This is a Phase 2, open-label, single-arm, single stage, single-institution study, with an
initial safety run-in period. Potential subjects 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 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 on day
+56 (+/- 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.