MPN-354 Characteristics of Patients With Myelofibrosis Taking Ruxolitinib for 3 or More Years.

Abstract

Ruxolitinib (RUX) was the first JAK1/2 inhibitor approved for patients with advanced-phase myelofibrosis (MF) with a median therapy duration of about 3 years. We aimed to characterize the clinical features of patients treated with RUX for ≥3 years. Retrospective review of medical records of 131 patients presented to our institution between January 2000 and July 2020 who received RUX for ≥3 years. Major clinical features were reported by descriptive statistics. OS was analyzed using the Kaplan-Meier model. The Cox proportional hazard model (univariate, multivariate) was used for factors associated with OS. The median age of patients was 67 years (range, 31-84) and 56% were men. Fewer than 20% of patients had hemoglobin <10 g/dL or platelets <150×109/L, and 30% had leukocytosis >25×109/L. Only 8% of patients had ≥3% circulating blasts. JAK2 mutation was present in 78% of patients. Among 62 patients with ≥28 gene next generation sequencing, 19, 24, and 19 patients had 0, 1, and ≥2 additional mutations, respectively. RUX as frontline therapy was given to 84% of patients. The median duration of RUX therapy was 76 months (95% CI, 56-88). At the time of last follow-up, 35% of patients continued on RUX. The most common disease-related reasons for discontinuation were MF progression (62%) and blastic phase (8%). The median OS since therapy was 90 months (95% CI, 76-104), and 40% of patients were alive at 10 years. Patients ≥65 years of age had a median OS of 76 months (95% CI, 67-85). Patients with high-risk DIPSS had a median OS of 72 months (95% CI, 55-89). The only factor retaining significance for OS in multivariate analysis was age >65 years (HR 2.7, 95% CI 1.50-4.14, P<0.001). Forty percent of patients who remained on RUX for ≥3 years were alive at 10 years since their therapy initiation. Age remains the major predictive factor of survival on long RUX therapy.