Pharmacogenomic Impact of CYP2C19 Variation on Clopidogrel Therapy in Precision Cardiovascular Medicine

Effect of cytochrome P450 2C19 (CYP2C19) gene polymorphism and clopidogrel reactivity on long term prognosis of patients with coronary heart disease after PCI

Objective

To investigate the impact of CYP2C19 gene polymorphism on clopidogrel reactivity and its association with long-term clinical outcome in patients with coronary heart disease (CHD) undergoing percutaneous coronary intervention (PCI).

Methods

In total, 675 patients were enrolled. Based on the platelet inhibition rate, patients were categorized into two groups: clopidogrel low responsiveness (CLR) and normal clopidogrel responsiveness (NCR). The CLR group was divided into ticagrelor and clopidogrel group based on the antiplatelet drugs used in the follow-up treatment. Patients were classified into three groups (normal metabolizer, intermediate metabolizer, and poor metabolizer) based on the CYP2C19 genotype. We aimed to evaluate the impact of CYP2C19 gene polymorphism on clopidogrel reactivity. The cumulative rates of 12-month all-cause deaths, major adverse cardiovascular events (MACCEs), and bleeding events were calculated.

Results

CLR was observed in 44.4% of the overall population. Significant differences were observed in the platelet inhibition rate of clopidogrel among the three metabolic genotypes (P < 0.05). At the 12-month follow-up, 13 patients (1.9%) died and 96 patients (14.2%) experienced MACCEs. Patients with CLR (9.6% vs. 11.7% vs. 22.1%, P < 0.05) or poor metabolizer (10.7% vs. 16.4% vs. 22.6%, P = 0.026) experienced a higher rate of MACCEs. A MACCEs risk score between zero and two was calculated. The highest incidence of MACCEs significantly increased with the 2-positive results, and the area under the curve (AUC) was 0.712 (95% CI: 0.650-0.774, P < 0.05). There was no significant difference between the group with a score of one and the occurrence of MACCEs (P > 0.05).

Conclusions

Low response to clopidogrel in CHD patients is correlated with CYP2C19 gene polymorphism. CYP2C19 genotyping combined with platelet reactivity is an independent predictor of 12-months MACCEs in patients with clopidogrel treatment after PCI, which is better than either test alone.

Signatures of Co-evolution and Co-regulation in the CYP3A and CYP4F Genes in Humans

Cytochromes P450 (CYP450) are hemoproteins generally involved in the detoxification of the body of xenobiotic molecules. They participate in the metabolism of many drugs and genetic polymorphisms in humans have been found to impact drug responses and metabolic functions. In this study, we investigate the genetic diversity of CYP450 genes. We found that two clusters, CYP3A and CYP4F, are notably differentiated across human populations with evidence for selective pressures acting on both clusters: we found signals of recent positive selection in CYP3A and CYP4F genes and signals of balancing selection in CYP4F genes. Furthermore, an extensive amount of unusual linkage disequilibrium is detected in this latter cluster, indicating co-evolution signatures among CYP4F genes. Several of the selective signals uncovered co-localize with expression quantitative trait loci (eQTL), which could suggest epistasis acting on co-regulation in these gene families. In particular, we detected a potential co-regulation event between CYP3A5 and CYP3A43, a gene whose function remains poorly characterized. We further identified a causal relationship between CYP3A5 expression and reticulocyte count through Mendelian randomization analyses, potentially involving a regulatory region displaying a selective signal specific to African populations. Our findings linking natural selection and gene expression in CYP3A and CYP4F subfamilies are of importance in understanding population differences in metabolism of nutrients and drugs.

The diversity and clinical implications of genetic variants influencing clopidogrel bioactivation and response in the Emirati population

BACKGROUND

Clopidogrel is a widely prescribed prodrug that requires activation via specific pharmacogenes to exert its anti-platelet function. Genetic variations in the genes encoding its transporter, metabolizing enzymes, and target receptor lead to variability in its activation and platelet inhibition and, consequently, its efficacy. This variability increases the risk of secondary cardiovascular events, and therefore, some variations have been utilized as genetic biomarkers when prescribing clopidogrel.

METHODS

Our study examined clopidogrel-related genes (CYP2C19, ABCB1, PON1, and P2Y12R) in a cohort of 298 healthy Emiratis individuals. The study used whole exome sequencing (WES) data to comprehensively analyze pertinent variations of these genes, including their minor allele frequencies, haplotype distribution, and their resulting phenotypes.

RESULTS

Our data shows that approximately 37% (n = 119) of the cohort are likely to benefit from the use of alternative anti-platelet drugs due to their classification as intermediate or poor CYP2C19 metabolizers. Additionally, more than 50% of the studied cohort exhibited variants in ABCB1, PON1, and P2YR12 genes, potentially influencing clopidogrel's transport, enzymatic clearance, and receptor performance.

CONCLUSIONS

Recognizing these alleles and genotype frequencies may explain the clinical differences in medication response across different ethnicities and predict adverse events. Our findings underscore the need to consider genetic variations in prescribing clopidogrel, with potential implications for implementing personalized anti-platelet therapy among Emiratis based on their genetic profiles.

Thromboelastographic and Gene Polymorphism Bimodality Detection for Dual Antiplatelet Aggregation Therapy in Individuals with Clopidogrel-resistant Symptomatic Intracranial Artery Stenosis

BACKGROUND

Recent research indicates that clopidogrel resistance is connected with a patient's future ischemia risk, hence increasing the likelihood of recurrent ischemic cerebrovascular disease. Thromboelastographic and clopidogrel gene polymorphism testing can be used to see how a person responds to antiplatelet therapy and change the treatment plan accordingly. This may be a good way to make antiplatelet aggregation therapy more effective and safer.

OBJECTIVE

The objective of this study was to investigate the efficacy of dual antiplatelet aggregation therapy in patients with symptomatic intracranial large artery stenosis being resistant to clopidogrel tablets. The thromboelastographic and gene polymorphism bimodality detection techniques were used to analyze the clopidogrel resistance influencing factors.

METHODS

89 patients with symptomatic intracranial large arterial stenosis who were admitted to our hospital from February 2021 to February 2022 were selected, classified as large artery atherosclerotic type by TOAST, and confirmed as having severe intracranial large arterial stenosis (70 % to 99 %) by magnetic resonance angiography (MRA), computed tomographic angiography (CTA), and digital subtraction angiography (DSA). All patients were treated with dual antiplatelet therapy with aspirin and clopidogrel, and thromboelastography and clopidogrel gene polymorphism were monitored 1 week later.

RESULTS

44 of 89 patients were clopidogrel-resistant. Among 44 patients, 20 were ticagrelorresistant and 24 were cilostazol-resistant. Clopidogrel had a resistance rate of 49.4%. The recurrence of ischemic cerebrovascular disease in the three groups was statistically significant (P<0.05) after 3 months of follow-up treatment, but bleeding (intracranial, gastrointestinal, respiratory, urinary, and mucocutaneous) and dyspnea were not. The clopidogrel-resistant group had a higher number of females, as well as higher levels of hypertension, diabetes, and platelet count than the sensitive group (P<0.05), but there was no significant difference in age, smoking, alcohol consumption, previous stroke, glycosylated haemoglobin, creatinine, or low-density cholesterol.

CONCLUSION

Using thromboelastographic and gene polymorphism bimodality detection, we found switching to ticagrelor antiplatelet aggregation therapy as better than switching to cilostazol in patients with symptomatic intracranial large artery stenosis being resistant to clopidogrel tablets. The results may be biased due to the study being a single-centre study and having a limited sample size.

Advances and Perspectives in methods for identifying high platelet reactivity

Antiplatelet therapy is the foundational treatment for the prevention and treatment of coronary and cerebrovascular ischemic events in patients with coronary heart disease, ischemic stroke, and transient ischemic attack (TIA). However, with more and more studies reporting an increased risk of thrombosis in some patients due to poor response to therapeutic agents, the selection of appropriate P2Y12 inhibitors has become a major challenge that needs to be addressed urgently. Currently, commonly used oral P2Y12 inhibitors include clopidogrel, ticagrelor, and prasugrel. Assessing patients' risk factors before the development of treatment regimens by effectively predicting the risk of high platelet reactivity with specific P2Y12 inhibitors in advance to avert the occurrence of major adverse cardiovascular and cerebrovascular events (MACCE) is the key point to the problem. Up to now, methods available for predicting platelet reactivity include genetic testing, platelet function testing, and risk scores. This review provides a summarization of the existent available identification methods and analyzes the advantages and drawbacks of different methods in specific clinical settings, intending to guide the rational clinical application of P2Y12 receptor inhibitors.

Are Community Pharmacists Ready to Deliver Pharmacogenomics Testing Services?

This study assesses the readiness and willingness of community pharmacists in England to deliver the pharmacogenomic (PG) testing service. A survey covering demographics and four key themes including awareness and training, general views and experience, barriers, willingness, and confidence was distributed to community pharmacies in the boroughs of Croydon and Sutton in South London. A total of 51 pharmacists responded to the survey. The study revealed that most respondents had a limited familiarity or understanding of pharmacogenomics (n = 32, 63%). Moreover, on average, around 60% of participants were unable to accurately identify drugs that currently have or could have potentials for PG testing. They indicated that their pharmacogenomic education and training is inadequate, with only 2/51 pharmacists reported receiving relevant training. Time constraints, shortage of staff and lack of knowledge were identified as barriers that could hinder the implementation of PG. Over 60% of respondents expressed willingness to provide PG testing service after receiving adequate training. The study found that currently not all community pharmacists are prepared to provide PG testing services, with newly qualified pharmacists appearing to have an upper hand when it comes to understanding the subject. Therefore, consistent, and uniform training is required to allow community pharmacists with all years of experience to equally contribute to the implementation of PG testing.

Trends in Dual Antiplatelet Therapy Use for Neurointerventional Procedures for the Management of Intracranial Aneurysms

The use of periprocedural dual antiplatelet therapy (DAPT) has significantly evolved along with innovations in the endovascular management of intracranial aneurysms. Historically, aspirin and clopidogrel have been the most commonly employed regimen due to its safety and efficacy. However, recent studies highlight the importance of tailoring DAPT regimens to individual patient characteristics which may affect clopidogrel metabolism, such as genetic polymorphisms. In the present report, a systematic review of the literature was performed to determine optimal antiplatelet use with flow diverting stents, intracranial stents, intrasaccular devices, and stent-assisted coiling. Studies were analyzed for the number of aneurysms treated, DAPT regimen, and any thromboembolic complications. Based on inclusion criteria, 368 studies were selected, which revealed the increasing popularity of alternative DAPT regimens with the aforementioned devices. Thromboembolic or hemorrhagic complications associated with antiplatelet medications were similar across all medications. DAPT with ticagrelor, tirofiban, or prasugrel are effective and safe alternatives to clopidogrel and do not require enzymatic activation. Further clinical trials are needed to evaluate different antiplatelet regimens with various devices to establish highest-level evidence-based guidelines and recommendations.

Economic evaluation of pharmacogenomic-guided antiplatelet treatment in Spanish patients suffering from acute coronary syndrome participating in the U-PGx PREPARE study

BACKGROUND

Cardiovascular diseases and especially Acute Coronary Syndrome (ACS) constitute a major health issue impacting millions of patients worldwide. Being a leading cause of death and hospital admissions in many European countries including Spain, it accounts for enormous amounts of healthcare expenditures for its management. Clopidogrel is one of the oldest antiplatelet medications used as standard of care in ACS.

METHODS

In this study, we performed an economic evaluation study to estimate whether a genome-guided clopidogrel treatment is cost-effective compared to conventional one in a large cohort of 243 individuals of Spanish origin suffering from ACS and treated with clopidogrel. Data were derived from the U-PGx PREPARE clinical trial. Effectiveness was measured as survival of individuals while study data on safety and efficacy, as well as on resource utilization associated with each adverse drug reaction were used to measure costs to treat these adverse drug reactions. A generalized linear regression model was used to estimate cost differences for both study groups.

RESULTS

Based on our findings, PGx-guided treatment group is cost-effective. PGx-guided treatment demonstrated to have 50% less hospital admissions, reduced emergency visits and almost 13% less ADRs compared to the non-PGx approach with mean QALY 1.07 (95% CI, 1.04-1.10) versus 1.06 (95% CI, 1.03-1.09) for the control group, while life years for both groups were 1.24 (95% CI, 1.20-1.26) and 1.23 (95% CI, 1.19-1.26), respectively. The mean total cost of PGx-guided treatment was 50% less expensive than conventional therapy with clopidogrel [€883 (95% UI, €316-€1582), compared to €1,755 (95% UI, €765-€2949)].

CONCLUSION

These findings suggest that PGx-guided clopidogrel treatment represents a cost-effective option for patients suffering from ACS in the Spanish healthcare setting.

The Signaling Pathway of the ADP Receptor P2Y12 in the Immune System: Recent Discoveries and New Challenges

P2Y12 is a G-protein-coupled receptor that is activated upon ADP binding. Considering its well-established role in platelet activation, blocking P2Y12 has been used as a therapeutic strategy for antiplatelet aggregation in cardiovascular disease patients. However, receptor studies have shown that P2Y12 is functionally expressed not only in platelets and the microglia but also in other cells of the immune system, such as in monocytes, dendritic cells, and T lymphocytes. As a result, studies were carried out investigating whether therapies targeting P2Y12 could also ameliorate inflammatory conditions, such as sepsis, rheumatoid arthritis, neuroinflammation, cancer, COVID-19, atherosclerosis, and diabetes-associated inflammation in animal models and human subjects. This review reports what is known about the expression of P2Y12 in the cells of the immune system and the effect of P2Y12 activation and/or inhibition in inflammatory conditions. Lastly, we will discuss the major problems and challenges in studying this receptor and provide insights on how they can be overcome.

Pharmacogenetics of Antiplatelet Therapy

Antiplatelet therapy is used in the treatment of patients with acute coronary syndromes, stroke, and those undergoing percutaneous coronary intervention. Clopidogrel is the most widely used antiplatelet P2Y12 inhibitor in clinical practice. Genetic variation in CYP2C19 may influence its enzymatic activity, resulting in individuals who are carriers of loss-of-function CYP2C19 alleles and thus have reduced active clopidogrel metabolites, high on-treatment platelet reactivity, and increased ischemic risk. Prospective studies have examined the utility of CYP2C19 genetic testing to guide antiplatelet therapy, and more recently published meta-analyses suggest that pharmacogenetics represents a key treatment strategy to individualize antiplatelet therapy. Rapid genetic tests, including bedside genotyping platforms that are validated and have high reproducibility, are available to guide selection of P2Y12 inhibitors in clinical practice. The aim of this review is to provide an overview of the background and rationale for the role of a guided antiplatelet approach to enhance patient care.

Sex Differences in Clopidogrel Effects Among Young Patients With Acute Coronary Syndrome: A Role for Genetics?

Background

Poorer health outcomes experienced by young women with acute coronary syndrome may be related to sex differences in the safety and efficacy of antiplatelet agents, such as clopidogrel. Polymorphisms in drug metabolism enzyme (cytochrome P450 [CYP] family) genes are independent factors for the variability in response to clopidogrel. However, a sex-specific impact of genetics to explain worse clinical outcomes in women has not been explored extensively. Therefore, our objective was to determine whether an interaction of sex with CYP variants occurs among users of clopidogrel, and if so, its impact on 1-year adverse clinical outcomes.

Methods

We used data from a combined cohort of 2272 patients (median age 49 years; 56% female) hospitalized for acute coronary syndrome. We examined interactions between sex and CYP variants among clopidogrel users at admission and discharge to assess associations with 1-year readmission due to cardiac events.

Results

The case-only analysis of 177 participants on clopidogrel at the time of presentation showed that the risk of an atherothrombotic event was greater in female carriers of the CYP2C9∗3 loss-of-function allele (odds ratio = 3.77, 95% confidence interval = 1.54-9.24). The results of the multivariable logistic regression model for users of clopidogrel at discharge (n = 1733) indicated that women had significantly higher risk of atherothrombotic readmissions at 1 year (odds ratio = 1.55, 95% confidence interval = 1.16-2.07), compared to the risk for men, but the loss-of-function alleles, either individually or through a genetic risk score, were not associated with 1-year readmissions.

Conclusion

This study highlights the need for an improved understanding of the role of sex-by-gene interactions in causing sex differences in drug metabolism.

Ideal P2Y12 Inhibitor in Acute Coronary Syndrome: A Review and Current Status

Dual antiplatelet therapy (DAPT) has remained the cornerstone for management of acute coronary syndrome (ACS) over the years. Clopidogrel has been the quintessential P2Y12 receptor (platelet receptor for Adenosine 5′ diphosphate) inhibitor for the past two decades. With the demonstration of unequivocal superior efficacy of prasugrel/ticagrelor over clopidogrel, guidelines now recommend these agents in priority over clopidogrel in current management of ACS. Cangrelor has revived the interest in injectable antiplatelet therapy too. Albeit the increased efficacy of these newer agents comes at the cost of increased bleeding and this becomes more of a concern when combined with aspirin. Which P2Y12i is superior over another has been intensely debated over last few years after the ISAR-REACT 5 study with inconclusive data. Three novel antiplatelet agents are already in the pipeline for ACS with all of them succeeding in phase II studies. The search for an ideal antiplatelet remains a need of the hour for optimal reduction of ischemic events in ACS.

Prevention of Anthracycline-Induced Cardiotoxicity: The Good and Bad of Current and Alternative Therapies

Doxorubicin (Dox)-induced cardiotoxicity (DIC) remains a serious health burden, especially in developing countries. Unfortunately, the high cost of current preventative strategies has marginalized numerous cancer patients because of socio-economic factors. In addition, the efficacy of these strategies, without reducing the chemotherapeutic properties of Dox, is frequently questioned. These limitations have widened the gap and necessity for alternative medicines, like flavonoids, to be investigated. However, new therapeutics may also present their own shortcomings, ruling out the idea of “natural is safe”. The U.S. Food and Drug Administration (FDA) has stipulated that the concept of drug-safety be considered in all pre-clinical and clinical studies, to explore the pharmacokinetics and potential interactions of the drugs being investigated. As such our studies on flavonoids, as cardio-protectants against DIC, have been centered around cardiac and cancer models, to ensure that the efficacy of Dox is preserved. Our findings thus far suggest that flavonoids of Galenia africana could be suitable candidates for the prevention of DIC. However, this still requires further investigation, which would focus on drug-interactions as well as in vivo experimental models to determine the extent of cardioprotection.

Cytochrome P450 Enzymes and Drug Metabolism in Humans

Human cytochrome P450 (CYP) enzymes, as membrane-bound hemoproteins, play important roles in the detoxification of drugs, cellular metabolism, and homeostasis. In humans, almost 80% of oxidative metabolism and approximately 50% of the overall elimination of common clinical drugs can be attributed to one or more of the various CYPs, from the CYP families 1–3. In addition to the basic metabolic effects for elimination, CYPs are also capable of affecting drug responses by influencing drug action, safety, bioavailability, and drug resistance through metabolism, in both metabolic organs and local sites of action. Structures of CYPs have recently provided new insights into both understanding the mechanisms of drug metabolism and exploiting CYPs as drug targets. Genetic polymorphisms and epigenetic changes in CYP genes and environmental factors may be responsible for interethnic and interindividual variations in the therapeutic efficacy of drugs. In this review, we summarize and highlight the structural knowledge about CYPs and the major CYPs in drug metabolism. Additionally, genetic and epigenetic factors, as well as several intrinsic and extrinsic factors that contribute to interindividual variation in drug response are also reviewed, to reveal the multifarious and important roles of CYP-mediated metabolism and elimination in drug therapy.

Clinical importance of testing for clopidogrel resistance in patients undergoing carotid artery stenting-a systematic review

Dual antiplatelet therapy is frequently prescribed for patients undergoing carotid artery stenting (CAS), however clopidogrel resistance might cause thromboembolic complications. The role of testing for clopidogrel resistance in patients undergoing CAS is unclear. In this study, we aimed to review the periprocedural thromboembolic outcomes in clopidogrel resistant patients who underwent CAS. We conducted a review of PubMed, EMBASE, and the Cochrane Library up to October 7, 2020. Studies were included that investigated at least ten patients aged 18 years or older with a symptomatic carotid artery stenosis requiring CAS. Studies were excluded that investigated patients with a carotid artery dissection, case reports, case series of less than ten patients, reviews, commentaries, letters to the editors, and conference abstracts. The primary endpoint was the incidence of thromboembolic events. One hundred seventy-seven unique articles were identified of which three studies were included in our systematic review. The sample sizes ranged from 76 to 449 patients and the follow-up duration from 24 hours to 2 years postprocedural. Two retrospective observational studies determined clopidogrel resistance using measurement of P2Y12 reaction units, and one historical cohort study used genetic testing. Two studies concluded that clopidogrel resistance was a risk factor for thromboembolic complications, the other found higher values of P2Y12 reaction units in patients with thromboembolic events compared to those without. In conclusion, current literature supports a possible relationship between clopidogrel resistance and thromboembolic complications in patients who underwent CAS. Preprocedural testing for clopidogrel resistance might therefore be of additional value. Randomized studies using a valid, reliable clopidogrel resistance test and clinical endpoints, are however required to make a definitive statement and to determine the impact of the thromboembolic complications. This study was registered within PROSPERO (CRD42020197318).

Prevalence of CYP2C19 and ITGB3 polymorphisms among Bangladeshi patients who underwent percutaneous coronary intervention

INTRODUCTION

Antithrombotic agents are the basic therapeutic option for patients with arterial thrombosis who underwent percutaneous coronary intervention (PCI). In Bangladesh, aspirin and clopidogrel are frequently prescribed as antithrombotics or platelet inhibitors. Studies reported the genetic polymorphisms of CYP2C19*2, CYP2C19*17, and ITGB3 cause an alteration of the pharmacodynamic and pharmacokinetic profile of aspirin and clopidogrel. Therefore, we aimed to assess the prevalence of CYP2C19*2, CYP2C19*17, and ITGB3 polymorphisms among Bangladeshi patients with cardiovascular disease (CVD) who underwent PCI.

METHODS

Here we assessed a total of 1,000 CVD patients (male 782 and female 218) who underwent PCI and were treated with clopidogrel and/or aspirin. We performed genotyping of patients treated with clopidogrel and aspirin by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and tetra-primer amplification refractory mutation system PCR (T-ARMS-PCR) methods. The PCR products of clopidogrel-treated patients were screened with agarose gel electrophoresis and then digested with SmaI and NsiI-HF for CYP2C19*2 and CYP2C19*17, respectively. We genotyped aspirin-treated patients with T-ARMS-PCR for missense rs5918 (PlA1/A1) polymorphism of the ITGB3 gene. Then we ran the digested PCR products on 2% agarose gel electrophoresis to detect the mentioned polymorphisms.

RESULTS

Among the clopidogrel-treated patients, we observed 64.1% polymorphism (hetero + mutant) of CYP2C19*2 (loss-of-function allele) and 22.7% (hetero + mutant) of CYP2C19*17 (gain-of-function allele). On the other hand, among the aspirin-treated patients, polymorphisms of ITGB3 were 84.1% homozygous (PlA1/A1), 15.6% heterozygous (PlA1/A2), and 0.3% mutant homozygous.

CONCLUSION

In the present study, we observed a high prevalence of genetic polymorphisms of CYP2C19 and ITGB3 genes. Therefore, we recommend genotyping of CVD patients before prescribing clopidogrel or aspirin to prevent coagulation. Based on the genotyping study, the adjustment of doses or alternative generics might require to avoid therapeutic failure or toxicity in some cases.

A Clinical Update on Antiplatelet Therapy in Secondary Prevention of Ischemic Stroke

PURPOSE OF REVIEW

Antiplatelet therapy remains the standard of care in secondary stroke prevention for non-cardioembolic ischemic stroke and transient ischemic attack. We aim to examine the use of antiplatelet agents in secondary prevention through highlighting relevant clinical trials and meta-analyses as well as providing commentary regarding our practice.

RECENT FINDINGS

In the POINT and CHANCE trials, dual antiplatelet therapy reduced recurrent stroke compared to aspirin monotherapy. Sub-analyses of these trials suggest that genetic polymorphisms could play a role in diminishing the effectiveness of clopidogrel. Similarly, THALES demonstrated better outcomes with ticagrelor-aspirin combination therapy over aspirin monotherapy. Combination antiplatelet therapy with aspirin and the P2Y12 inhibitors, clopidogrel and ticagrelor, reduced stroke recurrence in those presenting with mild ischemic stroke or high risk TIA. Genetic polymorphisms may play a role in determining the appropriate regimen. Questions remain regarding the optimal duration of combination antiplatelet therapy for various stroke etiologies.

Risk of stroke in CYP2C19 LoF polymorphism carrier coronary artery disease patients undergoing clopidogrel therapy: An ethnicity-based updated meta-analysis

BACKGROUND

Antiplatelet agent clopidogrel has been widely used for stroke management for many years, although resistance to clopidogrel may increase the chance of stroke recurrence. CYP2C19 loss-of-function (LoF) polymorphism is assumed to be responsible for the poor metabolism of clopidogrel that ultimately turns to resistance. Previous publications could not provide firm evidence due to highly conflicting and heterogeneous outcomes.

AIM

To get clear evidence from an updated meta-analysis on CYP2C19 LoF polymorphism association with stroke risk in clopidogrel treated patients, this study has been performed.

METHODS

We conducted a meta-analysis with 72 selected studies from authentic databases, including 40,035 coronary artery disease patients treated with clopidogrel.

RESULTS

This analysis showed that the worldwide carrier of one or more CYP2C19 LoF alleles had a significantly higher risk of stroke and composite events than the non-LoF carriers (RR=1.78, 95% CI=1.52-2.07, p<0.00001 and RR=1.39, 95% CI=1.26-1.54, p<0.00001, respectively). Besides, subgroup analysis showed that Asian CYP2C19 LoF carriers had a significantly increased risk of stroke (RR=1.91, 95% CI=1.60-2.28, p<0.00001) while the risk of composite events was significantly higher in all ethnic populations (Asian: RR=1.58, 95% CI=1.32-1.89, p<0.00001; Caucasian: RR=1.27, 95% CI=1.08-1.50, p=0.003; Hispanic and others: RR=1.21, 95% CI=1.09-1.34, p=0.0003).

CONCLUSION

Our meta-analysis confirmed that the presence of CYP2C19 LoF alleles increases the risk of stroke and composite events recurrence in the worldwide population, especially in Asians undergoing clopidogrel treatment. Alternative antiplatelet therapy should be investigated thoroughly for the intermediate and poor metabolizers.

An Analysis of Pharmacogenomic-Guided Pathways and Their Effect on Medication Changes and Hospital Admissions: A Systematic Review and Meta-Analysis

Ninety-five percent of the population are estimated to carry at least one genetic variant that is discordant with at least one medication. Pharmacogenomic (PGx) testing has the potential to identify patients with genetic variants that puts them at risk of adverse drug reactions and sub-optimal therapy. Predicting a patient's response to medications could support the safe management of medications and reduce hospitalization. These benefits can only be realized if prescribing clinicians make the medication changes prompted by PGx test results. This review examines the current evidence on the impact PGx testing has on hospital admissions and whether it prompts medication changes. A systematic search was performed in three databases (Medline, CINAHL and EMBASE) to search all the relevant studies published up to the year 2020, comparing hospitalization rates and medication changes amongst PGx tested patients with patients receiving treatment-as-usual (TAU). Data extracted from full texts were narratively synthesized using a process model developed from the included studies, to derive themes associated to a suggested workflow for PGx-guided care and its expected benefit for medications optimization and hospitalization. A meta-analysis was undertaken on all the studies that report the number of PGx tested patients that had medication change(s) and the number of PGx tested patients that were hospitalized, compared to participants that received TAU. The search strategy identified 5 hospitalization themed studies and 5 medication change themed studies for analysis. The meta-analysis showed that medication changes occurred significantly more frequently in the PGx tested arm across 4 of 5 studies. Meta-analysis showed that all-cause hospitalization occurred significantly less frequently in the PGx tested arm than the TAU. The results show proof of concept for the use of PGx in prescribing that produces patient benefit. However, the review also highlights the opportunities and evidence gaps that are important when considering the introduction of PGx into health systems; namely patient involvement in PGx prescribing decisions, thus a better understanding of the perspective of patients and prescribers. We highlight the opportunities and evidence gaps that are important when considering the introduction of PGx into health systems.

Human Variability in Carboxylesterases and carboxylesterase-related Uncertainty Factors for Chemical Risk Assessment

Carboxylesterases (CES) are an important class of enzymes involved in the hydrolysis of a range of chemicals and show large inter-individual variability in vitro. An extensive literature search was performed to identify in vivo probe substrates for CES1 and CES2 together with their protein content and enzymatic activity. Human pharmacokinetic (PK) data on Cmax, clearance, and AUC were extracted from 89 publications and Bayesian meta-analysis was performed using a hierarchical model to derive CES-related variability distributions and related uncertainty factors (UF). The CES-related variability indicated that 97.5% of healthy adults are covered by the kinetic default UF (3.16), except for clopidogrel and dabigatran etexilate. Clopidogrel is metabolised for a small amount by the polymorphic CYP2C19, which can have an impact on the overall pharmacokinetics, while the variability seen for dabigatran etexilate might be due to differences in the absorption, since this can be influenced by food intake. The overall CES-related variability was moderate to high in vivo (<CV 50%), which might be due to possible polymorphism in the enzyme but also to the small sample size available per chemical. The presented CES-related variability can be used in combination with in vitro data to derive pathway-specific distributions.

Interactions between cardiology and oncology drugs in precision cardio-oncology

Recent advances in treatment have transformed the management of cancer. Despite these advances, cardiovascular disease remains a leading cause of death in cancer survivors. Cardio-oncology has recently evolved as a subspecialty to prevent, diagnose, and manage cardiovascular side effects of antineoplastic therapy. An emphasis on optimal management of comorbidities and close attention to drug interactions are important in cardio-oncologic care. With interdisciplinary collaboration among oncologists, cardiologists, and pharmacists, there is potential to prevent and reduce drug-related toxicities of treatments. The cytochrome P450 (CYP450) family of enzymes and the P-glycoprotein (P-g) transporter play a crucial role in drug metabolism and drug resistance. Here we discuss the role of CYP450 and P-g in drug interactions in the field of cardio-oncology, provide an overview of the cardiotoxicity of a spectrum of cancer agents, highlight the role of precision medicine, and encourage a multidisciplinary treatment approach for patients with cancer.

Pharmacogenomics in the United States Community Pharmacy Setting: The Clopidogrel-CYP2C19 Example

Pharmacogenomics (PGx) is expanding across health-care practice settings, including the community pharmacy. In the United States, models of implementation of PGx in the community pharmacy have described independent services and those layered on to medication therapy management. The drug-gene pair of clopidogrel-CYP2C19 has been a focus of implementation of PGx in community pharmacy and serves as an example of the evolution of the application of drug-gene interaction information to help optimize drug therapy. Expanded information related to this drug-gene pair has been provided by the US Food and Drug Administration and clinical PGx guidelines have and continue to be updated to support clinical decision-making. Most recently direct-to-consumer (DTC) PGx has resulted in patient generated sample collection and submission to a genetic testing-related company for analysis, with reporting of genotype and related phenotype information directly to the patient without a health-care professional guiding or even being involved in the process. The DTC testing approach needs to be considered in the development or modification of PGx service models in the community pharmacy setting. The example of clopidogrel-CYP2C19 is discussed and current models of PGx implementation in the community pharmacy in the United States are presented. New approaches to PGx services are offered as implementation continues to evolve and may now include DTC information.

Flavonoids as potential anti-platelet aggregation agents: from biochemistry to health promoting abilities

Cardiovascular ailments are the number one cause of mortalities throughout the globe with 17.9 million deaths per year. Platelet activation and aggregation play a crucial role in the pathogenesis of arterial diseases, including acute coronary syndrome, acute myocardial infarction, cerebrovascular transient ischemia, unstable angina, among others. Flavonoids-rich plant extracts are gaining interest for treating the heart-related problems due to safe nature of these herbal extracts. Consumption of plant-food-derived bioactives, particularly flavonoids, has shown antithrombotic, and cardiovascular protective effects due to its anti-platelet activity. Preclinical and clinical trials have proven that flavonoid-rich plant extracts are protective against the cardiac ailments through anti-platelet aggregation activity. This review aims to highlight the anti-platelet aggregation potential of flavonoids with a key emphasis on the therapeutic efficacy in humans. The mechanism of flavonoids in preventing and treating cardiovascular diseases is also highlighted based on preclinical and clinical experimental trials. Further studies are the need of time for exploring the exact molecular mechanism of flavonoids as anti-platelet aggregation agents for treating heart-related problems.

A Pharmacogenetic Study of CYP2C19 in Acute Coronary Syndrome Patients of Colombian Origin Reveals New Polymorphisms Potentially Related to Clopidogrel Therapy

Clopidogrel, an oral platelet P2Y₁₂ receptor blocker, is used in the treatment of acute coronary syndrome. Interindividual variability in treatment response and the occurrence of adverse effects has been attributed to genetic variants in CYP2C19. The analysis of relevant pharmacogenes in ethnically heterogeneous and poorly studied populations contributes to the implementation of personalized medicine. We analyzed the coding and regulatory regions of CYP2C19 in 166 patients with acute coronary syndrome (ACS) treated with clopidogrel. The allele frequencies of CYP2C19 alleles *1, *2, *4, *17, *27 and *33 alleles were 86.1%, 7.2%, 0.3%, 10.2%, 0.3% and 0.3%, respectively. A new potentially pathogenic mutation (p.L15H) and five intronic variants with potential splicing effects were detected. In 14.4% of the patients, a new haplotype in strong linkage disequilibrium was identified. The clinical outcome indicated that 13.5% of the patients presented adverse drugs reactions with a predominance of bleeding while 25% of these patients were carriers of at least one polymorphic allele. We propose that new regulatory single-nucleotide variants (SNVs) might potentially influence the response to clopidogrel in Colombian individuals.

The Role of Genetic Polymorphism and Other Factors on Clopidogrel Resistance (CR) in an Asian Population with Coronary Heart Disease (CHD)

Clopidogrel is a widely-used antiplatelet drug. It is important for the treatment and prevention of coronary heart disease. Clopidogrel can effectively reduce platelet activity and therefore reduce stent thrombosis. However, some patients still have ischemic events despite taking the clopidogrel due to the alteration in clopidogrel metabolism attributable to various genetic and non-genetic factors. This review aims to summarise the mechanisms and causes of clopidogrel resistance (CR) and potential strategies to overcome it. This review summarised the possible effects of genetic polymorphism on CR among the Asian population, especially CYP2C19 *2 / *3 / *17, where the prevalence rate among Asians was 23.00%, 4.61%, 15.18%, respectively. The review also studied the effects of other factors and appropriate strategies used to overcome CR. Generally, CR among the Asian population was estimated at 17.2-81.6%. Therefore, our overview provides valuable insight into the causes of RC. In conclusion, understanding the prevalence of drug metabolism-related genetic polymorphism, especially CYP2C19 alleles, will enhance clinical understanding of racial differences in drug reactions, contributing to the development of personalised medicine in Asia.

Bleeding associated with co-administration of clopidogrel and ACEi in patients undergoing PCI and DAPT

BACKGROUND AND AIMS

The coprescription of an angiotensin-converting enzyme inhibitor (ACEi) with clopidogrel reportedly increases bleeding risk. However, studies have not described such an increase in cases of dual antiplatelet therapy (DAPT) after percutaneous coronary intervention (PCI).

METHODS

We analyzed electronic medical records of patients with discharge records of having undergone DAPT after PCI from a national health insurance claims database for January 1, 2006 to December 31, 2014. The date of PCI was the index date, and the primary outcome was major bleeding. The unit of analysis was one person-quarter. We compared patients who were prescribed with those not prescribed an ACEi in the cohort. A Poisson model with inverse probability of treatment weighting was fitted using generalized estimating equations to measure the risk of outcomes.

RESULTS

In total, 193,258 patients underwent DAPT after PCI; 46% had a coprescription of an ACEi. After screening, 170,775 patients (479,263 person-quarters) remained for analysis. The mean patient age was 65 ± 13 years, and 73.43% were men. In total, 79,739 prescriptions of an ACEi were written: 57%, 14.21%, 8.88%, 7.17%, and 4.68% were for captopril, ramipril, enalapril, perindopril, and imidapril, respectively. A concomitant prescription of an ACEi with clopidogrel was not associated with increased bleeding risk (adjusted rate ratio: 1.08, 99% confidence interval: 0.99-1.17).

CONCLUSIONS

The coadministration of an ACEi with clopidogrel after PCI is common. In this real-world cohort study, such coadministration was not associated with an increased risk of major bleeding in patients undergoing DAPT after PCI.

Short- and long-term cost-effectiveness analysis of CYP2C19 genotype-guided therapy, universal clopidogrel, versus universal ticagrelor in post-percutaneous coronary intervention patients in Qatar

BACKGROUND

Patients having CYP2C19 loss-of-function alleles and receiving clopidogrel are at higher risk of adverse cardiovascular outcomes. Ticagrelor is an effective antiplatelet that is unaffected by the CYP2C19 polymorphism. The main aim of the current research is to evaluate the cost-effectiveness among CYP2C19 genotype-guided therapy, universal ticagrelor, and universal clopidogrel after a percutaneous coronary intervention (PCI).

METHODS

A two-part decision-analytic model, including a one-year model and a 20-year follow-up Markov model, was created to follow the use of (i) universal clopidogrel, (ii) universal ticagrelor, and (iii) genotype-guided antiplatelet therapy. Outcome measures were the incremental cost-effectiveness ratio (ICER, cost/success) and incremental cost-utility ratio (ICUR, cost/quality-adjusted life years [QALY]). Therapy success was defined as survival without myocardial infarction, stroke, cardiovascular death, stent thrombosis, and no therapy discontinuation because of adverse events, i.e. major bleeding and dyspnea. The model was based on a multivariate analysis, and a sensitivity analysis confirmed the robustness of the model outcomes, including against variations in drug acquisition costs.

RESULTS

Against universal clopidogrel, genotype-guided therapy was cost-effective over the one-year duration (ICER, USD 6102 /success), and dominant over the long-term. Genotype-guided therapy was dominant against universal ticagrelor over the one-year duration, and cost-effective over the long term (ICUR, USD 1383 /QALY). Universal clopidogrel was dominant over ticagrelor for the short term, and cost-effective over the long-term (ICUR, USD 10,616 /QALY).

CONCLUSION

CYP2C19 genotype-guided therapy appears to be the preferred antiplatelet strategy, followed by universal clopidogrel, and then universal ticagrelor for post-PCI patients in Qatar.

Analysis of the Potential Association of Drug-Metabolizing Enzymes CYP2C9*3 and CYP2C19*3 Gene Variations With Type 2 Diabetes: A Case-Control Study

BACKGROUND

Cytochrome P450s (CYPs) are drug-metabolizing enzymes catalyzing the metabolism of about 75% of drug in clinical use. CYP2C9 represents 20% CYP proteins in liver cells and is a crucial member of CYPs superfamily. CYP2C19 metabolizes very important drugs such as antiulcer drug omeprazole, the antiplatelet drug clopidogrel and anticonvulsant mephenytoin. Single nucleotide polymorphisms (SNPs) of CYP genes have been associated with unexpected drug reactions and diseases in different populations.

OBJECTIVE

We examined the associations of CYP2C9*3 (rs1057910) and CYP2C19*3 (rs4986893) with T2D in Saudi population.

METHODS

We used the allele-specific PCR (AS-PCR) and DNA sequencing in 111 cases and 104 controls for rs1057910, and in 119 cases and 110 controls for rs4986893.

RESULTS

It is indicated that the genotype distribution of rs1057910 in cases and controls were not significantly different (P=0.0001). The genotypes of rs1057910 were not associated with type 2 diabetes (T2D) (P>0.05). Whereas the genotype distribution of rs4986893 in cases and controls was significantly different (P=0.049). The AA genotype of rs4986893 may be associated in increased risk to T2D with OR=17.25 (2.06-143.8), RR=6.14(0.96-39.20), P=0.008.

CONCLUSION

The CYP2C9*3 (rs1057910) may not be associated with T2D, while CYP2C19*3 (rs4986893) is probably associated with T2D. These findings need to be validated in follow-up studies with larger sample sizes and different populations.

Impact of selected genetic factors on clopidogrel inactive metabolite level and antiplatelet response in patients after percutaneous coronary intervention

Background and objective

Clopidogrel is frequently used as part of optimal dual antiplatelet therapy in high-bleeding risk patients with the acute coronary syndrome. The concentration of the inactive carboxylic acid metabolite of clopidogrel might be useful to evaluate the response to clopidogrel therapy. Therefore, we sought to correlate the inhibition of platelet aggregation with the plasma level of the inactive metabolite of clopidogrel in patients after percutaneous coronary interventions (PCI) and their associations with the most frequently studied genetic polymorphisms. For this purpose, the fast and simple HPLC method for determining the concentration of the inactive metabolite was developed.

Methods

The effect of CYP2C19, CYP3A4/5, ABCB1 and PON1 genes on the plasma inactive metabolite concentration of clopidogrel and the platelet aggregation was investigated in 155 patients before and after PCI.

Results

The concentration of the inactive metabolite of clopidogrel was not significantly different in the intermediate metabolizers (IM) of CYP2C19 compared with extensive metabolizers (EM) both before and after PCI, while inhibition of platelet aggregation was found to be significantly better in EM than in IM. The presence of the A allele at position 2677 in the ABCB1 gene was associated with a significantly lower concentration of inactive metabolite of clopidogrel before PCI.

Conclusion

The CYP2C19*2 allele was associated with decreased platelet reactivity during clopidogrel therapy before and after PCI. Simultaneous determination of platelet aggregation and concentration of the inactive clopidogrel metabolite may be useful in clinical practice to find the cause of adverse effects or insufficient treatment effect in patients chronically treated with clopidogrel.

Inter-phenotypic differences in CYP2C9 and CYP2C19 metabolism: Bayesian meta-regression of human population variability in kinetics and application in chemical risk assessment

Quantifying variability in pharmacokinetics (PK) and toxicokinetics (TK) provides a science-based approach to refine uncertainty factors (UFs) for chemical risk assessment. In this context, genetic polymorphisms in cytochromes P450 (CYPs) drive inter-phenotypic differences and may result in reduction or increase in metabolism of drugs or other xenobiotics. Here, an extensive literature search was performed to identify PK data for probe substrates of the human polymorphic isoforms CYP2C9 and CYP2C19. Relevant data from 158 publications were extracted for markers of chronic exposure (clearance and area under the plasma concentration-time curve) and analysed using a Bayesian meta-regression model. Enzyme function (EF), driven by inter-phenotypic differences across a range of allozymes present in extensive and poor metabolisers (EMs and PMs), and fraction metabolised (Fm), were identified as exhibiting the highest impact on the metabolism. The Bayesian meta-regression model provided good predictions for such inter-phenotypic differences. Integration of population distributions for inter-phenotypic differences and estimates for EF and Fm allowed the derivation of CYP2C9- and CYP2C19-related UFs which ranged from 2.7 to 12.7, and were above the default factor for human variability in TK (3.16) for PMs and major substrates (Fm >60%). These results provide population distributions and pathway-related UFs as conservative in silico options to integrate variability in CYP2C9 and CYP2C19 metabolism using in vitro kinetic evidence and in the absence of human data. The future development of quantitative extrapolation models is discussed with particular attention to integrating human in vitro and in vivo PK or TK data with pathway-related variability for chemical risk assessment.

Whole-Genome Sequencing Identifies Novel Functional Loci Associated with Lung Function in Puerto Rican Youth

Rationale: Puerto Ricans have the highest childhood asthma prevalence in the United States (23.6%); however, the etiology is uncertain.Objectives: In this study, we sought to uncover the genetic architecture of lung function in Puerto Rican youth with and without asthma who were recruited from the island (n = 836).Methods: We used admixture-mapping and whole-genome sequencing data to discover genomic regions associated with lung function. Functional roles of the prioritized candidate SNPs were examined with chromatin immunoprecipitation sequencing, RNA sequencing, and expression quantitative trait loci data.Measurements and Main Results: We discovered a genomic region at 1q32 that was significantly associated with a 0.12-L decrease in the lung volume of exhaled air (95% confidence interval, -0.17 to -0.07; P = 6.62 × 10^-8) with each allele of African ancestry. Within this region, two SNPs were expression quantitative trait loci of TMEM9 in nasal airway epithelial cells and MROH3P in esophagus mucosa. The minor alleles of these SNPs were associated with significantly decreased lung function and decreased TMEM9 gene expression. Another admixture-mapping peak was observed on chromosome 5q35.1, indicating that each Native American ancestry allele was associated with a 0.15-L increase in lung function (95% confidence interval, 0.08-0.21; P = 5.03 × 10^-6). The region-based association tests identified four suggestive windows that harbored candidate rare variants associated with lung function.Conclusions: We identified common and rare genetic variants that may play a critical role in lung function among Puerto Rican youth. We independently validated an inflammatory pathway that could potentially be used to develop more targeted treatments and interventions for patients with asthma.

Human Cell Modeling for Cardiovascular Diseases

The availability of appropriate and reliable in vitro cell models recapitulating human cardiovascular diseases has been the aim of numerous researchers, in order to retrace pathologic phenotypes, elucidate molecular mechanisms, and discover therapies using simple and reproducible techniques. In the past years, several human cell types have been utilized for these goals, including heterologous systems, cardiovascular and non-cardiovascular primary cells, and embryonic stem cells. The introduction of induced pluripotent stem cells and their differentiation potential brought new prospects for large-scale cardiovascular experiments, bypassing ethical concerns of embryonic stem cells and providing an advanced tool for disease modeling, diagnosis, and therapy. Each model has its advantages and disadvantages in terms of accessibility, maintenance, throughput, physiological relevance, recapitulation of the disease. A higher level of complexity in diseases modeling has been achieved with multicellular co-cultures. Furthermore, the important progresses reached by bioengineering during the last years, together with the opportunities given by pluripotent stem cells, have allowed the generation of increasingly advanced in vitro three-dimensional tissue-like constructs mimicking in vivo physiology. This review provides an overview of the main cell models used in cardiovascular research, highlighting the pros and cons of each, and describing examples of practical applications in disease modeling.

Major CYP450 polymorphism Among Saudi Patients

BACKGROUND

Cytochrome P450 (CYP) contributes to a huge collection of medicinal products' Phase I metabolization. We aimed to summarize and investigate the current evidence regarding the frequency of CYP2D6, CYP2C9, CYP2C19, MDR1 in Saudi Arabia.

METHODS

A computerized search in four databases was done using the relevant keywords. Screening process was done in two steps; title and abstract screening and full-text screening. Data of demographic and characteristics of included studies and patients was extracted and tabulated.

RESULTS

Ten studies were eligible for our criteria and were included in this systematic review. Age of participants ranged between 17-65 years. Only two subjects showed PM phenotype of CYP2C19 in Saudi population. The most frequent alleles were CYP2C19*1 (62.9%), CYP2C19*2 (11.2%-32%), and CYP2C19*17 (25.7%). The CYP2C19m1 was observed in 97 cases of extensive metabolizing (EM) phenotype CYP2C19. Concerning the CYP2C9, the most frequent alleles were CYP2C9*1 and CYP2C9*2, and the most frequent genotype was CYP2C9*1*1. The CYP2D6*41 allele and C1236T MDR1 were the most frequent allele in this population.

CONCLUSION

The current evidence suggests that Saudi Arabians resembled European in the frequency of CYP2C19, Caucasians in both the incidence of CYP2C9 and CYP2C19m1 and absence of CYP2C19m2. The CYP2D6*41 allele frequency in Saudi Arabians is relatively high. We recommend a further research to evaluate the basic and clinical relevance of gene polymorphism in such ethnicity.

Next-Generation Sequencing of CYP2C19 in Stent Thrombosis: Implications for Clopidogrel Pharmacogenomics

PURPOSE

Describe CYP2C19 sequencing results in the largest series of clopidogrel-treated cases with stent thrombosis (ST), the closest clinical phenotype to clopidogrel resistance. Evaluate the impact of CYP2C19 genetic variation detected by next-generation sequencing (NGS) with comprehensive annotation and functional studies.

METHODS

Seventy ST cases on clopidogrel identified from the PLATO trial (n = 58) and Mayo Clinic biorepository (n = 12) were matched 1:1 with controls for age, race, sex, diabetes mellitus, presentation, and stent type. NGS was performed to cover the entire CYP2C19 gene. Assessment of exonic variants involved measuring in vitro protein expression levels. Intronic variants were evaluated for potential splicing motif variations.

RESULTS

Poor metabolizers (n = 4) and rare CYP2C19*8, CYP2C19*15, and CYP2C19*11 alleles were identified only in ST cases. CYP2C19*17 heterozygote carriers were observed more frequently in cases (n = 29) than controls (n = 18). Functional studies of CYP2C19 exonic variants (n = 11) revealed 3 cases and only 1 control carrying a deleterious variant as determined by in vitro protein expression studies. Greater intronic variation unique to ST cases (n = 169) compared with controls (n = 84) was observed with predictions revealing 13 allele candidates that may lead to a potential disruption of splicing and a loss-of-function effect of CYP2C19 in ST cases.

CONCLUSION

NGS detected CYP2C19 poor metabolizers and paradoxically greater number of so-called rapid metabolizers in ST cases. Rare deleterious exonic variation occurs in 4%, and potentially disruptive intronic alleles occur in 16% of ST cases. Additional studies are required to evaluate the role of these variants in platelet aggregation and clopidogrel metabolism.

Clopidogrel Pharmacogenetics

Common genetic variation in CYP2C19 (cytochrome P450, family 2, subfamily C, polypeptide 19) *2 and *3 alleles leads to a loss of functional protein, and carriers of these loss-of-function alleles when treated with clopidogrel have significantly reduced clopidogrel active metabolite levels and high on-treatment platelet reactivity resulting in increased risk of major adverse cardiovascular events, especially after percutaneous coronary intervention. The Food and Drug Administration has issued a black box warning advising practitioners to consider alternative treatment in CYP2C19 poor metabolizers who might receive clopidogrel and to identify such patients by genotyping. However, routine clinical use of genotyping for CYP2C19 loss-of-function alleles in patients undergoing percutaneous coronary intervention is not recommended by clinical guidelines because of lack of prospective evidence. To address this critical gap, TAILOR-PCI (Tailored Antiplatelet Initiation to Lessen Outcomes due to Decreased Clopidogrel Response After Percutaneous Coronary Intervention) is a large, pragmatic, randomized trial comparing point-of-care genotype-guided antiplatelet therapy with routine care to determine whether identifying CYP2C19 loss-of-function allele patients prospectively and prescribing alternative antiplatelet therapy is beneficial.

Influence of metabolic profiles on the safety of drug therapy in routine care in Germany: protocol of the cohort study EMPAR

INTRODUCTION

Pre-emptive testing of pharmacogenetically relevant single-nucleotide polymorphisms can be an effective tool in the prevention of adverse drug reactions and therapy resistance. However, most of the tests are not used as standard in routine care in Germany because of lacking evidence for the clinical and economical benefit and their impact on the usage of healthcare services. We address this issue by investigating the influence of pharmacogenetic profiles on the use of healthcare services over an extended period of several years using routine care data from a statutory health insurance company. The goal is to provide clinical evidence whether pre-emptive pharmacogenetic testing of metabolic profiles in routine care in Germany is beneficial and cost-effective.

METHODS AND ANALYSIS

The EMPAR (Einfluss metabolischer Profile auf die Arzneimitteltherapiesicherheit in der Routineversorgung) study is a non-interventional cohort study conducted to analyse pharmacogenetic risk factors that are important for drug therapy by means of endpoints relevant for healthcare. The analysis is based on pharmacogenetic profiles and statutory health insurance data. We perform pharmacogenetic, pharmacoepidemiological and pharmacoeconomic analyses using health care utilisation scores and machine learning techniques. Therefore, we aim to include about 10 000 patients (≥18 years) insured by the health insurance provider Techniker Krankenkasse. The study focuses on patients with prescriptions of anticoagulants and prescriptions of cholesterol-lowering drugs. Also, a screening for special pharmacogenetic characteristics will be performed in patients with at least one Y57.9! diagnosis (Complication of medical and surgical care: drug or medicament, unspecified). Outcomes include the utilisation of health insurance services, the incidence of incapacity for work and costs for drugs and treatment.

ETHICS AND DISSEMINATION

The protocol was approved by the Ethics Committee of the Medical Faculty, University of Bonn (Lfd. Nr. 339/17). The results of this research project will be published in scientific open access journals and at conferences.

TRIAL REGISTRATION NUMBER

German Clinical Trials Register, DRKS00013909.

The Role of CYP450 Drug Metabolism in Precision Cardio-Oncology

As many novel cancer therapies continue to emerge, the field of Cardio-Oncology (or onco-cardiology) has become crucial to prevent, monitor and treat cancer therapy-related cardiovascular toxicity. Furthermore, given the narrow therapeutic window of most cancer therapies, drug-drug interactions are prevalent in the cancer population. Consequently, there is an increased risk of affecting drug efficacy or predisposing individual patients to adverse side effects. Here we review the role of cytochrome P450 (CYP450) enzymes in the field of Cardio-Oncology. We highlight the importance of cardiac medications in preventive Cardio-Oncology for high-risk patients or in the management of cardiotoxicities during or following cancer treatment. Common interactions between Oncology and Cardiology drugs are catalogued, emphasizing the impact of differential metabolism of each substrate drug on unpredictable drug bioavailability and consequent inter-individual variability in treatment response or development of cardiovascular toxicity. This inter-individual variability in bioavailability and subsequent response can be further enhanced by genomic variants in CYP450, or by modifications of CYP450 gene, RNA or protein expression or function in various 'omics' related to precision medicine. Thus, we advocate for an individualized approach to each patient by a multidisciplinary team with clinical pharmacists evaluating a treatment plan tailored to a practice of precision Cardio-Oncology. This review may increase awareness of these key concepts in the rapidly evolving field of Cardio-Oncology.

New paradigm for expediting drug development in Asia

Some Asian regulators currently require Phase I data in Asians before joining global Phase II/III trials. Here, we discuss inherent limitations of Phase I ethnic sensitivity studies (ESS) to identify potential interethnic differences. We review recent new drug applications (NDAs) for Japan and China to critically assess the value of separate ESSs in Asian populations. Given that the observed value of ESS was limited, we propose a new global drug development paradigm: if relevant safety, pharmacokinetic (PK), and pharmacogenetic (PG) data are available from the original Phase I study population, it might be possible to extrapolate those data to Asian populations for their inclusion in Phase II/III trials, without an ESS. This could help to streamline drug development in Asia while still addressing regulatory requirements.

The Impact of Kinase Insert Domain (KDR) Gene Polymorphism rs2305948 on Clopidogrel Resistance in Iraqi Patients Undergoing Elective Percutaneous Coronary Intervention (PCI)

Introduction:

Clopidogrel, the first-choice antiplatelet agent for patient undergoing Percutaneous Coronary Intervention (PCI) along with Aspirin. Clopidogrel resistance is one of the major obstacles that cause MACE and failure of PCI. Kinase Insert Domain (KDR) gene responsible for VEGFR2 coding, the major receptor that translates VEGF ligand. The rs2305948 SNP in VEGFR2 gene has been documented to be involved atherogenesis and in CAD pathogenesis.

Aim:

To study the impact of KDR gene polymorphism rs2305948 on clopidogrel resistance in patients undergoing elective PCI.

Methods:

A case control study with 324 patients documented for elective PCI whom divided according to platelet aggregation level measured into (CR) with 111patients and (NCR) that consists of 213 patients. Serum lipids and VEGFR2 levels, BMI and platelet count were measured. Genotype for rs2305948 was done by PCR-RFLP.

Results:

Allele frequency and genotype results indicate a significant association with the pathogenesis of CR in all models in CR group compared to NCR group, a significant correlation for T allele with LDL, cholesterol and serum VEGFR2 in dominant and co-dominant models. RFLP-PCR results were documented by gene sequencing and results were compatible with HWE.

Conclusion:

rs2305948 SNP is associated with occurrences of CR and have an influence in the development of other metabolic changes.

Personalized antiplatelet therapy guided by a novel detection of platelet aggregation function in stable coronary artery disease patients undergoing percutaneous coronary intervention: a randomized controlled clinical trial

Aims

A number of studies have attempted to demonstrate the benefits associated with personalized antiplatelet therapy guided by platelet function testing, which has led to disappointing findings. In this study, we used a new platelet function test to guide antiplatelet therapy in stable coronary artery disease (CAD) patients after percutaneous coronary intervention (PCI).

Methods and results

In the present randomized controlled trial, a total of 2237 patients with stable CAD undergoing PCI were randomly chosen to be administered personalized antiplatelet therapy (personalized group; n = 1123) or standard antiplatelet treatment (standard group; n = 1114). The patients in the standard therapy group, without detecting the platelet aggregation rate, were administered a 75 mg/day clopidogrel maintenance dosage plus 100 mg/day of aspirin for at least 6 months after the procedure. For the patients in the personalized therapy group, the antiplatelet strategy was performed according to the maximum aggregation rate (MAR), determined using a novel platelet analyser, PL-12. If MAR &gt; 55%, 90 mg ticagrelor was administered twice daily plus 100 mg/day of aspirin after PCI. If MAR ≤55%, 75 mg/day clopidogrel plus 100 mg/day of aspirin was administered after PCI. The primary endpoint was net clinical adverse events, which were a composite of cardiac death, myocardial infarction, stroke, stent thrombosis, urgent revascularization, and bleeding [Bleeding Academic Research Consortium (BARC) definitions, Type 2, 3, or 5], in the 180-day period after randomization. The primary endpoint was reached in 58 patients in the personalized group, compared with 85 patients in the standard group [5.1% vs. 7.5%, hazard ratio (HR) 0.678, 95% confidence interval (CI) 0.486–0.947, P = 0.023], on intention-to-treat analysis. We also found that the net clinical adverse events (including ischaemic and bleeding events) were significantly reduced in the personalized group at 30 days after PCI compared to the standard group (1.5% vs. 3.0%, HR 0.510, 95% CI 0.284–0.915, P = 0.020). We did not find a significant difference in major bleeding events at either the 30-day (0.5% vs. 0.3%, P = 0.322) or the 180-day follow-up (2.1% vs. 1.6%, P = 0.364) between the two groups.

Conclusion

The present study suggests that personalized antiplatelet therapy according to MAR can significantly improve the net clinical benefit 180 days after PCI.

Impact of reduced-dose prasugrel vs. standard-dose clopidogrel on in-hospital outcomes of percutaneous coronary intervention in 62 737 patients with acute coronary syndromes: a nationwide registry study in Japan

Aims 

In Japan, reduced-dose prasugrel (loading/maintenance dose, 20/3.75 mg) has been approved for use in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI), because of the higher bleeding risk among East Asians. However, its safety in the real-world population has not been investigated. We aimed to evaluate the effectiveness and safety of reduced-dose prasugrel vs. standard-dose clopidogrel in ACS patients undergoing PCI.

Methods and results 

Acute coronary syndrome patients who underwent PCI in 2016, who were treated with either reduced-dose prasugrel or standard-dose clopidogrel in addition to aspirin, were identified from the nationwide Japanese PCI registry. The primary outcome was in-hospital mortality following PCI. Secondary outcomes included stent thrombosis and bleeding complication after PCI. Among 62 737 ACS patients who underwent PCI at any of 986 participating centres across Japan (clopidogrel 31.9%; prasugrel 68.1%), we identified 12 016 propensity score-matched pairs (24 032 patients; age 69.4 ± 12.2 years; female 24.9%; ST-elevation myocardial infarction 42.3%). Compared with standard-dose clopidogrel, reduced-dose prasugrel was associated with increased risk of bleeding [odds ratio (OR) 1.65, 95% confidence interval (CI) 1.10–2.51; P = 0.016], but both had similar rates of mortality (OR 1.11, 95% CI 0.89–1.38; P = 0.371) and stent thrombosis (OR 1.29, 95% CI 0.73–2.30; P = 0.387) as well as similar falsification endpoints of cardiac tamponade and emergent operation.

Conclusion 

In Japanese ACS patients undergoing PCI, the risk of bleeding is higher when using reduced-dose prasugrel than when using standard-dose clopidogrel, but there is no significant difference in in-hospital mortality and incidence of stent thrombosis between the two antiplatelet regimens.

Cost-effectiveness analysis of pharmacogenomics-guided clopidogrel treatment in Spanish patients undergoing percutaneous coronary intervention

Clopidogrel is an antiplatelet drug given to patients before and after having a percutaneous coronary intervention (PCI). Genomic variants in the CYP2C19 gene are associated with variable enzyme activities affecting drug metabolism and hence, patients with reduced or increased enzymatic function have increased risk of bleeding. We conducted a cost-effectiveness analysis to compare a pharmacogenomics versus a non-pharmacogenomics-guided clopidogrel treatment for coronary artery syndrome patients undergoing PCI in the Spanish healthcare setting. A total of 549 patients diagnosed with coronary artery disease followed by PCI were recruited. Dual antiplatelet therapy was administrated to all patients from 1 to 12 months after PCI. Patients were classified into two groups: the Retrospective group was treated with clopidogrel based on the clinical routine practice and the Prospective group were initially genotyped for the presence of CYP2C19 variant alleles before treatment with those carrying more than one CYP2C19 variant alleles given prasugrel treatment. We collected data on established clinical and health outcome measures, including, per treatment arm: the percentage of patients that suffered from (a) myocardial infraction, (b) major bleeding and minor bleeding, (c) stroke, (d) the number of hospitalization days, and (e) the number of days patients spent in Intensive Care Unit. Our primary outcome measure for the cost-effectiveness analysis was Quality Adjusted Life Years (QALYs). To estimate the treatment cost for each patient, individual data on its resource used were combined with unit price data, obtained from Spanish national sources. The analysis predicts a survival of 0.9446 QALYs in the pharmacogenomics arm and 0.9379 QALYs in the non-pharmacogenomics arm within a 1-year horizon. The cumulative costs per patient were €2971 and €3205 for the Prospective and Retrospective groups, respectively. The main cost driver of total cost in both arms was hospitalization costs. The incremental cost-effectiveness ratio (ICER) was negative indicating that the PGx was a dominant option. Our data show that pharmacogenomics-guided clopidogrel treatment strategy may represent a cost-effective choice compared with non-pharmacogenomics-guided strategy for patients undergoing PCI.

Does cardiology hold pharmacogenetics to an inconsistent standard? A comparison of evidence among recommendations

Current guideline recommendations for pharmacogenetic testing for clopidogrel by the American Heart Association/American College of Cardiology (AHA/ACC) contradict the Clinical Pharmacogenetics Implementation Consortium and the US FDA. The AHA/ACC recommends against routine pharmacogenetic testing for clopidogrel because no randomized controlled trials have demonstrated that testing improves patients' outcomes. However the AHA/ACC and the National Comprehensive Cancer Network (NCCN) recommend other pharmacogenetic tests in the absence of randomized controlled trials evidence. Using clopidogrel as a case example, we compared the evidence for other pharmacogenetic tests recommended by the AHA/ACC and NCCN. In patients that received percutaneous coronary intervention, the evidence supporting pharmacogenetic testing for clopidogrel is stronger than other pharmacogenetic tests recommended by the AHA/ACC and NCCN.

Clopidogrel-associated genetic variants on inhibition of platelet activity and clinical outcome for acute coronary syndrome patients

Acute coronary syndrome (ACS) has become a vital disease with high mortality worldwide. A combined antiplatelet therapy (aspirin and a P2Y₁₂ antagonist) is commonly used to prevent re-infarction in ACS patients who have undergone percutaneous coronary intervention (PCI). Clopidogrel, a P2Y₁₂ antagonist, plays an important role in the inhibition of platelet aggregation (IPA). However, it is a pro-drug requiring biotransformation by cytochrome P450 (CYP450). The aim of this study is to unravel the effect of clopidogrel-associated genetic variants on inhibition of platelet activity and clinical outcomes in ACS patients. In our study, a total of 196 patients with metabolic gene polymorphism of clopidogrel were enrolled, and their antiplatelet effect as well as their cardiovascular events were collected. Approximately 2 mL of venous blood samples were used for genotype detection and another 4 mL were collected for platelet reactivity with thrombelastography. The primary clinical end-point was defined as a combination of cardiovascular mortality and revascularization for targeted vascular lesion. Based on the results of IPA, the prevalence of high on-treatment platelet reactivity (HPR) was 17.3% and the majority of patients (82.7%) obtained normal on-treatment platelet reactivity (NPR). The HPR group had significantly higher body mass index (BMI) and lower arachidonic acid (AA) induced IPA (P < 0.05). Therapy including Glycoprotein (GP) IIb/IIIa antagonist increased IPA (P < 0.05). ADP-induced IPA effect was lower with the presence of CYP2C19*2, *3 and paraoxonase (PON)1 Q192R loss-of-function (LOF) alleles, respectively (P < 0.05). Multivariate logistic regression analysis demonstrated that aspirin resistance (AA-induced IPA < 50%) had a greater risk of the occurrence of major adverse cardiovascular events (MACE) (OR = 3.817; 95% CI: 1.672-8.700; P = 0.002). CYP2C19*2 LOF alleles were associated with high risk of MACE in 1-year post PCI operations (OR = 2.571; 95% CI: 1.143-5.780; P = 0.030). For the ACS patients, the presence of CYP2C19*2 and PON1 Q192R LOF alleles were the major drivers of HPR.