A Study of Ixazomib, Given With Dexamethasone in Adults With Multiple Myeloma

The drug being tested in this study is called Ixazomib. Ixazomib is being tested to treat people who have relapsed and/or refractory multiple myeloma (RRMM). This study will compare the efficacy and safety in participants who take ixazomib and dexamethasone to pomalidomide and dexamethasone. It is an open-label, Phase 2 study. The study will enroll approximately 120 participants. Participants will receive: * Ixazomib 4 mg + dexamethasone 20 mg (or 10 mg if participant is aged \>=75 years) OR * Pomalidomide 4 mg + dexamethasone 40 mg (or 20 mg if participant is aged \>=75 years) All participants will be asked to take either ixazomib plus dexamethasone (in cases where only 4 mg tablets for dexamethasone are available, the following dexamethasone schedule is recommended for participants aged \>=75 years: 12 mg dexamethasone will be given on Days 1, 8, 15, and 22 of every 28-day cycle; and 8 mg dexamethasone will be given on Days 2, 9, 16, and 23 of every 28-day cycle) or pomalidomide 4 mg + dexamethasone 40 mg at recommended doses. This multi-center trial will be conducted worldwide. The overall time to participate in this study is approximately 28 months after the first participant enters the study. Participants will make multiple visits to the clinic, and will be contacted for progression free-survival (PFS) follow-up, in case of study drug discontinuation for up to 4 years from first dose administration. After disease progression, participants will be followed-up for overall survival (OS) every 12 weeks until death or up to 4 years. Alternative methods for administering study procedures/assessments may be considered when it is not possible for the participants to come to the study site due to extenuating circumstances (e.g., due to the COVID-19 pandemic).