The purpose of this study is to assess the safety, tolerability and preliminary effectiveness of CC-92480 (BMS-986348) in novel therapeutic combinations for the treatment of Relapsed or Refractory Multiple Myeloma (RRMM).

Inclusion Criteria:

• Relapsed or refractory multiple myeloma (MM) and must:

  1. Have documented disease progression during or after their last myeloma therapy.
  2. For Part 1 Dose Finding: Be refractory to, intolerant to, or not a candidate for available, established therapies known to provide clinical benefit in MM; For Part 2 Dose Expansion: Be refractory to or have relapsed after the protocol specified number of prior lines of therapy that include an immunomodulatory drug (IMiD), a proteasome inhibitor, an anti-CD38 mAb, and a T-cell redirecting therapy (TRT, eg, a CAR-T or T-cell engaging bispecific treatment) unless the participant is not a candidate for TRT.

• Must have measurable disease.

• Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 or 1.

• Agree to follow the CC-92480 Pregnancy Prevention Plan (PPP).

Exclusion Criteria:

• Known active or history of central nervous system (CNS) involvement of MM

• Plasma cell leukemia; Waldenstrom's macroglobulinemia; polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes (POEMS) syndrome; or clinically significant light-chain amyloidosis.

• Impaired cardiac function or clinically significant cardiac disease

• Previous SARS-CoV-2 infection within 14 days for asymptomatic or mild symptomatic infections or 28 days for severe/critical illness prior to Cycle 1 Day 1 (C1D1)

• For Part 1: received prior therapy with CC-92480

• For Part 2: received prior therapy with CC-92480, tazemetostat, BMS-986158, or trametinib

• Previously received allogeneic stem-cell transplant at any time or received autologous stem-cell transplant within 12 weeks of initiating study treatment

• Received any of the following within 14 days prior to initiating study treatment:

  1. Plasmapheresis
  2. Major surgery
  3. Radiation therapy other than local therapy for myeloma associated bone lesions
  4. Use of any systemic anti-myeloma drug therapy

• Used any investigational agents within 28 days or 5 half-lives (whichever is shorter) prior to initiating study treatment

• COVID-19 vaccine within 14 days prior to C1D1

Other protocol-defined inclusion/exclusion criteria apply