BioNTech, DualityBiologics' Late-Stage Trial of Metastatic Breast Cancer Therapy Meets Primary Endpoint; Severe, Fatal Events Reported

05:35 AM EDT, 10/26/2026 (MT Newswires) -- BioNTech (BNTX) and DualityBiologics' phase 3 trial of trastuzumab pamirtecan in metastatic breast cancer achieved its primary endpoint of demonstrating a statistically significant improvement in progression-free survival, but with severe and fatal events, the companies said Monday. Data on the secondary endpoint of overall survival were not yet mature as of the interim analysis, the companies said. Severe and fatal events were reported in a "small proportion of patients," along with a higher rate of interstitial lung disease compared with previous trials, they added. The companies plan to discuss the data and decide on their next steps, according to the statement. Shares of BioNTech were down more than 2% in premarket activity.