This will be a phase 1/2, multicenter, 2-arm, open-label study using the oral formulation of IXAZOMIB when added to standard melphalan and prednisone (MP) treatment. Both phases of the study will include patients who have newly diagnosed multiple myeloma and are ineligible for high-dose therapy plus stem cell transplantation because of age (≥65 years of age) or coexisting conditions and for whom standard MP treatment is indicated.