A Study Comparing Teclistamab Monotherapy Versus Pomalidomide, Bortezomib, Dexamethasone (PVd) or Carfilzomib, Dexamethasone (Kd) in Participants With Relapsed or Refractory Multiple Myeloma

The purpose of this study is to compare the efficacy of teclistamab with PVd/Kd in Part 1 and to further characterize safety and efficacy of an alternative dosing for teclistamab in Part 2 in participants with relapsed or refractory multiple myeloma.

Inclusion Criteria: * Documented diagnosis of multiple myeloma as defined by the criteria below: (a)Multiple myeloma diagnosis according to International Myeloma Working Group (IMWG) diagnostic criteria (b) Measurable disease at screening as defined by any of the following: (1) Serum M-protein level greater than or equal to (\>=)0.5 grams per deciliter (g/dL) (central laboratory); or (2) Urine M-protein level \>=200 milligrams (mg)/24 hours (central laboratory); or (3) Serum immunoglobulin free light chain \>=10 milligrams per deciliter (mg/dL) (central laboratory) and abnormal serum immunoglobulin kappa lambda free light chain ratio * Received 1 to 3 prior lines of antimyeloma therapy including a minimum of 2 consecutive cycles of an anti- cluster of differentiation 38 (CD38) monoclonal antibody at the approved dosing regimen in any prior line and 2 consecutive cycles of lenalidomide in any prior line * Documented evidence of progressive disease or failure to achieve a response to last line of therapy based on investigator's determination of response by International myeloma working group (IMWG) criteria * Have an Eastern Cooperative Oncology Group (ECOG) performance status score of 0 to 2 * A female participant must agree not to be pregnant, breast-feeding, or plan to become pregnant while enrolled in this study or within 6 months after the last dose of study treatment * Must be willing and able to adhere to the lifestyle restrictions specified in this protocol Exclusion Criteria: * Received any prior B cell maturation antigen (BCMA)-directed therapy * A participant is not eligible to receive PVd as control therapy if any of the following are present: (1) Received prior pomalidomide therapy, (2) Does not meet criteria for bortezomib retreatment (3) Contraindications or life-threatening allergies, hypersensitivity, or intolerance to pomalidomide or bortezomib, (4) Grade 1 peripheral neuropathy with pain or Grade greater than or equal to (\>=) 2 peripheral neuropathy as defined by National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) Version 5.0, (5) Received a strong cytochrome P (CYP) 3A4 inducer within 5 half-lives prior to randomization; A participant is not eligible to receive Kd as control therapy if any of the following are present:(1) Received prior carfilzomib therapy, (2) Uncontrolled hypertension, defined as an average systolic blood pressure greater than (\>)159 millimeters of mercury (mmHg) or diastolic blood pressure \>99 mmHg despite optimal treatment (3) Grade 2 peripheral neuropathy with pain or Grade \>=3 peripheral neuropathy as defined by NCI-CTCAE Version 5.0, (4) Contraindications or life-threatening allergies, hypersensitivity, or intolerance to carfilzomib (intolerance defined as prior therapy discontinued due to any adverse event \[AE\] related to carfilzomib) * Received a maximum cumulative dose of corticosteroids of \>=140 mg of prednisone or equivalent within 14 days prior to randomization * Received a live, attenuated vaccine within 4 weeks before randomization * Central nervous system (CNS) involvement or clinical signs of meningeal involvement of multiple myeloma * Plasma cell leukemia at the time of screening, Waldenstrom's macroglobulinemia, polyneuropathy, organomegaly, endocrinopathy, M-protein (POEMS) syndrome and skin changes, or primary amyloid light chain amyloidosis