Abstract
Improved molecular understanding of breast cancer in recent years has led to the discovery of important drug targets such as HER-2 and EGFR. Lapatinib is a potent dual inhibitor of HER-2 and EGFR. Preclinical and phase I studies have shown activity with lapatinib in a number of cancers, including breast cancer, and the drug is well tolerated. The main known drug interactions are with paclitaxel and irinotecan. The most significant side-effects of lapatinib are diarrhea and adverse skin events. Rates of cardiotoxicity compare favorably with trastuzumab, a monoclonal antibody against HER-2. This paper focuses on lapatinib in advanced and metastatic breast cancer, which remains an important therapeutic challenge. Phase II and III studies show activity as monotherapy, and in combination with chemotherapy or hormonal agents. Results from these studies suggest that the main benefit from lapatinib is in the HER-2 positive breast cancer population. Combinations of lapatinib and trastuzumab are also being studied and show encouraging results, particularly in trastuzumab-refractory metastatic breast cancer. Lapatinib may have a specific role in treating HER-2 positive CNS metastases. The role of lapatinib as neoadjuvant therapy and in early breast cancer is also being evaluated.