Background: Myelofibrosis (MF) can be primary in origin or can progress from polycythemia vera (PPV-MF) or essential thrombocythemia (PET-MF). MF is characterized by cytopenias, reactive bone marrow fibrosis, splenomegaly, and constitutional symptoms including weight loss, fever, and night sweats. MF is associated with dysregulation of the Janus kinase pathway, irrespective of JAK2V617F mutation status. Recently, ruxolitinib (INCB018424) was approved for the treatment of MF on the basis of results from 2 phase 3 trials (COMFORT-I and -II). These trials demonstrated marked reductions in splenomegaly and symptom burden, and improvements in health-related quality of life (QoL) measures. Methods: JAK Inhibitor rUxolitinib in Myelofibrosis Patients (JUMP) is a global, phase 3b expanded access trial (NCT01493414) designed to assess the safety and efficacy of ruxolitinib in adult pts with PMF, PPV-MF or PET-MF who are treatment naïve, and are intolerant of, or had progressed on any prior therapy. Inclusion criteria: peripheral blast count of <10%, adequate liver and renal function and intermediate-2 or high risk MF according to IPSS criteria or intermediate-1 risk MF with palpable spleen length ≥ 5 cm. The primary endpoint is to assess the safety of ruxolitinib. Additional endpoints include the proportion of pts with a > 50% reduction in palpable spleen length, % change in white blood cell and platelet counts from baseline (BL), and change in packed red blood cell transfusion requirements. Changes from BL in QoL scores will be assessed using validated ECOG PS, FACT-Lymphoma, and FACIT instruments. Pts with a BL platelet count > 200,000/μL will receive oral ruxolitinib 20 mg BID; pts with a BL platelet count of 100,000/μL to 200,000/μL will receive 15 mg BID; dose modifications are permitted for safety and efficacy. Global enrollment is open and currently includes 277 pts. This is planned to be the largest study ever conducted in pts with MF.

Country	# of Pts
Austria	24
Belgium	15
Brazil	24
Germany	173
Spain	28
Argentina	3
Canada	3
Netherlands	3
Italy	4
Total	277