A Phase II Study of Re-treatment of Myelofibrosis Patients With Ruxolitinib/Jakavi After Treatment Interruption Due to Loss of Response and/or Adverse Event (ReTreatment Trial)

Inclusion Criteria: * Confirmed diagnosis of PMF, PPV MF or PET-MF, irrespective of JAK2 mutational status according to the 2008 revised International Standard Criteria * Peripheral blast count \< 10% * Requires therapy for MF in the opinion of the investigator * Received prior monotherapy treatment with ruxolitinib for at least 12 consecutive weeks and experienced treatment interruption because of lossof response or adverse event * Patients adhering to the Screening phase assessments and undergoing a a ruxolitinib-free washout period of a minimum of 1 week and a maximum of 8 weeks * ECOG performance status 0, 1, 2, or 3 * Adequate bone marrow function * Written informed consent Exclusion Criteria: * Patients not initially responding (primary resistance) to ruxolitinib therapy * Patients who underwent a splenectomy or spleen radiation * Patients currently scheduled for bone marrow transplant * Patients who have discontinued ruxolitinib \< 14 days prior to screening * Patients who are not able to receive a starting dose of ruxolitinib of at least 15 mg total daily dose * Leukemic transformation * Inadequate renal function * Presence of clinically meaningful active bacterial, fungal, parasitic or viral infection which requires therapy * Previous history of Progressive Multifocal Leuko-encephalopathy (PML) * Clinically significant cardiac disease or significant concurrent medical condition