Inclusion Criteria:

- Body surface area >= 1 m^2

- Allogeneic HCT

- Acute lymphocytic leukemia (ALL) or chronic myelogenous leukemia (CML) characterized
by the p190 and/or p210 BCR/ABL gene rearrangement

- CML in accelerated phase, blast crisis, or blast crisis remission as defined by World
Health Organization (WHO) criteria

- CML in chronic phase if patient age =< 17 years or a patient of any age with CML in
second chronic phase or beyond

- Patients with minimal residual disease (MRD) that is not declining in response to
tyrosine kinase inhibitor therapy must be screened for the T315I and other mutations

- An appropriately matched related or unrelated donor

- Signed informed consent

- Patient must have a life expectancy of at least 2 months

- Stated willingness of the patient to comply with study procedures and reporting
requirements

- Creatinine =< 2.0 x upper limit normal (ULN)

- Platelets > 20 x 10^9 /L

- Serum aspartate aminotransferase (AST)/alanine aminotransferase (ALT) =< 3 x ULN,
conjugated bilirubin < 3 x ULN

- Serum potassium phosphorus, magnesium, and calcium >= lower limit normal (LLN) or
correctable with supplements prior to first dose of study drug; calcium levels may be
corrected for hypoalbuminemia

- Serum amylase and lipase < 1.5 x ULN

- Female patients of childbearing potential must have negative pregnancy test within 7
days before initiation of study drug dosing; postmenopausal women must be amenorrheic
for at least 12 months to be considered of non-childbearing potential; male and
female patients of reproductive potential must agree to employ an effective barrier
method of birth control throughout the study and for up to 3 months following
discontinuation of study drug

- Careful rationalization with a view to discontinuing or considering alternatives to
any concomitant medications that have potential to prolong the QT interval

Exclusion Criteria:

- Autologous transplant

- Non-myeloablative transplant

- Patient age > 17 years with CML in first chronic phase

- Aberrant antigen expression on marrow leukemic blasts >= 5% by multidimensional flow
cytometric assay immediately before conditioning (CML patients in chronic phase
exempt from flow cytometry screening)

- Ph+ ALL without complete cytogenetic remission immediately before conditioning

- Known T315I mutation

- Hypersensitivity to Gleevec or Tasigna

- Patients who are Tasigna-resistant or intolerant

- Central nervous system (CNS) involvement with leukemia at baseline (pre-imatinib
therapy); CML chronic phase (CP), accelerated phase (AP) patients exempt from CNS
involvement screening

- Female patients who are pregnant, breast-feeding, or of childbearing potential
without a negative serum pregnancy test at screening; male or female patients of
childbearing potential unwilling to use effective contraceptive precautions
throughout the trial; post-menopausal women must be amenorrheic for at least 12
months to be considered of non-childbearing potential

- Life expectancy severely limited by diseases other than leukemia

- Myocardial infarction within one year prior to starting nilotinib

- Other clinically significant heart disease (e.g. congestive heart failure,
uncontrolled hypertension, unstable angina)

- Absolute neutrophil count (ANC) less than 1500 per microliter at study entry despite
the use of filgrastim (G-CSF)

- Impaired cardiac function, including any one of the following:

- Complete left bundle branch block or bifascicular block (right bundle branch
block plus left anterior hemiblock) or use of ventricular-paced pacemaker

- Congenital long QT syndrome or a family history of long QT syndrome

- History of or presence of significant ventricular or atrial tachyarrhythmias

- Clinically significant resting bradycardia (< 50 beats per minute)

- QTc > 450 milliseconds on screening electrocardiogram (ECG); if QTc > 450 and
electrolytes are not within normal ranges, electrolytes should be corrected and then
the patient rescreened for QTc