Advances in the management of HER2-positive early breast cancer.

While trastuzumab is firmly established as the cornerstone of therapy for both early and advanced breast cancer expressing human epidermal growth factor receptor 2 (HER2), many patients either do not respond to trastuzumab treatment or progress following therapy. Improved understanding of breast cancer biology, particularly the complex signaling interactions managed by the HER family of receptors, have resulted in development of several novel HER2-directed therapies and combinations. This article will review the novel approaches to HER2 targeting that have been developed in recent years, with particular focus on results from these approaches in early breast cancer, and will discuss strategies to improve the tolerability of HER2-directed therapies, including prevention of cardiac toxicity and diarrhea.