The purpose of this study is to determine the effectiveness, safety, tolerability and best dose of Lapatinib (GW572016) in combination with carboplatin and paclitaxel.

The MTD was found in the phase I portion of this study to be oral lapatinib 1000 mg per day for each 4 week cycle and paclitaxel 60 mg/m2 weekly x 3 of a 4 week cycle and carboplatin AUC 2 weekly x 3 of a 4 week cycle.

Inclusion Criteria:

• Relapsed (Stage III or IV) ovarian, primary peritoneal, fallopian tube carcinoma patients.
• Stage IV metastatic breast cancer patients who have failed no more than four previous chemotherapies for Stage IV disease.
• Ability to swallow and retain oral medications.
• Measurable disease

Exclusion Criteria:

• Treatment with previous weekly carboplatin and paclitaxel.
• No prior treatment with erbB targeting therapies such as erlotinib, gefitinib and cetuximab.
• No concomitant requirement for medication classification as CYP3A4 inducers or inhibitors.