BioNTech announce Phase 2 cohort of BNT323 met primary efficacy endpoint

BioNTech (BNTX) announced positive results from the primary analysis of a Phase 2 cohort evaluating trastuzumab pamirtecan, BNT323 or DB-1303, in patients with HER2-expressing, advanced endometrial cancer whose disease progressed on or after first-line chemotherapy with or without prior checkpoint inhibitor treatment. This cohort is part of a global Phase 1/2a clinical trial investigating the HER2-targeted antibody-drug conjugate, ADC, candidate trastuzumab pamirtecan in multiple solid tumors. The data demonstrated clinically meaningful efficacy and a manageable safety profile for trastuzumab pamirtecan monotherapy across all HER2 immunohistochemistry expression levels. Outcomes were consistent among patients regardless of prior checkpoint inhibitor treatment. The data will be presented today in an oral session at the 2026 Society of Gynecologic Oncology Annual Meeting on Women’s Cancers in San Juan, Puerto Rico. The analysis of the Phase 2 cohort included 145 patients with advanced or metastatic HER2-expressing endometrial cancer whose disease had progressed following first- or later lines of therapy. This cohort met its primary efficacy endpoint of objective response rate evaluated in 73 patients previously treated with checkpoint inhibitor therapy and confirmed HER2 status by central testing, showing a confirmed ORR of 49.3%. In all centrally tested patients the confirmed ORR was 47.9% with a median progression-free survival of 8.1 months.