Trastuzumab emtansine (T-DM1) has shown improved OS in HER2-positive early breast cancer patients with residual invasive disease after neoadjuvant therapy; in the KATHERINE trial, 7-year OS was 89.1% with T-DM1 versus 84.4% with trastuzumab [32]. The gene discussed is ERBB2; the disease is breast carcinoma.