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

PFS was defined as the time from the date of randomization to the date of first documentation of PD, as evaluated by an independent review committee (IRC) according to International Myeloma Working Group (IMWG) criteria, or death due to any cause, whichever occurred first. PD was defined as ≥25% increase from lowest value in: serum/urine M component; participants without measurable serum and urine M-protein levels, the difference between involved and uninvolved free light chain (FLC) levels must be >10 milligrams per deciliter (mg/dL); participants without measurable serum, urine M-protein levels and FLC levels, bone marrow plasma cell percent must have been ≥10%; new bone lesions/soft tissue plasmacytomas development/existing bone lesions/soft tissue plasmacytomas size increase; hypercalcemia development.

OS was measured as the time from the date of randomization to the date of death.

Response was assessed according to IMWG criteria. Best response includes partial response (PR), very good partial response (VGPR) and complete response (CR). PR as per IMWG criteria is 50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to less than (<)200 milligrams (mg) per 24 hours. VGPR is serum and urine M-protein detectable by immunofixation but not on electrophoresis or ≥90% reduction in serum M-protein plus urine M-protein level <100 mg per 24 hours. CR is negative immunofixation of serum and urine and disappearance of soft tissue plasmacytomas and <5% plasma cells in bone marrow. Stringent CR (sCR) is CR and normal FLC ratio and absence of clonal plasma cells (PCs) by immunohistochemistry or 2- to 4-color flow cytometry. The decimal values of percentages were subjected to rounding off.

TTP is defined as the time from the date of randomization to the date of first documentation of PD, using IMWG criteria. PD is defined as ≥25% increase from lowest value in: serum/urine M-component; participants without measurable serum and urine M-protein levels, the difference between involved and uninvolved FLC levels must be >10mg/dL; participants without measurable serum, urine M-protein levels and FLC levels, bone marrow plasma cell percent must be ≥10%;new bone lesions/soft tissue plasmacytomas development/existing bone lesions/soft tissue plasmacytomas size rise; hypercalcaemia development. Participants without documentation of PD at the time of analysis were censored at the date of last response assessment that is stable disease or better.

PFS2 is defined as the time from the date of randomization to the date of objective disease progression on next line treatment or death from any cause (whichever occurs first). PD is defined as ≥25% increase from lowest value in: serum/urine M-component; participants without measurable serum and urine M-protein levels, the difference between involved and uninvolved FLC levels must be >10 mg/dL; participants without measurable serum, urine M-protein levels and FLC levels, bone marrow plasma cell percent must be ≥10%; new bone lesions/soft tissue plasmacytomas development/existing bone lesions/soft tissue plasmacytomas size rise; hypercalcaemia development.

Time to start of the next line of therapy was defined as the time from the date of randomization to the date of initiation dose of the next line of antineoplastic therapy following study treatment or death due to any cause, whichever occurred first. Participants who never took antineoplastic therapy were censored at the date of last contact or death.

Time to end of the next line of therapy was defined as the time from the date of randomization to the date of last dose of the next line of antineoplastic therapy following study treatment or death due to any cause, whichever occurred first or date of last contact for participants who never took antineoplastic therapy.

Duration of the next line of therapy was defined as the time from the date of the first dose of the next line of therapy to the date of the last dose of the next antineoplastic therapy following study treatment or death due to any cause, whichever occurred first. Duration of the next line of therapy was analyzed on those participants who received the next line of therapy following the study treatment and duration was summarized using Kaplan-Meier method.

The decimal values of percentages were subjected to rounding off.

MRD negativity (MRD-) is defined as absence of MRD and MRD positivity (MRD+) is defined as presence of MRD. The conversion rate from MRD positive to MRD negative was assessed and reported. Bone marrow aspirates and blood samples were sent to a central laboratory and were assessed for MRD using flow cytometry and a sequencing methodology.

MRD negativity is defined as absence of MRD and MRD positivity is defined as presence of MRD. The maintenance of MRD negativity up to the end of treatment was assessed and reported in participants converting from MRD+ at Baseline to MRD negative. Bone marrow aspirates and blood samples were sent to a central laboratory and were assessed for MRD using flow cytometry and a sequencing methodology.

PFS is defined as the time from the date of randomization to the date of first documentation of PD as evaluated by an IRC according to IMWG criteria, or death due to any cause, whichever occurred first, assessed for up to 107 months in this outcome measure.

OS was measured as the time from the date of randomization to the date of death, assessed for up to 107 months in this outcome measure.

High-risk population included but was not limited to participants carrying deletion (del)17, t(4:14), t(14:16), amplification (ampl) 1q, del13, or del1p. OS was measured as the time from the date of randomization to the date of death.

High-risk population included but not be limited to participants carrying deletion (del)17, t(4:14), t(14:16), amplification (ampl) 1q, del13, or del1p. PFS was defined as the time from the date of randomization to the date of first documentation of PD, as evaluated by an independent review committee according to IMWG criteria, or death due to any cause (whichever occurs first). PD is defined as ≥25% increase from lowest value in: serum/urine M-component; participants without measurable serum and urine M-protein levels, the difference between involved and uninvolved FLC levels must be >10mg/dL; participants without measurable serum, urine M-protein levels and FLC levels, bone marrow plasma cell percent must be ≥10%;new bone lesions/soft tissue plasmacytomas development/existing bone lesions/soft tissue plasmacytomas size rise; hypercalcaemia development.

ECOG performance status assesses a participant's performance status on a 6-point scale ranging from 0=fully active/able to carry on all pre-disease activities without restriction; 1=restricted in physically strenuous activity, ambulatory/able to carry out light or sedentary work; 2=ambulatory (>50% of waking hours), capable of all self-care, unable to carry out any work activities; 3=capable of only limited self-care, confined to bed/chair >50% of waking hours; 4=completely disabled, cannot carry on any self-care, totally confined to bed/chair; 5=dead. Lower scores indicate improvement.

An adverse event (AE) was defined as any untoward medical occurrence in a clinical investigation subject administered a drug. An AE can be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a drug whether or not it is considered related to the drug. A TEAE was defined as an AE that started or worsened after first study drug administration and within 30 days of last dose of study drug. An SAE was defined as any untoward medical occurrence that at any dose resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability or incapacity, was a congenital abnormality or birth defect, an important medical event.

Laboratory tests included chemistry, hematology and urinalysis. Abnormal laboratory value was assessed as an AE if the value led 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 TEAE was defined as an AE that started or worsened after first study drug administration and within 30 days of last dose of study drug.

The EORTC QLQ-C30 is a 30-item questionnaire used to assess the health-related quality of life of cancer patients. GHS/QoL domain is based on questions 29 ("How would you rate your overall health during the past week?") and 30 ("How would you rate your overall quality of life during the past week?") of the EORTC QLQ-C30 where the study participants' self-reported responses to the questions on a 7-point scale (1=very poor to 7=excellent). The raw GHS/QoL domain scores were linearly transformed to a scale ranging 0 (worse outcome) to 100 (best outcome), with higher scores indicating better quality of life. The change from baseline in EORTC QLQ-C30 GHS/QoL domain was evaluated by treatment group.

Plasma concentrations of the complete hydrolysis product of ixazomib citrate (ixazomib) were measured using a validated Liquid Chromatography-tandem Mass Spectrometry (LC/MS/MS) assay.

Peripheral neuropathy is defined as the TEAE in the high-level term of peripheral neuropathies not elsewhere classified (NEC) according to Medical Dictionary for Regulatory Activities (MedDRA). A PN event is considered as improved if the event improves from the maximum grade. That is, all the grades recorded after the maximum grade is less than the maximum grade. Time to improvement is defined as the time from the initial onset date (inclusive) of the maximum grade to the first onset date that the toxicity grade is below the maximum grade with no higher grade thereafter, or the resolution date, whichever occurs first.

PN is defined as the treatment-emergent adverse event in the high-level term of peripheral neuropathies not elsewhere classified (NEC) according to the Medical Dictionary for Regulatory Activities (MedDRA). A PN event is considered as resolved if its final outcome is resolved with no subsequent PN event of the same preferred term occurring on the resolution date or the day before and after. A PN event is considered as improved if the event improves from the maximum grade. That is, all the grades recorded after the maximum grade is less than the maximum grade. Time to improvement is defined as the time from the initial onset date (inclusive) of the maximum grade to the first onset date that the toxicity grade is below the maximum grade with no higher grade thereafter, or the resolution date, whichever occurs first.