Aptevo reports 87% clinical benefit in frontline AML patients in RAINIER trial

Aptevo Therapeutics (APVO) reported new clinical results from its RAINIER frontline acute myeloid leukemia trial. The company is on track to complete the Phase 1b dose-optimization trial and select the recommended Phase 2 dose this year. As with the current study, the Phase 2 trial will dose mipletamig in combination with venetoclax and azacitidine. Across 31 evaluable frontline AML patients treated to date (includes data through RAINIER Cohort 5, plus 4 patients from the previously completed dose expansion trial), mipletamig in combination with venetoclax and azacitidine has demonstrated an 87% clinical benefit rate and an 81% remission rate, with results continuing to reflect a consistent profile of clinical activity and favorable safety as the dataset expands. With Cohort 5 complete, dosing has progressed through all previously evaluated mipletamig dose levels. The trial has now entered its final stage, which includes: Two final dose-level cohorts-Cohorts 6 and 7-representing the highest dose levels of mipletamig evaluated. Enrollment in Cohort 6 is nearing completion, and; Two groups of six additional patients will be enrolled at select dose levels, with the first enrolling concurrently with Cohort 6. These activities will complete the dataset required for RP2D selection and the planned Phase 2 regulatory interaction, with the trial on track for completion this year. “Our results demonstrate a consistent pattern of clinical activity and favorable safety across patients treated to date,” said Dirk Huebner, M.D., Chief Medical Officer of Aptevo Therapeutics. “As dose selection progresses, the focus is on identifying a Phase 2 dose that is supported by a complete and well-characterized dataset.”