Inclusion criteria

Patients eligible for inclusion in this Treatment Plan have to meet all of the following
criteria:

Written patient informed consent must be obtained prior to start of treatment. Patients
ineligible for other ruxolitinib trials could be eligible for this MAP. 1. Patients must be ≥12 years and diagnosed with PMF, according to the 2016 revised International Standard Criteria (Arber et al. 2016), PPV MF or PET-MF (Barosi 2008), irrespective of JAK2 mutation status. 2. Patients with a peripheral blood blast percentage count of < 10%. 3. Patients must have recovered or stabilized sufficiently from any adverse drug reactions associated with prior treatments before beginning treatment with ruxolitinib. - Patients who were pre-treated with Fedratinib should have complete physical examination including full neurologic examination and cardiology assessment including thiamine levels. MRI of the brain should be considered if indicated based on the signs or symptoms.

Exclusion criteria

Patients eligible for this Treatment Plan must not meet any of the following criteria: 1. History of hypersensitivity to any drugs or metabolites of similar chemical classes as ruxolitinib. 2. Presence of an active uncontrolled infection including significant bacterial, fungal, viral 3. History of progressive multifocal leuko-encephalopathy. 4. Presence of severely impaired renal function defined by serum creatinine > 2 mg/dL (>176.8 μmol/L), or have estimated creatinine clearance < 30 ml/min measured or calculated by Cockroft Gault equation. 5. Women of child-bearing potential, defined as all women physiologically capable of becoming pregnant, - women whose sexual orientation precludes intercourse with a male partner. - women whose partners have been sterilized by vasectomy or other means. - using a highly effective method of birth control 6. Not able to understand and to comply with treatment instructions and requirements.