Key Highlights

  • Aptevo Therapeutics shares closed down 34% at $1.71.
  • The company reported interim RAINIER data in frontline TP53-mutated AML showing 93% clinical benefit.
  • 79% CR/CRi was observed among 14 evaluable patients treated with mipletamig plus venetoclax and azacitidine.
  • The results compare favorably to a published 41% venetoclax/azacitidine remission benchmark.

Aptevo Therapeutics, Inc. (NASDAQ: APVO) shares closed down 34% at $1.71 despite reporting interim RAINIER data in frontline TP53-mutated AML showing 93% clinical benefit and 79% CR/CRi among 14 evaluable patients treated with mipletamig plus venetoclax and azacitidine.

What Happened

The results compare favorably to a published 41% venetoclax/azacitidine remission benchmark, with dose optimization expected to complete by year-end and regulatory interaction planned in the first half of 2027.

Market Reaction

Shares fell despite the favorable interim data, a decline that may reflect the small evaluable patient count of 14, or broader investor caution around early-stage data in a difficult-to-treat AML subtype.

Outlook

Completion of dose optimization by year-end and planned regulatory interaction in the first half of 2027 represent the next disclosed milestones for mipletamig in TP53-mutated AML.