A Study Comparing JNJ-79635322 and an Anti-B-cell Maturation Antigen (BCMA)xCD3 Bispecific Antibody in Participants With Relapsed or Refractory Multiple Myeloma

The purpose of this study is to evaluate how well JNJ-79635322 works when compared with an anti-B-cell maturation antigen (BCMA)xCD3 bispecific antibody.

Inclusion: * Documented diagnosis of multiple myeloma (MM) as defined by the criteria below: 1. MM diagnosis according to the international myeloma working group (IMWG) diagnostic criteria 2. Measurable disease at screening as assessed by central laboratory * Received at least 3 prior lines of antimyeloma therapy including a proteasome inhibitor (PI), an immunomodulatory drug (IMiD), and an anti-cluster of differentiation (CD)38 antibody * Documented evidence of progressive disease (PD) or failure to achieve a response (that is partial response \[PR\] or better) to the last line of therapy based on investigator's determination of response by IMWG criteria * Have discontinued concurrent use of any other anticancer treatment (including nonpalliative radiotherapy) or investigational agent * Have an eastern cooperative oncology group (ECOG) performance status of 0 to 2 at screening and immediately before the start of study treatment administration Exclusion: * Active hepatitis of infectious origin * Known active or prior central nervous system (CNS) involvement or exhibits clinical signs of meningeal involvement of MM * Suspected or known allergies, hypersensitivity, or intolerance to the excipients of JNJ-79635322 and Teclistamab * Major surgery , (example, requiring general anesthesia) within 2 weeks before first dose, or will not have fully recovered from surgery, or has surgery planned during the time the participant is expected to participate in the study * Received or plans to receive any live, attenuated vaccine within 4 weeks before the first dose of study treatment, during, or within 90 days after the last dose of study treatment