|Exclusion Criteria:||1) Active, uncontrolled systemic infection.|
2) Patients with any unresolved toxicity (regardless of organs) greater than Grade 1 from previous anticancer therapy.
3) Prior treatment with JAK2 inhibitors that necessitated discontinuation specifically due to gastrointestinal toxicity.
4) Potentially curative therapy is available: • Candidates for hematopoietic stem cell transplant in which transplant is an available and viable option and of higher priority than this study are excluded; • If the patient has declined hematopoietic stem cell transplant, has no donor for transplant, or in the judgment of the investigator is not suitable for transplant, the patient may be enrolled.
5) Currently taking medication that is substantially metabolized by cytochrome P450 (CYP) 1A2 or CYP3A4 or taking medication known to be strong inhibitors or inducers of CYP3A4
6) Patients with a serious cardiac condition within the past 6 months such as uncontrolled arrhythmias, myocardial infarction, angina or heart disease as defined by the New York Heart Association (NYHA) Class III or IV
7) Pregnant or lactating.
8) Radiation therapy for splenomegaly within 6 months prior to study entry (screening).
9) Splenectomy (applicable to patients enrolling in the Phase 2 portion of the study only).
10) Known HIV positive status.
11) Known active hepatitis, a history of viral hepatitis B or hepatitis C, or known positive hepatitis B serologies without a history of immunization.
12) Other concurrent disease and/or medical condition, which, in the judgment of the investigator, would prevent the patient's participation.
13) Patients diagnosed with another malignancy, unless they are disease free. Patients with early stage squamous cell carcinoma of the skin, basal cell carcinoma of the skin, or cervical intraepithelial neoplasia may be eligible for participation at the investigator's discretion.
14) Patients who have had surgery (other than placement of vascular access and bone marrow biopsy) within 4 weeks of study entry (screening), or patients with incomplete recovery from any prior surgical procedures.
15) Patients actively receiving a concurrent investigational agent.
16) Unwilling or unable to comply with the protocol.