Already approved for HER2-low metastatic breast cancer (MBC) after at least one line of chemotherapy, the antibody–drug conjugate trastuzumab deruxtecan (T-DxD) (Enhertu, Daiichi Sankyo/AstraZeneca) appears to be emerging as a standard in MBC with low or ultralow HER2 expression following hormone therapy alone, according to results of a multicenter randomized trial.
The fact that T-DxD proved to be highly active in MBC, even with very low HER2 expression, “represents a potential