CAR-based cellular therapy for refractory systemic lupus erythematosus: an overlap-controlled systematic review.

Objectives: To define the current evidence for CAR-based cellular therapy in relapsed or refractory systemic lupus erythematosus (SLE) by resolving overlapping reports and synthesising patient-level phenotype, safety and efficacy data. The primary purpose was evidence mapping with duplicate-count control; mechanistic immune-reset interpretation and platform differences were treated as secondary, hypothesis-generating questions rather than formal comparative-effectiveness analyses. Methods: PubMed, Embase and Web of Science were searched for reports published from January 2020 to March 2026. Eligible records described CAR-based cellular therapy in relapsed, refractory or organ-threatening SLE. Overlapping publication streams were collapsed into independent study units, and a deduplicated patient-level master dataset was constructed. Outcomes were summarised descriptively using conservative exact patient-level attribution, with endpoint evaluability reported separately from observed outcome proportions. Results: Twenty-one independent study units comprising 114 counted patients were included. The cohort was predominantly female (100/114, 87.7%), young (median age 32.0 years) and heavily pretreated, with renal involvement in 89 patients (78.1%). Autologous CD19 CAR-T and BCMA-containing platforms accounted for most treated patients, with additional allogeneic CAR-T and CAR-NK experience. Among exactly evaluable rows, clinical response was documented in 45 of 45 patients, DORIS remission in 13 of 15, SLE Responder Index-4 response in 20 of 20, renal improvement in five of five and drug-free remission in 28 of 58. These proportions should not be read as pooled response rates because exact endpoint denominators were small or incomplete for several outcomes. Cytokine release syndrome was usually low grade, and immune effector cell-associated neurotoxicity syndrome was uncommon. Severe inflammatory toxicities occurred in selected paediatric or highly inflammatory settings. Endpoint evaluability varied substantially across studies. Conclusion: CAR-based cellular therapy shows substantial promise as an immune-reset strategy for refractory SLE, particularly in renal-dominant disease. However, current evidence remains early, uncontrolled and incompletely reported. Sparse exactly evaluable denominators, publication bias, selective outcome reporting and short follow-up preclude definitive platform comparisons, supporting standardised prospective studies with harmonised efficacy, immune-reconstitution and toxicity endpoints. Systematic review registration: https://www.crd.york.ac.uk/prospero/, identifier CRD420261330006.