BioNTech Phase 2 cohort meets primary efficacy endpoint

BioNTech reported that the Phase 2 cohort of trastuzumab pamirtecan (BNT323) in advanced HER2‑expressing endometrial cancer met its primary endpoint, showing a confirmed objective response rate of 49.3% in previously checkpoint‑treated patients and 47.9% overall, with median progression‑free survival of 8.1 months.

BioNTech reported positive results from the primary analysis of a Phase 2 cohort evaluating trastuzumab pamirtecan (BNT323, also called DB-1303) in patients with HER2‑expressing, advanced endometrial cancer. The cohort is part of a global Phase 1/2a trial of the HER2‑targeted antibody‑drug conjugate. Patients had disease progression after first‑line chemotherapy, and some had prior checkpoint inhibitor treatment. The data were presented in an oral session at the 2026 Society of Gynecologic Oncology Annual Meeting in San Juan, Puerto Rico. Key results: - The Phase 2 cohort included 145 patients with advanced or metastatic HER2‑expressing endometrial cancer whose disease had progressed following first‑ or later‑line therapy. - The primary efficacy endpoint was evaluated in 73 patients who had prior checkpoint inhibitor treatment and confirmed HER2 status by central testing; the confirmed objective response rate (ORR) in this group was 49.3%. - Across all centrally tested patients the confirmed ORR was 47.9% and median progression‑free survival was 8.1 months. - Outcomes were reported as consistent across HER2 immunohistochemistry expression levels and irrespective of prior checkpoint inhibitor treatment. - The safety profile for trastuzumab pamirtecan monotherapy was reported as manageable. Summary: The analysis showed confirmed response rates near 48–49% and a median progression‑free survival of 8.1 months, which the company reported as clinically meaningful with a manageable safety profile. The data were presented at the 2026 Society of Gynecologic Oncology Annual Meeting. Undetermined at this time.