This open-label, randomized, phase 3 trial (NCT02577406) compared enasidenib, an oral IDH2 inhibitor, with conventional care regimens (CCR) in patients aged ≥60 years with late-stage, mutant-IDH2 acute myeloid leukemia (AML) relapsed/refractory (R/R) to 2 or 3 prior AML-directed therapies. Patients were first preselected to a CCR (azacitidine, intermediate-dose cytarabine, low-dose cytarabine, or supportive care), and then randomized (1:1) to enasidenib 100 mg/day or CCR. The primary endpoint was overall survival (OS). Secondary endpoints included event-free survival (EFS), time to treatment failure (TTF), overall response rate (ORR), hematologic improvement (HI), and transfusion independence (TI). Overall, 319 patients were randomized to enasidenib (n=158) or CCR (n=161). Median age was 71 years. Median (range) enasidenib exposure was 142 days (3-1270) and CCR was 36 days (1-1166). One enasidenib (0.6%) and 20 CCR (12%) patients received no randomized treatment, and 30% and 43%, respectively, received subsequent AML-directed therapies during follow-up. Median OS with enasidenib vs CCR was 6.5 vs 6.2 months (HR [hazard ratio] 0.86; P=.23); 1-year survival was 37.5% vs 26.1%. Enasidenib meaningfully improved EFS (median 4.9 months, vs 2.6 months with CCR; HR 0.68; P=.008), TTF (median 4.9 vs 1.9 months, HR 0.53; P<.001), ORR (40.5% vs 9.9%; P<.001), HI (42.4% vs 11.2%), and RBC-TI (31.7% vs 9.3%). Enasidenib safety was consistent with prior reports. The primary study endpoint was not met but OS was confounded by early dropout and subsequent AML-directed therapies. Enasidenib provided meaningful benefits in EFS, TTF, ORR, HI, and RBC-TI in this heavily pretreated older mutant-IDH2 R/R AML population.
