Background: An unmet need for therapies exists to reduce sickle cell disease (SCD) complications in pediatric patients. Activated platelets contribute to the formation of cellular aggregates during sickling and vaso-occlusive crises (VOCs). Ticagrelor is an oral, direct-acting, and reversible adenosine diphosphate P2Y12 receptor antagonist that inhibits platelet activation and aggregation. Although ticagrelor was well tolerated in two phase 2 studies in children and young adults with SCD, larger and longer-term treatment studies are needed to assess ticagrelor's efficacy to reduce VOCs. HESTIA3 will evaluate the efficacy, safety, and tolerability of ticagrelor versus placebo over a minimum of 1 year (maximum 2 years) in pediatric patients with SCD. Methods: Approximately 180 patients (aged ≥ 2 to <18 years) with SCD (≥ 2 VOCs in the prior year) from 18 countries will be randomized 1:1 to ticagrelor or placebo. Primary endpoint: number of VOCs (a composite endpoint of painful crises and/or acute chest syndrome); key secondary endpoints: hospitalizations, pain intensity and analgesic use during VOCs, acceptability of formulation, and health-related quality of life. The weight-based doses of ticagrelor are set by modeling and simulation. Platelet inhibition data, measured by the vasodilator-stimulated phosphoprotein assay, will be collected for exploratory purposes. Conclusions: HESTIA3 aims to demonstrate that using greater target platelet inhibition than previous studies on SCD, ticagrelor will decrease the frequency of VOC in pediatric patients. Trial Identifier: NCT03615924; EudraCT2017-002421-38.
