An Open-Label, Multicenter, Single Arm Phase II Study of Oral GW572016 as Single Agent Therapy in Subjects With Advanced or Metastatic Breast Cancer Who Have Progressed While Receiving Herceptin† Containing Regimens

Inclusion Criteria

Inclusion criteria:

- 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) or Echocardiogram.

- Adequate kidney and liver function

- Adequate bone marrow function

Exclusion criteria:

- 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 and/or Her2-neu inhibitor other than Herceptin.