Ado-trastuzumab emtansine (Kadcyla@), approved in 2013, consists of a stable thioether linker (SMCC) attached to trastuzumab (anti-human epidermal growth factor receptor-2 antibody, anti-HER2 antibody) and DM1 (maytansine derivative) for the treatment of advanced breast cancer (Lambert and Chari, 2014). Here, ERBB2 is linked to breast cancer.