Dual-target BCMA-CD19 CAR-T Cell Therapy for RR/MM With Extramedullary Infiltration

This is a multicenter, open-label, non-randomized, single-arm clinical trial. Patients with relapsed/refractory multiple myeloma accompanied by extramedullary infiltration will receive BCMA - CD19 CAR-T cell therapy. The primary objective is to prospectively evaluate the safety of dual-targeting BCMA and CD19 CAR - T cell therapy for extramedullary infiltration in relapsed/refractory multiple myeloma. The primary endpoints are to assess the type and incidence of dose-limiting toxicity (DLT) within one month after the infusion of BCMA-CD19 CAR-T cells in patients, as well as the incidence and severity of adverse events within one month after the infusion. It is expected that no more than 18 participants will be recruited.