|Exclusion Criteria:||1) Subjects with a life expectancy of less than 6 months.|
2) Subjects in whom MF disease is well controlled with current therapy.
3) Subjects who are categorized as Low risk level by the DIPSS criteria
4) Females who are pregnant or are currently breastfeeding.
5) Subjects of childbearing potential who are unwilling to take appropriate precautions (from Screening through Follow-up) to avoid becoming pregnant or fathering a child. •Females of non-childbearing potential are defined as women who (a) are equal to or greater than 55 years of age with history of amenorrhea for 1 year, OR (b) are surgically sterile for at least 3 months. •For females of childbearing potential, or for males, appropriate precautions are those that are at least 99% effective in preventing the occurrence of pregnancy. These methods should be communicated to the subjects and their understanding confirmed: Complete abstinence from sexual intercourse Double barrier methods condom with spermicide in conjunction with use of an intrauterine device (IUD) condom with spermicide in conjunction with use of a diaphragm Oral, injectable, or implanted contraceptives Tubal ligation or vasectomy (surgical sterilization)
6) Subjects with recent history of inadequate bone marrow reserve as demonstrated by: •Subjects who have received platelet transfusion(s) or who have had ANC levels < 0.5 x109/L in the month prior to Screening.
7) Subjects with inadequate liver or renal function at Screening and Baseline visits as demonstrated by: •Direct bilirubin equal to or greater than 2.0 x the upper limit of laboratory normal (ULN). (NOTE: direct bilirubin will only be determined if total bilirubin is equal to or greater than 2.0 x ULN). •Alanine aminotransferase (ALT) > 2.5x ULN. •Modification of Diet in Renal Disease (MDRD) calculated GFR < 30 mL/min
8) Subjects with clinically meaningful, active bacterial, fungal, parasitic or viral infection which require therapy, or who are HIV positive (Subjects with acute infections requiring treatment should delay Screening/enrollment until the course of therapy has been completed and the event is considered resolved.)
9) Subjects with an invasive malignancy over the previous 2 years except treated basal or squamous carcinomas of the skin, completely resected intraepithelial carcinoma of the cervix and completely resected papillary thyroid and follicular thyroid cancers.
10) Subjects with recent severe or unstable cardiac disease
11) Subjects who have had splenic irradiation within 6 months prior to receiving the first dose of INCB039110.
12) "Subjects being treated concurrently with any prohibited medications, including investigational medication, rifampin, St. John's wort, and potent CYP3A4 inhibitors (excluding ketoconazole.) Refer to protocol section 8.9.2 and appendix 4 for more details."
13) Subjects who have previously received JAK inhibitor therapy for MF may be enrolled only with Sponsor approval.
14) Subjects with active alcohol or drug addiction that would interfere with their ability to comply with the study requirements.
15) Subjects with any concurrent condition that, in the Investigator's opinion, would jeopardize the safety of the subject or compliance with the protocol.
16) Subjects who have unknown transfusion history for at least the 12 weeks prior to Screening. All transfusions in this time period must be recorded in the electronic case report form (eCRF).
17) Subjects who are unable to complete the daily symptom diary, which is available in English, French and Spanish versions.