Participants previously received a bortezomib-based triplet induction regimen, which included intravenous (IV) or subcutaneous (SC) bortezomib (biweekly or weekly) and IV or oral cyclophosphamide or oral lenalidomide and dexamethasone. All participants will be asked to take ixazomib 4 mg on Days 1, 4 and 8 and lenalidomide 25 mg from Day 1 through 21 and dexamethasone 40 mg on Days 1, 4, 8 and 21 in 28 day cycles until disease progression or unacceptable toxicity for up to 2 years. Dose modifications of ixazomib, and/or lenalidomide and/or dexamethasone are allowed at the discretion of the physician.