The use of ticagrelor versus clopidogrel in Malaysian patients with coronary artery disease undergoing percutaneous coronary intervention (PCI): Does the age tertile affect the platelet reactivity?

Funding Acknowledgements

Type of funding sources: None.

Background

Previous studies have shown that the prevalence of cardiovascular diseases is related to the patient's age and gender differences, but the effect of age on platelet function remains controversial. Platelet function should be tested and its efficacy correlates with the age of patients undergoing percutaneous coronary intervention (PCI) using vasodilator-associated stimulated phosphoprotein (VASP). VASP is a gold standard to assess P2Y12 receptor inhibition among patients using ticagrelor or clopidogrel.

Purpose

We sought to compare the effect of ticagrelor versus clopidogrel on the platelet function of patients undergoing PCI and the correlation of age in this effect.

Method

This study was a prospective, randomized, parallel design, an open-label investigation conducted on Malaysian patients undergoing PCI. It included 84 patients (40 patients taking ticagrelor, and 44 patients taking clopidogrel). The induced platelet reactivity was assessed by measuring total whole blood at one standardized time point after 4 hours of loading dose of ticagrelor 180 mg or clopidogrel with 600 mg and by age tertiles.

Result

The study population consisted of 23 (57.5%) patients in Tertile 1 <60 years of age, 11 (27.5%) patients in Tertile 2 between 60-70 years of age and 6 (15.0%) patients in Tertile 3 >70 years of age. The number of patients who used ticagrelor was 17 (38.64%) in Tertile 1, 21 (47.73%) in Tertile 2, and 6 (13.64%) in Tertile 3 of those who used clopidogrel. The results of platelet reactivity index was high in the patients who used clopidogrel compared to the ticagrelor group, which were 52.3% and 2.5 %, P <0.001. This effect in the clopidogrel group included all age groups without exception and at different rates (52.9%, 52.4%, and 50%, P= 0.992), respectively, but this effect was numerical and not statistically significant. In contrast to the ticagrelor group, no numerical or significant effect was observed in all age groups (4.3%, 0.0%, and 0.0%, P= 0.259), respectively (Figure 1). In addition, the results of the current cross-sectional age classification study showed no statistical differences between the clopidogrel and ticagrelor groups based on non high platelet reactivity (NHPR) (P = 0.284, P = 0.270, P = 0.796 respectively) (Figure2).

Conclusion

Our study showed that age could not be considered a risk factor in the Malaysian population, as it did not significantly affect platelet aggregation in patients with coronary artery disease undergoing percutaneous coronary intervention (PCI).

Platelet reactivity index after treatment of clopidogrel versus ticagrelor based on CYP2C19 genotypes among patients undergoing percutaneous coronary intervention: results of a randomized study

Funding Acknowledgements

Type of funding sources: None.

Background

Although clopidogrel is the basic drug for antiplatelet therapy in patients with coronary artery disease (CAD). However, loss of function (LOF) allelic variants located within the CYP2C19 gene may reduce the production of clopidogrel active metabolites and weaken the antiplatelet effect, increasing platelet rates reactivity and associated with increased rates of adverse events after percutaneous coronary intervention (PCI). Thus, drug regulatory authorities have warned of clopidogrel's reduced efficacy and suggested using alternative treatments (such as ticagrelor). However, in clinical practice, the strategy of genotype-guided selection for antiplatelet therapy has been limited by the lack of access to immediately available results.

Purpose

We sought to evaluate the effect of point-of-care genetic testing for CYP2C19 genotypes on the antiplatelet choice of therapy (i.e., clopidogrel vs ticagrelor), using platelet reactivity index (PRI) as a proxy of clinical outcome

Method

This study was a prospective, randomized, parallel design, an open-label investigation conducted among Malaysian patients with stable coronary artery disease (SCAD) undergoing PCI. Patients underwent rapid point-of-care genetic testing using the nested allele-specific multiplex PCR assay, which defines CYP2C19 genetic status within 3 hours, allowing patients to be genotyped on the same day before PCI. Patients who were carriers of at least one +LOF or -LOF (*2 or *3) allele was randomized to receive either clopidogrel [600mg loading dose (LD) - 75mg/day maintenance dose (MD)] or ticagrelor (180mg LD - 90mg MD). The induced platelet reactivity index (PRI) was assessed by Vasodilator-Associated Stimulated Phosphoprotein (VASP) Assay to whole blood at one standardized time point after 4 hours of LD. All patients were treated with aspirin. The primary endpoint of the study was the non-inferiority in platelet reactivity, measured as PRI, at 4 hours of clopidogrel vs ticagrelor in +LOF or -LOF allele carriers

Result

In 1638 SCAD patients, 94 underwent PCI and were genotyped and randomized to receive either clopidogrel (n=44) or ticagrelor (n=50). A total of 42 (44.68%) were carriers of at least one +LOF. PRI levels at 4 hours for clopidogrel vs ticagrelor 44 and 40, respectively (mean difference = 23.08; 95% CI: 17 to 30; p=<0.001); this will meet the primary endpoint of superiority in a non-inferiority. Ticagrelor significantly reduced PRI more than clopidogrel. The cross-tabulation of the response classification showed that ticagrelor is superior to clopidogrel based on the -LOF and +LOF (P= 0.005 and <0.001, respectively)

Conclusion

A rapid point-of-care genetic test using a nested allele-specific multiplex PCR assay can be used to personalize antiplatelet therapy and provides timely results for patients undergoing PCI. In addition, the results showed that ticagrelor was superior to clopidogrel in the level of platelet inhibition in both groups (+LOF or -LOF)

Fast and more affordable CYP2C19 LOF testing to personalized of clopidogrel therapy

Background

Clopidogrel is an antiplatelet drug used to treat coronary artery disease (CAD) to reduce blood clotting by inhibiting platelet activity. However, many patients experience ischemic events due to changes in clopidogrel metabolism attributed to various genetic and non-genetic factors. CYP2C19 is one of the important genes responsible for the metabolism of clopidogrel, but this gene has polymorphisms in cytochrome P450 (CYP), and this CYP2C19 Loss-of-function (LoF) polymorphisms impair clopidogrel metabolism between individuals and races. Therefore, genetic testing is an effective strategy to personalized clopidogrel and reduce the incidence of ischemic events in CAD patients.

Purpose

We sought to develop a nested allele-specific multiplex polymerase chain reaction (PCR) method for the detection of CYP2C9 LOF alleles.

Method

Genomic DNA was extracted from blood taken from 7 healthy volunteers using a commercial DNA extraction kit. A two-step PCR method was developed. First, DNA was subjected to a first PCR used to amplify exons 4 and 5 simultaneously in a single reaction tube. Second, The products of 1st PCR were then used as a template in the second PCR to detect CYP2C9 polymorphisms alleles (CYP2C19*2 and *3) using allele-specific primers. The test results were validated via sequencing.

Result

We successfully detected clinically important CYP2C19 LOF polymorphisms alleles by the nested allele-specific multiplex PCR method (Figure 1). This method is fast and doesn't require high-quality and expensive laboratory equipment. It was reproducible and specific and can reliably detect CYP2C19 variants. Direct sequencing of target variants has been used to validate this strategy further, and the amplified sequences were 100% identical to the CYP2C9 sequence.

Conclusion

The developed methods were specific to identify polymorphisms in CYP2C19 (rs4244285 and rs4986893). However, to understand ethnic differences and their potential implications for clopidogrel therapy, we highly recommend identifying relevant genetic polymorphisms before clinical manifestations arise.

Funding Acknowledgement

Type of funding sources: None.