CD19 CAR T-Cell Therapy for Refractory Systemic Lupus Erythematosus

Inclusion Criteria: * Age 16 to 55 years, male or female * Diagnosis of systemic lupus erythematosus (SLE) according to the 2019 EULAR/ACR classification criteria with a total score ≥ 10 * SLEDAI-2K score ≥ 8 at screening (with at least 4 points derived from laboratory parameters; excluding points attributable to central nervous system involvement) * Positive antinuclear antibody (ANA ≥ 1:80) OR positive anti-dsDNA OR positive anti-Sm antibody at screening or documented in medical history Refractory systemic lupus erythematosus or refractory lupus nephritis defined as one of the following: Refractory SLE: \- Failure to achieve adequate response, partial response, or stable disease control after ≥ 6 months of standard-of-care therapy (documented compliance). Standard therapy includes corticosteroids plus hydroxychloroquine and at least two of the following: calcineurin inhibitors, cyclophosphamide, mycophenolate mofetil, azathioprine, or B-cell-targeted therapy (e.g., rituximab, belimumab). Refractory Lupus Nephritis: * Persistent active lupus nephritis after two induction regimens, including intravenous cyclophosphamide and mycophenolate mofetil administered for ≥ 6 months (with or without calcineurin inhibitors, rituximab, or belimumab), AND: * Histopathologic confirmation of Class III or Class IV lupus nephritis, with or without Class V (ISN/RPS 2003 classification); isolated Class V is excluded * Proteinuria \> 1 g/24 hours OR urine protein-to-creatinine ratio \> 1 mg/mg * Adequate organ function: * ALT ≤ 5 × upper limit of normal; total bilirubin ≤ 34 μmol/L (≤ 2.0 mg/dL) * Pulmonary function: FVC ≥ 60% predicted OR FEV1 ≥ 60% predicted * Cardiac function: LVEF ≥ 50%, no uncontrolled arrhythmia, no intracardiac thrombus, no heart failure * Adequate hematologic parameters: * Absolute neutrophil count ≥ 0.8 × 10⁹/L (without growth factor support) * Absolute lymphocyte count ≥ 0.3 × 10⁹/L * Platelet count ≥ 50 × 10⁹/L * Hemoglobin ≥ 80 g/L (≥ 8.0 g/dL) * Ability to provide written informed consent * Agreement to use effective contraception during the study period (for participants of reproductive potential) Exclusion Criteria: * History of significant neurologic disorders (e.g., traumatic brain injury, seizure disorder, hemorrhagic conditions, impaired consciousness) * Significant cardiovascular disease within 3 months prior to screening (e.g., uncontrolled hypertension, NYHA Class III-IV heart failure, severe arrhythmia, unstable angina, myocardial infarction) * Prior kidney transplantation * Severe asthma requiring long-term treatment or respiratory failure * Severe hemolytic anemia requiring transfusion at intervals ≤ 7 days * Active viral infections (e.g., hepatitis B or C, HIV, tuberculosis, malaria, syphilis, CMV, EBV) or other life-threatening infectious diseases * Active bacterial infection confirmed by clinical evaluation, imaging, or laboratory testing * Use of the following prior to leukapheresis: * Anti-CD20 therapy, cyclophosphamide, live or attenuated vaccines within 1 month * Systemic corticosteroids \> 10 mg/day (prednisone equivalent), T-cell-targeted therapy (e.g., mycophenolate mofetil, calcineurin inhibitors), immunosuppressive agents, or antimalarial agents within 7 days * Prior anti-CD19 therapy * Prior T-cell-based cellular therapy or gene therapy, including CAR-T therapy * Current or prior malignancy * Known hypersensitivity to study-related agents * Pregnant or breastfeeding women * Active antiphospholipid syndrome (stable antiphospholipid antibody positivity without active APS is permitted) * Participation in another clinical trial at the time of screening * Any condition that, in the investigator's judgment, would interfere with protocol compliance or study participation