07:23 AM EDT, 10/14/2025 (MT Newswires) -- Pfizer ( PFE ) said Tuesday that a phase 3 trial of its breast cancer drug Tukysa in combination with first-line standard maintenance therapy for metastatic HER2-positive breast cancer met its primary endpoint.

Treatment with Tukysa combined with trastuzumab and pertuzumab, given after chemotherapy-based induction, showed a statistically significant and clinically meaningful improvement in progression-free survival compared to placebo, according to Pfizer ( PFE ).

The company said the combination therapy was generally well tolerated, with a safety profile consistent with the known effects of the individual therapies.

Tukysa is currently approved in the US for use with trastuzumab and capecitabine in adults with advanced or metastatic HER2-positive breast cancer who have received at least one prior anti-HER2 therapy, the company said. The drug is not yet approved for first-line treatment, Pfizer ( PFE ) said.