Aptevo Reports 87% Clinical Benefit and 81% Remission in 31 Evaluable Frontline AML Patients Through Cohort 5, Substantially Outperforming Benchmark; RAINIER on Track for 2026 Completion and Phase 2 Dose Selection

Program Enters Final Stage of Dose Optimization Data Continue to Demonstrate Strong Clinical Activity and Favorable Safety Across an Expanding Frontline Dataset SEATTLE, WA / ACCESS Newswire / May 6, 2026 / Aptevo Therapeutics Inc. (Nasdaq:APVO) today reported new clinical results from its RAINIER frontline acute myeloid leukemia (AML) trial. The Company is on track to complete the Phase 1b dose-optimization trial and select the recommended Phase 2 dose (RP2D) this year.