METHOD FOR TREATING MEMBRANOUS NEPHROPATHY WITH TACI-FC FUSION PROTEIN

[0001] The present disclosure relates to a TACI-Fc fusion protein drug for treating membranous nephropathy, and a dosage regimen, a dosing interval and an administration mode thereof.

[0002] Membranous nephropathy (MN) is an antibody-mediated glomerular disease, which is characterized by the formation of immune deposits containing antigens, IgG and complement components beneath epithelial cells of glomerular capillary loops. The sublethal injury of epithelial cells leads to cellular simplification and disruption of glomerular filtration barrier, resulting in proteinuria and other manifestations of nephrotic syndrome.

[0003] Clinically, membranous nephropathy can be divided into primary membranous nephropathy and secondary membranous nephropathy according to the etiology. The majority of membranous nephropathies are categorized as primary membranous nephropathies, also called as idiopathic membranous nephropathies, which is an organ-specific autoimmune disease that occurs in the absence of any identified cause or initiating event. About 20-30% of membranous nephropathies are categorized as secondary membranous nephropathies. Common causes include autoimmune diseases (e.g., lupus), viruses (e.g., hepatitis B virus, hepatitis C virus or syphilis), tumors, certain drugs (e.g. analgesics), toxins (e.g. exposure to heavy metals such as lead and mercury) and the like. Membranous nephropathy is one of the most common causes of nephrotic syndrome in non-diabetic adults, accounting for up to one-third of biopsy results of nephrotic syndrome cases. Its main clinical symptoms are oedema, proteinuria, hypoalbuminemia, hyperlipidemia, and the like, which mainly affects the function of glomerular basement membrane, and also increases the risk of thrombosis, infection, cardiovascular disease and the like.

[0004] Currently, the global incidence of membranous nephropathy is approximately 1 case per 100,000 people per year. It remains unclear whether the incidence of membranous nephropathy varies by region or ethnicity, however, it can be confirmed that membranous nephropathy can occur in patients of all ages and ethnicities. In the United States, the incidence of membranous nephropathy is approximately 12 cases per million individuals per year, with an average onset age between 50 and 60 years. In China, the incidence of membranous nephropathy has been increasing over the past 20 years, and other studies have suggested that the high incidence of membranous nephropathy may be associated with worsening air pollution. According to statistics, among these patients with membranous nephropathy, nearly 60% of those who have not been treated for a long term have a decrease in kidney function, and 30-40% of them will eventually progress to end-stage renal disease within 10 years. Even being treated with immunosuppressants, 20%-40% of patients still show persistent heavy proteinuria during the course of the disease and will progress to end-stage renal disease within 10 years, which requires renal replacement or transplantation therapy.

[0005] The treatment of membranous nephropathy depends on its type and etiology. Currently, the treatment of membranous nephropathy mainly includes the following treatment methods: (1) conventional therapy: if the quantification of the 24-hour urine protein of the patient with membranous nephropathy is less than 3.5 g; or between 3.5 g and 8 g and the renal function is normal and there is no high-risk phenomenon, pril drugs and sartan drugs are usually used to reduce urine protein, and supportive therapy, such as diuresis, antihypertensive and anticoagulant treatment, is also given; (2) combination of hormone and immunosuppressant: if the quantification of the 24-hour urine protein of the patient with membranous nephropathy is greater than 3.5 g accompanied by renal function decrease; or the urine protein is greater than 8 g, a combination therapy of hormone and immunosuppressant is adopted for treatment; and (3) monoclonal antibody drugs (such as rituximab).

TABLE 1
Treatment regimens for membranous nephropathy
recommended in 2021 KDIGO Guideline
Cyclophosphamide	Intravenous injection of methylprednisolone 1 g for 3 consecutive days in
(cyclical	the first few days of the 1st, 3rd, and 5th month,
administration)	Oral prednisone 0.5 mg/kg/day,
	Oral cyclophosphamide 2.5 mg/kg body weight/day in the 2nd, 4th and
	6th month
Cyclophosphamide	Intravenous injection of methylprednisolone 1 g for 3 consecutive days in
(continuous	the first few days of the 1st , 3rd, and 5th month,
administration)	Oral prednisone 0.5 mg/kg every other day, for 1-6 months, then gradually
	tapered,
	Oral cyclophosphamide 1.5 mg/kg body weight/day for 16 months
Rituximab	Rituximab 1000 mg IV twice within 2 weeks
	Rituximab 375 mg/m2 body surface area weekly, total 1-4 times
Tacrolimus	Tacrolimus 0.05-0.1 mg/kg body weight/day, aiming at 3-8 ng/ml blood
	drug concentration maintained for 12 months
Cyclosporine	Cyclosporine 3.5 mg/kg body weight/day, aiming at 125-225 mg/ml blood
	drug concentration

[0006] The 2021 KDIGO Guideline recommend five treatment regimens for membranous nephropathy (see Table 1), which are cyclophosphamide in cyclical administration or continuous administration, rituximab, tacrolimus and cyclosporine, respectively. Wherein: 1) the cyclical or continuous administration of cyclophosphamide must be combined with the administration of hormonal drugs (e.g., prednisone), while hormonal drugs have significant side effects and cyclophosphamide has also adverse reactions such as reproductive toxicity, myelosuppression, infection and hemorrhagic cystitis. Moreover, from the perspective of application reality, after treating using the hormone+cyclophosphamide regimen, there are still nearly half of the patients cannot be relieved, and once the patients who get relief stop taking the drug, the disease is likely to relapse. (2) Tacrolimus and cyclosporine are calcineurin inhibitors (CNIs), which belong to a broad category of immunosuppressive drugs. For patients who are unwilling to receive glucocorticoid+cyclophosphamide therapy or have contraindications to treatment, CNIs can be used for treatment. Wherein, the cyclosporine therapy has the advantage of rapid onset of action, with better efficacy and fewer and milder adverse effects compared to cyclophosphamide. Its disadvantages include an overall remission rate no higher than that of cyclophosphamide regimen and a significantly higher short-term recurrence rate compared to cyclophosphamide. Although the immunosuppressive potency of tacrolimus is 10-100 times higher than that of cyclosporine, it also has similar shortcomings to cyclosporine, i.e., tacrolimus also has the problem of a high recurrence rate. Additionally, a prominent adverse effect of tacrolimus is that it leads to abnormal glucose tolerance and new-onset diabetes. (3) Currently, rituximab alone or in combination with a calcineurin inhibitor is recommended for the initial treatment of primary membranous nephropathy with intermediate, high, or very high risk, with a remission rate of 67% for membranous nephropathy. In addition, rituximab is applicable for patients with membranous nephropathy who are either positive or negative for anti-PLA2R antibodies. However, rituximab is expensive, has a low patient accessibility, and has severe infusion reactions. Various studies have reported that the incidence of infusion-related reactions associated with rituximab ranges from 26% to 85%, and in patients with hematological neoplasms, rare adverse events such as reactivation of hepatitis B virus and severe skin reactions (e.g., toxic epidermal necrolysis and Stevens-Johnson syndrome) caused by rituximab have also been reported (Reference 1: Alsharhan L, Beck L H Jr. Membranous Nephropathy: Core Curriculum 2021. Am J Kidney Dis.2021 March; 77 (3): 440-453). In general, the clinical course of membranous nephropathy is often indolent, and existing treatments are toxic. Existing treatment options have certain limitations and risks, and their therapeutic effects are not always satisfactory. However, from the clinical application perspective, if the combination therapy of hormone and immunosuppressant is ineffective, monoclonal antibody drugs (such as rituximab) are usually used for treatment. Therefore, the development of new biological drugs (e.g. monoclonal antibody drugs) has become an urgent need for the treatment of membranous nephropathy.

TABLE 2
Biological drugs approved and in Phase III clinical
trial for treating membranous nephropathy
			Highest research and
Drug name	Target	Research institute	development stage
Rituximab	CD20	Roche	Approved for marketing
Obinutuzumab	CD20	Glycart	Approved for marketing
		Biotechnology
		(Roche)
MIL62	CD20	Mabworks	Clinical phase III
Felzartamab	CD38	TJ Biopharma	Clinical phase III

[0007] As of Sep. 22, 2022, only two biological drugs for membranous nephropathy have been approved for marketing in the world, which are rituximab and obinutuzumab, respectively. In addition, there are two other drugs in phase III clinical research stage (see Table 2). Among these drugs, although rituximab was included in the recommended treatment regimen for membranous nephropathy of KDIGO Guidelines in 2021, it still faces problems such as a low remission rate, high infusion reactions, severe adverse reactions and a high price. Although obinutuzumab, which also targets CD20, can achieve certain therapeutic effects on patients with membranous nephropathy who have failed treatments clinically, the relevant therapeutic effect is only partial remission rather than complete remission, because it cannot completely eliminate antibodies and immune complexes, the basement membrane of the kidney is still damaged, and some urine protein will still leak out. In addition, as obinutuzumab is more cytotoxic compared to rituximab and has a stronger ability to consume B cells, it may face greater challenges in terms of adverse reactions (Reference 2: Hudson R, Rawlings C, Mon SY, et al. Treatment resistant M-type phospholipase A2 receptor associated membranous nephropathy responds to obinutuzumab: a report of two cases. BMC Nephrol. 23,134 (2022)). Therefore, there is a huge unmet clinical need in the field of membranous nephropathy treatment, both in China and globally.

[0008] The present disclosure discovers a TACI-Fc fusion protein having significant therapeutic effects in treating patients with membranous nephropathy.

[0009] Specifically, the present disclosure provides a method of treating membranous nephropathy, and the method comprises administering a therapeutically effective amount of a TACI-Fc fusion protein to a patient with membranous nephropathy.

[0010] Specifically, the present disclosure further provides a method of treating a patient with membranous nephropathy who has already received a treatment regimen for membranous nephropathy, and the method comprises (1) determining whether the patient has already received a treatment regimen for membranous nephropathy, and (2) if that the patient has previously received a treatment for membranous nephropathy, administering a therapeutically effective amount of a TACI-Fc fusion protein to the patient with membranous nephropathy.

[0011] Specifically, the present disclosure further provides use of a TACI-Fc fusion protein in the manufacture of a medicament for treating a patient with membranous nephropathy.

[0012] Further, the TACI-Fc fusion protein described in any one of the foregoing items comprises (i) a TACI extracellular region or a fragment thereof binding to Blys and/or APRIL; and (ii) a fragment of human immunoglobulin constant region.

[0013] In one embodiment, the TACI extracellular region or the fragment thereof comprises an amino acid sequence set forth in SEQ ID NO: 1.

SEQ ID NO: 1
SRVDQEERFP QGLWTGVAMR SCPEEQYWDP LLGTCMSCKT ICNHQSQRTC AAFCRSLSCR	60
KEQGKFYDHL LRDCISCASI CGQHPKQCAY FCENKLRSPV NLPPEL	106

[0014] In one embodiment, the human immunoglobulin is IgG1.

[0015] Further, the fragment of human immunoglobulin constant region comprises an amino acid sequence set forth in SEQ ID NO: 2 or an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to SEQ ID NO: 2.

SEQ ID NO: 2
DKPHTCPLCP APELLGGPSV FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVKFNWYVD	60
GVEVHNAKTK PREEQYNSTY RVVSVLTVLH QDWLNGKEYK CKVSNKALPA PIEKTISKAK	120
GQPREPQVYT LPPSRDELTK NQVSLTCLVK GFYPSDIAVE WESNGQPENN YKATPPVLDS	180
DGSFFLYSKL TVDKSRWQQG NVFSCSVMHE ALHNHYTQKS LSLSPGK	227

[0016] Further, the fragment of human immunoglobulin constant region comprises one or more modifications of amino acid at positions 3, 8, 14, 15, 17, 110, 111 or 173 of SEQ ID NO: 2.

[0017] Further, the modification is substitution, deletion or insertion of an amino acid.

[0018] Further, the substitution is selected from the group consisting of P3T, L8P, L14A, L15E, G17A, A110S, P111S and A173T.

[0019] In one embodiment, the fragment of human immunoglobulin constant region comprises an amino acid sequence set forth in SEQ ID NO: 3.

SEQ ID NO: 3
DKTHTCPPCP APEAEGAPSV FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVKFNWYVD	60
GVEVHNAKTK PREEQYNSTY RVVSVLTVLH QDWLNGKEYK CKVSNKALPS SIEKTISKAK	120
GQPREPQVYT LPPSRDELTK NQVSLTCLVK GFYPSDIAVE WESNGQPENN YKTTPPVLDS	180
DGSFFLYSKL TVDKSRWQQG NVFSCSVMHE ALHNHYTQKS LSLSPGK	227

[0020] In one embodiment, the TACI-Fc fusion protein has an amino acid sequence set forth in SEQ ID NO: 4.

SEQ ID NO: 4
SRVDQEERFP QGLWTGVAMR SCPEEQYWDP LLGTCMSCKT ICNHQSQRTC AAFCRSLSCR	60
KEQGKFYDHL LRDCISCASI CGQHPKQCAY FCENKLRSPV NLPPELDKTH TCPPCPAPEA	120
EGAPSVFLFP PKPKDTLMIS RTPEVTCVVV DVSHEDPEVK FNWYVDGVEV HNAKTKPREE	180
QYNSTYRVVS VLTVLHQDWL NGKEYKCKVS NKALPSSIEK TISKAKGQPR EPQVYTLPPS	240
RDELTKNQVS LTCLVKGFYP SDIAVEWESN GQPENNYKTT PPVLDSDGSF FLYSKLTVDK	300
SRWQQGNVFS CSVMHEALHN HYTQKSLSLS PGK	333

[0021] In one embodiment, the TACI-Fc fusion protein is telitacicept.

[0022] Further, the TACI-Fc fusion protein is administered at a single dose of about 0.1 to 10 mg/kg, further including 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.6, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.7, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.8, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.9, 9.6, 9.7, 9.8, 9.9 and 10 mg/kg.

[0023] Further, the TACI-Fc fusion protein is administered at a single dose of 160 to 240 mg, further preferably 160 mg, 170 mg, 180 mg, 190 mg, 200 mg, 210 mg, 220 mg, 230 mg or 240 mg.

[0024] Further, a method for detecting the content of the above fusion protein is UV-visible spectrophotometry, wherein according to the fact that the protein has a maximum UV absorption at 280 nm, the absorbance value of the telitacicept sample is measured at this wavelength. After correcting the absorbance at 320 nm, the absorbance value measured at 280 nm is proportional to the protein concentration, and the protein concentration is calculated according to Lambert-Beer law to determine the protein content. The formula for calculating the protein content is as follows:

$\mathrm{Protein}\mathrm{content}\left(\mathrm{mg}/\mathrm{ml}\right)=\left(\mathrm{or}\left(\mathrm{corrected}\right)\right)*\mathrm{sample}\mathrm{dilution}\mathrm{multiple}$

[0025] In the formula, & represents the extinction coefficient value of telitacicept in (mg/ml)⁻¹·cm⁻¹. A280 represents the average value of absorbance of sample solutions at 280 nm. A₂₈₀ (corrected) represents the average value of absorbance of sample solutions at 280 nm after correction.

[0026] Further, the TACI-Fc fusion protein is administered 2-4 times at an interval of one month. That is, the administration frequency of the TACI-Fc fusion protein is 2 times per month or 3 times per month or 4 times per month.

[0027] Further, the TACI-Fc fusion protein is administered at a frequency of once a week.

[0028] In one embodiment, the administration lasts for about 2 to 50 weeks. In a further embodiment, the administration lasts for 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, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49 or 50 weeks.

[0029] In one embodiment, the TACI-Fc fusion protein is administered subcutaneously, intramuscularly or intravenously, at a position of preferably thigh, abdomen or upper arm. In some specific embodiments, the TACI-Fc fusion protein is administered by subcutaneous, intramuscular or intravenous injection.

[0030] In one embodiment, the TACI-Fc fusion protein is injected at the same site or at different sites per injection. In some specific embodiments, the TACI-Fc fusion protein is injected at the same site per injection. In some other specific embodiments, the TACI-Fc fusion protein is injected at different sites per injection.

[0031] Further, the membranous nephropathy is primary membranous nephropathy or

[0032] secondary membranous nephropathy.

[0033] Further, the membranous nephropathy is PLA2R-positive or PLA2R-negative.

[0034] Further, the patient is an adult patient or a child patient.

[0035] Further, the patient has previously received a treatment regimen for membranous nephropathy.

[0036] Further, the treatment regimen for membranous nephropathy includes conventional therapy of membranous nephropathy, combination therapy of hormone and immunosuppressant, and monoclonal antibody drugs therapy.

[0037] Further, the treatment regimen for membranous nephropathy includes: cyclical administration of cyclophosphamide in combination with a hormone drug to the patient, or continuous administration of cyclophosphamide in combination with a hormone drug to the patient, or administration of tacrolimus to the patient, or administration of cyclosporine to the patient, or administration of rituximab to the patient, or administration of obinutuzumab to the patient, or administration of MIL62 to the patient, or administration of felzartamab to the patient.

[0038] The TACI-Fc fusion protein provided by the present disclosure shows satisfactory clinical effects and a good safety in the treatment of patients with membranous nephropathy.

[0043] Unless otherwise defined, all scientific terms used herein have the same meaning as commonly understood in the art. For definitions and terms in the art, specific reference to Current Protocols in Molecular Biology (Ausubel) is made.

[0044] The three-letter codes and one-letter codes of amino acids used in the present disclosure are as described in J. biol. chem, 243, p3558 (1968).

[0045] The term “TACI” in the present disclosure refers to transmembrane activator and CAML interactor, which is a member of the tumor necrosis factor receptor superfamily. The term “BLys” in the present disclosure refers to B lymphocyte stimulator, which is a member of the TNF ligand superfamily existing in two forms of membrane-bound and soluble forms, specifically expressed on the surface of bone marrow cells, and selectively stimulates the proliferation of B lymphocytes and the production of immunoglobulin. The term “APRIL” (a proliferation-inducing ligand) in the present disclosure refers to a tumor necrosis factor (TNF) analogue, which can stimulate the proliferation of primitive B cells and T cells in the body, promote the accumulation of B cells and increase their content in spleen. APRIL can specifically bind to TACI and BCMA, and the binding can prevent APRIL from binding to B cells and thus inhibit the proliferative response of primitive B cells stimulated by APRIL. Moreover, APRIL can compete with BLys for binding to receptors (BCMA and TACI).

[0046] The term “TACI-Fc fusion protein” involved in the present disclosure refers to transmembrane activator, calcium regulator and cyclophilin ligand interactor (TACI)-immunoglobulin fusion protein (i.e., TACI-Fc fusion protein). The TACI-immunoglobulin fusion protein provided by the present disclosure comprises: (i) a TACI extracellular region or a fragment thereof binding to Blys and/or APRIL; and (ii) a fragment of human immunoglobulin constant region.

[0047] For the term “TACI extracellular region or a fragment thereof binding to Blys and/or APRIL”, specific reference can be made to the TACI extracellular domain and the specific fragment of TACI extracellular domain capable of interacting with TACI ligands disclosed in U.S. Pat. Nos. 969,102, 6,316,222 and 6,500,428 and U.S. patent application Ser. Nos. 09/569,245 and 09/627,206, the contents of which are incorporated herein by reference, or the fragment of amino acids 13-118 of TACI extracellular domain disclosed in Chinese Patent Publication No. CN101323643A.

[0048] In the term “fragment of human immunoglobulin constant region”, the immunoglobulin is preferably IgG1, which may comprise a heavy chain constant region, for example, heavy chain constant region of human. The preferred “fragment of human immunoglobulin constant region” of the present disclosure is an amino acid fragment comprising a portion of the hinge region domain, a CH2 domain and a CH3 domain. In some more embodiments, the “fragment of human immunoglobulin constant region” described in the present disclosure has an amino acid sequence set forth in SEQ ID NO: 2, or an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity to SEQ ID NO: 2. In some more embodiments, the “fragment of human immunoglobulin constant region” has an amino acid sequence set forth in SEQ ID NO:3.

[0049] The term “treatment” involved in the present disclosure is related to a given disease or condition, including but not limited to: inhibiting the disease or condition, for example, preventing the development of the disease or condition; alleviating the disease or condition, for example, causing the regression of the disease or condition; or ameliorating the symptoms caused by the disease or condition, for example, alleviating, preventing or treating the symptoms of the disease or condition.

[0050] The term “amino acid” involved in the present disclosure is understood in the broadest sense, and it is a general term for a class of organic compounds containing amino and carboxyl. In one embodiment, the amino acid involved in the present disclosure is the main unit of proteins constituting living organisms, which includes, but is not limited to: glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine and histidine.

[0051] The three-letter codes and one-letter codes of amino acids used in the present disclosure are as described in J. biol. chem, 243, p3558 (1968). There are many ways of numbering amino acid positions, such as Kabat numbering system, EU numbering system, and sequence numbering. In the present disclosure, the amino acid positions are numbered using “sequence numbering”, for example, the “position 3, 8, 14, 15, 17, 110, 111 or 173 of SEQ ID NO: 2” in the present disclosure refers to the 3rd amino acid, the 8th amino acid, and so on of SEQ ID NO: 2. For example, the “P3T” in the present disclosure refers to the mutation of the 3rd amino acid of SEQ ID NO: 2 from the previous “P” to “T”, and “L8P” refers to the mutation of the 8th amino acid of SEQ ID NO:2 from the previous “L” to “P”, and so on.

[0052] As another embodiment, the immunoglobulin constant region provided by the present disclosure can be introduced with one or more amino acid modifications, such as substitution (i.e., mutation), addition (i.e., insertion) or deletion (i.e., absence).

[0053] The term “telitacicept” (or called as Tai′ai, which may be used interchangeably in the present disclosure) used in the present disclosure refers to a TACI-Fc fusion protein, having an INN name of Telitacicept and an amino acid sequence set forth in SEQ ID NO: 4, or referring to https://extranet.who.int/soinn/mod/page/view.php?id=137&inn_n=10932.

[0054] The TACI-Fc fusion protein of the present disclosure may be administered by any one of various routes, which include, but are not limited to oral administration, intravenous injection, intramuscular injection, intraarterial injection, intramedullary injection, intraperitoneal injection, intrathecal injection, intra-cardiac and-cerebral administration, transdermal administration, transdermal administration, topical administration, subcutaneous administration, intranasal administration, enteral administration, sublingual administration, vaginal administration, rectal administration, etc.

[0055] The term “membranous nephropathy” used in the present disclosure refers to a series of diseases sharing a common histo-pathological pattern, i.e., the presence of immunoglobulins and immune deposits containing complement in the subepithelial space.

[0056] The term “idiopathic membranous nephropathy” used in the present disclosure refers to an organ-specific autoimmune disease that occurs in the absence of any identified cause or initiating event, including, but not limited to, PLA₂R-associated idiopathic membranous nephropathy, THS7A-associated idiopathic membranous nephropathy, NELL-1-associated idiopathic membranous nephropathy, Sema3B-associated idiopathic membranous nephropathy, and other associated idiopathic membranous nephropathies.

[0057] The term “secondary membranous nephropathy” used in the present disclosure refers to a glomerular disease with clear systemic disorder involving nephropathy and pathological changes to membranous nephropathy. The cause of the secondary membranous nephropathy includes an immunological disease (e.g., systemic lupus erythematosus, type 1 diabetes mellitus, rheumatoid arthritis, Hashimoto's thyroiditis, Graves' disease, mixed connective tissue disease, allergic purpura, primary biliary cirrhosis, small bowel enteropathy syndrome, anti-glomerular basement membrane nephritis, ANCA-associated crescentic nephritis, graft-versus-host disease, bone marrow and stem cell transplantation, etc.), infection and parasitic diseases (e.g., HBV, HCV, syphilis, filariasis, cysticercosis, schistosome, plasmodium and leprosy), and drugs and toxins (e.g. gold preparation, penicillamine, non-steroidal anti-inflammatory drugs, mercury, captopril, formaldehyde, hydrocarbons) and others (e.g. tumors and kidney transplantation).

[0058] The term “PLA₂R-positive” used in the present disclosure means that PLA2R is detected in the blood of the patient, i.e., the patient is serologically positive for PLA2R.

[0059] The term “PLA2R-negative” used in the present disclosure means that PLA2R is not detected in the blood of the patient.

[0060] The term “conventional therapy of membranous nephropathy” used in the present disclosure exemplarily means that if the quantification of the 24-hour urine protein of the patient with membranous nephropathy is less than 3.5 g; or between 3.5g and 8g the renal function is normal and there is no high-risk phenomenon, pril drugs and sartan drugs are usually used to reduce urine protein, and supportive therapy, such as diuresis, antihypertensive and anticoagulant treatment is also given.

[0061] The term “combination therapy of hormone and immunosuppressant” used in the present disclosure exemplarily means that if the quantification of the 24-hour urine protein of the patient with membranous nephropathy is greater than 3.5 g accompanied by renal function decrease; or the urine protein is greater than 8 g, a combination therapy with hormone and immunosuppressant is adopted for treatment, wherein the immunosuppressant includes, but is not limited to tacrolimus and cyclosporine.

[0062] The term “monoclonal antibody drugs therapy” used in the present disclosure exemplarily refers to therapy using, but not limited to, rituximab, as recommended in the 2021 KDIGO Guideline, for example, twice administration of rituximab 1000 mg via vein within 2 weeks; rituximab 375 mg/m² body surface area weekly, total 1-4 times.

[0063] The term “cyclical administration of cyclophosphamide in combination with hormone drugs” used in the present disclosure refers to therapy as recommended in the 2021 KDIGO Guideline, intravenous injection of methylprednisolone 1 g for 3 consecutive days in the first few days of the 1^st, 3^rd, and 5^th month; oral prednisone 0.5 mg/kg/day; and oral cyclophosphamide 2.5 mg/kg body weight/day in the 2^nd, 4^th and 6^th month.

[0064] The term “continuous administration of cyclophosphamide in combination with hormone drugs” used in the present disclosure refers to therapy as recommended in the 2021 KDIGO Guideline, intravenous injection of methylprednisolone 1 g for 3 consecutive days in the first few days of the 1st, 3rd, and 5th month; oral prednisone 0.5 mg/kg every other day, for 1-6 months, then gradually tapered; and oral cyclophosphamide 1.5 mg/kg body weight/day for 16 months.

[0065] The embodiments of the present disclosure will be described in detail below in conjunction with examples. However, it is understood that the following examples are only intended to illustrate the present disclosure, and should not be construed as limiting the scope of the present disclosure.

[0066] This prospective, single-centre, unblinded, single-arm clinical trial primarily aimed to evaluate the efficacy and safety of telitacicept in the treatment of patients with membranous nephropathy, and to explore potential side effects of telitacicept in the treatment of patients with refractory membranous nephropathy. It was planned to enroll 30 patients with membranous nephropathy (12 patients had been enrolled for mid-term analysis) as subjects, receiving subcutaneous injection of 160 mg of telitacicept once a week for 48 weeks.

• • [0067] Patients diagnosed with primary membranous nephropathy by pathologically renal puncture and also positive for PLA2R antibodies;
  • [0068] Age 18-70 years;
  • [0069] Maintain 24-hour urine protein (UTP)≥3.5 g on the basis of adequate ACEI/ARB drug treatment for at least 3 months prior to enrollment;
  • [0070] Stable blood pressure, ≤140/90 mmHg;
  • [0071] Estimated glomerular filtration rate (eGFR)>45 mL/min/1.73m²;
  • [0072] Agree to maintain a stable diet and sodium intake during the study period;
  • [0073] Agree and sign the informed consent form.

[0074] Subjects were also excluded according to the following criteria:

• • [0075] Unstable urine protein quantification within the last 2 months, with a fluctuation of 24-hour urine protein quantification >2 g/d;
  • [0076] Combined with chronic liver disease or liver enzymes exceeding the upper limit of normal by more than 3 times;
  • [0077] New onset of cardiovascular or cerebrovascular disease (such as acute coronary syndrome, heart failure, cerebral infarction and brain stroke) within 3 months;
  • [0078] Uncontrolled severe hypertension;
  • [0079] Malignant tumor;
  • [0080] Patients with severe infections;
  • [0081] Patients who have previously used telitacicept, or are allergic to telitacicept or other contraindication;
  • [0082] Pregnancy or lactation;
  • [0083] Life expectancy less than 6 months;
  • [0084] Currently participating in other clinical studies;
  • [0085] Other situations as determined to be unsuitable for participation in this study by the investigator.

		Evaluation
Number	Indicator	time	Endpoint
1	Excretion level	Week 48	Complete remission: urine protein
	of 24-hour		content below 0.3 g/24 h
	urine protein at		Partial remission: urine protein
	week 48		content of 0.3-3.5 g/24 h, or 50%
			reduction in urine protein
			compared with baseline

Number	Indicators	Evaluation time
1	Changes in 24-hour urine protein content (or urine	Week 0, 4, 8, 12, 16, 20, 24, 36 and
	protein/creatinine ratio and urine albumin/creatinine ratio)	48
2	Change in estimated glomerular filtration rate (eGFR)	Week 0, 4, 8, 12, 16, 20, 24, 36 and
		48
3	Changes in serum albumin	Week 0, 4, 8, 12, 16, 20, 24, 36 and
		48
4	Changes in immunoglobulins IgA, IgG, and IgM	Week 0, 4, 8, 12, 16, 20, 24, 36 and
		48
5	Side effects of drug	/

[0086] The primary endpoint of this study is the excretion level of 24-hour urine protein at week 48. Wherein complete remission was indicated by a 24-hour urine protein content of less than 0.3 g/24 h, and partial remission was indicated by a 24-hour urine protein content between 0.3-3.5 g/24 h or a 50% reduction in urine protein compared with baseline. At week 48 or the end of treatment, there were 10 subjects with a reduction in urine protein compared with baseline, accounting for 83.3% of the current enrolled population. Among them, a total of 5 subjects had a 24-hour urine protein content between 0.3-3.5 g/24 h, and 3 subjects had a reduction of more than 50% compared with baseline (the reduction percent compared with baseline was 70.86%, 77.42% and 94.17%, respectively). As a result, 5 subjects achieved partial remission in this trial, accounting 42% of the total number of enrolled population. The 24-hour urine protein indicator of the subjects at baseline and at week 48 or the end of treatment, and the reduction percent compared with baseline are detailed in Table 2.

TABLE 2
24-hour urine protein content and reduction
percent compared with baseline
		24-hour urine protein
	24-hour urine	(at week 48 or end of	reduction percent
	protein (baseline)	treatment)	compared with
Subject	Unit: ml/min	Unit: ml/min	baseline
Subject 1	4.53	1.32	70.86%
Subject 2	10.23	2.31	77.42%
Subject 3	7.19	0.419	94.17%
Subject 4	4.44	2.97	/
Subject 5	3.72	3.02	/

[0087] In this study, the average urine protein/creatinine ratio (UPCR) and urine albumin creatinine ratio (UACR) of the subjects decreased compared with the baseline. The decrease had statistical significance compared with the baseline.

5.2.2 Analysis of Change in Estimated Glomerular Filtration Rate (eGFR)

[0088] In this study, 4 subjects showed an increase in the indicator of estimated glomerular filtration rate (eGFR) after the end of medication, and the subject with the highest increase in eGFR increase from 47.9 mL/min/1.73m² to 62.46 mL/min/1.73 m², with the increase percent of 30.4%.

[0089] In this study, the average albumin level showed a reduction during the treatment process. After the end of medication, the average serum albumin level of enrolled subjects decreased by 0.59 g/L compared with the baseline. The diachronic change value of albumin is shown in FIG. 1.

[0090] Compared with the baseline, after 48 weeks of medication, the change rate of average IgG level of enrolled subjects showed an overall downward trend. The average IgG level was decreased by 2.60 g/L (the decrease rate was 38.8%). The diachronic change rate of average IgG level of the enrolled subjects is shown in FIG. 2.

[0091] Compared with the baseline, the change rate of average IgM level of enrolled subjects also showed an overall downward trend. After 48 weeks of medication, the average IgM level was decreased by 0.708 g/L (the decrease rate was 70.1%). The diachronic change rate of average IgM level of the enrolled subjects is shown in FIG. 3.

[0092] Compared with the baseline, the change rate of average IgA level of the enrolled subjects also showed an overall downward trend. After 48 weeks of medication, the average IgA level was decreased by 0.717 g/L (the decrease rate was 39.7%). The diachronic change rate of average IgA level of the enrolled subjects is shown in FIG. 4.

[0093] In this study, the existing data showed that telitacicept exhibited consistently improved clinical efficacy in the treatment of patients with primary membranous nephropathy, and the average urine protein/creatinine ratio (UPCR) and urine albumin/creatinine ratio (UACR) of the subjects decreased compared with the baseline. The decrease had statistical significance compared with the baseline. After the administration of telitacicept, the average level of IgG, IgA and IgM of subjects were significantly reduced compared with the baseline.

[0094] In this study, the current results showed that once-weekly administration of 160 mg of telitacicept had a good safety for the treatment of patients with primary membranous nephropathy. The severity of adverse events/adverse reactions was mild (CTCAE grade 1), and no grades 2, 3, 4, and 5 adverse events/adverse reactions occurred. There were no adverse events/adverse reactions that resulted in the withdrawal of subjects from the study or death occurred, and no serious adverse reactions occurred. Two subjects experienced adverse events during the study period, one of whom had abdominal pain and vomiting, but the occurrence of this adverse event/adverse reaction was not considered to be related to telitacicept, and the other had symptoms of skin pruritus which was relieved without drug administration after 2-3 days.

[0095] Based on the above results and analysis, in this study, the current trial data showed that telitacicept exhibited good clinical efficacy and safety in the treatment of patients with membranous nephropathy.

[0096] The above description is only for some embodiments by way of example only and without limitation to the combination of features necessary for carrying the present disclosure into effect. The headings provided herein are not intended to limit the various embodiments of the present disclosure. Terms such as “including”, “comprising” and “containing” are not intended to be limiting. In addition, unless otherwise indicated, the singular form “a”, “an”, or “the” includes plural references, as well as “or” means “and/or”. Unless otherwise defined herein, all scientific terms used herein have the same meaning as commonly understood in the art.

[0097] All publications and patents mentioned in the present application are incorporated herein by reference. Without departing from the scope and spirit of the present disclosure, various modifications and variations of the described method and composition of the present disclosure will be apparent in the art. Although the present disclosure has been described by using specific embodiments, it should be understood that the claimed disclosure should not be unduly limited to these specific embodiments. In fact, many variations of the described modes for carrying out the disclosure are intended to be included within the scope of the appended claims.