New data presented at the 2021 European Society for Medical Oncology (ESMO) congress showed AstraZeneca and Daiichi Sankyo’s Enhertu (trastuzumab deruxtecan) can reduce disease progression or death in women with HER2-positive metastatic breast cancer.

An interim analysis of the DESTINY-Breast03 trial found Enhertu led to a 72% reduction in the risk of disease progression or death compared to trastuzumab emtansine (T-DM1), a HER2-directed antibody drug conjugate (ADC) currently approved to treat patients with HER2-positive unresectable and/or metastatic breast cancer previously treated with trastuzumab and a taxane.

Following 15.5 and 13.9 months of follow-up in the Enhertu and T-DM1 arms respectively, the median progression-free survival had not been reached for patients treated with Enhertu compared ti 6.8 months for T-DM1.

Although there was a ‘strong trend’ towards improved overall survival (OS) with Enhertu, this analysis is no t yet mature and is not statistically significant.

The confirmed objective response rate (ORR) more than doubled in the Enhertu arm versus the T-DM1 arm, with 16.1% complete responses (CR) and 63.6% partial responses (PR) observed in patients treated with Enhertu compared to 8.7% CRs and 25.5% PRs in patients treated with T-DM1.

“Today’s results are ground-breaking. Enhertu tripled progression-free survival as assessed by investigators, and provided a disease control rate exceeding 95% compared to 77% for T-DM1 in DESTINY-Breast03. In addition, the safety profile was encouraging with no Grade 4 or 5 interstitial lung disease events in this trial,” said Susan Galbraith, executive vice president, oncology R&D, AZ.

“These unprecedented data represent a potential paradigm shift in the treatment of HER2-positive metastatic breast cancer, and illustrate the potential for Enhertu to transform more patient lives in earlier treatment settings,” she added.