6/28/23, 11:10 PM Hydroxyurea versus anagrelide in high-risk ET Pathway Feedback Search Clinical Topics Home Studies Hydroxyurea versus anagrelide in high-risk ET Hydroxyurea versus anagrelide in high-risk ET Disease Essential thrombocythemia Trial question What is the role of hydroxyurea in patients with essential thrombocythemia? Study design Multi-center Open label RCT Population Characteristics of study participants 58.0% female N = 809 42.0% male 809 patients (467 female, 342 male) Inclusion criteria: patients with essential thrombocythemia who were at high-risk for vascular events and already receiving low-dose aspirin Key exclusion criteria: myelodysplasia or myelofibrosis, and known causes of reactive thrombocytosis, myocardial infarction within the previous three months, severe congestive HF, severe ventricular arrhythmia, pregnancy or lactation, or leg ulceration Interventions N=401 hydroxyurea (at a starting dose of 0.5-1.0 g daily, subsequent adjustment to maintain platelet count < 400,000 per m plus aspirin 75-100 mg daily) N=405 anagrelide (starting dose of 0.5 mg BID, subsequent adjustment to maintain platelet count < 400,000 per m plus aspirin 75-100 mg daily) Primary outcome Arterial or venous thrombosis, serious hemorrhage, or death from vascular causes https://web.pathway.md/studies/recqdKO9q1PVXZF6w 1/2 6/28/23, 11:10 PM Hydroxyurea versus anagrelide in high-risk ET Pathway 55.0 55 41.3 36 27.5 13.8 Significant increase 0.0 Hydroxyurea Anagrelide Significant increase in arterial or venous thrombosis, serious hemorrhage, or death from vascular causes (36 vs. 55; OR 1.57, 95% CI 1.04 to 2.37) Secondary outcomes Significant increase in arterial thrombosis (17 vs. 37; OR 2.16, 95% CI 1.27 to 3.69) Significant increase in serious hemorrhage (8 vs. 22; OR 2.61, 95% CI 1.27 to 5.33) Significant increase in transformation to myelofibrosis (5 vs. 16; OR 2.92, 95% CI 1.24 to 6.86) Safety outcomes Significant differences in study drug withdrawal due to side-effects (43 vs. 88, p < 0.001). Conclusion In patients with essential thrombocythemia who were at high-risk for vascular events and already receiving low-dose aspirin, hydroxyurea was superior to anagrelide with respect to arterial or venous thrombosis, serious hemorrhage, or death from vascular causes. Reference Harrison CN, Campbell PJ, Buck G et al. Hydroxyurea compared with anagrelide in high-risk essential thrombocythemia. N Engl J Med. 2005 Jul 7;353(1):33-45. Open reference URL https://web.pathway.md/studies/recqdKO9q1PVXZF6w 2/2