Effect of cytochrome p450 polymorphisms on platelet reactivity after treatment with clopidogrel in acute coronary syndrome

Genetic polymorphisms of cytochrome P450 (CYP) isoforms may promote variability in platelet response to clopidogrel. This study was conducted to analyze, in 603 patients with non-ST elevation acute coronary syndromes, the effect of CYP3A4, CYP3A5, and CYP2C19 gene polymorphisms on clopidogrel response and post-treatment platelet reactivity assessed by adenosine diphosphate (ADP)-induced platelet aggregation, vasodilator-stimulated phosphoprotein phosphorylation index, and ADP-induced P-selectin expression. The CYP2C19*2 polymorphism was significantly associated with ADP-induced platelet aggregation, vasodilator-stimulated phosphoprotein phosphorylation index, and ADP-induced P-selectin expression in recessive (p <0.01, p <0.007, and p <0.06, respectively) and codominant (p <0.08, p <0.0001, and p <0.009, respectively) models, but the CYP3A4*1B and CYP3A5*3 polymorphisms were not. The CYP2C19*2 allele carriers exhibited the highest platelet index levels in multivariate analysis (p = 0.03). After covariate adjustment, the CYP2C19*2 allele was more frequent in clopidogrel nonresponders, defined by persistent high post-treatment platelet reactivity (ADP-induced platelet aggregation >70%; p = 0.03). In conclusion, the present data suggest that the CYPC19*2 allele influences post-treatment platelet reactivity and clopidogrel response in patients with non-ST elevation acute coronary syndromes.     

Cytochrome P450 2C19 loss-of-function polymorphism is a major determinant of clopidogrel responsiveness in healthy subjects

The capacity of clopidogrel to inhibit ADP-induced platelet aggregation shows wide intersubject variability. To determine whether frequent functional variants of genes coding for candidate cytochrome P450 (CYP) isoenzymes involved in clopidogrel metabolic activation (CYP2C19*2, CYP2B6*5, CYP1A2*1F, and CYP3A5*3 variants) influence the platelet responsiveness to clopidogrel, we conducted a prospective pharmacogenetic study in 28 healthy white male volunteers treated for 7 days with clopidogrel 75 mg/d. We observed that pharmacodynamic response to clopidogrel was significantly associated with the CYP2C19 genotype. Twenty of the subjects were wild-type CYP2C19 (*1/*1) homozygotes, while the other 8 subjects were heterozygous for the loss-of-function polymorphism CYP2C19*2 (*1/*2). Baseline platelet activity was not influenced by the CYP2C19 genotype. In contrast, platelet aggregation in the presence of 10 muM ADP decreased gradually during treatment with clopidogrel 75 mg once daily in *1/*1 subjects, reaching 48.9% +/- 14.9% on day 7 (P < .001 vs baseline), whereas it did not change in *1/*2 subjects (71.8% +/- 14.6% on day 7, P = .22 vs baseline, and P < .003 vs *1/*1 subjects). Similar results were found with VASP phosphorylation. The CYP2C19*2 loss-of-function allele is associated with a marked decrease in platelet responsiveness to clopidogrel in young healthy male volunteers and may therefore be an important genetic contributor to clopidogrel resistance in the clinical setting.     

Usefulness of high clopidogrel maintenance dose according to CYP2C19 genotypes in clopidogrel low responders undergoing coronary stenting for non ST elevation acute coronary syndrome

The cytochrome P450 (CYP) 2C19*2 loss-of-function allele has been associated with impaired clopidogrel response and worse prognosis in clopidogrel-treated patients. The benefit of tailored therapy according to platelet function test results remains unclear, and the potential effect of genotypes on this benefit has not been addressed in unstable patients. The present study was designed to evaluate the benefit of tailored therapy with a higher maintenance dose according to CYP2C19 genotypes in patients identified as nonresponders who underwent percutaneous coronary intervention for non-ST-segment elevation acute coronary syndromes. Three hundred forty-six consecutive patients were enrolled and received a loading dose of 600 mg, including 86 *2 carriers (13 homozygotes and 73 heterozygotes) and 260 *2 noncarriers. Clopidogrel response, assessed with platelet reactivity index vasoactive-stimulated phosphoprotein, was significantly affected by genotype, with lower clopidogrel response in CYP2C19*2 allele carriers (p = 0.01). Accordingly, the rate of clopidogrel nonresponse was higher in CYP2C19*2 allele carriers (53% vs 41%, p = 0.04). All clopidogrel nonresponders (n = 151), including 105 *2 noncarriers and 46 *2 carriers, received high 150-mg clopidogrel maintenance doses at discharge to overcome initial low response. After 1 month, high maintenance doses overcame clopidogrel low response in only 44% of the whole population and significantly less frequently in *2 carriers than in noncarriers (28% vs 50%, p = 0.01). In conclusion, higher clopidogrel maintenance doses were able to overcome clopidogrel low response in fewer than half of clopidogrel low responders who underwent percutaneous coronary intervention for non-ST-segment elevation acute coronary syndromes. The benefit of this tailored therapy was significantly reduced in CYP2C19*2 carriers. Therefore, these patients might require alternative strategies with new P2Y?? blockers.     

Personalized Antiplatelet Therapy: Review of the Latest Clinical Evidence

P2Y12-ADP receptor antagonist use has been critical in the development of percutaneous coronary intervention, dramatically reducing the rate of early stent thrombosis. However, it recently was observed that a significant proportion of patients do not achieve optimal platelet reactivity inhibition after clopidogrel loading dose. The large interindividual variability in clopidogrel responsiveness is related to several factors, including the genetic polymorphism of hepatic cytochrome P450 2C19 (CYP2C19*2), which recently has been highlighted by a warning from the U.S. Food and Drug Administration. Of importance, patients exhibiting reduced clopidogrel metabolism and/or low clopidogrel responsiveness (ie, high on-treatment platelet reactivity) have an increased rate of thrombotic events after percutaneous coronary intervention. This review summarizes the current knowledge on this important clinical issue. While the future of genetic testing remains undetermined, several trials are underway to demonstrate the potential utility of platelet reactivity testing with P2Y12-ADP receptor antagonists.     

Meta-analysis of cytochrome P450 2C19 polymorphism and risk of adverse clinical outcomes among coronary artery disease patients of different ethnic groups treated with clopidogrel

Loss-of-function (LOF) variants of cytochrome P450 2C19 (CYP2C19) have been hypothesized to be associated with lesser degrees of platelet inhibition and increased risk for recurrent ischemic events in patients with coronary artery disease on clopidogrel therapy; however, studies from Western countries have yielded mixed results. We aimed to assess the impact of CYP2C19 LOF variants on clinical outcomes from different ethnic groups. Sixteen prospective cohort studies including 7,035 patients carrying ≥ 1 CYP2C19 LOF allele and 13,750 patients with the wild-type genotype were included in this meta-analysis. Carriers of ≥ 1 CYP2C19 LOF allele were at significantly higher risk for adverse clinical events compared to noncarriers during clopidogrel therapy (odds ratio [OR] 1.42, 95% confidence interval [CI] 1.13 to 1.78). The summary OR showed a significant association between CYP2C19 LOF variants and an increased risk of cardiac death (OR 2.18, 95% CI 1.37 to 3.47), myocardial infarction (OR 1.42, 95% CI 1.12 to 1.81), and stent thrombosis (OR 2.41, 95% CI 1.76 to 3.30). Stratified analysis by ethnicity of study population suggested higher odds of adverse clinical events in the Asian population with LOF variants of CYP2C19 (OR 1.89, 95% CI 1.32 to 2.72) compared to Western populations (OR 1.28, 95% CI 1.00 to 1.64). In conclusion, carrier status for LOF CYP2C19 is associated with an increased risk of adverse clinical events in patients with coronary artery disease on clopidogrel therapy despite differences in clinical significance according to ethnicity.     

Clinical Impact of Genetically Determined Platelet Reactivity

Dual antiplatelet therapy with aspirin and clopidogrel dramatically reduced the rate of major adverse cardiac events following percutaneous coronary intervention. Clopidogrel is a prodrug which requires a two-step hepatic biotransformation thanks to the cytochrome P450 (CYP450) enzyme system. Genetic polymorphism of CYP450 system (e.g., CYP2C19*2) responsible for altered clopidogrel metabolism is a major cause of high on-treatment platelet reactivity (HTPR), which translates into thrombotic events in stented patients. Studies demonstrated that HTPR could be overcome in poor metabolizers thanks to increased loading doses or maintenance doses of clopidogrel or with the use of more potent antiplatelet agents such as prasugrel. Other genetic polymorphisms have also been correlated with HTPR: ABCB1, ATP2B2, and TIAM2. Large-scale randomized trials with clinical endpoints remain necessary to determine the optimal antiplatelet therapy in patients carrying genetic polymorphism associated with HTPR and thrombotic events.     

Near patient anti-platelet response testing over time and gene analysis in patients admitted with acute coronary syndromes

We sought to assess the relationships between platelet reactivity at different time points, CYP2C19*2 and ABCB1 status and clinical outcomes in patients with acute coronary syndromes (ACS). Anti-platelet response to clopidogrel was studied prospectively using the VerifyNow (VN) P2Y₁₂ assay at the time of angiography and at 30 days post procedure in 151 patients admitted with ACS who underwent percutaneous coronary intervention (PCI). Troponin T levels were measured at angiography and 16–24 hour following PCI. DNA was extracted and the presence of CYP2C19*2 allele and ABCB1 polymorphisms were determined. Adverse cardiovascular and cerebral events (ACCE) were assessed at 12 months. High VN P2Y12 response at angiography was associated with a greater peri-procedural rise in troponin T, but not ACCE. However, VN P2Y₁₂ response measured at 30 days was associated with ACCE (p?=?0.017). CYP2C19*2 status was associated with higher VN P2Y12 response at angiography (p?<?0.0001) and 30 days (p?=?0.006) but not ACCE. Near-patient testing for clopidogrel response was associated with subsequent ACCE when performed 30 days following PCI, but not at angiography.     

Clopidogrel Resistance: case reports of CYP2C19 gene variants in suspected coronary stent thrombosis

Clopidogrel is a widely used anti-platelet agent for the prevention of arterial thrombosis. Clopidogrel is administered as a pro-drug and metabolised to its active metabolite by the hepatic cytochrome P450 2C19 (CYP2C19) enzyme. The active metabolite is responsible for the anti-platelet activity of clopidogrel. Recent studies demonstrate that single nucleotide polymorphisms, (SNP's), in the gene for CYP2C19 result in significantly reduced production of the active metabolite of clopidogrel. Additional studies demonstrate that patients with SNP's in the CYP2C19 gene, including CYP2C19*2,*3,*4, and *5, have reduced production of the active metabolite of clopidogrel, reduced inhibition of platelet aggregation and increased incidence of coronary, cerebrovascular, and coronary stent thrombosis. We have been interested in determining the CYP2C19 genotype in cases of coronary stent thrombosis whilst on clopidogrel treatment and provide two case reports of coronary stent thrombosis whilst taking clopidogrel with subsequent CYP2C19 genotyping. As patients at risk of atherothrombosis in general, and stent thrombosis in particular, may be receiving or considered for anti-platelet therapy including clopidogrel, genotyping for CYP2C19 SNP's may be of benefit in the selection of appropriate anti-platelet therapy.     

Inhibition of platelet aggregation by prostaglandin E1 (PGE1) in diabetic patients during therapy with clopidogrel and aspirin

Diabetes mellitus (DM) is associated with increased platelet activation and reduced platelet inhibition by clopidogrel. Prostaglandin E1 (PGE1) stimulates adenyl cyclase activity in platelets and increases cyclic AMP concentrations, which inhibit Ca²⁺release and platelet aggregation induced by P2Y1 receptor activation. PGE1 is included in the VerifyNow P2Y12 assay to suppress P2Y1 induced platelet aggregation. We hypothesized that diabetes mellitus may be associated with altered response to PGE1 in subjects treated with clopidogrel. Subjects with established coronary artery disease who were taking clopidogrel 75?mg daily and aspirin for >14 days were enrolled (n?=?96). Diabetic (n?=?34) were compared with non-diabetic subjects (n?=?62). VerifyNow P2Y12 assay and light transmittance aggregometry (LTA) were performed using ADP as agonist with and without addition of PGE1. Genomic DNA was genotyped for common cytochrome P450 (CYP) 2C19 variants using Taqman assays. Residual on-treatment platelet aggregation induced by 20?µM ADP was not significantly different between subjects with and without DM. Addition of 22?nM and 88?nM PGE1 to 20?µM ADP resulted in a significant reduction of maximal platelet aggregation (MPA). Residual LTA platelet aggregation with PGE1 and VerifyNow P2Y12 platelet reactivity were significantly higher in subjects with DM than those without DM and in carriers of CYP 2C19*2 polymorphism. We conclude that an impaired inhibitory response to PGE1 may contribute to the high platelet reactivity phenotype in subjects with DM treated with clopidogrel. Addition of PGE1 to ADP agonist platelet assays may identify subjects with blunted inhibitory response to prostaglandins and result in a higher proportion of subjects with DM being classified as non-responders.     

CYP2C19基因多态性与氯吡格雷抵抗的研究现状

氯吡格雷是目前治疗急性冠状动脉综合征的一种经典抗血小板药物,能降低冠心病患者尤其是支架术后患者的主要不良心血管事件的风险。但是部分患者存在氯吡格雷抵抗。研究认为,氯吡格雷抵抗受多因素影响,CYP2C19基因多态性是最重要的内部因素。CYP2C19*2和CYP2C19*3是亚洲人群最常见类型,CYP2C19基因变异者,氯吡格雷抗血小板效应减弱,不良心血管事件增加。因此,常规检测CYP2C19基因多态性可指导临床上氯吡格雷个性化用药。     

细胞色素P4502C19基因多态性对介入术后服用氯吡格雷冠心病患者临床预后的影响

目的 探讨细胞色素P450(CYP)2C19 681G>A基因多态性对经皮冠状动脉介入治疗(PCI)后服用氯吡格雷冠心病患者临床预后的影响.方法 入选2009年1月1日至8月31日拟行PCI,并在术后服用氯吡格雷12个月的冠心病患者267例.采用MassARRAY时间飞行质谱检测入选患者CYP2C19 681G>A位点.按基因型不同,将患者分为CYP2C19*1/*1组 (n=130)和CYP2C19*2携带组(n=137).观察两组患者术后1年心绞痛复发、紧急血运重建术、急性心肌梗死、支架内血栓形成和死亡的发生情况.结果 两组患者的临床基本资料差异无统计学意义(P>0.05).PCI术后1年,CYP2C19*2携带组紧急血运重建术和联合终点事件的发生率均高于CYP2C19*1/*1组 (分别为7.3%比1.5%和8.0%比2.3%,P均<0.05).两组患者心绞痛复发、急性心肌梗死、支架内血栓形成和死亡的发生率差异均无统计学意义(P均>0.05).CYP2C19*2携带组随访1年的累积联合终点事件发生风险是CYP2C19*1/*1组的3.59倍(HR=3.59,95%CI:1.02～12.87,P<0.05).结论 CYP2C19 681G>A基因多态性可能是影响PCI术后服用氯吡格雷冠心病患者临床预后的因素.

Abstract：

Objective To investigate the impact of cytochrome P450 (CYP) 2C19 681G>A polymorphism on long-term prognosis of clopidogrel-treated Chinese patients after percutaneous coronary intervention (PCI).Methods Between January 1, 2009 and August 31,2009, 267 patients with coronary heart disease who received PCI and treated with clopidogrel for 12 months were enrolled. CYP2C19*2 was detected by MALDI-TOF MS and patients were grouped into CYP2C19*1/*1(n=130) and CYP2C19*2 carriers group (n=137). Follow-up was 12 months. The primary endpoint was angina recurrence, urgent coronary revascularization, acute myocardial infarction, stent thrombosis, death and the combined end points. Results Baseline data were similar between two groups (P>0.05).Urgent coronary revascularization and the combined end points occurred more frequently in CYP2C19*2 carriers than in CYP2C19*1/*1 patients (7.3% vs. 1.5% and 8.0% vs. 2.3% respectively,all P<0.05). But incidence of angina recurrence, acute myocardial infarction, stent thrombosis and death was similar between two groups (all P>0.05).Hazard risk of 1 year cumulative survival of CYP2C19*2 carriers group was significantly higher than CYP2C19*1/*1 group after PCI (HR=3.59, 95%CI: 1.02-12.87, P<0.05). Conclusion CYP2C19 681G>A polymorphism is a determinant of prognosis in coronary heart disease patients receiving chronic clopidogrel treatment after PCI.     

不同的质子泵抑制剂与氯吡格雷相互作用的研究进展

大量研究表明阿司匹林和氯吡格雷联合抗血小板可以降低急性冠状动脉综合征及冠状动脉支架植入术后复发心血管事件的概率。但由于联合抗血小板治疗会增加出血的风险,所以目前临床推荐加用质子泵抑制剂以预防胃肠道溃疡和出血。氯吡格雷和质子泵抑制剂均通过细胞色素P450同工酶系统代谢,质子泵抑制剂通过竞争性抑制细胞色素P450同工酶CYP2C19,而降低氯吡格雷的抗血小板活性,增加复发心血管事件的概率。最近的研究发现不同的质子泵抑制剂影响程度不同,泮托拉唑和埃索美拉唑对氯吡格雷作用影响较小,而奥美拉唑、雷贝拉唑和兰索拉唑对氯吡格雷的抗血小板活性抑制作用较大。     

细胞色素P4502 C19快代谢基因型缺血性卒中患者氯吡格雷抵抗的影响因素分析

目的 探讨细胞色素P4502C19(CYP2C19)快代谢基因型缺血性卒中患者氯吡格雷抵抗的影响因素.方法 回顾性连续纳入CYP2C19快代谢基因型(CYP2C19*1/*1)缺血性卒中住院患者204例,均于确诊后连续服用氯吡格雷75 mg/d,共7 d,第8天晨起空腹抽取静脉血,2 h内完成血栓弹力图血小板图的检测....     

Genetic determinants of on-clopidogrel high platelet reactivity

Clopidogrel has been used (alone or in association with aspirin) to prevent vascular complications in atherothrombotic patients, to prevent stent thrombosis (ST) in patients undergoing percutaneous coronary intervention (PCI) and as a long-term prevention of cardiovascular and cerebrovascular events. Unfortunately, it is important to note that there are a number of patients who, during clopidogrel therapy, show and maintain a high platelet reactivity (PR), similar to that observed before the start of antiplatelet therapy. Clopidogrel pro-drug is absorbed in the intestine and this process is influenced by P-glycoprotein-1 (P-GP). Its conversion into 2-oxo clopidogrel is regulated by cytochromes (CYP) called CYP2C19, CYP2B6 and CYP1A2. Whereas, the final transformation into the active metabolite is regulated by CYP called CYP2C19, CYP2C9, CYP2B6, CYP3A4, CYP3A5 and, as recently emerged, by the glycoprotein paraoxonase-1 (PON1). The genes encoding these enzymes are characterized by several polymorphisms. Some of these are able to modify the activity of proteins, reducing the concentration of active metabolite and the values of on-clopidogrel PR. Only one gene polymorphism (CYP2C19*17) increases the clopidogrel metabolization and so the clopidogrel-induced platelet inhibition. Several studies have clearly associated these gene polymorphisms to both ischemic and bleeding complications in patients receiving dual antiplatelet therapy. The aim of this review is to describe the principal gene polymorphisms influencing on-clopidogrel PR and their relationship with long-term clinical outcome.     

Factors determining clinical effectiveness of clopidogrel and prognosis of patients with stable ischemic heart disease

Aim of the study was to elucidate genetic and drug factors affecting efficacy of clopidogrel in patients with ischemic heart disease - inhabitants of central region of Russian Federation. We included 399 patients with IHD (79% men, mean age 58.3+/-9 years) receiving long term therapy with clopidogrel 75 mg/day (during stable manifestations of the disease) or 75-150 mg/day in combination with aspirin (in relation with recent elective percutaneous interventions). We studied carriage of polymorphisms of genes controlling intestinal absorption of clopidogrel (ABCB1 C3435T), activation of clopidogrel in the liver (CYP2C19 *1 *2), and also registered concomitant administration of proton pump inhibitors (PPI). Then we determined relationship of these factors to development of vascular complications (vascular death/myocardial infarction/requirement in revascularization) during 18 months followup. Among studied genetic factors carriage of allele variants CYP2C19 *1/*2 and *2/* (found in 25.5 and 1.8% of patients, respectively), possessed prognostic significance. In the group of clopidogrel monotherapy carriage of at least one *2 allele was associated with increased rate of vascular complications (33.3% vs. 11.3%) including thrombotic complications (27.7% vs. 3.2%; =0.01). In patients receiving 75 mg/day of clopidogrel in combination with aspirin total rate of thrombotic complications as well as of all adverse unfavorable outcomes was higher in *2 carriers compared with wild type homozygotes (14.0% vs.8.7% and 21.0% vs. 15.8%, respectively). In patients receiving double dose clopidogrel in combination with aspirin we found no worsening of outcomes associated with CYP2C19*2 carriage. In the multifactorial risk model independent predictors of vascular complications turned out to be CYP2C19 *2/*2 homozygosity (RR 4.9; =0.02) and concomitant PPI administration ( 1.8; p=0.05).     

CYP2C19基因检测在氯吡格雷治疗中的临床意义

氯吡格雷对血小板抑制作用具有个体化差异。接受标准化氯吡格雷治疗的患者仍然发生了不良心血管事件。CYP2C19基因多态性是较为公认的内在遗传因素。大量研究证实CYP2C19功能缺失基因与心血管事件风险增加相关,尤其是支架内血栓事件。替格瑞洛和替卡格雷是可能的替换药物。本文围绕CYP2C19基因多态性及临床应用做一综述。     

氯吡格雷药物基因组学及个体化治疗研究进展与展望

通过与阿司匹林联合应用,氯吡格雷已经成为治疗急性冠脉综合征和预防经皮冠状动脉介入术后支架内血栓形成和再发缺血事件的经典口服抗血小板药物。尽管如此,氯吡格雷抗血小板的反应性和疗效存在显著的个体间差异。近年来的研究证实,除临床环境因素外,遗传变异是导致氯吡格雷抗血小板反应性个体间差异的重要因素之一。多项大规模临床药物基因组学研究发现,参与氯吡格雷代谢的关键酶—CYP2C19功能缺失型等位基因与氯吡格雷治疗期间高血小板反应性及心血管一级缺血终点事件的发生密切相关。另外,与氯吡格雷代谢相关的其他基因变异型也被证实可能与氯吡格雷抗血小板反应性及不良心血管事件相关。在此基础上,利用药物基因组学基因型检测指导氯吡格雷个体化抗血小板治疗,可能部分克服氯吡格雷治疗期间的高血小板反应性,但研究结果之间仍存在争议,尚需深入研究以提供更有力的证据。除此之外,未来有必要进一步深入研究基因型检测联合血小板功能监测共同指导氯吡格雷抗血小板个体化治疗的效果。     

Differential Impact of Clinical and Genetic Factors on High Platelet Reactivity in Patients with Coronary Artery Disease Treated with Clopidogrel and Prasugrel

Aim: High platelet reactivity (HPR) is associated with increased risks of thrombotic events in patients with coronary artery disease. The recently developed ABCD-GENE score identified five clinical and genetic factors (age, body mass index, chronic kidney disease, diabetes, and the CYP2C19 loss-of-function allele) for HPR, although the significance of various stages of each factor is unclear. Methods: Four prospective studies were pooled, in which platelet reactivity was measured using the VerifyNow assay with clopidogrel and prasugrel; genotyping of CYP2C19 was also performed. Each component of the ABCD-GENE score was divided into three subcategories. VerifyNow P2Y12 reactivity units ＞208 were defined as HPR. Results: A total of 184 patients were included, of which 111 (60%) and 51 (28%) had HPR with clopidogrel and prasugrel. Chronic kidney disease had an impact on HPR on both clopidogrel and prasugrel, whereas the impact of diabetes was more evident in patients treated with prasugrel. Although the number of CYP2C19 loss-of-function alleles was clearly associated with a likelihood of HPR with clopidogrel, P2Y12 reactivity units with prasugrel treatment were also significantly and progressively higher in patients with more CYP2C19 loss-of-function alleles. Conclusions: Clinical and genetic factors had a differential effect on a P2Y12 inhibitor reactivity with clopidogrel and prasugrel in patients with coronary artery disease. The severity of the factors also had a different impact on HPR.     

CYP2C19酶与氯吡格雷抵抗

冠状动脉介入支架术后病人常规抗血小板的治疗,目前阿司匹林与氯吡格雷联合运用已成为支架术后抗血小板的常规诊疗方法。氯吡格雷需经CYP2C19代谢生成活性产物而发挥抗血小板聚集作用。但由于氯吡格雷抵抗发生支架内血栓事件逐渐增多,这一现象也受到人们的关注,冠状动脉介入支架术后病人服用氯吡格雷支架内血栓发生率与CYP2C19基因多态性是否有相关性。现就其研究现状做一综述。     

Common sequence variations in the P2Y12 and CYP3A5 genes do not explain the variability in the inhibitory effects of clopidogrel therapy

The efficacy of the platelet P2Y12 receptor antagonist clopidogrel, which undergoes cytochrome-mediated metabolism to its active form, shows marked inter-individual variability. We investigated whether polymorphic variations in the P2Y12 gene, which have been linked to platelet aggregation phenotypes, or the cytochrome P450 3A5 gene 6986G > A polymorphism, which largely determines CYP3A5 expression, influence the response to clopidogrel therapy. Fifty-four patients listed for elective percutaneous coronary intervention were studied using ADP-induced optical aggregometry, whole-blood single platelet counting (WBSPC) aggregometry, and flow-cytometric analysis of platelet P-selectin expression and platelet-monocyte conjugate formation. Platelet reactivity was measured at baseline, 4 h post clopidogrel 300 mg, and 10 and 28 days following clopidogrel 75 mg daily. A further 55 patients were studied using ADP-induced WBSPC at baseline and 4 h post clopidogrel 600 mg. Patients were genotyped for P2Y12 haplotype and the CYP3A5 6986G > A single nucleotide polymorphism. Neither genotype was found to significantly influence the inhibition of platelet responses by either clopidogrel regimen. In conclusion, common sequence variations within the P2Y12 and CYP3A5 genes do not contribute any major effect to the inter-patient variability in clopidogrel efficacy.