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 264 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.

Treatment Sites in Georgia