ERBB2 and breast cancer: To illustrate, results of a single-arm phase 2 trial support treatment of patients with early-stage node-negative HER2pos BC with only a single chemotherapy agent (ie, paclitaxel) combined with trastuzumab.14 Furthermore, the HER2-targeted antibody-drug conjugate trastuzumab emtansine (T-DM1) has demonstrated effective in incomplete responders to trastuzumab/pertuzumab/neoadjuvant chemotherapy and in patients with metastatic HER2pos BC.