DualityBio and BioNTech  Announce Phase 3 Trial of ADC Candidate BNT323/DB-1303 Met Primary Endpoint of Progression Free Survival in HER2-Positive Metastatic or Unresectable Breast Cancer

·       Data readout from trial NCT06265428 marks milestone in BioNTech and DualityBio’s strategic collaboration initiated in April 2023

·       DualityBio plans to submit data from the trial conducted in China to an upcoming medical conference and commence submission process for potential regulatory submission in China

·       Ongoing global Phase 3 trial with BNT323/DB-1303 in metastatic HER2-low breast cancer NCT06018337 is on track

MAINZ, Germany and SHANGHAI, China, September 5th, 2025 –  DualityBiologics (Suzhou) Co., Ltd. (“DualityBio”,HKEX:9606.HK) and BioNTech SE (Nasdaq: BNTX, “BioNTech”) today announced that the pivotal Phase 3 trial (DB-1303-O-3001) which DualityBio is conducting in China to evaluate trastuzumab pamirtecan (BNT323/DB-1303) met its primary endpoint of progression free survival (PFS) at pre-specified interim analysis in patients with HER2-positive unresectable or metastatic breast cancer who have previously received trastuzumab and a taxane-based chemotherapy.  

Trastuzumab pamirtecan is a next-generation antibody-drug conjugate (ADC) targeting the cancer cell surface protein Human Epidermal Growth Factor Receptor 2 (“HER2”). The trial NCT06265428 compares the candidate to the approved ADC trastuzumab emtansine (T-DM1). Based on the results from the interim analysis which were shared by Independent Data Monitoring Committee (IDMC) with DualityBio and evaluated by the Blinded Independent Central Review (BICR), DualityBio plans to initiate 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.

“The trastuzumab pamirtecan program is a pillar 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,” said Prof. Özlem Türeci, M.D., Chief Medical Officer and Co-Founder at BioNTech. “Trastuzumab pamirtecan was designed to combine the selectivity of antibodies with the cancer cell-killing properties of chemotherapy aimed to minimize the toxicity of the chemotherapeutic agents for improved treatment outcomes.”

“With over 350,000 new cases annually^[1], 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 antibody-drug conjugate therapeutics for solid tumors. In January 2024, the partners initiated another global Phase 3 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 BNT323/DB-1303

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 (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.of endometrial cancer in 2023.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 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 RESIST 1.1 criteria, evaluated by Blinded Independent Central Review (BICR). Secondary endpoints include overall survival, objective response rate, duration of response, and safety.

About BioNTech

Biopharmaceutical New Technologies (BioNTech) is a global next generation immunotherapy company pioneering novel investigative therapies for cancer and other serious diseases. BioNTech exploits a wide array of computational discovery and therapeutic modalities with the intent of rapid development of novel biopharmaceuticals. Its diversified portfolio of oncology product candidates aiming to address the full continuum of cancer includes mRNA cancer immunotherapies, next-generation immunomodulators and targeted therapies such as antibody-drug conjugates (ADCs) and innovative chimeric antigen receptor (CAR) T cell therapies. Based on its deep expertise in mRNA development and in-house manufacturing capabilities, BioNTech and its collaborators are researching and developing multiple mRNA vaccine candidates for a range of infectious diseases alongside its diverse oncology pipeline. BioNTech has established a broad set of relationships with multiple global and specialized pharmaceutical collaborators, including Bristol Myers Squibb, Duality Biologics, Fosun Pharma, Genentech, a member of the Roche Group, Genevant, Genmab, MediLink, OncoC4, Pfizer and Regeneron.

For more information, please visit www.BioNTech.com.

About DualityBio

DualityBio is a clinical-stage company focusing on the discovery and development of the next generation ADC therapeutics for patients with cancer and autoimmune diseases. DualityBio has successfully established a number of next generation Antibody-Drug Conjugate (ADC) technology platforms with global intellectual property rights. Building upon deep understanding of disease biology and translational capability, DualityBio has advanced 4[HM2]  assets into global clinical trials, and developed more than 10[HM3]  innovative product candidates which are currently in preclinical stage. Additionally, DualityBio is continuing evolving its novel protein engineering and ADC technology platforms for the next wave of “super ADC” molecules including diverse payload classes, bispecific ADCs and dual payload ADCs.

For more information, please visit www.dualitybiologics.com.