Inclusion Criteria:

   - Diagnosis of PMF or post-polycythemia Vera (PV) or post-essential Thrombocythemia (ET)
   MF as per revised World Health Organization (WHO) criteria.

   - High-risk or Intermediate-2 risk MF (as defined by the International Prognostic
   Scoring System [IPSS]; Appendix 13.6); or intermediate-I risk MF (IPSS) associated
   with symptomatic splenomegaly/hepatomegaly and/or unresponsive to available therapy.

   - Must be at least 18 years of age with life expectancy of ≥ 12 weeks.

   - Must be able to provide informed consent and be willing to sign an informed consent
   form.

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

   - Must have evidence of acceptable organ function within 7 days of initiating study drug
   as evidenced by the following:

      - Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) ≤ 2.5 x upper
      limit of normal (ULN) (or ≤ 5 x ULN if in the investigator's opinion the
      elevation is due to extramedullary hematopoiesis)

      - Bilirubin ≤ 2.0 x ULN or direct bilirubin < 1.0

      - Serum creatinine ≤ 2.5 x ULN

      - Absolute neutrophil count ≥ 500/µL

      - Platelet count ≥ 50,000/µL

   - Females of childbearing potential must have a negative pregnancy test within 4 days of
   initiating study drug.

Exclusion Criteria:

   - Any chemotherapy (eg, hydroxyurea), immunomodulatory drug therapy (eg, thalidomide),
   immunosuppressive therapy, corticosteroids > 10 mg/day prednisone or equivalent, or
   growth factor treatment (eg, erythropoietin) within 14 days prior to initiation of
   study drug.

   - Incomplete recovery from major surgery within four weeks of study entry.

   - Radiation therapy within four weeks of study entry.

   - Women of childbearing potential, unless surgically sterile for at least 3 months (ie,
   hysterectomy), OR postmenopausal for at least 12 months (FSH > 30 U/mL), OR unless
   they agree to take appropriate precautions to avoid pregnancy (with at least 99%
   certainty) from screening through end of study. Permitted methods for preventing
   pregnancy must be communicated to study subjects and their understanding confirmed.

   - Men who partner with a woman of childbearing potential, unless they agree to take
   appropriate precautions to avoid pregnancy (with at least 99% certainty) from
   screening through to the end of study. Permitted methods for preventing pregnancy must
   be communicated to study subjects and their understanding confirmed.

   - Females who are pregnant or are currently breastfeeding.

   - Known positive status for HIV.

   - Clinically active hepatitis B or C.

   - Diagnosis of another malignancy unless free of disease for at least three years
   following therapy with curative intent. Patients with early-stage basal cell or
   squamous cell skin cancer, cervical intraepithelial neoplasia, cervical carcinoma in
   situ or superficial bladder cancer may be eligible to participate at the
   Investigator's discretion.

   - Any acute active infection.

   - Cardiac dysrhythmias requiring treatment, or prolongation of the QTc (Fridericia)
   interval to > 450 msec for males or > 470 msec for females at prestudy screening,
   unless attributable to pre-existing bundle branch block.

   - Presence of ≥ Grade 2 peripheral neuropathy.

   - Uncontrolled congestive heart failure (New York Heart Association Classification 3 or
   4), uncontrolled or unstable angina, myocardial infarction, cerebrovascular accident,
   or pulmonary embolism within 3 months prior to initiation of study drug.

   - Uncontrolled inter current illness or any concurrent condition that, in the
   Investigator's opinion, would jeopardize the safety of the patient or compliance with
   the protocol.