A Study of Oral Ixazomib Maintenance Therapy in Participants With Newly Diagnosed Multiple Myeloma (NDMM) Not Treated With Stem Cell Transplantation (SCT)

Inclusion Criteria

• Adult male or female participants 18 years or older with a confirmed diagnosis of symptomatic newly diagnosed multiple myeloma (NDMM) according to standard criteria.
• Completed 6 to 12 months (± 2 weeks) of initial therapy, during which the participant was treated to best response, defined as the best response maintained for 2 cycles after the M-protein nadir is reached.
• Documented major response (PR, VGPR, CR) according to the International Myeloma Working Group (IMWG) uniform response criteria, version 2011, after this initial therapy.
• Female participants who:
• Are postmenopausal for at least 1 year before the screening visit, OR
• Are surgically sterile, OR
• If they are of childbearing potential, agree to practice 2 effective methods of contraception, at the same time, from the time of signing the informed consent through 90 days after the last dose of study drug, OR
• Agree to practice true abstinence, when this is in line with the preferred and usual lifestyle of the participant. (Periodic abstinence [eg, calendar, ovulation, symptothermal, postovulation methods] and withdrawal are not acceptable methods of contraception.)

Male participants, even if surgically sterilized (that is, status postvasectomy), who:

• Agree to practice effective barrier contraception during the entire study Treatment period and through 90 days after the last dose of study drug, OR
• Agree to practice true abstinence, when this is in line with the preferred and usual lifestyle of the participant. (Periodic abstinence [example, calendar, ovulation, symptothermal, postovulation methods for the female partner] and withdrawal are not acceptable methods of contraception.)
• Voluntary written consent must be given before performance of any study-related procedure not part of standard medical care, with the understanding that consent may be withdrawn by the participant at any time without prejudice to future medical care.
• Complete documentation of the details of the initial therapy before randomization including cytogenetics and International Staging System (ISS) is available.
• Eastern Cooperative Oncology Group Performance Status of 0 to 2.
• Suitable venous access for the study-required blood sampling and consent for the specific amounts that will be taken.
• Is willing and able to adhere to the study visit schedule and other protocol requirements including blood sampling and bone marrow aspiration.
• Must meet the following clinical laboratory criteria at study entry:
• Absolute neutrophil count (ANC) greater than or equal to (≥) 1,000 per cubic millimeter (/mm^3) without growth factor support and platelet count ≥75,000/mm^3. Platelet transfusions to help participants meet eligibility criteria are not allowed within 3 days before randomization.
• Total bilirubin less than or equal to (≤) 1.5*the upper limit of the normal range (ULN).
• Alanine aminotransferase and aspartate aminotransferase ≤ 3*ULN.
• Calculated creatinine clearance ≥ 30 milliliter per minute (mL/min) (using the Cockcroft-Gault equation).

Exclusion Criteria

• Multiple myeloma that has relapsed after, or was not responsive to, initial therapy.
• Prior SCT.
• Radiotherapy within 14 days before randomization.
• Diagnosed or treated for another malignancy within 5 years before randomization or previous diagnosis with another malignancy. Participants with nonmelanoma skin cancer or carcinoma in situ of any type are not excluded if they have undergone complete resection.
• Female participants who are lactating and breastfeeding or have a positive serum pregnancy test during the Screening period.
• Major surgery within 14 days before randomization.
• Central nervous system involvement.
• Infection requiring intravenous (IV) antibiotic therapy or other serious infection within 14 days before randomization.
• Diagnosis of Waldenstrom's macroglobulinemia, polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin chan