AstraZeneca reports updated results from DESTINY-Breast03 Phase 3 trial

Updated results from the DESTINY-Breast03 Phase III trial showed that Enhertu demonstrated a "statistically significant and clinically meaningful" improvement in overall survival, or OS, compared to trastuzumab emtansine in patients with HER2-positive unresectable and/or metastatic breast cancer previously treated with trastuzumab and a taxane, AstraZeneca reported. These results and primary results from the DESTINY-Breast02 Phase III trial will be presented today at the 2022 San Antonio Breast Cancer Symposium, or SABCS, with the updated results from DESTINY-Breast03 simultaneously published in The Lancet. Enhertu is a specifically engineered HER2-directed antibody drug conjugate being jointly developed and commercialized by AstraZeneca and Daiichi Sankyo. In the key secondary endpoint analysis of OS for DESTINY-Breast03, Enhertu demonstrated a 36% reduction in risk of death versus T-DM1. In both treatment arms, median OS was not yet reached after a median duration of follow-up of 28.4 months for Enhertu and 26.5 months for T-DM1. An estimated 77.4% of patients were alive in the Enhertu arm at two years compared to 69.9% of patients treated with T-DM1. The observed survival benefit was consistent across all analyzed subgroups, including patients with or without baseline brain metastases, with or without baseline visceral disease, those who were hormone receptor (HR)-positive or HR-negative, and regardless of prior pertuzumab or lines of systemic therapy.