Inclusion Criteria:

- Patients must be ≥1 and ≤ 21 years of age when originally diagnosed with ALL or AML.

- Diagnosis

1. Patients must have previously histologically confirmed ALL or AML at original
diagnosis or previous relapse.

2. Patients must be in complete remission (CR) with less than 5% blasts in the bone
marrow.

- Post-HSCT patients should be in first or greater CR

- Patients who have never received HSCT should be in second or greater CR c. Patient
must have detectable MRD (≥0.01%) by flow cytometry as confirmed by Brent Woods' lab.
Results must be available at the time of enrollment.

- Karnofsky ≥ 50% for patients >16 years of age and Lansky ≥ 50% for patients ≤16
years of age. (See Appendix I for Performance Scales)

- Patients must have fully recovered from the acute toxic effects of all prior
anti-cancer therapy.

- At least 14 days must have elapsed since any treatment with systemic chemotherapy
including high-dose steroid (prednisone>0.5 mg/kg or equivalent), radiotherapy,
biological therapy or any other investigational therapy. (Note: low-dose steroid;
prednisone ≤0.5 mg/kg/day or equivalent is allowed.)

- Patients who have never had a Hematopoietic Stem Cell Transplant (HSCT) must not be a
suitable candidate for HSCT.

- Previous Hematopoietic Stem Cell Transplant:

1. Patients having received HSCT are eligible.

2. Patients having received donor lymphocyte infusions (DLI) are eligible.

3. At least 60 days must have elapsed from the last DLI.

4. Must have ≥95% donor T-cell chimerism.

5. Patients must have been off all immune suppression drugs for 7 days before study
entry. (at least 2 weeks for high-dose steroid, i.e. prednisone>0.5 mg/kg or
equivalent; see section 3.3.4 b) (Note; low-dose steroid; prednisone ≤0.5
mg/kg/day or equivalent is allowed.)

- Patients must have a serum creatinine that is less than or equal to 1.5 x the
institutional upper limit of normal according to age.

- Patient's alanine aminotransferase (ALT) and aspartate aminotransferase (AST) must be
less than or equal to 3 x institutional upper limit of normal.

- Patient's total bilirubin must be less than or equal to 1.5 x institutional upper
limit of normal.

- Patient must have a shortening fraction > 27% or an ejection fraction > 45% by
echocardiogram (ECHO) or multigated radionuclide angiography (MUGA) .

- Female patients of childbearing potential must have a negative urine or serum
pregnancy test confirmed prior to enrollment.

- Female patients with infants must agree not to breastfeed their infants while on this
study.

- Male and female patients of child-bearing potential must agree to use an effective
method of contraception approved by the investigator during the study.

- Patients must have an absolute neutrophil count > 1000/dL, platelets > 100,000/dL AND
absolute lymphocyte count > 200 which is not decreasing. Patients with previous HSCT
may have a platelet count > 50,000/dL.

Exclusion Criteria:

- Active grade 2 or higher acute GVHD at the time of study entry.

- Active chronic GVHD (moderate or severe). See Appendix 2 for Chronic GVHD Grading.

- Plan for donor lymphocyte infusions during the study period.

- Need for immunosuppressive medications including high-dose corticosteroids
(prednisone >0.5 mg/kg or equivalent) (Note: low-dose steroid; prednisone ≤0.5
mg/kg/day or equivalent is allowed.)

- Patients with a systemic fungal, bacterial, viral, or other infection not controlled
(defined as exhibiting ongoing signs/symptoms related to the infection and without
improvement, despite appropriate antibiotics or other treatment).

- Patient will be excluded if they are currently receiving other investigational drugs.

- Patients will be excluded if there is a plan to administer non-protocol chemotherapy,
radiation therapy, or immunotherapy during the study period.

- Patients will be excluded if they have significant concurrent disease, illness,
psychiatric disorder or social issue that would compromise patient safety or
compliance with the prescribed protocol therapy, interfere with consent, study
participation, follow up, or interpretation of study results.

- Patients with central nervous system 3 disease are excluded.