequence, and VL comprising the amino acid sequence shown in SEQ ID NO: 57 or an amino acid sequence having at least 90% identity thereto, (xvii) VH comprising the amino acid sequence shown in SEQ ID NO: 61 or 66 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 65 or 68 or an amino acid sequence having at least 90% identity thereto, (xviii) VH comprising the amino acid sequence shown in SEQ ID NO: 61 or an amino acid sequence having at least 90% identity thereto, or consisting of the said amino acid sequence, and VL comprising the amino acid sequence shown in SEQ ID NO: 65 or an amino acid sequence having at least 90% identity thereto, (xix) VH comprising the amino acid sequence shown in SEQ ID NO: 66 or an amino acid sequence having at least 90% identity thereto, or consisting of the said amino acid sequence, and VL comprising the amino acid sequence shown in SEQ ID NO: 68 or an amino acid sequence having at least 90% identity thereto, (xx) VH comprising the amino acid sequence shown in SEQ ID NO: 72 or 73 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 75 or 76 or an amino acid sequence having at least 90% identity thereto, (xxi) VH comprising the amino acid sequence shown in SEQ ID NO: 72 or an amino acid sequence having at least 90% identity thereto, or consisting of the said amino acid sequence, and VL comprising the amino acid sequence shown in SEQ ID NO: 75 or an amino acid sequence having at least 90% identity thereto, (xxii) VH comprising the amino acid sequence shown in SEQ ID NO: 73 or an amino acid sequence having at least 90% identity thereto, or consisting of the said amino acid sequence, and VL comprising the amino acid sequence shown in SEQ ID NO: 76 or an amino acid sequence having at least 90% identity thereto, (xxiii) VH comprising the amino acid sequence shown in SEQ ID NO: 80 or 85 or an amino acid sequence having at least 90% identity thereto, and VL comprising the amino acid sequence shown in SEQ ID NO: 83 or 86 or an amino acid sequence having at least 90% identity thereto, (xxiv) VH comprising the amino acid sequence shown in SEQ ID NO: 80 or an amino acid sequence having at least 90% identity thereto, or consisting of the said amino acid sequence, and VL comprising the amino acid sequence shown in SEQ ID NO: 83 or an amino acid sequence having at least 90% identity thereto, (xxv) VH, which includes the amino acid sequence shown in SEQ ID NO: 85 or an amino acid sequence having at least 90% identity thereto, or consisting of the amino acid sequence said, and VL, which includes the amino acid sequence shown in SEQ ID NO: 86 or an amino acid sequence having at least 90% identity thereto, An antibody containing an antigen-binding fragment thereof. <Aspect 5> An antibody or antigen-binding fragment according to any one of embodiments 1 to 4, further comprising a heavy chain constant region and / or a light chain constant region. <Pattern 6> An antibody or antigen-binding fragment according to Embodiment 5, The heavy chain constant region HC is (i) an amino acid sequence having at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with an amino acid sequence selected from SEQ ID NO: 5, or consisting of the above amino acid sequence. (ii) comprising an amino acid sequence selected from Sequence ID No. 5, or consisting of the said amino acid sequence, (iii) an amino acid sequence having one or more (preferably 20 or fewer or 10 or fewer, more preferably 5 or fewer, 4 or fewer, 3 or fewer, 2 or fewer, 1 or fewer) amino acid mutations (preferably amino acid substitutions, more preferably amino acid conservative substitutions) compared to an amino acid sequence selected from Sequence ID No. 5, or consisting of the above amino acid sequence and / or The light chain steady region LC is (i) an amino acid sequence having at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with an amino acid sequence selected from SEQ ID NO: 10, or consisting of such an amino acid sequence. (ii) comprising an amino acid sequence selected from Sequence ID No. 10, or consisting of the said amino acid sequence, (iii) an amino acid sequence having one or more (preferably 20 or fewer or 10 or fewer, more preferably 5 or fewer, 4 or fewer, 3 or fewer, 2 or fewer, 1 or fewer) amino acid mutations (preferably amino acid substitutions, more preferably amino acid conservative substitutions) compared to an amino acid sequence selected from Sequence ID No. 10, or consisting of the above amino acid sequence. An antibody or its antigen-binding fragment. <Aspect 7> The antibody or antigen-binding fragment according to embodiment 5 or 6, wherein the amino acid mutation occurs in the Fc region of the heavy chain constant region. <Aspect 8> An antibody or antigen-binding fragment that binds to CLDN18.2 as described in any one of embodiments 1 to 7, wherein the antibody is an antibody or antigen-binding fragment in IgG1 form, IgG2 form, IgG3 form, or IgG4 form, preferably an antibody or antigen-binding fragment in IgG1 form. <Pattern 9> An antibody or antigen-binding fragment thereof that conjugates to CLDN18.2 as described in any one of embodiments 1 to 8, wherein the antibody is a monoclonal antibody. <Aspect 10> An antibody or antigen-binding fragment thereof that binds to CLDN18.2 as described in any one of embodiments 1 to 9, wherein the antibody is a humanized antibody, a human antibody, or a chimeric antibody. <Aspect 11> An antibody or antigen-binding fragment according to any one of embodiments 1 to 10, wherein the antigen-binding fragment is Fab, Fab', Fab'-SH, Fv, single-chain antibody (e.g., scFv), (Fab') 2 An antibody or its antigen-binding fragment, selected from antibody fragments such as single-domain antibodies (e.g., VHH), dAb (domain antibody), or linear antibodies. <Aspect 12> An antibody or antigen-binding fragment according to any one of embodiments 1 to 11, wherein the antibody or antigen-binding fragment is (i) It binds to CLDN18.2 (e.g., human CLDN18.2) with high affinity, but does not bind to CLDN18.1 (e.g., human CLDN18.1). (ii) An equilibrium dissociation constant (K) that is less than approximately 15 nM, and preferably less than or equal to approximately 10 nM, 9.5 nM, 9 nM, 8.5 nM, 8 nM, 7.5 nM, 7 nM, 6.5 nM, 6 nM, 5.5 nM, 5 nM, 4.5 nM, 4 nM, 3.5 nM, or 3 nM. D ) to bind to human CLDN18.2, (iii) It binds to CLDN18.2 on the cell surface but does not bind to CLDN18.1 on the cell surface. (iv) Having ADCC activity or CDC activity equivalent to, for example, ADCC activity or CDC activity equivalent to, or greater than, that of a known antibody (e.g., Zmab), (v) Suppressing tumor cells, for example, tumor cells expressing CLDN18.2, (vi) The tumor growth can be effectively suppressed, and the tumor suppression rate is approximately 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70% or more. An antibody or its antigen-binding fragment having one or more of the following properties. <Aspect 13> An isolated nucleic acid encoding a light chain variable region or a heavy chain, or a light chain or a heavy chain, in an antibody or antigen-binding fragment thereof that binds to CLDN18.2 as described in any one of embodiments 1 to 12. <Aspect 14> A vector comprising the nucleic acid described in embodiment 13, preferably an expression vector. <Aspect 15> A host cell comprising the nucleic acid described in Embodiment 13 or the vector described in Embodiment 14, wherein the host cell is preferably a prokaryotic or eukaryotic cell, more preferably selected from yeast cells, mammalian cells (e.g., 293 cells or CHO cells, e.g., CHO-S cells or HEK293 cells), or other cells to which the preparation of the antibody or its antigen-binding fragment is applied. <Aspect 16> A method for preparing an antibody or antigen-binding fragment that binds to CLDN18.2, comprising culturing host cells as described in embodiment 15 under conditions suitable for the expression of nucleic acids encoding an antibody or antigen-binding fragment that binds to CLDN18.2 as described in any one of embodiments 1 to 12, optionally isolating the antibody or antigen-binding fragment, and optionally recovering the antibody or antigen-binding fragment that binds to CLDN18.2 from the host cells. <Aspect 17> An immune complex comprising an antibody or antigen-binding fragment that binds to CLDN18.2 as described in any one of embodiments 1 to 12, and other substances such as a cytotoxic agent. <Aspect 18> A pharmaceutical composition comprising an antibody or its antigen-binding fragment that conjugates to CLDN18.2 as described in any one of embodiments 1 to 12, or an immune complex as described in embodiment 17, and optionally one or more other therapeutic agents, such as chemotherapeutic agents, cytokines, cytotoxic agents, other antibodies, small molecule drugs, or immunomodulators, and optionally a medicinal auxiliary material. <Aspect 19> A pharmaceutical combination comprising an antibody or its antigen-binding fragment that conjugates to CLDN18.2 as described in any one of embodiments 1 to 12, or an immune complex as described in embodiment 17, and one or more other therapeutic agents, such as chemotherapeutic agents, cytokines, cytotoxic agents, other antibodies, small molecule drugs, or immunomodulators. <Aspect 20> A method for preventing or treating a tumor in a subject, comprising administering to the subject an effective amount of an antibody or antigen-binding fragment thereof that binds to CLDN18.2 as described in any one of embodiments 1 to 12, or an immune complex as described in embodiment 17, or a pharmaceutical composition as described in embodiment 18, or a pharmaceutical combination as described in embodiment 19. <Aspect 21> A method for inducing ADCC and / or CDC in a subject, comprising administering to the subject an effective amount of an antibody or antigen-binding fragment thereof that conjugates to CLDN18.2 as described in any one of embodiments 1 to 12, or an immune complex as described in embodiment 17, or a pharmaceutical composition as described in embodiment 18, or a pharmaceutical combination as described in embodiment 19, wherein the subject is suffering from a tumor. <Aspect 22> The method according to embodiment 20 or 21, wherein the tumor is cancer, and preferably the cancer has elevated levels (e.g., nucleic acid or protein levels) of CLDN18.2, and for example the cancer is pancreatic cancer or gastric cancer. <Aspect 23> A method according to any one of embodiments 20 to 22, further comprising administering to a patient one or more therapies, e.g., a treatment scheme and / or other therapeutic agents, preferably, the treatment scheme comprising surgical treatment and / or radiotherapy, and the other therapeutic agent being selected from chemotherapeutic agents, cytokines, cytotoxic agents, other antibodies, small molecule drugs, or immunomodulators. <Aspect 24> A method for detecting Claudin18.2 in a sample, wherein the method is (a) Contacting the sample with an antibody or antigen-binding fragment described in any one of embodiments 1 to 12 or an immune complex described in embodiment 17, (b) To detect the formation of a complex between the antibody or its antigen-binding fragment and CLDN18.2, This includes, and optionally, the antibody is labeled detectably. method.

Claims

1. An anti-CLDN18.2 antibody or its antigen-binding fragment, (i) The three complementarity determination regions HCDR1, HCDR2 and HCDR3 included in VH shown in Sequence ID No. 4, and the three complementarity determination regions LCDR1, LCDR2 and HCDR3 included in VL shown in Sequence ID No. 9, (ii) The three complementarity determination regions HCDR1, HCDR2 and HCDR3 included in VH shown in Sequence ID No. 15 or 21, and the three complementarity determination regions LCDR1, LCDR2 and HCDR3 included in VL shown in Sequence ID No. 19 or 22, (iii) The three complementarity determination regions HCDR1, HCDR2 and HCDR3 included in VH shown in Sequence ID No. 26 or 27, and the three complementarity determination regions LCDR1, LCDR2 and HCDR3 included in VL shown in Sequence ID No. 31 or 32, (iv) The three complementarity determination regions HCDR1, HCDR2 and HCDR3 included in VH shown in Sequence ID No. 36 or 37, and the three complementarity determination regions LCDR1, LCDR2 and HCDR3 included in VL shown in Sequence ID No. 40 or 41, (v) Three complementarity determination regions HCDR1, HCDR2 and HCDR3 included in VH shown in Sequence ID No. 45 or 48, and three complementarity determination regions LCDR1, LCDR2 and HCDR3 included in VL shown in Sequence ID No. 47 or 49, (vi) The three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in Sequence ID 53 or 56, and the three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in Sequence ID 55 or 57, (vii) The three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH shown in Sequence ID 61, and the three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL shown in Sequence ID 65, or, (viiii) The three complementarity determination regions HCDR1, HCDR2, and HCDR3 included in VH as shown in Sequence ID 80 or 85, and the three complementarity determination regions LCDR1, LCDR2, and LCDR3 included in VL as shown in Sequence ID 83 or 86 Includes, The HCDR1 is determined by the AbM rule, and the HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are determined by the Kabat rule. Anti-CLDN18.2 antibody or its antigen-binding fragment.

2. An anti-CLDN18.2 antibody or its antigen-binding fragment, (i) HCDR1, HCDR2, and HCDR3 as shown in the amino acid sequences of SEQ ID NOs. 1, 2, and 3, respectively, and LCDR1, LCDR2, and LCDR3 as shown in the amino acid sequences of SEQ ID NOs. 6, 7, and 8, respectively, (ii) HCDR1, HCDR2, and HCDR3 shown in the amino acid sequences of SEQ ID NOs. 12, 13, and 14, respectively, and LCDR1, LCDR2, and LCDR3 shown in the amino acid sequences of SEQ ID NOs. 16, 17, and 18, respectively, (iii) HCDR1, HCDR2, and HCDR3 shown in the amino acid sequences of SEQ ID NOs. 12, 20, and 14, respectively, and LCDR1, LCDR2, and LCDR3 shown in the amino acid sequences of SEQ ID NOs. 16, 17, and 18, respectively. (iv) HCDR1, HCDR2, and HCDR3 shown in the amino acid sequences of SEQ ID NOs. 23, 24, and 25, respectively, and LCDR1, LCDR2, and LCDR3 shown in the amino acid sequences of SEQ ID NOs. 28, 29, and 30, respectively. (v) HCDR1, HCDR2, and HCDR3 shown in the amino acid sequences of SEQ ID NOs. 33, 34, and 35, respectively, and LCDR1, LCDR2, and LCDR3 shown in the amino acid sequences of SEQ ID NOs. 38, 17, and 39, respectively, (vi) HCDR1, HCDR2, and HCDR3 shown in the amino acid sequences of SEQ ID NOs. 42, 43, and 44, respectively, and LCDR1, LCDR2, and LCDR3 shown in the amino acid sequences of SEQ ID NOs. 38, 17, and 46, respectively. (vii) HCDR1, HCDR2, and HCDR3 shown in the amino acid sequences of SEQ ID NOs. 50, 51, and 52, respectively, and LCDR1, LCDR2, and LCDR3 shown in the amino acid sequences of SEQ ID NOs. 28, 17, and 54, respectively. (viiii) HCDR1, HCDR2, and HCDR3 shown in amino acid sequence numbers 58, 59, and 60, respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequence numbers 62, 63, and 64, respectively, (ix) HCDR1, HCDR2, and HCDR3 shown in amino acid sequence numbers 77, 78, and 79, respectively, and LCDR1, LCDR2, and LCDR3 shown in amino acid sequence numbers 28, 81, and 82, respectively, or (x) HCDR1, HCDR2, and HCDR3 as shown in amino acid sequence numbers 77, 84, and 79, respectively, and LCDR1, LCDR2, and LCDR3 as shown in amino acid sequence numbers 28, 81, and 82, respectively. An anti-CLDN18.2 antibody containing or its antigen-binding fragment.

3. An antibody or antigen-binding fragment according to claim 1 or 2, comprising a heavy chain variable region and / or a light chain variable region, wherein the heavy chain variable region is (i) an amino acid sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with an amino acid sequence selected from SEQ ID NOs: 4, 15, 21, 26, 27, 36, 37, 45, 48, 53, 56, 61, 80, or 85, or consisting of such an amino acid sequence, (ii) Consists of an amino acid sequence selected from sequence numbers 4, 15, 21, 26, 27, 36, 37, 45, 48, 53, 56, 61, 80, or 85, or consists of the above amino acid sequence, (iii) An amino acid sequence having one to ten or five amino acid mutations compared to an amino acid sequence selected from SEQ ID NOs: 4, 15, 21, 26, 27, 36, 37, 45, 48, 53, 56, 61, 80, or 85, or comprising the above amino acid sequence, wherein the amino acid mutations do not occur in the CDR region, and / or The aforementioned light chain variable region is (i) an amino acid sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with an amino acid sequence selected from SEQ ID NOs: 9, 19, 22, 31, 32, 40, 41, 47, 49, 55, 57, 65, 83, 86, or consisting of such an amino acid sequence, (ii) Consists of an amino acid sequence selected from sequence numbers 9, 19, 22, 31, 32, 40, 41, 47, 49, 55, 57, 65, 83, 86, or consists of the above amino acid sequence, (iii) An amino acid sequence having one to ten or five amino acid mutations compared to an amino acid sequence selected from sequence numbers 9, 19, 22, 31, 32, 40, 41, 47, 49, 55, 57, 65, 83, 86, or consisting of the above amino acid sequence, wherein the amino acid mutations do not occur in the CDR region. An antibody or its antigen-binding fragment.

4. The antibody or antigen-binding fragment according to claim 3, wherein the amino acid mutation is an amino acid substitution or an amino acid conservative substitution, and the conservative substitution is the substitution of an acidic amino acid with another acidic amino acid, a basic amino acid with another basic amino acid, or a neutral amino acid with another neutral amino acid.

5. An antibody or antigen-binding fragment according to any one of claims 1 to 4, (i) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 4, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 9, (ii) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 15 or 21, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 19 or 22, (iii) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 15, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 19, (iv) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 21, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO:

22. (v) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 26 or 27, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 31 or 32, (vi) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 26, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO:

31. (vii) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 27, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO:

32. (viiii) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 36 or 37, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 40 or 41, (ix) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 36, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO:

40. (x) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 37, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO:

41. (xi) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 45 or 48, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 47 or 49, (xi) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 45, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 47, (xiiii) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 48, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 49, (xiv) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 53 or 56, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 55 or 57, (xv) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 53, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO:

55. (xvi) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 56, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO:

57. (xvii) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 61, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 65, (xviiii) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 80 or 85, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 83 or 86, (xix) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 80, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 83, or (xx) VH containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO: 85, and VL containing or consisting of an amino acid sequence having at least 90% identity with the amino acid sequence shown in SEQ ID NO:

86. An antibody or its antigen-binding fragment, including an antibody.

6. An antibody or antigen-binding fragment according to any one of claims 1 to 5, (i) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 4, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 9 (ii) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 15 or 21, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 19 or 22, (iii) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 15, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 19, (iv) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 21, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 22, (v) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 26 or 27, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 31 or 32, (vi) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 26, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 31, (vii) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 27, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 32, (viiii) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 36 or 37, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 40 or 41, (ix) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 36, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 40, (x) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 37, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 41, (xi) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 45 or 48, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 47 or 49, (xi) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 45, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 47, (xiii) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 48, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 49, (xiv) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 53 or 56, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 55 or 57, (xv) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 53, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 55, (xvi) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 56, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 57, (xvii) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 61, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 65, (xviiii) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 80 or 85, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 83 or 86, (xix) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 80, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO: 83, (xx) VH containing or consisting of the amino acid sequence shown in SEQ ID NO: 85, and VL containing or consisting of the amino acid sequence shown in SEQ ID NO:

86. An antibody or its antigen-binding fragment, including an antibody.

7. An antibody or antigen-binding fragment according to any one of claims 1 to 6, further comprising a heavy chain constant region and / or a light chain constant region.

8. The antibody or antigen-binding fragment according to claim 7, The heavy chain steady region is, (i) an amino acid sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with an amino acid sequence selected from Sequence ID No. 5, or comprising the above amino acid sequence. (ii) comprising an amino acid sequence selected from Sequence ID No. 5, or consisting of the said amino acid sequence, (iii) An amino acid sequence having one to ten amino acid mutations compared to the amino acid sequence selected from Sequence ID No. 5, or consisting of the above amino acid sequence, and / or The light chain steady region is, (i) an amino acid sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with an amino acid sequence selected from Sequence ID No. 10, or comprising the above amino acid sequence. (ii) comprising an amino acid sequence selected from Sequence ID No. 10, or consisting of the said amino acid sequence, (iii) An amino acid sequence having one to ten amino acid mutations compared to the amino acid sequence selected from Sequence ID No. 10, or consisting of the above amino acid sequence. An antibody or its antigen-binding fragment.

9. The antibody or antigen-binding fragment according to claim 8, wherein the amino acid mutation is an amino acid substitution or an amino acid conservative substitution, and the conservative substitution is the substitution of an acidic amino acid with another acidic amino acid, a basic amino acid with another basic amino acid, or a neutral amino acid with another neutral amino acid.

10. The antibody or antigen-binding fragment thereof according to claim 8 or 9, wherein the amino acid mutation occurs in the Fc region of the heavy chain constant region.

11. An antibody or antigen-binding fragment according to any one of claims 1 to 10, wherein the antibody is an antibody or antigen-binding fragment in the form of IgG1, IgG2, IgG3, or IgG4.

12. An antibody or antigen-binding fragment according to any one of claims 1 to 11, wherein the antibody is a monoclonal antibody.

13. An antibody or antigen-binding fragment thereof according to any one of claims 1 to 12, wherein the antibody is a humanized antibody, a human antibody, or a chimeric antibody.

14. An antibody or antigen-binding fragment according to any one of claims 1 to 13, wherein the antigen-binding fragment is Fab, Fab', Fab'-SH, Fv, single-chain antibody scFv, (Fab') ２ An antibody or its antigen-binding fragment, selected from antibody fragments such as linear antibodies.

15. An antibody or antigen-binding fragment according to any one of claims 1 to 14, wherein the antibody or antigen-binding fragment is (ii) Equilibrium dissociation constant (K) that is less than 15 nM, or less than or equal to 10 nM, 9.5 nM, 9 nM, 8.5 nM, 8 nM, 7.5 nM, 7 nM, 6.5 nM, 6 nM, 5.5 nM, 5 nM, 4.5 nM, 4 nM, 3.5 nM, or 3 nM. Ｄ ) to bind to human CLDN18.2, (iii) It binds to CLDN18.2 on the cell surface, but does not bind to CLDN18.1 on the cell surface. (iv) Having ADCC activity or CDC activity, (v) Suppressing tumor cells expressing CLDN18.2, (vi) The tumor growth can be effectively suppressed, and the tumor suppression rate is 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70% or more. An antibody or its antigen-binding fragment having one or more of the following properties.

16. An isolated nucleic acid encoding an antibody or an antigen-binding fragment thereof that binds to CLDN18.2 according to any one of claims 1 to 15.

17. An expression vector comprising the nucleic acid described in claim 16.

18. A host cell comprising the nucleic acid according to claim 16 or the vector according to claim 17.

19. The host cell according to claim 18, wherein the host cell is a prokaryotic or eukaryotic cell.

20. A method for preparing an antibody or antigen-binding fragment that binds to CLDN18.2, comprising culturing a host cell according to claim 18 or 19 under conditions suitable for the expression of a nucleic acid encoding the antibody or antigen-binding fragment that binds to CLDN18.2 according to any one of claims 1 to 15.

21. An immune complex comprising an antibody or antigen-binding fragment thereof that binds to CLDN18.2 as described in any one of claims 1 to 15, and a cytotoxic agent.

22. A pharmaceutical composition comprising an antibody or antigen-binding fragment thereof that binds to CLDN18.2 as described in any one of claims 1 to 15, or an immune complex as described in claim 21.

23. The present invention comprises an antibody or antigen-binding fragment thereof that binds to CLDN18.2 as described in any one of claims 1 to 15, or an immune complex as described in claim 21, and one or more other therapeutic agents selected from chemotherapeutic agents, cytokines, cytotoxic agents, small molecule drugs, and immunomodulators. The small molecule is a molecule having a molecular weight of less than 10 kD. Combinations of pharmaceuticals.

24. A pharmaceutical composition according to claim 22, or a pharmaceutical combination according to claim 23, for preventing or treating a tumor in a subject.

25. A pharmaceutical composition according to claim 22, or a pharmaceutical combination according to claim 23, for inducing ADCC and / or CDC in a subject.

26. The pharmaceutical composition or pharmaceutical combination according to claim 25, wherein the subject is suffering from a tumor.

27. The pharmaceutical composition or pharmaceutical combination according to claim 24 or 26, wherein the tumor is cancer.

28. The pharmaceutical composition or pharmaceutical combination according to claim 27, wherein the cancer has an elevated CLDN18.2 protein.

29. The pharmaceutical composition or pharmaceutical combination according to claim 27 or 28, wherein the cancer is pancreatic cancer or gastric cancer.

30. A pharmaceutical composition or pharmaceutical combination according to any one of claims 24 to 29, The aforementioned pharmaceutical composition is administered to a patient in combination with one or more other therapeutic agents. The aforementioned other therapeutic agents are selected from chemotherapeutic agents, cytokines, cytotoxic agents, small molecule drugs, and immunomodulators. The small molecule is a molecule having a molecular weight of less than 10 kD. Pharmaceutical composition or combination of pharmaceuticals.

31. Use in the manufacture of a pharmaceutical for the prevention or treatment of tumors in a subject, or for the induction of ADCC and / or CDC in a subject, of an antibody or antigen-binding fragment thereof that conjugates to CLDN18.2 as described in any one of claims 1 to 15, an immune complex as described in claim 21, a pharmaceutical composition as described in claim 22, or a pharmaceutical combination as described in claim 23.

32. A method for detecting Claudin 18.2 in a sample, wherein the method is: (a) Contacting the sample with the antibody or antigen-binding fragment described in any one of claims 1 to 15 or the immune complex described in claim 21, (b) To detect the formation of a complex between the antibody or its antigen-binding fragment and CLDN18.2, including, method.

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