Study of Foretinib in Combination With Lapatinib in Patients With Metastatic Breast Cancer

The purpose of this study is to find the dose of foretinib that can safely be given in combination with lapatinib. This is done by starting at doses of both drugs lower than the usual doses of each when given on their own. Patients are given foretinib and lapatinib and are watched very closely to see what side effects they have and to make sure the side effects are not severe. If the side effects are not severe, then more patients are asked to join the study and are given higher does of foretinib and lapatinib. Patients joining the study later on will get higher doses of foretinib and lapatinib than patients who join earlier. This will continue until a dose is found that causes severe but temporary side effects. Doses higher than that will not be given.