Positive topline results from a Phase III trial for Daiichi Sankyo and AstraZeneca’s breast cancer drug Enhertu have shown that the HER2-directed antibody drug conjugate (ADC) ADC demonstrated superiority over trastuzumab emtansine (T-DM1).

The Independent Data Monitoring Committee (IDMC) concluded that DESTINY-Breast03 trial met the primary endpoint of progression-free survival (PFS), showing a highly statistically significant and clinically meaningful improvement in PFS for patients with HER2 positive unresectable and/or metastatic breast cancer previously treated with trastuzumab and a taxane.

Enhertu also showed a ‘strong trend’ toward improved overall survival (OS) compared to T-DM1 in a key secondary endpoint, although the OS data are still immature.

Ken Takeshita, global head, research and development, Daiichi Sankyo, said: “We believe this specifically engineered ADC, with a highly sophisticated delivery system, is fulfilling its promise to reshape the treatment of HER2 positive metastatic breast cancer with the goal to move into earlier lines of treatment for HER2 positive breast cancer, as well as many other HER2 expressing tumour types across our broad clinical trial programme.”

Susan Galbraith, executive vice president, oncology R&D, AstraZeneca, added: “These transformative progression-free survival results demonstrate the superiority of Enhertu compared to T-DM1 and the encouraging safety data may open future opportunities to bring this benefit to patients in earlier treatment settings.”