A Phase I/II Open-label, Single-arm, Multicenter Clinical Study to Evaluate the Safety and Efficacy of FKC289 in Subjects With Relapsed/Refractory Membranous Nephropathy

This Phase I study is designed to evaluate the safety and efficacy of FKC289 in subjects with relapsed/refractory Primary Membranous Nephropathy.The primary objectives are to assess the safety of FKC289 and to establish the recommended Phase II dose (RP2D).And this Phase II study is designed to evaluate the efficacy of FKC289.The primary objectives are to assess proportion of subjects achieving clinical response (including complete or partial response) at 6 months.

Inclusion Criteria: 1. Voluntarily signed the informed consent form (ICF); 2. Aged between 18-70 years old (inclusive); 3. Histologically confirmed diagnosis of primary membranous nephropathy by renal biopsy obtained within the past 2 years.; 4. Relapsed or refractory disease; 5. Anti-PLA2R antibody \> 50 RU/mL; 6. 24-hour urine protein \> 3.5 g at screening; 7. No active systemic infection (e.g., infectious pneumonia, pulmonary tuberculosis) within 2 weeks prior to leukapheresis; 8. Adequate bone marrow and major organ function (including hepatic, renal, cardiac, and pulmonary); Exclusion Criteria: 1. Secondary membranous nephropathy or patients with a prior diagnosis of other renal diseases; 2. Presence of any clinically significant cardiovascular disease within 6 months prior to screening; 3. Clinically significant central nervous system (CNS) disease or pathological abnormality; 4. History of solid organ transplantation (e.g., heart, lung, kidney, liver); 5. Presence of complete intestinal obstruction; 6. Moderate to severe pleural effusion or ascites that is difficult to control with conventional treatment and requires continuous catheter drainage;