Pb2192: jak2 v617f allele burden and thrombotic events in patients with jak2 v617f positive polycythemia vera or essential thrombocythemia at high risk of thrombosis

Topic: 16. Myeloproliferative neoplasms - Clinical Background: The goal of therapy of polycythemia vera (PV) and essential thrombocythemia (ET) is primarily to prevent vascular events that are the leading cause of morbidity and mortality. Patients older than 60 years or with a previous history of thrombotic complications are considered at high risk of thrombosis. Aims: The aim of this study was to explore the incidence of thrombotic events and long-term outcomes in high-risk patients with JAK2 V617F positive PV or ET. Methods: We retrospectively evaluated the clinical outcomes of JAK2 V617F positive PV and ET at a high risk of thrombosis. The patients older than 60 years of age and/or had a history of thrombosis at diagnosis among patients with JAK2 V617F positive PV or ET from Daegu Catholic University Hospital between 2010 and 2021 were included in this study. Results: A total of 112 patents, median age 73 years, with JAK2 V617F positive PV (n=50) or ET (n=62) were included. One hundred two patients were over 60 years old and 46 patients had a history of thrombosis or thrombotic event at diagnosis. All patients were treated with cytoreductive drugs. The cumulative incidence of thrombosis at 7 years was 29.9%, corresponding to 32.7% in PV and 29.2% in ET patients. Arterial thrombosis (93.8%) predominated in both diseases. Forty-five patients died during the follow-up period. Median overall survival was 125.1 months (95% CI 85.8-164.4). Median thrombosis-free survival was 86 months (95% CI 68.4-103.6). Older age (≥75 years old) and a higher JAK2 V617F allele burden (≥25%) were associated with poor thrombosis-free survival. Estimated rates of thrombosis-free survival at 7 years were 73.9% in the patients with lower JAK2 V617F allele burden (<25%) and 44.1% in the patients with higher JAK2 V617F allele burden (≥25%) (p=0.015). Eleven patients (9.7%) had secondary myelofibrosis, and one patient developed acute myeloid leukemia. Summary/Conclusion: A higher JAK2 V617F allele burden is associated with a higher risk of thrombotic events in patients with high-risk PV and ET. Current therapy remains suboptimal, with ongoing risk for thrombosis and death in high-risk PV and ET patients with higher JAK2 V617F allele burden. A novel approach will be needed in this group. Keywords: Essential Thrombocytemia, Polycythemia vera, Thromboembolic events