PFS was defined as the time from the date of randomization to the date of first documentation of progressive disease (PD) or death due to any cause according to International Myeloma Working Group (IMWG) criteria whichever occurs first. PD required one of the following: Increase of \>=25% from nadir in: Serum M-component and/or (the absolute increase must be \>=0.5 g/dL); Urine M-component and/or (the absolute increase must be \>=200 mg/24 hours); in participants without measurable serum and urine M-protein levels: the difference between involved and uninvolved free light chain (FLC) levels (absolute increase must be \> 10 mg/dL); Bone marrow plasma cell percentage: the absolute % must be \>10%; development of new bone lesions or soft tissue plasmacytomas or definite increase in the size of existing bone lesions or soft tissue plasmacytomas; hypercalcemia (corrected serum calcium \> 11.5 mg/dL or 2.85 mmol/L).

Combined Response Rate is the percentage of participants with Complete Response (CR), including stringent Complete Response (sCR), and Very Good Partial Response (VGPR) according to the International Myeloma Working Group (IMWG) criteria during the Induction Phase (Cycles 1-13, 28-day cycles). CR=negative immunofixation of serum and urine, disappearance of any soft tissue plasmacytomas and \<5% plasma cells in bone marrow. VGPR=serum and urine M-component detectable by immunofixation but not on electrophoresis or 90% reduction in serum M-component plus urine M-component \<100 mg/24 hour.

ORR is the percentage of participants with CR, VGPR or PR according to IMWG criteria. CR=negative immunofixation of serum and urine, disappearance of any soft tissue plasmacytomas and \<5% plasma cells (PC) in bone marrow. VGPR=serum and urine M-component detectable by immunofixation but not on electrophoresis or 90% reduction in serum M-component plus urine M-component \<100 mg/24 hour. PR=50% reduction of serum M-protein and reduction in 24 hour urine M-protein by 90% or \<200 mg/24 hour or decrease 50% difference between involved free light chain (FLC) levels or 50% reduction in bone marrow plasma cells if baseline percentage was 30%; and if present at Baseline, 50% reduction in the size of soft tissue plasmacytomas.

Minimal residual disease by multiparameter flow cytometry (MFC) \< 0.01%

Response was assessed using International Myeloma Working Group (IMWG) Criteria. VGPR is defined as serum and urine M-protein detectable by immunofixation but not on electrophoresis or 90% or greater reduction in serum M-protein plus urine M-protein level \<100 milligram (mg) per 24 hours. The percentage of participants were rounded off to the single decimal point.

An adverse event (AE) is defined as any untoward medical occurrence in a participant administered a pharmaceutical product; the untoward medical occurrence does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal (investigational) product whether or not it is related to the medicinal product. An SAE is any untoward medical occurrence that at any dose: a) results in death; b) is life-threatening (refers to an AE in which the participant was at risk of death at the time of the event. It does not refer to an event which hypothetically might have caused death if it were more severe); c) requires inpatient hospitalization or prolongation of an existing hospitalization; d) results in persistent or significant disability or incapacity; e) is a congenital anomaly/birth defect; f) is a medically important event.

An AE is defined as any untoward medical occurrence in a clinical investigation participant administered a drug; it does not necessarily have to have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (e.g., a clinically significant abnormal laboratory finding), symptom, or disease temporally associated with the use of a drug, whether or not it is considered related to the drug. The severity grade was evaluated as per the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) version 5.0. Grade 3: severe or medically significant but not immediately life-threatening; hospitalization or prolongation of hospitalization indicated; disabling; limiting self-care activities of daily living (ADL), Grade 4: life-threatening consequences; urgent intervention indicated. Grade 5 was: death related to AE.

Severity grade was evaluated based on CTCAE version 5.0. Grade 2: moderate symptoms; limiting instrumental activities of daily living. Grade 3: severe or medically significant; limiting self-care activities of daily living. Grade 4: life threatening consequences; urgent intervention indicated.

An AE means any untoward medical occurrence in a participant administered a pharmaceutical product; the untoward medical occurrence does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal (investigational) product whether or not it is related to the medicinal product.

An AE means any untoward medical occurrence in a participant administered a pharmaceutical product; the untoward medical occurrence does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal (investigational) product whether or not it is related to the medicinal product. Any AE interpreted by the investigator as a clinically significant event was reported.

DLT was defined as any of the following AEs that were considered by investigator to be possibly related to therapy: 1. Grade 4 neutropenia lasting at least 7 consecutive days; 2. Grade 3 neutropenia with fever and/or infection; 3. Grade 4 thrombocytopenia at least 7 consecutive days; 4. Grade 3 thrombocytopenia with clinically significant bleeding; 5. Platelet count \<10,000/mm\^3; 6. Grade 2 peripheral neuropathy with pain or ≥Grade 3 peripheral neuropathy; 7. Grade 3 or greater nausea and / or emesis despite the use of optimal anti-emetic prophylaxis; 8. Grade 3 or greater diarrhea that occurred despite maximal supportive therapy; 9. Any other Grade 3 or greater nonhematologic toxicity with the following exceptions: Grade 3 arthralgia/myalgia, \<1 week Grade 3 fatigue; 10. A delay of \>2 weeks in the subsequent cycle of treatment; 11. Other combination study drug-related nonhematologic toxicities ≥Grade 2 that, in the opinion of the investigator, required discontinuation of study drug.

An Adverse Event (AE) is defined as any untoward medical occurrence in a clinical investigation participant administered a drug; it does not necessarily have to have a causal relationship with this treatment. A SAE is defined as any untoward medical occurrence that at any dose: results in death, is life-threatening, requires inpatient hospitalization or causes prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect, or was a medically important event.

Clinically significant laboratory abnormalities were defined as any test results which were observed beyond the clinically acceptable limits as per the discretion of investigator. Clinical laboratory tests included chemistry, hematology and urinalysis tests.

The number of participants who meet markedly abnormal criteria for vital signs, included diastolic and systolic blood pressure, heart rate, oral temperature, respiratory rate, and body weight.

The RP2D is the maximum tolerated dose (MTD) or less. The MTD is defined as the dose range at which ≤ 1 of 6 evaluable participants experience dose limiting toxicities (DLT) within the first 28 days of treatment (end of Cycle 1).

VGPR or better response rate is defined as percentage of participants with a complete response (CR) and very good partial response (VGPR). Per International Myeloma Working Group Uniform Response Criteria (IMWG), CR: 1) Negative immunofixation on the serum and urine, 2) Disappearance of any soft tissue plasmacytomas and 3) \< 5% plasma cells in bone marrow. VGPR: Serum and urine M-protein detectable by immunofixation but not on electrophoresis or 90% or greater reduction in serum M-protein plus urine M-protein level \< 100 mg per 24 hour.

An Adverse Event is defined as any untoward medical occurrence in a clinical investigation participant administered a drug; it does not necessarily have to have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (eg, a clinically significant abnormal laboratory finding), symptom, or disease temporally associated with the use of a drug, whether or not it is considered related to the drug. A treatment-emergent adverse event (TEAE) is defined as an adverse event with an onset that occurs after receiving study drug. A Serious Adverse Event (SAE) was any experience that suggests a significant hazard, contraindication, side effect or precaution that: results in death, is life-threatening, required in-patient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect or is medically significant.

Neurotoxicity is graded using participant responses to 11 functional questions on a 5-point scale, where 0=Not at all and 4=Very much, using the Functional Assessment of Cancer Therapy/Gynecology Oncology Group - Neurotoxicity Questionnaire, Version 4.0(14). Neurotoxicity subscale is a sum of 11 reversed item scores where each original score is transformed as (4 - score). The highest possible score is 44, and a higher score indicates more neurotoxicity.

MTD was highest dose of ixazomib given with combination drugs, at which \<=1 of 6 participants experienced dose-limiting toxicity (DLT) during Cycle 1 of Phase 1. DLT defined as any of following considered possibly related to therapy: Grade 4 neutropenia (absolute neutrophil count \[ANC\] \<500 cell per cubic millimeter \[cells/mm\^3\]) for \>7 days; Grade 3 neutropenia with fever or infection; Grade 4 thrombocytopenia for \>7 days; Grade 3 thrombocytopenia with clinically significant bleeding; platelet count \<10,000/mm\^3; Grade 2 peripheral neuropathy with pain or \>=Grade 3 peripheral neuropathy; \>=Grade 3 nausea/emesis, diarrhea controlled by supportive therapy; any \>=Grade 3 nonhematologic toxicity except Grade 3 arthralgia/myalgia; or \<1 week Grade 3 fatigue; delay in initiation of the subsequent therapy cycle by \>14 days; \<=80% lenalidomide doses administered due to other \>=Grade 2 combination study drug-related nonhematologic toxicities requiring therapy discontinuation.

The RP2D of ixazomib was determined after the evaluation of the available data from the phase 1 portion of the trial which included, but was not limited to analyses of efficacy results, toxicity characterization, all grades peripheral neuropathy, and treatment discontinuation. The maximum number of cycles received was 83 cycles (approximately up to 2037 days).

An Adverse Event (AE) is defined as any untoward medical occurrence in a clinical investigation participant administered a drug; it does not necessarily have to have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (example, a clinically significant abnormal laboratory finding), symptom, or disease temporally associated with the use of a drug, whether or not it is considered related to the drug. A SAE is an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; or congenital anomaly; or a medically important event. A TEAE is defined as an adverse event with an onset that occurs after receiving study drug.

Laboratory tests included chemistry, hematology and urinalysis. Abnormal laboratory value was assessed as an AE if the value lead to discontinuation or delay in treatment, dose modification, therapeutic intervention, or was considered by the investigator to be a clinically significant change from baseline. A treatment-emergent adverse event (TEAE) is defined as an adverse event with an onset that occurs after receiving study drug.

TEAE related to neurotoxicity grading based on common terminology criteria for adverse events (CTACE) version 4.03 are reported. Grade 1= mild; Grade 2= moderate; within normal limits, Grade 3= severe or medically significant but not immediately life-threatening; Grade 4= life-threatening consequences; urgent intervention indicated; Grade 5= death. Only TEAEs related to neurotoxicity with values are reported.

Vital signs included body temperature, blood pressure and heart rate.

CR as per International Myeloma Working Group (IMWG) uniform criteria is defined as negative immunofixation on the serum and urine and disappearance of soft tissue plasmacytomas and \<5% plasma cells in bone marrow. VGPR as per IMWG criteria is defined as serum and urine M-protein detectable by immunofixation but not on electrophoresis or 90% or greater reduction in serum M-protein plus urine M-protein level \<100 mg per 24 hours. VGPR was applicable only to participants who had measurable disease defined by at least 1 of the following 3 measurements: Serum M-protein greater than or equal to (\>=)1 g/dL; Urine M-protein \>=200 mg/24 hours; Serum FLC assay level \>=10 mg/dL, provided serum FLC ratio was abnormal.

An Adverse Event (AE) is defined as any untoward medical occurrence in a clinical investigation participant administered a drug; it does not necessarily have to have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (example, a clinically significant abnormal laboratory finding), symptom, or disease temporally associated with the use of a drug, whether or not it is considered related to the drug. As per Common Terminology Criteria for Adverse Events v4.0 (CTCAE), Grade 3 = AE with severe or medically significant but not immediately life-threatening; hospitalization or prolongation of hospitalization indicated; disabling; limiting self-care activities of daily living. Grade 4 = AE with life-threatening consequences; urgent intervention indicated and Grade 5 = Death related to AE.

A SAE is an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; or congenital anomaly; or a medically important event.

An Adverse Event (AE) is defined as any untoward medical occurrence in a clinical investigation participant administered a drug; it does not necessarily have to have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (example, a clinically significant abnormal laboratory finding), symptom, or disease temporally associated with the use of a drug, whether or not it is considered related to the drug. A TEAE is defined as an adverse event with an onset that occurs after receiving study drug.