A Study to Learn How Linvoseltamab (REGN5458) Will Work Compared to the Elotuzumab, Pomalidimide and Dexamethasone (EPd) Combination, in Participants With Relapsed/Refractory Multiple Myeloma

The primary objective of this study is to compare progression-free survival (PFS) per the Independent Review Committee (IRC) between participants treated with linvoseltamab monotherapy and EPd.The key secondary objectives are:To compare the anti-tumor activity per IRC between linvoseltamab monotherapy and EPd as measured byobjective response≥very good partial response (VGPR)≥ complete response (CR)To compare the incidence of minimal residual disease (MRD) negative status (10^-5) in the bone marrow between linvoseltamab monotherapy and EPdTo compare overall survival (OS) between linvoseltamab monotherapy and EPdTo evaluate the treatment effects on pain symptom between linvoseltamab monotherapy and EPdOther secondary objectives include:To evaluate the safety and tolerability of linvoseltamab monotherapy compared to EPdTo compare PFS per the investigator between participants treated with linvoseltamab monotherapy and EPd.To compare the anti-tumor activity per the investigator between linvoseltamab monotherapy and EPd as measured byObjective response≥VGPR≥CRTo evaluate duration of response (DOR) per investigator and IRC for participants achieving objective response on linvoseltamab monotherapy and on EPdTo evaluate the duration of MRD negative status in the bone marrow in participants receiving linvoseltamab monotherapy and EPdTo evaluate the time to response for participants with response ≥PR for linvoseltamab monotherapy and EPdTo evaluate the pharmacokinetics (PK) of linvoseltamabTo evaluate the immunogenicity of linvoseltamabTo evaluate the effects on patient reported quality of life (QoL), functioning and symptoms between linvoseltamab monotherapy and EPd

Key Inclusion Criteria:Eastern Cooperative Oncology Group (ECOG) performance status ≤1. Patients with ECOG 2 solely due to local symptoms of myeloma (e.g. pain) may be allowed after discussion with the Medical Monitor.Received at least 1 and no more than 4 prior lines of anti-neoplastic MM therapies, including lenalidomide and a proteasome inhibitor and demonstrated disease progression on or after the last therapy as defined by the 2016 IMWG criteria. Participants who have received only 1 line of prior line of antimyeloma therapy must be lenalidomide refractory, as described in the protocol.Patients must have measurable disease for response assessment as per the 2016 IMWG response assessment criteria, as described in the protocolAdequate hematologic, hepatic, renal and cardiac function, as well as evidence of adequate bone marrow reservesLife expectancy of at least 6 monthsKey Exclusion Criteria:Diagnosis of plasma cell leukemia, amyloidosis, Waldenström macroglobulinemia, or POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes)Prior treatment with elotuzumab and/or pomalidomideParticipants with known MM brain lesions or meningeal involvementTreatment with any systemic anti-cancer therapy within 5 half-lives or within 28 days before first administration of study drug, whichever is shorterHistory of allogeneic stem cell transplantation within 6 months, or autologous stem cell transplantation within 12 weeks of the start of study treatmentPrior treatment with B-cell maturation antigen (BCMA) directed immunotherapiesAny infection requiring hospitalization or treatment with IV anti-infectives within 2 weeks of first administration of study drugUncontrolled infection with human immunodeficiency virus (HIV), hepatitis B or hepatitis C; or another uncontrolled infection, as defined in the protocol.NOTE: Other protocol defined inclusion/exclusion criteria apply