Anti-ERBB3 antibodies or their antigen-binding fragments and their pharmaceutical uses

Abstract

This relates to anti-ERBB3 antibodies or their antigen-binding fragments and their pharmaceutical uses, particularly to fully human antibodies against the ERBB3 receptor or their antigen-binding fragments and their pharmaceutical uses. It also includes pharmaceutical compositions comprising fully human anti-ERBB3 antibodies or their antigen-binding fragments, and their use as anticancer drugs.

Description

Technical Field

[0001] This invention relates to ERBB3 antibodies or antigen-binding fragments thereof, and further, to fully human ERBB3 antibodies or antigen-binding fragments thereof comprising a CDR region; the invention also relates to pharmaceutical compositions comprising said fully human ERBB3 antibodies or antigen-binding fragments thereof, and their use as diagnostic and therapeutic agents for ERBB3-related diseases. Background Technology

[0002] ERBB receptors are widely expressed in neurons, epithelial cells, and mesenchymal cells, and are involved in the development of the cardiovascular, nervous, musculoskeletal, and other organs, as well as in cancer pathogenesis. There are four families of ERBB receptor proteins: EGFR, ERBB2, ERBB3, and ERBB4, all membrane proteins with similar molecular structures, including an extracellular domain (ECD), a transmembrane domain, an intracellular domain with tyrosine kinase activity, and a C-terminus. The ECD can be further subdivided into four subdomains: subdomains I, II, III, and IV (BMC Bioinformatics 2001, 2:4; Mol Cell 2003, 11:507-17). Subdomains I and III are rich in leucine and are ligand-binding domains; subdomains II and IV are rich in cysteine ​​and are dimer-forming domains. Except for ERBB2, the other three ERBB receptors bind to subdomains II and IV in the inactive state, opening upon ligand binding and activation, exposing subdomain II and forming a dimer. Currently, EGFR and ERBB2 are the most studied, and corresponding targeted drug development is more intensive. In recent years, ERBB3 has received increasing attention. The ERBB3 bypass pathway plays a crucial role in EGFR and ERBB2-related drug resistance, and ERBB3 is highly expressed in various tumors including breast cancer, lung cancer, prostate cancer, colorectal cancer, ovarian cancer, gastric cancer, bladder cancer, and melanoma. Therefore, ERBB3 is another potential target for cancer therapy. ERBB3 has two ligands, NRG1 and NRG2, which can activate its kinase activity. Activated ERBB3 can form heterodimers with EGFR or ERBB2, phosphorylating the latter and transmitting signals to downstream pathways, promoting tumor cell growth and proliferation. Furthermore, in cancer, ERBB3 can also transmit signals through "crosstalk" with other RTKs, such as forming complexes with IGF1R, FGFR2, and HGFR (c-Met) (BioDrugs 2017, 31:63-73), demonstrating the important role ERBB3 plays in tumor growth.

[0003] Currently, therapeutic strategies targeting ERBB3 follow several mechanisms: 1) locking ERBB3 in an inactive state (e.g., CDX-3379); 2) capturing ERBB3's ligand NRG (e.g., RB200); 3) blocking the binding of ERBB3 to its ligand (e.g., U3-1287); 4) promoting ERBB3 endocytosis (antibody-drug conjugates); 5) blocking the dimerization of ERBB3 with other EGFR family members; and 6) recruiting immune cells to kill cancer cells expressing endogenous ERBB3. Targeted therapies for ERBB3 can utilize these mechanisms, including monoclonal antibodies, bispecific antibodies, anti-ERBB3 vaccines, ligand traps, RNA inhibitors that lock ERBB3, and small molecules that inhibit ERBB3 kinase activity. Among these, the development of antibodies targeting ERBB3 is particularly promising.

[0004] In clinical studies, a murine ERBB3 antibody has significantly inhibited tumor growth in patients (cited data from Celldex). Currently, ERBB3 antibodies under development include humanized antibodies derived from murine antibodies, but these humanized antibodies exhibit higher immunogenicity during immunization compared to fully human antibodies without murine antibody components, which is a disadvantage for human application. Other investigational ERBB3 antibody drugs utilize phage display technology to obtain fully human antibodies, thus addressing the immunogenicity issue.

[0005] Phage display technology involves fusing exogenous proteins or peptides with phage coat proteins, thereby expressing the exogenous protein on the surface of the phage. A phage antibody library is an antibody library established using a comprehensive set of techniques, combining phage display technology, PCR amplification technology, and protein expression technology.

[0006] Phage libraries generally include synthetic libraries, immune libraries, and natural libraries, with natural libraries being the most commonly used. Natural libraries are typically constructed from human peripheral blood immune cells, resulting in fully human antibody libraries. Their biggest advantage is that they can obtain highly diverse, fully human antibodies already produced by the human body without requiring additional in vivo immunization. In addition, phage antibody libraries offer the following advantages: ① They achieve genotype and phenotype consistency. Furthermore, the experimental method is simple and rapid; traditional hybridoma antibody production methods take months, while antibody library technology only takes a few weeks. ② They express fully human antibodies with small molecular weights, primarily expressed as active fragments such as Fab and scFV, exhibiting significant advantages in tissue penetration compared to intact antibodies. ③ They offer a large screening capacity; hybridoma technology screens from thousands of clones, while antibody library technology can select from millions or even billions of molecules, resulting in a much wider variety of antibodies. ④ It has a wide range of applications and adopts a prokaryotic expression system. Its advantages are more obvious when it is produced on a large scale (Curr Opin Biotechnol. 2002 Dec; 13(6):598-602; Immunotechnology, 2013, 48(13):63-73).

[0007] Currently, there are patents such as WO2007077028 that report antibodies against ERBB3. The vast majority of these are murine or humanized antibodies, while some are fully human antibodies obtained from phage libraries. Both domestically and internationally, most of these are in the early clinical or discovery stages, and there are no antibody drugs targeting ERBB3 on the market yet. Therefore, it is necessary to further develop fully human antibodies against ERBB3 with higher activity, higher affinity, and higher stability for research and application in the treatment of related diseases. Summary of the Invention

[0008] This invention provides an anti-ERBB3 antibody or its antigen-binding fragment, particularly relating to a fully human anti-ERBB3 antibody or its antigen-binding fragment, wherein the anti-ERBB3 antibody or its antigen-binding fragment comprises: a variable region of the antibody heavy chain and a variable region of the light chain; wherein the variable region of the antibody heavy chain comprises at least one HCDR selected from the following sequences: SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3 or SEQ ID NO:4; and the variable region of the antibody light chain comprises at least one LCDR selected from the following sequences: SEQ ID NO:5, SEQ ID NO:6 or SEQ ID NO:7.

[0009] The present invention also relates to a preferred embodiment, an anti-ERBB3 antibody or its antigen-binding fragment as described above, wherein:

[0010] The antibody heavy chain variable region comprises HCDR1 shown in SEQ ID NO:1, HCDR2 shown in SEQ ID NO:2, and HCDR3 shown in SEQ ID NO:4; or,

[0011] The antibody heavy chain variable region includes HCDR1 shown in SEQ ID NO:1, HCDR2 shown in SEQ ID NO:3, and HCDR3 shown in SEQ ID NO:4.

[0012] The present invention also relates to a preferred embodiment, an anti-ERBB3 antibody or an antigen-binding fragment thereof as described above, wherein the variable region of the antibody light chain comprises:

[0013] LCDR1 shown in SEQ ID NO:5, LCDR2 shown in SEQ ID NO:6, and LCDR3 shown in SEQ ID NO:7.

[0014] The present invention also relates to a preferred embodiment, an anti-ERBB3 antibody or its antigen-binding fragment as described above, comprising a heavy chain variable region and a light chain variable region, wherein:

[0015] The antibody heavy chain variable region includes HCDR1 shown in SEQ ID NO:1, HCDR2 shown in SEQ ID NO:2, and HCDR3 shown in SEQ ID NO:4; the antibody light chain variable region includes LCDR1 shown in SEQ ID NO:5, LCDR2 shown in SEQ ID NO:6, and LCDR3 shown in SEQ ID NO:7.

[0016] The present invention also relates to a preferred embodiment, an anti-ERBB3 antibody or its antigen-binding fragment as described above, comprising a heavy chain variable region and a light chain variable region, wherein:

[0017] The antibody heavy chain variable region includes: HCDR1 shown in SEQ ID NO:1, HCDR2 shown in SEQ ID NO:3, and HCDR3 shown in SEQ ID NO:4; the antibody light chain variable region includes: LCDR1 shown in SEQ ID NO:5, LCDR2 shown in SEQ ID NO:6, and LCDR3 shown in SEQ ID NO:7.

[0018] The present invention also relates to a preferred embodiment, an anti-ERBB3 antibody or an antigen-binding fragment thereof as described above, wherein the heavy chain variable region of the antibody is selected from the heavy chain variable regions shown in the following sequences: SEQ ID NO:8 or SEQ ID NO:9.

[0019] The present invention also relates to a preferred embodiment, an anti-ERBB3 antibody or an antigen-binding fragment thereof as described above, wherein the variable region of the antibody light chain is SEQ ID NO:10.

[0020] The present invention also relates to a preferred embodiment, an anti-ERBB3 antibody or an antigen-binding fragment thereof as described above, wherein the antibody comprises: the heavy chain variable region shown in SEQ ID NO:8, and the light chain variable region shown in SEQ ID NO:10; or,

[0021] The anti-ERBB3 antibody or its antigen-binding fragment includes the heavy chain variable region shown in SEQ ID NO:9 and the light chain variable region shown in SEQ ID NO:10.

[0022] In a preferred embodiment of the present invention, the anti-ERBB3 antibody or its antigen-binding fragment further comprises a heavy chain constant region derived from human IgG1, IgG2, IgG3 or IgG4 or its mutants.

[0023] In a further preferred embodiment of the present invention, the anti-ERBB3 antibody or its antigen-binding fragment further comprises a heavy chain constant region of human IgG1 or a variant thereof;

[0024] In a further preferred embodiment of the present invention, the anti-ERBB3 antibody or its antigen-binding fragment further comprises a human IgG1 heavy chain constant region;

[0025] In a further preferred embodiment of the present invention, the anti-ERBB3 antibody or its antigen-binding fragment further comprises a heavy chain constant region as shown in SEQ ID NO:17;

[0026] In a further preferred embodiment of the present invention, the anti-ERBB3 antibody or its antigen-binding fragment further comprises a light chain constant region derived from the human κ chain, λ chain or its mutants;

[0027] In a further preferred embodiment of the present invention, the anti-ERBB3 antibody or its antigen-binding fragment further comprises a light chain constant region derived from the human λ chain.

[0028] In a further preferred embodiment of the present invention, the anti-ERBB3 antibody or its antigen-binding fragment further comprises a light chain constant region as shown in SEQ ID NO:18.

[0029] In a preferred embodiment of the present invention, the anti-ERBB3 antibody or its antigen-binding fragment comprises a heavy chain variable region selected from SEQ ID NO:8, SEQ ID NO:9, or a heavy chain variable region having at least 70%, 75%, 80%, 85%, 90%, 95%, or 99% homology thereto.

[0030] In a preferred embodiment of the present invention, the anti-ERBB3 antibody or its antigen-binding fragment comprises a light chain variable region SEQ ID NO:10, or a light chain variable region having at least 70%, 75%, 80%, 85%, 90%, 95%, or 99% homology thereto.

[0031] The present invention also relates to a preferred embodiment, an anti-ERBB3 antibody or an antigen-binding fragment thereof as described above, wherein the heavy chain of the antibody is selected from heavy chains containing the following sequence: SEQ ID NO:11 or SEQ ID NO:12.

[0032] The present invention also relates to a preferred embodiment, an anti-ERBB3 antibody or an antigen-binding fragment thereof as described above, wherein the antibody light chain is SEQ ID NO:13.

[0033] The present invention also relates to a preferred embodiment, an anti-ERBB3 antibody or its antigen-binding fragment as described above, wherein,

[0034] The anti-ERBB3 antibody comprises the heavy chain shown in SEQ ID NO:11 and the light chain shown in SEQ ID NO:13; or,

[0035] The anti-ERBB3 antibody comprises the heavy chain shown in SEQ ID NO:12 and the light chain shown in SEQ ID NO:13.

[0036] The present invention also relates to a preferred embodiment, an anti-ERBB3 antibody or an antigen-binding fragment thereof as described above, wherein the anti-ERBB3 antibody or the antigen-binding fragment thereof comprises a heavy chain selected from the following: SEQ ID NO: 11, SEQ ID NO: 12, or a full-length heavy chain having at least 80%, 85%, 90%, 95% or 99% homology thereto.

[0037] The present invention also relates to a preferred embodiment, an anti-ERBB3 antibody or an antigen-binding fragment thereof as described above, wherein the anti-ERBB3 antibody or the antigen-binding fragment thereof comprises a light chain SEQ ID NO: 13, or a full-length light chain having at least 80%, 85%, 90%, 95%, or 99% homology thereto.

[0038] The present invention further provides a polynucleotide encoding the above-mentioned anti-ERBB3 antibody or its antigen-binding fragment.

[0039] The present invention further provides an expression vector containing the above-mentioned polynucleotides.

[0040] The present invention further provides a host cell in which the above-described expression vector is introduced or contained.

[0041] In a preferred embodiment of the present invention, the host cell is a bacterium, preferably Escherichia coli.

[0042] In a preferred embodiment of the present invention, the host cell is yeast, preferably Pichia pastoris.

[0043] In a preferred embodiment of the present invention, the host cell is a mammalian cell, preferably a CHO cell or a HEK293 cell.

[0044] The present invention further provides a method for producing anti-ERBB3 antibody or its antigen-binding fragment, comprising the steps of:

[0045] a) Culturing the aforementioned host cells;

[0046] b) Isolation of fully human antibodies from cultures; and

[0047] c) Purify the antibody.

[0048] The present invention further provides a pharmaceutical composition comprising the above-described anti-ERBB3 antibody or its antigen-binding fragment, and pharmaceutically acceptable excipients, diluents or carriers.

[0049] The present invention further provides a detection or diagnostic reagent containing the above-mentioned anti-ERBB3 antibody or its antigen-binding fragment, as well as excipients, diluents or carriers that can be used for detection or diagnosis.

[0050] The present invention further provides the use of the above-described anti-ERBB3 antibody or its antigen-binding fragment or the above-described composition in the preparation of a medicament for treating or preventing ERBB3-mediated diseases or conditions.

[0051] The present invention further provides the use of the above-mentioned anti-ERBB3 antibody or its antigen-binding fragment or the above-mentioned detection or diagnostic reagent in the preparation of reagents, wherein the reagents are used to detect, diagnose, and prognose ERBB3-mediated diseases or conditions.

[0052] In a preferred embodiment of the present invention,

[0053] The aforementioned disease or symptom is cancer;

[0054] Cancers that express or overexpress ERBB3 are preferred;

[0055] More preferably, breast cancer, ovarian cancer, prostate cancer, endometrial cancer, thyroid cancer, kidney cancer, lung cancer, stomach cancer, colon cancer, bladder cancer, cervical cancer, gallbladder cancer, pancreatic cancer, testicular cancer, soft tissue sarcoma, head and neck cancer, glioma, or melanoma.

[0056] In a preferred embodiment of the present invention, the above-described anti-ERBB3 antibody or its antigen-binding fragment or the above-described composition is used for detecting, diagnosing, and prognosing ERBB3-mediated diseases; the diseases are selected from: breast cancer, ovarian cancer, prostate cancer, endometrial cancer, thyroid cancer, kidney cancer, lung cancer, gastric cancer, colon cancer, bladder cancer, cervical cancer, gallbladder cancer, pancreatic cancer, testicular cancer, soft tissue sarcoma, head and neck cancer, glioma, or melanoma.

[0057] The present invention further provides a method for treating or preventing ERBB3-mediated diseases, comprising the steps of:

[0058] The subject is provided with a therapeutically effective or preventatively effective amount of the above-described anti-ERBB3 antibody or its antigen-binding fragment; or the subject is provided with a therapeutically effective or preventatively effective amount of the above-described pharmaceutical composition; wherein the ERBB3-mediated disease is selected from: breast cancer, ovarian cancer, prostate cancer, endometrial cancer, thyroid cancer, kidney cancer, lung cancer, gastric cancer, colon cancer, bladder cancer, cervical cancer, gallbladder cancer, pancreatic cancer, testicular cancer, soft tissue sarcoma, head and neck cancer, glioma, or melanoma. Detailed Implementation Invention Details

[0060] I. Terminology

[0061] To facilitate understanding of this invention, certain technical and scientific terms are specifically defined below. Unless otherwise expressly defined elsewhere in this document, all other technical and scientific terms used herein have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains.

[0062] The amino acid three-letter codes and single-letter codes used in this invention are as described in J. Biol. Chem, 243, p3558 (1968).

[0063] The term "antibody" used in this invention refers to immunoglobulin, which is a tetrapeptide chain structure composed of two identical heavy chains and two identical light chains linked by interchain disulfide bonds. The amino acid composition and sequence of the constant region of the heavy chain of immunoglobulins differ, thus their antigenicity also differs. Accordingly, immunoglobulins can be divided into five classes, or isotypes of immunoglobulins: IgM, IgD, IgG, IgA, and IgE, with their corresponding heavy chains being μ, δ, γ, α, and ε chains, respectively. Within the same class of Ig, based on differences in the amino acid composition of its hinge region and the number and position of disulfide bonds in its heavy chain, it can be further divided into different subclasses; for example, IgG can be divided into IgG1, IgG2, IgG3, and IgG4. The light chains are classified as κ chains or λ chains based on differences in their constant regions. Each of the five classes of Ig can have either a κ chain or a λ chain.

[0064] The antibody light chain variable region of the present invention may further include a light chain constant region, wherein the light chain constant region comprises human or mouse κ, λ chains or variants thereof.

[0065] The variable region of the antibody heavy chain described in this invention may further include a constant region of the heavy chain, wherein the constant region of the heavy chain includes human or mouse IgG1, IgG2, IgG3, IgG4 or variants thereof.

[0066] The sequence of approximately 110 amino acids near the N-terminus of both the antibody heavy and light chains varies considerably and is known as the variable region (V region); the remaining amino acid sequences near the C-terminus are relatively stable and are known as the constant region (C region). The variable region includes three hypervariable regions (HVR) and four relatively conserved backbone regions (FR). The three hypervariable regions determine the antibody's specificity and are also called complementarity-determining regions (CDR). Each light chain variable region (VL) and heavy chain variable region (VH) consists of three CDR regions and four FR regions, arranged in the following order from the amino terminus to the carboxyl terminus: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4. The three CDR regions of the light chain refer to LCDR1, LCDR2, and LCDR3; the three CDR regions of the heavy chain refer to HCDR1, HCDR2, and HCDR3. The CDR amino acid residues in the VL and VH regions of the antibody or antigen-binding fragment described in this invention conform to the known Kabat, Chothia, or ABM definition rules in terms of number and position (http: / / bioinf.org.uk / abs / ).

[0067] The term "antigen-presenting cell" or "APC" refers to a cell that displays a foreign antigen complexed with MHC on its surface. T cells recognize this complex using T cell receptors (TCRs). Examples of APCs include, but are not limited to, dendritic cells (DCs), peripheral blood mononuclear cells (PBMCs), monocytes, B lymphoblasts, and monocyte-derived dendritic cells.

[0068] The term "antigen presentation" refers to the process by which APCs capture antigens and make them available for recognition by T cells, for example, as a component of MHC-I / MHC-II conjugates.

[0069] The term "recombinant human antibody" includes human antibodies prepared, expressed, created, or isolated by recombinant methods, the techniques and methods of which are well known in the art, such as:

[0070] 1. Antibodies isolated from transgenic, transchromosomal animals (e.g., mice) of the human immunoglobulin gene or hybridomas prepared therefrom;

[0071] 2. Antibodies isolated from host cells transformed to express antibodies, such as transfected tumors;

[0072] 3. Antibodies isolated from recombinant human antibody libraries; and

[0073] 4. Antibodies prepared, expressed, created, or isolated by methods such as splicing human immunoglobulin gene sequences into other DNA sequences.

[0074] These recombinant human antibodies contain variable and constant regions that utilize specific human germline immunoglobulin sequences encoded by germline genes, but also include subsequent rearrangements and mutations that occur during antibody maturation.

[0075] The term "human antibody" includes antibodies having variable and constant regions of human germline immunoglobulin sequences. Human antibodies of the present invention may include amino acid residues not encoded by human germline immunoglobulin sequences (e.g., mutations introduced by random or site-specific mutagenesis in vitro or by somatic mutations in vivo). However, the term "human antibody" does not include antibodies in which a CDR sequence derived from another mammalian species (such as a mouse) has been grafted onto a human backbone sequence (i.e., "humanized antibody").

[0076] The term "antigen-binding fragment" refers to an antigen-binding fragment of an antibody and antibody analogues, which typically includes at least a portion of the antigen-binding region or variable region (e.g., one or more CDRs) of the parent antibody. The antibody fragment retains at least some of the binding specificity of the parent antibody. Typically, when activity is expressed on a molar basis, the antibody fragment retains at least 10% of the parent antibody's binding activity. Preferably, the antibody fragment retains at least 20%, 50%, 70%, 80%, 90%, 95%, or 100% or more of the parent antibody's binding affinity to the target. Examples of antigen-binding fragments include, but are not limited to: Fab, Fab', F(ab')2, Fv fragments, linear antibodies, single-chain antibodies, nanobodies, domain antibodies, and multispecific antibodies. A review of engineered antibody variants is available in Holliger and Hudson, 2005, Nat. Biotechnol. 23: 1126-1136.

[0077] The term "Fab fragment" consists of a light chain, a heavy chain (CH1), and a variable region. The heavy chain of a Fab molecule cannot form a disulfide bond with another heavy chain molecule.

[0078] The term "Fc" region contains two heavy chain segments that contain the CH1 and CH2 domains of the antibody. The two heavy chain segments are held together by two or more disulfide bonds and through the hydrophobic interaction of the CH3 domain.

[0079] The term "Fab' fragment" contains a portion of a light chain and a heavy chain containing the VH domain and the CH1 domain, as well as the region between the CH1 and CH2 domains, thereby allowing interchain disulfide bonds to form between the two heavy chains of two Fab' fragments to form the F(ab')2 molecule.

[0080] The term "F(ab')2 segment" contains two light chains and two heavy chains containing portions of a constant region between the CH1 and CH2 domains, thereby forming an interchain disulfide bond between the two heavy chains. Therefore, the F(ab')2 segment consists of two Fab' segments held together by the disulfide bond between the two heavy chains.

[0081] The term "Fv region" includes the variable region from both the heavy chain and the light chain, but lacks the constant region.

[0082] The term "multispecific antibody," used in its broadest sense, encompasses antibodies that exhibit multi-epitope specificity. These multispecific antibodies include, but are not limited to: antibodies comprising a heavy chain variable region (VH) and a light chain variable region (VL), wherein the VH-VL unit exhibits multi-epitope specificity; antibodies having two or more VL and VH regions, each VH-VL unit binding to a different target or a different epitope of the same target; antibodies having two or more single variable regions, each single variable region binding to a different target or a different epitope of the same target; full-length antibodies, antibody fragments, diabodies, bispecific diabodies, triabodies, and antibody fragments covalently or non-covalently linked together, etc.

[0083] The term "single-chain antibody" refers to a single-chain recombinant protein composed of the heavy chain variable region (VH) and light chain variable region (VL) of an antibody linked by a linker peptide. It is the smallest antibody fragment with a complete antigen-binding site.

[0084] The term "domain antibody fragment" refers to an immunoglobulin fragment with immunological function containing only the heavy chain variable region or the light chain variable region. In some cases, two or more VH regions are covalently linked to peptide linkers to form a bivalent domain antibody fragment. The two VH regions of a bivalent domain antibody fragment can target the same or different antigens.

[0085] The term "binding to ERBB3" refers to the ability to interact with human ERBB3.

[0086] The term "antigen binding site" refers to the three-dimensional spatial site recognized by the antibody or antigen binding fragment of this invention.

[0087] The term "epitope" refers to a site on an antigen that specifically binds to an immunoglobulin or antibody. Epitopes can be formed from adjacent amino acids or from non-adjacent amino acids arranged side-by-side through the ternary folding of a protein. Epitopes formed from adjacent amino acids are generally retained upon exposure to denaturing solvents, while epitopes formed through ternary folding are generally lost upon treatment with denaturing solvents. Epitopes typically comprise at least 3-15 amino acids in a distinctive spatial conformation. Methods for determining which epitopes bind to a given antibody are well known in the art, including immunoblotting and immunoprecipitation assays. Methods for determining the spatial conformation of epitopes include techniques in the art and those described herein, such as X-ray crystallography and two-dimensional nuclear magnetic resonance.

[0088] The terms "specific binding" and "selective binding" refer to the binding of an antibody to a predetermined epitope on an antigen. Typically, when human ERBB3 is used as the analyte and an antibody as the ligand, the antibody binds at approximately less than 10^66 ppm when measured in an instrument using surface plasmon resonance (SPR) technology. -7 M or even smaller equilibrium dissociation constant (K) D An antibody that recognizes a predetermined antigen binds to it, and its affinity for the predetermined antigen is at least twice that for a nonspecific antigen other than the predetermined antigen or closely related antigens (such as BSA). The term "antibody that recognizes an antigen" may be used interchangeably with the term "antibody that specifically binds."

[0089] The term "cross-reactivity" refers to the ability of the antibodies of this invention to bind to ERBB3 from different species. For example, the antibodies of this invention that bind to human ERBB3 can also bind to ERBB3 from another species. Cross-reactivity is measured by detecting specific reactivity with purified antigens in binding assays (e.g., SPR and ELISA), or binding or functional interaction with cells physiologically expressing ERBB3. Methods for determining cross-reactivity include standard binding assays as described herein, such as surface plasmon resonance (SPR) analysis, or flow cytometry.

[0090] The terms “inhibition” and “blocking” are used interchangeably and encompass both partial and complete inhibition / blocking. Inhibition / blocking of a ligand preferably reduces or alters the normal level or type of activity that occurs when ligand binding occurs without inhibition or blocking. Inhibition and blocking are also intended to include any measurable reduction in ligand binding affinity upon contact with an anti-ERBB3 antibody compared to a ligand not contacted with an anti-ERBB3 antibody.

[0091] The term “growth inhibition” (e.g., involving cells) is intended to include any measurable reduction in cell growth.

[0092] The terms “inducing an immune response” and “enhancing an immune response” are used interchangeably and refer to the stimulation of an immune response by a specific antigen (i.e., passive or adaptive). The term “inducing” in relation to induced CDC or ADCC refers to the stimulation of a specific direct cell-killing mechanism.

[0093] The "ADCC" mentioned in this invention, namely antibody-dependent cell-mediated cytotoxicity, refers to the direct killing of antibody-coated target cells by cells expressing Fc receptors through recognition of the Fc fragment of antibodies. The ADCC effector function of antibodies can be enhanced, reduced, or eliminated by modifying the Fc fragment of IgG. The modification refers to mutation in the constant region of the antibody's heavy chain.

[0094] The engineered antibodies or antigen-binding fragments of this invention can be prepared and purified using conventional methods. The corresponding antibody cDNA sequence can be cloned and recombined into a GS expression vector. The recombinant immunoglobulin expression vector can stably transfect CHO cells. As a more preferred prior art, mammalian expression systems lead to glycosylation of the antibody, particularly at the highly conserved N-terminus of the FC region. Stable clones are obtained by expressing antibodies that specifically bind to human antigens. Positive clones are scaled up in serum-free medium in a bioreactor to produce antibodies. The culture medium secreting antibodies can be purified and collected using conventional techniques. The antibodies can be concentrated by filtration using conventional methods. Soluble mixtures and polymers can also be removed using conventional methods, such as molecular sieving or ion exchange. The resulting product should be immediately frozen, such as at -70°C, or lyophilized.

[0095] "Administration," "giving," and "treatment," when applied to animals, humans, experimental subjects, cells, tissues, organs, or biological fluids, refer to the contact of an exogenous drug, therapeutic agent, diagnostic agent, or composition with the animal, human, subject, cell, tissue, organ, or biological fluid. "Administration," "giving," and "treatment" can refer to, for example, therapeutic, pharmacokinetic, diagnostic, research, and experimental methods. Cellular treatment includes contact between a reagent and cells, as well as contact between a reagent and a fluid, wherein the fluid is in contact with the cells. "Administration," "giving," and "treatment" also mean the treatment of, for example, cells, by means of a reagent, diagnostic agent, conjugate composition, or by means of another cell in vitro and ex vivo. "Treatment," when applied to humans, veterinary, or research subjects, refers to therapeutic treatment, preventative or prophylactic measures, research, and diagnostic applications.

[0096] "Treatment" means administering an oral or topical therapeutic agent, such as an antibody comprising any of the present invention, to a patient who has one or more symptoms of a disease, and the therapeutic agent is known to have a therapeutic effect on these symptoms. Typically, a therapeutic agent is administered in a treated patient or population in an amount that effectively relieves one or more symptoms of a disease, whether by inducing the regression of such symptoms or inhibiting their progression to any clinically measured extent. The amount of a therapeutic agent that effectively relieves any specific disease symptom (also referred to as a "therapeuticly effective amount") can vary depending on a variety of factors, such as the patient's disease state, age, and weight, and the drug's ability to produce the desired therapeutic effect in the patient. Whether the disease symptoms have been relieved can be evaluated using any clinical test method commonly used by a physician or other healthcare professional to assess the severity or progression of the symptoms. Although embodiments of the present invention (e.g., treatment methods or articles) may be ineffective in alleviating the symptoms of the target disease present in every patient, they should be determined to reduce the symptoms of the target disease in a statistically significant number of patients by any statistical test known in the art, such as the Student t-test, chi-square test, U-test according to Mann and Whitney, Kruskal-Wallis test (H-test), Jonckheere-Terpstra test, and Wilcoxon test.

[0097] The term “consistently composed of” or variations thereof, used throughout the specification and claims, means that all said elements or groups of elements are included, and optionally include other elements that are similar to or different in nature from said elements, which do not significantly alter or introduce new properties to the specified dosing regimen, method or composition.

[0098] The term "naturally occurring" as used in this invention refers to the fact that the object can be found in nature. For example, a polypeptide or polynucleotide sequence that exists in organisms (including viruses) that can be isolated from natural sources and has not been intentionally modified artificially in a laboratory is considered naturally occurring.

[0099] An "effective dose" includes a dose sufficient to improve or prevent the symptoms or condition of a medical condition. An effective dose also means a dose sufficient to allow or facilitate diagnosis. The effective dose for a particular patient or veterinary subject can vary depending on factors such as the condition to be treated, the patient's overall health, the route and dosage of administration, and the severity of side effects. An effective dose can be the maximum dose or administration regimen that avoids significant side effects or toxicity.

[0100] "Exogenous" refers to substances that are produced outside of an organism, cell, or human body, depending on the context.

[0101] "Endogenous" refers to substances that are produced in cells, organisms, or the human body in accordance with their context.

[0102] "Homology" refers to the sequence similarity between two polynucleotide sequences or two polypeptides. Two compared sequences are homologous at positions occupied by the same bases or amino acid monomer subunits; for example, if every position in two DNA molecules is occupied by adenine. The percentage of homology between two sequences is a function of the number of matching or homologous positions shared by the two sequences divided by the number of positions compared, multiplied by 100%. For example, at optimal sequence alignment, if six out of ten positions in two sequences match or are homologous, then the two sequences are 60% homologous. Generally, sequences are compared when the highest percentage of homology is obtained.

[0103] The terms “cell,” “cell line,” and “cell culture” used herein are used interchangeably, and all such names include their progeny. Therefore, the words “transformation” and “transformed cell” include primary test cells and cultures derived from them, regardless of the number of transfections. It should also be understood that, due to intentional or unintentional mutations, all progeny cannot be exactly identical in terms of DNA content. This includes mutant progeny with the same function or biological activity as those screened from the original transformed cells. Where different names are used, the context will be clear.

[0104] "Optional" or "optionally" means that the event or circumstances described below may, but do not have to, occur, including the circumstances in which the event or circumstances may or may not occur. For example, "optionally contains 1-3 antibody heavy chain variable regions" means that the antibody heavy chain variable regions of a particular sequence may, but do not have to, be present.

[0105] "Pharmaceutical composition" means containing one or more antibodies or antigen-binding fragments thereof described herein, as well as other components such as physiological / pharmaceutical-grade carriers and excipients. The purpose of a pharmaceutical composition is to facilitate administration to a living organism, thereby promoting the absorption of the active ingredient and the exertment of its biological activity.

[0106] II. Implementation Examples

[0107] The following examples are used to further describe the present invention, but these examples are not intended to limit the scope of the invention. Experimental methods in the embodiments of the present invention that do not specify specific conditions are generally performed under conventional conditions, such as those described in Cold Spring Harbor's Antibody Technology Manual or Molecular Cloning Manual; or under conditions recommended by the raw material or commercial manufacturer. Reagents that do not specify a specific source are commercially available, conventional reagents.

[0108] Example 1: Screening and construction of fully human antibodies

[0109] ERBB3 antigen design:

[0110] The amino acid sequence of the human ERBB3 protein shown in SEQ ID NO:14 was used as the template for the antigen design of this invention. Unless otherwise specified, all ERBB3 antigens below refer to human ERBB3.

[0111] The full-length ERBB3 protein: The ERBB3 (SEQ ID NO: 14) sequence is as follows:

[0112]

[0113]

[0114] The ERBB3 antigen used for screening was the commercially available product Biotinylated human ERBB3-His tag (Sinobiological, cat#10201-H08H-B); the ERBB3 antigen used for detection was the commercially available product human ERBB3-His tag (Sino biological, cat#10201-H08H). The ERBB3 antigen used for detection was based on the ECD region sequence of human ERBB3, with a His tag at the C-terminus. The ERBB3 antigen used for screening was biotinylated from this sequence. The ECD sequence of human ERBB3 is as follows:

[0115]

[0116] The monkey ERBB3 antigen used for detection (SEQ ID NO: 16) is the commercially available product Rhesus ERBB3 Protein-HisTag (Sino biological, cat#90043-K08H), which is the ECD region sequence of the monkey ERBB3 antigen with a His tag added to the C-terminus. The sequence is as follows:

[0117]

[0118] PBMCs from multiple individuals were collected, B cells were isolated and RNA was extracted, reverse transcribed into cDNA, and then a natural phage surface Fab display library (1.6 × 10⁻⁶ cells / year) was constructed using the cDNA as a template. 11The constructed natural Fab phage library was packaged into phage particles and then screened using liquid chromatography. The phages were then combined with biotinylated ERBB3 solution and separated using streptavidin magnetic beads. To obtain positive sequences binding to human ERBB3, biotinylated human ERBB3 was used for 2-3 rounds of screening, and 384 monoclonal colonies were selected and packaged into phage display Fab fragments for ELISA testing. The binding activity of monoclonal phages to human ERBB3 was tested: 1 μg / mL ERBB3 was coated onto ELISA plates, phage supernatant was added, and finally, anti-human IgG Fab HRP was used for detection; the OD values ​​detected by ELISA were... 450 Eighty-six positive clones with a value greater than 0.2 were sequenced, and sequence analysis revealed 45 VH (heavy chain variable region) and 51 VL (light chain variable region) unique sequences. The obtained heavy and light chain variable region sequences were ligated to the human IgG1 heavy chain constant region and light chain constant region sequences, respectively, to obtain full-length antibodies. These full-length antibodies were experimentally evaluated, and one antibody, Ab1, with good binding affinity and function was ultimately identified. The ligated human IgG1 heavy chain constant region and light chain constant region sequences are shown in SEQ ID NO:17 and SEQ ID NO:18, respectively.

[0119] To further improve the affinity and stability of the Ab1 antibody, based on computational model predictions, the HCDR2 of the antibody was subjected to a site-directed mutation at S57E (Kabat number) to form a new HCDR2 (SEQ ID NO: 3), thereby obtaining the antibody Ab2.

[0120] Table 1. CDR sequences of heavy and light chain variable regions of antibodies

[0121]

[0122] Table 2. Heavy and light chain variable region sequences of antibodies

[0123]

[0124]

[0125] Note: The CDR area is marked with an underline.

[0126] Table 3. Heavy and light chain sequences of antibodies

[0127]

[0128] Table 4. Sequence numbers of antibodies and their heavy chain, light chain, and variable region

[0129] Antibody number HCVR HC LCVR LC Ab1 SEQ ID NO: 8 SEQ ID NO: 11 SEQ ID NO: 10 SEQ ID NO: 13 Ab2 SEQ ID NO: 9 SEQ ID NO: 12 SEQ ID NO: 10 SEQ ID NO: 13

[0130] The sequences of the IgG1 heavy chain constant region and light chain constant region are as follows:

[0131] ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQS

[0132] SGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELL

[0133] GGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPR

[0134] EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYT

[0135] LPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKL

[0136] TVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK

[0137] SEQ ID NO:17

[0138] GQPKAAPSVTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPS

[0139] KQSNNKYAASSYLSLTPEQWKSHRSYSCQVTHEGSTVEKTVAPTECS

[0140] SEQ ID NO:18

[0141] Example 2: Preparation of fully human antibodies

[0142] cDNA fragments were synthesized based on the amino acid sequences of the light and heavy chains of antibodies Ab1 and Ab2, and inserted into the pcDNA3.1 expression vector (Life Technologies Cat. No. V790-20). HEK293 cells (Life Technologies Cat. No. 11625019) were transfected with the expression vector and transfection reagent PEI (Polysciences, Inc. Cat. No. 23966) at a 1:2 ratio and incubated in a CO2 incubator for 4-5 days. The cell culture medium was collected, centrifuged, filtered, and loaded onto an antibody purification affinity column. The column was washed with phosphate buffer, eluted with glycine hydrochloride buffer (pH 2.7 0.1M Gly-HCl), neutralized with 1M Tris hydrochloric acid at pH 9.0, and dialyzed against phosphate buffer to obtain the antibody protein of this invention. Its concentration and purity are shown in Table 5.

[0143] Table 5. Antibody concentration and purity

[0144] Antibody number Concentration (mg / mL) purity(%) Ab1 0.5 97％ Ab2 0.4 95％

[0145] Example 3: In vitro binding activity of fully human antibodies

[0146] 3.1 In vitro indirect ELISA binding assay:

[0147] Human ERBB3 His protein (Sino biological, cat#10201-H08H), monkey ERBB3 His protein (Sino biological, cat#90043-K08H), mouse ERBB3 His protein (Sino biological, cat#51003-M08H), human EGFR His protein (Sino biological, cat#10001-H08H), human ERBB2 His protein (Sino biological, cat#10004-H08H), and human ERBB4 His protein (Sino biological, cat#10363-H08H) were diluted to 0.5 μg / mL with PBS at pH 7.4. The solutions were then added in 100 μL / well to 96-well high-affinity microplates and incubated overnight (16-20 hours) at 4°C. After washing the plate three times with PBST (pH 7.4 PBS containing 0.05% Tween-20), add 200 μL / well of 1% bovine serum albumin (BSA) blocking buffer diluted with PBST and incubate at 37°C for 2 hours for blocking. After blocking, discard the blocking buffer and wash the plate once with PBST buffer.

[0148] Dilute the antibody to be tested with PBST containing 1% BSA, starting at 10 nM, and serially dilute 3-fold to obtain 11 doses. Add 100 μL / well to each well of the plate and incubate at 37°C for 1 hour. After incubation, wash the plate three times with PBST, add 200 μL / well of anti-human HRP (Abcam, cat#ab97225) diluted with PBST containing 1% BSA, and incubate at 37°C for 0.5 hours. After washing the plate five times with PBST, add 100 μL / well of TMB chromogenic substrate (Suzhou Yake Chemical Reagent Co., Ltd., cat#S0025), and incubate at 25°C in the dark for 8-15 minutes. Stop the reaction by adding 50 μL / well of 1M HCl. Read the absorbance at 450 nm using a microplate reader (Thermo, Lux) and analyze the data.

[0149] The results of the concentration signal curve analysis are shown in the table below. The Ab1 antibody has good affinity for human and monkey ERBB3, but does not bind to mouse ERBB3 or other ERBB receptors (EGFR, ERBB2, ERBB3).

[0150] Table 6. Affinity of antibody to antigen protein

[0151]

[0152] Note: "+" indicates combination, "-" indicates no combination.

[0153] 3.2 In vitro cell binding experiment:

[0154] HEK293T cells overexpressing human ERBB3 (293T-human ERBB3) were digested with trypsin, centrifuged to collect cells, and then seeded into 96-well U-plates at a density adjusted with FACS buffer (1×PBS containing 2% FBS), with 1×10⁶ cells per well. 5 Up to 2×10 5 Cells were centrifuged at 1200g for 5 minutes, the supernatant was discarded, and 100 μL of antibody solution serially diluted with FACS buffer was added. The cells were incubated at 4°C for 1 hour. After centrifugation at 1200g for 5 minutes, the supernatant was discarded, and the cells were washed twice with FACS buffer. Then, 100 μL of the fluorescently labeled secondary antibody working solution (PE anti-human IgG Fc Antibody, Biolegend, Cat#409304) prepared with FACS buffer was added per well to resuspend the cells, and the cells were incubated at 4°C for 1 hour. After centrifugation at 1200g for 5 minutes, the supernatant was discarded. After washing the cells twice with FACS buffer, the cells were resuspended in PBS. The fluorescence signal was detected using a Bio-Rad (ZE5) flow cytometer, and EC5 curves were plotted to analyze the antibody-bound cells. 50 concentration.

[0155] Table 7. Binding affinity of antibodies to 293T-hERBB3 cells (EC5) 50 value)

[0156]

[0157] The results showed that the antibody of the present invention can specifically bind to cells expressing human ERBB3.

[0158] Example 4: Endocytosis of fully human antibodies

[0159] To determine whether the antibody of this invention, after binding to ERBB3, can be co-endocytosed into cells along with human ERBB3, an assessment was performed using SK-Br-3 human breast adenocarcinoma cells expressing ERBB3. Cells were digested with trypsin, collected, and resuspended in pre-chilled FACS buffer to adjust the cell concentration to 2 × 10⁻⁶ cells / year. 6 / mL. Take an EP tube, add 1mL of cell suspension, centrifuge at 1500rpm for 5 minutes and discard the supernatant. Add 1mL of the prepared antibody to resuspend the cells. The final antibody concentration is 20μg / ml. Incubate at 4℃ on a shaker for 1 hour, centrifuge and discard the supernatant (4℃, 1500rpm × 5 minutes). Wash twice with FACS buffer and discard the supernatant. Add 1mL of fluorescently labeled secondary antibody working solution PE anti-human IgG Fc Antibody (Biolegend, Cat#409304) to each tube, resuspend the cells, incubate at 4℃ on a shaker for 30 minutes, centrifuge and discard the supernatant (4℃, 1500rpm × 5 minutes). Wash twice with FACS buffer and discard the supernatant. Add 1 mL of preheated cell culture medium to each tube to resuspend the cells and mix well. Aliquot into four tubes of 250 μL each: 0 min, blank, 15 min, and 30 min groups. Place the 0 min and blank tubes on ice, and incubate the remaining tubes at 37°C for 15 min and 30 min endocytosis, respectively. At the corresponding time points, remove the EP tubes and pre-cool them on ice for 5 minutes. Centrifuge all treatment groups (4°C, 1500 rpm × 5 min) and discard the supernatant. Wash once with FACS buffer and discard the supernatant. Add 250 μL of strip buffer to the EP tubes of all treatment groups except the 0 min group, incubate at room temperature for 8 minutes, centrifuge and discard the supernatant (4°C, 1500 rpm × 5 min), wash twice with FACS buffer and discard the supernatant. Resuspend the cells in 100 μL of PBS in all treatment groups and analyze using a Bio-Rad (ZE5) flow cytometer.

[0160] Antibody endocytosis percentage (%) = (fluorescence intensity at each time point - average fluorescence intensity of the Blank group) / (average fluorescence intensity of the 0-minute group - average fluorescence intensity of the Blank group) * 100. Specific results are shown in Table 8.

[0161] Table 8. Endocytosis of fully human antibodies in tumor cells

[0162]

[0163] The results showed that the fully human antibody of this invention exhibited significant endocytosis activity in human breast adenocarcinoma cells SK-Br-3. Sequence list information: DTD Version: V1_3 Filename: 628JS195HS494PCN-1OA-Sequence List-20250701.xml Software Name: WIPO Sequence Software version: 2.3.0 Generation Date: 2025-11-13 Basic Information: Current application / Intellectual Property Office: CN Current application / application number: 202180050433.6 Current application / Application date: 2021-10-15 Current application / applicant's file name: <721122CPCN> Earliest priority application / State Intellectual Property Office: CN Earliest priority application / Application number: 202011105695.1 Earliest priority claim / Application date: 2020-10-15 Applicant's Name or Company Name: Shanghai Hansen Biomedical Technology Co., Ltd. Applicant's name or organization name / Language: zh Applicant's Name or Title / Latin Name: SHANGHAI HANSOH BIOMEDICAL CO., LTD. Inventor's Name: He Juanmei Inventor's Name / Language: zh Inventor's Name / Latin Name: HE Juanmei Invention Title: Anti-ERBB3 Antibody or its Antigen-Binding Fragment and its Pharmaceutical Uses (zh) Total sequence count: 18 sequence: Serial Number (ID): 1 Length: 5 Molecular type: AA Feature location / qualifier: - source, 1..5 > mol_type, protein > organism, Homo sapiens residues: SYAMS 5 Serial Number (ID): 2 Length: 17 Molecular type: AA Feature location / qualifier: - source, 1..17 > mol_type, protein > organism, Homo sapiens residues: AISDTGGSTY YADSVKG 17 Serial Number (ID): 3 Length: 17 Molecular type: AA Feature location / qualifier: - source, 1..17 > mol_type, protein > organism, Homo sapiens residues: AISDTGGETY YADSVKG 17 Serial Number (ID): 4 Length: 11 Molecular type: AA Feature location / qualifier: - source, 1..11 > mol_type, protein > organism, Homo sapiens residues: DLGSSDVDYF D 11 Serial Number (ID): 5 Length: 11 Molecular type: AA Feature location / qualifier: - source, 1..11 > mol_type, protein > organism, Homo sapiens residues: GGDNIGIKSV H 11 Serial Number (ID): 6 Length: 7 Molecular type: AA Feature location / qualifier: - source, 1..7 > mol_type, protein > organism, Homo sapiens residues: DDRFRPS 7 Serial Number (ID): 7 Length: 11 Molecular type: AA Feature location / qualifier: - source, 1..11 > mol_type, protein > organism, Homo sapiens residues: QVWDDTSDHP V 11 Serial Number (ID): 8 Length: 121 Molecular type: AA Feature location / qualifier: - source, 1..121 > mol_type, protein > organism, Homo sapiens residues: EVQLVESGGG LVQPGGSLRL SCAASGFTFS SYAMSWVRQA PGKGQEWVSA ISDTTGGSTYY 60 ADSVKGRFTI SRDNSKNTLY LQMNSLRAED TAVYYCAKDL GSSDVDYFDY WGQGTLVTVS 120 S 121 Serial Number (ID): 9 Length: 121 Molecular type: AA Feature location / qualifier: - source, 1..121 > mol_type, protein > organism, Homo sapiens residues: EVQLVESGGG LVQPGGSLRL SCAASGFTFS SYAMSWVRQA PGKGQEWVSA ISDTGGETYY 60 ADSVKGRFTI SRDNSKNTLY LQMNSLRAED TAVYYCAKDL GSSDVDYFDY WGQGTLVTVS 120 S 121 Serial Number (ID): 10 Length: 108 Molecular type: AA Feature location / qualifier: - source, 1..108 > mol_type, protein > organism, Homo sapiens residues: QPVLTQPPSV SVAPGQTAGV TCGGDNIGIK SVHWYQQKSA QAPLLVIYDD RFRPSGIPER 60 FSGSNSGNTA TLTISSVEVG DEADYFCQVW DDTSDHPVFG GGTGLTVL 108 Serial Number (ID): 11 Length: 451 Molecular type: AA Feature location / qualifier: - source, 1..451 > mol_type, protein > organism, Homo sapiens residues: EVQLVESGGG LVQPGGSLRL SCAASGFTFS SYAMSWVRQA PGKGQEWVSA ISDTTGGSTYY 60 ADSVKGRFTI SRDNSKNTLY LQMNSLRAED TAVYYCAKDL GSSDVDYFDY WGQGTLVTVS 120 SASTKGPSVF PLAPSSKSTS GGTAALGCLV KDYFPEPVTV SWNSGALTSG VHTFPAVLQS 180 SGLYSLSSVV TVPSSSLGTQ TYICNVNHKP SNTKVDKKVE PKSCDKTHTC PPCPAPELLG 240 GPSVFLFPPK PKDTLMISRT PEVTCVVVDV SHEDPEVKFN WYVDGVEVHN AKTKPREEQY 300 NSTYRVVSVL TVLHQDWLNG KEYKCKVSNK ALPAPIEKTI SKAKGQPREP QVYTLPPSRD 360 ELTKNQVSLT CLVKGFYPSD IAVEWESNGQ PENNYKTTPP VLDSDGSFFL YSKLTVDKSR 420 WQQGNVFSCS VMHEALHNHY TQKSLSLSPG K 451 Sequence number (ID): 12 Length: 451 Molecular type: AA Feature Location / Qualifier: - source, 1..451 > mol_type, protein > organism, Homo sapiens Residues: EVQLVESGGG LVQPGGSLRL SCAASGFTFS SYAMSWVRQA PGKGQEWVSA ISDTGGETYY 60 ADSVKGRFTI SRDNSKNTLY LQMNSLRAED TAVYYCAKDL GSSDVDYFDY WGQGTLVTVS 120 SASTKGPSVF PLAPSSKSTS GGTAALGCLV KDYFPEPVTV SWNSGALTSG VHTFPAVLQS 180 SGLYSLSSVV TVPSSSLGTQ TYICNVNHKP SNTKVDKKVE PKSCDKTHTC PPCPAPELLG 240 GPSVFLFPPK PKDTLMISRT PEVTCVVVDV SHEDPEVKFN WYVDGVEVHN AKTKPREEQY 300 NSTYRVVSVL TVLHQDWLNG KEYKCKVSNK ALPAPIEKTI SKAKGQPREP QVYTLPPSRD 360 ELTKNQVSLT CLVKGFYPSD ​​IAVEWESNGQ PENNYKTTPP VLDSDGSFFL YSKLTVDKSR 420 WQQGNVFSCS VMHEALHNHY TQKSLSLSPG K 451 Serial Number (ID): 13 Length: 214 Molecular type: AA Feature location / qualifier: - source, 1..214 > mol_type, protein > organism, Homo sapiens residues: QPVLTQPPSV SVAPGQTAGV TCGGDNIGIK SVHWYQQKSA QAPLLVIYDD RFRPSGIPER 60 FSGSNSGNTA TLTISSVEVG DEADYFCQVW DDTSDHPVFG GGTGLTVLGQ PKAAPSVTLF 120 PPSSEELQAN KATLVCLISD FYPGAVTVAW KADSSPVKAG VETTTPSKQS NNKYAASSYL 180 SLTPEQWKSH RSYSCQVTHE GSTVEKTVAP TECS 214 Serial Number (ID): 14 Length: 1342 Molecular type: AA Feature location / qualifier: - source, 1..1342 > mol_type, protein > organism, Homo sapiens remainder: MRANDALQVL GLLFSLARGS EVGNSQAVCP GTLNGLSVTG DAENQYQTLY KLYERCEVVM 60 GNLEIVLTGH NADLSFLQWI REVTGYVLVA MNEFSTLPLP NLRVVRGTQV YDGKFAIFVM 120 LNYNTNSSHA LRQLRLTQLT EILSGGVYIE KNDKLCHMDT IDWRDIVRDR DAEIVVKDNG 180 RSCPPCHEVC KGRCWGPGSE DCQTLTKTIC APQCNGHCFG PNPNQCCHDE CAGGCSGPQD 240 TDCFACRHFN DSGACVPRCP QPLVYNKLTF QLEPNPHTKY QYGGVCVASC PHNFVVDQTS 300 CVRACPPDKM EVDKNGLKMC EPCGGLCPKA CEGTGSGSRF QTVDSSNIDG FVNCTKILGN 360 LDFLITGLNG DPWHKIPALD PEKLNVFRTV REITGYLNIQ SWPPHMHNFS VFSNLTTIGG 420 RSLYNRGFSL LIMKNLNVTS LGFRSLKEIS AGRIYISANR QLCYHHSLNW TKVLRGPTEE 480 RLDIKHNRPR RDCVAEGKVC DPLCSSGGCW GPGPGQCLSC RNYSRGGVCV THCNFLNGEP 540 REFAHEAECF SCHPECQPME GTATCNGSGS DTCAQCAHFR DGPHCVSSCP HGVLGAKGPI 600 YKYPDVQNEC RPCHENCTQG CKGPELQDCL GQTLVLIGKT HLTMALTVIA GLVVIFMMLG 660 GTFLYWRGRR IQNKRAMRRY LERGESIEPL DPSEKANKVL ARIFKETELR KLKVLGSGVF 720 GTVHKGVWIP EGESIKIPVC IKVIEDKSGR QSFQAVTDHM LAIGSLDHAH IVRLLGLCPG 780 SSLQLVTQYL PLGSLLDHVR QHRGALGPQL LLNWGVQIAK GMYYLEEHGM VHRNLAARNV 840 LLKSPSQVQV ADFGVADLLP PDDKQLLYSE AKTPIKWMAL ESIHFGKYTH QSDVWSYGVT 900 VWELMTFGAE PYAGLRLAEV PDLLEKGERL AQPQICTIDV YMVMVKCWMI DENIRPTFKE 960 LANEFTRMAR DPPRYLVIKR ESGPGIAPGP EPHGLTNKKL EEVELEPELD LDLDLEAEED 1020 NLATTTLGSA LSLPVGTLNR PRGSQSLLSP SSGYMPMNQG NLGESCQESA VSGSSERCPR 1080 PVSLHPMPRG CLASESSEGH VTGSEAELQE KVSMCRSRSR SRSPRPRGDS AYHSQRHSLL 1140 TPVTPLSPPG LEEEDVNGYV MPDTHLKGTP SSREGTLSSV GLSSVLGTEE EDEDEEYEYM 1200 NRRRRHSPPH PPRPSSLEEL GYEYMDVGSD LSASLGSTQS CPLHPVPIMP TAGTTPDEDY 1260 EYMNRQRDGG GPGGDYAAMG ACPASEQGYE EMRAFQGPGH QAPHVHYARL KTLRSLEATD 1320 SAFDNPDYWH SRLFPKANAQ RT 1342 Serial number (ID): 15 Length: 643 Molecular type: AA Feature position / qualifier: - source, 1..643 > mol_type, protein > organism, Homo sapiens Residues: TRANDALQVL GLLFSLARGS EVGNSQAVCP GTLNGLSVTG DAENQYQTLY KLYERCEVVM 60 GNLEIVLTGH NADLSFLQWI REVTGYVLVA MNEFSTLPLP NLRVVRGTQV YDGKFAIFVM 120 LNYNTNSSHA LRQLRLTQLT EILSGGVYIE KNDKLCHMDT IDWRDIVRDR DAEIVVKDNG 180 RSCPPCHEVC KGRCWGPGSE DCQTLTKTIC APQCNGHCFG PNPNQCCHDE CAGGCSGPQD 240 TDCFACRHFN DSGACVPRCP QPLVYNKLTF QLEPNPHTKY QYGGVCVASC PHNFVVDQTS 300 CVRACPPDKM EVDKNGLKMC EPCGGLCPKA CEGTGSGSRF QTVDSSNIDG FVNCTKILGN 360 LDFLITGLNG DPWHKIPALD PEKLNVFRTV REITGYLNIQ SWPPHMHNFS VFSNLTTIGG 420 RSLYNRGFSL LIMKNLNVTS LGFRSLKEIS AGRIYISANR QLCYHHSLNW TKVLRGPTEE 480 RLDIKHNRPR RDCVAEGKVC DPLCSSGGCW GPGPGQCLSC RNYSRGGVCV THCNFLNGEP 540 REFAHEAECF SCHPECQPME GTATCNGSGS DTCAQCAHFR DGPHCVSSCP HGVLGAKGPI 600 YKYPDVQNEC RPCHENCTQG CKGPELQDCL GQTLVLIGKT HLT 643 Sequence number (ID): 16 Length: 643 Molecular type: AA Feature position / qualifier: ‑ source, 1..643 > mol_type, protein > organism, Macaca mulatta Residues: MRANGALQVL GLLFNLARGS EVGNSQAVCP GTLNGLSVTG DAENQYQTLY KLYERCEVVM 60 GNLEIVLTGH NADLSFLQWI REVTGYVLVA MNEFSTLPLP NLRVVRGTQV YDGKFAIFVM 120 LNYNTNSSHA LRQLRLTQLT EILSGGVYIE KNDKLCHMDT IDWKDIVRDQ DAEIVVKDNG 180 RSCPLCHEVC KGRCWGPGPE DCQTLTKTIC APQCNGHCFG PNPNQCCHDE CAGGCSGPQD 240 TDCFACRHFN DSGACVPRCP QPLVYNKLTF QLEPNPHTKY QYGGVCVASC PHNFVVDQTS 300 CVRACPPDKM EVDKNGLKMC EPCGGLCPKA CEGTGSGSRF QTVDSSNIDG FVNCTKILGN 360 LDFLITGLNG DPWHKIPALD PEKLNVFRTV REITGYLNIQ SWPPHMYNFS VFSNLTTIGG 420 RSLYNRGFSL LIMKNLNVTS LGFRSLKEIS AGRIYISANR QLCYHHSLNW TKVLRGPTEE 480 RLDIKHNRPR RDCVAEGKVC DPLCSSGGCW GPGPGQCLSC RNYSRGGVCV THCNFLNGEP 540 REFAHEAECF SCHPECQPME GTATCNGSGS DTCAQCAHFR DGPHCVSSCP HGVLGAKGPI 600 YKYPDVQNEC RPCHENCTQG CKGPELQDCL GQTLVLIGKT HLT 643 Serial Number (ID): 17 Length: 330 Molecular type: AA Feature location / qualifier: - source, 1..330 > mol_type, protein > organism, Homo sapiens residues: ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS WNSGALTSGV HTFPAVLQSS 60 GLYSLSSVVT VPSSLGTQT YICNVNHKPS NTKVDKKVEP KSCDKTHTCP PCPAPELLGG 120 PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW YVDGVEVHNA KTKPREEQYN 180 STYRVVSVLT VLHQDWLNGK EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSRDE 240 LTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV LDSDGSFFLY SKLTVDKSRW 300 QQGNVFSCSV MHEALHNHYT QKSLSLSPGK 330 Serial Number (ID): 18 Length: 106 Molecular type: AA Feature location / qualifier: - source, 1..106 > mol_type, protein > organism, Homo sapiens residual: GQPKAAPSVT LFPPSSEELQ ANKATLVCLI SDFYPGAVTV AWKADSSPVK AGVETTTPSK 60 QSNNKYAASS YLSLTPEQWK SHRSYSCQVT HEGSTVEKTV APTECS 106 END

Claims

1. An anti-ERBB3 antibody or an antigen-binding fragment thereof, comprising an antibody heavy chain variable region and an antibody light chain variable region, wherein, the antibody heavy chain variable region comprises HCDR1 set forth in SEQ ID NO: 1, HCDR2 set forth in SEQ ID NO: 2, and HCDR3 set forth in SEQ ID NO: 4; and the antibody light chain variable region comprises LCDR1 set forth in SEQ ID NO: 5, LCDR2 set forth in SEQ ID NO: 6, and LCDR3 set forth in SEQ ID NO: 7; or, the antibody heavy chain variable region comprises HCDR1 set forth in SEQ ID NO: 1, HCDR2 set forth in SEQ ID NO: 3, and HCDR3 set forth in SEQ ID NO: 4; and the antibody light chain variable region comprises LCDR1 set forth in SEQ ID NO: 5, LCDR2 set forth in SEQ ID NO: 6, and LCDR3 set forth in SEQ ID NO:

7.

2. The anti-ERBB3 antibody or an antigen-binding fragment thereof of claim 1, wherein the anti-ERBB3 antibody or an antigen-binding fragment thereof further comprises a heavy chain constant region derived from human IgGl, IgG2, IgG3, or IgG4 or a mutant thereof, and the anti-ERBB3 antibody or an antigen-binding fragment thereof further comprises a light chain constant region derived from human kappa chain, lambda chain or a mutant thereof.

3. The anti-ERBB3 antibody or an antigen-binding fragment thereof of claim 2, wherein the anti-ERBB3 antibody or an antigen-binding fragment thereof further comprises a heavy chain constant region derived from human IgGl or a variant thereof, and the anti-ERBB3 antibody or an antigen-binding fragment thereof further comprises a light chain constant region derived from human lambda chain.

4. The anti-ERBB3 antibody or an antigen-binding fragment thereof of claim 2, wherein the anti-ERBB3 antibody or an antigen-binding fragment thereof further comprises a heavy chain constant region derived from human IgGl, and the anti-ERBB3 antibody or an antigen-binding fragment thereof further comprises a light chain constant region derived from human lambda chain.

5. The anti-ERBB3 antibody or an antigen-binding fragment thereof of claim 2, wherein the anti-ERBB3 antibody or an antigen-binding fragment thereof further comprises a heavy chain constant region set forth in SEQ ID NO: 17, and the anti-ERBB3 antibody or an antigen-binding fragment thereof further comprises a light chain constant region set forth in SEQ ID NO:

18.

6. The anti-ERBB3 antibody or an antigen-binding fragment thereof of any one of claims 1-5, wherein the anti-ERBB3 antibody or an antigen-binding fragment thereof comprises a heavy chain variable region set forth in SEQ ID NO: 8, and a light chain variable region set forth in SEQ ID NO: 10; or, the anti-ERBB3 antibody or an antigen-binding fragment thereof comprises a heavy chain variable region set forth in SEQ ID NO: 9, and a light chain variable region set forth in SEQ ID NO:

10.

7. The anti-ERBB3 antibody or antigen-binding fragment thereof of claim 6, wherein, the anti-ERBB3 antibody comprises a heavy chain as set forth in SEQ ID NO: 11, and a light chain as set forth in SEQ ID NO: 13; or, the anti-ERBB3 antibody comprises a heavy chain as set forth in SEQ ID NO: 12, and a light chain as set forth in SEQ ID NO:

13.

8. A polynucleotide encoding the anti-ERBB3 antibody or antigen-binding fragment thereof of any one of claims 1-7.

9. An expression vector comprising the polynucleotide of claim 8.

10. A host cell into which or comprising the expression vector of claim 9.

11. The host cell of claim 10, wherein the host cell is a bacterium, a yeast or a mammalian cell.

12. The host cell of claim 11, wherein the bacterium is E. coli, the yeast is Pichia pastoris, the mammalian cell is a CHO cell or a HEK293 cell.

13. A method of producing an anti-ERBB3 antibody or antigen-binding fragment thereof, comprising the steps of: a) culturing the host cell of any one of claims 10-12; b) isolating the antibody from the culture; and, c) purifying the antibody.

14. A detection or diagnostic reagent comprising the anti-ERBB3 antibody or antigen-binding fragment thereof of any one of claims 1-7, and an excipient, diluent or carrier useful for detection or diagnosis.

15. Use of the anti-ERBB3 antibody or antigen-binding fragment thereof of any one of claims 1-7, or the detection or diagnostic reagent of claim 14, in the manufacture of a kit for detecting, diagnosing a cancer expressing or overexpressing ERBB3, wherein the cancer is selected from the group consisting of breast cancer, ovarian cancer, prostate cancer, lung cancer, gastric cancer, colon cancer, pancreatic cancer, melanoma.

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