Participants with relapsed/refractory multiple myeloma can participate if all eligibility criteria are met. Tests required to determine eligibility include disease assessments, a physical exam, Electrocardiograph, Computedtomography （CT）/Magnetic Resonance Imaging(MRI)/Positron Emission Tomography（PET）, and blood draws. Participants receive chemotherapy prior to the infusion of BCMA CAR+ T cells. After the infusion, participants will be followed for side effects and effect of BCMA CAR+ T cells. Study procedures may be performed while hospitalized.
A Phase Ⅱ Clinical Study Evaluating the Efficacy and Safety of Human BCMA Targeted T Cells Injection（BCMA CAR-T） Therapy for R/R MM.~Patients will be given a conditioning chemotherapy regimen of fludarabine and cyclophosphamide followed by a single infusion of BCMA CAR+ T cells.