FX.co ★ AstraZeneca: Enhertu Improved PFS In HR-positive, HER2-low Metastatic Breast Cancer

British pharmaceutical giant AstraZeneca announced important new results from its DESTINY-Breast06 Phase III trial on Monday. The trial found that Enhertu (trastuzumab deruxtecan), a drug developed jointly by AstraZeneca and Daiichi Sankyo, demonstrated a significant and clinically meaningful improvement in progression-free survival (PFS) in HR-positive, HER2-low metastatic breast cancer patients who have previously undergone one or more rounds of endocrine therapy.

Enhertu, a carefully engineered DXd antibody drug conjugate (ADC) targeting HER2, has shown highly positive outcomes in terms of enhancing PFS when tested against standard-of-care chemotherapy in the primary patient population of the trial.

This benefit was also seen in patients exhibiting HER2-ultralow expression, showing consistency in clinical improvement between the HER2-low and HER2-ultralow groups, according to a pre-specified subgroup analysis.

Though the full overall survival (OS) data were still incomplete at the time of this analysis, early trends show that Enhertu might lead to improvements in OS compared to standard-of-care chemotherapy in HER2-low metastatic breast cancer patients and the entire trial population.

Moving forward, the trial will continue as originally planned to evaluate OS and other secondary endpoints further. Susan Galbraith, Executive Vice President of Oncology R&D at AstraZeneca, expressed optimism that Enhertu could become a new standard of care for patients with HER2-low and HER2-ultralow metastatic breast cancer who have undergone one or more lines of endocrine therapy.

Galbraith asserts that these results underline the potential of Enhertu in treating a broad range of HR-positive breast cancers, possibly redefining the treatment approach towards metastatic breast cancer.

The data from this exciting trial will be presented at an upcoming medical meeting and shared with global regulatory authorities in due time.