Genetic determinants of platelet response to clopidogrel

Antiplatelet agents are the mainstay treatment in the prevention and management of atherothrombotic complications. However, a substantial interpatient variability in response to clopidogrel has been reported. Furthermore, patients with coronary artery disease and lesser platelet inhibition in response to clopidogrel are at increased risk for cardiovascular events. Clopidogrel after absorption requires two-step oxidation by the hepatic cytochrome P450 to generate its active metabolite. Polymorphisms of genes encoding the cytochrome enzymes and P-glycoprotein involved in clopidogrel absorption are regarded as major determinants of the interindividual variability in the clopidogrel-induced platelet inhibition. In our review we discuss the prevalence and clinical significance of various alleles of the genes: CYP2C19 and ABCB1 in the setting of coronary artery disease. Allele CYP2C19*2 is associated with excess of ischaemic events including myocardial infarction and stent thrombosis. On the other hand, CYP2C19*17 allele poses a serious threat of bleeding. Data concerning the prognostic value of genetic variant 3435C→T of ABCB1 remain inconclusive.     

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。     

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.     

急性冠脉综合征PCI术后患者CYP2C19*2、CYP2C19*3基因多态性与氯吡格雷抵抗及临床预后的关系

目的 探讨急性冠脉综合征经皮冠状动脉介入治疗（Percutaneous Coronary Intervention,PCI）术后患者CYP2C19*2、CYP2C19*3基因多态性与氯吡格雷抵抗及临床预后的关系。方法 入选310例急性冠脉综合征行PCI术的患者,采用生物传感器基因芯片技术检测所有患者CYP2C19*2、CYP2C19*3基因型,根据基因型分为强代谢组（未携带突变基因,681GG/636GG）,中代谢组（携带一个突变基因,681GA/636GG,681GG/636GA）,弱代谢组（携带两个突变基因,681GA/636GA,681AA/636GG,681GG/636AA）。采用全流式细胞术定义氯吡格雷抵抗。分析各组之间氯吡格雷抵抗发生率的差异。观察各组12个月随访支架内血栓与心血管事件发生率。结果 强代谢组、中代谢组、弱代谢组分别为137例（44.2%）、134例（43.2%）、39例（12.6%）,三组之间氯吡格雷抵抗发生率有统计学差异。12个月随访中弱代谢组联合心血管不良事件发生率显著高于强代谢组(P<0.05),其中非致死心梗和支架内血栓发生率显著高于强代谢组(P<0.05),而死亡及再次血运重建率两组比较差异无统计学意义(P>0.05);中弱代谢组再次住院率也显著高于强代谢组。结论 急性冠脉综合征患者PCI术后CYP2C19*2、CYP2C19*3基因变异氯吡格雷抵抗发生率更高,支架内血栓及心血管不良事件发生率明显升高。     

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。     

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。     

细胞色素P450 2C19多态性与对氯吡格雷的反应性研究进展

氯吡格雷是一种无活性的前体药物,进入体内后需要通过细胞色素P450（主要是细胞色素P450 2C19即CYP2C19）氧化为活性代谢物而发挥其抗血小板作用。越来越多的研究发现CYP2C19某些基因多态性（主要是细胞色素P450＊2）与氯吡格雷的活性代谢产物减少,血小板抑制程度减轻,及主要不良心血管事件及支架内血栓增加有关。现就细胞色素P450多态性对氯吡格雷的药代动力学、药效动力学与临床终点事件的影响,及对细胞色素P450等位基因携带者的处理最新研究进展进行综述。     

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.     

细胞色素P450 2C19*2基因多态性联合钙通道阻滞剂与冠状动脉支架内血栓形成的相关性

目的:探讨经皮冠状动脉介入术(PCI)后接受氯吡格雷治疗的患者中,细胞色素P450 2C19(CYP2C19)*2基因多态性(681A)与支架内血栓形成的相关性,以及服用钙通道阻滞剂(CCBs)与支架内血栓形成的相关性。方法:检测1 738例冠心病PCI术后患者的CYP2C19基因多态性,并将这些患者分为CCBs组和非CCBs组,采用比浊法检测二磷酸腺苷(ADP)途径诱导的血小板最大聚集率(MPAR),比较两组患者MPAR及支架内血栓形成率的差异。结果:19例(2.4%)CYP2C19*2基因型的患者(包括CYP2C19*2/*2或*1/*2)和7例(0.75%)基因型为CYP2C19*1/*1的患者发生了明确的支架内血栓形成;CYP2C19*2基因型患者支架内血栓形成的发生率明显高于CYP2C19野生型纯合子患者(CYP2C19*1/*1)(风险比为4.26,95%可信区间为1.28～9.22,P<0.05);基因型为CYP2C19*1/*1的患者发生支架内血栓形成的风险最低,而基因型为CYP2C19*2/*2的患者支架内血栓形成的风险最高(风险比为0.568,95%可信区间为0.308～2.070,P<0.01);CCBs组和非CCBs组MPAR及支架内血栓形成率差异无统计学意义。结论:PCI术后接受氯吡格雷治疗的冠心病患者中,CYP2C19*2基因型患者支架内血栓形成的风险增加,而服用CCBs不会导致氯吡格雷抗血小板聚集作用减弱以及支架内血栓形成事件增加。     

PCI术后患者的CYP2C19基因型分布及其基因型指导抗血小板治疗的效果

目的:描述中国西北地区汉族人群经皮冠状动脉介入(PCI)术后患者细胞色素P450(CYP2C19)基因多态性分布特点,并评价依据基因型指导PCI术后氯吡格雷抗血小板治疗的效果。方法:1入选2013年1月7月在西京医院心内科行PCI的来自西北地区汉族患者2 117例行CYP2C19基因型检测,根据不同等位基因功能缺失分为快代谢基因型(*1/*1)、中间代谢基因型(*1/*2、*1/*3)和慢代谢基因型(*2/*2、*2/*3、*3/*3);2从上述人群中选择临床资料完整的患者153例,按基因型分为2组:正常代谢组(快代谢基因型,59例)和弱代谢组(中间代谢和慢代谢基因型,94例)。正常代谢组患者术后口服氯吡格雷75 mg/d至1年,而弱代谢组氯吡格雷150 mg/d强化治疗1个月,后75 mg/d至1年抗血小板治疗;于术后1、3、6、9和12个月随访并记录和比较两组间主要不良心脑血管事件(MACE)发生情况。结果:1检测入选的2117例患者基因型结果显示,快代谢基因型(*1/*1)885例,发生率41.80%,中间代谢基因型(*1/*2、*1/*3)971例,发生率45.86%,其中*1/*2占39.16%,*1/*3占6.70%,慢代谢基因型(*2/*2、*2/*3、*3/*3)261例,发生率12.32%。2正常代谢组失訪6例,弱代谢组失訪5例,两组失訪率(9%vs.5%)差异未达到显著水平。正常代谢组和弱代谢组MACE发生率[12.3%(6/59)vs.10.1%(8/94),两组差异也无统计学意义。结论:1入选患者CYP2C19等位基因突变频率发生率高,其中以*1/*2为主,2按基因型采取不同剂量的抗血小板药物后两组MACE发生率差异无统计学意义。     

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.     

A case of subacute thrombosis associated with clopidogrel resistance after implantation of a zotarolimus-eluting stent

A 73-year-old woman was admitted to our hospital with anterior acute myocardial infarction due to subacute thrombosis after coronary stenting with a zotarolimus-eluting stent (ZES), which is a newly developed drug-eluting stent that has been widely used since May 2009 in Japan. Five days before, she underwent implantation with a ZES in the left anterior descending artery due to stable angina pectoris. After stenting, the intravascular ultrasonography showed no malapposition from the proximal to the distal edge of the stent. She received aspirin 100 mg/day and clopidogrel 75 mg/day from 2 weeks before the stent was implanted. When we investigated the single nucleotide polymorphisms of CYP2C19 in this patient, both CYP2C19*2 and CYP2C19*3 were detected, and she was classified as a poor metabolizer. This report is the first to describe subacute stent thrombosis following the implantation of a newly developed ZES in a Japanese patient, which may be related to clopidogrel resistance.     

Laboratory evaluation of clopidogrel responsiveness by platelet function and genetic methods

Clopidogrel is a widely used antiplatelet agent that irreversibly inhibits platelet P2Y12 ADP receptors after conversion to an active metabolite. There are a number of laboratory tests capable of detecting clopidogrel-induced platelet inhibition and published literature correlates suboptimal clopidogrel response to adverse cardiovascular outcomes. Genetic polymorphisms are thought to affect conversion of the prodrug to the active metabolite, and the FDA has recently added a black-box warning to clopidogrel to highlight the effects of these polymorphisms on drug bioavailability and to inform prescribers about the availability of genetic testing. For these reasons, there is growing interest in the use of laboratory tests to monitor patients treated with clopidogrel. This article summarizes the currently available laboratory testing, including platelet function tests and genotyping for CYP2C19 variants.     

The relationship between CYP2C19 polymorphisms and ischaemic and bleeding outcomes in stable outpatients: the CHARISMA genetics study

Aims Clinical trials have established the value of clopidogrel therapy in a wide spectrum of patients with cardiovascular diseases. Both loss- and gain-of-function single nucleotide variants of CYP2C19 genes have been identified that affect clopidogrel metabolism and anti-platelet response. We sought to determine the impact of CYP2C19 polymorphisms on ischaemic and bleeding events. Methods and results A subset of patients from the Clopidogrel for High Atherothrombotic Risk and Ischemic Stabilization, Management, and Avoidance (CHARISMA) trial who consented to genotyping was analysed. Patients with clinically evident cardiovascular disease or multiple risk factors were enrolled in the trial. The rates of ischaemic and bleeding events were compared between carriers and non-carriers of loss-of-function and gain-of-function alleles in patients randomized to clopidogrel vs. placebo. A total of 4819 patients were genotyped and available for the analysis. Carriers of CYP2C19 loss-of-function alleles did not have an increased rate of ischaemic events. However, clopidogrel-treated patients did have a significantly lower rate of any bleeding in carriers: 36.1% (240/665) vs. 42.5% (681/1601) in non-carriers, HR: 0.80, 95% CI: 0.69-0.93, P = 0.003 (genotype/treatment interaction, P-value = 0.023). The CYP2C19 gain-of-function alleles did not affect ischaemic or bleeding endpoints. Conclusion No relationship was seen between CYP2C19 status and ischaemic outcomes in stable patients treated with clopidogrel. There was, however, significantly less bleeding with clopidogrel in carriers of the loss-of-function allele, suggesting less anti-platelet response. Although several prior studies, including mainly stented patients, have emphasized the relationship between CYP2C19 loss-of-function alleles and efficacy of clopidogrel, this study of stable patients establishes a potential link with reduced bleeding complications. Clinical Trial Registration: This study is registered with ClinicalTrials.gov number, NCT00050817.     

CYP2C19基因多态性与氯吡格雷抵抗的研究进展

氯吡格雷是治疗急性冠脉综合征的一种经典抗血小板药物,但是临床观察到部分患者不能从氯吡格雷的治疗中获益,从而提出了氯吡格雷抵抗（CR）的问题。目前研究认为,CR受多因素影响,其中CYP2C19基因的多态性是最重要的内部因素。CYP2C19基因变异者,氯吡格雷的活性代谢产物减少,抗血小板效应减弱,不良心血管事件增加。而CYP2C19＊2和CYP2C19＊3是亚洲人最常见类型,因此,探讨CYP2C19基因的多态性对氯吡格雷疗效的影响具有临床意义。     

Switching from prasugrel to clopidogrel based on Cytochrome P450 2C19 genotyping in East Asian patients stabilized after acute myocardial infarction

To evaluate the pharmacodynamic efficacy of de-escalating P2Y₁₂ inhibition from prasugrel to clopidogrel based on cytochrome P450 (CYP) 2C19 genotyping, we genotyped 50 Korean patients with AMI who underwent percutaneous coronary intervention (PCI) for CYP2C19 *2,*3, or *17 using real-time PCR. They were discharged on prasugrel 10 mg daily. A control group of 48 AMI patients who underwent PCI and were discharged on clopidogrel but did not undergo genotyping was identified retrospectively. Based on genotyping results available at 3 weeks, 12 patients found to have 2 copies of either CYP2C19 *2 or *3 loss of function alleles continued prasugrel while the remaining 38 patients switched to clopidogrel 75 mg daily. The rate of patients within the therapeutic window (TW) of on-treatment platelet reactivity (OPR), 85<P2Y₁₂ reactivity unit (PRU) ≤275, was compared in the genotype-directed cohort before (3 weeks) and after genotype-directed antiplatelet treatment (5 weeks), as well as with the control cohort at 5 weeks. In the genotype-directed group, there was an increase in the proportion of patients within the TW after genotype-directed antiplatelet treatment (48–76%, p=0.007), primarily driven by a decrease of patients with PRU <85 (52–16%, p <0.001). The proportion of patients within the TW was similar between the genotype-guided and control groups (76% vs. 72.9% p=0.726). In conclusion, individualized antiplatelet regimens based on CYP2C19 genotyping may improve likelihood of achieving a TW of OPR compared to fixed dose of prasugrel 10 mg during maintenance periods of AMI in East Asians.     

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.     

氯吡格雷抵抗与基因多态性

氯吡格雷是目前广泛应用于临床的一种抗血小板药,已作为心肌梗死、缺血性卒中和周围血管病的二级预防用药.然而,氯吡格雷的抗血小板聚集效果存在显著的个体差异,很大一部分患者存在抵抗现象.氯吡格雷抵抗的机制尚不完全清楚,基因多态性是氯吡格雷抵抗的一个重要原因,包括ABCB1、CYP2C19、CYP3 A4、CYP3A5、P2Y...     

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。