GW572016 and Trastuzumab in Treating Patients With Metastatic Breast Cancer That Overexpresses HER2/Neu

OBJECTIVES: Primary * Determine the optimally tolerated regimen of GW572016 when administered with trastuzumab (Herceptin\^®) in patients with metastatic breast cancer that overexpresses HER2/neu. * Determine the safety and tolerability of this regimen in these patients. Secondary * Determine the pharmacokinetic parameters of this regimen in these patients. * Determine the clinical response in patients treated with this regimen. OUTLINE: This is an open-label, multicenter, dose-escalation study of GW572016. Patients receive oral GW572016 once daily on days 1-28 and trastuzumab (Herceptin\^®) IV over 90 minutes on days 1, 8, 15, and 22. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. Cohorts of 3-6 patients receive escalating doses of GW572016 until the optimally tolerated regimen (OTR) is determined. The OTR is defined as the dose preceding that at which 2 of 6 patients experience dose-limiting toxicity. Once the OTR is determined, 10-18 additional patients are entered and treated at the OTR. Patients are followed at 28 days. PROJECTED ACCRUAL: A total of 3-35 patients will be accrued for this study.