BioNTech and DualityBio have begun a Phase III trial of BNT323/DB-1303, an antibody-drug conjugate (ADC) candidate for the treatment of metastatic breast cancer.
This follows the release of Phase I/II trial data on BNT323/DB-1303 demonstrating safety and early signs of efficacy in patients with advanced solid tumours expressing human epidermal growth factor receptor 2 (HER2).
The trial aims to enrol 532 subjects with hormone receptor-positive (HR+) and HER2-low metastatic breast cancer across clinical sites.
It will initially be carried out in China, before expanding to the US, Europe and other regions.
The trial's primary endpoint is progression-free survival, with its secondary endpoints including overall survival, safety, duration of response and objective response rate.
The Phase I/II data showed an objective response rate of 38.5% and an 84.6% disease control rate in heavily pretreated HER2-low breast cancer patients.
BNT323/DB-1303 was found to be well-tolerated with a manageable safety profile.
DualityBio chief medical officer Vivian Gu said: “The initiation of the Phase III 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 I/II clinical study indicate a robust mechanism of action of BNT323/DB-1303 and have demonstrated preliminary efficacy and a manageable safety profile.
“We look forward to further advancing this differentiated ADC candidate.”
BNT323/DB-1303 is a third-generation topoisomerase-1 inhibitor-based ADC developed from DualityBio's Duality Immune Toxin Antibody Conjugates (DITAC) platform.
Last year, the drug received fast track and breakthrough therapy designations from the US Food and Drug Administration (FDA) for endometrial cancer treatment.
BioNTech chief medical officer and co-founder Özlem Türeci said: “Our objective is to further expand the impact of HER2-targeted ADC therapies to chemotherapy naïve patients in metastatic disease stage who express HER2 at low levels at earliest possible treatment lines, seeking to extend the therapeutic window and improve outcomes for these patients.”
