Abstract
This nationwide, multicenter, open-label, single-arm study evaluated the efficacy and safety of the oral proteasome inhibitor (PI), ixazomib plus lenalidomide (LEN) and dexamethasone (DEX) (IRd) following injectable PI-based therapy for relapsed/refractory multiple myeloma (RRMM). Of 45 patients enrolled, 36 patients received IRd after achieving at least a minor response to 3 cycles of bortezomib or carfilzomib plus LEN + DEX (VRd, n=6; KRd, n=30). At median follow-up of 20.8 months, the 12-month event-free survival rate (primary endpoint) was 49% (90% CI: 35.9-62.0), counting 11 events of progressive disease/death, 8 dropouts and 4 missing response data. The 12-month progression-free survival (PFS) rate by Kaplan-Meier analysis (dropouts as censoring) was 74% (95% CI: 56-86). Median PFS and time to next treatment (95% CI) were 29.0 (21.3-NE) and 32.3 (14.9-35.4) months, respectively; median OS was not evaluable. The overall response rate was 73%, and 42% of patients had a very good partial response or better. Frequent (≥10% incidence) grade ≥3 treatment emergent adverse events were decreased neutrophil and platelet counts (n=7 [16%] each). Two deaths occurred (one during KRd treatment and one during IRd treatment), both due to pneumonia. IRd following injectable PI-based therapy was tolerable and efficacious in RRMM patients. TRIAL REGISTRATION NUMBER: NCT03416374; Date of registration: January 31, 2018.