Analysis of predictors of response to ruxolitinib in patients with myelofibrosis in the phase 3b expanded-access JUMP study

Data from the large, prospective, multinational, phase 3b JUMP study were analyzed to identify factors predictive of spleen and symptom responses in myelofibrosis patients receiving ruxolitinib. Factors associated with higher spleen response rates included International Prognostic Scoring System (IPSS) low/intermediate-1 risk vs intermediate-2/high risk (43.1% vs 30.6%; adjusted OR aOR 0.65 95% CI 0.44-0.95), ruxolitinib as first- vs second- or later-line therapy (40.2% vs 31.5%; aOR 0.53 95% CI 0.38-0.75), and a ruxolitinib total daily dose at Week 12 of >20 mg/day vs ≤20 mg/day (41.3% vs 30.4%; aOR 0.47 95% CI 0.33-0.68). No association was seen between baseline characteristics or total daily dose at Week 12 and symptom response. Ruxolitinib led to higher spleen response rates in patients with lower IPSS risk, and when used earlier in treatment. Higher doses of ruxolitinib were associated with higher spleen response rates, but not with symptom improvement.Trial registrationINC424 for patients with primary myelofibrosis, post polycythemia myelofibrosis or post-essential thrombocythemia myelofibrosis (JUMP).2010-024473-39; NCT01493414Date of registration: 16 December 2011https://www.clinicaltrialsregister.eu/ctr-search/search?query=2010-024473-39https://clinicaltrials.gov/ct2/show/NCT01493414.