Cangrelor increases the magnitude of platelet inhibition and reduces interindividual variability in clopidogrel-pretreated subjects

Cangrelor - Expanding therapeutic options in patients with acute coronary syndrome

Cangrelor is the only intravenous P2Y12 receptor antagonist. It is an adenosine triphosphate analog that selectively, directly, and reversibly binds to the platelet P2Y12 receptors exerting its antiaggregatory effect. Cangrelor is characterized by linear, dose-dependent pharmacokinetics and rapid onset of action providing potent platelet inhibition exceeding 90%. Cangrelor is rapidly metabolized by endothelial endonucleotidase; thus, its half-life is 2.9 to 5.5 min, and its antiplatelet effect subsides within 60 to 90 min. Data originating from three pivotal cangrelor trials (CHAMPION PLATFORM, CHAMPION PCI, and CHAMPION PHOENIX) indicate that cangrelor reduces the risk of periprocedural thrombotic complications during percutaneous coronary intervention at the expense of mild bleedings. Its unique pharmacological properties allow it to overcome the limitations of oral P2Y12 receptor inhibitors, mainly related to the delayed and decreased bioavailability and antiplatelet effect of these agents, which are often observed in the setting of acute coronary syndrome. Subgroups of patients who could theoretically benefit the most from cangrelor include those in whom pharmacokinetics and pharmacodynamics of oral P2Y12 receptor antagonists are most disturbed, namely patients with ST-segment elevation myocardial infarction, those treated with opioids, with mild therapeutic hypothermia, or in cardiogenic shock. Cangrelor could also be useful if bridging is required in patients undergoing surgery. According to the current guidelines cangrelor may be considered in P2Y12 receptor inhibitor-naïve patients undergoing percutaneous coronary intervention in both acute and stable settings.

Cangrelor in Percutaneous Coronary Intervention: Current Status and Perspectives

Cangrelor is an intravenously administered P2Y₁₂ receptor antagonist with very fast, potent, and quickly reversible action. In the CHAMPION PHOENIX trial, cangrelor provided an improved anti-ischemic protection compared with clopidogrel, without increasing the risk of severe bleeding. Cangrelor is currently approved by drug regulating authorities for patients undergoing percutaneous coronary intervention (PCI) without prior treatment with a P2Y₁₂ receptor antagonist and not receiving a glycoprotein IIb/IIIa inhibitor, while its use is endorsed with a class IIb recommendation by the European Society of Cardiology guidelines. Several subanalyses of CHAMPION PHOENIX trial have tried to elucidate the role of cangrelor in PCI, including its usefulness during a 2-hour landmark analysis, impact on intraprocedural stent thrombosis, and reduction in myocardial infarction (MI) rate. The influence of gender, geographic region, access site, and bivalirudin use on cangrelor's effects has also been reported. In patients with ST elevation MI and in clinical scenarios of disturbed absorption of oral antiplatelet agents or in need of an intravenous agent, cangrelor may surpass oral agents' drawbacks. Transitioning to an oral agent is mandatory following cangrelor infusion discontinuation, although ticagrelor may be administered earlier without any pharmacodynamic interaction. Nevertheless, the clinical role of cangrelor in conjunction with administration of prasugrel or ticagrelor remains unclear. Accruing real-life experience is expected to improve our understanding of cangrelor's role in everyday clinical practice.

Overview of the 2014 Food and Drug Administration Cardiovascular and Renal Drugs Advisory Committee meeting regarding cangrelor

Landmark clinical trials have established the benefit of P2Y12 inhibitors in the setting of acute coronary syndrome and percutaneous coronary intervention. On February 12, 2014, the Medicines Company (Sponsor) presented efficacy and safety data regarding cangrelor to the Food and Drug Administration (FDA) Cardiovascular and Renal Drugs Advisory Committee. The Sponsor sought approval for 2 indications: (1) in the setting of percutaneous coronary intervention for the reduction of thrombotic cardiovascular events (including stent thrombosis) in patients with coronary artery disease and (2) in the setting of bridging therapy in patients with acute coronary syndrome or with stents who are at increased risk for thrombotic events (such as stent thrombosis) when oral P2Y12 therapy is interrupted because of surgery. The following is a summary of the data presented to the FDA by the Sponsor, the FDA's clinical review of cangrelor.

Cangrelor: an emerging therapeutic option for patients with coronary artery disease

OBJECTIVES

To perform a systematic up-to-date review and critical discussion of potential clinical applications of cangrelor based on its pharmacologic properties and the main findings from randomized clinical studies.

METHODS

A database search (PubMed, CENTRAL and Google Scholar) by two independent investigators, including proceedings from scientific sessions of ACC, AHA, ESC, TCT and EuroPCR, from January 1998 through December 2013.

RESULTS

Cangrelor is a potent, intravenous, direct-acting P2Y12 antagonist with rapid onset and quickly reversible action. In contrast to ticagrelor, cangrelor's interaction with thienopiridines requires termination of cangrelor infusion before switching to clopidogrel or prasugrel. According to randomized trials, a cangrelor-clopidogrel combination is relatively safe and more effective than the standard clopidogrel regimen in both urgent and elective percutaneous coronary intervention (PCI) settings, with the advantage of this drug combination fully evident when the universal definition of myocardial infarction is applied. In contrast to available antiplatelet drugs with delayed onset and offset of action, its favorable properties make cangrelor a desirable agent for ad hoc elective PCI, high risk acute coronary syndromes treated with immediate coronary stenting and for bridging those surgery patients who require periprocedural P2Y12 inhibition. Current evidence on cangrelor therapy is limited by the lack of adequately powered studies assessing cangrelor co-administration either with prasugrel or ticagrelor, suboptimal design of some of the trials favoring cangrelor, potentially attenuated benefits with modern stent design, and finally, by the lack of survival advantage.

CONCLUSIONS

With its pharmacokinetic and pharmacodynamic advantages, allowing consistent and strong P2Y12 inhibition, and with its rapid onset and swift reversal of action devoid of need for an antidote, cangrelor might improve clinical outcomes in clopidogrel-treated patients by reducing ischemic events, while maintaining a favorable safety profile. However, further studies, addressing the safety and efficacy of cangrelor on top of novel oral P2Y12 inhibitors, are warranted.

Effects of cangrelor in coronary artery disease patients with and without diabetes mellitus: an in vitro pharmacodynamic investigation

Platelets from patients with diabetes mellitus (DM) are hyper-reactive and whether cangrelor, a potent intravenous P2Y(12) receptor blocker, has differential pharmacodynamic (PD) effects according DM status is unknown. The aim of this investigation was to evaluate the in vitro PD effects of cangrelor in coronary artery disease (CAD) patients with and without DM. This prospective study enrolled 120 clopidogrel-naïve patients with CAD on aspirin therapy. PD assessments using cangrelor (500 nmol/l) in vitro included vasodilator-stimulated phosphoprotein assay to obtain the P2Y(12) reactivity index (PRI), and multiple electrode aggregometry (MEA). In a 20 patients subgroup, dose-dependent response was assessed following exposure to escalating concentrations (baseline, 5, 50, 500 and 5,000 nmol/l); thrombin generation processes were evaluated by thromboelastography (TEG). PD data were evaluable in 103 patients. No differences in baseline PD parameters were observed in DM (n = 48) and non-DM (n = 45) subjects. Cangrelor reduced PRI values irrespective of DM status (p < 0.0001), yielding no difference in patients with and without DM (16.1 ± 12.3 vs. 16.8 ± 11.3; p = 0.346). All MEA values were significantly reduced, although this was of greater magnitude with purinergic compared to non-purinergic agonists. A trend analysis showed a dose-dependent effect on platelet inhibition, with no interaction due to DM status, whereas no significant dose-dependent effect was observed for TEG-derived parameters. Therefore, in vitro cangrelor provides potent and dose-dependent blockade of the platelet P2Y(12) receptor, with no differential effect in DM and non-DM patients. In addition, in vitro cangrelor exerts moderate inhibitory effects on non-purinergic platelet signaling pathways, without modulating platelet-derived thrombin generation processes.

Evaluation of ticagrelor pharmacodynamic interactions with reversibly binding or non-reversibly binding P2Y(12) antagonists in an ex-vivo canine model

INTRODUCTION

As ticagrelor, clopidogrel and cangrelor therapies may be used in the same clinical setting, their potential pharmacodynamic interactions are of interest. Hence, we investigated possible interactions between these agents in dogs using a variety of switching protocols.

METHODS

Six male dogs all received 7 different dosing regimens separated by 1-5week washout periods: cangrelor (1μg/kg/min, intravenous infusion); ticagrelor (0.8mg/kg, oral); clopidogrel (3mg/kg, intravenous injection); cangrelor together with ticagrelor initiated 10minutes after cangrelor infusion start or clopidogrel given 30minutes after cangrelor infusion start; ticagrelor followed by clopidogrel given 3 or 7hours after ticagrelor dosing. ADP-induced whole blood platelet aggregation was measured by impedance aggregometry.

RESULTS

Mean maximum inhibition of platelet aggregation (IPA) was 81-87% at 6minutes (cangrelor), 3hours (ticagrelor) and 4hours (clopidogrel) postdosing and platelet function recovered after 1.5hours, 12hours, and 9days, respectively. IPA at 2hours post clopidogrel was reduced to 39% when clopidogrel was given during cangrelor infusion versus 69% for clopidogrel alone. With clopidogrel dosed 3hours after ticagrelor, IPA was reduced after washout of ticagrelor to 38% at 24hrs vs. 68% for clopidogrel alone, but an interaction was not seen when clopidogrel was dosed 7hours after ticagrelor. No pharmacodynamic interaction occurred between ticagrelor and cangrelor.

CONCLUSIONS

The extent of the pharmacodynamic drug-drug interactions observed between clopidogrel and cangrelor or ticagrelor apparently depends on the level of receptor occupancy when clopidogrel is administered. Importantly, no significant pharmacodynamic interaction occurred between ticagrelor/clopidogrel when clopidogrel was given at clinical trough IPA levels with ticagrelor. No significant pharmacodynamic interaction occurred with cangrelor and ticagrelor.

Relationship between Cytochrome P450 2C19*2 Polymorphism and Stent Thrombosis following Percutaneous Coronary Intervention in Chinese Patients Receiving Clopidogrel

This study investigated the relationship between the cytochrome P450 2C19 (CYP2C19) *2 polymorphism (681A) and definite stent thrombosis (ST) in patients undergoing percutaneous coronary intervention (PCI) and receiving clopidogrel (75 mg/day, orally). The CYP2C19*2 polymorphism status of 1738 Chinese patients with coronary artery disease was examined. The primary endpoint was the occurrence of definite ST during the 180-day follow-up period. The presence of at least one CYP2C19*2 allele was significantly associated with increased ST risk (19 CYP2C19*2/*2 or *1/*2 patients [2.4%] versus seven homozygous wild-type CYP2C19*1/*1 patients [0.75%]). The risk of definite ST was highest in patients with the CYP2C19*2/*2 genotype. The CYP2C19*2 genotype is associated with an increased risk of definite ST following coronary stent placement among Chinese patients with coronary artery disease receiving clopidogrel.

Review: Antiplatelet Drugs: What Comes Next?

Antiplatelet drugs are important components in the management of atherothrombotic vascular disease. However, several limitations restrict the safety and efficacy of current antiplatelet therapy in clinical practice. Interpatient variability and resistance to aspirin and/or clopidogrel has spurred efforts for the development of novel agents. Indeed, several antiplatelet drugs are at various stages of evaluation; those at advanced stage of development are the focus of this review.

Cangrelor increases the magnitude of platelet inhibition and reduces interindividual variability in clopidogrel-pretreated subjects

BACKGROUND

Inadequate platelet inhibition despite aspirin and clopidogrel therapy during and after a percutaneous coronary intervention is associated with an impaired clinical outcome. Cangrelor, a direct and reversible P2Y(12) inhibitor that is currently in development, has the potential to achieve higher levels of inhibition of ADP-induced platelet aggregation than clopidogrel. The aim of the present study was to compare the magnitude of platelet inhibition in clopidogrel-pretreated patients before and after the in vitro addition of a subtherapeutic dose of cangrelor.

METHODS

Blood samples were drawn from patients pretreated with clopidogrel and aspirin who were undergoing elective percutaneous coronary intervention (n=39). Platelet function analysis with 'classical' light transmittance aggregometry (both peak and late aggregation [at 6 min]) was performed before and after the in vitro addition of cangrelor (0.25 mumol/l) to platelet-rich plasma (PRP). After an incubation period of five minutes, platelet aggregation was induced by 5 and 20 mumol/l ADP.

RESULTS

The in vitro addition of 0.25mumol/l cangrelor to the PRP from clopidogrel-treated subjects resulted in an additional reduction in ADP-induced platelet aggregation. For ADP concentrations of 5 and 20 mumol/l, peak aggregation showed a decrease of 75 and 85%, respectively (p<0.001 for both), while late aggregation was almost completely diminished (p=0.003 and p<0.001, respectively). Furthermore, the interindividual variation in inhibition of ADP-induced platelet aggregation by clopidogrel was greatly reduced after the addition of cangrelor.

CONCLUSION

We demonstrate that the in vitro addition of even a subtherapeutic dose of cangrelor to the PRP of clopidogrel-pretreated patients results in an additional reduction of ADP-induced platelet aggregation. Moreover, cangrelor was able to diminish the interindividual variation observed in clopidogrel-inhibited platelet aggregation. (Neth Heart J 2009;17:195-8.).