Cevostamab Following CAR T Cell Therapy for RRMM

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. Subjects receive a single step-up dose of 3.6 mg of cevostamab on cycle 1, day 1 (C1D1), followed by the recommended target dose (160 mg, 132mg, or 90 mg based on results of safety run-in data and safety review) on C1D8. Myeloma responses are assessed every cycle, and a repeat bone marrow aspirate and biopsy (BMbx) is performed at the start of cycle 8. If participants are not in an MRD-negative CR at this timepoint (or if the BM bx is inevaluable/indeterminate for CR or MRD testing), they continue with another 8 cycles (C9-16) of cevostamab. If they are in MRD-negative CR at start of C8, they stop therapy after receiving this cycle and are observed.