The US Food and Drug Administration (FDA) has approved Enhertu (trastuzumab deruxtecan), an HER2-targeted antibody drug conjugate (ADC) co-developed by AstraZeneca (AZ, NASDAQ: AZN) and Daiichi Sankyo (TYO: 4568), for the treatment of adult patients with unresectable or metastatic hormone receptor (HR)-positive, HER2-low (IHC 1+ or IHC 2+/ISH-) or HER2-ultralow (IHC 0 with membrane staining) breast cancer. The approval is for patients whose cancer has progressed on one or more endocrine therapies in the metastatic setting, as determined by an FDA-approved test.
Clinical Trial Results Drive Approval
The FDA’s approval was based on results from the Phase III DESTINY-Breast06 study, which enrolled 866 patients from multiple centers across Asia, Europe, North America, Oceania, and South America. In patients with chemotherapy-naïve HER2-low or HER2-ultralow metastatic breast cancer, Enhertu demonstrated a significant reduction in the risk of disease progression or death compared to chemotherapy, with a hazard ratio of 0.64 (p<0.0001). The median progression-free survival (mPFS) for patients treated with Enhertu was 13.2 months, compared to 8.1 months in the chemotherapy group.
Significance of the Approval
This approval marks a significant milestone in the treatment of breast cancer, particularly for patients with HER2-low and HER2-ultralow disease. Enhertu’s demonstrated efficacy in extending progression-free survival underscores its potential as a new standard of care for these patients. The expanded indications further solidify the drug’s position in the oncology treatment landscape.-Fineline Info & Tech
