The purpose of this study is to evaluate the efficacy and safety of talquetamab in participants with relapsed or refractory multiple myeloma at the recommended Phase 2 dose(s) (RP2Ds) (Part 3).
Documented initial diagnosis of multiple myeloma according to international myeloma working group (IMWG) diagnostic criteria
Part 3: Measurable disease cohort A, cohort B, cohort C and cohort D: multiple myeloma must be measurable by central laboratory assessment; Cohort E: Multiple myeloma must be measurable by local laboratory assessment
Eastern Cooperative Oncology Group (ECOG) performance status score of 0 to 2
Women of childbearing potential must have a negative pregnancy test at screening and prior to the first dose of study drug using a highly sensitive pregnancy test either serum (beta human chorionic gonadotropin [hCG]) or urine
Part 3 only: Cohort A and Cohort C only: exposed to a CAR-T or T cell redirection therapy at any time. Cohort B, Cohort D and Cohort E: T cell redirection therapy within 3 months
Toxicities from previous anticancer therapies should have resolved to baseline levels or to Grade 1 or less except for alopecia or peripheral neuropathy
Received a cumulative dose of corticosteroids equivalent to >= 140 milligram (mg) of prednisone within the 14-day period before the first dose of study drug (does not include pretreatment medication)
Stroke or seizure within 6 months prior to signing the informed consent form (ICF)