Dose Escalation Study of Talquetamab in Participants With Relapsed or Refractory Multiple Myeloma

Inclusion Criteria: * Documented initial diagnosis of multiple myeloma according to International Myeloma Working Group (IMWG) diagnostic criteria * Part 1: Participants with measurable multiple myeloma who have progressed on, or could not tolerate, all available established therapies. Part 2: Participants with multiple myeloma measurable by central laboratory assessment who have progressed on, or could not tolerate, all available established therapies; Serum monoclonal paraprotein (M-protein) level greater than or equal to (\>=) 1.0 gram per deciliter (g/dL) or urine M-protein level \>=200 milligram per 24 hours (mg/24 h) or light chain multiple myeloma without measurable disease in the serum or the urine: serum immunoglobulin free light chain (FLC) \>= 10 mg/dL and abnormal serum immunoglobulin kappa lambda FLC ratio; If central laboratory assessments are not available, relevant local laboratory measurements must exceed the minimum required level by at least 25% * Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1 * 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 \[beta-hCG\]) or urine * Sign an informed consent form (ICF) indicating that he or she understands the purpose of and procedures required for the study, and is willing to and able participate in the study. Consent is to be obtai…