Chinese biopharmaceutical company DualityBio (HK:9606) announced on Thursday that the Biologics License Application (BLA) for the investigational antibody-drug conjugate (ADC) trastuzumab pamirtecan ('T-Pam', also known as DB-1303 or BNT323), has been accepted for review by China's National Medical Products Administration (NMPA).

With the BLA filing, DualityBio is seeking approval for T-Pam as second-line treatment for patients with unresectable or metastatic HER2-positive breast cancer. The application is based on positive interim results from the pivotal Phase III clinical trial.

Conducted in China, the randomised, controlled, open-label, multicentre Phase III trial aims to evaluate the efficacy and safety of T-Pam compared to trastuzumab emtansine (T-DM1) in patients with HER2-positive unresectable or metastatic breast cancer who have previously received trastuzumab and taxane chemotherapy. As assessed by the Independent Data Monitoring Committee (IDMC), the trial met its primary endpoint of statistically significant improvement of progression-free survival (PFS, assessed by Blinded Independent Central Review, BICR) for T-Pam compared to T-DM1 at a pre-specified interim analysis.

T-Pam is a third-generation topoisomerase-1 inhibitor-based ADC targeting HER2, which is being developed by BioNTech and DualityBio. T-Pam was built from DualityBio's proprietary Duality Immune Toxin Antibody Conjugates (DITAC) platform.

The BNT323/DB-1303 programme received Fast Track designation and Breakthrough Therapy designation from the US Food and Drug Administration (FDA) for the treatment of endometrial cancer in 2023.