Ruxolitinib is widely used in Polycythemia Vera (PV) following hydroxyurea failure. However, validated response criteria to predict long-term outcomes in ruxolitinib-treated patients are lacking, complicating clinical decision-making. We investigated predictors of event-free survival (EFS, including progression to post-PV myelofibrosis, thrombosis, hemorrhages, or death) after 6 months of ruxolitinib in 178 PV patients enrolled in the observational PV-ARC study (NCT06134102). After a median follow-up from ruxolitinib start of 3.50 years, 15 patients died, 7 had a thrombosis, 9 a hemorrhage, and 21 progressed to myelofibrosis. Overall, 5-year EFS was 70.4%. Leukocytosis (10x109/L), thrombocytosis (400x109/L), phlebotomy need, lack of spleen length reduction ≥50% (SR50) and ruxolitinib dose 10 mg BID at three timepoints (baseline, month 3 and 6), were tested for association with EFS. Multivariable analysis identified three independent risk factors: (1) ruxolitinib dose10mg BID at ≥1 timepoint (HR 1.94, p=0.047), (2) no SR50 at months 3 and 6 (HR 2.65, p=0.009), (3) phlebotomy requirement at ≥2 timepoints (HR 2.11, p=0.039). Points were assigned as follows: 1 to phlebotomies at one timepoint; 2 to phlebotomies at ≥2 timepoints and to ruxolitinib 10 mg BID at ≥1 timepoint; 2.5 to lack of SR50. Based on cumulative scores, we developed the PV-Response to Ruxolitinib after 6 Months (PV-RR6) prognostic model, identifying three risk categories: low (score 0, 5-year EFS: 89.4%, n=63), intermediate (score 1-2.5, EFS: 71.0%, n=82), and high (score 2.5, EFS: 38.9%, n=33) (p0.001). PV-RR6 enables early identification of patients at risk of poor outcomes, supporting timely treatment optimization in ruxolitinib-treated patients.
Palandri et al. (Thu,) studied this question.