ERBB2 and breast cancer: The pivotal phase III EMELIA trial which led to FDA approval of T-DM1 in 2013 showed an improved mPFS of 9.6 months with T-DM1 vs. 6 months with lapatinib plus capecitabine (HR 0.65, 95% CI 0.55–0.77; p < 0.001) and median overall survival (mOS) of 30.9 vs. 25.1 months (HR 0.68, 95% CI 0.55–0.85; p < 0.001) in patients with ErbB2-positive advanced breast cancer previously treated with trastuzumab and a taxane [29,54].