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

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