Inclusion Criteria:

          -  Patients with AML who are in morphological remission after allogeneic stem cell
             transplantation with peripheral blood stem cell (PBSC)s or bone marrow if they had at
             least one of the following disease characteristics:

               -  Therapy related AML

               -  Cytogenetics and molecular features consistent with adverse risk group by
                  European LeukemiaNet classification for AML

               -  Primary induction failure defined as absence of complete remission after two
                  different lines of anti-leukemia therapy following diagnosis

               -  Presence of minimal residual disease by multi-color flow cytometry or
                  cytogenetics or molecular studies at the time of HSCT

               -  Presence of active disease defined as bone marrow blast count > 5% at the time of
                  HSCT

               -  Patients transplanted beyond first remission

          -  Patients with biphenotypic or bilineage leukemia (including a myeloid component) or
             mixed phenotype acute leukemia (MPAL) or T cell acute lymphoblastic leukemia who are
             in morphological remission after allogeneic stem cell transplantation with PBSCs or
             bone marrow

          -  The use of reduced intensity regimen with fludarabine/melphalan (100-140 mg/m^2) with
             or without total-body irradiation (TBI) with post-transplant Cytoxan

          -  The use of myeloablative regimens including: sequential busulfan (area under curve
             [AUC] > 5000)/flurabine with post-transplant Cytoxan or TBI/etoposide with any GVHD
             regimen

          -  Patients who are in remission with no detectable minimal residual disease after
             allogeneic stem cell transplant should have:

               -  Adequate engraftment within 14 days prior to starting study drug

               -  Absolute neutrophil count (ANC) >= 1.0 x 10^9/L without daily use of myeloid
                  growth factor

               -  Platelet >= 30 x 10^9/L without platelet transfusion within 1 week; and

               -  Be able to start the drug therapy between 42 to 100 days following HSCT

          -  Persistence or reappearance of minimal residual disease by flow cytometry or
             cytogenetic or molecular testing while being in morphological remission after
             allogeneic stem cell transplantation

          -  Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2

          -  Serum creatinine =< 1.5 mg/dL or creatinine clearance greater or equal than 40 cc/min
             as defined by the Cockcroft-Gault equation

          -  Serum bilirubin =< 1.5 x upper limit of normal (ULN)

          -  Aspartate transaminase (AST) or alanine transaminase (ALT) =< 2.5 x ULN

          -  Alkaline phosphatase =< 2.5 x UL

          -  Capable of understanding the investigational nature, potential risks and benefits of
             the study, and able to provide valid informed consent

          -  Negative serum or urine pregnancy test for women with reproductive potential. The only
             subjects who will be exempt from this criterion are postmenopausal women (defined as
             women who have been amenorrheic for > 12 months) or subjects who have been surgically
             sterilized or otherwise proven sterile

        Exclusion Criteria:

          -  Active acute GVHD grade II or higher

          -  Active chronic GVHD that is extensive

          -  Uncontrolled GVHD

          -  Concurrent use of systemic immune suppressive other than calcineurin inhibitors,
             mycophenolate mofetil (MMF) and sirolimus

          -  Active uncontrolled systemic fungal, bacterial or viral infection

          -  Active bleeding

          -  Symptomatic or uncontrolled arrhythmias

          -  Significant active cardiac disease within the previous 6 months, including: New York
             Heart Association (NYHA) class III or IV congestive heart failure. Unstable angina or
             angina requiring surgical or medical intervention, and/or myocardial infarction

          -  Known active viral infection with human immunodeficiency virus (HIV), hepatitis B
             virus (HBV) or hepatitis C virus (HCV)

          -  Prior history of malignancies, other than leukemia, unless the subject has been free
             of the disease for >= 1 year. However, subjects with the following history/concurrent
             conditions are allowed:

               -  Basal or squamous cell carcinoma of the skin

               -  Carcinoma in situ of the cervix

               -  Carcinoma in situ of the breast

               -  Incidental histologic finding of prostate cancer (T1a or T1b using the tumor,
                  node, metastasis [TNM] clinical staging system)