Targeting alternative pathways in HER2-positive breast cancer.

Trastuzumab (Herceptin) has dramatically changed the treatment of human epidermal growth factor receptor 2 (HER2)-positive breast cancer. A phase III trial of firstline trastuzumab with various chemotherapy regimens compared with chemotherapy alone demonstrated a significant improvement in survival (25.1 vs 20.3 months) and overall response (50% vs 32%).1 This study resulted in the approval of trastuzumab with paclitaxel for first-line treatment of HER2-postive metastatic breast cancer. Four large trials have demonstrated an improvement in outcomes with the incorporation of 1 year of trastuzumab into standard adjuvant chemotherapy regimens.2-6