BioNTech SE and Duality Biologics (Suzhou) Co., Ltd. announced that the first patient with metastatic breast cancer has been treated in a pivotal Phase 3 trial evaluating the efficacy and safety of the next-generation antibody-drug conjugate (“ADC”) candidate BNT323/DB-1303 targeting the Human Epidermal Growth Factor Receptor 2 (“HER2”), a cancer cell surface protein.
Breast cancer is the most commonly diagnosed cancer worldwide and the leading cause of death from malignant tumors in women globally.1,2 The breast cancer subtype, which is defined by the expression of hormone receptors ("hormone receptor-positive”, "HR+") and a low expression level of the HER2 protein ("HER2-low") on the cancer cell surface, accounts for approximately 40 % to 45 % of patients in advanced, metastatic disease stage.3 HER2 has been shown to be a suitable target structure for the treatment of breast cancers with intermediate and high HER2 expression.4 HER2-directed therapies have been ineffective in the past in patients with tumors with low expression levels of the protein.5 Recent studies have indicated that next-generation ADCs may have the potential to transfer the impact of HER2-directed therapies to HER2-low tumors.6
The global, multi-center, open-label, randomized Phase 3 trial (NCT06018337) will assess the efficacy and safety of BNT323/DB-1303 compared to standard-of-care single-agent chemotherapy in chemotherapy-naïve patients with HR+ and HER2-low metastatic breast cancer that have progressed on hormone therapy. The trial is expected to enroll 532 patients at more than 223 clinical sites worldwide, initially in China, followed by sites in the United States, Europe, and additional regions. The study’s primary endpoint is progression-free survival. Secondary endpoints include overall survival, objective response rate, duration of response, and safety.
The Phase 3 trial is based on positive safety and efficacy data from a Phase 1/2 study (NCT05150691) with BNT323/DB-1303 in patients with advanced/metastatic solid tumors. Data presented at ASCO 2023 demonstrated encouraging anti-tumor activity in heavily pretreated patients with HER2-low breast cancer with an objective response rate of 38.5% and a disease control rate of 84.6%. BNT323/DB-1303 was well tolerated with a manageable safety profile across all evaluated patients with advanced/metastatic solid tumors.
The milestone is in furtherance of BioNTech and DualityBio’s strategic objective to advance the product candidate into late-stage development in multiple high unmet medical need cancer indications. The Phase 3 trial initiation marks a major landmark 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. BioNTech will hold commercial rights globally (excluding Mainland China, Hong Kong Special Administrative Region, and Macau Special Administrative Region), while DualityBio will retain commercial rights for Mainland China, Hong Kong Special Administrative Region, and Macau Special Administrative Region.
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