A Study Designed to Evaluate the Safety and Efficacy of Venetoclax Plus Dexamethasone (VenDex) Compared With Pomalidomide Plus Dexamethasone (PomDex) in Participants With t(11;14)-Positive Relapsed or Refractory Multiple Myeloma.

Inclusion Criteria

• Documented diagnosis of multiple myeloma (MM) based on standard International Myeloma Working Group (IMWG) criteria.
• Measurable disease at screening as defined per protocol.
• Has received at least 2 prior lines of therapy as described in the protocol.
• Has had documented disease progression on or within 60 days after completion of the last therapy.
• Has received at least 2 consecutive cycles of lenalidomide and be relapsed/refractory to lenalidomide, as defined per protocol.
• Has received at least 2 consecutive cycles of a proteasome inhibitor (PI).
• Has t(11;14)-positive status determined by an analytically validated fluorescent in situ hybridization (FISH) assay per centralized laboratory testing.
• An Eastern Cooperative Oncology Group (ECOG) performance status less than or equal to 2.
• Laboratory values (liver, kidney and hematology laboratory values) that meet criteria as described per protocol.

Exclusion Criteria

• History of treatment with venetoclax or another B-Cell Lymphoma (BCL)-2 inhibitor or pomalidomide.
• History of other active malignancies, including myelodysplastic syndromes (MDS), within the past 3 years (exceptions described in the protocol).
• Evidence of ongoing graft-versus-host disease (GvHD) if prior stem cell transplant (SCT).
• Prior treatment with any of the following: allogeneic or syngeneic SCT within 16 weeks prior to randomization; or autologous SCT within 12 weeks prior to randomization.
• Known central nervous system involvement of MM.
• Concurrent conditions as listed in the protocol.