An Open Label Study of Itacitinib Administered Orally in Patients With Myelofibrosis

Inclusion Criteria:

Must be diagnosed with PMF, PPV-MF or PET-MF as confirmed by bone marrow biopsy.
Must score at least 1 point on the Dynamic International Prognostic Scoring System (DIPSS) for prognostic risk factors and have peripheral blast count <10% at both Screening and Baseline hematology assessments.
Subjects must discontinue all drugs used to treat underlying MF disease no later than Day -14.
Subjects must have hemoglobin value >/= 8.0g/dL and be willing to receive blood transfusions, have a platelet count >/=50x10^9/L and absolute neutrophil count (ANC) >/= 1x10^9/L.
Subjects must have palpable spleen or history of splenectomy
Active symptoms at the screening visit

Exclusion Criteria:

Women who are pregnant or breastfeeding, and men and women who cannot comply with requirements to avoid fathering a child or becoming pregnant, respectively.
Subjects with impaired liver function, end stage renal disease on dialysis or clinically significant concurrent infections requiring therapy.
Subjects with unstable cardiac function or invasive malignancies 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.