ERBB2 and breast cancer: However, recent data have demonstrated that some of the HER2 directed antibody–drug conjugates (ADC) such as trastuzumab–emtansine (T‐DM1) and trastuzumab–deruxtecan (T‐DXD) can improve the outcome of patients with BC that express HER2 protein without evidence of HER2 gene amplification.10