A Study of Telitacicept for IgA Nephropathy (TELIGAN)

Inclusion Criteria: 1. Voluntary informed consent provided; 2. Male or female aged ≥ 18 years old; 3. IgA nephropathy confirmed by pathological biopsy; 4. During the screening period, UPCR ≥ 0.8 g/g or 24-hour urine protein ≥ 1.0 g/day based on 24-hour urine collection at Visit 1 and/or Visit 2 and at Visit 3; 5. eGFR ≥ 30 mL/min per 1.73 m\^2 (using the CKD-EPI); 6. Have been on a treatment regimen including ACEI/ARB for 12 weeks and on a stable use of ACEI/ARB medication at the maximum tolerated dose/maximum allowable dose within 4 weeks prior to randomization. Subjects who use both ACEIs and ARBs will be excluded. Exclusion Criteria: 1. Subjects with abnormal laboratory tests, including but not limited to the following: 1. White blood cell count \< 1.5×109/L 2. Neutrophils \< 1.0×109/L 3. Hemoglobin \< 85.0 g/L 4. Platelet count \< 80.0×109/L 5. Total bilirubin \>2×ULN 6. ALT\>3×ULN 7. AST\>3×ULN 8. Alkaline phosphatase\>2×ULN 9. Creatine kinase\>5×ULN 10. IgA\<10 mg/dL; or IgG≤400mg/dL； 2. Patients with secondary IgA nephropathy, including but not limited to: Henoch-Schonlein purpura, ankylosing spondylitis, systemic lupus erythematosus, etc.; 3. Patients with other types of glomerular disease such as crescentic glomerulonephritis, minimal change nephropathy with IgA deposition;; 4. Renal transplant; 5. Patients with cirrhosis, as assessed by the investigator; 6. Patients who experienced any of the following cardiovascular and cerebrovascular events within 24 weeks prior to randomization: myocardial infarction, unstable angina, ventricular arrhythmia, NYHA Class II or higher heart failure, stroke, etc.; 7. Sitting position SBP\>140 mmHg or DBP\>90 mmHg for at least once at 2 visits during the screening period; 8. Patients with poorly controlled type 1 and type 2 diabetes (glycated hemoglobin A1c\[HbA1c\] \> 8% or 64mmol/mol); 9. Treatment with immunosuppressants within 12 weeks prior to randomization, including but not limited to cyclophosphamide, azathioprine, mycophenolate, leflunomide, tacrolimus, cyclosporine, Tripterygium wilfordii; 10. Treatment with anti-CD20 therapy (for example, Rituximb Injection) within 24 weeks prior to randomization; 11. Received systemic glucocorticoid treatment within 12 weeks prior to randomization, excluding the followings: ① received systemic treatment with prednisolone ≤ 0.5mg/kg or equivalent glucocorticoid for non- IgA nephropathy for no more than 3 courses (≤ 2 weeks per course) in the past 52 weeks; ② topical administration or nasal inhalation; 12. Had hospitalization or intravenous anti-infective therapy for active infection within 4 weeks prior to randomization; 13. Patients with active tuberculosis; 14. Hepatitis B: patients with active or latent hepatitis B (potive HBcAb and HBV-DNA); According to the test results of hepatitis B five items, subjects with positive HBsAg will be excluded; subjects who are HBsAg-negative but HBcAb-positive, whether HBsAb is positive or negative, should be tested for HBV-DNA: if HBV-DNA is positive, patients should be excluded; if HBV-DNA is negative, patients can participate in the trial, and subjects are advised to take oral entecavir for prophylactic antiviral therapy during the trial; 15. Patients with hepatitis C; 16. Patients with HIV infection; 17. Patients with malignancy within the past 5 years, except for treated cutaneous basal cell carcinoma, cutaneous squamous cell carcinoma, colon polyps, or cervical cancer in situ; 18. Pregnant women, lactating women, and subjects with childbearing plans during the trial; 19. Allergic to biological products of human origin; 20. Participated in any clinical trial within 4 weeks or within 5 times the half-life of the investigational drug participating (whichever is longer) prior to randomization; 21. Received live vaccination within 4 weeks prior to randomization; 22. Drug or alcohol abuse/dependence within 52 weeks prior to randomization; 23. Other circumstances that, in the opinion of the investigator, are not suitable for participation in this study.