Higher Dose of CPX-351 Is Associated with Prolonged Hematologic Recovery: Results from an Interim Safety Analysis of the Randomized, Phase III AMLSG 30-18 Trial

Background: CPX-351, a liposomal formulation of daunorubicin and cytarabine in the fixed molar ratio (1:5), is approved for the treatment of adult patients (pts) with newly diagnosed acute myeloid leukemia (AML) with myelodysplasia-related changes and therapy-related AML (t-AML). To explore the potential benefit of CPX-351 in a broader indication, we initiated a randomized phase III study of CPX-351 vs “3+7” in pts ≥18 years (yrs) of age with AML and intermediate or adverse genetics according to 2017 European LeukemiaNet (ELN) risk categorization (AMLSG 30-18, NCT03897127). In the younger pts (18-60 yrs) we sought to investigate a higher dose of CPX-351. We here report data from an interim safety analysis for this higher CPX-351 dose. Methods: Pts are randomized to receive first induction cycle (ind 1) with either CPX-351 or daunorubicin + cytarabine (“3+7”: daunorubicin 60 mg/m2 on days 1, 2, 3 + cytarabine 200 mg/m2 on days 1-7); in pts aged 18-60 yrs (performance status 0-1) CPX-351 is given at a dose of 55 mg/m2 daunorubicin/125 mg/m2 cytarabine (125 U/m²; 1 U/m2=0.44 mg/m2 daunorubicin/1 mg/m2 cytarabine; days 1, 3, 5); pts >60 yrs receive the standard dose CPX-351 100 U/m² (days 1, 3, 5). There was no age-adapted dosing in the control arm. For induction cycle 2 (ind 2), pts on the CPX-351 arm receive the same dosage on day 1+2 only; pts on the control arm receive intermediate-dose cytarabine + daunorubicin (both in age-adapted dosing). Continuous assessment for safety is performed for two endpoints: 60-day mortality with a maximally tolerated rate (MTR) of 15%; and hematologic recovery times with i) neutropenia 4° and / or ii) thrombocytopenia 3° or 4° after each ind lasting longer than day 42 after start of treatment cycle (without evidence of persistent leukemia) with a MTR of 25%. Median hematologic recovery times were analyzed using Kaplan-Meier estimates, p-values are mentioned in a descriptive manner (log-rank test). Results: As of July 20, 2020, 36 patients have been randomized to the study (CPX-351, n=19; “3+7”, n=17) with following characteristics: de novo AML, n=27, secondary or t-AML, n=9; median age 60.5 yrs (range 47-75; ≤60 yrs, n=18; >60 yrs, n=18); intermediate and adverse risk genetics were found in 7 and 10 pts, respectively (not available yet, n=19). On the CPX-351 arm, 9 of 19 pts were ≤60 yrs of age and received the higher CPX-351 dose. So far, 36 pts received ind 1, 25 pts ind 2. Overall, the median time to neutrophil recovery w