On September 5, 2025 BioNTech SE (Nasdaq: BNTX, "BioNTech") and Duality Biologics (Suzhou) Co., Ltd. ("DualityBio") reported that the pivotal Phase 3 trial (NCT06265428) which DualityBio is conducting in China to evaluate trastuzumab pamirtecan (BNT323/DB-1303) versus trastuzumab emtansine (T-DM1) in patients with HER2-positive unresectable or metastatic breast cancer who have previously received trastuzumab and a taxane-based chemotherapy met its primary endpoint of progression free survival at a pre-specified interim analysis (Press release, BioNTech, SEP 5, 2025, View Source [SID1234655786]).
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Trastuzumab pamirtecan is a next-generation antibody-drug conjugate candidate targeting the cancer cell surface protein Human Epidermal Growth Factor Receptor 2 ("HER2"). The clinical trial compares the candidate to the approved ADC trastuzumab emtansine (T-DM1). Based on the results from the interim analysis which were shared by the Independent Data Monitoring Committee (IDMC) with DualityBio and evaluated by the Blinded Independent Central Review (BICR), DualityBio plans to discuss the next steps with the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA) of China regarding the submission of a Biologics License Application (BLA) of trastuzumab pamirtecan.
"This is a milestone in the fruitful collaboration with our colleagues at DualityBio," said Prof. Özlem Türeci, M.D., Chief Medical Officer and Co-Founder at BioNTech. "We believe that trastuzumab pamirtecan is an ADC candidate with enormous potential which makes it an important asset in our global oncology strategy including combinational approaches. It is the first of our late-stage oncology programs to meet its primary endpoint in a pivotal Phase 3 trial and also highlights our commitment to bringing novel oncology treatments with distinct profiles to patients."
"With over 350,000 new cases annually, breast cancer has a high incidence rate in China, making it the second most common malignant tumor among Chinese women," said Global Medical Officer of DualityBio, Dr. Hua Mu. "The positive Phase 3 data and trastuzumab pamirtecan meeting the primary endpoint at the interim analysis indicate the potential of the BNT323/DB-1303 program to become a new treatment option for breast cancer patients. Together with our partner BioNTech, we plan the development of trastuzumab pamirtecan in further tumor types towards BLA application in other regions including the United States and the European Union to maximize its potential for patients around the world."
This is the first positive Phase 3 data readout achieved in BioNTech’s and DualityBio’s strategic collaboration initiated in April 2023. The collaboration aims to accelerate the development of differentiated ADC therapeutics for solid tumors. In January 2024, the partners initiated a global Phase 3 DYNASTY-Breast02 trial program for trastuzumab pamirtecan in HR-positive, HER2-low metastatic breast cancer (DYNASTY-Breast02, NCT06018337) following positive Phase 1/2 safety and efficacy data in patients with HER2-expressing advanced solid tumors. BioNTech holds global commercial rights (excluding Mainland China, Hong Kong Special Administrative Region, and Macau Special Administrative Region), while DualityBio has commercial rights for Mainland China, Hong Kong Special Administrative Region, and Macau Special Administrative Region.
Further information for media: Fact Sheet about BNT323/DB-1303
About Trastuzumab Pamirtecan (BNT323/DB-1303)
Trastuzumab pamirtecan (BNT323/DB-1303) is a third-generation topoisomerase-1 inhibitor-based ADC targeting HER2 which was built from DualityBio’s proprietary Duality Immune Toxin Antibody Conjugates ("DITAC") platform. HER2 is a surface-expressed protein on solid tumors and has been linked to the aggressive growth and spread of cancer cells, making it a potential target for innovative cancer therapeutics. The candidate has exhibited antitumor activity in both HER2-positive and HER2-low tumor models as well as in several solid tumor indications, including patients with breast and endometrial cancers, as well as other advanced solid tumors. Preclinical data and preliminary clinical data for trastuzumab pamirtecan indicate its potential to target HER2 receptors on solid tumors irrespective of expression level with a manageable safety profile and a potentially expanded therapeutic window. Trastuzumab pamirtecan is currently being additionally evaluated in an ongoing Phase 1/2 trial (NCT05150691) in patients with advanced/metastatic solid tumors and in a pivotal Phase 3 trial (DYNASTY-Breast02; NCT06018337) in patients with Hormone Receptor-positive ("HR+") and Human Epidermal Growth Factor Receptor 2 ("HER2")-low, metastatic breast cancer that have progressed on hormone and/or cyclin-dependent kinase 4/6 ("CDK4/6") therapy. The BNT323/DB-1303 program received the Fast Track designation and Breakthrough Therapy designation from the U.S. Food and Drug Administration ("FDA") for the treatment of endometrial cancer in 2023.
About the Phase 3 trial NCT06265428
The Chinese, multi-center, randomized, controlled Phase 3 trial (NCT06265428) assesses the efficacy and safety of trastuzumab pamirtecan compared with trastuzumab emtansine in patients with HER2-positive unresectable or metastatic breast cancer who have been treated with trastuzumab and taxanes. A total of 228 patients were enrolled across 48 trial sites and were randomized 1:1 to receive trastuzumab pamirtecan or T-DM1, respectively. The trial’s primary endpoint is progression-free survival (PFS) as per RECIST 1.1 criteria, evaluated by Blinded Independent Central Review (BICR). Secondary endpoints include overall survival, objective response rate, duration of response, and safety.