Inclusion Criteria:

- patients scheduled to undergo non-myeloablative allogeneic stem-cell transplantation.

- meet institutional eligibility criteria for allogeneic SCT. Significant criteria are:

- Renal function: Serum creatinine <2; or calculated creatinine clearance > 40
mL/min/1.72m2;

- Hepatic function: Baseline direct bilirubin, ALT or AST lower than three times
the upper limit of normal;

- Pulmonary disease: FVC or FEV1 > 40% predicted; Cardiac ejection fraction > 40%.

Exclusion Criteria:

- Patients not expected to be available for follow-up in our institution for at least
100 days after the transplant

- Patients who aren ot undergoing standard non-myeloablative SCT with Flu/Bu
conditioning and Tax/MTX GVHD prophylaxis

- Patients with uncontrolled bacterial, viral or fungal infections

- Patients who take strong inducers or inhibitors of the CYP450A4

- Patients receiving other investigational drugs for GVHD

- Women who are pregnant, plan to become pregnant or are breastfeeding