Required initial laboratory tests: Blood urea nitrogen (BUN) and Creatinine values must be less than or equal to 1.5 times the normal values; alternatively, patients with creatinine clearance of greater than 50 ml per minute will also be eligible. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) values must be less than or equal to 2.0 times normal values; patients with laboratory values greater than these levels may be enrolled on the protocol (after a specific approval from the Principal Investigator) if the values are due to a known, pre-existing liver disease. Bilirubin must be less than or equal to 2.0 mg/dl unless due to Gilbert's disease.