BioNTech's ADC Candidate Delivers as Financial Pressures Mount

BioNTech's ADC candidate BNT323 shows 47.9% response rate in endometrial cancer trial, paving way for 2026 FDA submission as company shifts focus from COVID-19 vaccines.

BioNTech SE is charting a path toward its first oncology drug approval, buoyed by compelling clinical data for a key pipeline asset. The company's antibody-drug conjugate (ADC) candidate, trastuzumab pamirtecan (BNT323), demonstrated significant efficacy in a mid-stage trial for advanced endometrial cancer, setting the stage for a planned regulatory submission this year. This progress arrives as the German biotech navigates a steep decline in its COVID-19 vaccine revenue.

Presented at the Society of Gynecologic Oncology's 2026 Annual Meeting in San Juan, Puerto Rico, the Phase 2 results showed a confirmed objective response rate of 47.9% among centrally tested patients with HER2-expressing disease who had received prior chemotherapy. The median progression-free survival reached 8.1 months, with a median duration of response of 10.3 months. Notably, the therapy proved effective across a broad spectrum of patients. In those with the highest HER2 expression (IHC3+), the response rate jumped to 73.1%. Critically, the drug also showed clinically meaningful activity at lower HER2 expression levels (IHC1+ and IHC2+), potentially expanding its addressable patient population. The safety profile was deemed manageable, with grade 3 or higher treatment-related adverse events occurring in 46.9% of participants.

The data represent the largest dataset to date for a HER2-targeted ADC in this specific cancer indication. "These results are particularly noteworthy in a hard-to-treat subgroup," one analyst noted, pointing out that the response rate remained consistent at over 49% even in patients previously treated with checkpoint inhibitors.

Building on this momentum, BioNTech and its development partner DualityBio plan to submit a Biologics License Application (BLA) to the U.S. Food and Drug Administration in 2026, pending regulatory feedback. The candidate already holds Fast-Track and Breakthrough Therapy designations granted by the FDA in 2023. A global Phase 3 confirmatory trial, Fern-EC-01, comparing BNT323 to chemotherapy, is already underway. Further data is expected soon from the fully enrolled Phase 3 DYNASTY-Breast02 trial, which is evaluating the drug in HR-positive, HER2-low metastatic breast cancer; results are anticipated before the end of 2025.

This clinical advancement stands in stark contrast to the company's challenging financial transition. For the full year 2025, BioNTech reported a net loss of EUR 1.14 billion on revenue of just EUR 2.9 billion—a far cry from the EUR 17.3 billion peak during the height of its Comirnaty vaccine success. Management forecasts revenue will decline further in 2026 to between EUR 2.0 billion and EUR 2.3 billion. The stock, closing at EUR 79.40 on a recent Friday, is down nearly 4% year-to-date and trades well below its 52-week high of around EUR 106 reached in early 2025.

In a move to bolster its governance focus on oncology, BioNTech will ask shareholders at its virtual Annual General Meeting on May 15, 2026, to approve expanding its supervisory board from six to eight members. The two new seats are intended for specialists in oncology and clinical development, aiming to anchor the strategic pipeline more firmly at the highest level. The planned FDA filing this year offers investors a tangible near-term catalyst as the company seeks to prove its long-term vision beyond the pandemic.