Alliance A061202: ixazomib, pomalidomide, and dexamethasone for patients with lenalidomide-refractory MM in first relapse.

ABSTRACT: Optimal therapy for the growing number of patients with lenalidomide (LEN)-refractory multiple myeloma in their first relapse remains poorly defined. We therefore undertook a randomized phase 2 study to evaluate the efficacy and safety of combining the oral proteasome inhibitor ixazomib (IXA) with pomalidomide (POM) and dexamethasone (DEX) in this patient population. The overall response rate (ORR) for POM-DEX was 43.6%, and for IXA-POM-DEX, it was 63.2%. The depth of response, measured by the attainment of at least a very good partial response, favored triplet therapy over doublet therapy (28.9% vs 5.1%; P = .0063). A preplanned interim analysis after 75% of the progression events had occurred demonstrated an improvement in progression-free survival (PFS) that favored IXA-POM-DEX and that crossed the predefined boundary of superiority, leading to release of the study results. With additional follow-up, the median PFS for POM-DEX was 7.5 months (95% confidence interval [CI], 4.8-13.6 months) vs 20.3 months for IXA-POM-DEX (95% CI, 7.7-26.0 months; hazard ratio, 0.437; upper 90% bound = 0.657). The ORR and median PFS for 26 of 30 eligible patients who crossed over from the doublet to the triplet therapy at disease progression was 23.1% and 5.6 months, respectively. Overall survival was similar between the 2 groups. More hematologic toxicities were seen with the triplet therapy, but nonhematologic adverse events were similar between the 2 arms. Our data support further testing of this all-oral triplet therapy in comparison with current standard triplet therapy in the context of phase 3 studies for patients with LEN-refractory disease at first relapse. This trial was registered at www.clinicaltrials.gov as #NCT02004275.

A phase I/II study of ixazomib, pomalidomide, and dexamethasone for lenalidomide and proteasome inhibitor refractory multiple myeloma (Alliance A061202).

Preclinical studies have demonstrated activity of the oral proteasome inhibitor (PI) ixazomib (IXA) in bortezomib-resistant multiple myeloma (MM) and synergy with immunomodulatory drugs. We therefore conducted a phase I/II study to establish the safety and preliminary efficacy of IXA with pomalidomide (POM) and dexamethasone (DEX) in lenalidomide (LEN)/PI-refractory MM. Dose escalation established a 4 mg dose of POM and IXA and 20/40 mg dose of DEX as the maximum tolerated dose. The phase II portion of the trial was redesigned and started anew after six patients had been randomized to IXA-POM-DEX due to a rapidly changing treatment landscape. Among the 29 evaluable LEN/PI-refractory patients treated with IXA-POM-DEX in phase I/II, the overall response rate (partial response or better) was 51.7% with a median duration of response of 16.8 months (range 56 days to 4.1 years), median progression-free survival of 4.4 months (95% confidence interval [CI]: 3.0-18.4), and median overall survival of 34.3 months (95% CI: 19.2 to not reached). Hematologic, gastrointestinal, and constitutional adverse events were common and consistent with the side-effect profiles of the individual agents. Our results support further evaluation of this all-oral regimen in relapsed/refractory MM.