Lapatinib plus letrozole for postmenopausal patients with advanced HER2(+)/HR(+) breast cancer.

Lapatinib is an oral, small-molecule dual inhibitor of human EGF receptor 1 (EGFR/erbB1) and 2 (HER2/erbB2). Lapatinib has recently been approved, in combination with capecitabine, for the treatment of HER2-positive metastatic breast cancer patients failing trastuzumab therapy. Data from clinical trials are consistently showing the key role of this agent in the management of HER2-positive disease. Moreover, interesting data are suggesting a key role of lapatinib in enhancing endocrine responsiveness and/or restoring endocrine sensitivity in hormone receptor-positive disease. The present article will summarize the main data leading to the clinical development of the combination of lapatinib and the aromatase inhibitor letrozole.