Aptevo Posts 87% Clinical Benefit and 81% Remission in Frontline AML Trial
Aptevo's RAINIER Phase 1b trial in 31 frontline AML patients showed an 87% clinical benefit rate and 81% remission rate, including 65% complete remissions and 55% achieving MRD-negative status. The trial is entering its final dose-optimization stage with cohorts 6 and 7 to select the Phase 2 dose by year-end.
1. Efficacy Results in Frontline AML
Across 31 evaluable frontline AML patients treated to date, mipletamig plus venetoclax and azacitidine delivered an 87% clinical benefit rate (CR/CRi/PR) and an 81% remission rate (CR/CRi). Notably, 65% achieved complete remission, 55% reached MRD-negative status, 36% of remissions occurred in TP53-mutated patients, and six patients proceeded to allogeneic stem cell transplant with no cytokine release syndrome reported.
2. Progression to Final Dose-Optimization Stages
With Cohort 5 complete, the RAINIER trial has evaluated all previously studied mipletamig dose levels and entered its final stage. Enrollment in Cohort 6 is nearing completion, and two additional groups of six patients each will be dosed at select levels, completing the dataset required for selecting the recommended Phase 2 dose (RP2D).
3. Phase 2 Dose Selection and Next Steps
Data from cohorts 6 and 7 will support Aptevo's planned regulatory interaction and RP2D selection this year. The Phase 2 trial will evaluate mipletamig in combination with venetoclax and azacitidine, leveraging the consistent activity and favorable safety profile demonstrated to date.