Aptevo reports 79% AML remission rate

• Aptevo Therapeutics (NASDAQ:APVO) reported a 93% clinical benefit rate for its mipletamig triplet regimen in frontline TP53-mutated AML patients.
• Eleven of 14 evaluable patients achieved complete remission or complete remission with incomplete hematologic recovery.
• The ongoing RAINIER Phase 1b/2 trial is expected to complete dose optimization by year-end, with regulatory discussions planned for the first half of 2027.

Aptevo Therapeutics (NASDAQ:APVO) reported clinical results showing that 13 of 14 evaluable frontline TP53-mutated acute myeloid leukemia (AML) patients treated with its mipletamig triplet regimen achieved clinical benefit.

The company reported that 11 patients, or 79%, achieved complete remission (CR) or complete remission with incomplete hematologic recovery (CRi), compared with a published 41% composite remission rate for venetoclax plus azacitidine alone in treatment-naïve TP53-mutated AML with poor-risk cytogenetics.

Aptevo reported results from its mipletamig combination with venetoclax and azacitidine, with the company continuing enrollment and dose optimization in the ongoing RAINIER Phase 1b/2 clinical trial.

The company stated that the trial is expected to complete its dose optimization phase by year-end, with regulatory interaction planned during the first half of 2027, while mipletamig maintains orphan drug designation for AML.

Aptevo said mipletamig is designed to target CD123-expressing leukemia cells while aiming to reduce cytokine release syndrome risk, a potential immune-related treatment complication.

The company develops targeted immunotherapies, including bispecific antibody candidates, with mipletamig as its lead wholly owned clinical program focused on AML treatment.