In this study the investigators plan to develop a method to determine optimal busulfan dose through pharmacokinetic study.

Busulfan is a highly toxic drug with narrow therapeutic window used for the conditioning of hematopoietic stem cell transplantation. High exposure is associated with systemic toxicity such as veno-occlusive disease (VOD) and underexposure is associated with graft failure or relapse. In this study we plan to develop a method to determine optimal busulfan dose through pharmacokinetic study.

Inclusion Criteria:

1. Hematopoietic stem cell transplantation with busulfan based conditioning
2. Age: no limits.
3. Performance status: ECOG 0-2.
4. Patients must be free of significant functional deficits in major organs, but the following eligibility criteria may be modified in individual cases. 1. Heart: a shortening fraction > 30% and ejection fraction > 45%. 2. Liver: total bilirubin < 2 × upper limit of normal; ALT < 3 × upper limit of normal. 3. Kidney: creatinine <2 × normal or a creatinine clearance (GFR) > 60 ml/min/1.73m2.
5. Patients must lack any active viral infections or active fungal infection.
6. Appropriate donor is available: Matched in 6/6 of A, B, DR loci.
7. Patients (or one of parents if patients age < 19) should sign informed consent.

Exclusion Criteria:

1. Pregnant or nursing women.
2. Malignant or nonmalignant illness that is uncontrolled or whose control may be jeopardized by complications of study therapy.
3. Psychiatric disorder that would preclude compliance.