Optimizing the first-line treatment of patients with HER2-positive metastatic breast cancer is currently the focus of several clinical trials. One such study, the phase III open-label MA.31 trial, randomized patients to receive taxane-based chemotherapy with lapatinib or trastuzumab.

This trial demonstrated clear results, explains Joyce A. O'Shaughnessy, MD. In all, progression-free survival was inferior in patients treated with lapatinib and a taxane followed by single-agent lapatinib. However, outside of these results, the combination of lapatinib and trastuzumab is of interest, since it provides the opportunity to omit chemotherapy. This treatment approach could be beneficial in patients with asymptomatic disease, O'Shaughnessy believes.

To explore treatment with lapatinib further, a small trial is examining patients with ER-negative, HER2-positive inflammatory breast cancer who experience long remissions. This project is working toward genotyping a niche of patients who benefit more from lapatinib, explains O'Shaughnessy. Further data on lapatinib and trastuzumab in combination and as single-agents will soon be available from the phase III ALTTO trial, the panelists anticipate.