Inclusion Criteria:

- Men and Women at least 18 years old

- A diagnosis of symptomatic, primary or secondary Myelofibrosis (MF) [World Health
Organization (WHO) 2008 criteria] with intermediate-1, intermediate-2 or high risk
disease as assessed using the Dynamic International Prognostic Scoring System
international prognostic scoring system

- Last therapeutic or diagnostic treatment at least 28 days prior

- Any toxicity from prior therapies must have resolved to Grade ≤1

- Adequate Liver and Kidney Function

- Platelet count ≥50,000 cell mm³

- Absolute neutrophil count (ANC) ≥1,000 cells/mm3

- Hemoglobin ≥8.0 g/dL

Exclusion Criteria:

- Primary central nervous system tumors

- Subjects with currently active malignancy (other than MF) or with a prior history of
malignancy with the exception of: (i) adequately treated basal cell carcinoma of the
skin, (ii) curatively treated in situ carcinoma of the cervix, (iii) other malignancy
that has undergone potentially curative therapy with no evidence of disease
recurrence ≥3 years

- Any condition requiring chronic use of moderate/high dose steroids except inhalation
or oral steroids for mild pulmonary disease

- Splenic irradiation ≤3 months prior to treatment with study drug

- Positive blood screen for hepatitis C antibody, hepatitis B surface antigen or Human
Immunodeficiency Virus-1 (HIV-1), or HIV-2 antibodies

- Abnormalities in serum electrolytes

- Significant cardiovascular disease

- Current or recent gastrointestinal disease

- Evidence of uncontrolled active infection or active graft vs. host disease

- Inability to tolerate oral medication