Inclusion Criteria:

- Acute myeloid leukemia:

- High risk complete response (CR)1 as evidenced by preceding myelodysplastic
syndromes (MDS), high risk cytogenetics (for example, monosomy 5 or 7, or as
defined by referring institution treatment protocol), >= 2 cycles to obtain CR,
erythroblastic or megakaryocytic leukemia; >= CR2

- All patients must be in CR as defined by hematologic recovery and < 5% blasts by
morphology within the bone marrow and a cellularity of >= 15%

- Patients in which adequate marrow/biopsy specimens can not be obtained to
determine remission status by morphologic assessment, but have fulfilled
criteria of remission by flow cytometry, recovery of peripheral blood counts
with no circulating blasts, and/or normal cytogenetics (if applicable) may still
be eligible; reasonable attempts must be made to obtain an adequate specimen for
morphologic assessment, including possible repeat procedures; these patients
must be discussed with the Principal Investigator, Colleen Delaney prior to
enrollment

- Acute lymphoblastic leukemia:

- High risk CR1 [for example, but not limited to: t(9;22), t(1;19), t(4;11) or
other mixed lineage leukemia (MLL) rearrangements, hypodiploid]

- Greater than 1 cycle to obtain CR

- >= CR2

- All patients must be in CR as defined by hematologic recovery and < 5% blasts by
morphology within the bone marrow and a cellularity of >= 15%

- Patients in which adequate marrow/biopsy specimens can not be obtained to
determine remission status by morphologic assessment, but have fulfilled
criteria of remission by flow cytometry, recovery of peripheral blood counts
with no circulating blasts, and/or normal cytogenetics (if applicable) may still
be eligible; reasonable attempts must be made to obtain an adequate specimen for
morphologic assessment, including possible repeat procedures; these patients
must be discussed with the Principal Investigator, Colleen Delaney prior to
enrollment

- Chronic myelogenous leukemia excluding refractory blast crisis; to be eligible in
first chronic phase (CP1) patient must have failed or be intolerant to imatinib
mesylate

- Myelodysplasia International Prognostic Scoring System (IPSS) intermediate 2 (Int-2)
or High risk (i.e., refractory anemia with excess myeloblasts [RAEB], refractory
anemia with excess blasts in transformation [RAEB-T]) or refractory anemia with
severe pancytopenia or high risk cytogenetics; blasts must be < 10% by a
representative bone marrow aspirate morphology

- Karnofsky (>= 16 years old) >= 70%

- Lansky (< 16 years old) >= 50%

- Calculated creatinine clearance must be > 60 mL and serum creatinine =< 2 mg/dL
(adults)

- Calculated creatinine clearance must be > 60 mL/min (children < 18 years old)

- Total serum bilirubin must be < 3mg/dl and transaminases must be < 3 x the upper
limit of normal

- Diffusion capacity of carbon monoxide (DLCO) corrected > 50% normal; for pediatric
patients unable to perform pulmonary function tests, O2 saturation > 92% on room air

- Left ventricular ejection fraction > 45% OR shortening fraction > 26%

- Ability to understand and the willingness to sign a written informed consent document

Exclusion Criteria:

- Uncontrolled viral or bacterial infection at the time of study enrollment

- Active or recent (prior 6 month) invasive fungal infection without infectious disease
(ID) consult and approval

- History of human immunodeficiency virus (HIV) infection

- Pregnant or breastfeeding

- If =< 18 years old, prior myeloablative transplant within the last 6 months

- If > 18 years old prior myeloablative allotransplant or autologous transplant

- Extensive prior therapy including > 12 months alkylator therapy or > 6 months
alkylator therapy with extensive radiation