Anti-BCMA CAR-T Cell Therapy for the R/R Multiple Myeloma

5×10\^7 /KG 15×10\^7 /KG 45×10\^7/KG Treatment follows a lymphodepletion, chemotherapy regimen that consists of Fludarabine (30 mg/m2 per day) and Cyclophosphamide (300mg/m2 per day) for 3 days prior to cell infusion.