This new nomenclature has been proposed due to the subset of HER2‐low breast cancer patients who have benefited from the novel antibody–drug conjugates (ADCs), namely trastuzumab deruxtecan (T‐DXd) which was shown to be effective for HER2‐low metastatic breast cancer in the phase 3 DESTINY‐Breast04 trial.22 This evidence concerns the gene ERBB2 and breast cancer.