Phase I/II Study of Bendamustine and IXAZOMIB (MLN9708) Plus Dexamethasone in Relapsed/Refractory Multiple Myeloma

OVERVIEW: This Phase I/II study is designed to first identify doses of MLN9708 and bendamustine that are associated with an acceptable adverse event profile when delivered together in 28-day cycles. Additionally, the study aims to assess the efficacy of the combination in patients with relapsed/refractory multiple myeloma. Responders (stable disease or more),will continue to receive up to eight cycles total in the absence of further progressive disease.

OVERVIEW OF THE DOSE ESCALATION/DE-ESCALATION: This study aims to assess the combination's efficacy in patients with relapsed/refractory multiple myeloma. Responders (stable disease or more) will continue to receive up to eight cycles total in the absence of further progressive disease. The dose of MLN9708 will be fixed at 4 mg given on days 1, 8 and 15. Dexamethasone will be administered at 40 mg (oral) on Days 1, 8, 15 of each 28 day cycle. Dexamethasone administered as 40 mg oral on Days 1, 8, 15 of each 28 day cycle. Three doses of bendamustine will be evaluated (Dose 1: 70 mg/m^2, days 1 and 2; Dose 2: 80 mg/m^2. days 1 and 2; and Dose 3: 90 mg/m^2, days 1 and 2).

PHASE 1 DESIGN: A 3+3 design was employed. At each dose, three patients were initially evaluated. When no dose limiting toxicities were observed, the bendamustine dose will be increased.

PHASE 2 DESIGN: Design for Phase II portion of study: The MTD or a recommended phase 2 dose (RP2D) for the combination. The plan is to treat additional patients at that dose to assess efficacy and response to treatment. The investigators plan to enroll 19 patients (including those treated at the MTD in Phase I).