Lonafarnib in Metastatic Breast Cancer

OUTLINE: This is a multi-center study Patients will be treated with lonafarnib 200 mg PO BID daily on days 1-21 of every 21-day cycle until progression of disease, unacceptable toxicity, or investigator's discretion. 1 Cycle = 21 days of lonafarnib (plus the time required to recover from toxicity if encountered). ECOG Performance Status 0-1 Life Expectancy: Not Specified Hematopoietic: * Platelets \> 100 K/mm3 * Absolute Neutrophil Count (ANC) \> 1.2 K/mm3 * Hemoglobin ≥ 9 g/dl * Serum potassium ≥ 3.3 mmol/L Hepatic: * Aspartate transaminase (AST) ≤ 5.0 x ULN * Alanine transaminase (ALT) ≤ 5.0 x ULN * Total bilirubin \< 1.5 x ULN Renal: * Calculated creatinine clearance (using Cockcroft-Gault formula) \> 45 cc/min Cardiovascular: * No history of Torsades de Pointes, ventricular tachycardia, ventricular fibrillation or ventricular flutter