MPN-070: Real-World Dosing Patterns of Ruxolitinib in Patients with Polycythemia Vera Who are Resistant to or Intolerant of Hydroxyurea

Context: Up to 40% of patients with polycythemia vera (PV) become resistant and/or intolerant to hydroxyurea. Ruxolitinib, a Janus kinase 1 and 2 inhibitor, is currently the only FDA-approved treatment for patients with hydroxyurea-resistant/intolerant PV. Objective: To characterize the reasons patients were switched from hydroxyurea to ruxolitinib and describe real-world dosing patterns of ruxolitinib in patients with PV. Design, Setting, and Patients: This retrospective medical chart review was conducted at US community hematology/oncology practices in the Cardinal Health Oncology Provider Extended Network. Eligible patients were ≥18 years old, initiated ruxolitinib during the index period (01 Jan, 2015–31 Dec, 2016), had previously received hydroxyurea for ≥3 months, and were seen ≥2 times over 6 months post–ruxolitinib initiation. Data were collected for 12 months prior to ruxolitinib initiation, near ruxolitinib initiation, and until the last provider visit. Main Outcomes and Measures: Clinical characteristics including blood counts, symptoms, phlebotomy, and ruxolitinib treatment patterns Results: Providers identified 249 patients for inclusion. Primary causes of hydroxyurea discontinuation were resistance (78%), intolerance (28%), patient choice (23%), and other (4%); 14% were both resistant and intolerant. The most frequent reasons for hydroxyurea discontinuation due to resistance were hematocrit ≥45% (79%), symptoms (63%), leukocytosis (38%), and thrombocytosis (38%). The most frequent intolerance signs/symptoms were nausea/vomiting (50%), stomatitis (37%), skin ulcers (23%), and fever (9%). One-hundred thirty-one patients (53%) initiated ruxolitinib at 10 mg twice daily (BID; recommended dose); median (range) treatment duration was 29.2 (11.2–37.1) months. Of these patients, 35 (27%) required dose modification (increase, n=24; decrease, n=11) within the first 6 months; 4 patients had interruptions. The most common reasons for dose increase were continued need for phlebotomy (46%) and persistent symptoms (38%); 6 patients had dose reductions owing to reduced platelets. 12% of patients required dose modifications after 6 months. Hematocrit control (hematocrit Conclusions: Among patients with PV who switched from hydroxyurea to ruxolitinib, approximately half initiated ruxolitinib at the recommended dose (10 mg BID). Of these patients, 27% experienced dosing modifications within the first 6 months; need for modification decreased over time.