BCMA/GPRC5D Dual-Target CAR-T Cell Immunotherapy for Relapsed/Refractory Multiple Myeloma - NCT07927842

This is a single-center, open-label, single-arm, investigator-initiated clinical study to evaluate the safety, tolerability, and preliminary efficacy of SL4903, a BCMA/GPRC5D dual-target autologous CAR-T cell injection, in patients with relapsed or refractory multiple myeloma (R/R MM) whose clonal plasma cells are positive for BCMA and/or GPRC5D. After leukapheresis, participants receive lymphodepleting conditioning (fludarabine 30 mg/m\^2/day plus cyclophosphamide 500 mg/m\^2/day on Days -5 to -3), followed by a single intravenous infusion of SL4903 at a dose of 1×10\^6 CAR-positive cells/kg; bridging therapy (e.g., immunomodulatory drugs or anti-CD38 monoclonal antibody) is permitted between leukapheresis and conditioning at the investigator's discretion. Treatment-emergent adverse events, including cytokine release syndrome (CRS), neurotoxicity, hematologic toxicity, and organ toxicity, will be assessed within 3 months after infusion. Preliminary antitumor activity will be evaluated according to the 2016 International Myeloma Working Group (IMWG) criteria, including objective response rate (ORR), complete response rate (CRR), time to response (TTR), duration of response (DOR), progression-free survival (PFS), overall survival (OS), and measurable residual disease (MRD) negativity rate. Pharmacokinetics (Cmax, Tmax, persistence, and AUCd0-28 of CAR-T cells in peripheral blood by flow cytometry and qPCR) and pharmacodynamics (peripheral blood plasma cell proportion and cytokine levels) will also be evaluated. Participants will be followed for safety and efficacy for up to 2 years after cell therapy.