Study of the JAK Inhibitor Ruxolitinib Administered Orally to Patients With Primary Myelofibrosis (PMF), Post-Polycythemia Vera-Myelofibrosis (PPV-MF) or Post-Essential Thrombocythemia-Myelofibrosis (PET-MF)

DLT was defined as the occurrence of any of the following treatment-related toxicities, occurring through Day 28: Any grade ≥ 2 hemorrhagic event ; Any grade thrombocytopenia requiring PLT transfusion; PLT count < 25x109/L*; Grade 4 neutropenia (absolute neutrophil count < 0.5x109/L)*; Grade ≥ 3 febrile neutropenia*; Grade ≥ 2 total serum bilirubin with coincident direct bilirubin ≥ 0.5 mg/dL; Grade 3 non-hematologic toxicity for ≥ 7 consecutive days; Grade 4 non-hematologic toxicity. In the dose escalation stage in the core study period, the starting does in both strata was 5mg bid. Successive cohorts of newly enrolled patients received increasing doses of ruxolitinib until the Maximum Safe Starting Dose (MSSD) was determined. Initially, only patients with PLT counts 75-99 x10^9/L (stratum 1) were allowed to be enrolled. Once safety was established in stratum 1 at the first 2 dose cohorts, eligible population was further expanded to patients with PLT counts 50-74 x10^9/L (stratum 2).

Adverse events reported for the first time or worsening of a pre-existing event after first dose of study drug/treatment.

Participants achieving ≥ 50% reduction in palpable spleen length relative to study day 1 by treatment and stratum

Defined as measurement of change in spleen length by palpation from baseline

To define the PK and C Reactive Protein relationship using PK Quartiles (AUC 0-12, ng*h/mL)

To define the PK and Interleukin 1 Receptor Antagonist relationship relationship using PK Quartiles (AUC 0-12, ng*h/mL)

To define the PK and Tissue Necrosis Factor Receptor 2 relationship using PK Quartiles (AUC 0-12, ng*h/mL)

Area Under the Serum Concentration Versus Time Curve，Time 0 to Infinity