Combination of Rituximab and Cyclosporine in the Treatment of Primary Membranous Nephropathy

High-grade proteinuria is one of the key determinants of adverse renal prognosis in patients with primary membranous nephropathy (PMN).The main purpose of this study is to determine whether Rituximab combined with Cyclosporine is superior to Rituximab monotherapy in inducing remission of proteinuria in patients with PMN.

Inclusion Criteria: 1. Age 18-80 years. 2. Primary membranous nephropathy confirmed by renal biopsy. 3. 24-hour urinary protein quantification \> 5.0 g/24h and serum albumin \< 30 g/L after at least 3 months of treatment with RAAS blockers. 4. eGFR ≥ 40 mL/min/1.73 m². 5. Well-controlled blood pressure (≤140/90 mmHg) in the recent 3 months. 6. Signed informed consent form. Exclusion Criteria: 1. Secondary causes of membranous nephropathy, such as that secondary to systemic lupus erythematosus, malignant tumors, hepatitis B virus infection, heavy metal poisoning; 2. Coexistence of other types of kidney diseases; 3. Use of rituximab within the past 12 months; 4. Use of corticosteroids, cyclophosphamide, cyclosporine, mycophenolate mofetil, or leflunomide within the past 3 months; 5. Active infection: active tuberculosis, HBsAg positivity or HBV-DNA indicating viral replication, positive HCV antibody, HIV infection; 6. New-onset cardiovascular or cerebrovascular diseases within the past 3 7. Severe liver disease: AST and ALT \> 3 times range upper limit ; 8. Uncontrolled severe hypertension; 9. Newly diagnosed or recurrent malignant tumors within the past 5 years; 10. Coexistent autoimmune diseases; 11. Pregnancy, lactation, or recent plans for pregnancy; 12. Life expectancy less than 12 months; 13. Participation in other clinical trials within the past 3 months; 14. Unwillingness to sign the informed consent form; 15. Any other condition deemed unsuitable for the study by the investigator.