ERBB2 and breast cancer: In the EMILIA study,9 T-DM1 demonstrated superior efficacy overlapatinib plus capecitabine in patients with HER2-positive advanced breast cancer previously treated with trastuzumab and taxanes, significantly prolonging both PFS (9.6 months vs 6.4 months) and OS (30.9 months vs 25.1 months) while also achieving a higher ORR (43.6% vs 30.8%) with a more favorable toxicity profile.