AstraZeneca’s HER2-targeting antibody drug conjugate (ADC), DS-8201 (trastuzumab deruxtecan), demonstrated a clinically meaningful response in patients with refractory HER2-positive metastatic breast cancer.

The company and Daiichi Sankyo announced positive top-line results for the pivotal Phase II DESTINY-Breast01 trial, which evaluated the treatment in patients with HER2-positive, unresectable and metastatic breast cancer previously treated with trastuzumab emtansine.

DESTINY-Breast01 is a pivotal Phase II, open-label, global, multicentre, two-part trial of the ADC, which found that the safety and tolerability profile was also consistent with previous experience.

The news is welcome as the indication is an area of high unmet need, with approximately one in five breast cancers being HER2-positive. Many HER2-positive breast cancers eventually advance to the point where no currently-approved HER2-targeting medicine continues to control the disease; after treatment with trastuzumab, pertuzumab, and trastuzumab emtansine, optimal treatment is less-clearly defined and choices may be limited.

José Baselga, executive vice president of R&D Oncology at Astra Zeneca, said that the company are “encouraged to see positive data, with the DESTINY-Breast01 trial now reinforcing what earlier data have shown”, and that “We believe this antibody drug conjugate has the potential to redefine the treatment of patients with HER2-expressing cancers, and we are eager to bring it as quickly as possible to patients with refractory HER2-positive breast cancer who continue to have high unmet medical need.”

The drug has been granted US FDA Breakthrough Therapy Designation and Fast Track Designation for HER2-positive patients in the advanced or refractory breast cancer setting.