An Efficacy and Safety Study of bb2121 in Subjects With Relapsed and Refractory Multiple Myeloma and in Subjects With High-Risk Multiple Myeloma

This study is a multi-cohort, open-label, multicenter Phase 2 study to evaluate the efficacy and safety of bb2121 in participants with relapsed and refractory multiple myeloma (RRMM) (Cohort 1), in participants with RRMM who receive bridging therapy with talquetamab (Cohort 1b), in participants with multiple myeloma (MM) having progressed within 18 months of initial treatment with autologous stem cell transplantation (ASCT) (Cohort 2a) and without ASCT (Cohort 2b) or, in participants with inadequate response post ASCT during initial treatment (Cohort 2c) and the efficacy and safety of bb2121 used in combination with lenalidomide maintenance in participants with suboptimal response post ASCT (Cohort 3). Approximately 248 participants will be enrolled into one of three cohorts. Cohort 1 (including cohort 1b) will enroll approximately 126 RRMM subjects with ≥ 3 prior anti-myeloma treatment regimens. Cohort 2a will enroll approximately 39 MM subjects, with 1 prior anti-myeloma therapy including ASCT and with early relapse. Cohort 2b will enroll approximately 39 MM subjects with 1 prior anti-myeloma therapy not including ASCT and with early relapse. Cohort 2c will enroll approximately 30 MM subjects with inadequate response to ASCT during their initial anti-myeloma therapy. The cohorts will start in parallel and independently. Cohort 3 will enroll approximately 30 newly diagnosed multiple myeloma (NDMM) participants with suboptimal response to ASCT.

Anti-myeloma bridging treatment is allowed for disease control while bb2121 is being manufactured for cohorts 1, 2a and 2b only. In Cohort 1b only, subjects will receive bridging therapy with 1 to 2 cycles of talquetamab, and initiate Lymphodepleting (LD) chemotherapy at least 14 days after the last dose of talquetamab.