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

Inclusion Criteria: - * Documented diagnosis of multiple myeloma according to IMWG diagnostic criteria * Eastern Cooperative Oncology Group (ECOG) Performance Status score of 0 or 1 * Measurable disease: Cohort A and Cohort C: Multiple myeloma must be measurable by central laboratory assessment * A female participant of childbearing potential must have a negative pregnancy test at screening * Willing and able to adhere to the prohibitions and restrictions specified in this protocol * Cohort A: received at least \>=3 prior lines of therapy and previously received a PI, an IMiD and an anti-CD38 monoclonal antibody; Cohort C: received \>= 3 prior lines of therapy that included a PI, an IMiD, an anti-CD38 monoclonal antibody, and an anti-B cell maturation antigen (BCMA) treatment (with CART-T cells or an antibody drug conjugate (ADC) Exclusion Criteria: * Plasma cell leukemia, Waldenström's macroglobulinemia, POEMS syndrome, or primary amyloid light-chain amyloidosis * The following medical conditions: Pulmonary compromise requiring supplemental oxygen use to maintain adequate oxygenation, human immunodeficiency virus (HIV) infection, hepatitis B or C infection, stroke or seizure less than or equal to (\<=) 6 m, autoimmune disease, uncontrolled systemic infection, cardiac conditions (Myocardial Infarction \<= 6 m, stage III-IV congestive heart failure, etc) * Received any therapy that is targeted to BCMA, with the exception of Cohort C in Part 3 * Prior antitumor therapy, with…