Impact of adenosine A2a receptor polymorphism rs5751876 on platelet reactivity in ticagrelor treated patients

Pharmacogenetic considerations in therapy with novel antiplatelet and anticoagulant agents

Antiplatelets and anticoagulants are extensively used in cardiovascular medicine for the prevention and treatment of thrombosis in the venous and arterial circulations. Wide inter-individual variability has been observed in response to antiplatelets and anticoagulants, which triggered researchers to investigate the genetic basis of this variability. Data from extensive pharmacogenetic studies pointed to strong evidence of association between polymorphisms in candidate genes and the pharmacokinetics and pharmacodynamic action and clinical response of the antiplatelets clopidogrel and the anticoagulant warfarin. In this review, we conducted an extensive search on Medline for the time period of 2009-2023. We also searched the PharmGKB website for levels of evidence of variant-drug combinations and for drug labels and clinical guidelines. We focus on the pharmacogenetics of novel antiplatelets and anticoagulants while excluding acetylsalicylic acid, warfarin and heparins, and discuss the current knowledge with emphasis on the level of evidence.

Advances and Perspectives in methods for identifying high platelet reactivity

Antiplatelet therapy is the foundational treatment for the prevention and treatment of coronary and cerebrovascular ischemic events in patients with coronary heart disease, ischemic stroke, and transient ischemic attack (TIA). However, with more and more studies reporting an increased risk of thrombosis in some patients due to poor response to therapeutic agents, the selection of appropriate P2Y12 inhibitors has become a major challenge that needs to be addressed urgently. Currently, commonly used oral P2Y12 inhibitors include clopidogrel, ticagrelor, and prasugrel. Assessing patients' risk factors before the development of treatment regimens by effectively predicting the risk of high platelet reactivity with specific P2Y12 inhibitors in advance to avert the occurrence of major adverse cardiovascular and cerebrovascular events (MACCE) is the key point to the problem. Up to now, methods available for predicting platelet reactivity include genetic testing, platelet function testing, and risk scores. This review provides a summarization of the existent available identification methods and analyzes the advantages and drawbacks of different methods in specific clinical settings, intending to guide the rational clinical application of P2Y12 receptor inhibitors.

Platelets and the Atherosclerotic Process: An Overview of New Markers of Platelet Activation and Reactivity, and Their Implications in Primary and Secondary Prevention

The key role played by platelets in the atherosclerosis physiopathology, especially in the acute setting, is ascertained: they are the main actors during thrombus formation and, thus, one of the major investigated elements related to atherothrombotic process involving coronary arteries. Platelets have been studied from different points of view, according with the technology advances and the improvement in the hemostasis knowledge achieved in the last years. Morphology and reactivity constitute the first aspects investigated related to platelets with a significant body of evidence published linking a number of their values and markers to coronary artery disease and cardiovascular events. Recently, the impact of genetics on platelet activation has been explored with promising findings as additional instrument for patient risk stratification; however, this deserves further confirmations. Moreover, the interplay between immune system and platelets has been partially elucidated in the last years, providing intriguing elements that will be basic components for future research to better understand platelet regulation and improve cardiovascular outcome of patients.

New Insights into Pathophysiology and New Risk Factors for ACS

Cardiovascular disease still represents the main cause of mortality worldwide. Despite huge improvements, atherosclerosis persists as the principal pathological condition, both in stable and acute presentation. Specifically, acute coronary syndromes have received substantial research and clinical attention in recent years, contributing to improve overall patients' outcome. The identification of different evolution patterns of the atherosclerotic plaque and coronary artery disease has suggested the potential need of different treatment approaches, according to the mechanisms and molecular elements involved. In addition to traditional risk factors, the finer portrayal of other metabolic and lipid-related mediators has led to higher and deep knowledge of atherosclerosis, providing potential new targets for clinical management of the patients. Finally, the impressive advances in genetics and non-coding RNAs have opened a wide field of research both on pathophysiology and the therapeutic side that are extensively under investigation.

Ticagrelor Resistance in Cardiovascular Disease and Ischemic Stroke

Ticagrelor, acting as a reversible platelet aggregation inhibitor of P2Y12 receptors (P2Y12R), is regarded as one of the first-line antiplatelet drugs for acute cardiovascular diseases. Though the probability of ticagrelor resistance is much lower than that of clopidogrel, there have been recent reports of ticagrelor resistance. In this review, we summarized the clinical application of ticagrelor and then presented the criteria and current status of ticagrelor resistance. We further discussed the potential mechanisms for ticagrelor resistance in terms of drug absorption, metabolism, and receptor action. In conclusion, the incidences of ticagrelor resistance fluctuated between 0 and 20%, and possible mechanisms mainly arose from its absorption and receptor action. Specifically, a variety of factors, such as the drug form of ticagrelor, gut microecology, and the expression and function of P-glycoprotein (P-gp) and P2Y12R, have been shown to be associated with ticagrelor resistance. The exact mechanisms of ticagrelor resistance warrant further exploration, which may contribute to the diagnosis and treatment of ticagrelor resistance.

Gut microbiota induces high platelet response in patients with ST segment elevation myocardial infarction after ticagrelor treatment

Background:

Ticagrelor is a first-line drug for the treatment of acute ST elevation myocardial infarction (STEMI). However, approximately 20% STEMI patients taking ticagrelor exhibited a delayed response and the mechanism was still unclear.

Methods:

To explore the mechanism of the poor response of ticagrelor in post-percutaneous coronary intervention (PCI) patients, we enrolled 65 high platelet reactivity (HPR) patients and 90 controls (normal platelet reactivity [NPR]). Pharmacokinetic assessment result showed that the plasma concentrations of ticagrelor and its metabolism production, AR-C124910XX, were lower in HPR patients than controls. Further single nucloetide polymorphism (SNP) analysis identified that there is no difference in ATP binding cassette subfamily B member 1 (ABCB1) gene expression between the NPR group and the HPR group. Metagenomic and metabolomic analyses of fecal samples showed that HPR patients had higher microbial richness and diversity. Transplantation of the gut microbiota from HPR donors to microbiota-depleted mice obviously decreased plasma concentration of ticagrelor.

Results:

Our findings highlight that gut microbiota dysbiosis may be an important mechanism for the ticagrelor of HPR in patients with STEMI and support that modify gut microbiota is a potential therapeutic option for STEMI.

Conclusions:

Our findings highlight that gut microbiota dysbiosis may be an important mechanism for the ticagrelor of HPR in patients with ST elevation myocardial infarction (STEMI) and support that modify gut microbiota is a potential therapeutic option for STEMI

Funding:

NSFC 82170297 and 82070300 from the National Natural Science Foundation of China.

Identification of Potential Biological Factors Affecting the Treatment of Ticagrelor After Percutaneous Coronary Intervention in the Chinese Population

Background

Generally, many individual factors can affect the clinical application of drugs, of which genetic factors contribute more than 20%. Ticagrelor is a new class of receptor inhibitors receptor antagonist of P2Y12 and is used as an antiplatelet agents. But it is not affected by the influence of CYP2C19 polymorphism. With lack of predicted biomarkers, especially the research data of Chinese, it has the important significance in studying individual differences of ticagrelor in the antiplatelet efficacy and safety, through pharmacogenomics research.

Methods

Whole-exome sequencing (WES) was performed in 100 patients after PCI with ticagrelor treatment. Clinical characteristics and WES of patients were used to performed genome-wide association analysis (GWAS), region-based tests of rare DNA variant to find the influencing factors of antiplatelet effect to ticagrelor and bleeding events. Co-expression, protein–protein interaction (PPI) network and pathway enrichment analysis were then used to find possible genetic mechanisms. Atlas of GWAS (https://atlas.ctglab.nl/) were used for external data validation.

Results

DNAH17, PGS1 and ABCA1 as the potential variant genes are associated with the expected antiplatelet effect to ticagrelor. The affected pathways may include the synthesis and metabolism of lipoprotein cholesterol and the catabolic process of pyrimidine-containing compound (GO:0072529). Age, sex and PLT were found may be potential factors for ticagrelor bleeding events.

Conclusion

We systematically identified new genetic variants and some risk factors for reduced efficacy of ticagrelor and highlighted related genes that may be involved in antiplatelet effects and bleeding event of ticagrelor. Our results enhance the understanding of the absorption and metabolic mechanisms that influence antiplatelet response to ticagrelor treatment.

Trial Registration

ClinicalTrials.gov Identifier: NCT03161002. First Posted: May 19, 2017. https://clinicaltrials.gov/ct2/show/study/NCT03161002.

Ticagrelor and prasugrel in acute coronary syndrome: a single-arm crossover platelet reactivity study

AIM

To compare the degree of platelet inhibition between ticagrelor and prasugrel in patients undergoing percutaneous coronary intervention for acute coronary syndrome.

METHODS

Platelet function was assessed by impedance aggregometry after 30-90 days of therapy with acetylsalicylic acid and ticagrelor and over 15 days after switching to prasugrel. High-on-treatment platelet reactivity (HRPR) was defined for ADP test results above the upper limit of normal.

RESULTS

A total of 105 patients were included, 81.9% males and 33.3% people with diabetes, with a mean age of 60.8 ± 8.1 years. Mean platelet reactivity was not significantly different between the two antiplatelet strategies, as the prevalence of HRPR (8.6 vs 12.3%, P = 0.50). Switching between the two antiplatelet agents was safe and well tolerated, and effectively reduced platelet reactivity in over 95% of the patients (only 3.8% of the study population displaying ineffective response to both drugs).

CONCLUSION

Ticagrelor and prasugrel have a similar effect on platelet reactivity. Switching between the two drugs can be safely done.

Ticagrelor resistance: a case series and algorithm for management of non-responders

The placement of cervical and intracranial stents requires the administration of antiplatelet drugs to prevent thromboembolic complications. Ticagrelor has emerged as the most widely used alternative in clopidogrel non-responders owing to its potent antiplatelet effects. Because ticagrelor does not require hepatic activation, many neurointerventionalists choose to forgo laboratory testing of platelet inhibition. In rare instances, patients may not achieve adequate platelet inhibition following ticagrelor administration. In this paper we review the mechanism of action of ticagrelor and its use in cerebrovascular procedures. We present two cases of ticagrelor non-responsiveness from two high-volume cerebrovascular centers, discuss their management, and propose an algorithm for managing ticagrelor non-responsiveness.

Role of Cardiac A2A Receptors Under Normal and Pathophysiological Conditions

This review presents an overview of cardiac A2A-adenosine receptors The localization of A2A-AR in the various cell types that encompass the heart and the role they play in force regulation in various mammalian species are depicted. The putative signal transduction systems of A2A-AR in cells in the living heart, as well as the known interactions of A2A-AR with membrane-bound receptors, will be addressed. The possible role that the receptors play in some relevant cardiac pathologies, such as persistent or transient ischemia, hypoxia, sepsis, hypertension, cardiac hypertrophy, and arrhythmias, will be reviewed. Moreover, the cardiac utility of A2A-AR as therapeutic targets for agonistic and antagonistic drugs will be discussed. Gaps in our knowledge about the cardiac function of A2A-AR and future research needs will be identified and formulated.

Impact of the Polymorphism rs5751876 of the Purinergic Receptor ADORA2A on Periprocedural Myocardial Infarction in Patients Undergoing Percutaneous Coronary Intervention

Aim: Periprocedural myocardial infarction (PMI), a severe complication of Percutaneous Coronary Intervention (PCI) procedures, has a negative prognostic effect, both at short and long-term follow-up. So far, adenosine's role in preventing PMI has shown contrasting results. A genetic variant of ADORA2A receptor, 1976 C > T, has been suggested as a potential determinant of the interindividual response to adenosine, thus conditioning its potential benefits on PMI. In our study, we investigated whether the ADORA2A 1976 C > T polymorphism is associated with PMI occurrence in patients undergoing coronary stenting.

Methods: The study included consecutive patients undergoing PCI at the Azienda Ospedaliera-Universitaria “Maggiore della Carità,” Novara, Italy, between January 2010 and January 2016. Their genetic status was assessed using polymerase chain reaction (PCR) and restriction-fragment-length-polymorphism technique. Myonecrosis biomarkers were measured at intervals from 6 to 48 hours. PMI was defined as CKMB increased 3 times over the Upper Limit of Normal (ULN), or 50% of pre-PCI value; periprocedural myonecrosis was defined as troponin I increased 3 times over the ULN or by 50% of the baseline value.

Results: We included 1,104 patients undergoing PCI, 863 (78.2%) of whom carried the ADORA2A T-allele. No difference was found for the main demographic, clinical features, or biochemistry parameters. However, C-carriers had lower statin therapy use (p = 0.008) and lower HDL-cholesterol levels (p = 0.01). Homozygous C/C patients had more frequent multivessel disease (p = 0.03), longer lesions (p = 0.01) and Type C lesions (p = 0.01), thus requiring more complex procedures. After correction for baseline confounding factors at multivariate analysis, there was no difference in myocardial necrosis according to the ADORA2A genotype (p = 0.40). In contrast, PMI tended to increase in the homozygous C/C population (p = 0.06), but this trend was attenuated at multivariate analysis after correction for baseline confounding factors (C/C: OR[95%CI]= 1.52 [0.88–2.6], p = 0.14).

Conclusions: Our study showed that the polymorphism rs5751876 of the ADORA2A receptor is associated with a higher prevalence of complex coronary lesions and multivessel disease. However, it does not significantly influence the occurrence of periprocedural MI or myonecrosis.

Impact of the rs73598374 polymorphism of the adenosine deaminase gene on platelet reactivity and long-term outcomes among patients with acute coronary syndrome treated with ticagrelor

BACKGROUND

The positive interaction of ticagrelor with the metabolism of adenosine has been claimed for the large antithrombotic and antiischemic benefits of this antiplatelet agent in acute coronary syndromes (ACS). Adenosine catabolism is regulated by the activity of the adenosine deaminase enzyme (ADA), for which several polymorphisms have been identified. Therefore, the aim of our study was to explore the impact of the rs73598374 polymorphism of ADA gene on platelet reactivity in ACS patients treated with ticagrelor.

METHODS

We included consecutive patients receiving ASA and ticagrelor after an ACS and coronary intervention. Platelet reactivity was evaluated by impedance aggregometry at 30-90 days post-discharge. The genetic analysis was carried out by PCR and RFLP. Clinical endpoints were mortality, cardiovascular death, recurrent myocardial infarction or coronary revascularization at the maximum available follow-up.

RESULTS

Our population is represented by 464 patients, of whom 33.4% were A-heterozygotes and 6 homozygotes. A-allele carriers showed a greater prevalence of renal failure (p = 0.02) and a lower rate of previous coronary artery bypass graft (p = 0.03) and statin treatment (p = 0.02). No differences in the mean values of platelet reactivity or HRPR on ticagrelor were found according to the ADA genotype (11.3%vs13.9%, p = 0.45; adjusted OR[95% CI] = 1.17[0.64-2.14], p = 0.61). At follow up, patients carrying the A-allele showed a non-significantly lower incidence of ACS and repeated unplanned revascularization, although with no effect on mortality.

CONCLUSIONS

In the present study the rs73598374 polymorphism of the ADA gene did not affect platelet reactivity or the long-term prognosis in patients with ACS receiving dual antiplatelet therapy with ASA and ticagrelor.

Analysis of association of ADORA2A and ADORA3 polymorphisms genotypes/haplotypes with efficacy and toxicity of methotrexate in patients with Rheumatoid arthritis

Adenosine receptors ADORA₂A and ADORA₃ are part of the adenosine-mediated antiinflammatory pathway and are overexpressed in patients with Rheumatoid arthritis (RA). Methotrexate (MTX) antiinflammatory effects are partially mediated via increased release of adenosine into extracellular space. Polymorphisms in ADORA₂A and ADORA₃ genes may have an impact on the efficacy and toxicity of MTX in RA patients. The study included 127 RA patients. Treatment efficacy was estimated using the changes in Disease activity score (DAS28) after 6 months of MTX monotherapy, according to EULAR response criteria. Patients with good and moderate response were classified as "responders", and with a poor response as "nonresponders". Adverse effects were collected during the follow-up period. Genotyping for polymorphisms within ADORA₂A gene (rs2298383, rs2236624, rs5751876, rs17004921) and ADORA₃ gene (rs2298191, rs1544223, rs3393) was performed using the KASPar assays. Among patients 112 (88.19%) were responders (18.8% good, 81.2% moderate). We observed no association between analyzed genotypes or alleles and MTX response by EULAR criteria but carriers of ADORA₂A rs17004921 T allele (CT + TT) had a higher DAS28 decrease after 6 months of treatment than patients with CC genotype (p = 0.013). Adverse effects were reported in 31 patients (24.41%). Bone erosions were present in 82 (64.6%) patients. Haplotype block was observed among all 3 analyzed polymorphisms within ADORA₃ gene and TAA haplotype was associated with bone erosions (29% vs 15.6%, p = 0.023) and hepatotoxicity (51.3% vs 21.6%, p = 0.013). According to our study, ADORA₃ TAA haplotype may be associated with bone erosions and hepatotoxicity in RA patients treated with MTX.

Relationship between adenosine A2a receptor polymorphism rs5751876 and fractional flow reserve during percutaneous coronary intervention

Fractional flow reserve (FFR) assessed during adenosine-induced maximal hyperemia has emerged as a useful tool for the guidance of percutaneous coronary interventions (PCI). However, interindividual variability in the response to adenosine has been claimed as a major limitation to the use of adenosine for the measurement of FFR, carrying the risk of underestimating the severity of coronary stenoses, with potential negative prognostic consequences. Genetic variants of the adenosine receptor A2a (ADORA2A gene), located in the coronary circulation, have been involved in the modulation of the hyperemic response to adenosine. However, no study has so far evaluated the impact of the single nucleotide polymorphism rs5751876 of ADORA2A on the measurement of FFR in patients undergoing percutaneous coronary intervention that was, therefore, the aim of our study. We included patients undergoing coronary angiography and FFR assessment for intermediate (40-70%) coronary lesions. FFR measurement was performed by pressure-recording guidewire (Prime Wire, Volcano), after induction of hyperemia with intracoronary boli of adenosine (from 60 to 1440 μg, with dose doubling at each step). Restriction fragment length polymorphism (RFLP) analysis was performed to assess the presence of rs5751876 C>T polymorphism of ADORA2a receptor. We included 204 patients undergoing FFR measurement of 231 coronary lesions. A total of 134 patients carried the polymorphism (T allele), of whom 41 (30.6%) in homozygosis (T/T).Main clinical and angiographic features did not differ according to ADORA2A genotype. The rs5751876 C>T polymorphism did not affect mean FFR values (p = 0.91), the percentage of positive FFR (p = 0.54) and the duration of maximal hyperemia. However, the time to recovery to baseline FFR values was more prolonged among the T-allele carriers as compared to wild-type patients (p = 0.04). Based on these results, in patients with intermediate coronary stenoses undergoing FFR assessment with adenosine, the polymorphism rs5751876 of ADORA2A does not affect the peak hyperemic response to adenosine and the results of FFR. However, a more prolonged effect of adenosine was observed in T-carriers.

Ticagrelor in the prevention of coronary and non-coronary atherothrombotic events: A comprehensive meta-analysis of 10 randomized trials

BACKGROUND AND AIMS

More potent antithrombotic strategies have significantly reduced the rate of recurrent ischemic events in cardiovascular disease. Ticagrelor, in particular, has significantly improved the outcome in patients with acute coronary syndromes, offering potential benefits also in terms of survival. In addition, more recent data have suggested that the advantages of ticagrelor could be extended also to non-coronary atherothrombotic disease, although with contrasting results, especially for mortality reduction. The aim of the present meta-analysis was to investigate the safety and effectiveness of a newer antiplatelet strategy with ticagrelor as compared to traditional antiplatelet regimens in patients with coronary or non-coronary atherothrombotic disease.

METHODS

Literature and main scientific session abstracts were searched for studies comparing a ticagrelor-based antiplatelet regimen vs. different antiplatelet agents in the secondary prevention of cardiac, cerebral or vascular atherothrombotic events. The primary efficacy endpoint was mortality, primary safety endpoint was the occurrence of major bleedings. Secondary endpoints were myocardial infarction and stroke.

RESULTS

We included 10 randomized clinical trials, for a total population of 73,121 patients, 54.9% randomized to ticagrelor. At a mean follow-up of 13.4 ± 12.6 months, a newer antiplatelet strategy based on ticagrelor was associated with a significant reduction in mortality as compared to a traditional therapy (OR[95%CI] = 0.92[0.86,0.99], p=0.02; phet = 0.14), however, such benefits were more evident in patients with coronary artery disease, while not in non-coronary trials, with a significant interaction between patients' setting and the prognostic impact of ticagrelor (p int = 0.03). A similar result was achieved for cardiovascular mortality, recurrent myocardial infarction, while for the risk of stroke, the largest advantages were observed in patients with a previous cerebrovascular accident. Major bleeding events were increased in ticagrelor treated patients (OR [95%CI] = 1.11 [1.02, 1.20], p=0.01; phet = 0.0003), although not affecting overall mortality, as confirmed by meta-regression analysis.

CONCLUSIONS

Based on the current meta-analysis, a newer antiplatelet strategy based on ticagrelor is associated with a significant reduction in mortality and recurrent cardiovascular events, as compared to a traditional treatment, among patients treated for coronary disease but not among those with non-coronary atherothrombotic disease. However, ticagrelor therapy was associated with a significant increase in major bleeding complications.