BioNTech and DualityBio Announce Phase 3 Trial for Promising Breast Cancer Drug, BNT323

BioNTech SE and DualityBio have initiated a Phase 3 trial for BNT323/DB-1303, a promising antibody-drug conjugate targeting HER2-low metastatic breast cancer. The global trial focuses on patients with HR+ cancer who have progressed despite hormone therapy. The drug, previously successful in Phase 1/2 trials, offers potential for more effective, less toxic treatment options.

BioNTech SE and Duality Biologics announced a pivotal Phase 3 trial for their antibody-drug conjugate, BNT323/DB-1303, marking a significant advancement in breast cancer treatment. Targeting the Human Epidermal Growth Factor Receptor 2 (HER2), the trial aims to evaluate the drug's efficacy and safety in treating metastatic breast cancer. It plans to enroll 532 patients with Hormone Receptor-positive (HR+) and HER2-low metastatic breast cancer, who have progressed despite hormone therapy.

Prof. Özlem Türeci, Chief Medical Officer and Co-Founder at BioNTech, emphasized the potential of BNT323/DB-1303 to extend therapeutic options, stating, “For patients with advanced HR+/HER2-low breast cancers who progressed after primary therapy, single-agent palliative chemotherapy is the most common regimen to control the disease and reduce mortality. BNT323/DB-1303 has been designed with the aim to combine the selectivity of antibodies with the cancer cell-killing properties of chemotherapy, thereby aiming to minimize the toxicity of the chemotherapeutic agents for patients.”  

HER2-low breast cancer, which makes up about 40-45% of advanced metastatic cases, has been challenging to treat effectively. Traditional therapies targeting HER2 have often fallen short for patients with low levels of HER2 expression. However, BNT323/DB-1303 shows promise in bridging this treatment gap. This next-generation antibody-drug conjugate combines the specificity of antibodies with the cancer-destroying power of chemotherapy, potentially offering a more targeted and less toxic treatment option.

The Phase 3 trial (NCT06018337) will compare the effectiveness of BNT323/DB-1303 against standard single-agent chemotherapy in chemotherapy-naïve patients. The primary focus will be on progression-free survival, with secondary considerations including overall survival and response rates. This trial is a culmination of positive safety and efficacy data from earlier Phase 1/2 studies, which indicated significant anti-tumor activity, especially in heavily pretreated HER2-low breast cancer patients.

Dr. Vivian Gu, Chief Medical Officer at DualityBio, also highlighted the robust mechanism and preliminary efficacy shown by the drug in Phase 1/2 clinical studies. “The initiation of the Phase 3 trial marks an important step in the development of our next-generation ADC candidate with the first indication progressing into pivotal evaluation. Results from our Phase 1/2 clinical study indicate a robust mechanism of action of BNT323/DB-1303 and have demonstrated preliminary efficacy and a manageable safety profile.”

This Phase 3 trial represents a critical step for BioNTech and DualityBio in their strategic objective to advance BNT323/DB-1303 in treating multiple cancer indications with high unmet medical needs. The collaboration between these two companies, initiated in April 2023, focuses on accelerating the development of innovative antibody-drug conjugate therapeutics for solid tumors. This global trial will start in China and expand to the United States, Europe, and other regions, representing a critical development stage for the drug.

BNT323/DB-1303, developed from DualityBio’s Duality Immune Toxin Antibody Conjugates (DITAC) platform, targets the HER2 protein, often associated with aggressive cancer growth. The drug has shown promise in preclinical and clinical settings, demonstrating its potential across various solid tumor indications. The U.S. Food and Drug Administration (FDA) has granted it Fast Track and Breakthrough Therapy designations for the treatment of endometrial cancer in 2023.