Inclusion Criteria:

- KPS performance status of >= 80% ("normal activity with effort")

- Metastatic breast cancer with Her2 amplification by FISH or 3+ Her2 overexpression by
immunohistochemistry ("IHC")

- Must have received no more than one prior cytotoxic chemotherapy regimen in the
metastatic setting

- Measurable disease by RECIST Criteria

Exclusion Criteria:

- Received prior lapatinib, an investigational ErbB-2 and/or an investigational EGFR
dual tyrosine kinase inhibitors

- Administration of any other chemotherapy, biological, immunotherapy or
investigational agent within 14 days prior to receipt of study medication

- Pregnant or breast-feeding women. Known CNS metastases, unless treated and without
clinically significant neurological deficits

- Moderately severe dry eye

- Congestive heart failure, or a left ventricular ejection fraction

- Myocardial infarction or active ischemic heart disease within 12 months prior to
study drug administration

- Previous malignancies unless free of recurrence for at least 5 years