Letrozole and Lapatinib Followed by Everolimus in Women With Advanced Breast Cancer

This is a single-institution clinical trial. Patients will be stratified according to the HER2 status: Group 1: HER2-positive in the tumor tissue Group 2: HER2 negative in the tumor tissue In the first part of the study, all of the patients will receive the combination of lapatinib 1,500 mg/day and letrozole 2.5 mg/day. We do not expect any significant toxicity from this combination since the previous study of lapatinib and letrozole showed that this combination is safe with no grade 3-4 toxicities observed. Restaging scans (CT scan, MRI, or bone scan) will be obtained after every 12 weeks of treatment. In those patients who progress from any group, everolimus 5 mg/day will be added to letrozole and lapatinib will be reduced to 1,250 mg/day as per the SWOG phase I study of lapatinib and everolimus. The outcome of each group will continue to be assessed separately. We do not expect to see additional serious toxicity from adding everolimus to the combination of lapatinib and letrozole. All of the treatment will be continued until disease progression.