Real-world survival of US patients with intermediate- to high-risk myelofibrosis: impact of ruxolitinib approval

The Janus kinase inhibitor ruxolitinib is approved for the treatment of myelofibrosis (MF) and improved overall survival (OS) versus control therapy in the phase 3 COMFORT trials. The aim of this retrospective analysis was to examine the real-world impact of ruxolitinib on OS in patients with MF. The US Medicare Fee-for-Service claims database (parts A/B/D) was used to identify patients with ≥ 1 inpatient or ≥ 2 outpatient claims with an MF diagnosis (January 2010-December 2017). Eligible patients with MF were ≥ 65 years old (intermediate-1 or higher risk based on age). Patients were divided into 3 groups based on ruxolitinib approval status at diagnosis and ruxolitinib exposure: (1) preapproval, ruxolitinib-unexposed; (2) post-approval, ruxolitinib-unexposed; and (3) post-approval, ruxolitinib-exposed. In total, 1677 patients with MF were included (preapproval all ruxolitinib-unexposed, n = 278; post-approval, n = 1399 ruxolitinib-unexposed, n = 1127; ruxolitinib-exposed, n = 272). Overall, median age was 78 years, and 39.8% were male. Among patients with valid death dates (preapproval, n = 119 42.8%; post-approval, ruxolitinib-unexposed, n = 382 33.9%; post-approval ruxolitinib-exposed, n = 54 19.9%), 1-year survival rates were 55.6%, 72.5%, and 82.3%, and median OS was 13.2 months, 44.4 months, and not reached, respectively. Risk of mortality was significantly lower post- versus preapproval regardless of exposure to ruxolitinib (ruxolitinib-unexposed: adjusted hazard ratio HR, 0.67; ruxolitinib-exposed: adjusted HR, 0.36; P < 0.001 for both); post-approval, mortality risk was significantly lower in ruxolitinib-exposed versus ruxolitinib-unexposed patients (adjusted HR, 0.61; P = 0.002). Findings from this study complement clinical data of ruxolitinib in MF by demonstrating a survival benefit in a real-world setting.