A Study of Telitacicept in Patients with Primary Immunoglobulin A（IgA） Nephropathy

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/daybased 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 useof ACEI/ARB medication at the maximum tolerated dose/maximum allowable dose within 4weeks prior to randomization. Subjects who use both ACEIs and ARBs will be excluded.

Exclusion Criteria:

1. Clinically significant abnormal laboratory tests;

2. Secondary IgA nephropathy;

3. Other types of glomerular disease such as crescentic glomerulonephritis（>50%）,minimal change nephropathy with IgA deposition;

4. Renal transplant;

5. Cirrhosis, as assessed by the investigator;

6. Experienced any of the following cardiovascular and cerebrovascular events within 24weeks prior to randomization: myocardial infarction, unstable angina, ventriculararrhythmia, New York Heart Association（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 duringthe screening period;

8. Poorly controlled type 1 and type 2 diabetes (glycated hemoglobin A1c[HbA1c]>8% or 64mmol/mol);

9. Received immunosuppressants within 12 weeks prior to randomization, including butnot limited to cyclophosphamide, azathioprine, mycophenolate, leflunomide,tacrolimus, cyclosporine, Tripterygium wilfordii;

10. Received anti-CD20 therapy (for example, Rituximab Injection) within 24 weeks priorto randomization;

11. Received systemic glucocorticoid treatment within 12 weeks prior to randomization,excluding the followings: ① received systemic treatment with prednisolone ≤ 0.5mg/kgor 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 nasalinhalation;

12. Hospitalization or intravenous anti-infective therapy for active infection within 4weeks prior to randomization;

13. Active tuberculosis and untreated latent tuberculosis;

14. Hepatitis B: patients with active hepatitis (patients with positive HBsAg) or latenthepatitis B (patients with positive HBcAb and positive HBV-DNA);

15. Hepatitis C;

16. Patients with HIV;

17. Malignancy within the past 5 years, except for treated cutaneous basal cellcarcinoma, cutaneous squamous cell carcinoma, colon polyps, or cervical cancer insitu;

18. Pregnant women, lactating women, and subjects with childbearing plans during thetrial;

19. Allergic to biological products of human origin;

20. Received any investigational therapy within 4 weeks or within 5 times the half-lifeof the investigational product (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. Not suitable for the study in the opinion of the investigator.