Cevostamab Following CAR T Cell Therapy for RRMM

This is a Phase 2, open-label, single-arm, single stage, single-institution study, with an initial safety run-in period. Potential participants with relapsed/refractory myeloma who are undergoing standard of care, commercially-available BCMA-directed CAR T cell therapy may be identified pre-CAR T cell infusion but are not consented and enrolled until at least 4-6 weeks after CAR T cell infusion, once recovered from acute toxicities. Note: the lymphodepleting chemotherapy and CAR T cell therapy is being administered as part of standard clinical practice and is not considered part of this protocol. Alternative lymphodepleting regimens other than fludarabine and cyclophosphamide (eg in the setting of fludarabine shortages) are acceptable. Cevostamab will be given as an IV infusion once every 3 weeks, starting roughly 10 weeks (day 70 +/- 4 days) post-CAR T cell infusion, with subjects planned to receive 8 cycles initially. Aiming to assess the impact of cevostamab consolidation post-BCMA CAR T cell therapy on rate of MRD-negative complete remission (CR) at 12 months.