CYP2C19 genetic variation and individualized clopidogrel prescription in a cardiology clinic

Designing cytochrome P450 enzymes for use in cancer gene therapy

Cancer is a significant global socioeconomic burden, as millions of new cases and deaths occur annually. In 2020, almost 10 million cancer deaths were recorded worldwide. Advancements in cancer gene therapy have revolutionized the landscape of cancer treatment. An approach with promising potential for cancer gene therapy is introducing genes to cancer cells that encode for chemotherapy prodrug metabolizing enzymes, such as Cytochrome P450 (CYP) enzymes, which can contribute to the effective elimination of cancer cells. This can be achieved through gene-directed enzyme prodrug therapy (GDEPT). CYP enzymes can be genetically engineered to improve anticancer prodrug conversion to its active metabolites and to minimize chemotherapy side effects by reducing the prodrug dosage. Rational design, directed evolution, and phylogenetic methods are some approaches to developing tailored CYP enzymes for cancer therapy. Here, we provide a compilation of genetic modifications performed on CYP enzymes aiming to build highly efficient therapeutic genes capable of bio-activating different chemotherapeutic prodrugs. Additionally, this review summarizes promising preclinical and clinical trials highlighting engineered CYP enzymes' potential in GDEPT. Finally, the challenges, limitations, and future directions of using CYP enzymes for GDEPT in cancer gene therapy are discussed.

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.

Population genetic polymorphisms of pharmacogenes in Zimbabwe, a potential guide for the safe and efficacious use of medicines in people of African ancestry

OBJECTIVE

Pharmacogenomics (PGx) is a clinically significant factor in the safe and efficacious use of medicines. While PGx knowledge is abundant for other populations, there are scarce PGx data on African populations and is little knowledge on drug-gene interactions for medicines used to treat diseases common in Africa. The aim of this study was to use a custom-designed open array to genotype clinically actionable variants in a Zimbabwean population. This study also identified some of the commonly used drugs in Zimbabwe and the associated genes involved in their metabolism.

METHODS

A custom-designed open array that covers 120 genetic variants was used to genotype 522 black Zimbabwean healthy volunteers using TaqMan-based single nucleotide polymorphism genotyping. Data were also accessed from Essential Drugs' List in Zimbabwe (EDLIZ), and the medicines were grouped into the associated biomarker groups based on their metabolism. We also estimated the national drug procurement levels for medicines that could benefit from PGx-guided use based on the data obtained from the national authorities in Zimbabwe.

RESULTS

The results demonstrate the applicability of an open-array chip in simultaneously determining multiple genetic variants in an individual, thus significantly reducing cost and time to generate PGx data. There were significantly high frequencies of African-specific variants, such as the CYP2D6*17 and *29 variants and the CYP2B6*18 variant. The data obtained showed that the Zimbabwean population exhibits PGx variations in genes important for the safe and efficacious use of drugs approved by the EDLIZ and are procured at significantly large amounts annually. The study has established a cohort of genotyped healthy volunteers that can be accessed and used in the conduct of clinical pharmacogenetic studies for drugs entering a market of people of predominantly African ancestry.

CONCLUSION

Our study demonstrated the potential benefit of integrating PGx in Zimbabwe for the safe and efficacious use of drugs that are commonly used.

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.

Is monitoring of antiplatelet therapy by light transmission aggregometry dependent on instrument and reagent used?

INTRODUCTION

Light transmission aggregometry (LTA), used to detect clopidogrel resistance in patients under antiplatelet therapy, is prone to multiple variables potentially influencing results and interpretation. Currently, no attention is given to type of aggregometer or reagent used. The aim of this study was to evaluate the interassay variability between two aggregometers (Chronolog700 and TA-8V), using two different ADP reagents (Chrono-Par^® and Agro-Bio ADP) in patients under clopidogrel therapy. Additionally, LTA results were correlated to CYP2C19-polymorphism.

METHODS

Light transmission aggregometry was performed in 20 healthy individuals and 30 patients using both aggregometers, and applying two different reagents (2.5 and 5 µmol/L). The maximum platelet aggregation (ADP_max ), the platelet aggregation at 6 minutes (ADP_6min ), and the percentage of disaggregation at 6 min (ADP_%disaggr ) were compared between four applied combinations. Additionally, 23 clopidogrel-resistant patients according to Chronolog700-Chrono-par^® ADP reagent analysis were tested for CYP2C19*2 polymorphism.

RESULTS

Comparison of the LTA of healthy individuals revealed a significant lower ADP_max , lower ADP_6min , and higher ADP_%disaggr with the TA-8V aggregometer compared to Chronolog700, regardless of the reagent. In contrast, LTA results in patients are depending on the reagent, with significant higher ADP_max and ADP_6min and lower ADP_%disaggr using Chrono-Par^® compared to Agro-Bio ADP reagent. All intermediate clopidogrel metabolizers (CYP2C19*2 carriers) were correctly classified as clopidogrel resistant using Chrono-Par^® , in contrast to the Agro-Bio ADP reagent.

CONCLUSION

Light transmission aggregometry in clopidogrel-treated patients is mainly depending on the type of ADP reagent. Comparison of LTA with genotype reveals that the choice of instrument seems less influencing. In contrast, in the healthy individuals, differences could be attributed to the instrument.

Cytochrome P450 2C19 enzyme, Cytochrome P450 2C9 enzyme, and Cytochrome P450 2D6 enzyme allelic variants and its possible effect on drug metabolism: A retrospective study

ABSTRACT

The objective of the present study was to assess the allelic variations of Cytochrome P450 (CYP) enzymes Cytochrome P450 2C19 (CYP2C19), Cytochrome P450 2C9 (CYP2C9), and Cytochrome P450 2D6 (CYP2D6) as they play a major role in drug metabolism. The interindividual genetic variabilities of these enzymes can account for different responsiveness as well as concentration fluctuations for a particular drug.During the period of 2017 to 2018 a total of 54 patients have received pharmacogenetic testing at the Department of Genetics and Molecular Medicine at Kaunas Clinics. According to the genotype-metabolic phenotypes of CYP2C19, CYP2D6, CYP2C9 enzymes patients were classified according to the guidelines by Clinical Pharmacogenetics Implementation Consortium (CPIC): normal metabolizers (NMs), intermediate metabolizers (IMs), rapid metabolizers (RMs), ultrarapid metabolizers (UMs), and poor metabolizers (PMs).CYP2C19 enzyme allelic distribution: 18 patients (33.33%) with ∗1/∗1 genotype were NMs; 14 patients (25.93%) with ∗1/∗2; ∗2/∗17 genotypes were classified as IMs; 15 patients (27.78%) possessed ∗1/∗17 genotype and were RMs; 4 patients (7.4%) had ∗17/∗17 genotype with increased enzyme activity compared with RMs, were classified as UMs; 3 patients (5.56%) had ∗2/∗2 genotype and were marked as PMs. CYP2D6 enzyme allelic distribution: 26 patients (48.148%) contained ∗1/∗1,∗2/∗2,∗1/∗2,∗1/∗41,∗2/∗41 genotypes with normal enzymatic function so were accounted as NMs; 21 patients (38.89%) with ∗1/∗5, ∗2/∗4, ∗10/∗41, ∗1/∗4, ∗1/∗3, ∗2/∗5, ∗2/∗4, ∗2/∗6 genotypes were accounted as IMs; 2 patients (3.7%) possessed ∗2XN genotype and were accounted as UMs and 5 patients (9.26%) possessed ∗4/∗5,∗4/∗10,∗4/∗9,∗4/∗41 genotypes and had non-functional enzymatic activity so were accounted as PMs; CYP2C9 enzyme allelic distribution: 44 patients (81.48%) with∗1/∗1 genotype were NMs; 10 patients (18.52%) with ∗1/∗2;∗1/∗3 genotypes were IMs.The results of our study indicate that deviations from the normal enzymatic activity is common amongst Lithuanian people and combinatory genotyping of CYP2D6, CYP2C9, and CYP2C19 has to be promoted as an advanced method because of most commonly prescribed medicines like analgesics, antihypertensive, antidepressants are metabolized by multiple pathways involving enzymes in the CYP450 family.

Farmacogenômica e Doença Cardiovascular: Onde Estamos e Para Onde Vamos

A farmacogenômica (FGx) investiga a interação entre genes e medicamentos. Através da análise de regiões específicas do DNA, informações sobre o perfil de metabolização do paciente para um determinado fármaco podem ser descritas, assim como o perfil esperado de resposta ao tratamento. Objetivamente, esse tipo de teste pode ter impacto no tratamento de pacientes que não estão respondendo adequadamente a um determinado medicamento, seja pela ausência dos efeitos esperados ou em virtude do aparecimento de efeitos adversos. Neste cenário, o objetivo desta revisão é o de informar o cardiologista clínico sobre esta importante área do conhecimento e atualizá-lo sobre o tema, procurando preencher as lacunas no que diz respeito à relação custo-benefício da aplicação da FGx nas doenças cardiovasculares, além de fornecer informações para a implementação da terapia guiada pela FGx na prática clínica.

A Comprehensive Update on Aspirin Management During Noncardiac Surgery

Aspirin is considered critical lifelong therapy for patients with established cardiovascular (CV) disease (including coronary artery, cerebrovascular, and peripheral arterial diseases) and is consequently one of the most widely used medications worldwide. However, the indications for aspirin use continue to evolve and recent trials question its efficacy for primary prevention. Although one third of patients undergoing noncardiac surgery and at risk for a major adverse CV event receive aspirin perioperatively, uncertainty still exists about how aspirin should be optimally managed in this context, and significant practice variability remains. Recent trials suggest that the risks of continuing aspirin during the perioperative period outweigh the benefits in many cases, but data on patients with high CV risk remain limited. We performed a comprehensive PubMed and Medline literature search using the following keywords: aspirin, aspirin withdrawal, perioperative, coronary artery disease, cerebrovascular disease, peripheral artery disease, and CV disease; we manually reviewed all relevant citations for inclusion. Patients taking aspirin for the primary prevention of CV disease should likely discontinue it during the perioperative period, especially when there is a high risk of bleeding. Patients with established CV disease but without a coronary stent should likely continue aspirin during the perioperative period unless undergoing closed-space surgery. Patients with a history of coronary stenting also likely need aspirin continuation throughout the perioperative period for nonclosed space procedures. Perioperative clinicians need to balance the risks of ceasing aspirin before surgery against its continuation during the perioperative interval using a patient-specific strategy. The guidance on decision-making with regard to perioperative aspirin cessation or continuation using currently available clinical data from studies in high-risk patients along with nonclinical aspirin studies is conflicting and does not enable a simplified or unified answer. However, pertinent guidelines on CV disease management provide a basic framework for aspirin management, and large trial findings provide some insight into the safety of perioperative aspirin cessation in some contexts, although uncertainty on perioperative aspirin still exists. This review provides an evidence-based update on perioperative aspirin management in patients undergoing noncardiac surgery with a focus on recommendations for perioperative clinicians on continuing versus holding aspirin during this context.

Comparison of major bleeding in patients with acute coronary syndrome that underwent coronary artery bypass grafting treated with clopidogrel or ticagrelor: a systematic review and meta-analysis

Background: There is controversy among physicians regarding the use of dual antiplatelet therapy (DAPT) in acute coronary syndrome (ACS) patients treated with coronary artery bypass grafting (CABG). Moreover, the evidence of previous studies about this topic remained inconclusive. This study aimed to perform a meta-analysis concerning the relation between the risk of major bleeding and the use of different DAPT (clopidogrel or ticagrelor) in ACS patients treated with CABG. Methods: A meta-analysis was conducted during March to October 2019. Searches were carried out in Pubmed, Embase, Cochrane, and Web of Science. The predictor covariate in our present study was DAPT (clopidogrel or ticagrelor), and the outcome measure was the risk of major bleeding. Sub-group analysis was also performed, where data were classified into pre- and post-CABG. Furthermore, to determine the correlation and effect estimation, data were analyzed using fixed or random effect model. Results: A total of 13 studies consisting 34,015 patients treated with clopidogrel and 32,661 patients treated with ticagrelor was included in our study. Our pooled calculation revealed that the incidence of major bleeding was not different significantly between clopidogrel and ticagrelor. In pre- and post-CABG sub-groups, our results also found no significant difference in major bleeding incidence between clopidogrel and ticagrelor groups. Conclusions: Our meta-analysis clarifies that clopidogrel, compared to ticagrelor, or vice versa, is not associated with the risk of major bleeding in ACS patients treated with CABG.

Comparison of major bleeding in patients with acute coronary syndrome that underwent coronary artery bypass grafting treated with clopidogrel or ticagrelor: a systematic review and meta-analysis

Background: There is controversy among physicians regarding the use of dual antiplatelet therapy (DAPT) in acute coronary syndrome (ACS) patients treated with coronary artery bypass grafting (CABG). Moreover, the evidence of previous studies about this topic remained inconclusive. This study aimed to perform a meta-analysis concerning the relation between the risk of major bleeding and the use of different DAPT (clopidogrel or ticagrelor) in ACS patients treated with CABG. Methods: A meta-analysis was conducted during March to October 2019. Searches were carried out in Pubmed, Embase, Cochrane, and Web of Science. The predictor covariate in our present study was DAPT (clopidogrel or ticagrelor), and the outcome measure was the risk of major bleeding. Sub-group analysis was also performed, where data were classified into pre- and post-CABG. Furthermore, to determine the correlation and effect estimation, data were analyzed using fixed or random effect model. Results: A total of 13 studies consisting 34,015 patients treated with clopidogrel and 32,661 patients treated with ticagrelor was included in our study. Our pooled calculation revealed that the incidence of major bleeding was not different significantly between clopidogrel and ticagrelor. In pre- and post-CABG sub-groups, our results also found no significant difference in major bleeding incidence between clopidogrel and ticagrelor groups. Conclusions: Our meta-analysis clarifies that clopidogrel, compared to ticagrelor, or vice versa, is not associated with the risk of major bleeding in ACS patients treated with CABG.

Effects of different CYP2C19 genotypes on prognosis of patients complicated with atrial fibrillation taking clopidogrel after PCI

The effects of different cytochrome P450 2C19 (CYP2C19) genotypes on the prognosis of clopidogrel resistance in patients complicated with atrial fibrillation taking clopidogrel after percutaneous coronary intervention (PCI) were investigated. Eighty patients who were complicated with atrial fibrillation and treated with clopidogrel antiplatelet therapy after PCI in Meizhou Hospital Affiliated to Zhongshan University from September 2015 to January 2017 were selected, and divided into two groups according to the CYP2C19 genotype: extensive metabolism (EM) group and poor metabolism (PM) group. The related risk factors of clopidogrel resistance were determined, and the platelet aggregation rate and clopidogrel resistance rate were compared between the two groups during treatment. Non-fatal myocardial infarction and serious life-threatening complications in the two groups were observed. The increased total cholesterol level and the history of smoking and drinking were the independent risk factors of atrial fibrillation after PCI. The platelet aggregation rates in the EM group at 1, 3 and 12 months after medication were significantly lower than those in the PM group in the same period (P<0.05). The clopidogrel resistance rates in EM group before medication and at 1, 3 and 12 months after medication were higher than those in PM group in the same period (P<0.05). The onset time of non-fatal myocardial infarction in EM group was earlier than that in PM group (P<0.05), the infarct area was larger than that in PM group (P<0.05), and the left ventricular ejection fraction (EF) after onset was lower than that in PM group (P<0.05). In conclusion, the increased total cholesterol level and the history of smoking and drinking are the independent risk factors of clopidogrel resistance in patients complicated with atrial fibrillation after PCI. The incidence rates of cardiac complications are increased significantly in patients with PM CYP2C19 genotype.