ticagrelor and Anemia--Sickle-Cell

Ticagrelor is an antiplatelet agent approved for the treatment of patients with an acute coronary syndrome or a history of myocardial infarction. Considering the evidence demonstrating that ticagrelor-mediated inhibition of platelet activation and aggregation have beneficial effects in the treatment of thrombotic conditions, clinical studies have been conducted to evaluate the use of this drug for the treatment of sickle cell disease (SCD), demonstrating satisfactory tolerability and safety.. Clinical investigation has characterized the pharmacokinetic and pharmacodynamical profile, as well as the efficacy and safety of ticagrelor to prevent painful vaso-occlusive crisis (painful episodes and acute chest syndrome) in SCD patients.. While phase 1 and 2 clinical trials demonstrated satisfactory tolerability and safety, the conclusion of phase 3 clinical trials is crucial to prove the efficacy of ticagrelor as a therapeutic option for the treatment of SCD. Thus, it is expected that ticagrelor, especially in combination with other drugs, will improve the clinical profile and quality of life of patients with SCD.

Topics: Anemia, Sickle Cell; Blood Coagulation; Clinical Trials, Phase I as Topic; Clinical Trials, Phase II as Topic; Clinical Trials, Phase III as Topic; Drug Monitoring; Humans; Molecular Structure; Platelet Activation; Platelet Aggregation Inhibitors; Purinergic P2Y Receptor Antagonists; Thrombophilia; Ticagrelor; Treatment Outcome

Sickle cell disease (SCD) is the most common hemoglobinopathy, occurring worldwide, and vaso-occlusive events (VOEs) are its paramount, hallmark clinical manifestation. Evidence exists that platelets play an important role in generating VOEs.. To assess the clinical benefits and harms of antiplatelet agents for preventing VOEs in patients with SCD.. We conducted searches of the Cochrane Central Register of Controlled Trials (CENTRAL; up to 2018, issue 3 of 12), PubMed/MEDLINE (up to April 20, 2018), and the Excerpta Medica database (EMBASE; from 1980 to week 16 of 2018). We also searched the Latin American and Caribbean Health Sciences Literature (LILACS) database, the US Food and Drug Administration (FDA) website, the European Medicines Agency (EMA) website, the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP), and www.ClinicalTrials.gov. We checked the bibliographies of included studies and any relevant systematic reviews. Our systematic review included randomized clinical trials (RCTs) conducted in people who had SCD without VOEs at trial entry. Eligible trials compared a single or combination treatment regimen (with each treatment classified as a conventional or nonconventional antiplatelet agent) with conventional care, placebo, or another regimen. No restrictions were placed on the route of administration, dose, frequency, or duration of treatment. We selected RCTs, assessed the risk for bias, and extracted data in a duplicate and independent fashion. We estimated risk ratios for dichotomous outcomes and mean differences for continuous outcomes. We also subjected our analyses to a random-effects model, and Trial Sequential Analysis (TSA) was used. We used the grading of recommendations, assessment, development, and evaluation (GRADE) approach to assess the overall quality of data for each individual outcome.. We identified 5 RCTs (N=747) that met our criteria. Of these, 4 trials were multicenter and multinational. The trials included patients of all ages and assessed prasugrel, ticagrelor, crizanlizumab, and aspirin vs either placebo or no intervention. The most frequent route of administration was oral. The trials were small and carried a high risk for bias, given that pharmaceutical companies sponsored 4 of them. None of the trials reported information on quality of life. No meta-analysis was performed owing to heterogeneity in the ages of the participants and in the interventions. No single trial showed evidence of certainty regarding all-cause mortality. One trial showed uncertainty in comparing prasugrel vs placebo for preventing VOEs in patients younger than 18 years (relative risk [RR], 0.92; 95% CI, 0.80 to 1.06; low quality of evidence). TSA for this outcome suggested that a new trial should be conducted. One trial found a difference in the size effect of uncomplicated VOEs, favoring high-dose crizanlizumab vs placebo (mean difference, -1.50; 95% CI, -2.61 to -0.39; very low quality of evidence). No difference in VOEs was found in studies that compared either ticagrelor in children or prasugrel in adults vs placebo. The overall incidence of harms in any intervention did not differ from that in the control.. The current evidence does not support or reject the use of any antiplatelet agent for preventing VOEs in people with SCD. This conclusion was based on small RCTs that carried a high risk for bias. No conclusive evidence exists regarding relevant clinical outcomes because the evidence is limited and of very low quality.

Topics: Adult; Anemia, Sickle Cell; Antibodies, Monoclonal, Humanized; Hemorrhage; Humans; Mortality; Multicenter Studies as Topic; Platelet Aggregation Inhibitors; Prasugrel Hydrochloride; Randomized Controlled Trials as Topic; Ticagrelor; Treatment Outcome; Vascular Diseases

The phase 3 HESTIA3 study assessed the efficacy and safety of the reversible P2Y12 inhibitor ticagrelor vs placebo in preventing vaso-occlusive crises in pediatric patients with sickle cell disease (SCD). Patients aged 2 to 17 years were randomly assigned 1:1 to receive weight-based doses of ticagrelor or matching placebo. The primary end point was the rate of vaso-occlusive crises, a composite of painful crises and/or acute chest syndrome (ACS). Key secondary end points included number and duration of painful crises, number of ACS events, and number of vaso-occlusive crises requiring hospitalization or emergency department visits. Exploratory end points included the effect of ticagrelor on platelet activation. In total, 193 patients (ticagrelor, n = 101; placebo, n = 92) underwent randomization at 53 sites across 16 countries. The study was terminated 4 months before planned completion for lack of efficacy. Median ticagrelor exposure duration was 296.5 days. The primary end point was not met: estimated yearly incidence of vaso-occlusive crises was 2.74 in the ticagrelor group and 2.60 in the placebo group (rate ratio, 1.06; 95% confidence interval, 0.75-1.50; P = .7597). There was no evidence of efficacy for ticagrelor vs placebo across secondary end points. Median platelet inhibition with ticagrelor at 6 months was 34.9% predose and 55.7% at 2 hours' postdose. Nine patients (9%) in the ticagrelor group and eight patients (9%) in the placebo group had at least one bleeding event. In conclusion, no reduction of vaso-occlusive crises was seen with ticagrelor vs placebo in these pediatric patients with SCD. This trial was registered at www.clinicaltrials.gov as #NCT03615924.

Topics: Acute Chest Syndrome; Anemia, Sickle Cell; Child; Hemorrhage; Humans; Pain; Platelet Aggregation Inhibitors; Ticagrelor

Inhibition of platelet activation may reduce vaso-occlusion rates in patients with sickle cell disease (SCD). In the HESTIA4 (NCT03492931) study, 21 children with SCD received a single oral dose of the antiplatelet agent ticagrelor (0.1 mg/kg <6 months; 0.2 mg/kg ≥6 to <24 months). All patients had measurable ticagrelor plasma concentrations. Ticagrelor and active metabolite (AR-C124910XX) exposure were comparable across all groups (<6 months, ≥6 to <12 months and ≥12 to <24 months). Ticagrelor was well tolerated. Palatability was generally acceptable. These data will be used to enable dose selection for further investigations of ticagrelor efficacy and safety in children with SCD.

Topics: Anemia, Sickle Cell; Female; Humans; Infant; Infant, Newborn; Male; Platelet Aggregation; Platelet Aggregation Inhibitors; Ticagrelor

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 P2Y. 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.. 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.

Topics: Adolescent; Anemia, Sickle Cell; Child; Child, Preschool; Clinical Trials, Phase III as Topic; Double-Blind Method; Female; Humans; Male; Multicenter Studies as Topic; Platelet Aggregation Inhibitors; Randomized Controlled Trials as Topic; Research Design; Ticagrelor

Ticagrelor is an antiplatelet agent for adults with coronary artery disease. The inhibition of platelet activation may decrease the frequency of vaso-occlusion crisis (VOC) in sickle cell disease (SCD). The HESTIA2 study (NCT02482298) randomised 87 adults with SCD (aged 18-30 years) 1:1:1 to twice-daily ticagrelor 10, 45 mg or placebo for 12 weeks. Numerical decreases from baseline in mean proportion of days with patient-reported pain (primary endpoint) were seen in all three groups, as well as in pain intensity and analgesic use, with no significant differences between placebo and ticagrelor treatment groups. Plasma ticagrelor concentrations and platelet inhibition increased with dose. Adverse events were distributed evenly across groups and two non-major bleeding events occurred per group. Ticagrelor was well tolerated with a low bleeding risk, but no effect on diary-reported pain was detected. Potential effects on frequency of VOCs will need to be evaluated in a larger and longer study.

Topics: Adolescent; Adult; Analgesics; Anemia, Sickle Cell; Female; Humans; Male; Pain; Platelet Aggregation Inhibitors; Ticagrelor; Young Adult

An adult population PK model was refined to describe ticagrelor and AR-C124910XX (active metabolite) plasma concentration and time data over a wide range of single/repeated ticagrelor doses (0.125-2.25 mg/kg). Population PK/PD modeling was used to describe the time course and extent of platelet inhibition. Demographic covariate relationships were investigated.. The final population PK model adequately described ticagrelor and AR-C124910XX plasma concentrations over time. An allometric body weight relationship between ticagrelor and AR-C124910XX clearances and volumes of distribution was used. Significant covariates for ticagrelor were sex (relative bioavailability) and cholecystectomy (central volume of distribution). Estimated oral clearances (35 kg patient; median bodyweight) were 22.8 L/h (ticagrelor) and 9.97 L/h (AR-C124910XX). The final population PK/PD model well-described the time course and extent of platelet inhibition. Estimated baseline PRU was 283, maximum PRU effect was fixed at 1, and the ticagrelor concentration for half-maximum PRU effect was 233 nmol/L.. These analyses offer the first quantitative characterization of the dose-exposure-response relationship for ticagrelor in pediatric SCD patients. This model-based approach may be used to inform dose selection and design of subsequent studies that aim to define ticagrelor safety and efficacy in pediatric SCD patients.

Topics: Adolescent; Anemia, Sickle Cell; Child; Child, Preschool; Dose-Response Relationship, Drug; Double-Blind Method; Female; Humans; Male; Models, Biological; Platelet Aggregation Inhibitors; Purinergic P2Y Receptor Antagonists; Ticagrelor

Topics: Adolescent; Anemia, Sickle Cell; Child; Child, Preschool; Dose-Response Relationship, Drug; Drug Administration Schedule; Humans; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Function Tests; Ticagrelor; Treatment Outcome

Topics: Anemia, Sickle Cell; Child; Hemoglobinopathies; Humans; Ticagrelor