Impact of prior lenalidomide or proteasome inhibitor exposure on the effectiveness of ixazomib-lenalidomide-dexamethasone for relapsed/refractory multiple myeloma: A pooled analysis from the INSURE study.

OBJECTIVES: To characterize the impact of prior exposure and refractoriness to lenalidomide or proteasome inhibitors (PIs) on the effectiveness and safety of ixazomib-lenalidomide-dexamethasone (IRd) in relapsed/refractory multiple myeloma (RRMM). METHODS: INSURE is a pooled analysis of adult RRMM patients who had received IRd in ≥2 line of therapy from three studies: INSIGHT MM, UVEA-IXA, and REMIX. RESULTS: Overall, 391/100/68 were lenalidomide-naïve/-exposed/-refractory and 37/411/110 were PI-naïve/-exposed/-refractory. Median duration of therapy (DOT) was 15.3/15.6/4.7 months and median progression-free survival (PFS) was 21.6/25.8/5.6 months in lenalidomide-naïve/exposed/refractory patients. Median DOT and PFS in PI-naïve/exposed/refractory patients were 20.4/15.2/6.9 months and not reached/19.8/11.4 months, respectively. The proportion of lenalidomide-naïve/exposed/refractory patients in INSIGHT and UVEA-IXA who discontinued a study drug due to adverse events (AEs) was ixazomib, 31.6/28.2/28.0% and 18.6/6.7/10.5%; lenalidomide, 21.9/28.2/16.0% and 16.1/6.7/10.5%; dexamethasone, 18.4/20.5/16.0% and 10.6/0/10.5%, respectively. The proportion of PI-naïve/exposed/refractory patients in INSIGHT and UVEA-IXA who discontinued a study drug due to AEs was: ixazomib, 44.4/28.8/27.8% and 22.2/16.7/15.7%; lenalidomide, 33.3/22.0/19.4% and 16.7/15.9/11.8%; dexamethasone, 33.3/17.4/16.7% and 16.7/9.5/7.8%, respectively. REMIX AE discontinuation rates were unavailable. CONCLUSION: IRd appeared to be effective in RRMM patients in routine clinical practice regardless of prior lenalidomide or PI exposure, with better outcomes seen in lenalidomide- and/or PI-nonrefractory versus refractory patients.