Inclusion Criteria:

* Documented diagnosis of multiple myeloma according to International Myeloma Working Group (IMWG) diagnostic criteria

* Measurable multiple myeloma that is relapsed or refractory to established therapies with known clinical benefit in relapsed/refractory multiple myeloma or be intolerant of those established multiple myeloma therapies, and a candidate for Teclistamab treatment in the opinion of the treating physician. Prior lines of therapy must include a proteasome inhibitor, an immunomodulatory drug and anti-CD38 monoclonal antibody in any order during the course of treatment. Participants who could not tolerate a proteasome inhibitor or immunomodulatory drugs and an anti-CD38 monoclonal antibody are allowed

* Eastern Cooperative Oncology Group (ECOG) Performance Status score of 0 or 1

* Female participants of childbearing potential must use acceptable method of contraception

* Participants must sign an ICF indicating that he or she understands the purpose of and procedures required for the study and is willing to participate in the study. Consent is to be obtained prior to the initiation of any study-related tests or procedures that are not part of standard-of-care for the participant's disease

Exclusion Criteria:

* Prior treatment with any B cell maturation antigen (BCMA) targeted therapy

* Prior antitumor therapy as follows, before the first dose of study drug: Targeted therapy, epigenetic therapy, or treatment with an investigational drug or used an invasive investigational medical device within 21 days or at least 5 half-lives, whichever is less; Monoclonal antibody treatment for multiple myeloma within 21 days; Cytotoxic therapy within 21 days; Proteasome inhibitor therapy within 14 days; Immunomodulatory agent therapy within 7 days; Gene modified adoptive cell therapy (example, chimeric antigen receptor modified T cells, natural killer [NK] cells) within 3 months; Radiotherapy within 14 days or focal radiation within 7 days

* Toxicities from previous anticancer therapies that have not resolved to baseline levels or to Grade 1 or less except for alopecia or peripheral neuropathy

* Received a cumulative dose of corticosteroids equivalent to >= 140 milligram (mg) of prednisone within the 14-day period before the first dose of study drug (does not include pretreatment medication)

* Known active central nervous system (CNS) involvement or exhibits clinical signs of meningeal involvement of multiple myeloma