A Study of Oral Ixazomib Citrate (MLN9708) Maintenance Therapy in Participants With Multiple Myeloma Following Autologous Stem Cell Transplant

The investigational drug being tested in this study is called ixazomib citrate. Ixazomib citrate is being tested to slow disease progression and improve overall survival in people who have NDMM and who have had any type of positive response to induction therapy followed by HDT and ASCT. This study will look at the effect ixazomib citrate has on the length of time that participants are free of progressive disease (PD) and their overall survival (OS). The study enrolled 656 participants. Participants were randomly assigned (by chance, like flipping a coin) to one of the two treatment groups-which will remain undisclosed to the participant and study doctor during the study (unless there is an urgent medical need, or if the disease has progressed and the information is required for planning the next treatment): * Ixazomib citrate 3 mg for the first 4 cycles, then 4 mg for the remaining 22 cycles * Placebo (dummy inactive pill) - this is a capsule that looks like the study drug but has no active ingredient. All participants will be asked to take one capsule on Days 1, 8 and 15 of each 28-day cycle, for up to 26 cycles (approximately 24 months). This multi-center trial will be conducted globally. The overall time to participate in this study is up to 107 months. Participants will make 28 visits to the clinic during the treatment period and will continue to make visits after treatment has ended. During this initial follow up period, participants will be assessed for disease status with follow up every 12 weeks. After the next line of therapy begins, follow-up will occur every 12 weeks until death or termination of the study.