Ixazomib as a Replacement for Carfilzomib and Bortezomib for Multiple Myeloma Patients

This is a phase 1/2, intra-patient, multicenter, open-label and non-randomized study to evaluate the efficacy and safety of ixazomib as a replacement for bortezomib or carfilzomib among multiple myeloma (MM) patients who have failed proteasome inhibitor (PI)-containing combination regimens. Patients will receive ixazomib once a week in place of bortezomib or carfilzomib in combination with an alkylating agent (melphalan or cyclophosphamide), anthracycline (pegylated doxorubicin \[PLD\]), immunomodulatory agent (lenalidomide, pomalidomide), ascorbic acid and/or a glucocorticosteroid (dexamethasone, prednisone or methylprednisolone) administered using the same dose(s) and schedule(s) as the last PI-containing regimen that the patients had received and failed. The total number of different prior bortezomib- or carfilzomib-containing regimens that will be evaluated is 10, reflecting those commonly used in the community as follows: * bortezomib + melphalan + prednisone * bortezomib + cyclophosphamide + ascorbic acid * bortezomib + cyclophosphamide + dexamethasone * bortezomib + PLD + dexamethasone * bortezomib + dexamethasone * carfilzomib + dexamethasone * bortezomib + lenalidomide + dexamethasone * bortezomib + pomalidomide + dexamethasone * carfilzomib + lenalidomide + dexamethasone * carfilzomib + pomalidomide + dexamethasone This study will enroll 60 patients who are refractory to a bortezomib- or carfilzomib-containing combination regimen, as demonstrated by progressive disease (PD) while being treated, or who have relapsed within 8 weeks from the last dose of bortezomib or carfilzomib in their last PI-containing combination regimen. Ixazomib will replace bortezomib or carfilzomib using the same PI-containing regimen the patients failed.The study will consist of: 1) a screening period; 2) up to eight 28-day treatment cycles; 3) a maintenance period; 4) a final assessment to occur 28 days after the end of the last treatment cycle; and 5) a follow-up period. Ixazomib will be administered PO at 4 mg on Days 1, 8 and 15 of a 28-day cycle to patients enrolled in seven regimens (bortezomib + melphalan + prednisone, bortezomib + dexamethasone, carfilzomib + dexamethasone, bortezomib + lenalidomide + dexamethasone, bortezomib + pomalidomide + dexamethasone, carfilzomib + lenalidomide + dexamethasone, carfilzomib + pomalidomide + dexamethasone). Subjects on those regimens receiving 4 mg of ixazomib from the beginning of the trial will continue to do so for the length of the study, unless they suffer from adverse events requiring dose reductions. For the other three regimens, bortezomib + cyclophosphamide + dexamethasone, bortezomib + cyclophosphamide + ascorbic acid, and bortezomib + PLD + dexamethasone, the MTD for ixazomib is unknown and intra-patient dose escalation will be performed to determine the specific MTD for each of them. For these three regimens, ixazomib will be administered on Days 1, 8 and 15 of a 28-day cycle at a starting dose of 3 mg in Cycle 1, and then intra-patient dose-escalation will proceed to 4 mg in Cycle 2. All other agents will be administered at the same schedule and dose intensity as those of the last PI-containing treatment the patient failed.