Inclusion Criteria

DISEASE CHARACTERISTICS:

- Newly diagnosed acute lymphoblastic leukemia

- Must be assigned to receive prednisone/prednisolone, vincristine, and daunorubicin
during induction treatment in the doses and schedule as per the current COG AALL0232
protocol

- Prior registration onto a COG protocol is not required

- Must meet 1 of the following criteria:

- Obese (defined as a body mass index [BMI] ≥ 95^th percentile)

- Normal weight or at risk for overweight (defined as BMI between 10^th and 95^th
percentile)

- Underweight (defined as ≤ 10^th percentile)

PATIENT CHARACTERISTICS:

- Able to take either prednisone or prednisolone by mouth on day 1 or 8 of induction
therapy

- Not pregnant

- Negative pregnancy test

- AST/ALT < 5 times upper limit of normal (ULN)

- Total bilirubin (conjugated + unconjugated) < 1.5 mg/dL

- Creatinine ≤ 1.5 times ULN

- No known malabsorption syndrome

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

- At least 2 weeks since prior and no concurrent medications or food known or with the
potential to alter the pharmacokinetics of the drugs under study including any of the
following

- Grapefruit, tangelos, or the juice of these fruits

- Hypericum perforatum (St. John's wort)

- Anticonvulsants

- Carbamazepine

- Oxcarbazepine

- Phenytoin

- Phenobarbital

- Primidone

- Azole antifungal agents including:

- Ketoconazole

- Fluconazole

- Itraconazole

- Voriconazole

- Macrolide antibiotics

- Erythromycin

- Clarithromycin

- Isoniazid

- Rifampin

- Verapamil

- Diltiazem