About 15%-20% of breast cancer patients show human epidermal growth factor receptor 2 (HER2) positive overexpression with a higher invasiveness.191,192 Ado-trastuzumab emtansine, also known as T-DM1, is an ADC drug targeting HER2 and the first ADC to be approved in a solid tumor. Here, ERBB2 is linked to breast carcinoma.