Recycling antibody for fat loss and muscle gain

Abstract

Provided is a recycling antibody for fat loss and muscle gain. Specifically, the present invention relates to an engineered anti-ACVR2B antibody having pH-dependent antigen binding. The antibody can be used for treating indications including lipid metabolism disorders and / or muscle atrophy-related diseases. The antibody has a longer half-life and stronger efficacy in vivo. Compared with intravenously injected Bimagrumab, the antibody is suitable for administration by means of subcutaneous injection due to its low dosage requirement.

Description

A recirculating antibody for fat loss and muscle gain Technical Field

[0001] This invention relates to the field of biomedicine, and more specifically to a recirculating antibody that promotes fat loss and muscle gain. Background Technology

[0002] Statistics show that the number of obese people worldwide has nearly tripled, currently reaching 650 million, and may reach 1.12 billion by 2030. Obesity increases risk factors for many diseases, such as cardiovascular disease (heart disease and stroke), diabetes, musculoskeletal disorders, especially osteoarthritis, resulting in a heavy disease burden.

[0003] Recent studies have shown that 25%-40% of the weight loss in smegglutide subjects was lean mass, primarily composed of muscle. Muscle is crucial for health. Muscle fibers synthesize and release cytokines and polypeptides (collectively known as myokines). These myokines mediate interactions between muscles and other organs (including the brain, adipose tissue, bones, liver, intestines, pancreas, vascular bed, and skin) and within the muscles themselves through autocrine, paracrine, or endocrine mechanisms. As muscle breaks down and atrophies, the reduction in muscle mass leads to the loss of amino acids and these important myokines, making the body less resistant to external stimuli. Muscle loss can lead to a range of health risks. A 10% reduction in lean mass can result in decreased immunity and increased risk of infection; a 20% reduction can cause impaired wound healing and muscle weakness; a 30% reduction can lead to difficulty sitting, pressure ulcers, pneumonia, and slow wound healing; and a reduction of more than 40% can directly increase the risk of death, usually due to pneumonia. Muscle loss increases the risk of cardiovascular disease, osteoporosis, and other diseases. In particular, for the elderly, muscle loss also means an increased risk of death.

[0004] The neonatal Fc receptor (FcRn) is an MH1-like heterodimer that plays a central role in cellular transport and the serum half-life of IgG. mAbs typically circulate back to plasma from the body via the FcRn circulation system, resulting in a longer half-life and lower clearance rate in vivo. The binding of the Fc region of IgG antibodies to FcRn prolongs the half-life. The binding of the Fc region of IgG to FcRn is pH-dependent, exhibiting high affinity for FcRn under acidic intracellular conditions and rapid dissociation under slightly alkaline blood conditions. This receptor-mediated recycling mechanism prolongs the half-life of IgG. Henne et al. modified the Fc region of a modified anti-PCSK9 recirculating antibody. In FcRn affinity tests, the mutant showed a 7-fold increase in affinity compared to the parent antibody, and a 2-fold increase in half-life in cynomolgus monkeys, indicating that modifications to the Fc region to enhance affinity for FcRn under acidic conditions improve antibody half-life. The mutation sites M252Y, S254T, and T256E (called YTE) identified by MedImmune can extend the half-life of IgG in cynomolgus monkeys to nearly four times. In the acidic environment of the endosome, IgG antibodies can be captured by FcRn and circulate to the extracellular space, which is the main reason why this type of antibody is not subject to nonspecific clearance.

[0005] Therefore, there is an urgent need in this field to develop a pH-dependent antibody with a longer half-life and better fat loss and muscle gain effects. Summary of the Invention

[0006] The purpose of this invention is to provide a pH-dependent antibody with a longer half-life and better fat loss and muscle gain effects.

[0007] In a first aspect of the invention, a human antibody or antigen-binding fragment thereof having pH-dependent antigen binding is provided, comprising a light chain variable region and a heavy chain variable region of bismagnumab or a variant having the same or similar biological activity therewith, wherein at least one CDR domain of the light chain variable region and / or the heavy chain variable region is mutated by substituting one or more amino acids within the CDR domain with histidine residues, thereby producing a mutated bismagnumab or a bismagnumab variant that induces pH-dependent antigen binding, wherein the ratio of the affinity constant (KD) of the mutated bismagnumab to that of the antigen bound at pH 6 to that bound at pH 7.2, as measured by Biolayer Interferometry, is K1, and the ratio of the affinity constant of the non-mutated bismagnumab to that of the antigen bound at pH 6 to that bound at pH 7.2, is K0, wherein K1 / K0 is r, and r ≥ 1.3.

[0008] In another preferred embodiment, r ≥ 10, more preferably ≥ 20, more preferably ≥ 50, and even more preferably ≥ 100.

[0009] In another preferred embodiment, r ≤ 5000, more preferably ≤ 3000.

[0010] In another preferred embodiment, the human antibody or antigen-binding fragment thereof having pH-dependent antigen binding comprises a variant having the same or similar biological activity as the light chain variable region and heavy chain variable region of the human antibody bimagrumab, the variant causing pH-dependent antigen binding, wherein,

[0011] The ratio of antigen affinity constants of the mutated bismagnumab to that of the non-mutated bismagnumab at pH 6 and pH 7, as measured by Biolayer Interferometry (Octet Red), is K1, and the ratio of antigen affinity constants of the non-mutated bismagnumab is K0, where K1 / K0 is r, and r≥1.7.

[0012] In another preferred embodiment, r is 1.7-70, more preferably, r is 2-68, and even more preferably, r is 2-5.

[0013] In another preferred embodiment, r ≥ 2.

[0014] In another preferred embodiment, the human antibody refers to a humanized anti-ACVR2B antibody.

[0015] In another preferred embodiment, the antigen or the pH-dependent antigen is ACVR2B.

[0016] In another preferred embodiment, the mutation of the at least one, two, or three CDR domains by replacing one or more amino acids within the CDR domain with histidine residues includes mutations of one, two, three, four, or five amino acids.

[0017] In another preferred embodiment, the mutated bimagglutinum antibody retains 4-5 identical CDR domains compared to the original bimagglutinum antibody, and 1-2 CDR domains have amino acid mutations.

[0018] In another preferred embodiment, the amino acid mutation includes a derived sequence that has optionally been added, deleted, modified, and / or substituted with at least one amino acid and is capable of retaining binding affinity.

[0019] In another preferred embodiment, the mutant bimagnumab or bimagnumab variant comprises an HCDR1 sequence selected from the following: SEQ ID NO: 7-11.

[0020] In another preferred embodiment, the mutant bimagnumab or bimagnumab variant comprises an HCDR2 sequence selected from the following: SEQ ID NO: 12-28, 67-70.

[0021] In another preferred embodiment, the mutant bimagnumab or bimagnumab variant comprises an HCDR3 sequence selected from the following: SEQ ID NO: 29-34, 70-72.

[0022] In another preferred embodiment, the mutant bimagnumab or bimagnumab variant comprises an LCDR1 sequence selected from the following: SEQ ID NO: 35-48, 73-76.

[0023] In another preferred embodiment, the mutant bimagnumab or bimagnumab variant comprises an LCDR2 sequence selected from the following: SEQ ID NO: 49-55.

[0024] In another preferred embodiment, the mutant bimagnumab or bimagnumab variant comprises an LCDR3 sequence selected from the following: SEQ ID NO: 56-66, 77 or 78.

[0025] In another preferred embodiment, the binding fragment comprises a sequence selected from the group consisting of the remaining sequences identical to the CDR region sequence of the non-mutated bimagglutinumab:

[0026] HCDR1, as shown in SEQ ID NO: 7 or SEQ ID NO: 8,

[0027] HCDR2 as shown in SEQ ID NO: 12, 13, 16, 17, 20, 21, 24, 25, 26, 28, 67, 68 or 70,

[0028] HCDR3, as shown in SEQ ID NO: 29, 30, 33 or 34,

[0029] LCDR1 as shown in SEQ ID NO: 35, 36, 37, 39, 40, 42, 43, 44, 45, 47, 73, 74, 75, 76 or 78,

[0030] LCDR2 as shown in SEQ ID NO: 49, 52, 53 or 55,

[0031] LCDR3 as shown in SEQ ID NO: 56, 58, 59, 61, 62, 63, 64 or 65, or a combination thereof.

[0032] In another preferred embodiment, the binding fragment comprises three heavy chain complementarity-determining regions (HCDR1, HCDR2, and HCDR3) and three light chain complementarity-determining regions (LCDR1, LCDR2, and LCDR3), wherein,

[0033] The HCDR1 sequence is SEQ ID NO: 1;

[0034] The HCDR2 sequence is SEQ ID NO: 20;

[0035] The HCDR3 sequence is SEQ ID NO: 3;

[0036] The LCDR1 sequence is SEQ ID NO: 4;

[0037] The LCDR2 sequence is SEQ ID NO: 5; and

[0038] The LCDR3 sequence is SEQ ID NO: 6; or

[0039] The HCDR1 sequence is SEQ ID NO: 1;

[0040] The HCDR2 sequence is SEQ ID NO: 24;

[0041] The HCDR3 sequence is SEQ ID NO: 3;

[0042] The LCDR1 sequence is SEQ ID NO: 4;

[0043] The LCDR2 sequence is SEQ ID NO: 5; and

[0044] The LCDR3 sequence is SEQ ID NO: 6; or

[0045] The HCDR1 sequence is SEQ ID NO: 1;

[0046] The HCDR2 sequence is SEQ ID NO: 2;

[0047] The HCDR3 sequence is SEQ ID NO: 3;

[0048] The LCDR1 sequence is SEQ ID NO: 35;

[0049] The LCDR2 sequence is SEQ ID NO: 5; and

[0050] The LCDR3 sequence is SEQ ID NO: 6; or

[0051] The HCDR1 sequence is SEQ ID NO: 1;

[0052] The HCDR2 sequence is SEQ ID NO: 2;

[0053] The HCDR3 sequence is SEQ ID NO: 3;

[0054] The LCDR1 sequence is SEQ ID NO: 37;

[0055] The LCDR2 sequence is SEQ ID NO: 5; and

[0056] The LCDR3 sequence is SEQ ID NO: 6; or

[0057] The HCDR1 sequence is SEQ ID NO: 1;

[0058] The HCDR2 sequence is SEQ ID NO: 2;

[0059] The HCDR3 sequence is SEQ ID NO: 3;

[0060] The LCDR1 sequence is SEQ ID NO: 43;

[0061] The LCDR2 sequence is SEQ ID NO: 5; and

[0062] The LCDR3 sequence is SEQ ID NO: 6; or

[0063] The HCDR1 sequence is SEQ ID NO: 1;

[0064] The HCDR2 sequence is SEQ ID NO: 2;

[0065] The HCDR3 sequence is SEQ ID NO: 3;

[0066] The LCDR1 sequence is SEQ ID NO: 4;

[0067] The LCDR2 sequence is SEQ ID NO: 5; and

[0068] The LCDR3 sequence is SEQ ID NO: 65; or

[0069] The HCDR1 sequence is SEQ ID NO: 1;

[0070] The HCDR2 sequence is SEQ ID NO: 68;

[0071] The HCDR3 sequence is SEQ ID NO: 3;

[0072] The LCDR1 sequence is SEQ ID NO: 37;

[0073] The LCDR2 sequence is SEQ ID NO: 5; and

[0074] The LCDR3 sequence is SEQ ID NO: 6 or

[0075] The HCDR1 sequence is SEQ ID NO: 1;

[0076] The HCDR2 sequence is SEQ ID NO: 2;

[0077] The HCDR3 sequence is SEQ ID NO: 29;

[0078] The LCDR1 sequence is SEQ ID NO: 35;

[0079] The LCDR2 sequence is SEQ ID NO: 5; and

[0080] The LCDR3 sequence is SEQ ID NO: 6.

[0081] In another preferred embodiment, the mutant bimagglutinin antibody comprises the variable heavy chain sequence shown in SEQ ID NO: 83.

[0082] In another preferred embodiment, the mutant bimagglutinumab comprises the variable light chain sequence shown in SEQ ID NO: 84.

[0083] In another preferred embodiment, the mutant bimagnumab comprises the following variable regions: a heavy chain variable region as shown in SEQ ID NO: 83 and a light chain variable region as shown in SEQ ID NO: 84.

[0084] In another preferred embodiment, the human antibody or its antigen-binding fragment comprises a constant region of human heavy chain IgG1.

[0085] In another preferred embodiment, the human heavy chain IgG1 constant region includes wild-type and mutant types.

[0086] In another preferred embodiment, the human heavy chain IgG1 constant region sequence is shown in SEQ ID NO: 89.

[0087] In another preferred embodiment, the Fc portion of the constant region of IgG1 is mutated at one or more amino acid positions to produce an antibody with significantly enhanced affinity for FCRN under acidic conditions.

[0088] In another preferred embodiment, the human antibody or its antigen-binding fragment contains a mutant sequence in the IgG Fc region.

[0089] In another preferred embodiment, the IgG Fc region mutation sequence has M311L and N317S mutations relative to the wild-type human heavy chain IgG1 constant region sequence.

[0090] In another preferred embodiment, the IgG Fc region mutation sequence contains G119N, H151D, A213K, M311L and N317S mutations relative to the wild-type human heavy chain IgG1 constant region sequence.

[0091] In another preferred embodiment, the IgG Fc region mutation sequence has an amino acid sequence selected from those shown in SEQ ID NO: 79-82.

[0092] In another preferred embodiment, the IgG Fc region mutation sequence is selected from the amino acid sequence shown in SEQ ID NO: 79 or 81.

[0093] In another preferred embodiment, the IgG Fc region mutation sequence is the amino acid sequence shown in SEQ ID NO: 81.

[0094] In a second aspect of the invention, an isolated nucleic acid molecule is provided that encodes the human antibody or antigen-binding fragment thereof described in the first aspect of the invention.

[0095] In a third aspect of the invention, an expression vector comprising the nucleic acid molecule described in the second aspect of the invention is provided.

[0096] In a fourth aspect of the invention, an isolated host cell comprising the expression vector described in the third aspect of the invention is provided.

[0097] In a fifth aspect of the invention, a method for producing a human antibody or an antigen-binding fragment thereof is provided, comprising culturing a host cell as described in the fourth aspect of the invention under conditions permissible for producing the antibody or fragment thereof, and recovering the antibody or fragment thereof thus produced.

[0098] In a sixth aspect of the invention, a pharmaceutical composition is provided, the pharmaceutical composition comprising:

[0099] (i) the human antibody or antigen-binding fragment thereof as described in the first aspect of the present invention; and

[0100] (ii) Pharmaceutically acceptable carriers.

[0101] In another preferred embodiment, the pharmaceutical composition is a liquid formulation.

[0102] In another preferred embodiment, the pharmaceutical composition is an injection.

[0103] In another preferred embodiment, the pharmaceutical composition further includes a GLP-1 receptor agonist, a Glucagon receptor agonist, and / or a GIP receptor agonist.

[0104] In another preferred embodiment, the GLP-1 receptor agonist is selected from the group consisting of smegglutinin, telpokinesin, or combinations thereof.

[0105] In another preferred embodiment, the pharmaceutical composition comprises 0.01 to 99.99% of an antibody or fragment thereof, or a combination thereof, of the first aspect of the present invention and 0.01 to 99.99% of a pharmaceutical carrier, wherein the percentages are percentages by mass of the pharmaceutical composition.

[0106] In a seventh aspect of the invention, the use of the human antibody or antigen-binding fragment thereof described in the first aspect of the invention, or the pharmaceutical composition described in the sixth aspect of the invention, is provided for the preparation of a medicament for treating lipid metabolism disorders and / or muscle atrophy-related diseases.

[0107] In another preferred embodiment, the lipid metabolism disorder includes: hyperlipidemia, hyperlipoproteinemia, and dyslipidemia, including atherosclerotic dyslipidemia, diabetic dyslipidemia, hypertriglyceridemia, including severe hypertriglyceridemia with TG > 1000 mg / dL, hypercholesterolemia, chylomicronemia, mixed dyslipidemia (obesity, metabolic syndrome, diabetes, etc.), lipid metabolism disorders, lipoatrophy, etc., preferably patients with hypercholesterolemia (HoFH), refractory hypercholesterolemia, and severe hypertriglyceridemia.

[0108] In another preferred embodiment, the muscle atrophy-related diseases include: muscular dystrophy, metabolic myopathy, neurogenic muscular atrophy, disuse atrophy, autoimmune myositis, anterior poliomyelitis, progressive muscular atrophy, amyotrophic lateral sclerosis, and myasthenia gravis.

[0109] It should be understood that, within the scope of this invention, the above-described technical features of this invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be described in detail here. Attached Figure Description

[0110] Figure 1 shows the weight changes in obese rhesus monkeys after drug administration in an embodiment of the present invention. Here, BW represents body weight.

[0111] Figure 2 shows the change in body fat percentage (BFR) in obese rhesus monkeys after drug administration relative to the pre-administration state in an embodiment of the present invention. Here, BFR represents body fat percentage.

[0112] Figure 3 shows the change in muscle mass in obese rhesus monkeys after drug administration relative to the pre-administration state in an embodiment of the present invention.

[0113] Figure 4 shows the blood drug concentration-time curves after the first and last doses in an embodiment of the present invention. Detailed Implementation

[0114] Through extensive and in-depth research, the inventors unexpectedly discovered for the first time that this invention preferably relates to the anti-ACVRII antibody bimagrumab or its biologically active variants and fragments, wherein the original bimagrumab antibody or its variants or fragments are engineered by mutations in the amino acid sequence within the variable region and the Fc fragment sequence. Specifically, this invention relates to bimagrumab or its biologically active variants or fragments, wherein the CDR domain is mutated by substituting one or more amino acid residues with histidine residues, and the Fc region is mutated by substituting multiple amino acids. The antibody of this invention has a longer half-life and stronger efficacy in vivo. Compared to intravenously administered bimagrumab, the antibody of this invention is suitable for subcutaneous administration due to the lower dosage required. This invention was completed based on this.

[0115] the term

[0116] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0117] The term “about” can refer to a value or composition within an acceptable range of error for a particular value or composition as determined by a person skilled in the art, which will depend in part on how the value or composition is measured or determined.

[0118] As used herein, the terms “containing” or “including (comprise)” can be open-ended, semi-closed, or closed. In other words, the terms also include “consistently made of” or “made of”.

[0119] Activin type II receptor (ACVRII)

[0120] Activin type II receptors (ACVRII, including ACVRIIA (or ACVR2A) and ACVRIIB (or ACVR2B)) are receptors in the transforming growth factor-β (TGF-β) superfamily, primarily involved in regulating cell growth, differentiation, metabolism, and tissue repair. Activin is one of the ligands of this receptor, binding to ACVRII to activate downstream signaling pathways (such as the SMAD pathway) and influencing various physiological functions. ACVR2A is widely expressed and participates in multiple biological processes. ACVR2B is mainly expressed in muscle and adipose tissue and is closely related to muscle growth and metabolic regulation. The amino acid sequences of human ACVR2A and human ACVR2B are shown in SEQ ID NO: 87 and SEQ ID NO: 88, respectively.

[0121] Bimagrumab

[0122] Bimagrumab acts on both ACVRIIA and B receptors, blocking Activin and MSTN signaling and regulating the activity of adipocytes and muscle cells. In adipocytes, Activin directly promotes lipid storage through ACVRII receptors, a key driver of visceral fat accumulation and obesity; while in muscle cells, the ACVRII receptor signaling pathway inhibits muscle growth and promotes atrophy. Bimagrumab can simultaneously block ACVRII signaling in both adipocytes and muscle cells, mobilizing and metabolizing fat, inhibiting muscle atrophy, and promoting muscle mass increase, helping obese patients improve body composition and metabolism while losing weight. The clinically used dose of the antibody Bimagrumab is very high (10-30 mg / kg), making subcutaneous injection unsuitable for high-dose administration and reducing patient convenience. The amino acid sequence of the CDR region of Bimagrumab is shown in Table 1. The protein sequences of the heavy and light chain variable regions of the Bimagrumab antibody are shown in SEQ ID NO: 85 and SEQ ID NO: 86, respectively.

[0123] Glucagon-like peptide-1 (GLP-1) receptor agonists

[0124] GLP-1 receptor agonists are an important class of drugs for lowering blood sugar and reducing weight, offering multiple advantages such as potent blood sugar reduction, weight loss, low risk of hypoglycemia, and cardiovascular protection. With ongoing research, their indications and clinical applications are continuously expanding. Smegglutide is a single GLP-1 receptor agonist with long-acting, dual effects of lowering blood sugar and reducing weight, and has been shown to have cardiovascular benefits. Telpopotide is a dual GLP-1 and GLP-1 receptor agonist, with even stronger effects on lowering blood sugar and reducing weight, but it is currently mainly used for type 2 diabetes; its use in obesity is still under investigation.

[0125] Glucagon receptor agonists

[0126] Glucagon receptor agonists are a class of drugs that regulate metabolism by activating glucagon receptors. Unlike GLP-1 receptor agonists, glucagon receptor agonists primarily affect blood glucose, energy metabolism, and body weight by mimicking the action of glucagon. Glucagon receptor agonists show great promise in the treatment of metabolic diseases, especially when used in combination with other drugs (such as GLP-1 receptor agonists), potentially achieving better therapeutic effects.

[0127] Glucose-dependent insulinotropic peptide (GIP) receptor agonists

[0128] GIP receptor agonists are a class of drugs that regulate metabolism by activating glucose-dependent insulinotropic peptide (GIP) receptors. GIP is an intestinal hormone, similar to GLP-1, and belongs to the incretin family. GIP receptor agonists affect blood glucose, energy metabolism, and body weight by mimicking the effects of GIP. Triple receptor agonists, such as LY3437943, simultaneously activate GIP, GLP-1, and Glucagon receptors, exhibiting a stronger metabolic regulatory effect.

[0129] The MWN109 of the present invention is a fatty acid chain modified polypeptide with GLP-1, Glucagon and GIP activities, a GLP-1 / Glucagon / GIP triple receptor agonist that can activate GLP-1 receptor, Glucagon receptor and GIP receptor, and has the effect of reducing body weight.

[0130] Preferably, the Bimagrumab variant of the present invention, when used in combination with MWN109, has a synergistic effect in reducing body weight.

[0131] Preferably, a pharmaceutical composition comprising the Bimagrumab variant of the present invention with a GLP-1 receptor agonist, a Glucagon receptor agonist, and / or a GIP receptor agonist may be used to treat lipid metabolism disorders and / or muscle atrophy-related diseases.

[0132] pH-dependent antibody of the present invention

[0133] As used herein, the terms "pH-dependent antibody of the present invention," "pH-dependent antigen-binding human antibody of the present invention," "antibody of the present invention," "mutated anti-ACVR2B antibody of the present invention," "Bimagrumab variant of the present invention," "mutated bimagrumab of the present invention," and "bimagrumab variant of the present invention" are used interchangeably to refer to the mutated bimagrumab in the first aspect of the present invention. It should be understood that the term also includes the ACVR2B antigen-binding fragment.

[0134] In vivo, antibody clearance of antigens primarily involves the antibody binding to the antigen, followed by endocytosis of the antibody-antigen complex within the cell. Inside the cell, the antibody-antigen complex is either degraded by lysosomes or, after binding to FcRn, carried to the cell surface and released extracellularly. Therefore, antibody binding to antigens is a one-time event. pH-dependent antibodies, on the other hand, are created by modifying the variable region of the antibody (mainly by replacing some amino acids in the antibody's CDR region with histidine), allowing the antibody to bind antigens at pH 7.2 (neutral environment) and release antigens at pH 6.0 (acidic lysosomal environment). When the pH-dependent antibody-antigen complex enters the lysosome, it is either degraded by the lysosome or, after release, degraded by the lysosome. The antibody then recycles to the extracellular space via FcRn. Extracellularly, the antibody can rebind to the antigen, thus allowing for multiple reuses and reducing the dosage of antibody drugs.

[0135] The recycling of pH-dependent antibodies requires the participation of FcRn. In this invention, the Fc region of the pH-dependent antibody is modified to enhance its affinity for FcRn, thereby enabling the pH-dependent antibody to have a dual recycling function and further prolonging the half-life of the pH-dependent antibody.

[0136] This invention includes not only complete antibodies, but also fragments of immunologically active antibodies or fusion proteins formed by antibodies and other sequences. Therefore, this invention also includes fragments, derivatives, and analogs of said antibodies. Preferably, it may contain a mutant sequence in the IgG Fc region. Preferably, the mutation improves the antibody half-life, thereby protecting such antibodies from nonspecific clearance. The IgG Fc region contains at least one mutation.

[0137] Enhancing the binding of IgG antibody Fc to FcRn can prolong its half-life. The binding of the IgG Fc region to FcRn is pH-dependent; it binds to FcRn with high affinity under acidic intracellular conditions and rapidly dissociates from FcRn under slightly alkaline conditions in the blood. This receptor-mediated recycling mechanism prolongs the half-life of IgG. The mutation sites M252Y, S254T, and T256E (called YTE) identified by MedImmune can extend the half-life of IgG in cynomolgus monkeys by nearly four times. In the acidic endosome environment, IgG antibodies can be captured by FcRn and circulate extracellularly, protecting this type of antibody from nonspecific clearance.

[0138] In some embodiments, IgG is a subclass of IgG1, IgG2, IgG3, or IgG4. In some embodiments, the Fc region is the Fc region of IgG; in some embodiments, the Fc region has one or more amino acid substitutions that enhance the binding of the Fc region to the Fc receptor. In some embodiments, the Fc region has G119N, H151D, A213K, M311L, and N317S mutations relative to the human heavy chain IgG1 constant region sequence (as shown in SEQ ID NO: 89), the mutations being numbered according to the EU index.

[0139] The pH-dependent antibody of this invention is based on the mutation and screening of Bimagrumab, and its Fc region is modified to further prolong its half-life, inhibit muscle atrophy and promote muscle mass increase, helping obese patients improve body composition and metabolism while losing weight, and providing obese patients with more effective and convenient treatment drugs.

[0140] The pH dependence of the Bimagrumab variant of the present invention corresponds to the ratio of the affinity constant (KD) for binding at pH 6 to the affinity constant for binding at pH 7.2.

[0141] Antibody

[0142] As used herein, the terms "antibody" or "immunoglobulin" refer to isotetraglycoproteins of approximately 150,000 Daltons with identical structural features, consisting of two identical light chains (L) and two identical heavy chains (H). Each light chain is linked to the heavy chain by a covalent disulfide bond, although the number of disulfide bonds between heavy chains varies among different immunoglobulin isotypes. Each heavy and light chain also has regularly spaced intrachain disulfide bonds. Each heavy chain has a variable region (VH) at one end, followed by multiple constant regions. Each light chain has a variable region (VL) at one end and a constant region at the other; the constant regions of the light chains are opposite the first constant region of the heavy chains, and the variable regions of the light chains are opposite the variable regions of the heavy chains. Specific amino acid residues form interfaces between the variable regions of the light and heavy chains.

[0143] As used herein, the term "variable" refers to the fact that certain portions of the variable region of an antibody differ sequentially, contributing to the binding and specificity of various specific antibodies to their specific antigens. However, variability is not uniformly distributed throughout the entire variable region of an antibody. It is concentrated in three segments within the variable regions of the light and heavy chains, known as complementarity-determining regions (CDRs) or hypervariable regions. The more conserved portions of the variable region are called framework regions (FRs). The variable regions of the native heavy and light chains each contain four FRs, which are generally β-sheet configurations linked by three CDRs forming a linking loop, and in some cases, partially β-sheet structures. The CDRs in each chain are tightly packed together by the FR regions and, together with the CDRs of the other chain, form the antigen-binding site of the antibody (see Kabat et al., NIH Publ. No. 91-3242, Vol. I, pp. 647-669 (1991)). Constant regions do not directly participate in antibody-antigen binding, but they exhibit different effector functions, such as participating in antibody-dependent cytotoxicity.

[0144] Vertebrate antibodies (immunoglobulins) can be classified into two distinct classes (denoted as κ and λ) based on the amino acid sequence of their constant region. Immunoglobulins can be further classified into different types based on the amino acid sequence of their heavy chain constant region. There are five main classes of immunoglobulins: IgA, IgD, IgE, IgG, and IgM, some of which can be further subdivided into subclasses (isotypes), such as IgG1, IgG2, IgG3, IgG4, IgA, and IgA2. The heavy chain constant regions corresponding to different classes of immunoglobulins are respectively called α, δ, ε, γ, and μ. The subunit structures and three-dimensional conformations of different classes of immunoglobulins are well known to those skilled in the art.

[0145] Generally, the antigen-binding properties of an antibody can be described by three specific regions located in the variable regions of the heavy and light chains, called variable regions (CDRs). These regions are divided into four frame regions (FRs). The amino acid sequences of the four FRs are relatively conserved and do not directly participate in the binding reaction. These CDRs form a ring structure, and are spatially close to each other through β-sheets formed by the FRs between them. The CDRs on the heavy chain and the corresponding CDRs on the light chain constitute the antigen-binding site of the antibody. The amino acid sequences of antibodies of the same type can be compared to determine which amino acids constitute the FR or CDR regions.

[0146] In this invention, the term "antigen-binding fragment" refers to a fragment with antigen-binding capability, and includes Fab, F(ab′), F(ab′)2, Fv, etc. In antibody fragments, Fab (antigen-binding fragment) has a structure containing a light chain variable region and a heavy chain variable region, a light chain constant region and a heavy chain first constant region (CH1), and has an antigen-binding site. Fab′ differs from Fab in that it has a hinge region including at least one cysteine ​​residue at the C-terminus of the heavy chain CH1 domain. In F(ab′)2 antibody, the cysteine ​​residues in the hinge region of Fab′ form disulfide bonds. Recombinant techniques for generating Fv fragments with minimal antibody fragment size are known in the prior art, where Fv only has heavy chain and light chain variable regions. Double-chain variable fragments (dcFv) are non-covalently linked to the heavy chain and light chain variable regions, while single-chain variable fragments (scFv) are typically covalently linked to the heavy chain variable region or C-terminus via peptide linkers to form dimers, such as double-chain Fv. These antibody fragments can be obtained using proteases (e.g., Fab can be obtained by cleaving an intact antibody with papain, while the F(ab′)2 fragment can be obtained by cleaving with pepsin), or they can be prepared using genetic recombination techniques.

[0147] In this invention, antibodies include mouse, chimeric, humanized, or fully human antibodies prepared using techniques well known to those skilled in the art. Recombinant antibodies, such as chimeric and humanized monoclonal antibodies, including both human and non-human portions, can be obtained using standard DNA recombination techniques and are all useful antibodies. A chimeric antibody is a molecule in which different portions are derived from different animal species, such as a chimeric antibody having a variable region derived from a mouse monoclonal antibody and a constant region derived from a human immunoglobulin (see, for example, U.S. Patents 4,816,567 and 4,816,397, which are incorporated herein by reference in their entirety). A humanized antibody is an antibody molecule derived from a non-human species, having one or more complementarity-determining regions (CDRs) derived from a non-human species and a framework region derived from a human immunoglobulin molecule (see U.S. Patent 5,585,089, which is incorporated herein by reference in its entirety). These chimeric and humanized monoclonal antibodies can be prepared using DNA recombination techniques well known in the art.

[0148] Unless otherwise specified, the amino acid positions within the antibody molecules according to the invention are based on Kabat numbering.

[0149] As used herein, an "antibody variant" or "monoclonal antibody variant" includes an antibody with a modified amino acid sequence compared to the parent antibody but with the same or altered binding affinity to the target antigen. Antibody variants differ from parent antibodies in that one or more amino acid residues are replaced, deleted, or added at specific positions within the variable domains (including the CDR domain) and / or constant regions of the antibody to modify certain properties of the antibody, such as binding affinity and / or receptor function, such as ADCC, FcRn binding, etc. Histidine-mutated antibodies of the present invention without further modification are not referred to as "antibody variants" according to the present invention. Antibody variants according to the present invention exhibit 80-99% sequence homology compared to the parent antibody, preferably 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, and 99% sequence homology, depending on the specific position of the amino acid residues to be replaced, deleted, or added.

[0150] In this invention, the antibody can be monospecific, bispecific, trispecific, or more multiple specific.

[0151] In this invention, the antibody also includes its conserved variants, which are polypeptides formed by replacing up to 10, preferably up to 8, more preferably up to 5, and most preferably up to 3 amino acids with amino acids of similar or analogous properties compared to the amino acid sequence of the antibody of this invention. These conserved variant polypeptides are preferably generated by amino acid substitutions according to Table A.

[0152] Table A

[0153] Pharmaceutical Composition

[0154] The present invention also provides a composition. In a preferred embodiment, the composition is a pharmaceutical composition containing the aforementioned antibody or its active fragment or fusion protein or its ADC or corresponding immune cell, and a pharmaceutically acceptable carrier. Typically, these substances are formulated in a non-toxic, inert, and pharmaceutically acceptable aqueous carrier medium, wherein the pH is typically about 5-8, preferably about 6-8, although the pH value may vary depending on the nature of the formulated substance and the condition to be treated.

[0155] The prepared pharmaceutical composition can be administered via conventional routes, including (but not limited to): intratumoral, intraperitoneal, intravenous, or local administration. Typically, the pharmaceutical composition of the present invention is preferably administered by injection or oral administration. Injection administration preferably includes intravenous injection, intramuscular injection, intraperitoneal injection, intradermal injection, or subcutaneous injection. The pharmaceutical composition is in various dosage forms conventional in the art, preferably in solid, semi-solid, or liquid form, and can be an aqueous solution, non-aqueous solution, or suspension, more preferably tablets, capsules, granules, injections, or infusions.

[0156] The antibody described in this invention can also be expressed in cells by a nucleotide sequence for cell therapy, such as for chimeric antigen receptor T-cell immunotherapy (CAR-T).

[0157] The pharmaceutical compositions of the present invention contain a safe and effective amount (e.g., 0.001-99 wt%, preferably 0.01-90 wt%, more preferably 0.1-80 wt%) of the above-described monoclonal antibody (or conjugate thereof) of the present invention, and a pharmaceutically acceptable carrier or excipient. Such carriers include (but are not limited to): saline, buffer, glucose, water, glycerol, ethanol, and combinations thereof. The pharmaceutical formulation should be matched to the route of administration. The pharmaceutical compositions of the present invention can be formulated into injectable forms, for example, prepared by conventional methods using physiological saline or an aqueous solution containing glucose and other excipients. Pharmaceutical compositions such as injections and solutions are preferably manufactured under sterile conditions. The dosage of the active ingredient is a therapeutically effective amount, for example, about 1 microgram per kilogram of body weight per day to about 5 milligrams per kilogram of body weight. Furthermore, the peptides of the present invention can also be used with other therapeutic agents.

[0158] Preferably, the pharmaceutical composition of the present invention further includes a GLP-1 class drug. The GLP-1 class drug is selected from the group consisting of smegglutide, telpoxetine, or combinations thereof.

[0159] In the embodiments of this invention, MWN109 is a fatty acid chain modified polypeptide with GLP-1, Glucagon, and GIP activities, capable of activating GLP-1 receptors, Glucagon receptors, and GIP receptors, and thus having a weight-reducing effect.

[0160] In this invention, preferably, the pharmaceutical composition further includes one or more pharmaceutical carriers. The pharmaceutical carrier is a conventional pharmaceutical carrier in the art, and can be any suitable physiologically or pharmaceutically acceptable pharmaceutical excipient. The pharmaceutical excipient is a conventional pharmaceutical excipient in the art, preferably including pharmaceutically acceptable excipients, fillers, or diluents. More preferably, the pharmaceutical composition comprises 0.01–99.99% of the above-mentioned protein and 0.01–99.99% of the pharmaceutical carrier, where the percentage is a percentage by mass of the pharmaceutical composition.

[0161] In this invention, preferably, the dosage of the pharmaceutical composition is an effective amount, which is an amount capable of alleviating or delaying the progression of a disease, degenerative or damaging condition. The effective amount can be determined on an individual basis and will be partly based on considerations of the symptoms to be treated and the desired outcome. Those skilled in the art can determine the effective amount by using the aforementioned factors, such as individual baselines, and by using experiments not exceeding the conventional range.

[0162] When using a pharmaceutical composition, a safe and effective amount of the immunoconjugate is administered to mammals. This safe and effective amount is typically at least about 10 micrograms per kilogram of body weight, and in most cases does not exceed about 50 milligrams per kilogram of body weight. Preferably, the dose is between about 10 micrograms per kilogram of body weight and about 20 milligrams per kilogram of body weight. Of course, the specific dosage should also take into account factors such as the route of administration and the patient's health condition, which are all within the scope of a skilled physician's expertise.

[0163] The main advantages of this invention include:

[0164] The antibody of this invention is a recyclable antibody that is pH dependent. At pH 6.0, the antibody binds less strongly to the antigen, while the antibody has a higher affinity for FcRn, a longer half-life in animals, requires a lower dosage, and has a better effect on fat loss and muscle gain.

[0165] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions as described in Sambrook et al., Molecular Cloning: A Laboratory Manual (New York: Cold Spring Harbor Laboratory Press, 1989), or as recommended by the manufacturer. Unless otherwise stated, percentages and parts are by weight.

[0166] Example 1: Design of CDR region mutant sequence and protein preparation of Bimagrumab

[0167] To obtain Bimagrumab variants with pH-dependent binding properties, a series of histidine mutant antibodies were constructed. The amino acid sequence of the CDR region of Bimagrumab is shown in Table 1, and the designed CDR region mutant sequences are shown in Table 2. Except for the mutated CDR region, the other sequences of the designed antibody sequences are consistent with the Bimagrumab sequence.

[0168] Table 1. CDR region sequence of Bimagrumab

[0169] Table 2. CDR region mutation sequences of Bimagrumab

[0170] The complete antibody sequences corresponding to the mutation sequences in Table 2 (for example, the antibody sequence numbered MWN110-07 means that, relative to the parental Bimagrumab antibody, the mutant antibody has HCDR2 as shown in SEQ ID NO: 12, and the rest of the sequence is consistent with the parental antibody) were constructed into the expression vector, and antibody proteins were prepared by transient expression for subsequent affinity assays to analyze the pH-dependent binding properties of the mutant antibody.

[0171] Example 2: Affinity determination of mutant antibodies at pH 7.2 and pH 6.0.

[0172] The difference in dissociation behavior at pH 6.0 or pH 7.2 after binding ACVR2B at pH 7.2 was evaluated using an initial Octet Red assay with immobilized antibodies. The KD values ​​of each histidine substitution variant anti-ACVR2B antibody bound to human ACVR2B at pH 7.2 (neutral) and pH 6.0 (acidic), and the corresponding pH 6.0 and pH 7.2 ratios, are shown in Table 3, with significant differences between the parental Bimagrumab antibody and the ratios.

[0173] Table 3. Affinity determination and ratio calculation of mutant antibodies

[0174] Example 3: Design of CDR region multi-point mutation and combinatorial mutation sequences and preparation of proteins

[0175] Based on the above CDR region mutation results, the following multi-point mutation and combination mutation sequences were designed (Table 4). The complete antibody sequences corresponding to the mutation sequences in Table 4 (for example, antibody sequence number MWN110-63 refers to the mutant antibody having LCDR1 as shown in SEQ ID NO: 35 and HCDR2 as shown in SEQ ID NO: 20, relative to the parental Bimagrumab antibody, while the remaining sequences are consistent with the parental antibody) were constructed into the expression vector. The antibody protein was prepared by transient expression and used for subsequent affinity assays to analyze the pH-dependent binding properties of the mutated antibody.

[0176] Table 4. CDR region mutation sequences

[0177] Example 4: Affinity determination of mutant antibodies at pH 7.2 and pH 6.0.

[0178] The difference in dissociation behavior at pH 6.0 or pH 7.2 after binding ACVR2A at pH 7.2 was evaluated using an initial Octet Red assay with immobilized antibodies. The KD values ​​of each histidine substitution variant anti-ACVR2A antibody bound to human ACVR2A at pH 7.2 (neutral) and pH 6.0 (acidic), and the corresponding pH 6.0 and pH 7.2 ratios, are shown in Table 5, with significant differences between the parental Bimagrumab antibody and the ratios.

[0179] Table 5. Affinity determination and ratio calculation of mutant antibodies

[0180] Example 5: Design and expression of mutant sequences in the Fc region of IgG

[0181] Based on the mutation results of the CDR region, the Fc region mutation sequences (Table 6) were designed as shown in the table below. The sequences (Fc1-Fc4) in the table below were combined with the variable region and hinge region sequences of the MWN110-74 or MWN110-83 antibody mentioned above to form complete antibody sequences. Antibody proteins were prepared by transient expression and used for subsequent affinity assays to analyze the pH-dependent binding properties of the mutated antibody.

[0182] Table 6. Mutant sequences in the Fc region of IgG

[0183] Example 6: Affinity determination of IgG Fc region mutant antibody at pH 7.2 and pH 6.0.

[0184] The difference in dissociation behavior at pH 6.0 or pH 7.2 after binding ACVR2B at pH 7.2 was evaluated using an initial Octet Red assay with immobilized antibodies. The KD values ​​of each IgG Fc region mutant anti-ACVR2B antibody binding to human ACVR2B at pH 7.2 (neutral) and pH 6.0 (acidic), and the corresponding pH 6.0 and pH 7.2 ratios, are shown in Table 7.

[0185] Table 7. Affinity determination and ratio calculation of IgG Fc region mutant antibodies

[0186] The results showed that compared with MWN110-74 or MWN110-83 without Fc amino acid mutations, mutating the Fc amino acid to Fc1 (as shown in SEQ ID NO: 79) or Fc3 (as shown in SEQ ID NO: 81) significantly increased the KD ratio at pH 6.0 and pH 7.2, by more than 70-fold, with the Fc3 mutation being more effective than the Fc mutation. Specifically, the KD ratios (KD(6.0) / KD(7.2)) of MWN110-117 and MWN110-121 at pH 6.0 and pH 7.2 were 1100.48 and 1195.12, respectively, which were 353.85-fold and 384.28-fold higher than that of Bimagrumab. Therefore, Fc amino acid mutation significantly increased the KD ratio at pH 6.0 and pH 7.2, exhibiting a synergistic increase in the ratio and also increasing the possibility of mutated antibody recycling.

[0187] Example 7: Affinity of IgG Fc region mutant antibody to recombinant human and monkey FCRN was determined at pH 7.2 and pH 6.0.

[0188] The purpose of the IgG Fc region mutant antibody is to enhance the antibody's affinity for FCRN under acidic conditions (pH 6.0) without altering the binding and dissociation of the antibody with FCRN under neutral conditions (pH 7.2) and without affecting the antibody's ability to bind to the antigen. In the previous example, it was evaluated that the antibody-antigen binding was unaffected. This application will evaluate the affinity of the mutant antibody for recombinant human and monkey FCRN. The results are shown in Table 8. The MWN110-117 and MWN110-121 antibodies showed significantly stronger affinity for FCRN than the parent antibody Bimagrumab under acidic conditions (pH 6.0).

[0189] Table 8. Affinity determination of IgG Fc region mutant antibodies with FCRN from different species

[0190] Example 8: Affinity determination of IgG Fc region mutant antibody with recombinant human FcγRIIIa

[0191] FcγRIIIa is a key receptor that causes ADCC. This invention will evaluate the affinity of IgG Fc region mutant antibodies for recombinant human FcγRIIIa.

[0192] The results are shown in Table 9. Under neutral conditions, the parental antibody Bimagrumab has a strong affinity for recombinant human FcγRIIIa, which may have an ADCC effect; while MWN110-117 and MWN110-121 do not bind to recombinant human FcγRIIIa, which may not have an ADCC effect.

[0193] Table 9. Affinity determination of IgG Fc region mutant antibody with recombinant human FcγRIIIa

[0194] Example 9 Animal Pharmacodynamics and Pharmacokinetics Experiment

[0195] The pharmacokinetic (PK) parameters of MWN110-117 were evaluated in obese rhesus monkeys, and the effects of MWN110-117 alone or in combination with MWN109 (MWN109 is a fatty acid chain-modified polypeptide with GLP-1, Glucagon, and GIP activities, capable of activating GLP-1, Glucagon, and GIP receptors, and having a weight-reducing effect) on animal body weight, body fat, and muscle mass were assessed and compared with Bimagrumab. Rhesus monkeys with a body fat percentage >20% and abnormal glucose and lipid metabolism for more than one year were selected as experimental animals. After grouping by body weight, body fat and muscle mass were measured before administration. Subcutaneous injection was administered once weekly for 8 weeks. At the end of the administration period, body fat and muscle mass were measured. Additionally, blood samples were collected after the first and last administrations to measure drug concentration and determine PK parameters. The experimental groups are shown in Table 10 below.

[0196] Table 10 Grouping of Obese Rhesus Monkeys in Experiments

[0197] The results showed that, as shown in Figure 1, Bimagrumab and different doses of MWN110-117 alone had little effect on animal body weight. However, the combination of MWN110-117 and MWN109 resulted in a greater decrease in body weight (BW) at week 8 (day 56) than MWN109 alone, indicating a synergistic effect in reducing body weight.

[0198] As shown in Figure 2, compared to pre-administration levels, the placebo group showed minimal change in body fat percentage (BFR) after administration. The Bimagrumab group, and the groups using MWN110-117 alone or in combination, all showed significant decreases in BFR. The mean difference in BFR reduction between MWN110-117 (3 mg / kg) and Bimagrumab (10 mg / kg) was small, while the reduction in BFR with MWN110-117 (10 mg / kg) was greater than that with the same dose of Bimagrumab. These results indicate that, under the same dosage conditions, MWN110-117 of this invention significantly reduces body fat percentage more effectively than Bimagrumab. Furthermore, compared to MWN109 alone, the combination of MWN110-117 and MWN109 resulted in a greater reduction in body fat percentage. Therefore, MWN110-117, when used in combination with drugs possessing GLP activity (such as MWN109), exhibits a synergistic lipid-lowering effect.

[0199] As shown in Figure 3, compared with before drug administration, the changes in muscle weight in the placebo group and the MWN109 group were relatively small after drug administration, while the muscle weight in the Bimagrumab group and the MWN110-117 single or combined groups increased significantly. The mean difference in the increase rate between MWN110-117 (3 mg / kg) and Bimagrumab (10 mg / kg) was small, but the increase rate of MWN110-117 (10 mg / kg) was greater than that of the same dose of Bimagrumab. The results indicate that, under the same dosage conditions, MWN110-117 of the present invention significantly outperforms Bimagrumab in increasing muscle weight. Therefore, MWN110-117 of the present invention has a significant fat-reducing and muscle-building effect.

[0200] After the first administration, the blood drug concentration at each blood collection point was measured, and the p-value was calculated. The results are shown in Table 11 and Figure 4.

[0201] Table 11 PK parameters in animals after first administration

[0202] The results showed that the half-life of MWN110-117 of the present invention is 3.5 times that of Bimagrumab. The AUC of an equivalent dose of MWN110-117 after the last administration was... 0-168 It is significantly longer than Bimagrumab. Therefore, MWN110-117 of the present invention has a longer half-life.

[0203] The amino acid sequence of the mutant antibody (MWN110-117 antibody) of the present invention from the N-terminus to the C-terminus is as follows:

[0204] MWN110-117 antibody heavy chain variable region protein sequence: SEQ ID NO: 83

[0205] MWN110-117 antibody light chain variable region protein sequence: SEQ ID NO: 84

[0206] Bimagrumab antibody heavy chain variable region protein sequence: SEQ ID NO: 85

[0207] Bimagrumab antibody light chain variable region protein sequence: SEQ ID NO: 86

[0208] Amino acid sequence of human ACVR2A: SEQ ID NO: 87

[0209] Amino acid sequence of human ACVR2B: SEQ ID NO: 88

[0210] Human heavy chain IgG1 constant region sequence: SEQ ID NO: 89

[0211] All documents mentioned in this invention are incorporated herein by reference as if each document were individually incorporated by reference. Furthermore, it should be understood that after reading the foregoing teachings of this invention, those skilled in the art can make various alterations or modifications to this invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A human antibody or antigen-binding fragment thereof with pH-dependent antigen binding, characterized in that, It comprises a light chain variable region and a heavy chain variable region of bismagnumab or a variant thereof having the same or similar biological activity, wherein at least one CDR domain of the light chain variable region and / or the heavy chain variable region is mutated by substituting one or more amino acids within the CDR domain with histidine residues, thereby producing a mutated bismagnumab or a bismagnumab variant that induces pH-dependent antigen binding, wherein, The mutated bismagnumab was measured by Biolayer Interferometry, and the ratio of its affinity constant (KD) to that of the antigen at pH 6 to pH 7.2 was determined as K1. The ratio of the affinity constant of the non-mutated bismagnumab to the antigen at pH 6 to that of pH 7.2 was determined as K0, where K1 / K0 is r, and r ≥ 1.

3.

2. The human antibody or antigen-binding fragment thereof with pH-dependent antigen binding as described in claim 1, characterized in that, The human antibody refers to the humanized anti-ACVR2B antibody.

3. The human antibody or antigen-binding fragment thereof with pH-dependent antigen binding as described in claim 1, characterized in that, The binding fragment includes sequences selected from the following group, with the remaining sequences being identical to the CDR region sequence of the non-mutated bimagglutinumab: HCDR1, as shown in SEQ ID NO: 7 or SEQ ID NO: 8, HCDR2 as shown in SEQ ID NO: 12, 13, 16, 17, 20, 21, 24, 25, 26, 28, 67, 68 or 70, HCDR3, as shown in SEQ ID NO: 29, 30, 33 or 34, LCDR1 as shown in SEQ ID NO: 35, 36, 37, 39, 40, 42, 43, 44, 45, 47, 73, 74, 75, 76 or 78, LCDR2 as shown in SEQ ID NO: 49, 52, 53 or 55, LCDR3 as shown in SEQ ID NO: 56, 58, 59, 61, 62, 63, 64 or 65, or a combination thereof.

4. The human antibody or antigen-binding fragment thereof with pH-dependent antigen binding as described in claim 1, characterized in that, The human antibody or its antigen-binding fragment contains a mutant sequence in the IgG Fc region, wherein the mutant sequence in the IgG Fc region has M311L and N317S mutations relative to the constant region sequence of wild-type human heavy chain IgG1.

5. An isolated nucleic acid molecule encoding the human antibody or antigen-binding fragment thereof as described in claim 1.

6. An expression vector comprising the nucleic acid molecule of claim 5.

7. An isolated host cell comprising the expression vector of claim 6.

8. A method for producing human antibodies or antigen-binding fragments thereof, characterized in that, This includes culturing the host cells as described in claim 7 under conditions that allow for the production of the antibody or a fragment thereof, and recovering the antibody or a fragment thereof thus produced.

9. A pharmaceutical composition, characterized in that, The pharmaceutical composition contains: (i) the human antibody or antigen-binding fragment thereof as claimed in claim 1; and (ii) Pharmaceutically acceptable carriers.

10. Use of the human antibody of claim 1 or its antigen-binding fragment, or the pharmaceutical composition of claim 9, for the preparation of a medicament for the treatment of lipid metabolism disorders and / or muscle atrophy-related diseases.

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