Adjuvant paclitaxel with trastuzumab is a common combination treatment for invasive early breast cancers with overexpression of HER2. In a phase II clinical trial, Sara M. Tolaney, MD, MPH, and colleagues from the Dana-Farber Cancer Institute, Boston, reported that 1 year of adjuvant therapy with trastuzumab emtansine (T-DM1) resulted in “excellent” invasive disease–free survival compared with paclitaxel plus trastuzumab but not a real difference in clinically relevant toxicities. Their results were reported in the Journal of Clinical Oncology.