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:

1. Eastern Cooperative Oncology Group (ECOG) performance status ≤1 as described in theprotocol

2. Received at least 3 lines of therapy including exposure to at least 1 anti-CD38antibody, 1 immunomodulatory imide drug (IMiD), and 1 proteasome inhibitor (PI) andhave demonstrated disease progression on or after the last therapy, as defined inthe protocol. Prior treatment with other BCMA directed immunotherapies, includingBCMA CAR-T cells and BCMA antibody-drug conjugates (Phase 1 and 2), and with BCMA xCD3 bispecific antibodies (Phase 1 only), is allowed

3. Participants must have the measurable disease for response assessment as describedin the protocol

4. Adequate hematologic, hepatic, and renal function as described in the protocol

Key Exclusion Criteria:

1. 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)

2. Treatment with any systemic anti-cancer therapy within 5 half-lives or within 28days before first administration of study drug, whichever is shorter

3. History of allogeneic stem cell transplantation within 6 months, or autologous stemcell transplantation within 12 weeks of the start of study treatment

4. Treatment with systemic corticosteroid treatment with more than 10 mg per day ofprednisone or steroid equivalent within 72 hours of start of study drug

5. Participants who have known central nervous system (CNS) involvement with MM orknown or suspected progressive multifocal leukoencephalopathy (PML), history of aneurocognitive condition or CNS disorder, or history of seizure within 12 monthsprior to study enrollment

6. Live or live attenuated vaccination within 28 days before first study drugadministration with a vector that has replicative potential

7. Has received a COVID-19 vaccination within 1 week of planned start of studymedication as described in the protocol

8. Myelodysplastic syndrome or another malignancy in the past 3 years, except fornonmelanoma skin cancer, in situ carcinoma, thyroid cancer, or low-risk early stageprostate adenocarcinoma, as described in the protocol

9. Significant cardiovascular disease as described in the protocol

10. Uncontrolled infection with HIV, Hep B or Hep C infection, or other uncontrolledinfection, such as CMV, as described in the protocol

11. Known hypersensitivity to both allopurinol and rasburicase

Note: Other protocol-defined Inclusion/ Exclusion Criteria apply