Ado-trastuzumab emtansine (T-DM1), which contains a monoclonal antibody targeting human epidermal growth factor receptor 2 (HER2) linked to a payload of microtubule inhibitor DM1 through a non-cleavable thioether linker, was approved for the treatment of HER2-positive breast cancer in 2013 (Boyraz et al., 2013). Here, ERBB2 is linked to breast cancer.