Primary analysis of JUMP, a phase 3b, expanded-access study evaluating the safety and efficacy of ruxolitinib in patients with myelofibrosis, including those with low platelet counts

Br J Haematol. 2020 Jun;189(5):888-903. doi: 10.1111/bjh.16462. Epub 2020 Feb 4.

Abstract

Ruxolitinib is a potent Janus kinase (JAK) 1/JAK2 inhibitor approved for the treatment of myelofibrosis (MF). Ruxolitinib was assessed in JUMP, a large (N = 2233), phase 3b, expanded-access study in MF in countries without access to ruxolitinib outside a clinical trial, which included patients with low platelet counts (<100 × 109 /l) and patients without splenomegaly - populations that have not been extensively studied. The most common adverse events (AEs) were anaemia and thrombocytopenia, but they rarely led to discontinuation (overall, 5·4%; low-platelet cohort, 12·3%). As expected, rates of worsening thrombocytopenia were higher in the low-platelet cohort (all grades, 73·2% vs. 53·5% overall); rates of anaemia were similar (all grades, 52·9% vs. 59·5%). Non-haematologic AEs, including infections, were mainly grade 1/2. Overall, ruxolitinib led to meaningful reductions in spleen length and symptoms, including in patients with low platelet counts, and symptom improvements in patients without splenomegaly. In this trial, the largest study of ruxolitinib in patients with MF to date, the safety profile was consistent with previous reports, with no new safety concerns identified. This study confirms findings from the COMFORT studies and supports the use of ruxolitinib in patients with platelet counts of 50-100 × 109 /l. (ClinicalTrials.gov identifier NCT01493414).

Keywords: myelofibrosis; ruxolitinib; safety; splenomegaly; symptoms.

Publication types

  • Clinical Trial, Phase III
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Anemia / chemically induced
  • Female
  • Humans
  • Janus Kinase 1 / antagonists & inhibitors
  • Janus Kinase 2 / antagonists & inhibitors
  • Kaplan-Meier Estimate
  • Leukemia, Myeloid, Acute / etiology
  • Male
  • Middle Aged
  • Neoplasms / etiology
  • Nitriles
  • Platelet Count
  • Primary Myelofibrosis / blood
  • Primary Myelofibrosis / complications
  • Primary Myelofibrosis / drug therapy*
  • Progression-Free Survival
  • Proportional Hazards Models
  • Protein Kinase Inhibitors / adverse effects
  • Protein Kinase Inhibitors / therapeutic use*
  • Pyrazoles / adverse effects
  • Pyrazoles / therapeutic use*
  • Pyrimidines
  • Spleen / pathology
  • Splenomegaly / etiology
  • Thrombocytopenia / chemically induced
  • Young Adult

Substances

  • Nitriles
  • Protein Kinase Inhibitors
  • Pyrazoles
  • Pyrimidines
  • ruxolitinib
  • JAK1 protein, human
  • JAK2 protein, human
  • Janus Kinase 1
  • Janus Kinase 2

Associated data

  • ClinicalTrials.gov/NCT01493414