Inclusion Criteria:

- Patients must have a diagnosis of AML (> 20% myeloid blasts in the peripheral blood
or bone marrow) or MDS with > 10% myeloid blasts in the bone marrow. Patients with
Acute Promyelocytic Leukemia (APL) must be refractory to all-trans retinoic acid
(ATRA) and arsenic trioxide.

- The patients must have one of the following criteria:

- Age of 18 to 69 years; relapsed or refractory disease following at least one
prior therapeutic regimen; not a candidate for cytotoxic or other conventional
therapies due to disease refractoriness, poor performance status, or
co-morbidities

- Age of 70 years or older; received no previous therapies (other than
hematopoietic growth factors or hydroxyurea); not a candidate for cytotoxic or
other conventional therapies due to poor performance status, co-morbidities, or
personal preference

- Age of 70 years or older with relapsed or refractory disease

- The patient must have discontinued all previous therapies for acute leukemia for at
least 14 days and recovered from the acute effects of the therapy.

- Patients must have an ECOG (Zubrod) performance status of 0-2

- Patients must be able to take and tolerate oral medications

- Patients must have adequate organ function as specified in the protocol.

- Patients not on anti-coagulation must have an INR < 1.5 and a PTT within normal
limits.

Exclusion Criteria:

- Pregnant women or nursing mothers are not eligible for this trial.

- Patients may receive no other concurrent biologic therapy, cytotoxic chemotherapy or
radiation therapy during this trial.

- Patients with one or more serious preexisting medical conditions that, in the opinion
of the investigator, would preclude participation in this study. See protocol for
listing.

- Patients with known central nervous system (CNS) leukemia by spinal fluid cytology,
flow cytometry or imaging

- Patients with previous autologous or allogeneic stem cell transplantation who have
current side effects and/or complications that in the opinion of the investigator can
interfere with the interpretation of the toxicities.