Safety and Efficacy of CD19 Chimeric Antigen Receptor T-Cell (CAR-T) in the Treatment of Refractory Membranous Nephropathy

Inclusion criteria

• Confirmed as primary membranous nephropathy (PMN) by renal biopsy.
• Classified as moderate-risk or high-risk refractory membranous nephropathy (rMN).
• Moderate-risk rMN is defined as: eGFR ≥ 90 ml/min/1.73m² AND 24-hour urinary protein > 3.5g/d, with a reduction of no more than 50% within 6 months of receiving renin-angiotensin system inhibitor (RASi) therapy.
• High-risk rMN is defined as meeting one of the following:

• eGFR < 60 ml/min/1.73m² and/or persistent proteinuria > 8g/d for more than 6 months.
• Normal eGFR with proteinuria > 3.5g/d and ≤50% reduction after 6 months of RASi therapy, PLUS at least one of the following: Serum albumin < 25g/L; PLA2R antibody > 50 RU/mL; Urinary α1-microglobulin > 40 μg/min; Urinary IgG > 1 μg/min; Urinary β2-microglobulin > 250 mg/d; IgG/albumin clearance ratio > 0.20.
• Diagnosis of rMN requires failure of adequate first-line immunosuppressive therapy (≥6 months of steroids+cyclophosphamide, CNI, or rituximab), defined by any of the following: persistent high-titer anti-PLA2R antibody; for antibody-negative patients, persistent nephrotic syndrome (protein >3.5g/d, albumin <30g/L); <50% reduction in proteinuria.
• Age ≥ 18 years.
• Adequate organ function, defined as:

• Renal: eGFR ≥ 30 ml/min/1.73m².
• Hepatic: ALT and AST ≤ 2.5 x ULN; Total bilirubin ≤ 1.5 x ULN.
• Cardiac: LVEF ≥ 50%; NYHA Class I or II; No significant arrhythmias requiring intervention; No major cardiovascular events within the past 6 months.
• Respiratory: SpO2 > 92% on room air.
• Ability to understand and willingness to sign an Informed Consent Form.

Exclusion criteria

• Secondary membranous nephropathy (e.g., due to SLE, malignancy, drugs, infection).
• Active infection requiring IV antibiotics, active tuberculosis, or positive viral serology indicating active infection, including:

• HBV: HBsAg (+) and/or HBcAb (+) with detectable HBV DNA.
• HCV: HCV Ab (+) with detectable HCV RNA.
• HIV Ab (+).
• Active EBV or CMV infection (IgM+ or DNA above normal).
• Positive syphilis (Treponema pallidum) antibody (requires evaluation for active infection).
• Severe uncontrolled comorbidities, including:

• Uncontrolled hypertension (persistent SBP > 160 mmHg or DBP > 100 mmHg).
• Uncontrolled diabetes (HbA1c > 8% or random glucose ≥11.1 mmol/L) or diabetic nephropathy.
• Symptomatic deep vein thrombosis or pulmonary embolism within the past 6 months.
• Active peptic ulcer or gastrointestinal bleeding within the past 6 months.
• Severe congenital or acquired immunodeficiency.
• Severe CNS diseases (e.g., catastrophic APS, uncontrolled epilepsy).
• End-stage organ failure not attributable to PMN.
• History of malignancy within the past 5 years, except for adequately treated non-melanoma skin cancer, cervical carcinoma in situ, or thyroid cancer.
• Specific treatment history or plans, including:

• Prior receipt of any cell therapy (e.g., MSCs, HSCT).
• Major surgery within 24 weeks before or planned within 24 weeks after enrollment.
• Planned kidney transplantation within 3 years.
• History of substance abuse.
• Participation in another interventional clinical trial within 3 months prior to enrollment.
• Pregnant or lactating women.
• Inability to understand the study or provide informed consent (e.g., severe dementia, mental illness).
• Any other condition deemed by the investigator to increase risk, interfere with assessment, or affect compliance.