Inclusion Criteria:

- Patients must have a diagnosis of one of the following:

- relapsed or refractory AML or ALL that has failed to respond to standard
therapy, has progressed despite standard therapy

- relapsed or refractory Myelodysplastic Syndromes

- previously untreated AML or Myelodysplastic Syndromes in patients > 60 years of
age who refused or are not candidates for induction chemotherapy

- Patients with relapsed or refractory CML that has failed to respond to Imatinib
therapy or standard therapy, has progressed despite standard therapy, or for which
no standard therapy exists

- ECOG performance status of 0, 1, or 2

- Age ≥ 18 years

- Patients or their legal representative must be able to read, understand, and sign a
written informed consent (approved by the IRB/EC) prior to study entry

Exclusion Criteria:

- Patients with a history of another cancer other than basal cell carcinoma or cervical
intraepithelial neoplasia

- Pregnant or lactating women

- Patients and their partners, if either are of childbearing potential, not using
adequate birth control measures throughout the study and for 90 days following the
last dose of study medication

- Patients with known meningeal metastasis(es)

- Patients with active or uncontrolled infections, or with a fever >38.5 C

- Patients with serious illnesses, medical conditions, or other medical history, which
would be likely to interfere with a patient's participation in the study

- Patients who have been treated with any investigational drug or anti-cancer therapy
within 30 days of study start.