A Study to Assess Adverse Events and Change in Disease Activity of Oral ABBV-453 Alone or in Combination With Subcutaneous and/or Oral Antimyeloma Agents in Adult Participants With Multiple Myeloma (MM)

Inclusion Criteria

• •Documented diagnosis of multiple myeloma (MM) based on standard international myeloma working group (IMWG) diagnostic criteria.
• •All participants must have measurable disease per central laboratory with at least 1 of the following assessed within 28 days prior to enrollment:
• •* Serum M-protein \>= 0.5 g/dL (\>= 5g/L); OR
• •* Urine M-protein \>= 200 mg/24 hours; OR
• •* For participants without measurable serum and urine M-protein: Serum free light chain (sFLC) ≥ 10 mg/dL (100 mg/L), provided sFLC ratio is abnormal.
• •B-cell lymphoma (BCL)-2 inhibitor treatment naïve.
• •t(11;14) positive status and/or BCL2 high status.
• •Substudy 1 Dose Escalation Cohorts and Substudy 2:
• •\-- Must be triple class exposed (PI, IMiD and anti-CD38) and have received 3 to 5 lines of prior antimyeloma therapy, and who have no other appropriate treatment options as deemed by the investigator.
• •Substudy 1 Dose Expansion Cohorts:
• •* Must be double class exposed (PI, IMiD) and have received 1 to 3 lines of prior antimyeloma therapy.