• Diagnosis of MM as defined according to IMWG criteria (Rajkumar, 2014) with measurable disease at diagnosis

• Part 1 patients must be MRD positive, Part 2 patients can be MRD negative or MRD positive

• History of induction therapy for newly diagnosed MM, followed by high dose therapy and autologous stem cell transplant. Randomization must occur within 120 days from the stem cell transplant. For participants who receive consolidation therapy after ASCT, randomization must occur within 60 days of consolidation and within 7 months from ASCT.

• Partial Response or better according to IMWG criteria at the time of randomization

• Must have an archival bone marrow aspirate sample(s) to identify the dominant malignant (index) clone by central laboratory NGS test (ClonoSEQ assay) that is used to track MRD status. This sample should preferably be collected before induction treatment (eg, at diagnosis) or before transplant.

• ECOG performance status ≤1

• Resolved acute effects of any prior therapy to baseline severity or CTCAE Grade ≤ 1

• Not pregnant and willing to use contraception