Aptevo Therapeutics reports early data for blood cancer therapy; shares fall

Aptevo expects to complete the dose-optimization portion of the study by year-end and plans regulatory discussions in the first half of 2027.

As of the last close, the stock was down 72.4% year to date.

The company said its experimental leukemia treatment, mipletamig, achieved a 93% clinical benefit rate in frontline acute myeloid leukemia (AML) patients with TP53 mutations, a hard-to-treat patient population, in an early-to-mid stage trial.

Of 14 evaluable TP53-mutated AML patients treated with mipletamig in combination with venetoclax and azacitidine, 13 experienced clinical benefit.

Eleven patients, or 79%, achieved complete remission or complete remission with incomplete hematologic recovery, including nine complete remissions.

TP53-mutated AML is associated with poor outcomes and lower response rates than other forms of the blood cancer. Last year, Aptevo reported a 100% remission rate in an earlier cohort of the trial.

Shares of drug developer Aptevo Therapeutics fell 21.2% to $2.05 in premarket trading after the company reported early data for its experimental blood cancer therapy.