Inclusion Criteria: - Participants must have a diagnosis of multiple myeloma with relapsed and/or refractory disease. - Participants must have confirmed progressive disease on or within 12 months (measured from the last dose) of completing treatment with the last anti-myeloma treatment regimen before study entry. - Participants in Part A and Part B Cohort 1 must have received at least 3 prior anti-myeloma treatment regimens, including a proteasome inhibitor and immunomodulatory agent. - Participants must have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. - Participants must have adequate organ function. Exclusion Criteria: - Participants must not have any known active or history of central nervous system (CNS) involvement of multiple myeloma. - Participants must not have active or history of plasma cell leukemia, Waldenstrom's macroglobulinemia, POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes) syndrome, or clinically significant amyloidosis. - Participants must not have a history or presence of clinically significant CNS pathology such as seizure disorder, aphasia, stroke, severe brain injury, dementia, Parkinson's disease, or cerebellar disease, or presence of clinically active psychosis. Other protocol-defined inclusion/exclusion criteria apply