A Study of Talquetamab in Participants With Relapsed or Refractory Multiple Myeloma

Inclusion Criteria:

• Documented initial diagnosis of multiple myeloma according to international myelomaworking group (IMWG) diagnostic criteria

• Part 3: Measurable disease cohort A, cohort B, cohort C and cohort D: multiplemyeloma must be measurable by central laboratory assessment; Cohort E: Multiplemyeloma 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 andprior to the first dose of study drug using a highly sensitive pregnancy test eitherserum (beta human chorionic gonadotropin [hCG]) or urine

• Willing and able to adhere to the prohibitions and restrictions specified in thisprotocol

Exclusion Criteria:

• Part 3 only: Cohort A and Cohort C only: exposed to a CAR-T or T cell redirectiontherapy at any time. Cohort B, Cohort D and Cohort E: T cell redirection therapywithin 3 months

• Toxicities from previous anticancer therapies should have resolved to baselinelevels or to Grade 1 or less except for alopecia or peripheral neuropathy

• Received a cumulative dose of corticosteroids equivalent to >= 140 milligram (mg) ofprednisone within the 14-day period before the first dose of study drug (does notinclude pretreatment medication)

• Stroke or seizure within 6 months prior to signing the informed consent form (ICF)