Targeted Therapies in HER2-Overexpressing Metastatic Breast Cancer

Human epidermal growth factor receptor-2 (HER2) is amplified in 25-30% of breast cancers and is associated with aggressive disease and poorer survival. Multiple anti-HER2 targeted therapies have dramatically changed management and outcome of this subgroup, both in adjuvant and metastatic settings. Despite the improvement of survival thanks to trastuzumab, unclear mechanisms of resistance occur, which has led to the development of new anti-HER2 therapies such as lapatinib, pertuzumab, and trastuzumab emtansine (T-DM1). The optimal sequence of the available drugs is still not well established. All this progress raises the question of toxicity that need to be managed, especially with longer survival of patients. In this article, we review different anti-HER2 therapies used in HER2-positive m etastatic breast cancer.