CD38 monoclonal antibody and application thereof

Abstract

The invention relates to a monoclonal antibody binding to human CD38 or an antigen binding fragment thereof, the amino acid residue of the CD38 extracellular domain fragment bound by the monoclonal antibody comprises at least one selected from K25, E28, I29, M33 and R34, and the amino acid residue is numbered according to the amino acid sequence of the CD38 extracellular domain fragment as shown in SEQ ID NO: 36. The invention also relates to pharmaceutical compositions comprising these antibodies and pharmaceutical uses thereof.

Description

CD38 monoclonal antibody and its application Technical Field

[0001] The present disclosure relates to monoclonal antibodies that bind to CD38, in particular humanized monoclonal antibodies against human CD38, antigen-binding fragments thereof, and related pharmaceutical compositions and uses for treating diseases. Background Art

[0002] CD38 is a type II transmembrane glycoprotein that plays a role in regulating cell migration and receptor-mediated adhesion through interaction with CD31 or hyaluronan. CD38 also has extracellular enzymatic activity and is involved in the production of nucleotide metabolites and in controlling intracellular calcium storage.

[0003] CD38 is typically found on hematopoietic cells and is expressed at low levels in solid tissues. CD38 expression in hematopoietic cells depends on the differentiation and activation state of the cells. Under normal conditions, CD38 is expressed at relatively low levels in bone marrow and lymphocytes, as well as in some non-hematopoietic tissues. Approximately 80% of resting NK cells and monocytes express CD38 at low levels, as do various other blood cell types, including lymphoblasts in lymph node germinal centers, intrafollicular cells, dendritic cells, red blood cells, and platelets. In contrast, CD38 is also expressed on B cells, with particularly high levels expressed on normal plasma cells.

[0004] CD38 is expressed in a number of hematological malignancies, such as Waldenstrom's macroglobulinemia, primary systemic amyloidosis, mantle cell lymphoma, acute lymphoblastic leukemia, acute myeloid leukemia, NK cell leukemia, NK / T cell lymphoma, plasma cell leukemia, chronic lymphocytic leukemia (CLL), and multiple myeloma (MM). CD38 is particularly highly expressed in multiple myeloma (MM) cells, making it a target for therapeutic antibodies that target MM cell surface molecules.

[0005] In addition, there are also some reports that CD38 antibodies may also have therapeutic effects in other malignancies, such as small cell lung cancer, non-small cell lung cancer, lung bronchial epithelial carcinoma, breast cancer (derived from malignant proliferation of the epithelial lining in the mammary ducts and lobules), pancreatic tumors derived from β cells (insulinomas), tumors derived from the epithelium in the intestine (such as adenocarcinomas and squamous cell carcinomas), prostate cancer, testicular seminoma, ovarian cancer, and neuroblastoma. Many studies have also suggested the role of CD38 in autoimmunity, such as in Graves' disease and thyroiditis, type 1 and type 2 diabetes, and inflammation of airway smooth muscle cells during asthma. In addition, CD38 expression is also associated with HIV infection.

[0006] Daratumumab (hereinafter referred to as "Dara" or "DARA" or "dara") is the first CD38-targeted antibody approved as a single agent or in combination for the treatment of multiple myeloma. Sanofi's CD38 antibody, Isatuximab (hereinafter referred to as "Isa"), was recently approved by the FDA for the treatment of relapsed / refractory multiple myeloma (R / R MM). Other CD38 monoclonal antibodies undergoing clinical validation include TJ202 / MOR202 (Tianjian Biopharma / MorphoSys AG), SG301 (Shangjian Biopharma), HLX15 (Fuhong Hanlin), and TAK-079 (Takeda). Therefore, it is necessary to provide more CD38 antibodies to meet clinical needs.

[0007] Summary of the Invention

[0008] The present invention provides a monoclonal antibody or an antigen-binding fragment thereof that binds to human CD38, comprising three heavy chain complementary determining regions (HCDR1, HCDR2, and HCDR3) and three light chain complementary determining regions (LCDR1, LCDR2, and LCDR3), wherein: the amino acid sequence of HCDR1 is as shown in SEQ ID NO: 1, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of HCDR2 is as shown in SEQ ID NO: 2, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of HCDR3 is as shown in SEQ ID NO: 6, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of LCDR1 is as shown in SEQ ID NO: 7, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of LCDR2 is as shown in SEQ ID NO: 9, or a conservative substitution variant thereof of one to three amino acids; and the amino acid sequence of LCDR3 is as shown in SEQ ID NO: 11, or a conservative substitution variant thereof of one to three amino acids.

[0009] In some embodiments, the monoclonal antibody or antigen-binding fragment thereof comprises a heavy chain variable region VH and a light chain variable region VL, wherein VH comprises the amino acid sequence as shown in SEQ ID NO: 12 or SEQ ID NO: 14, or a variant thereof having at least 85% sequence identity; wherein VL comprises the amino acid sequence as shown in SEQ ID NO: 18 or SEQ ID NO: 21, or a variant thereof having at least 85% sequence identity.

[0010] In some embodiments, the monoclonal antibody or antigen-binding fragment thereof comprises a heavy chain variable region VH and a light chain variable region VL, wherein (a) the heavy chain variable region VH comprises the amino acid sequence set forth in SEQ ID NO: 12 or a variant thereof having at least 85% sequence identity thereto; the light chain variable region VL comprises the amino acid sequence set forth in SEQ ID NO: 18 or a variant thereof having at least 85% sequence identity thereto; or (b) the heavy chain variable region VH comprises the amino acid sequence set forth in SEQ ID NO: 12 or a variant thereof having at least 85% sequence identity thereto; the light chain variable region VL comprises the amino acid sequence set forth in SEQ ID NO: 21 or a variant thereof having at least 85% sequence identity thereto; or (c) the heavy chain variable region VH comprises the amino acid sequence set forth in SEQ ID NO: 14 or a variant thereof having at least 85% sequence identity thereto; the light chain variable region VL comprises the amino acid sequence set forth in SEQ ID NO: 18 or a variant thereof having at least 85% sequence identity thereto.

[0011] In some embodiments, the Fc segment of the monoclonal antibody is modified to enhance binding to FcγRIIIa(V) and / or FcγRIIIa(F). In some embodiments, the Fc segment comprises the amino acid sequence shown in SEQ ID NO: 27 or a variant thereof having at least 85% sequence identity thereto.

[0012] In some embodiments, the monoclonal antibody or antigen-binding fragment thereof comprises a heavy chain and a light chain, wherein the heavy chain comprises the amino acid sequence as shown in SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:30 or SEQ ID NO:31, or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence as shown in SEQ ID NO:34 or SEQ ID NO:35, or a variant thereof having at least 85% sequence identity.

[0013] In some embodiments, the antigen-binding fragment is selected from scFv, (scFv) 2, Fab, Fab' and F(ab') 2 of a CD38 antibody. In some embodiments, the antigen-binding fragment constitutes a part of a multispecific antibody, CAR-T or BiTE.

[0014] In some embodiments, the monoclonal antibody is of IgG type. In some embodiments, the monoclonal antibody is of IgG1, IgG2, IgG3, or IgG4 type. In some embodiments, the monoclonal antibody is of IgG1 type. In some embodiments, the monoclonal antibody or its antigen-binding fragment does not bind to healthy human red blood cells. In some embodiments, the monoclonal antibody or its antigen-binding fragment can bind to healthy human PBMC. In some embodiments, the monoclonal antibody or its antigen-binding fragment has an affinity constant Kd of 10 as determined by Biacore. -9 M level. Or its antigen-binding fragment binds to a different antigenic epitope than isatuximab. In some embodiments, the monoclonal antibody or its antigen-binding fragment binds to a different antigenic epitope than daratumumab.

[0015] In another aspect, the present disclosure provides a monoclonal antibody or an antigen-binding fragment thereof that competes with any of the above-mentioned monoclonal antibodies or antigen-binding fragments provided herein for binding to human CD38. In some embodiments, the present disclosure provides a monoclonal antibody or an antigen-binding fragment thereof that competes with FTL004-1, FTL004-6, or FTL004-7, or antigen-binding fragments thereof, provided herein for binding to human CD38.

[0016] In another aspect, the present disclosure provides a monoclonal antibody or antigen-binding fragment thereof that binds to human CD38, wherein the amino acid residues of the CD38 extracellular domain fragment to which the monoclonal antibody or antigen-binding fragment thereof binds comprise at least one selected from the group consisting of K25, E28, I29, M33, and R34, wherein the amino acid residues are numbered according to the amino acid sequence of the CD38 extracellular domain fragment as shown in SEQ ID NO: 36. In some embodiments, the amino acid residues of the CD38 extracellular domain fragment to which the monoclonal antibody or antigen-binding fragment thereof binds consist of K25, E28, I29, P31, E32, M33, R34, H35, K67, T70, Q71, T72, and V73.

[0017] In another aspect, the present invention provides a pharmaceutical composition comprising the monoclonal antibody or antigen-binding fragment thereof described in the present disclosure and a pharmaceutically acceptable carrier.

[0018] In some embodiments, the pharmaceutical composition further comprises a second therapeutic agent for treating the same cancer. In some embodiments, the second therapeutic agent is a chemotherapeutic agent, a radiotherapeutic agent, or a biologic agent. In some embodiments, the biologic agent is a monoclonal antibody, an ADC, an oncolytic virus, or a CAR-T therapy.

[0019] In another aspect, the present disclosure further provides a nucleotide sequence encoding the monoclonal antibody or antigen-binding fragment thereof of the present invention. In another aspect, the present disclosure further provides a vector comprising the aforementioned nucleotide sequence. In another aspect, the present disclosure further provides a non-human host cell comprising the aforementioned vector. Furthermore, the present invention further provides a cell line that produces the monoclonal antibody or antigen-binding fragment thereof of the present invention, a recombinant expression vector comprising the nucleotide sequence of the present invention, and a method for preparing the antibody by culturing the antibody-producing cell line.

[0020] On the other hand, the present disclosure also provides use of the monoclonal antibody or antigen-binding fragment thereof or pharmaceutical composition of the present invention in the preparation of a medicament for treating CD38-positive cancer or autoimmune disease.

[0021] In another aspect, the present invention also provides a method for treating a CD38-positive cancer or autoimmune disease in a subject, comprising administering to the subject a therapeutically effective amount of any of the monoclonal antibodies or antigen-binding fragments thereof of the present invention, or any of the pharmaceutical compositions of the present invention. In some embodiments, the method further comprises administering to the subject a second therapeutic agent, simultaneously or in any order. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1. Apoptotic activity of H2 antibody on Daudi, Ramos, Raji and SU-DHL-1 cells.

[0023] Figure 2. Elisa assay for identification of the competitive binding epitope between H2 antibody and Isa and Dara.

[0024] Figure 3. Elisa assay to detect cross-reactivity of antibodies to CD38 antigen proteins from different species.

[0025] Figure 4. Apoptosis activity test of humanized antibodies and positive controls on Ramos and Raji cells.

[0026] Figure 5. ELISA assay for the activity of humanized CD38 antibodies.

[0027] Figure 6. Tumor growth curves of humanized antibody FTL004-hu-1 / 6 / 7.

[0028] Figure 7. Tumor inhibition rate of humanized antibody FTL004-hu-1 / 6 / 7.

[0029] Figure 8. Hepatotoxicity and renal toxicity of humanized antibody FTL004-hu-1 / 6 / 7.

[0030] Figure 9. Activity changes of humanized antibodies FTL004-1 / 6 / 7 detected by ELISA.

[0031] Figure 10. Tumor growth curves of different concentrations of FTL004-1, FTL004-7, FTL004-hu-1, Isa, and FTL004-1+Dara.

[0032] Figure 11. Tumor inhibition rates of different concentrations of FTL004-1, FTL004-7, FTL004-hu-1, Isa, and FTL004-1+Dara.

[0033] Figure 12. Immunohistochemical detection of CD38 expression in tumor tissues.

[0034] Figure 13. In vivo killing effect of CD38 antibody on small cell lung cancer H211 cells.

[0035] Figure 14. Flow cytometry detection of the binding of CD38 antibodies to H211 and SU-DHL-6 cells.

[0036] Figure 15. Flow cytometry detection of the binding reaction of CD38 antibody to normal human erythrocytes.

[0037] Figure 16. Flow cytometry detection of the binding response of CD38 antibody Dara and FTL004-1 antibody to normal human PBMCs.

[0038] Figure 17. Three-dimensional structural analysis of the complex between the CD38 extracellular domain fragment and FTL004-1 Fab (CD38 / FTL004-1-Fab). (A) Overall structure of the CD38 / FTL004-1-Fab complex. The heavy and light chains of CD38 and FTL004-1 are indicated in gray, purple, and green, respectively. (B) CDRs in the CD38 / FTL004-1-Fab complex structure. (C) Amino acid sequence of the CD38 extracellular domain fragment (R45-I300). The amino acid residues binding to the FTL004-1-Fab fragment are indicated in blue. (D) 3D illustration of the direct hydrogen bonds and salt bridges between CD38 and FTL004-1. Hydrogen bonds are indicated by black dashed lines, and salt bridges are indicated by orange dashed lines. (E) Comparison of the binding of FTL004-1, daratumumab, and isatuximab. Surface representation of the epitopes of FTL004-1 (green), daratumumab (blue), isatuximab (red), and an overlay of FTL004-1 and isatuximab (yellow) on CD38 (grey). (F) Schematic representation of the proposed orientation of CD38 on the cell surface and the different epitopes of FTL004-1, daratumumab, and isatuximab. The transmembrane helix (dark gold) is proposed to be the N-terminal extension of CD38. DETAILED DESCRIPTION

[0039] definition

[0040] As used herein, the term "patient" or "subject" refers to any organism to which a provided antibody, antigen-binding fragment thereof, or pharmaceutical composition is or can be administered for experimental, diagnostic, preventive, cosmetic, and / or therapeutic purposes. Typical subjects include animals (e.g., mammals such as mice, rats, rabbits, non-human primates, and / or humans). In some embodiments, the subject is a human. In some embodiments, the subject suffers from or is susceptible to one or more disorders or conditions. The patient may exhibit one or more symptoms of a disorder or condition, or may have been diagnosed with one or more disorders or conditions (e.g., cancer / tumor). In some embodiments, the patient is receiving or has received a therapy for the diagnosis and / or treatment of such a disease, disorder, or condition.

[0041] As used herein, the term "comparable" refers to two or more agents, entities, situations, effects, condition sets, etc. that may not be identical to each other, but have sufficient similarity to allow comparisons to be made therebetween (e.g., by comparison of levels and / or activities), such that conclusions can be reasonably drawn based on the observed differences or similarities. These comparable condition sets, effects, situations, individuals, or populations are characterized by a plurality of generally consistent features and one or a few varying features. One of ordinary skill in the art will understand, in context, what degree of identity is required for two or more such agents, entities, situations, condition sets, effects, or populations, etc., to be considered comparable in any given case.

[0042] Compositions or methods described herein as "comprising" one or more recited elements or steps are open-ended, meaning that the recited elements or steps are required, but other elements or steps may be added within the scope of the composition or method. It should also be understood that any composition or method described as "comprising" one or more recited elements or steps also describes a corresponding, more limited composition or method that "consists essentially of" the recited elements or steps, meaning that the composition or method includes the recited elements or steps and may also include additional elements or steps that do not materially affect the basic and novel characteristics of the composition or method.

[0043] As used herein, the term "epitope" refers to a portion of an antigen to which an antibody or antigen-binding fragment binds. In some embodiments, an epitope may be a conformational epitope, i.e., a portion of an antigen that is not covalently adjacent but is close to each other in three-dimensional space when the antigen is in a related conformation. For example, for CD38, a conformational epitope is an epitope comprised of a plurality of non-adjacent amino acid residues contained in the extracellular domain of CD38. In some embodiments, an epitope may be a linear epitope, i.e., an epitope comprising a sequence of amino acid residues that are adjacent in the primary structure in the extracellular domain of CD38. Methods for determining the exact sequence and / or, in particular, amino acid residues of the epitope of CD38 are known in the literature and include competing with peptides from the antigen sequence for binding to CD38 sequences from different species, truncation and / or mutagenesis (e.g., by alanine scanning or other site-directed mutagenesis), phage display-based screening, or (co-) crystallography techniques. In the present invention, an amino acid residue in the extracellular domain of CD38 that binds to an antibody of the present invention is defined as a distance of 100 nm from any atom of the CDR of the antibody of the present invention. Amino acid residues within .

[0044] As used herein, amino acid residues are represented by the single-letter amino acid abbreviation followed by their position relative to a reference sequence. For example, "K25" in the phrase "amino acid residues comprise at least one selected from the group consisting of K25, E28, I29, M33, and R34, wherein the amino acid residues are numbered according to the amino acid sequence of the CD38 extracellular domain fragment as set forth in SEQ ID NO:36" refers to lysine (K) at position 25 in the sequence set forth in SEQ ID NO:36.

[0045] As used herein, the term "antibody" refers to any form of an antibody that exhibits a desired biological activity (e.g., inhibiting the binding of a ligand to its receptor or by inhibiting ligand-induced receptor signal transduction). "Antibody fragment" and "antigen-binding fragment" refer to antigen-binding fragments of antibodies and antibody analogs, which typically include at least a portion of the antigen-binding region or variable region (e.g., one or more CDRs) of the parent antibody. In some embodiments, the antibody is a monoclonal antibody. In other embodiments, the antibody is a polyclonal antibody. The term "monoclonal antibody" as used herein refers to an antibody obtained from a substantially homogeneous antibody population, i.e., the individual antibodies comprising the population are identical except for possible natural mutations that may be present in small amounts. Monoclonal antibodies are highly specific and can be directed against a single antigenic site. In addition, in contrast to conventional (polyclonal) antibody preparations that typically include multiple different antibodies directed against multiple different determinants (epitopes), each monoclonal antibody is directed against only a single determinant on the antigen. The modifier "monoclonal" indicates the characteristic of an antibody obtained from a substantially homogeneous antibody population and is not to be understood as requiring the antibody to be prepared by any particular method. For example, the monoclonal antibodies used in the present invention can be prepared by hybridoma or recombinant DNA methods. Monoclonal antibodies can include "chimeric," humanized, or fully human antibodies. In some embodiments, antibodies form part of a larger biomolecule, such as a fusion protein or antibody-drug conjugate. Antibody fragments retain at least some of the binding specificity of the parent antibody. Typically, when activity is expressed on a molar basis, antibody fragments retain at least 10% of the parent binding activity. Preferably, antibody fragments retain at least 20%, 50%, 70%, 80%, 90%, 95%, or 100% or more of the binding affinity of the parent antibody for the target.

[0046] Therefore, as used herein, examples of antibody fragments include, but are not limited to, Fab, Fab′, F(ab′)2, and Fv fragments; diabodies; linear antibodies; single-chain antibody molecules, such as sc-Fv; nanobodies; domain antibodies; and multispecific antibodies (such as bispecific antibodies), CAR-T, and BiTEs formed from antibody fragments. A "Fab fragment" consists of a light chain and the CH1 and variable regions of a heavy chain. The heavy chain of a Fab molecule cannot form a disulfide bond with another heavy chain molecule. A "Fab′ fragment" contains a light chain and a portion of a heavy chain comprising the VH domain and the CH1 domain, as well as the region between the CH1 and CH2 domains, thereby forming an interchain disulfide bond between the two heavy chains of the two Fab′ fragments to form a F(ab′)2 molecule. A "F(ab′)2 fragment" contains two light chains and two heavy chains comprising a portion of the constant region between the CH1 and CH2 domains, thereby forming an interchain disulfide bond between the two heavy chains. Therefore, a F(ab′)2 fragment consists of two Fab′ fragments held together by a disulfide bond between the two heavy chains. The "Fv region" comprises the variable regions from both the heavy and light chains, but lacks the constant regions. A "single-chain Fv antibody" (or "scFv antibody") refers to an antibody fragment that comprises the VH and VL domains of an antibody, wherein these domains are present in a single polypeptide chain. Generally speaking, the Fv polypeptide comprises an additional polypeptide linker between the VH and VL domains that enables the scFv to form the desired structure for antigen binding.

[0047] "Fc" or "Fc segment" or "Fc region" refers to a polypeptide comprising the constant region of an antibody, excluding the first constant region immunoglobulin domain and, in some cases, excluding part of the hinge. Thus, Fc refers to the last two constant region immunoglobulin domains of IgA, IgD, and IgG, the last three constant region immunoglobulin domains of IgE and IgM, and the flexible hinge N-terminal to these domains. In some embodiments, amino acid modifications are made to the Fc region, for example, to alter binding to one or more FcγR receptors or FcRn receptors.

[0048] As used herein, the term "humanized antibody" refers to an antibody comprising CDRs of an antibody derived from mammals other than humans, and framework regions (FRs) and constant regions of a human antibody.

[0049] As used herein, a sequence "variant" refers to a sequence that differs from the indicated sequence at one or more amino acid residues but retains the biological activity of the resulting molecule.

[0050] As used herein, "% identity" between two sequences refers to a function of the number of identical positions shared by the sequences (i.e., % homology = number of identical positions / total number of positions x 100), taking into account the number of gaps, and the length of each gap, that need to be introduced for optimal alignment of the two sequences. The comparison of sequences and the determination of % identity between two sequences can be accomplished using a mathematical algorithm.

[0051] A "variant having at least 85% sequence identity" refers to a sequence that is identical or substantially similar to the indicated sequence (e.g., amino acid sequence) in biological activity and function but has about 85%, about 90%, about 95%, about 96%, about 97%, about 98% or about 99% sequence identity with the indicated sequence.

[0052] "Conservative substitutions" refer to amino acid substitutions known to those skilled in the art that are made without generally altering the biological activity of the resulting molecule. In general, it is recognized by those skilled in the art that single amino acid substitutions in non-essential regions of a polypeptide do not substantially alter or substantially change the biological activity. "No alteration or no substantial alteration" means that one or more aspects of the polypeptide differ by no more than about 20%, about 15%, about 10%, about 9%, about 8%, about 7%, about 6%, about 5%, about 4%, about 3%, about 2%, or about 1% when compared to the subject being compared, when measured by the same or similar method.

[0053] "One to three amino acid conservative substitution variants" means that compared to the sequence shown, the variant has one to three (e.g., one to two, two to three, one, two or three, identical or different) amino acid substitutions known to those skilled in the art, and that performing such substitutions generally does not change or substantially change the biological activity of the resulting molecule. When each CDR may be replaced by one to three amino acid conservative substitution variants, each CDR is independently replaced by one to three amino acid conservative substitutions. For example, LCDR2 is replaced by one amino acid conservative substitution variant, HCDR2 may be replaced by two amino acid conservative substitution variants, and HCDR1 and LCDR3 may not be replaced at all. When multiple CDRs are involved in conservative substitutions, all substitutions generally do not change or substantially change the biological activity of the antibody molecule. Generally, HCDR3 and LCDR3 are considered to play a more important role in antigen recognition than other CDRs. Therefore, in the case of substitutions, the present disclosure preferably performs conservative substitutions on CDRs other than HCDR3 and LCDR3. In some embodiments, HCDR1, HCDR3 and LCDR3 are not replaced. Preferred amino acid substitutions include, but are not limited to, substitutions that (1) reduce susceptibility to proteolysis, (2) reduce susceptibility to oxidation, (3) alter binding affinity for forming protein complexes, and (4) provide or modify other physicochemical or functional properties of these analogs. Analogs may include mutations of various sequences other than the naturally occurring peptide sequence. For example, single or multiple amino acid substitutions (preferably conservative amino acid substitutions) may be made in the naturally occurring sequence (preferably in the portion of the polypeptide outside the region forming intermolecular contacts). Conservative amino acid substitutions should not substantially alter the structural characteristics of the parent sequence (e.g., amino acid substitutions should not tend to disrupt helices present in the parent sequence, or characterize disruption of other secondary structural types of the parent sequence).

[0054] It is anticipated that the binding domain of the monoclonal antibody or antigen-binding fragment thereof of the present invention may contain a signal peptide, which is typically located at the N-terminus of the secretory protein and generally consists of 15 to 30 amino acids. After the signal peptide sequence is synthesized, it is recognized by the signal recognition particle (SRP), causing protein synthesis to pause or slow down. The signal recognition particle then carries the ribosome to the endoplasmic reticulum, where protein synthesis resumes. Guided by the signal peptide, the newly synthesized protein enters the endoplasmic reticulum lumen, while the signal peptide sequence is removed by the action of a signal peptidase. If a termination transport sequence is present at the C-terminus of the nascent peptide chain, it may not be removed by a signal peptidase, such as ovalbumin, which contains an internal signal peptide. Neither its precursor nor its mature form undergoes the process of being removed by a signal peptidase.

[0055] When referring to a ligand / receptor, antibody / antigen, or other binding pair, "specific" binding refers to the determination of the presence or absence of a binding reaction for a protein in a heterogeneous population of proteins and / or other biological agents. Thus, under specified conditions, a specific ligand / antigen binds to a specific receptor / antibody and does not bind to other proteins present in the sample in significant amounts. "Specific binding" means that the monoclonal antibody of the present invention, or its antigen-binding fragment, is able to specifically interact with at least two, three, four, five, six, seven, eight, or more amino acids of a respective target molecule. The "specific binding" of an antibody is primarily characterized by two parameters: a qualitative parameter (binding epitope or antibody binding site) and a quantitative parameter (binding affinity or binding strength). Antibody binding epitopes can be determined by FACS, peptide spot epitope mapping, mass spectrometry, or peptide ELISA. Biacore and / or ELISA methods can determine the binding strength of an antibody to a specific epitope. The signal-to-noise ratio is often used as a representative measurement and calculation method for binding specificity. In such a signal-to-noise ratio, the signal represents the strength of antibody binding to the target epitope, while the noise represents the strength of antibody binding to other non-target epitopes. Preferably, an antibody being evaluated can be considered to bind to the target epitope in a specific manner, i.e., "specifically bind", when the signal-to-noise ratio for the target epitope is about 50. An antigen binding protein (including an antibody) "specifically binds" to an antigen if it binds to the antigen with a high binding affinity as determined by an affinity constant (KD) value. In some embodiments, the affinity constant KD is less than 10 -9 M. As used herein, the term "KD" refers to the affinity constant for a specific antibody-antigen interaction.

[0056] In the present invention, "about" means that a value is within an acceptable error range for the specific value determined by one of ordinary skill in the art, which value depends in part on how the measurement or determination is made (i.e., the limitations of the measurement system). For example, "about" can mean within 1 or more than 1 standard deviation per practice in the art. Alternatively, "about" or "substantially comprising" can mean a range of up to 20%. In addition, particularly with respect to biological systems or processes, the term can mean up to an order of magnitude or up to 5 times the value. Unless otherwise indicated, when a specific value appears in the application and claims, the meaning of "about" or "substantially comprising" should be assumed to be within an acceptable error range for that specific value.

[0057] "Administering" and "treating," when used in reference to an animal, human, subject, cell, tissue, organ, or biological fluid, refers to contacting an exogenous drug, therapeutic agent, diagnostic agent, or composition with the animal, human, subject, cell, tissue, organ, or biological fluid. "Administering" and "treating" can refer to, for example, therapeutic methods, pharmacokinetic methods, diagnostic methods, research methods, and experimental methods. Treating cells includes contacting an agent with a cell and contacting an agent with a fluid, wherein the fluid is contacted with the cell. "Administering" and "treating" also mean the in vitro and ex vivo treatment of cells, for example, by an agent, diagnostic agent, binding composition, or by other cells.

[0058] As used herein, the terms "inhibit" or "treat" include delaying the development of symptoms associated with a disease and / or lessening the severity of symptoms that will or are expected to develop. The terms also encompass alleviating existing symptoms, preventing additional symptoms, and alleviating or preventing the underlying causes of the symptoms. Thus, the terms indicate that a beneficial outcome has been conferred on a vertebrate subject suffering from a disease.

[0059] As used herein, the term "therapeutically effective amount" or "effective amount" refers to an amount of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 of the present invention, when administered alone or in combination with another therapeutic agent to a cell, tissue, or subject, that is effective in preventing or alleviating the disease or condition being treated. A therapeutically effective dose further refers to an amount of the compound sufficient to cause a reduction in symptoms, such as treatment, cure, prevention, or alleviation of the relevant medical condition, or to increase the rate of treatment, cure, prevention, or alleviation of the symptoms. When administered to an individual, the therapeutically effective amount refers to that individual ingredient. When administered in combination, the therapeutically effective amount refers to the combined amount of the active ingredients that produces the therapeutic effect, regardless of whether they are administered in combination, sequentially, or simultaneously. A therapeutically effective amount will generally reduce symptoms by at least 10%; typically at least 20%; preferably at least about 30%; more preferably at least 40% and most preferably at least 50%.

[0060] The terms "cancer," "malignant disease," "tumor," "tumor," and "cancer" are used interchangeably herein to refer to cells that exhibit relatively abnormal, uncontrolled, and / or autonomous growth, such that they exhibit an abnormal growth phenotype characterized by significantly uncontrolled cell proliferation. Generally, cells of interest for detection or treatment in the present application include precancerous (e.g., benign), malignant, premetastatic, metastatic, and non-metastatic cells. The cancer of the present invention may be associated with any cancer that expresses CD38.

[0061] As used herein, the term "pharmaceutically acceptable" as applied to a carrier, diluent or excipient for formulating a composition as disclosed herein means that the carrier, diluent or excipient must be compatible with the other ingredients of the composition and not deleterious to the recipient thereof.

[0062] Anti-CD38 monoclonal antibody

[0063] In one aspect of the present invention, a monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises three heavy chain complementary determining regions HCDR1, HCDR2, and HCDR3, and three light chain complementary determining regions LCDR1, LCDR2, and LCDR3, wherein: the amino acid sequence of HCDR1 is as shown in SEQ ID NO: 1, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of HCDR2 is as shown in SEQ ID NO: 2, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of HCDR3 is as shown in SEQ ID NO: 6, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of LCDR1 is as shown in SEQ ID NO: 7, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of LCDR2 is as shown in SEQ ID NO: 9, or a conservative substitution variant thereof of one to three amino acids; and the amino acid sequence of LCDR3 is as shown in SEQ ID NO: 11, or a conservative substitution variant thereof of one to three amino acids.

[0064] In one aspect of the present invention, a monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises three heavy chain complementary determining regions HCDR1, HCDR2, and HCDR3, and three light chain complementary determining regions LCDR1, LCDR2, and LCDR3, wherein: the amino acid sequence of HCDR1 is as shown in SEQ ID NO: 1, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of HCDR2 is as shown in SEQ ID NO: 2, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of HCDR3 is as shown in SEQ ID NO: 6; the amino acid sequence of LCDR1 is as shown in SEQ ID NO: 7, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of LCDR2 is as shown in SEQ ID NO: 9, or a conservative substitution variant thereof of one to three amino acids; and the amino acid sequence of LCDR3 is as shown in SEQ ID NO: 11.

[0065] In one aspect of the present invention, a monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises three heavy chain complementary determining regions HCDR1, HCDR2, and HCDR3, and three light chain complementary determining regions LCDR1, LCDR2, and LCDR3, wherein: the amino acid sequence of HCDR1 is as shown in SEQ ID NO: 1; the amino acid sequence of HCDR2 is as shown in SEQ ID NO: 2, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of HCDR3 is as shown in SEQ ID NO: 6; the amino acid sequence of LCDR1 is as shown in SEQ ID NO: 7, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of LCDR2 is as shown in SEQ ID NO: 9, or a conservative substitution variant thereof of one to three amino acids; and the amino acid sequence of LCDR3 is as shown in SEQ ID NO: 11.

[0066] In some embodiments, the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises three heavy chain complementary determining regions HCDR1, HCDR2, and HCDR3 and three light chain complementary determining regions LCDR1, LCDR2, and LCDR3, wherein: the amino acid sequence of HCDR1 is shown in SEQ ID NO:1; the amino acid sequence of HCDR2 is shown in SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, or SEQ ID NO:5; the amino acid sequence of HCDR3 is shown in SEQ ID NO:6; the amino acid sequence of LCDR1 is shown in SEQ ID NO:7 or SEQ ID NO:8; the amino acid sequence of LCDR2 is shown in SEQ ID NO:9 or SEQ ID NO:10; and the amino acid sequence of LCDR3 is shown in SEQ ID NO:11.

[0067] In some embodiments, the complementarity determining regions of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprise: HCDR1, whose amino acid sequence is shown in SEQ ID NO: 1; HCDR2, whose amino acid sequence is shown in SEQ ID NO: 2; HCDR3, whose amino acid sequence is shown in SEQ ID NO: 6; LCDR1, whose amino acid sequence is shown in SEQ ID NO: 7; LCDR2, whose amino acid sequence is shown in SEQ ID NO: 9; and LCDR3, whose amino acid sequence is shown in SEQ ID NO: 11.

[0068] In some embodiments, the complementarity determining regions of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprise: HCDR1, whose amino acid sequence is shown in SEQ ID NO: 1; HCDR2, whose amino acid sequence is shown in SEQ ID NO: 3; HCDR3, whose amino acid sequence is shown in SEQ ID NO: 6; LCDR1, whose amino acid sequence is shown in SEQ ID NO: 7; LCDR2, whose amino acid sequence is shown in SEQ ID NO: 9; and LCDR3, whose amino acid sequence is shown in SEQ ID NO: 11.

[0069] In some embodiments, the complementarity determining regions of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprise: HCDR1, whose amino acid sequence is shown in SEQ ID NO: 1; HCDR2, whose amino acid sequence is shown in SEQ ID NO: 2; HCDR3, whose amino acid sequence is shown in SEQ ID NO: 6; LCDR1, whose amino acid sequence is shown in SEQ ID NO: 8; LCDR2, whose amino acid sequence is shown in SEQ ID NO: 10; and LCDR3, whose amino acid sequence is shown in SEQ ID NO: 11.

[0070] In some embodiments, the complementarity determining regions of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprise: HCDR1, whose amino acid sequence is shown in SEQ ID NO: 1; HCDR2, whose amino acid sequence is shown in SEQ ID NO: 4; HCDR3, whose amino acid sequence is shown in SEQ ID NO: 6; LCDR1, whose amino acid sequence is shown in SEQ ID NO: 7; LCDR2, whose amino acid sequence is shown in SEQ ID NO: 9; and LCDR3, whose amino acid sequence is shown in SEQ ID NO: 11.

[0071] In some embodiments, the complementarity determining regions of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprise: HCDR1, whose amino acid sequence is shown in SEQ ID NO: 1; HCDR2, whose amino acid sequence is shown in SEQ ID NO: 5; HCDR3, whose amino acid sequence is shown in SEQ ID NO: 6; LCDR1, whose amino acid sequence is shown in SEQ ID NO: 7; LCDR2, whose amino acid sequence is shown in SEQ ID NO: 9; and LCDR3, whose amino acid sequence is shown in SEQ ID NO: 11.

[0072] In any of the above embodiments, any of the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are obtained according to the Kabat definition scheme.

[0073] In another aspect of the present invention, the present disclosure provides a monoclonal antibody or antigen-binding fragment thereof that binds to human CD38, comprising a heavy chain variable region (VH) and a light chain variable region (VL), wherein the heavy chain variable region (VH) comprises HCDR1, HCDR2, and HCDR3, and the light chain variable region (VL) comprises LCDR1, LCDR2, and LCDR3, and the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 are respectively the same as the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 selected from any one of the following groups:

[0074] (a) HCDR1, HCDR2 and HCDR3 of the heavy chain variable region having an amino acid sequence as shown in SEQ ID NO: 12, and LCDR1, LCDR2 and LCDR3 of the light chain variable region having an amino acid sequence as shown in any one of SEQ ID NOs: 18, 19, 20 and 21;

[0075] (b) the amino acid sequences of HCDR1, HCDR2, and HCDR3 of the heavy chain variable region as shown in SEQ ID NO: 13, and the amino acid sequences of LCDR1, LCDR2, and LCDR3 of the light chain variable region as shown in SEQ ID NO: 18 or 19;

[0076] (c) the amino acid sequences of HCDR1, HCDR2, and HCDR3 of the heavy chain variable region as shown in SEQ ID NO: 14, and the amino acid sequences of LCDR1, LCDR2, and LCDR3 of the light chain variable region as shown in any one of SEQ ID NOs: 18, 20, and 21;

[0077] (d) the amino acid sequences of HCDR1, HCDR2, and HCDR3 of the heavy chain variable region set forth in SEQ ID NO: 15, and the amino acid sequences of LCDR1, LCDR2, and LCDR3 of the light chain variable region set forth in SEQ ID NO: 18;

[0078] (e) the amino acid sequences of HCDR1, HCDR2, and HCDR3 of the heavy chain variable region as shown in SEQ ID NO: 16, and the amino acid sequences of LCDR1, LCDR2, and LCDR3 of the light chain variable region as shown in any one of SEQ ID NOs: 18, 19, 20, and 21;

[0079] (f) HCDR1, HCDR2 and HCDR3 of the heavy chain variable region as shown in SEQ ID NO: 17, and LCDR1, LCDR2 and LCDR3 of the light chain variable region as shown in SEQ ID NO: 18 or 19; and

[0080] (g) the amino acid sequences of HCDR1, HCDR2 and HCDR3 of the heavy chain variable region shown in SEQ ID NO: 23, and the amino acid sequences of LCDR1, LCDR2 and LCDR3 of the light chain variable region shown in SEQ ID NO: 24.

[0081] In another aspect of the invention described above, each group of CDRs is defined according to any one of the Kabat, Chothia, IMGT, Contact, and AbM definition schemes. In a preferred embodiment of this aspect, each group of CDRs is defined according to any one of the Chothia, IMGT, Contact, and AbM definition schemes. In a preferred embodiment of this aspect, each group of CDRs is defined according to the Kabat definition scheme. In a preferred embodiment of this aspect, each group of CDRs is defined according to the Chothia definition scheme. In a preferred embodiment of this aspect, each group of CDRs is defined according to the IMGT definition scheme. In a preferred embodiment of this aspect, each group of CDRs is defined according to the Contact definition scheme. In a preferred embodiment of this aspect, each group of CDRs is defined according to the AbM definition scheme.

[0082] In another aspect of the invention, the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 of the invention comprises: (1) a VH comprising an amino acid sequence selected from SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16 or SEQ ID NO: 17, or a variant thereof having at least 85% sequence identity; and (2) a VL comprising an amino acid sequence selected from SEQ ID NO: 18, SEQ ID NO: 19, SEQ ID NO: 20 or SEQ ID NO: 21, or a variant thereof having at least 85% sequence identity.

[0083] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence as shown in SEQ ID NO: 12 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence as shown in SEQ ID NO: 18 or a variant thereof having at least 85% sequence identity.

[0084] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence as shown in SEQ ID NO: 13 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence as shown in SEQ ID NO: 18 or a variant thereof having at least 85% sequence identity.

[0085] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence shown in SEQ ID NO: 12 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence shown in SEQ ID NO: 19 or a variant thereof having at least 85% sequence identity.

[0086] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence shown in SEQ ID NO: 13 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence shown in SEQ ID NO: 19 or a variant thereof having at least 85% sequence identity.

[0087] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence as shown in SEQ ID NO: 12 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence as shown in SEQ ID NO: 20 or a variant thereof having at least 85% sequence identity.

[0088] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence shown in SEQ ID NO: 12 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence shown in SEQ ID NO: 21 or a variant thereof having at least 85% sequence identity.

[0089] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence as shown in SEQ ID NO: 14 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence as shown in SEQ ID NO: 18 or a variant thereof having at least 85% sequence identity.

[0090] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence as shown in SEQ ID NO: 15 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence as shown in SEQ ID NO: 18 or a variant thereof having at least 85% sequence identity.

[0091] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence shown in SEQ ID NO: 14 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence shown in SEQ ID NO: 19 or a variant thereof having at least 85% sequence identity.

[0092] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence as shown in SEQ ID NO: 15 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence as shown in SEQ ID NO: 19 or a variant thereof having at least 85% sequence identity.

[0093] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence as shown in SEQ ID NO: 14 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence as shown in SEQ ID NO: 20 or a variant thereof having at least 85% sequence identity.

[0094] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence as shown in SEQ ID NO: 14 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence as shown in SEQ ID NO: 21 or a variant thereof having at least 85% sequence identity.

[0095] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence as shown in SEQ ID NO: 16 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence as shown in SEQ ID NO: 18 or a variant thereof having at least 85% sequence identity.

[0096] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence as shown in SEQ ID NO: 17 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence as shown in SEQ ID NO: 18 or a variant thereof having at least 85% sequence identity.

[0097] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence as shown in SEQ ID NO: 16 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence as shown in SEQ ID NO: 19 or a variant thereof having at least 85% sequence identity.

[0098] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence as shown in SEQ ID NO: 17 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence as shown in SEQ ID NO: 19 or a variant thereof having at least 85% sequence identity.

[0099] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence as shown in SEQ ID NO: 16 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence as shown in SEQ ID NO: 20 or a variant thereof having at least 85% sequence identity.

[0100] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence as shown in SEQ ID NO: 16 or a variant thereof having at least 85% sequence identity thereto; and a VL comprising the amino acid sequence as shown in SEQ ID NO: 21 or a variant thereof having at least 85% sequence identity thereto.

[0101] In some embodiments, the variable region of the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a VH comprising the amino acid sequence as shown in SEQ ID NO: 23 or a variant thereof having at least 85% sequence identity; and a VL comprising the amino acid sequence as shown in SEQ ID NO: 24 or a variant thereof having at least 85% sequence identity.

[0102] In some embodiments, the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises a heavy chain constant region and a light chain constant region, wherein the heavy chain constant region comprises the amino acid sequence shown in SEQ ID NO: 25, and the light chain constant region comprises the amino acid sequence shown in SEQ ID NO: 33.

[0103] In some embodiments, the Fc segment of any of the above-described monoclonal antibodies is modified to enhance binding to FcγRIIIa(V) and / or FcγRIIIa(F). In some embodiments, the Fc segment of the monoclonal antibody comprises the amino acid sequence shown in SEQ ID NO: 27 or a variant thereof having at least 85% sequence identity thereto.

[0104] In another aspect of the invention, the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: (1) a heavy chain comprising the amino acid sequence of SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:30 or SEQ ID NO:31, or a variant thereof having at least 85% sequence identity; and (2) a light chain comprising the amino acid sequence of SEQ ID NO:34 or SEQ ID NO:35, or a variant thereof having at least 85% sequence identity.

[0105] In some embodiments, the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a heavy chain comprising the amino acid sequence as shown in SEQ ID NO:28 or a variant thereof having at least 85% sequence identity; and a light chain comprising the amino acid sequence as shown in SEQ ID NO:34 or a variant thereof having at least 85% sequence identity.

[0106] In some embodiments, the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a heavy chain comprising the amino acid sequence as shown in SEQ ID NO:28 or a variant thereof having at least 85% sequence identity; and a light chain comprising the amino acid sequence as shown in SEQ ID NO:35 or a variant thereof having at least 85% sequence identity.

[0107] In some embodiments, the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a heavy chain comprising the amino acid sequence shown in SEQ ID NO:29 or a variant thereof having at least 85% sequence identity; and a light chain comprising the amino acid sequence shown in SEQ ID NO:34 or a variant thereof having at least 85% sequence identity.

[0108] In some embodiments, the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a heavy chain comprising the amino acid sequence as shown in SEQ ID NO:30 or a variant thereof having at least 85% sequence identity; and a light chain comprising the amino acid sequence as shown in SEQ ID NO:34 or a variant thereof having at least 85% sequence identity.

[0109] In some embodiments, the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a heavy chain comprising the amino acid sequence as shown in SEQ ID NO:30 or a variant thereof having at least 85% sequence identity; and a light chain comprising the amino acid sequence as shown in SEQ ID NO:35 or a variant thereof having at least 85% sequence identity.

[0110] In some embodiments, the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprises: a heavy chain comprising the amino acid sequence shown in SEQ ID NO:31 or a variant thereof having at least 85% sequence identity; and a light chain comprising the amino acid sequence shown in SEQ ID NO:34 or a variant thereof having at least 85% sequence identity.

[0111] In some embodiments, the monoclonal antibody is of IgG type. In some embodiments, the monoclonal antibody is of IgG1 type.

[0112] In some embodiments, the monoclonal antibody or antigen-binding fragment thereof does not bind to healthy human red blood cells. In some embodiments, the monoclonal antibody or antigen-binding fragment thereof can bind to healthy human PBMCs. In some embodiments, the monoclonal antibody or antigen-binding fragment thereof does not bind to healthy human red blood cells and can bind to healthy human PBMCs. In some embodiments, the present disclosure provides a monoclonal antibody or antigen-binding fragment thereof that binds to SEQ ID NO: 22 but does not bind to healthy human red blood cells. In some embodiments, the present disclosure provides a monoclonal antibody or antigen-binding fragment thereof that binds to SEQ ID NO: 22 but does not bind to healthy human red blood cells and competes with any of the monoclonal antibodies or antigen-binding fragments provided herein for binding to human CD38. In some embodiments, the present disclosure provides a monoclonal antibody or antigen-binding fragment thereof that binds to SEQ ID NO: 22 but does not bind to healthy human red blood cells and competes with FTL004-1, FTL004-6, or FTL004-7 for binding to human CD38. In some embodiments, the present disclosure provides a monoclonal antibody or an antigen-binding fragment thereof that binds to SEQ ID NO: 22 but does not bind to healthy human erythrocytes and competes with FTL004-1 for binding to human CD38.

[0113] In some embodiments, the monoclonal antibody or antigen-binding fragment thereof has an affinity constant Kd of 10 -9 In some embodiments, the affinity constant Kd of the monoclonal antibody or antigen-binding fragment thereof as determined by Biacore is 1.42x10 -9 M to 2.78x10 -9 M.

[0114] In some embodiments, the monoclonal antibody or antigen-binding fragment thereof binds to SEQ ID NO: 22. In some embodiments, the monoclonal antibody or antigen-binding fragment thereof binds to a different antigenic epitope than Isatuximab. In some embodiments, the monoclonal antibody or antigen-binding fragment thereof binds to a different antigenic epitope than Daratumumab. In some embodiments, the monoclonal antibody or antigen-binding fragment thereof binds to a different antigenic epitope than Isatuximab and Daratumumab. In some embodiments, the present disclosure provides a monoclonal antibody or antigen-binding fragment thereof that binds to SEQ ID NO: 22 and binds to a different antigenic epitope than Isatuximab and Daratumumab. In some embodiments, the present disclosure provides a monoclonal antibody or antigen-binding fragment thereof that binds to SEQ ID NO: 22, binds to a different antigenic epitope than Isatuximab and Daratumumab, and does not bind to healthy human red blood cells.

[0115] In some embodiments, the present disclosure provides a monoclonal antibody or an antigen-binding fragment thereof that competes with any of the monoclonal antibodies or antigen-binding fragments provided herein for binding to human CD38. In some embodiments, the monoclonal antibodies or antigen-binding fragments thereof provided herein compete for binding to human CD38 with any one of the antibodies selected from: H2, FTL004-hu-1, FTL004-hu-2, FTL004-hu-3, FTL004-hu-4, FTL004-hu-5, FTL004-hu-6, FTL004-hu-7, FTL004-hu-8, FTL004-hu-9, FTL004-hu-10, FTL004-hu-11, FTL004-hu-12, FTL004-hu-13, FTL004-hu-14, FTL004-hu-15, FTL004-hu-16, FTL004-hu-17, FTL004-hu-18, FTL004-1, FTL004-6, and FTL004-7. In some embodiments, the monoclonal antibodies or antigen-binding fragments thereof provided herein compete with FTL004-1, FTL004-6, or FTL004-7 for binding to human CD38. In some embodiments, the monoclonal antibodies or antigen-binding fragments thereof provided herein compete with FTL004-1 for binding to human CD38.

[0116] In some embodiments, the present disclosure provides a monoclonal antibody or an antigen-binding fragment thereof that binds to SEQ ID NO: 22, binds to a different antigenic epitope than Isatuximab and Daratumumab, but does not bind to healthy human red blood cells, and competes with any of the monoclonal antibodies or antigen-binding fragments provided herein for binding to human CD38.

[0117] In some embodiments, the present disclosure provides a monoclonal antibody or an antigen-binding fragment thereof that binds to SEQ ID NO: 22, binds to a different antigenic epitope than Isatuximab and Daratumumab, but does not bind to healthy human red blood cells, and competes with FTL004-1, FTL004-6, or FTL004-7 for binding to human CD38.

[0118] In some embodiments, the present disclosure provides a monoclonal antibody or an antigen-binding fragment thereof that binds to SEQ ID NO: 22, binds to a different antigenic epitope than Isatuximab and Daratumumab, but does not bind to healthy human red blood cells, and competes with FTL004-1 for binding to human CD38.

[0119] In another aspect of the present invention, a monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 is provided, wherein the amino acid residues of the CD38 extracellular domain fragment to which it binds comprise at least one selected from K25, E28, I29, M33, and R34, wherein the amino acid residues are numbered according to the amino acid sequence of the CD38 extracellular domain fragment as shown in SEQ ID NO: 36. In some embodiments, the amino acid residues of the CD38 extracellular domain fragment to which the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 comprise K25, E28, I29, M33, and R34. In some embodiments, the amino acid residues of the CD38 extracellular domain fragment to which the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 further comprise at least one selected from P31, E32, H35, K67, T70, Q71, T72, and V73. In some embodiments, the amino acid residues of the CD38 extracellular domain fragment bound by the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 further comprise P31, E32, H35, K67, T70, Q71, T72, and V73. In some embodiments, the amino acid residues of the CD38 extracellular domain fragment bound by the monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 consist of K25, E28, I29, P31, E32, M33, R34, H35, K67, T70, Q71, T72, and V73. In some embodiments, the antigen-binding fragment is selected from Fv, scFv, (scFv)2, Fab, Fab', and F(ab')2. In some embodiments, the monoclonal antibody or antigen-binding fragment thereof does not bind to healthy human red blood cells.

[0120] When using recombinant technology, the antibody can be produced in the cell, periplasmic space or directly secreted into the culture medium. If the antibody is produced in the cell, then as a first step, for example, by centrifugal or ultrafiltration to remove particle debris (host cell or cracked fragment). When the antibody is secreted into the culture medium, usually first with commercially available protein concentration filter (for example Amicon or Millipore Pellicon ultrafiltration unit) concentrated supernatant from the expression system. Can use protease inhibitors (for example PMSF) to inhibit proteolysis in any of the aforementioned steps, can use antibiotics to prevent the growth of foreign contaminants.

[0121] Depending on the antibody to be recovered, other protein purification techniques may also be utilized, such as fractionation on an ion exchange column, ethanol precipitation, reverse phase HPLC, silica gel chromatography, chromatography on anion or cation exchange resins (e.g., polyaspartic acid columns), chromatofocusing, SDS-PAGE, and ammonium sulfate precipitation. In one embodiment, glycoproteins may be purified by adsorbing the glycoproteins onto a lectin substrate (e.g., a lectin affinity column) to remove fucose-containing glycoproteins from the preparation and thereby enrich for fucose-free glycoproteins.

[0122] To express the heavy and / or light chains of the monoclonal antibodies or antigen-binding fragments thereof described herein, the polynucleotides encoding the heavy and / or light chains are inserted into expression vectors so that the genes are operably linked to transcription and translation sequences. An expression vector is any vector that a person skilled in the art would know how to conveniently ensure expression of the heavy and / or light chains. In some embodiments, the vector is a viral vector or a non-viral vector. In some embodiments, the non-viral vector is selected from the group consisting of: a plasmid, a liposome, a retroviral element, a transposon, and an exosome. In some embodiments, the viral vector is selected from the group consisting of: a retrovirus, an adenovirus, an adeno-associated virus, herpes simplex virus, a vaccinia virus, a baculovirus, and a lentivirus. A person skilled in the art will appreciate that the polynucleotides encoding the heavy and light chains can be cloned into different vectors, or into the same vector. In a preferred embodiment, the polynucleotides are cloned into the same vector.

[0123] Therefore, the present disclosure also provides nucleotide sequences encoding the monoclonal antibodies or antigen-binding fragments thereof described herein. In one embodiment, the nucleotide sequence encodes the heavy chain and / or light chain of the monoclonal antibody or antigen-binding fragment thereof described herein. In a preferred embodiment, a single nucleic acid sequence encodes the heavy chain of the monoclonal antibody or antigen-binding fragment thereof described herein, and a separate nucleic acid sequence encodes the light chain of the monoclonal antibody or antigen-binding fragment thereof described herein.

[0124] Another aspect of the present invention provides a polynucleotide encoding a polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NO: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, and 35. In a preferred embodiment, the polypeptide encoded by the polynucleotide of the present invention is selected from the group consisting of SEQ ID NO: 1, 2, 6, 7, 8, 9, 10, 11, 12, 14, 18, 21, 23, 24, 25, 26, 27, 28, 29, 30, 31, 33, 34, and 35. The present invention is not limited to the polynucleotides themselves, but also includes all polynucleotides that show at least 80% identity to the polynucleotides.

[0125] The present invention provides vectors containing the nucleotide sequences of the present invention. In one embodiment, the vector contains nucleotides encoding the monoclonal antibodies or antigen-binding fragments thereof described herein. In another embodiment, the nucleotides encode the heavy chains of the monoclonal antibodies or antigen-binding fragments thereof described herein. In another embodiment, the nucleotides encode the light chains of the monoclonal antibodies or antigen-binding fragments thereof described herein. The present invention also provides vectors containing polynucleotide molecules encoding fusion proteins, modified antibodies, antibody fragments, and probes thereof.

[0126] The polynucleotides of the present invention and vectors containing these molecules can be used to transform appropriate mammalian host cells. Transformation can be performed by any known method for introducing polynucleotides into cellular hosts known to those skilled in the art.

[0127] Pharmaceutical composition

[0128] Another aspect of the present invention provides a pharmaceutical composition comprising any one of the monoclonal antibodies or antigen-binding fragments thereof disclosed above, and a pharmaceutically acceptable carrier.

[0129] "Pharmaceutical composition" refers to a pharmaceutical formulation for use in humans. The pharmaceutical composition comprises a monoclonal antibody or antigen-binding fragment thereof that binds to human CD38 of the present invention and a suitable formulation of a carrier, stabilizer, and / or excipient. The present invention provides pharmaceutical formulations comprising the monoclonal antibody or antigen-binding fragment thereof of the present invention. In some embodiments, the pharmaceutical composition of the present invention comprises the monoclonal antibody or antigen-binding fragment thereof of the present invention and a pharmaceutically acceptable carrier. To prepare a pharmaceutical composition or sterile composition, the antibody or antigen-binding fragment thereof is mixed with a pharmaceutically acceptable carrier or excipient. Therapeutic and diagnostic formulations can be prepared in the form of, for example, a lyophilized powder, slurry, aqueous solution, or suspension by mixing with a physiologically acceptable carrier, excipient, or stabilizer.

[0130] The toxicity and therapeutic efficacy of the antibody compositions, administered alone or in combination with immunosuppressants, can be determined in cell cultures or experimental animals by standard pharmaceutical methods, such as those used to determine the LD50 (the dose lethal to 50% of the population) and the ED50 (the dose effective in treating 50% of the population). The dose ratio between toxicity and therapeutic effect is the therapeutic index, which can be expressed as the ratio of LD50 to ED50. The data obtained from these cell culture assays and animal studies can be used to formulate a dosage range for use in humans. The dosage of the compound is preferably within a circulating concentration range that includes the ED50 with minimal or no toxicity. The dosage can vary within this range depending on the dosage form employed and the route of administration used.

[0131] Suitable routes of administration include parenteral administration (e.g., intramuscular, intravenous, or subcutaneous) and oral administration. Antibodies for pharmaceutical compositions or for practicing the methods of the present invention can be administered in a variety of conventional ways, such as oral ingestion, inhalation, topical application, or transdermal, subcutaneous, intraperitoneal, parenteral, intraarterial, or intravenous injection. In one embodiment, the binding compounds of the present invention are administered intravenously. In another embodiment, the binding compounds of the present invention are administered subcutaneously. Alternatively, antibodies can be administered in a local rather than systemic manner (typically a long-acting or sustained-release formulation), for example, by direct injection of the antibody into the site of action. In addition, antibodies can be administered in a targeted drug delivery system.

[0132] The appropriate dosage is determined by the clinician, for example, using parameters or factors known or suspected to affect treatment or expected to affect treatment in the art. Typically, the initial dose is slightly lower than the optimal dose and then increased by small amounts until the desired or optimal effect relative to any adverse side effects is achieved. Important diagnostic measurements include, for example, measuring inflammatory symptoms or the levels of inflammatory cytokines produced.

[0133] Antibodies, antibody fragments and cytokines can be provided by continuous infusion or by administration at certain intervals (e.g., one day, one week or 1-7 times per week). Dosage can be provided by intravenous, subcutaneous, intraperitoneal, percutaneous, local, oral, nasal, rectal, intramuscular, intracerebral, intraspinal or by suction. Preferred dosage regimen is the maximum dose or the scheme of dosing frequency including avoiding significant undesirable side effects. The weekly total dose is usually at least 0.05 μg / kg body weight, more generally at least 0.2 μg / kg, most generally at least 0.5 μg / kg, typically at least 1 μg / kg, more typically at least 10 μg / kg, most typically at least 109 μg / kg, preferably at least 0.2 mg / kg, more preferably at least 1.0 mg / kg, most preferably at least 2.0 mg / kg, ideally at least 10 mg / kg, more ideally at least 25 mg / kg, and most ideally at least 50 mg / kg. On a mole / kg basis, the required dosage of a small molecule therapeutic such as a peptidomimetic, natural product, or organic chemical is approximately the same as that of an antibody or polypeptide.

[0134] The pharmaceutical compositions of the present invention may also contain other agents, including but not limited to cytotoxic agents, cytostatic agents, anti-angiogenic or antimetabolite agents, targeted tumor drugs, immunostimulants or immunomodulators, or antibodies conjugated to cytotoxic agents, cytostatic agents, or other toxic drugs. The pharmaceutical compositions may also be administered in conjunction with other treatment modalities (e.g., surgery, chemotherapy, and radiation). Typical veterinary, experimental, or research subjects include monkeys, dogs, cats, rats, mice, rabbits, guinea pigs, horses, and humans.

[0135] Specifically, the monoclonal antibodies or antigen-binding fragments thereof that bind to human CD38 of the present invention can be used in combination with a second therapeutic agent used to treat the same cancer. In specific embodiments, the second therapeutic agent and the monoclonal antibody or antigen-binding fragment thereof of the present invention are administered at substantially the same time. Individuals sometimes receive a second therapeutic agent and a monoclonal antibody or antigen-binding fragment thereof of the present invention simultaneously. In one embodiment, the second therapeutic agent or other agent typically administered to cancer patients and the monoclonal antibody or antigen-binding fragment thereof of the present invention are combined into a pharmaceutical composition; in other embodiments, the two are administered separately.

[0136] The second therapeutic agent is any agent that is advantageously combined with an anti-CD38 antibody. Exemplary agents that may be advantageously combined with an anti-CD38 antibody include, but are not limited to, other agents that inhibit CD38 activity (including other antibodies or antigen-binding fragments thereof, peptide inhibitors, small molecule antagonists, etc.) and / or agents that interfere with CD38 upstream or downstream signal transduction. The second therapeutic agent may be a chemotherapeutic agent, a radiotherapeutic agent, or a biological agent. The biological agent may be a monoclonal antibody, an ADC, an oncolytic virus, or a CAR-T.

[0137] Treatment methods and applications

[0138] Another aspect of the present invention provides use of the monoclonal antibody or antigen-binding fragment thereof or pharmaceutical composition of the present invention in the preparation of a medicament for treating CD38-positive cancer or autoimmune disease.

[0139] In some embodiments, the monoclonal antibody comprises three heavy chain complementary determining regions HCDR1, HCDR2, and HCDR3 and three light chain complementary determining regions LCDR1, LCDR2, and LCDR3, wherein: the amino acid sequence of HCDR1 is as shown in SEQ ID NO: 1, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of HCDR2 is as shown in SEQ ID NO: 2, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of HCDR3 is as shown in SEQ ID NO: 6, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of LCDR1 is as shown in SEQ ID NO: 7, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of LCDR2 is as shown in SEQ ID NO: 9, or a conservative substitution variant thereof of one to three amino acids; and the amino acid sequence of LCDR3 is as shown in SEQ ID NO: 11, or a conservative substitution variant thereof of one to three amino acids. In some embodiments, the amino acid sequence of HCDR1 is shown as SEQ ID NO:1; the amino acid sequence of HCDR2 is shown as SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4 or SEQ ID NO:5; the amino acid sequence of HCDR3 is shown as SEQ ID NO:6; the amino acid sequence of LCDR1 is shown as SEQ ID NO:7 or SEQ ID NO:8; the amino acid sequence of LCDR2 is shown as SEQ ID NO:9 or SEQ ID NO:10; and the amino acid sequence of LCDR3 is shown as SEQ ID NO:11.

[0140] In some embodiments, the monoclonal antibody comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein:

[0141] (a) VH comprises the amino acid sequence of SEQ ID NO: 12 or a variant thereof having at least 85% sequence identity; VL comprises the amino acid sequence of SEQ ID NO: 18 or a variant thereof having at least 85% sequence identity;

[0142] (b) VH comprises the amino acid sequence of SEQ ID NO: 12, or a variant thereof having at least 85% sequence identity; VL comprises the amino acid sequence of SEQ ID NO: 21, or a variant thereof having at least 85% sequence identity; or

[0143] (c) VH comprises the amino acid sequence shown in SEQ ID NO: 14 or a variant thereof having at least 85% sequence identity; VL comprises the amino acid sequence shown in SEQ ID NO: 18 or a variant thereof having at least 85% sequence identity.

[0144] In some embodiments, the monoclonal antibody comprises a heavy chain and a light chain, wherein:

[0145] (a) the heavy chain comprises the amino acid sequence of SEQ ID NO: 28 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence of SEQ ID NO: 34 or a variant thereof having at least 85% sequence identity;

[0146] (b) the heavy chain comprises the amino acid sequence of SEQ ID NO: 28 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence of SEQ ID NO: 35 or a variant thereof having at least 85% sequence identity;

[0147] (c) the heavy chain comprises the amino acid sequence of SEQ ID NO: 29 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence of SEQ ID NO: 34 or a variant thereof having at least 85% sequence identity;

[0148] (d) the heavy chain comprises the amino acid sequence of SEQ ID NO: 30 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence of SEQ ID NO: 34 or a variant thereof having at least 85% sequence identity;

[0149] (e) the heavy chain comprises the amino acid sequence as shown in SEQ ID NO: 30 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence as shown in SEQ ID NO: 35 or a variant thereof having at least 85% sequence identity; or

[0150] (f) the heavy chain comprises the amino acid sequence of SEQ ID NO: 31 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence of SEQ ID NO: 34 or a variant thereof having at least 85% sequence identity.

[0151] In some embodiments, the monoclonal antibody binds to CD38, and the amino acid residues of the extracellular domain of CD38 to which it binds comprise at least one selected from the group consisting of K25, E28, I29, M33, and R34, wherein the amino acid residues are numbered according to the amino acid sequence of the extracellular domain of CD38 as set forth in SEQ ID NO: 36. In some embodiments, the monoclonal antibody binds to CD38, and the amino acid residues of the extracellular domain of CD38 to which it binds consist of K25, E28, I29, P31, E32, M33, R34, H35, K67, T70, Q71, T72, and V73.

[0152] Another aspect of the present invention provides a method for treating CD38-positive cancer or autoimmune disease using the monoclonal antibodies or antigen-binding fragments thereof or pharmaceutical compositions of the present invention, the method comprising administering a therapeutically effective amount of any one of the monoclonal antibodies or antigen-binding fragments thereof or any one of the pharmaceutical compositions of the present invention to a subject.

[0153] In some embodiments, the monoclonal antibody comprises three heavy chain complementary determining regions HCDR1, HCDR2, and HCDR3 and three light chain complementary determining regions LCDR1, LCDR2, and LCDR3, wherein: the amino acid sequence of HCDR1 is as shown in SEQ ID NO: 1, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of HCDR2 is as shown in SEQ ID NO: 2, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of HCDR3 is as shown in SEQ ID NO: 6, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of LCDR1 is as shown in SEQ ID NO: 7, or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of LCDR2 is as shown in SEQ ID NO: 9, or a conservative substitution variant thereof of one to three amino acids; and the amino acid sequence of LCDR3 is as shown in SEQ ID NO: 11, or a conservative substitution variant thereof of one to three amino acids. In some embodiments, the amino acid sequence of HCDR1 is shown as SEQ ID NO:1; the amino acid sequence of HCDR2 is shown as SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4 or SEQ ID NO:5; the amino acid sequence of HCDR3 is shown as SEQ ID NO:6; the amino acid sequence of LCDR1 is shown as SEQ ID NO:7 or SEQ ID NO:8; the amino acid sequence of LCDR2 is shown as SEQ ID NO:9 or SEQ ID NO:10; and the amino acid sequence of LCDR3 is shown as SEQ ID NO:11.

[0154] In some embodiments, the monoclonal antibody comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein:

[0155] (a) VH comprises the amino acid sequence of SEQ ID NO: 12 or a variant thereof having at least 85% sequence identity; VL comprises the amino acid sequence of SEQ ID NO: 18 or a variant thereof having at least 85% sequence identity;

[0156] (b) VH comprises the amino acid sequence of SEQ ID NO: 12, or a variant thereof having at least 85% sequence identity; VL comprises the amino acid sequence of SEQ ID NO: 21, or a variant thereof having at least 85% sequence identity; or

[0157] (c) VH comprises the amino acid sequence of SEQ ID NO: 14 or a variant thereof having at least 85% sequence identity; and VL comprises the amino acid sequence of SEQ ID NO: 18 or a variant thereof having at least 85% sequence identity.

[0158] In some embodiments, the monoclonal antibody comprises a heavy chain and a light chain, wherein:

[0159] (a) the heavy chain comprises the amino acid sequence of SEQ ID NO: 28 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence of SEQ ID NO: 34 or a variant thereof having at least 85% sequence identity;

[0160] (b) the heavy chain comprises the amino acid sequence of SEQ ID NO: 28 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence of SEQ ID NO: 35 or a variant thereof having at least 85% sequence identity;

[0161] (c) the heavy chain comprises the amino acid sequence of SEQ ID NO: 29 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence of SEQ ID NO: 34 or a variant thereof having at least 85% sequence identity;

[0162] (d) the heavy chain comprises the amino acid sequence of SEQ ID NO: 30 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence of SEQ ID NO: 34 or a variant thereof having at least 85% sequence identity;

[0163] (e) the heavy chain comprises the amino acid sequence as shown in SEQ ID NO: 30 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence as shown in SEQ ID NO: 35 or a variant thereof having at least 85% sequence identity; or

[0164] (f) the heavy chain comprises the amino acid sequence of SEQ ID NO: 31 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence of SEQ ID NO: 34 or a variant thereof having at least 85% sequence identity.

[0165] In some embodiments, the monoclonal antibody binds to CD38, and the amino acid residues of the extracellular domain of CD38 to which it binds comprise at least one selected from the group consisting of K25, E28, I29, M33, and R34, wherein the amino acid residues are numbered according to the amino acid sequence of the extracellular domain of CD38 as set forth in SEQ ID NO: 36. In some embodiments, the monoclonal antibody binds to CD38, and the amino acid residues of the extracellular domain of CD38 to which it binds consist of K25, E28, I29, P31, E32, M33, R34, H35, K67, T70, Q71, T72, and V73.

[0166] In some embodiments, the CD3 positive cancer of the present invention is a blood cancer or a solid tumor. In some embodiments, the blood cancer includes but is not limited to multiple myeloma (MM), leukemia (acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myeloid leukemia (CML), young myelomonocytic leukemia (JML), adult T cell lymphocytic leukemia (ATL), plasma cell leukemia) and lymphoma (small lymphocytic lymphoma, lymphoplasmacytic lymphoma, marginal zone lymphoma, follicular lymphoma, mantle cell lymphoma, diffuse large cell B cell lymphoma and Burkitt lymphoma). In some embodiments, the blood cancer is multiple myeloma (MM). In some embodiments, the blood cancer is relapsed / refractory multiple myeloma (R / R MM).

[0167] In some embodiments, the solid tumor includes but is not limited to melanoma, lung cancer, squamous non-small cell lung cancer (NSCLC), non-squamous NSCLC, colorectal cancer, prostate cancer, castration-resistant prostate cancer, gastric cancer, ovarian cancer, liver cancer, pancreatic cancer, thyroid cancer, head and neck squamous cell carcinoma, esophageal or gastrointestinal cancer, breast cancer, fallopian tube cancer, brain cancer, urethral cancer, genitourinary tract cancer, endometrial cancer, cervical cancer, lung adenocarcinoma, renal cell carcinoma (RCC) (e.g., renal clear cell carcinoma or renal papillary cell carcinoma), mesothelioma, nasopharyngeal carcinoma (NPC), esophageal cancer or gastrointestinal cancer, or metastatic lesions of any one thereof. In some embodiments, the solid tumor is lung cancer.

[0168] In some embodiments, the autoimmune disease is selected from rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, myasthenia gravis, type 1 diabetes, thrombocytopenic purpura, Sjogren's syndrome, Guillain-Barré syndrome, toxic diffuse goiter, vasculitis, asthma, lymphoma, Alzheimer's disease, amyloid cardiomyopathy, warm autoimmune hemolytic anemia (Warm Autoimmune Hemolytic Anemia (wAIHA)), colorectal cancer, immune thrombocytopenia, lupus nephritis, macroglobulinemia, hypergammaglobulinemia, autoimmune hemolytic anemia and neuromyelitis optica. In some embodiments, the autoimmune disease is systemic lupus erythematosus, warm autoimmune hemolytic anemia or immune thrombocytopenia.

[0169] Example

[0170] Example 1. Preparation and screening of hybridomas

[0171] CD38 monoclonal antibodies were prepared using hybridoma technology. BALB / c mice were immunized intramuscularly after mixing the recombinant CD38 extracellular domain with an equal volume of Freund's incomplete adjuvant. After three basic immunizations, tail vein blood was collected, and the antibody titer in the mouse serum was detected by ELISA. Three days before fusion, a shock immunization was performed. First, according to the experimental steps of hybridoma cell fusion, the spleens of immunized mice were fused with SP2 / 0 in batches. The fused cells were resuspended in medium containing HAT and transferred to 96-well plates. Labeled according to the number, they were cultured in a 37°C cell culture incubator, the culture medium was changed in time, and the growth was observed regularly. After 10-12 days of culture, the supernatant was taken for ELISA detection. The recombinant CD38 extracellular domain was purchased from Pujian Biotechnology (Wuhan) Technology Co., Ltd., catalog number ATMP00140HU, and its amino acid sequence is shown in the table below.

[0172] Table 1. Amino acid sequence of recombinant CD38 extracellular domain

[0173] Antibody clones capable of binding to CD38-positive cells were screened using ELISA and flow cytometry. Finally, hybridoma cells capable of binding to the CD38 extracellular domain with high affinity were screened using SPR technology. The ability of these hybridomas to induce cell apoptosis was tested using the Annexin V / PI apoptosis assay, and hybridoma H2 was selected.

[0174] As shown in Figure 1, H2 exhibited apoptotic activity on four CD38-positive cells: Daudi, Ramos, Raji, and SU-DHL-1. The apoptotic activity on Daudi, Ramos, and Raji cells was significantly superior to that of the positive control, Dara, and on SU-DHL-1 cells was comparable to that of the positive control, Dara. Biacore affinity testing results (Table 2) showed that the affinity constants of the H2 antibody were comparable to those of the positive control, Dara, indicating comparable binding affinity with Dara. The H2 monoclonal antibody was sequenced, and the sequence is shown in Table 3 below.

[0175] Table 2. Affinity test of H2 monoclonal antibody

[0176] Table 3. Complementarity determining region sequences and variable region sequences of H2 antibody

[0177] Example 2. Elisa assay for epitope competition occupancy

[0178] After coating with the CD38 antigen, H2 monoclonal antibody was added at varying concentrations and incubated for a sufficient period. Isa and Dara were then added at concentrations exceeding saturation, and binding to Isa and Dara was tested. If the binding site of the test antibody on the CD38 protein overlaps or blocks Isa or Dara, binding activity to Isa or Dara will be reduced. These results demonstrate that H2 antibody binds to different epitopes than Isa and Dara (Figure 2).

[0179] Example 3. Cross-reaction of CD38 antibodies with antigens from different species

[0180] Cross-reactivity of antibodies against CD38 antigens from different species was assessed using an ELISA. Coat the plates with CD38 antigens from different species (human, cynomolgus macaque, mouse, or rat) (1 μg / ml, 50 ml / well) and incubate overnight at 2-8°C. Antibody concentrations included: 300, 100, 33.3, 11.1, 3.7, 1.23, and 0.41 μg / ml.

[0181] Elisa results showed (Figure 3): Dara antibody bound to human antigens, but not to crab-eating macaque, mouse, or rat antigens; H2 antibody (Hybridoma-2) bound to human and monkey antigens, but not to mouse or rat antigens.

[0182] Example 4. Design, vector construction and expression of humanized H2 antibody and chimeric antibody

[0183] First, the sequence of the mouse antibody is used to search for the top-ranked sequences in the human framework library as candidate sequences. Then, the human sequence homology model is modeled onto the skeleton of the mouse antibody, the sequence of the mouse CDR is retained, and then the energy of the homology model is calculated to judge the stability of the humanized antibody. The humanized CDR mutant adopts the same strategy, except that the mouse CDR sequence is replaced with a mutant sequence and the structure of the antigen is retained. According to the humanized design and transformation, 18 humanized sequences were designed with H2 monoclonal antibody as the parent (labeled FLT004-hu-1 to FLT004-hu-18, the specific sequences are shown in Tables 4 to 6 below), and the target sequence was constructed according to the designed humanized sequence, and HEK293E was transiently transfected to express chimeric antibodies.

[0184] Table 4. CDR sequences of humanized antibodies

[0185] Table 5. Variable region sequences of humanized antibodies

[0186] Table 6. Constant region sequences of humanized antibodies

[0187] Example 5. Biacore affinity detection of humanized antibodies

[0188] The affinity of the humanized antibodies was tested by Biacore, and the results are shown in Table 7. Among them, the affinity constants of FTL004-hu-1 / 3 / 5 / 6 / 7 / 11 / 13 are comparable to the affinity constant of the positive control Dara, indicating that they have comparable binding affinity to Dara.

[0189] Table 7. Affinity analysis of humanized antibodies

[0190] Example 6. Detection of apoptosis activity of humanized antibodies

[0191] The apoptosis activity of the humanized antibodies was tested, and some of the results are shown in Figure 4. The results showed that FTL004-hu-1 / 6 / 7 had the best apoptosis-inducing activity and exhibited superior apoptosis-inducing activity to the positive control, Isa, in both Ramos and Raji cells. FTL004-hu-13 had the second-best apoptosis activity, exhibiting comparable apoptosis-inducing activity to the positive control, Isa, in Ramos cells and superior apoptosis-inducing activity to the positive control, Isa, in Raji cells.

[0192] The activity of the humanized antibodies was tested by ELISA. The results are shown in Figure 5. A comprehensive comparison of the absorbance curves and EC50 values ​​shows that FTL004-hu-1 / 3 / 5 / 6 / 7 / 9 (corresponding to humanized-1 / 3 / 5 / 6 / 7 / 9 in the figure, respectively) have good activity, all better than the positive control Isa; FTL004-hu-11 / 12 / 13 / 15 / 17 (corresponding to humanized-11 / 12 / 13 / 15 / 17 in the figure, respectively) have the second best activity.

[0193] Example 7. Antibody stability study

[0194] High-Temperature Stability: Humanized antibody samples were stored at -20°C and 40°C for one week, and the percentages of aggregates, monomers, and fragments in the samples were analyzed. The results are shown in the table below. Some antibodies showed no significant change in SEC purity after storage at 40°C for one week. Combined with initial product purity analysis, it is believed that FTL004-hu-1 / 2 / 5 / 6 / 7 (corresponding to FTL004-hum-1 / 2 / 5 / 6 / 7 in Table 8, respectively) exhibited good initial purity and stability, suggesting advantages in light and heavy chain expression, assembly, and secretion in cells. The results are shown in Table 8.

[0195] Table 8. High temperature stability analysis of humanized antibodies

[0196] Oxidative stability: Selected samples with high activity were subjected to oxidative stability testing. The results are shown in the table below. It can be seen that after 6 and 24 hours of exposure to 0.1% H₂O₂, the SEC fragment peak content increased. The results are shown in Table 9. A comprehensive comparison showed that antibodies FTL004-hu-1 / 2 / 6 / 7 / 13 had the best oxidative stability, with minimal increases in fragment peak content. Antibodies FTL004-hu-5 / / 9 / 11 / 15 / 17 showed poor stability, with significant increases in fragment peak content.

[0197] Table 9. Oxidative stability analysis of humanized antibodies

[0198] Based on the above results, it is preliminarily believed that the physical and chemical properties of FTL004-hu-1 / 6 / 7 antibodies are superior. A comprehensive stability test was conducted on the three (the results are shown in Table 10 below). Humanized antibody No. 1 has the best stability, is sensitive to oxidation, and is relatively stable to high temperature, acid, alkali, freeze-thaw, etc.

[0199] Table 10. Comprehensive stability analysis of humanized antibodies

[0200] In summary, the activity and physicochemical properties of FTL004-hu-1 / 6 / 7 antibodies were considered to be superior. These three antibodies were used for subsequent Fc mutation modification.

[0201] Example 8. In vivo pharmacodynamics of humanized antibodies

[0202] Based on the previous screening results, three humanized antibodies FTL004-hu-1 / 6 / 7 with high affinity, good activity, and good stability were selected for further animal pharmacodynamic testing. Animals: NSG mice, 3-5 males per group; cell line: SU-DHL-6, subcutaneously transplanted (1×10 7 Dosage and frequency: 0, 2.5, and 10 mg / kg; Q2Wx8 (low-dose group received 6 doses in total); indicators: tumor volume, tumor weight, and liver and kidney weights.

[0203] Tumor growth curves (Figure 6) show that intraperitoneal administration of 10 mg / kg FTL004-hu-1 (q2wx8) significantly inhibited tumor growth in SU-DHL-6 tumor-bearing mice, significantly outperforming Dara and Isa at the same doses. While FTL004-hu-6 and 7 at 10 mg / kg showed less inhibitory activity than FTL004-hu-1, they were still superior to Dara and Isa at the same doses. At the 27-day endpoint, tumors were dissected and weighed, and tumor inhibition rates were calculated (Figure 7). The inhibition rates for the experimental groups were as follows: 12.96% for the Dara group; 2.78% for the Isa group; 59.26% for the FTL004-hu-1 group; 29.63% for the FTL004-hu-6 group; and 42.59% for the FTL004-hu-7 group. These results demonstrate that the tumor inhibition rates of FTL004-hu-1, 6, and 7 were significantly superior to those of the positive controls, Dara and Isa. Gross observation and weighing of the liver and kidneys (Figure 8) revealed that Dara, Isa, and FTL004-hu-1 / 6 / 7 had no obvious hepatotoxicity or renal toxicity.

[0204] Example 9. Antibody Fc segment modification

[0205] The Fc region of an antibody interacts with numerous Fc receptors and ligands, producing a range of biological effects. For the IgG Fc region, the Fc receptor family—FcγR—plays a key role. The formation of the Fc / FcγR complex effectively recruits corresponding effector cells, leading to intracellular signal transduction and a series of subsequent important immune responses, such as the release of inflammatory mediators, B cell activation, endocytosis, phagocytosis, and cytotoxicity. Fc region engineering can enhance antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cell-mediated phagocytosis (ADCP), and complement-mediated cytotoxicity (CDC).

[0206] The Fc region of the FTL004-hu-1 / 6 / 7 antibodies was modified according to methods known in the art. The modified FTL004-hu-1 / 6 / 7 antibodies were named FTL004-1 / 6 / 7, respectively. The serine residue at position 19 of the Fc region was substituted with an aspartic acid residue (S19D), the isoleucine residue at position 112 was substituted with a glutamic acid residue (I112E), the aspartic acid residue at position 136 was substituted with a glutamic acid residue (D136E), and the leucine residue at position 138 was substituted with a methionine residue (L138M). The glycine residues and lysine residues at positions 226 and 227 were deleted and named FTL004-1 / 6 / 7. The N-terminus of the antibody sequence further included a signal peptide as shown in SEQ ID NO: 32 (the specific sequence of which is shown in Table 12 below). The activities and physicochemical properties of the antibodies before and after modification were compared.

[0207] Table 11. Sequences of Fc segment before and after modification

[0208] Table 12. Sequences of signal peptides

[0209] Table 13. Antibody sequences before and after humanized antibody Fc segment modification

[0210] Biacore affinity testing of the antibodies before and after Fc modification revealed no significant change in antigen-binding affinity after Fc mutation. The apoptosis-inducing activity of the antibodies before and after Fc mutation was assessed using the same method described above. The results are shown in Table 14 below. Both the Fc-mutated and Fc-mutated antibodies demonstrated a moderate apoptosis-inducing ability on all four CD38-positive cell lines, and were superior to the positive control antibodies Dara and Isa.

[0211] Table 14. Apoptosis-inducing activity of humanized antibody Fc segment before and after modification

[0212] The activity of the Fc-mutated antibodies was assessed by ELISA. As shown in Figure 9, the ELISA activities of FTL004-1 / 6 / 7 were similar, with FTL004-1 having slightly higher activity than FTL004-6 / 7. There was no significant difference in activity compared to FTL004-hu-1 / 6 / 7.

[0213] The binding of the Fc-mutated antibodies to Fcγ receptors was tested using methods known in the art. The test results are shown in Table 15 below, indicating that the Fc-mutated antibodies exhibited increased binding to FcγRIIIa(V) and FcγRIIIa(F).

[0214] Table 15. Binding of humanized antibody Fc segments to Fcγ receptors

[0215] Example 10. In vivo pharmacodynamics of Fc-modified antibodies

[0216] Animals: Male NSG mice, 3 per group; Cell line: SU-DHL-6, subcutaneously implanted (1×107 cells / 0.2 ml / mouse). Dosage and frequency: 10 and 30 mg / kg, every 2 weeks x 8. Indicators: Tumor volume, tumor weight, and liver and kidney weights. 10 mg / kg and 30 mg / kg of FTL004-1, FTL004-7, FTL004-hu-1, 30 mg / kg of Isa, and FTL004-1 + Dara (all at 10 mg / kg) were administered intraperitoneally every 2 weeks x 8.

[0217] The results are shown in Figure 10. From the 4th dose to the 8th dose, FTL004-1 could inhibit the growth of tumors in SU-DHL-6 tumor-bearing mice. There was a certain dose correlation between low and high doses of FTL004-1. At the end of the experiment after 29 days of administration, the tumors were dissected and weighed, and the tumor inhibition rate was calculated (Figure 11). The tumor inhibition rates of the experimental groups were as follows: 7.407% in the Isa 30 mg / kg group; 7.407% in the FTL004-1 10 mg / kg group; 18.518% in the FTL004-1 30 mg / kg group; 33.333% in the FTL004-7 10 mg / kg group; 18.518% in the FTL004-7 30 mg / kg group; 25.925% in the FTL004-hu-1 10 mg / kg group; -18.518% in the FTL004-hu-1 30 mg / kg group; and -7.407% in the FTL004-hu-1 10 mg / kg + Dara 10 mg / kg group. The above tumor tissues were frozen and sectioned, and positive tissues were stained with FTL004-1 antibody. It was found that the FTL004 antibody showed a weak positive reaction ( FIG. 12 ).

[0218] Example 11. CD38 Antibody Induces Apoptosis in CD38-Positive Solid Tumor Cells

[0219] After screening a variety of solid tumor cell lines, we obtained CD38 strongly positive small cell lung cancer H211 cells, moderately positive non-small cell lung cancer A549 cells, weakly positive non-small cell lung cancer H157 cells, and prostate cancer cell DU145 cells.

[0220] Apoptosis experiments were performed on CD38-positive solid tumor cells. As shown in Table 16 below, no significant apoptosis was observed in DU145 and H157 cells, which have low CD38 expression. However, in H211 small cell lung cancer cells, which have high CD38 expression, different antibodies showed different apoptosis-inducing abilities, with FTL004-1 being relatively superior.

[0221] Table 16. Apoptosis rate of CD38 positive cancer cells induced by CD38 antibody

[0222] Example 12. In vivo killing effect of CD38 antibody on small cell lung cancer H211 cells

[0223] Animals: NCG mice, 4 per group, male; cell line: NCI-H211, subcutaneous transplantation (1×10 7 Dosage and frequency: 30 mg / kg (FTL004-1 and Isatuximab); Q2Wx8; Indicators: tumor volume, tumor weight, and liver and kidney weights.

[0224] The experimental results are shown in Figure 13. It can be seen that 30 mg / kg of FTL004-1 and Isa were intravenously injected twice a week for 8 times, and both showed a trend of inhibiting the growth of NCI-H211 subcutaneous tumors. The tumor inhibition effect of FTL004-1 at the same dose was slightly better than that of Isa.

[0225] Example 13. Binding experiment of CD38 antibody to H211 and SU-DHL-6 cells

[0226] Flow cytometry was used to detect the binding of Dara, Isa, and FTL004-1 antibodies to CD38-positive H211 and SU-DHL-6 cells at different concentration gradients and to confirm their binding EC50.

[0227] The results showed ( FIG. 14 ) that the EC50 value of the FTL004-1 antibody (corresponding to 004-1 in FIG. 14 ) was similar to that of the Isa antibody, and the Dara value was higher, especially on H211 cells, with an EC50 of 1.940 μg / ml.

[0228] Example 14. Binding experiment of CD38 antibody to red blood cells and PBMC

[0229] Flow cytometry was used to examine the binding of CD38 antibodies to rhesus monkey erythrocytes. Dara and Isa showed no binding to monkey erythrocytes, while FTL004-1 showed some binding to monkey erythrocytes with an EC50 value of approximately 2-5 μg / ml. Flow cytometry was also used to examine the binding of CD38 antibodies to normal human erythrocytes. As shown in Figure 15 , Dara exhibited high binding to healthy (normal) human erythrocytes. Isa also exhibited some binding to normal human erythrocytes, but the binding was relatively weak. FTL004-1 showed no binding to normal human erythrocytes. Flow cytometry was used to examine the binding of CD38 antibodies to healthy human PBMCs. As shown in Figure 16 , both Dara and FTL004-1 (corresponding to 004-1 in Figure 16 ) showed positive binding to normal human PBMCs.

[0230] Example 15. Three-dimensional structural analysis of the CD38 / FTL004-Fab complex

[0231] To gain a clearer understanding of the molecular mechanism of the interaction between FTL004 and human CD38 and to identify the binding site of FTL004 to CD38, we determined the structure of the CD38-ECD-his complex with FTL004-1Fab at a resolution of 3.86 Å using cryo-electron microscopy with C1 symmetry.

[0232] Human CD38-ECD-his (sequence shown in the table below) was mixed with the FTL004-1-Fab fragment at a 1:1 ratio and incubated overnight at 4°C. The antibody-antigen mixture was loaded onto a Superdex 200 10 / 300 column (Cytiva) using a constant flow rate of 0.5 mL / min in SEC buffer (20 mM Tris, 150 mM NaCl, pH 7.2). The complex peak was harvested, concentrated to 0.50 mg / mL in SEC buffer, and immediately used for cryo-EM grid preparation.

[0233] Table 17 Amino acid sequences of CD38 extracellular domain fragments

[0234] The structure of the CD38 / FTL004-1 complex was then determined using cryo-electron microscopy at a resolution of 3.86 angstroms (Figure 17A). Five complementarity-determining regions (CDRs) of FTL004-1 were involved in the interaction with CD38, with only LCDR2 not participating (Figure 17B). FTL004-1 recognized 13 residues of human CD38 through hydrogen bonds, salt bridges, and extensive van der Waals interactions (Figures 17C and 17D), namely K25, E28, I29, P31, E32, M33, R34, H35, K67, T70, Q71, T72, and V73. When the CD38 / daratumumab (PDB code 7DHA) and CD38 / isatuximab (PDB code 4CMH) complexes were superimposed on the CD38 / FTL004-1-Fab complex (as shown in Figure 17E), it was found that the binding site of FTL004-1 was completely different from that of daratumumab; it was not identical to that of isatuximab, with the different amino acid residues K25, E28, I29, M33, and R34, which may have significantly contributed to FTL004-1's ability to enhance apoptosis. Figure 17F further shows the possible orientation of CD38 on the cell surface and the different epitopes of FTL004-1, daratumumab, and isatuximab. It can be seen that the binding site of FTL004-1 on CD38 appears to be closer to the cell membrane.

[0235] It should be understood that, although the present invention has been specifically disclosed by preferred embodiments and optional features, those skilled in the art may make modifications, improvements and variations to the invention disclosed herein, and these modifications, improvements and variations are considered to be within the scope of the present invention. The materials, methods and examples provided herein are representative and exemplary of preferred embodiments and are not intended to be limiting of the scope of the present invention.

Claims

1. A monoclonal antibody or antigen-binding fragment thereof that binds to human CD38, wherein the amino acid residues of the CD38 extracellular domain fragment to which it binds comprise at least one selected from the group consisting of K25, E28, I29, M33, and R34, wherein the amino acid residues are numbered according to the amino acid sequence of the CD38 extracellular domain fragment as shown in SEQ ID NO:

36.

2. The monoclonal antibody or antigen-binding fragment thereof according to claim 1, wherein the amino acid residues of the CD38 extracellular domain fragment to which it binds include K25, E28, I29, M33 and R34.

3. The monoclonal antibody or antigen-binding fragment thereof according to claim 2, wherein the amino acid residues of the CD38 extracellular domain fragment to which it binds further comprise at least one selected from the group consisting of P31, E32, H35, K67, T70, Q71, T72, and V73.

4. The monoclonal antibody or antigen-binding fragment thereof according to claim 2, wherein the amino acid residues of the CD38 extracellular domain fragment to which it binds further comprise P31, E32, H35, K67, T70, Q71, T72, and V73.

5. The monoclonal antibody or antigen-binding fragment thereof according to claim 4, wherein the amino acid residues of the CD38 extracellular domain fragment to which it binds consist of K25, E28, I29, P31, E32, M33, R34, H35, K67, T70, Q71, T72 and V73.

6. The monoclonal antibody or antigen-binding fragment thereof according to claim 1, wherein the antigen-binding fragment is selected from the group consisting of Fv, scFv, (scFv)2, Fab, Fab' and F(ab')2. The monoclonal antibody or antigen-binding fragment thereof according to claim 1 , which does not bind to healthy human red blood cells. 8 . A pharmaceutical composition comprising the monoclonal antibody or antigen-binding fragment thereof according to claim 1 , and a pharmaceutically acceptable carrier.

9. Use of the monoclonal antibody or antigen-binding fragment thereof according to any one of claims 1 to 7 in the preparation of a medicament for treating CD38-positive cancer or autoimmune disease.

10. The use according to claim 9, wherein the cancer is a blood cancer.

11. The use according to claim 10, wherein the blood cancer is selected from multiple myeloma, leukemia or lymphoma.

12. The use according to claim 11, wherein the leukemia is selected from acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myelocytic leukemia (CML), young myelomonocytic leukemia (JML), adult T-cell lymphocytic leukemia (ATL) and plasma cell leukemia; and the lymphoma is selected from small lymphocytic lymphoma, lymphoplasmacytic lymphoma, marginal zone lymphoma, follicular lymphoma, mantle cell lymphoma, diffuse large cell B-cell lymphoma and Burkitt lymphoma.

13. The use according to claim 9, wherein the cancer is a solid tumor.

14. The method of claim 13, wherein the solid tumor is selected from the group consisting of melanoma, lung cancer, squamous non-small cell lung cancer (NSCLC), non-squamous NSCLC, colorectal cancer, prostate cancer, castration-resistant prostate cancer, gastric cancer, ovarian cancer, liver cancer, pancreatic cancer, thyroid cancer, head and neck squamous cell carcinoma, esophageal or gastrointestinal cancer, breast cancer, fallopian tube cancer, brain cancer, urethral cancer, genitourinary tract cancer, endometrial cancer, cervical cancer, lung adenocarcinoma, renal cell carcinoma (RCC), mesothelioma, nasopharyngeal carcinoma (NPC), esophageal cancer, and gastrointestinal cancer.

15. The use according to claim 9, wherein the autoimmune disease is selected from rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, myasthenia gravis, type 1 diabetes, thrombocytopenic purpura, Sjogren's syndrome, Guillain-Barré syndrome, toxic diffuse goiter, vasculitis, asthma, lymphoma, Alzheimer's disease, amyloid cardiomyopathy, warm autoimmune hemolytic anemia, colorectal cancer, immune thrombocytopenia, lupus nephritis, macroglobulinemia, hypergammaglobulinemia, autoimmune hemolytic anemia and neuromyelitis optica.

16. The use according to claim 15, wherein the autoimmune disease is systemic lupus erythematosus, warm autoimmune hemolytic anemia or immune thrombocytopenia.

17. Use of a monoclonal antibody or an antigen-binding fragment thereof that binds to human CD38 in the preparation of a medicament for treating an autoimmune disease, wherein the monoclonal antibody comprises three heavy chain complementary determining regions (HCDR1, HCDR2, and HCDR3) and three light chain complementary determining regions (LCDR1, LCDR2, and LCDR3), wherein: The amino acid sequence of HCDR1 is as shown in SEQ ID NO: 1 or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of HCDR2 is as shown in SEQ ID NO: 2 or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of HCDR3 is as shown in SEQ ID NO: 6 or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of LCDR1 is as shown in SEQ ID NO: 7 or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of LCDR2 is as shown in SEQ ID NO: 9 or a conservative substitution variant thereof of one to three amino acids; the amino acid sequence of LCDR3 is as shown in SEQ ID NO: 11 or a conservative substitution variant thereof of one to three amino acids.

18. The use according to claim 17, wherein: The amino acid sequence of HCDR1 is shown in SEQ ID NO: 1; the amino acid sequence of HCDR2 is shown in SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4 or SEQ ID NO: 5; the amino acid sequence of HCDR3 is shown in SEQ ID NO: 6; the amino acid sequence of LCDR1 is shown in SEQ ID NO: 7 or SEQ ID NO: 8; the amino acid sequence of LCDR2 is shown in SEQ ID NO: 9 or SEQ ID NO: 10; and the amino acid sequence of LCDR3 is shown in SEQ ID NO:

11.

19. The use according to claim 17, wherein: HCDR1, its amino acid sequence is shown in SEQ ID NO: 1; HCDR2, its amino acid sequence is shown in SEQ ID NO: 2; HCDR3, its amino acid sequence is shown in SEQ ID NO: 6; LCDR1, its amino acid sequence is shown in SEQ ID NO: 7; LCDR2, its amino acid sequence is shown in SEQ ID NO: 9; LCDR3, its amino acid sequence is shown in SEQ ID NO:

11.

20. The use according to claim 17, wherein: HCDR1, its amino acid sequence is shown in SEQ ID NO: 1; HCDR2, its amino acid sequence is shown in SEQ ID NO: 2; HCDR3, its amino acid sequence is shown in SEQ ID NO: 6; LCDR1, its amino acid sequence is shown in SEQ ID NO: 8; LCDR2, its amino acid sequence is shown in SEQ ID NO: 10; LCDR3, its amino acid sequence is shown in SEQ ID NO:

11.

21. The use according to claim 17, wherein the monoclonal antibody comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein VH comprises the amino acid sequence shown in SEQ ID NO: 12 or SEQ ID NO: 14, or a variant thereof having at least 85% sequence identity; and VL comprises the amino acid sequence shown in SEQ ID NO: 18 or SEQ ID NO: 21, or a variant thereof having at least 85% sequence identity.

22. The use according to claim 21, wherein (a) VH comprises the amino acid sequence of SEQ ID NO: 12 or a variant thereof having at least 85% sequence identity; VL comprises the amino acid sequence of SEQ ID NO: 18 or a variant thereof having at least 85% sequence identity; (b) VH comprises the amino acid sequence of SEQ ID NO: 12, or a variant thereof having at least 85% sequence identity; VL comprises the amino acid sequence of SEQ ID NO: 21, or a variant thereof having at least 85% sequence identity; or (c) VH comprises the amino acid sequence shown in SEQ ID NO: 14 or a variant thereof having at least 85% sequence identity; VL comprises the amino acid sequence shown in SEQ ID NO: 18 or a variant thereof having at least 85% sequence identity.

23. The use according to claim 17, wherein the Fc region of the monoclonal antibody is modified to enhance binding to FcγRIIIa(V) and / or FcγRIIIa(F).

24. The use according to claim 23, wherein the Fc segment comprises the amino acid sequence shown in SEQ ID NO: 27 or a variant thereof having at least 85% sequence identity thereto.

25. The use according to claim 17, wherein the monoclonal antibody comprises a heavy chain and a light chain, the heavy chain comprises the amino acid sequence as shown in SEQ ID NO: 28, SEQ ID NO: 29, SEQ ID NO: 30 or SEQ ID NO: 31 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence as shown in SEQ ID NO: 34 or SEQ ID NO: 35 or a variant thereof having at least 85% sequence identity.

26. The use according to claim 25, wherein (a) the heavy chain comprises the amino acid sequence of SEQ ID NO: 28 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence of SEQ ID NO: 34 or a variant thereof having at least 85% sequence identity; (b) the heavy chain comprises the amino acid sequence of SEQ ID NO: 28 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence of SEQ ID NO: 35 or a variant thereof having at least 85% sequence identity; (c) the heavy chain comprises the amino acid sequence of SEQ ID NO: 29 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence of SEQ ID NO: 34 or a variant thereof having at least 85% sequence identity; (d) the heavy chain comprises the amino acid sequence of SEQ ID NO: 30 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence of SEQ ID NO: 34 or a variant thereof having at least 85% sequence identity; (e) the heavy chain comprises the amino acid sequence as shown in SEQ ID NO: 30 or a variant thereof having at least 85% sequence identity, and the light chain comprises the amino acid sequence as shown in SEQ ID NO: 35 or a variant thereof having at least 85% sequence identity; or (f) the heavy chain comprises the amino acid sequence as shown in SEQ ID NO: 31 or a variant thereof having at least 85% sequence identity thereto, The light chain comprises the amino acid sequence shown in SEQ ID NO: 34 or a variant thereof having at least 85% sequence identity thereto.

27. The use according to claim 17, wherein the antigen-binding fragment is selected from the group consisting of Fv, scFv, (scFv)2, Fab, Fab' and F(ab')2.

28. The use according to claim 17, wherein the monoclonal antibody is of IgG1 type.

29. The use according to claim 17, wherein the monoclonal antibody or antigen-binding fragment thereof does not bind to healthy human red blood cells.

30. The use according to claim 17, wherein the affinity constant Kd of the monoclonal antibody determined by Biacore is 10 -9 M level.

31. The use according to claim 17, wherein the autoimmune disease is selected from rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, myasthenia gravis, type 1 diabetes, thrombocytopenic purpura, Sjogren's syndrome, Guillain-Barré syndrome, toxic diffuse goiter, vasculitis, asthma, lymphoma, Alzheimer's disease, amyloid cardiomyopathy, warm autoimmune hemolytic anemia, colorectal cancer, immune thrombocytopenia, lupus nephritis, macroglobulinemia, hypergammaglobulinemia, autoimmune hemolytic anemia and neuromyelitis optica.

32. The use according to claim 31, wherein the autoimmune disease is systemic lupus erythematosus, warm autoimmune hemolytic anemia or immune thrombocytopenia.

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