Oral Drug Study In Women With Refractory Metastatic Breast Cancer After First-line or Second-line Herceptin.

Inclusion Criteria: (The patient must meet the following criteria in order to be eligible for this study.) * Signed informed consent * No more than two prior regimens for metastatic breast cancer. Each regimen must have contained Herceptin. * Refractory Stage IIIb or IV breast cancer * HER2/neu tumor overexpression * Disease progression while receiving a prior chemotherapy regimen with Herceptin alone or in combination with other chemotherapy. * Tumor tissue available for testing. * 2 weeks since treatment with Herceptin (alone or in combination). * Able to swallow and retain oral medication * Cardiac ejection fraction within the institutional range of normal as measured by MUGA (Multiple Gated Acquisition Scan). * Adequate kidney and liver function * Adequate bone marrow function Exclusion Criteria: (The patient cannot meet any of the following criteria in order to be eligible for this study.) * Prior regimens did not include Herceptin. * Pregnant or lactating. * Conditions that would affect absorption of an oral drug * Serious medical or psychiatric disorder that would interfere with the patient's safety or informed consent. * Severe cardiovascular disease or cardiac disease requiring a device. * Active infection. * Brain metastases. * Concurrent cancer therapy or investigational therapy. * Use of oral or IV steroids. * Unresolved or unstable serious toxicity from prior therapy. * Treatment with EGFR (Endothelial Growth Factor Receptor) inhibitor other than Herceptin.