Chemotherapy and Lapatinib or Trastuzumab in Treating Women With HER2/Neu-Positive Metastatic Breast Cancer

Subjects were stratified by * Prior (neo) adjuvant HER2/neu targeted therapy (yes, no) * Prior (neo) adjuvant taxane chemotherapy (yes, no) * Planned taxane treatment (once weekly paclitaxel versus docetaxel once every 3 weeks) * Liver metastasis (yes, no) Subjects were randomized 1:1 to the following treatments to a planned sample size of approximately 600 subjects (to achieve 536 centrally confirmed HER2 positive subjects): * Taxane based chemotherapy plus lapatinib for 24 weeks followed by single agent lapatinib * Taxane based chemotherapy plus trastuzumab for 24 weeks followed by single agent trastuzumab The choice of taxane (once weekly paclitaxel versus docetaxel once every 3 weeks) was at the discretion of the treating physician and was specified at the time of subject randomization. A protocol-specified interim analysis was conducted on 27-Apr-2012, following which the participants in the Lapatinib plus taxane based chemotherapy arm could cross over to Taxane based chemotherapy plus Trastuzumab.