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Editor’s note: The orally bioavailable tyrosine kinase inhibitor of HER1 (EGFR) and HER2, lapatinib, is now licensed for use in patients whose metastatic disease has progressed despite trastuzumab therapy. As well as being orally bioavailable, one of the potential benefits of this agent is its inhibition of HER1, although the extent to which breast cancer expresses this growth factor receptor remains a matter of debate. Testing the agent in an unselected group provides the opportunity to test the hypothesis that HER1 inhibition may be relevant. This study was largely conducted in South America and Eastern Europe, where trastuzumab is not widely available. Patients unselected for HER2 expression entered the study, which compared paclitaxel (175 mg/m
2) and lapatinib with paclitaxel and placebo. A pre-planned retrospective evaluation of HER2 expression was performed using immunohistochemistry and fluorescence
in situ hybridization.