Pharmacodynamics, pharmacokinetics, and safety of the oral reversible P2Y12 antagonist AZD6140 with aspirin in patients with atherosclerosis: a double-blind comparison to clopidogrel with aspirin

Viewpoint: Reversible nature of platelet binding causing transfusion-related acute lung injury (TRALI) syndrome may explain dyspnea after ticagrelor and elinogrel

There may be a universal mechanism explaining dyspnea after ticagrelor and elinogrel, namely, transfusion-related acute lung injury (TRALI). Indeed, recent clinical trials with ticagrelor (DISPERSE, DISPERSE-II, and PLATO), and elinogrel (INNOVATE PCI) revealed double-digit rates of dyspnea after novel reversible antiplatelet agents. In contrast, dyspnea is not associated with conventional non-reversible agents such as aspirin, or thienopyridines (ticlopidine, clopidogrel, or prasugrel) suggesting distinct mechanism of shortness of breath after ticagrelor and elinogrel. The adenosine hypothesis has been offered to explain such adverse association. However, despite obvious similarity between ticagrelor and adenosine molecules, the chemical structure of elinogrel is entirely different. In fact, ticagrelor is a cyclopentyl-triazolo-pyrimidine, while elinogrel is a quinazolinedione. Since both agents cause dyspnea, the adenosine hypothesis is no longer valid. In contrast, the reversible nature of platelet inhibition attributable to both ticagrelor and elinogrel causing premature cell ageing, apoptosis, impaired turnover due to sequestration of overloaded, exhausted platelets in the pulmonary circulation are among potential autoimmune mechanism(s) resulting in the development of a TRALI-like reaction, and frequent dyspnea. Despite expected benefit for better bleeding control, further development of reversible antithrombins is severely limited due to the existence of a potentially universal serious adverse event, such as TRALI-syndrome with dyspnea as a predominant clinical manifestation. Since TRALI is an established number one contributor to mortality after blood transfusions, ticagrelor death “benefit”in PLATO is challenged further.

Assessment of bleeding risk in patients with coronary artery disease on dual antiplatelet therapy

Patients with coronary artery disease are usually treated with dual antiplatelet therapy (DAPT) after percutaneous coronary intervention. Patients on DAPT are at risk of both ischaemic and bleeding events. Although side-lined for a long time, real-life studies have shown that both the incidence and the associated morbidity and mortality of outof-hospital bleeding are high. This indicates that prevention of (postinterventional) bleeding is as important as prevention of ischaemia. For this purpose it is crucial to reliably identify patients with a high bleeding risk. In order to postulate an algorithm, which could help identifying these patients, we performed a systematic review to determine the value of previously proposed prognostic modalities for bleeding. We searched and appraised the following tools: platelet function tests, genetic tests, bleeding scores and questionnaires and haemostatic tests. Most studies indicated that low on-treatment platelet reactivity (LTPR), as measured by several platelet function tests, and the carriage of CYP2C19*17 allele were independent risk factors for bleeding. A bleeding score also proved to be helpful in identifying patients at risk. No studies on haemostatic tests were retrieved. Several patient characteristics were also identified as independent predictors of bleeding, such as older age, female sex and renal failure. Combining these risk factors we propose an algorithm that would hypothetically facilitate identification of those patients at highest risk, warranting prevention measures for bleeding. This could be a starting point for further research concerning the topic.

Cardiovascular and Bleeding Risks in Acute Myocardial Infarction Newly Treated With Ticagrelor vs. Clopidogrel in Taiwan

BACKGROUND

There are few data on ticagrelor in Asian patients. This study evaluated clinical outcomes with ticagrelor and clopidogrel in Taiwanese patients with acute myocardial infarction (AMI).Methods and Results:We used the Taiwan National Health Insurance Research Database to identify 27,339 AMI patients aged ≥18 years between January 2012 and December 2014, and only patients who survived greater than or equal to 30 days after AMI and took dual antiplatelet therapy were included. Cohorts of ticagrelor and clopidogrel were matched 1:8, based on propensity score matching, to balance baseline covariates. The primary efficacy endpoints were death from any cause, AMI, or stroke. The safety endpoints consisted of major gastrointestinal bleeding or intracerebral hemorrhage. Following propensity matching, the primary efficacy endpoint rate was 22% lower in the ticagrelor group than in the clopidogrel group (10.6% and 16.2%, respectively; adjusted HR, 0.779; 95% CI: 0.684-0.887). The safety endpoint rate was similar between the ticagrelor and clopidogrel groups (3.2% and 4.1% respectively; adjusted HR, 0.731; 95% CI: 0.522-1.026).

CONCLUSIONS

In real-world AMI Taiwanese patients, ticagrelor seemed to offer better anti-ischemic protection than clopidogrel, without an increase in the rate of major bleeding. A large-scale randomized trial is needed to assess the efficacy and safety of ticagrelor in East Asian AMI patients.

Comparison of bioavailability and antiplatelet action of ticagrelor in patients with ST-elevation myocardial infarction and non-ST-elevation myocardial infarction: A prospective, observational, single-centre study

BACKGROUND

Data from available studies suggest that the presence of ST-elevation myocardial infarction (STEMI) may be associated with delayed and attenuated ticagrelor bioavailability and effect compared with non-ST-elevation myocardial infarction (NSTEMI).

METHODS

In a single-center, prospective, observational trial 73 patients with myocardial infarction (STEMI n = 49, NSTEMI n = 24) underwent a pharmacokinetic and pharmacodynamic assessment after a 180 mg ticagrelor loading dose (LD). Ticagrelor and its active metabolite (AR-C124910XX) plasma concentrations were determined with liquid chromatography tandem mass spectrometry, and their antiplatelet effect was measured with the VASP assay and multiple electrode aggregometry.

RESULTS

During the first six hours after ticagrelor LD, STEMI patients had 38% and 34% lower plasma concentration of ticagrelor and AR-C124910XX, respectively, than NSTEMI (ticagrelor AUC(0-6): 2491 [344-5587] vs. 3991 [1406-9284] ng*h/mL; p = 0.038; AR-C124910XX AUC(0-6): 473 [0-924] vs. 712 [346-1616] ng*h/mL; p = 0.027). STEMI patients also required more time to achieve maximal concentration of ticagrelor (tmax: 4.0 [3.0-12.0] vs. 2.5 [2.0-6.0] h; p = 0.012). Impaired bioavailability of ticagrelor and AR-C124910XX seen in STEMI subjects was associated with diminished platelet inhibition in this group, which was most pronounced during the initial hours of treatment.

CONCLUSIONS

Plasma concentrations of ticagrelor and AR-C124910XX during the first hours after ticagrelor LD were one third lower in STEMI than in NSTEMI patients. This reduced and delayed ticagrelor bioavailability was associated with weaker antiplatelet effect in STEMI.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02602444 (November 09, 2015).

Role of P2Y12 Receptor in Thrombosis

P2Y₁₂ receptor is a 342 amino acid Gi-coupled receptor predominantly expressed on platelets. P2Y₁₂ receptor is physiologically activated by ADP and inhibits adenyl cyclase (AC) to decrease cyclic AMP (cAMP) level, resulting in platelet aggregation. It also activates PI3 kinase (PI3K) pathway leading to fibrinogen receptor activation, and may protect platelets from apoptosis. Abnormalities of P2Y₁₂ receptor include congenital deficiencies or high activity in diseases like diabetes mellitus (DM) and chronic kidney disease (CKD), exposing such patients to a prothrombotic condition. A series of clinical antiplatelet drugs, such as clopidogrel and ticagrelor, are designed as indirect or direct antagonists of P2Y₁₂ receptor to reduce incidence of thrombosis mainly for patients of acute coronary syndrome (ACS) who are at high risk of thrombotic events. Studies on novel dual-/multi-target antiplatelet agents consider P2Y₁₂ receptor as a promising part in combined targets. However, the clinical practical phenomena, such as "clopidogrel resistance" due to gene variations of cytochrome P450 or P2Y₁₂ receptor constitutive activation, call for better antiplatelet agents. Researches also showed inverse agonist of P2Y₁₂ receptor could play a better role over neutral antagonists. Personalized antiplatelet therapy is the most ideal destination for antiplatelet therapy in ACS patients with or without other underlying diseases like DM or CKD, however, there is still a long way to go.

Risk for Major Bleeding in Patients Receiving Ticagrelor Compared With Aspirin After Transient Ischemic Attack or Acute Ischemic Stroke in the SOCRATES Study (Acute Stroke or Transient Ischemic Attack Treated With Aspirin or Ticagrelor and Patient Outcomes)

Background:

Patients with minor acute ischemic stroke or transient ischemic attack are at high risk for subsequent stroke, and more potent antiplatelet therapy in the acute setting is needed. However, the potential benefit of more intense antiplatelet therapy must be assessed in relation to the risk for major bleeding. The SOCRATES trial (Acute Stroke or Transient Ischemic Attack Treated With Aspirin or Ticagrelor and Patient Outcomes) was the first trial with ticagrelor in patients with acute ischemic stroke or transient ischemic attack in which the efficacy and safety of ticagrelor were compared with those of aspirin. The main safety objective was assessment of PLATO (Platelet Inhibition and Patient Outcomes)–defined major bleeds on treatment, with special focus on intracranial hemorrhage (ICrH).

Methods:

An independent adjudication committee blinded to study treatment classified bleeds according to the PLATO, TIMI (Thrombolysis in Myocardial Infarction), and GUSTO (Global Use of Strategies to Open Occluded Coronary Arteries) definitions. The definitions of ICrH and major bleeding excluded cerebral microbleeds and asymptomatic hemorrhagic transformations of cerebral infarctions so that the definitions better discriminated important events in the acute stroke population.

Results:

A total of 13 130 of 13 199 randomized patients received at least 1 dose of study drug and were included in the safety analysis set. PLATO major bleeds occurred in 31 patients (0.5%) on ticagrelor and 38 patients (0.6%) on aspirin (hazard ratio, 0.83; 95% confidence interval, 0.52–1.34). The most common locations of major bleeds were intracranial and gastrointestinal. ICrH was reported in 12 patients (0.2%) on ticagrelor and 18 patients (0.3%) on aspirin. Thirteen of all 30 ICrHs (4 on ticagrelor and 9 on aspirin) were hemorrhagic strokes, and 4 (2 in each group) were symptomatic hemorrhagic transformations of brain infarctions. The ICrHs were spontaneous in 6 and 13, traumatic in 3 and 3, and procedural in 3 and 2 patients on ticagrelor and aspirin, respectively. In total, 9 fatal bleeds occurred on ticagrelor and 4 on aspirin. The composite of ICrH or fatal bleeding included 15 patients on ticagrelor and 18 on aspirin. Independently of bleeding classification, PLATO, TIMI, or GUSTO, the relative difference between treatments for major/severe bleeds was similar. Nonmajor bleeds were more common on ticagrelor.

Conclusions:

Antiplatelet therapy with ticagrelor in patients with acute ischemic stroke or transient ischemic attack showed a bleeding profile similar to that of aspirin for major bleeds. There were few ICrHs.

Clinical Trial Registration:

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01994720.

The reversible P2Y12 antagonist ACT-246475 causes significantly less blood loss than ticagrelor at equivalent antithrombotic efficacy in rat

The P2Y₁₂ receptor is a validated target for prevention of major adverse cardiovascular events in patients with acute coronary syndrome. The aim of this study was to compare two direct-acting, reversible P2Y₁₂ antagonists, ACT-246475 and ticagrelor, in a rat thrombosis model by simultaneous quantification of their antithrombotic efficacy and surgery-induced blood loss. Blood flow velocity was assessed in the carotid artery after FeCl₃ -induced thrombus formation using a Doppler flow probe. At the same time, blood loss after surgical wounding of the spleen was quantified. Continuous infusions of ACT-246475 and ticagrelor prevented the injury-induced reduction of blood flow in a dose-dependent manner. High doses of both antagonists normalized blood flow and completely abolished thrombus formation as confirmed by histology. Intermediate doses restored baseline blood flow to ≥65%. However, ACT-246475 caused significantly less increase of blood loss than ticagrelor; the difference in blood loss was 2.6-fold (P < 0.01) at high doses and 2.7-fold (P < 0.05) at intermediate doses. Potential reasons for this unexpected difference were explored by measuring the effects of ACT-246475 and ticagrelor on vascular tone. At concentrations needed to achieve maximal antithrombotic efficacy, ticagrelor compared with ACT-246475 significantly increased carotid blood flow velocity in vivo (P = 0.003), induced vasorelaxation of precontracted rat femoral arteries, and inhibited contraction of femoral artery induced by electrical field stimulation or by phenylephrine. Overall, ACT-246475 showed a significantly wider therapeutic window than ticagrelor. The absence of vasodilatory effects due to high selectivity of ACT-246475 for P2Y₁₂ provides potential arguments for the observed safety advantage of ACT-246475 over ticagrelor.

Management of antithrombotic agents in patients undergoing flexible bronchoscopy

Bleeding is one of the most feared complications of flexible bronchoscopy. Although infrequent, it can be catastrophic and result in fatal outcomes. Compared to other endoscopic procedures, the risk of morbidity and mortality from the bleeding is increased, as even a small amount of blood can fill the tracheobronchial tree and lead to respiratory failure. Patients using antithrombotic agents (ATAs) have higher bleeding risk. A thorough understanding of the different ATAs is critical to manage patients during the peri-procedural period. A decision to stop an ATA before bronchoscopy should take into account a variety of factors, including indication for its use and the type of procedure. This article serves as a detailed review on the different ATAs, their pharmacokinetics and the pre- and post-bronchoscopy management of patients receiving these medications.

Comparison of the Antiplatelet Effects of Once and Twice Daily Low-Dose Ticagrelor and Clopidogrel After Percutaneous Coronary Intervention

Although Asian people are believed to be more susceptible to bleeding on currently recommended dose of ticagrelor, there is limited evidence supporting low-dose ticagrelor. We prospectively randomized patients receiving dual antiplatelet therapy with aspirin and clopidogrel into 3 groups; aspirin plus clopidogrel 75 mg versus aspirin plus ticagrelor 90 mg once daily versus aspirin plus ticagrelor 45 mg twice daily. Platelet function assessments were conducted using VerifyNow P2Y12 assay at baseline and 28 days after randomization. No differences in baseline P2Y12 reaction unit (PRU) values were observed among the 3 groups. PRU values at the end of the treatment periods were significantly lower in low-dose ticagrelor (90 mg QD group, 98.6 ± 73.4 and 45 mg BID group, 65.5 ± 58.8) compared with clopidogrel (221.2 ± 50.1, both p <0.001). There was no significant difference in PRU values between 2 groups of low-dose ticagrelor (p = 0.208). The rates of high on-treatment platelet reactivity were significantly lower in low-dose ticagrelor compared with clopidogrel, whereas clopidogrel showed higher rate of optimal on-treatment platelet reactivity than ticagrelor 45 mg BID. However, similar rate of optimal on-treatment platelet reactivity was observed in clopidogrel and ticagrelor 90 mg QD. In conclusion, low-dose ticagrelor treatment, either with 90 mg QD or 45 mg BID, was associated with a more potent antiplatelet effect compared with clopidogrel treatment and once daily dose provided similar antiplatelet effect but favorable effect on optimal platelet inhibition compared with twice daily dose.

Reversal of the platelet inhibitory effect of the P2Y12 inhibitors clopidogrel, prasugrel, and ticagrelor in vitro: a new approach to an old issue

AIM

Platelet transfusion is an effective option to reverse platelet inhibition in thienopyridine-treated patients suffering from bleedings or requiring urgent surgery. However, in ticagrelor-treated patients, the previous studies revealed significant clinical effects to platelet rich plasma (PRP) but poor response to pooled platelets (PP) as used in clinical routine. The aim of this study was to elucidate a potential pathomechanism to explain the poor response of ticagrelor to PP.

METHODS AND RESULTS

From 79 whole blood samples of patients treated with ticagrelor, prasugrel, or clopidogrel, the PRI-VASP was determined before and after in vitro platelet supplementation of PP or PRP at increasing concentrations. Compared to prasugrel- and clopidogrel-treated patients, the PRI-VASP of ticagrelor-treated patients showed no significant increase after in vitro administration of PP. PRI-VASP was performed in ticagrelor-treated samples after in vitro addition of 1: centrifuged PRP platelets resuspended in PP buffer, 2: PP with human serum, 3: human serum alone. Surprisingly, PP with human serum or human serum alone were able to significantly increase PRI-VASP in samples of ticagrelor-treated patients (11.7 ± 10.9 → 61.3 ± 10.9%, p = 0.006; 11.7 ± 10.9 → 54.1 ± 2.7%, p < 0.001). This effect could also be shown using human albumin (18.9 ± 5.1% → 80 g/l human albumin: 48.1 ± 8.3%, p < 0.001).

CONCLUSION

The present study demonstrates that addition of human serum and human albumin alone is able to reverse the ticagrelor effects in vitro and supports our novel hypothesis of the importance of proteins in reversing the effects of ticagrelor by binding active ticagrelor.

The progress in the research of antiplatelet agents (1995-2017)

Antiplatelet therapy displays a critical role in the treatment and prevention of antithrombotic disorders. Many new antiplatelet agents have been developed following the emergence of various clinical limitations of classical antiplatelet drugs. This review covers mainly the recent advances in the development of P2Y₁₂ antagonists and GPIIb/IIIa antagonists. Meanwhile, it summarizes promising approaches to new platelet surface receptors such as prostanoid EP3 receptor, thromboxane A₂ prostanoid receptor, protease-activated receptors, GPIb-IX-V receptor and P-selectin. In addition, PI3K_β, a critical protein at the inside signaling pathway of platelet activation is also mentioned as an important antiplatelet target. Moreover, the development of respective drug candidates is discussed in detail.

Antithrombotic therapy for acute coronary syndrome: Past, present and future

Plaque erosions and ruptures are the histopathological hallmarks of arterial thrombus formation in the coronary arteries. The clinical condition associated with this process is usually referred to as acute coronary syndrome (ACS). Importantly, both blood platelets and the coagulation cascade are key players for initiation, amplification and perpetuation of ACS. There has been great progress in ACS treatment in recent decades, both at the technical level of (percutaneous) revascularisation and at the level of antithrombotic treatment. Numerous trials have led to significant advancements in the development of effective anticoagulant and antiplatelet drugs. The large number of randomised controlled clinical trials (RCTs) and the huge number of patients enrolled in these RCTs, with mega trials including >10,000 patients, is unique in the history of medical research and also reflects the exceptional efforts associated with these huge research activities. The crucial issue, however, with respect to optimising treatment, relates to finding the delicate balance between the reduction of thrombotic events by effective drug treatment and the induction of bleeding that is linked to the use of potent or multiple antithrombotic agents. Interestingly, there is a gap in modern days between current guideline recommendations favouring potent platelet inhibition in ACS and the utilization of the respective drugs in clinical practice. In this review, we will summarise and discuss the past, present and future antithrombotic treatment for ACS patients with a focus on the development of optimised antiplatelet treatment strategies and their utilisation in the real world.

Clinically significant bleeding with low-dose rivaroxaban versus aspirin, in addition to P2Y12 inhibition, in acute coronary syndromes (GEMINI-ACS-1): a double-blind, multicentre, randomised trial

BACKGROUND

Dual antiplatelet therapy (DAPT), aspirin plus a P2Y12 inhibitor, is the standard antithrombotic treatment following acute coronary syndromes. The factor Xa inhibitor rivaroxaban reduced mortality and ischaemic events when added to DAPT, but caused increased bleeding. The safety of a dual pathway antithrombotic therapy approach combining low-dose rivaroxaban (in place of aspirin) with a P2Y12 inhibitor has not been assesssed in acute coronary syndromes. We aimed to assess rivaroxaban 2·5 mg twice daily versus aspirin 100 mg daily, in addition to clopidogrel or ticagrelor (chosen at investigator discretion before randomisation), for patients with acute coronary syndromes started within 10 days after presentation and continued for 6-12 months.

METHODS

In this double-blind, multicentre, randomised trial (GEMINI-ACS-1) done at 371 clinical centres in 21 countries, eligible patients were older than 18 years with unstable angina, non-ST segment elevation myocardial infarction (NSTEMI) or ST segment elevation myocardial infarction (STEMI), with positive cardiac biomarkers and either ischaemic electrocardiographic changes or an atherosclerotic culprit lesion identified during angiography. Participants were randomly assigned (1:1) within 10 days after admission for the index acute coronary syndromes event to either aspirin or rivaroxaban based on a computer-generated randomisation schedule. Randomisation was balanced by using randomly permuted blocks with size of four and was stratified based on the background P2Y12 inhibitor (clopidogrel or ticagrelor) intended to be used at the time of randomisation. Investigators and patients were masked to treatment assignment. Patients received a minimum of 180 days of double-blind treatment with rivaroxaban 2·5 mg twice daily or aspirin 100 mg daily. The choice of clopidogrel or ticagrelor during trial conduct was not randomised and was based on investigator preference. The primary endpoint was thrombolysis in myocardial infarction (TIMI) clinically significant bleeding not related to coronary artery bypass grafting (CABG; major, minor, or requiring medical attention) up to day 390. Primary analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT02293395.

FINDINGS

Between April 22, 2015, and Oct 14, 2016, 3037 patients with acute coronary syndromes were randomly assigned; 1518 to receive aspirin and 1519 to receive rivaroxaban. 1704 patients (56%) were in the ticagrelor and 1333 (44%) in the clopidogrel strata. Median duration of treatment was 291 days (IQR 239-354). TIMI non-CABG clinically significant bleeding was similar with rivaroxaban versus aspirin therapy (total 154 patients [5%]; 80 participants [5%] of 1519 vs 74 participants [5%] of 1518; HR 1·09 [95% CI 0·80-1·50]; p=0·5840).

INTERPRETATION

A dual pathway antithrombotic therapy approach combining low-dose rivaroxaban with a P2Y12 inhibitor for the treatment of patients with acute coronary syndromes had similar risk of clinically significant bleeding as aspirin and a P2Y12 inhibitor. A larger, adequately powered trial would be required to definitively assess the efficacy and safety of this approach.

FUNDING

Janssen Research & Development and Bayer AG.

Comparison of Ticagrelor Pharmacokinetics and Pharmacodynamics in STEMI and NSTEMI Patients (PINPOINT): protocol for a prospective, observational, single-centre study

INTRODUCTION

The most common classification of acute myocardial infarction (AMI) is based on electrocardiographic findings and distinguishes ST-elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (NSTEMI). Both types of AMI differ concerning their epidemiology, clinical approach and early outcomes. Ticagrelor is a P2Y12 receptor inhibitor, constituting the first-line treatment for STEMI and NSTEMI. According to available data, STEMI may be associated with lower plasma concentration of ticagrelor in the first hours of AMI, but currently there are no studies directly comparing ticagrelor pharmacokinetics or antiplatelet effect in patients with STEMI versus NSTEMI.

METHODS AND ANALYSIS

The PINPOINT study is a phase IV, single-centre, investigator-initiated, prospective, observational study designed to compare the pharmacokinetics and pharmacodynamics of ticagrelor in patients with STEMI and NSTEMI assigned to the invasive strategy of treatment. Based on an internal pilot study, the trial is expected to include at least 23 patients with each AMI type. All subjects will receive a 180 mg loading dose of ticagrelor. The primary end point of the study is the area under the plasma concentration-time curve (AUC_(0-6)) for ticagrelor during the first 6 hours after the loading dose. Secondary end points include various pharmacokinetic features of ticagrelor and its active metabolite (AR-C124910XX), and evaluation of platelet reactivity by the vasodilator-stimulated phosphoprotein assay and multiple electrode aggregometry. Blood samples for the pharmacokinetic and pharmacodynamic assessment will be obtained at pretreatment, 30 min, 1, 2, 3, 4, 6 and 12 hours post-ticagrelor loading dose.

ETHICS AND DISSEMINATION

The study received approval from the Local Ethics Committee (Komisja Bioetyczna Uniwersytetu Mikołaja Kopernika w Toruniu przy Collegium Medicum im. Ludwika Rydygiera w Bydgoszczy; approval reference number KB 617/2015). The study results will be disseminated through conference presentations and peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT02602444; Pre-results.

Novel Anticoagulant Agents in the Perioperative Setting

An increasing number of oral anticoagulants have become available over the past decade. Each of these agents has differing implications on both regional and neuraxial anesthetic techniques. This article describes the pharmacology, pharmacokinetics, and pharmacodynamics of the most commonly used novel oral anticoagulants (NOACs). It also outlines recent guidelines for the use of NOACs in the perioperative setting, especially with regard to neuraxial anesthesia.

Effect of CYP3A4∗1G and CYP3A5∗3 Polymorphisms on Pharmacokinetics and Pharmacodynamics of Ticagrelor in Healthy Chinese Subjects

Ticagrelor is the first reversible, direct-acting, potent P2Y₁₂ receptor antagonist in management of acute coronary syndromes. It is rapidly absorbed and extensively metabolized. AR-C124910XX, the major active metabolite, antagonizes the P2Y₁₂ receptor at approximately equal potency. The metabolism of ticagrelor to AR-C124910XX involves CYP3A4 and CYP3A5. CYP3A polymorphisms have been well documented, and CYP3A4^∗1G (g.20230G>A, rs2242480) and CYP3A5^∗3 (g.6986A>G, rs776746) are the most important single nucleotide polymorphisms in Chinese. Genetic differences in CYP3A4 and CYP3A5 expression in human volunteers and patients might affect the clearance of ticagrelor or AR-C124910XX in vivo resulting in subsequent variable patient response. Thus, this study is designed to explore the effects of CYP3A4^∗1G and CYP3A5^∗3 polymorphisms on the pharmacokinetics and pharmcodynamics of ticagrelor in healthy Chinese subjects. The results indicated that the CYP3A4^∗1G polymorphism significantly influenced the pharmacokinetics of AR-C124910XX, and it may be more important than CYP3A5^∗3 with respect to influencing ticagrelor pharmacokinetics by increasing CYP3A4 activity. However, the significant effect of CYP3A4^∗1G polymorphism on AR-C124910XX plasma levels did not translate into detectable effect on inhibition of platelet aggregation. Therefore, it seems not necessary to adjust the dosage of ticagrelor according to the CYP3A4 or 3A5 genotype.

Single or dual antiplatelet therapy after PCI

The optimal duration and type of antiplatelet therapy after implantation of a drug-eluting stent (DES) remains uncertain. At the time of the first-in-man implantation of the sirolimus DES in 1999, the protocol-defined dual antiplatelet therapy (DAPT) duration was only 2 months. Subsequently, DAPT duration was extended to 1 year on the basis of anecdotal historical data, and this practice was then incorporated into clinical guidelines. For >1 decade, trialists have sought to compare the safety and efficacy of abbreviated (<6 months) and prolonged (>12 months) DAPT regimens. However, the body of evidence is limited by the heterogeneity of end points, time of randomization, and bleeding criteria used in each trial. Pharmaceutical advances led to the introduction of new ADP-receptor antagonists, which are thought to be more effective than clopidogrel. The ADP-receptor antagonists moved the focus from the optimal duration of DAPT to the potential efficacy of single antiplatelet therapy after DES implantation. In this Review, we summarize the current evidence on the duration of DAPT and the risk of bleeding and adverse cardiac events after DES implantation, and describe the pitfalls of trial interpretation. The ongoing, prospective trials to test single antiplatelet therapy after DES implantation are also discussed.

Dyspnea in patients treated with P2Y12 receptor antagonists: insights from the GReek AntiPlatElet (GRAPE) registry

In 'real life' acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI) and receiving contemporary antiplatelet treatment, data on dyspnea occurrence and impact on persistence with treatment are scarce. In a prospective, multicenter, cohort study, ACS patients undergoing PCI were recruited into the GReekAntiPlatElet (GRAPE) registry. During 1-year follow up, overall, 249/1989 (12.5%) patients reported dyspnea, more frequently at 1-month and decreasing thereafter. Multivariate analysis showed that ticagrelor administration (n = 738) at discharge was associated with the occurrence of dyspnea: Odds ratio 2.46 (95% confidence interval, CI, 1.87-3.25), p < 0.001. Older age, lower hematocrit, and prior bleeding event were also associated with dyspnea reports. Persistence, switching, and cessation rates were 68.3%, 20.9%, and 10.8% vs 76.7%, 12.5%, and 10.9% among patients reporting dyspnea compared with those who did not, p for trend = 0.002. In conclusion, in ACS patients undergoing PCI and treated with a P2Y₁₂ receptor antagonist, dyspnea occurs commonly, particularly when ticagrelor is administered. Non-persistence with antiplatelet agents at discharge is more frequently observed among dyspnea-reporters.

A semi-quantitative translational pharmacology analysis to understand the relationship between in vitro ENT1 inhibition and the clinical incidence of dyspnoea and bronchospasm

Adenosine contributes to the pathophysiology of respiratory disease, and adenosine challenge leads to bronchospasm and dyspnoea in patients. The equilibrative nucleoside transporter 1 (ENT1) terminates the action of adenosine by removal from the extracellular environment. Therefore, it is proposed that inhibition of ENT1 in respiratory disease patients leads to increased adenosine concentrations, triggering bronchospasm and dyspnoea. This study aims to assess the translation of in vitro ENT1 inhibition to the clinical incidence of bronchospasm and dyspnoea in respiratory disease, cardiovascular disease and healthy volunteer populations. Four marketed drugs with ENT1 activity were assessed; dipyridamole, ticagrelor, draflazine, cilostazol. For each patient population, the relationship between in vitro ENT1 [³H]-NBTI binding affinity (K_i) and [³H]-adenosine uptake (IC₅₀) to the incidence of: (1) bronchospasm/severe dyspnoea; (2) tolerated dyspnoea and; (3) no adverse effects, was evaluated. A high degree of ENT1 inhibition (≥13.3x K_i, ≥4x IC₅₀) associated with increased incidence of bronchospasm/severe dyspnoea for patients with respiratory disease only, whereas a lower degree of ENT1 inhibition (≥0.1x K_i, ≥0.05x IC₅₀) associated with a tolerable level of dyspnoea in both respiratory and cardiovascular disease patients. ENT1 inhibition had no effect in healthy volunteers. Furthermore, physicochemical properties correlative with ENT1 binding were assessed using a set of 1625 diverse molecules. Binding to ENT1 was relatively promiscuous (22% compounds K_i<1μM) especially for neutral or basic molecules, and greater incidence tracked with higher lipophilicity (clogP >5). This study rationalises inclusion of an assessment of ENT1 activity during early safety profiling for programs targeting respiratory disorders.

Genotyping-guided approach versus the conventional approach in selection of oral P2Y12 receptor blockers in Chinese patients suffering from acute coronary syndrome

Objective The CYP2C19 loss-of-function (LoF) allele is present in half of the East Asian population and is associated with high on-treatment platelet reactivity (HTPR). This study aimed to investigate whether a rapid genotyping-guided approach is feasible and efficacious for selecting P2Y12 receptor blockers in Chinese patients suffering from acute coronary syndrome (ACS). Methods This was a single-centre, prospective, randomized, open-label study. A total of 132 patients with ACS were randomized to the rapid genotyping-guided treatment group (GG, N = 65) or the standard treatment group (SG, N = 67). Patients in the GG group were genotyped by the Verigene system. Patients with the CYP2C19 LoF allele were switched to ticagrelor and all remaining patients continued on clopidogrel. The endpoints were HTPR at 24 hours after the first loading dose of clopidogrel and 1 month afterwards. Results Forty patients in the GG group switched to ticagrelor, while others continued on clopidogrel. The incidence of HTPR in the GG vs SG groups was 9.2% vs 40.3% at 24 hours and 6.5% vs 32.3% at 1 month, respectively. Rapid point-of-care genotyping showed 100% concordance with conventional genotyping by real-time polymerase chain reaction. Conclusions In Chinese patients suffering from ACS, the rapid genotyping-guided approach for selecting P2Y12 receptor blockers is feasible and reduces the incidence of HTPR. Clinical Trial Registration URL: http://clinicaltrials.gov . Unique identifier: NCT01994941.

Novel strategies for assessing platelet reactivity

There are many approaches to assessing platelet reactivity and many uses for such measurements. Initially, measurements were based on the ability of platelets separated from other blood cells to aggregate together following activation with an appropriate 'aggregating agent'. Later, measurements of platelet aggregation in blood itself were performed, and this led to a point-of-care approach to platelet function testing. Measurement of secretory activity through the appearance of the activation marker P-selectin on platelets now provides an alternative approach, which enables remote testing. Measurement of vasodilator-stimulated phosphoprotein phosphorylation is also moving toward application in situations remote from the testing laboratory. Here we provide an overview of the various approaches that are now available, assess their advantages and disadvantages, and describe some of the clinical situations in which they are being used.

Long-term ticagrelor monotherapy versus standard dual antiplatelet therapy followed by aspirin monotherapy in patients undergoing biolimus-eluting stent implantation: rationale and design of the GLOBAL LEADERS trial

AIMS

The GLOBAL LEADERS trial is a superiority study in patients undergoing percutaneous coronary intervention, with a uniform use of Biolimus A9-eluting stents (BES) and bivalirudin. GLOBAL LEADERS was designed to assess whether a 24-month antithrombotic regimen with ticagrelor and one month of acetylsalicylic acid (ASA), compared to conventional dual antiplatelet therapy (DAPT), improves outcomes.

METHODS AND RESULTS

Patients (n >16,000) are randomised (1:1 ratio) to ticagrelor 90 mg twice daily for 24 months plus ASA ≤100 mg for one month versus DAPT with either ticagrelor (acute coronary syndrome) or clopidogrel (stable coronary artery disease) for 12 months plus ASA ≤100 mg for 24 months. The primary outcome is a composite of all-cause mortality or non-fatal, new Q-wave myocardial infarction at 24 months. The key safety endpoint is investigator-reported class 3 or 5 bleeding according to the Bleeding Academic Research Consortium (BARC) definitions. Sensitivity analysis will be carried out to explore potential differences in outcome across geographic regions and according to specific angiographic and clinical risk estimates.

CONCLUSIONS

The GLOBAL LEADERS trial aims to assess the role of ticagrelor as a single antiplatelet agent after a short course of DAPT for the long-term prevention of cardiac adverse events, across a wide spectrum of patients, following BES implantation.

Protective Effects of Ticagrelor on Myocardial Injury After Infarction

BACKGROUND

The P2Y₁₂ receptor antagonist ticagrelor has been shown to be clinically superior to clopidogrel. Although the underlying mechanisms remain elusive, ticagrelor may exert off-target effects through adenosine-related mechanisms. We aimed to investigate whether ticagrelor reduces myocardial injury to a greater extent than clopidogrel after myocardial infarction (MI) at a similar level of platelet inhibition and to determine the underlying mechanisms.

METHODS

Pigs received the following before MI induction: (1) placebo-control; (2) a loading dose of clopidogrel (600 mg); (3) a loading dose of ticagrelor (180 mg); or (4) a loading dose of ticagrelor followed by an adenosine A1/A2-receptor antagonist [8-(p-sulfophenyl)theophylline, 4 mg/kg intravenous] to determine the potential contribution of adenosine in ticagrelor-related cardioprotection. Animals received the corresponding maintenance doses of the antiplatelet agents during the following 24 hours and underwent 3T-cardiac MRI analysis. Platelet inhibition was monitored by ADP-induced platelet aggregation. In the myocardium, we assessed the expression and activation of proteins known to modulate edema formation, including aquaporin-4 and AMP-activated protein kinase and its downstream effectors CD36 and endothelial nitric oxide synthase and cyclooxygenase-2 activity.

RESULTS

Clopidogrel and ticagrelor exerted a high and consistent antiplatelet effect (68.2% and 62.2% of platelet inhibition, respectively, on challenge with 20 μmol/L ADP) that persisted up to 24 hours post-MI (P<0.05). All groups showed comparable myocardial area-at-risk and cardiac worsening after MI induction. 3T-Cardiac MRI analysis revealed that clopidogrel- and ticagrelor-treated animals had a significantly smaller extent of MI than placebo-control animals (15.7 g left ventricle and 12.0 g left ventricle versus 22.8 g left ventricle, respectively). Yet, ticagrelor reduced infarct size to a significantly greater extent than clopidogrel (further 23.5% reduction; P=0.0026), an effect supported by troponin-I assessment and histopathologic analysis (P=0.0021). Furthermore, in comparison with clopidogrel, ticagrelor significantly diminished myocardial edema by 24.5% (P=0.004), which correlated with infarct mass (r=0.73; P<0.001). 8-(p-Sulfophenyl)theophylline administration abolished the cardioprotective effects of ticagrelor over clopidogrel. At a molecular level, aquaporin-4 expression decreased and the expression and activation of AMP-activated protein kinase signaling and cyclooxygenase-2 increased in the ischemic myocardium of ticagrelor- versus clopidogrel-treated animals (P<0.05). These protein changes were not observed in those animals administered the adenosine receptor blocker 8-(p-sulfophenyl)theophylline.

CONCLUSIONS

Ticagrelor, beyond its antiplatelet efficacy, exerts cardioprotective effects by reducing necrotic injury and edema formation via adenosine-dependent mechanisms.

Stent Thrombosis Patients with Hyporesponsiveness to Clopidogrel, Prasugrel, and Ticagrelor: A Case Series Using Short Thromboelastography

Patients after percutaneous coronary intervention (PCI) with stent implantation and functional hyporesponsiveness to P₂Y₁₂ inhibitors are at higher risk of ischaemic events, particularly stent thrombosis (ST). It is currently not routine practice to assess the functional response to these agents. However, concern over functional hyporesponsiveness to clopidogrel has led to widespread uptake of prasugrel and ticagrelor as the default P₂Y₁₂ inhibitor after stent implantation in patients with acute coronary syndrome. Here we report, for the first time, 3 cases in which patients who have had ST exhibit hyporesponsiveness to clopidogrel, prasugrel, and ticagrelor.

Effects of Ticagrelor on Ionic Currents and Contractility in Rat Ventricular Myocytes

PURPOSE

Antiplatelet therapy has been widely used for management of patients with ischaemic heart diseases or thrombotic events. Experimental studies have shown that ticlopidine and clopidogrel decreased L-type Ca(2+) currents (ICaL), altered action potential (AP) duration and thence exerted negative inotropic effects. In this study we tested if ticagrelor, a non-thienopyridine agent, has any influence on contractile and electrical properties of isolated ventricular myocytes.

METHODS

Cardiomyocytes were isolated from male rat hearts with an enzymatic dissociation procedure and left ventricular myocytes were used for experiments. The effects of ticagrelor (1 μM) on sarcomere shortening, ionic currents and action potentials were measured at 36 ± 1 °C.

RESULTS

Ticagrelor significantly reduced ICaL density (~18%, p < 0.01) of ventricular myocytes and this effect was reversible. In consistence, it also decreased sarcomere shortening of electrically stimulated cardiomyocytes (13%, p < 0.05), while it did not change relaxation rates. Repolarizing K(+) currents and AP duration were unaffected by 1 μM ticagrelor application.

CONCLUSIONS

Ticagrelor exerts a significant influence on contractile properties and membrane currents of ventricular myocytes similarly to thienopyridine agents. The impact of ticagrelor on cardiac excitation-contraction coupling elements is important, since it is widely used for the treatment of patients with heart diseases.

A randomized, parallel group, double-blind study of ticagrelor compared with aspirin for prevention of vascular events in patients undergoing coronary artery bypass graft operation: Rationale and design of the Ticagrelor in CABG (TiCAB) trial: An Investigator-Initiated trial

BACKGROUND

For patients with coronary artery disease undergoing coronary bypass surgery, acetylsalicylic acid (ASA) currently represents the gold standard of antiplatelet treatment. However, adverse cardiovascular event rates in the first year after coronary artery bypass grafting (CABG) still exceed 10%. Graft failure, which is predominantly mediated by platelet aggregation, has been identified as a major contributing factor in this context. Therefore, intensified platelet inhibition is likely to be beneficial. Ticagrelor, an oral, reversibly binding and direct-acting P2Y12 receptor antagonist, provides a rapid, competent, and consistent platelet inhibition and has shown beneficial results compared with clopidogrel in the subset of patients undergoing bypass surgery in a large previous trial.

HYPOTHESIS

Ticagrelor is superior to ASA for the prevention of major cardiovascular events within 1 year after CABG.

STUDY DESIGN

The TiCAB trial (NCT01755520) is a multicenter, phase III, double-blind, double-dummy, randomized trial comparing ticagrelor with ASA for the prevention of major cardiovascular events within 12 months after CABG. Patients undergoing CABG will be randomized in a 1:1 fashion to either ticagrelor 90 mg twice daily or ASA 100 mg once daily. The study medication will be started within 24 hours after surgery and maintained for 12 months. The primary end point is the composite of cardiovascular death, myocardial infarction, stroke, and repeat revascularization at 12 months after CABG. The sample size is based on an expected event rate of 13% of the primary end point within the first 12 months after randomization in the control group, a 2-sided α level of .0492 (to preserve the overall significance level of .05 after planned interim analysis), a power of 0.80%, 2-sided testing, and an expected relative risk of 0.775 in the active group compared with the control group and a dropout rate of 2%. According to power calculations based on a superiority design for ticagrelor, it is estimated that 3,850 patients should be enrolled.

SUMMARY

There is clinical equipoise on the issue of optimal platelet inhibition after CABG. The TiCAB trial will provide a pivotal comparison of the efficacy and safety of ticagrelor compared with ASA after CABG.

Low-dose ticagrelor yields an antiplatelet efficacy similar to that of standard-dose ticagrelor in healthy subjects: an open-label randomized controlled trial

Ticagrelor has a greater antiplatelet efficacy than clopidogrel but may be accompanied by an increased risk of bleeding. This study evaluated the antiplatelet effect and pharmacokinetic profile of low-dose ticagrelor in healthy Chinese volunteers. Thirty healthy subjects were randomized to receive standard-dose ticagrelor (180-mg loading dose, 90-mg twice daily [bid] [n = 10]), low-dose ticagrelor (90-mg loading dose, 45-mg bid [n = 10]), or clopidogrel (600-mg loading dose, 75-mg once daily [n = 10]). Platelet reactivity was assessed by using the VerifyNow P2Y12 assay at baseline and 0.5, 1, 2, 4, 8, 24, 48, and 72 hours post-dosing. The ticagrelor and AR-C124910XX concentrations were measured for pharmacokinetic analysis. The percentage inhibition of P2Y12 reaction units was higher in the low-dose and standard-dose ticagrelor group than in the clopidogrel group at 0.5, 1, 2, 4, 8, and 48 hours post-dosing (P < 0.05 for all), but did not differ significantly between the two ticagrelor doses at any time-point (P > 0.05). The plasma ticagrelor and ARC124910XX concentrations were approximately 2-fold higher with standard-dose versus low-dose ticagrelor. No serious adverse events were reported. In conclusion, low-dose ticagrelor achieved faster and higher inhibition of platelet functions in healthy Chinese subjects than did clopidogrel, with an antiplatelet efficacy similar to that of standard-dose ticagrelor.

Outcomes in patients treated with ticagrelor or clopidogrel after acute myocardial infarction: experiences from SWEDEHEART registry

AIMS

Ticagrelor reduces ischaemic events and mortality in acute coronary syndrome (ACS) vs. clopidogrel. We wished to study clinical outcomes in a large real-world population post-ACS.

METHODS AND RESULTS

We performed a prospective cohort study in 45 073 ACS patients enrolled into Swedish Web system for Enhancement and Development of Evidence-based care in Heart Disease Evaluated According to Recommended Therapies who were discharged on ticagrelor (N = 11 954) or clopidogrel (N = 33 119) between 1 January 2010 and 31 December 2013. The primary outcome was a composite of all-cause death, re-admission with myocardial infarction (MI) or stroke, secondary outcomes as the individual components of the primary outcome, and re-admission with bleeding. The risk of the primary outcome with ticagrelor vs. clopidogrel was 11.7 vs. 22.3% (adjusted hazard ratio (HR) 0.85 [95% confidence interval: 0.78-0.93]), risk of death 5.8 vs. 12.9% (adjusted HR 0.83 [0.75-0.92]), and risk of MI 6.1 vs. 10.8% (adjusted HR 0.89 [0.78-1.01]) at 24 months. Re-admission with bleeding with ticagrelor vs. clopidogrel occurred in 5.5 vs. 5.2% (adjusted HR 1.20 [1.04-1.40]). In a subset of patients undergoing percutaneous coronary intervention (PCI) on ticagrelor vs. clopidogrel the PCI-related in-hospital bleeding was 3.7 vs. 2.7% (adjusted odds ratio, OR, 1.57 [1.30-1.90]).

CONCLUSION

Ticagrelor vs. clopidogrel post-ACS was associated with a lower risk of death, MI, or stroke, as well as death alone. Risk of bleeding was higher with ticagrelor. These real-world outcomes are consistent with randomized trial results.

Ticagrelor versus Aspirin in Acute Stroke or Transient Ischemic Attack

BACKGROUND

Ticagrelor may be a more effective antiplatelet therapy than aspirin for the prevention of recurrent stroke and cardiovascular events in patients with acute cerebral ischemia.

METHODS

We conducted an international double-blind, controlled trial in 674 centers in 33 countries, in which 13,199 patients with a nonsevere ischemic stroke or high-risk transient ischemic attack who had not received intravenous or intraarterial thrombolysis and were not considered to have had a cardioembolic stroke were randomly assigned within 24 hours after symptom onset, in a 1:1 ratio, to receive either ticagrelor (180 mg loading dose on day 1 followed by 90 mg twice daily for days 2 through 90) or aspirin (300 mg on day 1 followed by 100 mg daily for days 2 through 90). The primary end point was the time to the occurrence of stroke, myocardial infarction, or death within 90 days.

RESULTS

During the 90 days of treatment, a primary end-point event occurred in 442 of the 6589 patients (6.7%) treated with ticagrelor, versus 497 of the 6610 patients (7.5%) treated with aspirin (hazard ratio, 0.89; 95% confidence interval [CI], 0.78 to 1.01; P=0.07). Ischemic stroke occurred in 385 patients (5.8%) treated with ticagrelor and in 441 patients (6.7%) treated with aspirin (hazard ratio, 0.87; 95% CI, 0.76 to 1.00). Major bleeding occurred in 0.5% of patients treated with ticagrelor and in 0.6% of patients treated with aspirin, intracranial hemorrhage in 0.2% and 0.3%, respectively, and fatal bleeding in 0.1% and 0.1%.

CONCLUSIONS

In our trial involving patients with acute ischemic stroke or transient ischemic attack, ticagrelor was not found to be superior to aspirin in reducing the rate of stroke, myocardial infarction, or death at 90 days. (Funded by AstraZeneca; ClinicalTrials.gov number, NCT01994720.).

Impact of glycoprotein IIb/IIIa inhibitors on the efficacy and safety of ticagrelor compared with clopidogrel in patients with acute coronary syndromes: Analysis from the Platelet Inhibition and Patient Outcomes (PLATO) Trial

BACKGROUND

Ticagrelor reduced cardiovascular events compared with clopidogrel in PLATO without increasing overall major bleeding. We evaluated whether the use of glycoprotein IIb/IIIa inhibitor (GPI) impacts the relative efficacy and safety of ticagrelor compared with clopidogrel.

METHODS

PLATO randomized 18,624 subjects with acute coronary syndrome to ticagrelor versus clopidogrel. The primary efficacy end point was cardiovascular death/myocardial infarction/stroke, and the primary safety end point was major bleeding. The use of GPI was at the physician's discretion and open-label. We evaluated outcomes at 30 days stratified by GPI use in the subgroup of 9,983 patients who underwent percutaneous coronary intervention (PCI) within 72 hours.

RESULTS

A total of 4,020 (40%) received a GPI. Those receiving a GPI were more likely to be younger, be male, and undergo multivessel PCI. There was no interaction between treatment and GPI use for the primary efficacy and safety end points. Patients treated without GPI had a lower rate of definite stent thrombosis and higher rate of minor/major bleeding with ticagrelor compared with clopidogrel (P < .05), whereas there was no such difference with GPI (P interaction < .05).

CONCLUSIONS

In patients with acute coronary syndrome undergoing early PCI, the efficacy and safety of ticagrelor as compared with clopidogrel were not modified by GPI use according to the primary efficacy and safety end point of the trial, although there were indications of greater benefit on definite stent thrombosis and more major or minor bleeding with ticagrelor in patients without (vs with) GPI treatment.

Ticagrelor for the treatment of atherosclerotic disease: insights from the PARTHENON clinical development program

Ticagrelor (P2Y12 receptor antagonist) is presently indicated for preventing atherothrombotic events in patients with acute coronary syndrome and patients with a history of myocardial infarction. The PARTHENON clinical development program comprises five randomized, controlled, cardiovascular, indication-seeking outcome studies, aiming to evaluate ticagrelor across the spectrum of patients with atherothrombotic disease. Results of two large-scale trials support a benefit for ticagrelor in patients with acute coronary syndrome (PLATO; ClinicalTrials.gov: NCT00391872) and in patients with a history of myocardial infarction (PEGASUS-TIMI 54; ClinicalTrials.gov: NCT01225562). Ongoing trials will provide information on the efficacy and safety of ticagrelor in patients with acute ischemic stroke or transient ischemic attack (SOCRATES; ClinicalTrials.gov: NCT01994720), peripheral artery disease (EUCLID; ClinicalTrials.gov: NCT01732822) and coronary artery disease in patients with Type 2 diabetes mellitus (THEMIS: ClinicalTrials.gov: NCT01991795).

Pharmacodynamics, pharmacokinetics, and safety of ticagrelor in Chinese patients with stable coronary artery disease

AIM

The aim of the study was to assess ticagrelor's effects on inhibition of platelet aggregation (IPA), P2Y12 reaction units (PRU, measure of platelet P2Y12 receptor blockade), pharmacokinetic (PK) parameters and safety in Chinese patients with stable coronary artery disease (CAD).

METHODS

This was an open label, single centre, randomized study. Thirty-six patients on low dose aspirin (75-100 mg day(-1) ) received ticagrelor 45, 60 or 90 mg (single dose, days 1 and 7; twice daily, days 3-6). IPA (final extent), PRU and ticagrelor and AR-C124910XX plasma concentrations were determined.

RESULTS

On day 1, peak IPA >80% occurred 2-6 h post-dose (all doses). PRU was markedly reduced at 1 h vs. baseline (all doses). With ticagrelor 45 and 90 mg twice daily, maximum IPA (mean, SD) was 91% (13%), and 99% (3%), and maximum PRU reduction from baseline (mean, SD) was 82% (17%) and 92% (9%), respectively. Approximate dose-proportional increases (mean [%CV]; 45 vs. 90 mg twice daily) in ticagrelor Cmax (616 [37] vs. 1273 [43] ng ml(-1) ) and AUC (3882 [42] vs. 8206 [51] ng ml(-1) h) and AR-C124910XX parameters were seen. Pharmacodynamic and PK differences between 45 and 60 mg were small. No safety issues were identified.

CONCLUSIONS

In Chinese patients with CAD, ticagrelor (45, 60 and 90 mg) markedly reduced platelet aggregation. The IPA and PRU magnitude increased generally with increasing doses. However, the mean pharmacodynamic differences between 45 and 60 mg doses were small. Following single and multiple doses, the mean Cmax and AUC values of ticagrelor and AR-C124910XX increased approximately dose proportionally between 45 and 90 mg doses.

Infarct Size Following Treatment With Second- Versus Third-Generation P2Y12 Antagonists in Patients With Multivessel Coronary Disease at ST-Segment Elevation Myocardial Infarction in the CvLPRIT Study

Background

Third‐generation P2Y₁₂ antagonists (prasugrel and ticagrelor) are recommended in guidelines on ST‐segment elevation myocardial infarction. Mechanisms translating their more potent antiplatelet activity into improved clinical outcomes versus the second‐generation P2Y₁₂ antagonist clopidogrel are unclear. The aim of this post hoc analysis of the Complete Versus Lesion‐Only PRImary PCI Trial‐CMR (CvLPRIT‐CMR) substudy was to assess whether prasugrel and ticagrelor were associated with reduced infarct size compared with clopidogrel in patients undergoing primary percutaneous coronary intervention.

Methods and Results

CvLPRIT‐CMR was a multicenter, prospective, randomized, open‐label, blinded end point trial in 203 ST‐segment elevation myocardial infarction patients with multivessel disease undergoing primary percutaneous coronary intervention with either infarct‐related artery–only or complete revascularization. P2Y₁₂ inhibitors were administered according to local guidelines. The primary end point of infarct size on cardiovascular magnetic resonance was not significantly different between the randomized groups. P2Y₁₂ antagonist administration was not randomized. Patients receiving clopidogrel (n=70) compared with those treated with either prasugrel or ticagrelor (n=133) were older (67.8±12 versus 61.5±10 years, P<0.001), more frequently had hypertension (49% versus 29%, P=0.007), and tended to have longer symptom‐to‐revascularization time (234 versus 177 minutes, P=0.05). Infarct size (median 16.1% [quartiles 1–3, 10.5–27.7%] versus 12.1% [quartiles 1–3, 4.8–20.7%] of left ventricular mass, P=0.013) and microvascular obstruction incidence (65.7% versus 48.9%, P=0.022) were significantly greater in patients receiving clopidogrel. Infarct size remained significantly different after adjustment for important covariates using both generalized linear models (P=0.048) and propensity score matching (P=0.025).

Conclusions

In this analysis of CvLPRIT‐CMR, third‐generation P2Y₁₂ antagonists were associated with smaller infarct size and lower microvascular obstruction incidence versus the second‐generation P2Y₁₂ antagonist clopidogrel for ST‐segment elevation myocardial infarction.

Clinical Trial Registration

URL: http://www.isrctn.com/ISRCTN70913605.

Simultaneous Determination of Ticagrelor and Its Metabolites in Human Plasma and Urine Using Liquid Chromatography-Tandem Mass Spectrometry

We have developed and validated a rapid, selective and sensitive method using high-performance liquid chromatography-tandem mass spectrometry (MS) for the quantification of ticagrelor and all of its as-yet-identified metabolites in human plasma and urine. For the analysis of ticagrelor, its metabolites and the internal standard (IS) plasma samples were processed by liquid-liquid extraction using ethyl acetate and urine was processed by protein precipitation. Separations were performed on an Ultimate XB-C18 column (2.1 mm × 150 mm, 3 μm), using aqueous ammonium acetate (0.025 mM)/acetonitrile (35 : 65, v:v) as the mobile phase. Ticagrelor and all 11 metabolites were eluted within 4.5 min. Quantification was performed using electrospray ionization, operating in negative ion mode. The ticagrelor and metabolite M8 (AR-C124910XX) responses were optimized at the m/z 521.2 → 361.2 and m/z 477.2 → 361.1 transitions, respectively. The assay was validated over the linear range of 0.5-2,000 ng/mL for ticagrelor and M8. The intra- and inter-assay precisions were ≤14.6% for ticagrelor and ≤14.7% for M8, respectively. The matrix effects of plasma and urine were in the range of 98.3-110.7% for ticagrelor and 102.1-112.3% for M8. The relative quantification of other metabolites was performed by assessing the ratio of metabolite to IS peaks. The newly developed method was successfully used in a pharmacokinetic study characterizing ticagrelor metabolism in human volunteers.

Design and rationale for the Effects of Ticagrelor and Clopidogrel in Patients with Peripheral Artery Disease (EUCLID) trial

BACKGROUND

Despite overwhelming data demonstrating the efficacy of antiplatelet therapy in heart disease and stroke, data in peripheral artery disease (PAD) are less compelling. Aspirin has modest evidence supporting a reduction in cardiovascular events in patients with PAD, whereas clopidogrel monotherapy may be more effective in PAD. Ticagrelor, a potent, reversibly binding P2Y12 receptor antagonist, is beneficial in patients with acute coronary syndrome and prior myocardial infarction. The EUCLID trial is designed to address the need for effective antiplatelet therapy in PAD to decrease the risk of cardiovascular events.

STUDY DESIGN

EUCLID is a randomized, double-blind, parallel-group, multinational clinical trial designed to evaluate the efficacy and safety of ticagrelor compared with clopidogrel for the prevention of major adverse cardiovascular events in subjects with symptomatic PAD. Subjects with established PAD will be randomized in a 1:1 fashion to ticagrelor 90 mg twice daily or clopidogrel 75 mg daily. The primary end point is a composite of cardiovascular death, myocardial infarction, or ischemic stroke. Other end points address limb events including acute leg ischemia, need for revascularization, disease progression by ankle-brachial index, and quality of life. The primary safety objective is Thrombolysis in Myocardial Infarction-defined major bleeding. Recruitment began in December 2012 and was completed in March 2014; 13,887 patients were randomized. The trial will continue until at least 1,364 adjudicated primary end points occur.

CONCLUSIONS

The EUCLID study is investigating whether treatment with ticagrelor versus clopidogrel, given as antiplatelet monotherapy, will reduce the incidence of cardiovascular and limb-specific events in patients with symptomatic PAD.

Design and Rationale of the APELOT Trial: A Randomized, Open-Label, Multicenter, Phase IV Study to Evaluate the Antiplatelet Effect of Different Loading Dose of Ticagrelor in Patients With Non-ST Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention

Ticagrelor is a direct acting on the P2Y12 receptor blocker, which provides faster and greater platelet inhibition than clopidogrel. However, several studies suggested that in ST-segment elevation myocardial infarction patients undergoing percutaneous coronary intervention (PCI), ticagrelor exhibits initial delay in the onset of antiplatelet action. Unlike ST-segment elevation myocardial infarction, in non-ST-segment elevation acute coronary syndrome (NSTE-ACS), management pathways are highly variable, and some patients may require surgery. Effect of higher loading dose (LD) of ticagrelor in patients with NSTE-ACS in providing faster and stronger inhibition of platelet aggregation is unknown and needs to be explored further.The AntiPlatelet Effect of different Loading dOse of Ticagrelor trial is an interventional, randomized, open-label, multicenter, phase IV trial designed to evaluate whether a high LD (360 mg) of ticagrelor compared with the conventional LD (180 mg) will result in a higher inhibition of platelet aggregation without increasing bleeding events in NSTE-ACS participants undergoing PCI.A total of 250 NSTE-ACS participants will be randomized to receive a ticagrelor LD (360 or 180 mg), followed by a maintenance dose of 90 mg twice a day (bid) starting 12 hours after the LD. The primary endpoint is platelet reactivity index measured by vasodilator-stimulated phosphoprotein phosphorylation 2 hours after the LD, and the secondary endpoints include occurrence of periprocedural myocardial infarction and bleeding events.The AntiPlatelet Effect of different Loading dOse of Ticagrelor trial will provide important information on the risks and benefits of a high LD (360 mg) of ticagrelor in achieving a faster and stronger platelet inhibition compared with the conventional LD (180 mg) in NSTE-ACS patients undergoing PCI.

Clinical effect of ticagrelor administered in acute coronary syndrome patients following percutaneous coronary intervention

The aim of the present study was to retrospectively analyze the clinical effect and safety of ticagrelor administration in acute coronary syndrome (ACS) patients following percutaneous coronary intervention (PCI). In total, 203 patients were enrolled, who were confirmed with ACS between March 2013 and May 2013, and had successfully undergone PCI. The patients were randomly divided into two groups, including the clopidogrel (group A, n=108) and ticagrelor groups (group B, n=95). Patients in group A were treated with a 600 mg loading dose of clopidogrel followed by 75 mg/day clopidogrel plus 100 mg/day aspirin. Patients in group B received a 180 mg loading dose of ticagrelor followed by 90 mg ticagrelor twice daily plus 100 mg/day aspirin. Light transmission aggregometry was performed to measure the platelet aggregation rate prior to and following 4 weeks of anti-platelet drug treatment. In addition, the rate of cardiovascular events and the adverse drug reactions were recorded within a 1-year treatment period. Compared with the clopidogrel group, the rate of recurrent angina in the ticagrelor group was significantly lower (P=0.05). However, the rate of dyspnea in the ticagrelor group was significantly higher when compared with that in the clopidogrel group (P=0.03). After 4 weeks of treatment, the reduction in the platelet aggregation rate was significantly different between the two groups (P<0.05). Therefore, ticagrelor, which is a novel antiplatelet aggregation drug, may reduce the rate of the adverse cardiovascular events in ACS patients following PCI, but a higher incidence of side-effects, such as dyspnea, may be observed.

Antiplatelet Therapy in Percutaneous Coronary Intervention

Platelets play a key role in mediating stent thrombosis, which is the major cause of ischemic events immediately after percutaneous coronary intervention (PCI). Antiplatelet therapy is therefore the cornerstone of antithrombotic therapy after PCI. However, the use of antiplatelet agents increases bleeding risk, with more potent antiplatelet agents further increasing bleeding risk. In the past 5 years, potent and fast-acting P2Y12 inhibitors have augmented the antiplatelet armamentarium available to interventional cardiologists. This article reviews the preclinical and clinical data surrounding these new agents, and discusses the significant questions and controversies that still exist regarding the optimal antiplatelet strategy.