Detection of functional differences between different platelet membrane glycoprotein Ibalpha variable number tandem repeat and Kozak genotypes as shown by the PFA-100 system

The pharmacogenetic control of antiplatelet response: candidate genes and CYP2C19

INTRODUCTION

Aspirin, clopidogrel, prasugrel and ticagrelor are antiplatelet agents for the prevention of ischemic events in patients with acute coronary syndromes (ACS), percutaneous coronary intervention (PCI) and other indications. Variability in response is observed to different degrees with these agents, which can translate to increased risks for adverse cardiovascular events. As such, potential pharmacogenetic determinants of antiplatelet pharmacokinetics, pharmacodynamics and clinical outcomes have been actively studied.

AREAS COVERED

This article provides an overview of the available antiplatelet pharmacogenetics literature. Evidence supporting the significance of candidate genes and their potential influence on antiplatelet response and clinical outcomes are summarized and evaluated. Additional focus is directed at CYP2C19 and clopidogrel response, including the availability of clinical testing and genotype-directed antiplatelet therapy.

EXPERT OPINION

The reported aspirin response candidate genes have not been adequately replicated and few candidate genes have thus far been implicated in prasugrel or ticagrelor response. However, abundant data support the clinical validity of CYP2C19 and clopidogrel response variability among ACS/PCI patients. Although limited prospective trial data are available to support the utility of routine CYP2C19 testing, the increased risks for reduced clopidogrel efficacy among ACS/PCI patients that carry CYP2C19 loss-of-function alleles should be considered when genotype results are available.

Pharmacogenomics in cardiovascular disease: focus on aspirin and ADP receptor antagonists

Antiplatelet agents like aspirin and adenosine diphosphate receptor antagonists are effective in reducing recurrent ischemic events. Considerable inter-individual variability in the platelet inhibition obtained with these drugs has initiated a search for explanatory mechanisms and ways to improve treatment. In recent years, numerous genetic polymorphisms have been linked with reduced platelet inhibition and lack of clinical efficacy of antiplatelet drugs, particularly clopidogrel and aspirin. Consequently, attempts to adjust antiplatelet treatment according to genotype have been made, but the clinical benefit has been modest in studies performed so far. The progress in genome science over the last decade and the declining cost of sequencing technologies hold the promise of enabling genetically tailored antiplatelet therapy. However, more evidence is needed to clarify which polymorphisms may serve as targets to improve treatment. The present review outlines the panel of polymorphisms affecting the benefit of aspirin and adenosine diphosphate receptor antagonists, including novel and ongoing studies evaluating whether genotyping may be beneficial in tailoring antiplatelet therapy.