BioNTech and DualityBio announced on Apr. 13 that their investigational antibody-drug conjugate showed what they described as encouraging efficacy in a phase 2 study of patients with HER2-positive endometrial cancer.
The findings are important because they offer new data for patients who have already been treated with checkpoint inhibitor agents, a group for whom additional options are needed. The companies reported a 49.3% overall response rate among 73 such patients, while the response rate was slightly lower at 44.1% in the full sample of 143 participants.
According to the companies, trastuzumab pamirtecan demonstrated antitumor activity across all tested HER2 expression levels. The median duration of response was recorded at 10.3 months, and median progression-free survival was eight months regardless of prior checkpoint inhibition.
Trastuzumab pamirtecan is an anti-HER2 antibody-drug conjugate that uses a topoisomerase 1 inhibitor payload to induce tumor cell death. In addition to this mid-stage trial, BioNTech and DualityBio are also conducting a Phase 1/2 study for advanced or metastatic solid tumors involving this drug candidate.
Late-stage development is underway as well: trastuzumab pamirtecan is being evaluated in the Phase 3 Fern-EC-01 study for endometrial cancer with expected completion in November 2029, and in the Phase 3 DYNASTY-Breast02 trial for HER2-low, hormone receptor-positive metastatic breast cancer set to finish by July 2028. Detailed updates on these trials were not provided in the recent news release. BioNTech Chief Medical Officer Özlem Türeci said they are “continuing to advance trastuzumab pamirtecan, both as a monotherapy and in novel-novel treatment combination approaches.”
Trastuzumab pamirtecan was originally developed by Shanghai-based DualityBio before being acquired by BioNTech through an agreement signed in April 2023 that included $170 million upfront and up to $1.5 billion in milestones plus royalties covering two programs. Since then, both companies have moved quickly: within months they began late-stage development for breast cancer indications, while another asset from their partnership advanced into Phase 3 studies after positive early results.
