Inclusion Criteria

Inclusion Criteria

- During the dose escalation phase: subjects with histologically confirmed myeloid
malignancy who have failed standard therapies or are not candidates for palliative
therapies. This includes the following:

- Subjects with Acute Myelogenous Leukemia (AML)

- Subjects with Chronic Myelogenous Leukemia (CML) in accelerated phase

- Subjects with Chronic Myelogenous Leukemia (CML) in blast crisis

- Subjects with high-risk Myelodysplastic Syndromes (MDS) or Chronic
Myelomonocytic Leukemia (CMML)

- Subjects with Advanced Myelofibrosis (MF)

- In Phase 2, subjects with CIMF (as well as post ET/PV MF)

- Eastern Cooperative Oncology Group (ECOG) performance status 0-2

- All men of reproductive potential and women of child-bearing potential must agree to
practice effective contraception during the entire study period and for one month
after the last study treatment, unless documentation of infertility exists.
Additionally, women of child-bearing potential must have a negative pregnancy test
within 14 days prior to the first dose of study drug

- Able to understand and willing to sign the informed consent form

Exclusion Criteria

- Subjects with Chronic Myelogenous Leukemia (CML) in chronic phase;

- Uncontrolled inter-current illness including, but not limited to, ongoing active
infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac
arrhythmia, or psychiatric illness/social situations that would limit compliance with
study requirements as judged by treating physician. Subjects receiving antibiotics
for infections that are under control may be included in the study;

- Concurrent malignancy, except those subjects with early stage squamous cell carcinoma
of the skin, basal cell carcinoma of the skin, or cervical intraepithelial neoplasia
are eligible for the study;

- Known HIV-positive (such subjects are at increased risk of lethal infections when
treated with potentially marrow-suppressive therapy);

- Known active hepatitis A, B, or C;

- Women who are pregnant or lactating.