A Study to Assess the Safety and Anti-Tumor Activity of REGN7945 in Combination With Linvoseltamab in Adult Participants With Relapsed/Refractory Multiple Myeloma

Key Inclusion Criteria:

• Eastern Cooperative Oncology Group (ECOG) performance status ≤1 as described in the protocol
• Received at least 3 lines of therapy including exposure to at least 1 anti-CD38 antibody, 1 immunomodulatory imide drug (IMiD), and 1 proteasome inhibitor (PI) and have demonstrated disease progression on or after the last therapy, as defined in the protocol. Prior treatment with other BCMA directed immunotherapies, including BCMA CAR-T cells and BCMA antibody-drug conjugates (Phase 1 and 2), and with BCMA x CD3 bispecific antibodies (Phase 1 only), is allowed
• Participants must have the measurable disease for response assessment as described in the protocol
• Adequate hematologic, hepatic, and renal function as described in the protocol

Key Exclusion Criteria:

• Diagnosis of plasma cell leukemia, primary systemic light-chain amyloidosis (including myeloma associated amyloidosis), Waldenström macroglobulinemia (lymphoplasmacytic lymphoma), or POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes)
• Treatment with any systemic anti-cancer therapy within 5 half-lives or within 28 days before first administration of study drug, whichever is shorter
• History of allogeneic stem cell transplantation within 6 months, or autologous stem cell transplantation within 12 weeks of the start of study treatment
• Treatment with systemic corticosteroid treatment with more than 10 mg per day of prednisone or steroid equivalent within 72 hours of start of study drug
• Participants who have known central nervous system (CNS) involvement with MM or known or suspected progressive multifocal leukoencephalopathy (PML), history of a neurocognitive condition or CNS disorder, or history of seizure within 12 months prior to study enrollment
• Live or live attenuated vaccination within 28 days before first study drug administration with a vector that has replicative potential
• Has received a COVID-19 vaccination within 1 week of planned start of study medication as described in the protocol
• Myelodysplastic syndrome or another malignancy in the past 3 years, except for nonmelanoma skin cancer, in situ carcinoma, thyroid cancer, or low-risk early stage prostate adenocarcinoma, as described in the protocol
• Significant cardiovascular disease as described in the protocol
• Uncontrolled infection with HIV, Hep B or Hep C infection, or other uncontrolled infection, such as CMV, as described in the protocol
• Known hypersensitivity to both allopurinol and rasburicase

Note: Other protocol-defined Inclusion/ Exclusion Criteria apply