STEP I: Bilirubin =< 1.5 mg/dL (obtained within 28 days prior to randomization) STEP II: Any adverse event related to step 1 therapy must have resolved to grade 2 or less STEP II: Hemoglobin >= 8 g/dL (within 28 days prior to randomization to Step II) STEP II: Platelet count >= 75,000 cells/mm^3 (within 28 days prior to randomization to Step II) STEP II: Absolute neutrophil count >= 1000 cells/mm^3 (within 28 days prior to randomization to Step II) STEP II: Calculated creatinine clearance >= 30 mL/min (within 28 days prior to randomization to Step II) STEP II: Bilirubin =< 1.5 mg/dL (within 28 days prior to randomization to Step II) STEP II: SGPT (ALT) and SGOT (AST) < 2.5 times the upper limit of normal (within 28 days prior to randomization to Step II) STEP 2: RANDOMIZATION RANDOMIZATION (STEP 1) PRIOR TO STEP ONE RANDOMIZATION: PRIOR TO STEP TWO RANDOMIZATION: