Key Inclusion Criteria:

• Eastern Cooperative Oncology Group (ECOG) performance status ≤1
• Relapsed/refractory multiple myeloma (MM): Progression of disease following at least 3 lines of therapy, or least 2 lines of therapy and either:
  • prior exposure to at least 1 anti-CD38 antibody, 1 IMiD and 1 PI or
  • double-refractory to 1 PI and 1 IMiD, or the combination of 1 PI and 1 IMiD. Cohort 1: Prior treatment with daratumumab is allowed if previously tolerated. However, patients cannot be refractory to an anti-CD38 antibody-containing regimen. In addition, patients must have a 6-month washout from prior anti-CD38 antibody therapy.
• Cohort 2: Prior treatment with carfilzomib is allowed if previously tolerated at the approved full dose. However, patients cannot be refractory to a carfilzomib-containing regimen. In addition, patients must have a 6-month washout from prior carfilzomib therapy.
• Cohort 3: Prior treatment with lenalidomide is allowed if previously tolerated at the approved full dose. However, a patient cannot be refractory to any combination regimen that included 25 mg of lenalidomide. In addition, patients must have a 6-month washout from prior lenalidomide therapy (including maintenance therapy).
• Cohort 4: Prior treatment with bortezomib is allowed if previously tolerated at the approved full dose. However, a patient cannot be refractory to any combination regimen including the approved induction dose of bortezomib. In addition, patients must have a 6-month washout from prior bortezomib therapy.
• Participants must have measurable disease and as defined in the protocol for response assessment as per the 2016 International Myeloma Working Group (IMWG) response assessment criteria
• Adequate creatinine clearance, hematologic and hepatic functions, as defined in protocol
• Life expectancy of at least 6 months

Key Exclusion Criteria:

• Diagnosis of plasma cell leukemia, primary light-chain amyloidosis (excluding myeloma associated amyloidosis), Waldenström macroglobulinemia (lymphoplasmacytic lymphoma), or POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes)
• Participants with known MM brain lesions or meningeal involvement
• Treatment with any systemic anti-myeloma therapy within 5 half-lives or within 21 days prior to first administration of study drug regimen, whichever is shorter.
• History of allogeneic stem cell transplantation, or autologous stem cell transplantation within 12 weeks of the start of study drug regimen
• For participants with peripheral neuropathy grade ≥2 receiving bortezomib-based treatment (cohort 4 only)
• Prior treatment with BCMA-directed immunotherapies, including any chimeric antigen receptor T cell (CAR T) therapy (Note: BCMA antibody-drug conjugates are not excluded)
• History of neurodegenerative condition or central nervous system (CNS) movement disorder or participants with a history of seizure within 12 months prior to study enrollment are excluded
• Live or attenuated vaccination within 28 days prior to first study drug regimen administration with a vector that has replicative potential
• Cardiac ejection fraction <40% by echocardiogram (Echo) or multigated acquisition (MUGA) scan.
• Pregnant or breasting feeding women or women of childbearing potential (WOCBP) with positive pregnancy test result
• WOCBP or men who are unwilling to practice highly effective contraception prior to the initial dose/start of the first treatment, during the study, and for at least 6 months after the last dose.
• NOTE: Other protocol defined inclusion/exclusion criteria apply