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

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.