Effect of genetic and coexisting polymorphisms on platelet response to clopidogrel in Chinese Han patients with acute coronary syndrome

Influence of Genetic and Epigenetic Factors of P2Y12 Receptor on the Safety and Efficacy of Antiplatelet Drugs

PURPOSE

P2Y12 receptor inhibitors are drugs that decrease the risk of stent thrombosis and lower the long-term risk of non-stent-related myocardial infarction and stroke. They inhibit the binding of adenosine diphosphate (ADP) to the P2Y12 receptor and effectively reduce platelet reactivity. However, considerable variability in the pharmacodynamics response contributes to a failure of antiplatelet therapy; this phenomenon is especially notorious for older drugs, such as clopidogrel. Some genetic polymorphisms associated with these drugs' metabolic pathway, especially in the CYP2C19 gene, can significantly decrease antiplatelet efficacy. There are few reports on the variability stemming from the target of this drug class that is the P2Y12 receptor itself.

RESULTS AND CONCLUSION

This review summarizes the results of research that focus on the influence of P2Y12 genetic polymorphisms on the pharmacodynamics and the efficacy of P2Y12 inhibitors. We found that the conclusions of the studies are unequivocal, and despite several strong candidates, such as G52T (rs6809699) or T744C (rs2046934), they may not be independent predictors of the inadequate response to the drug. Most probably, P2Y12 genetic polymorphisms contribute to the effect exerted by other gene variants (such as CYP2C19*2/*3/*17), drug interactions, or patient habits, such as smoking. Also, epigenetic modifications, such as methylation or miRNA levels, may play a role in the efficacy of antiplatelet treatment.

Multiple genetic mutations increase the risk of thrombosis associated with clopidogrel after percutaneous coronary intervention

Background: The effect of multiple mutations in CYP2C19, PON1 and ABCB1 genes on the effectiveness and safety of dual antiplatelet therapy after percutaneous coronary intervention remains unclear. Methods: In total, 263 Chinese Han patients were enrolled in this study. Platelet aggregation rates and thrombosis risk were used to compare clopidogrel responses and outcomes in patients with different numbers of genetic mutations. Results: Our study demonstrated that 74% of the patients carried more than two genetic mutations. High platelet aggregation rates were associated with genetic mutations in patients receiving clopidogrel and aspirin after percutaneous coronary intervention. Genetic mutations were closely related to the recurrence of thrombotic events, but not bleeding. The number of genes that become dysfunctional in patients is directly correlated with the risk of recurrent thrombosis. Conclusion: Compared with CYP2C19 alone or the platelet aggregation rate, it is more helpful to predict clinical outcomes by considering the polymorphisms of all three genes.

Dosage optimization of clopidogrel via a precision medicine approach: the way forward

Clopidogrel is a prodrug chiefly metabolized by the hepatic isoenzyme CYP2C19 to its active metabolite that inhibits the platelet aggregation. It has been proven in many populations that the genetic polymorphism of CYP2C19 has influence on the pharmacokinetic and or pharmacodynamics of this drug and resulting in high inter-individual variability in the treatment outcomes. As CYP2C19 genetic polymorphism is highly prevalent among the Asian population, the influence of the same on the pharmacokinetics and; thereby, the pharmacodynamics of clopidogrel needs more attention. Using the pharmacogenetic information for drug therapy could help overcome these issues and to optimize the dosage regimen of clopidogrel, this review advocates the precision medicine approach for reducing the clopidogrel resistance and adverse cardiovascular events.

Clinical outcomes and predictive model of platelet reactivity to clopidogrel after acute ischemic vascular events

BACKGROUND

High on-treatment platelet reactivity (HTPR) has been suggested as a risk factor for patients with ischemic vascular disease. We explored a predictive model of platelet reactivity to clopidogrel and the relationship with clinical outcomes.

METHODS

A total of 441 patients were included. Platelet reactivity was measured by light transmittance aggregometry after receiving dual antiplatelet therapy. HTPR was defined by the consensus cutoff of maximal platelet aggregation >46% by light transmittance aggregometry. CYP2C19 loss-of-function polymorphisms were identified by DNA microarray analysis. The data were compared by binary logistic regression to find the risk factors. The primary endpoint was major adverse clinical events (MACEs), and patients were followed for a median time of 29 months. Survival curves were constructed with Kaplan-Meier estimates and compared by log-rank tests between the patients with HTPR and non-HTPR.

RESULTS

The rate of HTPR was 17.2%. Logistic regression identified the following predictors of HTPR: age, therapy regimen, body mass index, diabetes history, CYP2C192, or CYP2C193 variant. The area under the curve of receiver operating characteristic for the HTPR predictive model was 0.793 (95% confidence interval: 0.738-0.848). Kaplan-Meier analysis showed that patients with HTPR had a higher incidence of MACE than those with non-HTPR (21.1% vs. 9.9%; χ = 7.572, P = 0.010).

CONCLUSIONS

Our results suggest that advanced age, higher body mass index, treatment with regular dual antiplatelet therapy, diabetes, and CYP2C192 or CYP2C193 carriers are significantly associated with HTPR to clopidogrel. The predictive model of HTPR has useful discrimination and good calibration and may predict long-term MACE.

Between a rock and a hard place: a high-risk patient with resistance to multiple P2Y12 antagonists

Impaired response to P2Y12 receptor antagonists, such as clopidogrel and prasugrel, can have devastating consequences for patients that require prolonged or indefinite therapy with these agents, including those with a left ventricular assist device (LVAD). While loss-of-function (LOF) alleles in CYP2C19 have been elucidated as contributing to high on treatment platelet reactivity (HTPR) during clopidogrel therapy, genetic variations in the metabolic pathway of prasugrel have not been shown to elicit this same effect. Moreover, limited studies have assessed the effect of coexisting genetic variations in pharmacokinetic and pharmacodynamic pathways. Herein, we report a left ventricular assist device patient exhibiting high on treatment platelet reactivity during clopidogrel and prasugrel therapy. Genotyping revealed variants in pharmacokinetic (CYP2B6), and pharmacodynamic pathways, with multiple variants in P2Y12, the target receptor.

P2RY12:rs7637803 TT variant genotype increases coronary artery aneurysm risk in Kawasaki disease in a southern Chinese population

BACKGROUND

Activated-platelet increases the risk of thrombosis in Kawasaki disease (KD) patients with a coronary artery aneurysm (CAA). The ADP pathway is one of the platelet activation and aggregation pathways. The P2RY12 gene encodes the ADP receptor that is highly concentrated on platelets. However, few studies have reported on P2RY12 in relation to KD susceptibility with or without CAA.

METHODS

We recruited 1335 healthy controls and 776 KD patients, including 103 with CAA, and selected five P2RY12 polymorphisms: rs9859538, rs1491974, rs7637803, rs6809699 and rs2046934. The present study focused on the relationship between the P2RY12 polymorphisms and KD with or without CAA.

RESULTS

Among all of the selected polymorphisms, single-locus analysis showed no significant association between the P2RY12 polymorphism and KD susceptibility. However, we found a significant relationship between rs7637803 and CAA risk in KD patients [CT versus CC: odds ratio (OR) = 0.41, 95% confidence interval (CI) = 0.22-0.75; p = 0.0041; TT versus CC: OR = 2.90, 95% CI = 1.12-7.46; p = 0.0276]. Stratification analysis by age in KD patients indicated that the rs7637803 TT genotype increased CAA formation risk among children aged (OR = 3.90, 95% CI = 1.42-10.69; p = 0.0081) and increased the onset risk of CAA in males (OR = 6.28, 95% CI = 2.01-19.65; p = 0.0016). The combined effect of the five selected P2RY12 risk genotypes with the KD patients compared to non-mutated P2RY12 genotypes (score: 0) showed that patients with P2RY12 genotype polymorphisms (score: 1-5) had a significantly increased CAA risk (p = 0.0086). Stratification analysis for the severity of CAA found that the rs7637803 TT genotype reduced giant CAA (GCAA) risk (OR = 4.60, 95% CI = 1.70-12.41; p = 0.0026).

CONCLUSIONS

The results of the present study indicate that the P2RY12 rs7637803 genotype might be used as a biomarker to predict the occurrence of GCAA.

CYP2C19 and ABCB1 genetic polymorphisms correlate with the recurrence of ischemic cardiovascular adverse events after clopidogrel treatment

BACKGROUND

This study was aimed to investigate the correlation between CYP2C19 and ABCB1 polymorphisms and the recurrence of ischemic cardiovascular adverse events in patients with coronary artery disease treated with clopidogrel.

METHODS

A total of 168 patients with coronary heart disease who underwent PCI operation and received clopidogrel treatment were enrolled. Dual antiplatelet therapy was applied to the treatment of patients for 2 years. Thromboelastography was used to test the efficiency of blood coagulation. Polymerase chain reaction (PCR) was used to detect CYP2C19 and ABCB1 3435CT polymorphisms. One-year follow-up visit was carried out to record the incidence of cardiovascular adverse events after drug-eluting stent implantation was inset.

RESULTS

Follow-up visit results suggested that the patients with high on-treatment platelet reactivity (HPR) had a higher recurrence rate of cardiovascular adverse events after PCI operation and clopidogrel treatment. Gene polymorphism testing results indicated that patients with CYP2C19*3 had a significantly higher incidence of HPR, whereas CYP2C19*2 and ABCB1 3435CT were not significantly correlated with HPR. Multivariable logistic regression analysis showed that CYP2C19*3 might be an independent predictive factor of post-PCI HPR. In addition, CYP2C19*3 as well as post-PCI HPR could function as independent predictive factors of cardiovascular adverse events.

CONCLUSION

CYP2C19*3 polymorphism could be an important predictive factor of HPR and ischemic cardiovascular adverse events after clopidogrel treatment.

CYP2C19*17 protects against metabolic complications of clozapine treatment

OBJECTIVES

Clozapine (CZ) is the most effective drug for managing treatment-resistant schizophrenic disorders. Its use has been limited due to adverse effects, which include weight gain and new-onset diabetes, but the incidence of these varies between patients.

METHODS

We investigated 187 Clozapine Clinic patients (of whom 137 consented for genotyping) for the presence of CYP2C19*17 and its association with CZ and norclozapine (NCZ) levels, and clinical outcomes.

RESULTS

Thirty-nine percent of genotyped patients were carriers of the CYP2C 19*17 polymorphism. This group demonstrated significantly higher NCZ serum levels, and significantly lower fasting glucose (5.66 ± 1.19 vs 6.72 ± 3.01 mmol/l, P = 0.009) and Hb1Ac (35.36 ± 4.78 vs 49.40 ± 20.60 mmol/mol, P = 0.006) levels compared to non-carriers of this polymorphism. CZ-treated patients with CYP2C19*17/*17 had a significantly lower prevalence of diabetes as well as a higher likelihood of clinical improvement of their schizophrenia, compared to those without this polymorphism (P = 0.012 and P = 0.031, respectively).

CONCLUSIONS

Our data suggest that CYP2C19*17 ultra-rapid-metaboliser status is a protective factor against the development of diabetes during clozapine treatment, and increases the likelihood of improvement in schizophrenia. The role of NCZ in treatment response and side effects, including metabolic syndrome, warrants further pharmacogenetic, pharmacokinetic and pharmacodynamic studies.

Distribution of CYP2C19 polymorphisms in Mongolian and Han nationals and the choice of specific antiplatelet drugs

Background Individualized medication reviews may improve our understanding of the distribution of CYP2C19 polymorphisms in ethnic populations. Objective To evaluate differences in CYP2C19 gene polymorphisms between Mongolian and Han nationals and determine the effect of adjustments of antiplatelet treatments according to the genetic profile in patients undergoing percutaneous coronary intervention (PCI). Setting Prospective, observational, single-center study. Methods 397 patients diagnosed with acute coronary syndrome were enrolled. Additionally, 186 patients undergoing PCI were given different treatments according to their CYP2C19 genotypes. Patients with the genotype of an extensive metabolizers (EMs; *1/*1) were co-administered aspirin 100 mg/day and clopidogrel 75 mg/day, following a loading dose of 300 mg; intermediate metabolizers (IMs; e.g., *1/*2 and *1/*3) and poor metabolizers (PMs; e.g., *2/*2 and *2/*3) were administered a loading dose of 180 mg ticagrelor, followed by a maintenance dose of 90 mg twice a day. Results In Mongolians, 60.79% of patients were EMs, which was significantly higher than that in Han nationals (P = 0.002). In Han individuals, 62.14% of patients were IMs and PMs, which was significantly higher than that in Mongolians (P < 0.05). Three patients died, and the frequency of adverse events during follow-up was significantly higher in patients given conventional treatment than in patients given tailored treatment (P = 0.039). However, differences in metabolism subtypes did not affect the incidence of adverse reactions. Conclusions There were differences in CYP2C19 polymorphisms between Mongolians and Hans. Effective, safe therapy was achieved by tailoring antiplatelet drug therapy based on genotype.