A Study of Whether Ide-cel (bb2121) Can Be Made From People With Multiple Myeloma Who Have Had a Hematopoietic Cell Transplant

Eligible patients will undergo leukapheresis, receive lymphodepleting (LD) chemotherapy followed by infusion of Ide-Cel or Cilta-Cel, and be monitored daily for 14 days, three times a week until day + 30 after CAR T infusion and monthly until 12 months post CAR T infusion.