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.

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.

Pharmacogenomic evaluation of CYP2C19 alleles linking low clopidogrel response and the risk of acute coronary syndrome in Indians.

BACKGROUND: Clopidogrel is an antiplatelet drug widely prescribed to prevent atherothrombotic events in coronary artery disease patients. However, there is evidence to suggest that the effectiveness of clopidogrel varies owing to genetic diversity in CYP2C19. This heterogeneity in South Asians, who are also known to have high risk of cardiac events than other population groups, highlights the importance of investigating CYP2C19 variants to estimate the risk proportion in the groups. METHODS: Given the high prevalence and genetic heterogeneity, the population-based case control was conducted in a cohort of 1191 subjects comprising 645 acute coronary syndrome (ACS) cases (unstable angina, ST-elevation myocardial infarction, and non-ST-elevation myocardial infarction) and 546 healthy controls of South Asian Indian origin. The metabolization status of CYP2C19 was assessed using *2, *3 and *17 variants in the stated cohorts to determine the prevalence of metabolization and its association with phenotypes. RESULTS: The results suggest a possible genetic association between studied CYP2C19 polymorphisms and ACS, since there was a higher proportion of intermediate and poor metabolizers present in the studied cohorts. The association analyses revealed that the *2 allele of CYP2C19 confers a significant risk for ACS, while the *17 allele provides protection. CONCLUSIONS: These findings contribute to the understanding of CYP2C19 genetic variants and their impact on clopidogrel response in South Asian Indians. Additionally, they underline the significance of assessing CYP2C19 variations in patients receiving clopidogrel therapy in order to improve therapeutic outcomes.

Precision medicine in cardiovascular therapeutics: Evaluating the role of pharmacogenetic analysis prior to drug treatment.

Pharmacogenomics is the examination of how genetic variation influences drug metabolism and response, in terms of both efficacy and safety. In cardiovascular disease, patient-specific diplotypes determine phenotypes, thereby influencing the efficacy and safety of drug treatments, including statins, antiarrhythmics, anticoagulants and antiplatelets. Notably, polymorphisms in key genes, such as CYP2C9, CYP2C19, VKORC1 and SLCO1B1, significantly impact the outcomes of treatment with clopidogrel, warfarin and simvastatin. Furthermore, the CYP2C19 polymorphism influences the pharmacokinetics and safety of the novel hypertrophic cardiomyopathy inhibitor, mavacamten. In this review, we critically assess the clinical application of pharmacogenomics in cardiovascular disease and delineate present and future utilization of pharmacogenomics. This includes insights into identifying missing heritability, the integration of whole genome sequencing and the application of polygenic risk scores to enhance the precision of personalized drug therapy. Our discussion encompasses health economic analyses that underscore the cost benefits associated with pre-emptive genotyping for warfarin and clopidogrel treatments, albeit acknowledging the need for further research in this area. In summary, we contend that cardiovascular pharmacogenomic analyses are underpinned by a wealth of evidence, and implementation is already occurring for some of these gene-drug pairs, but as with any area of medicine, we need to continually gather more information to optimize the use of pharmacogenomics in clinical practice.

A premature stop codon in the CYP2C19 gene may explain the unexpected sensitivity of vultures to diclofenac toxicity.

The unintended environmental exposure of vultures to diclofenac has resulted in the deaths of millions of old-world vultures on the Asian subcontinent. While toxicity has been since associated with a long half-life of elimination and zero order metabolism, the actual constraint in biotransformation is yet to be clarified. For this study we evaluated if the evident zero order metabolism could be due to defects in the CYP2C9/2C19 enzyme system. For this, using whole genome sequencing and de-novo transcriptome alignment, the vulture CYP2C19 open reading frame was identified through Splign analysis. The result sequence analysis revealed the presence of a premature stop codon on intron 7 of the identified open reading frame. Even if the stop codon was not present, amino acid residue analysis tended to suggest that the enzyme would be lower in activity than the equivalent human enzyme, with differences present at sites 105, 286 and 289. The defect was also conserved across the eight non-related vultures tested. From these results, we conclude that the sensitivity of the old-world vultures to diclofenac is due to the non-expression of a viable CYP2C19 enzyme system. This is not too dissimilar to the effects seen in certain people with a similar defective enzyme.

Individualized treatment with voriconazole in the Chinese population: Inflammation level as a novel marker for dose optimization.

AIMS: The aim of this study was to explore the influence and possible mechanisms of pharmacokinetics-related gene polymorphisms, especially CYP2C19 polymorphisms, and non-genetic factors combined with the inflammatory status on the voriconazole (VRC) metabolism of the Chinese population. METHODS: Clinical studies were performed by collecting more than one VRC trough concentration and C-reactive protein (CRP) level. A total of 265 blood samples were collected from 120 patients. RESULTS: Results of multiple regression analyses demonstrated that CYP2C19 genotypes and albumin (Alb) level remained predictors of Cmin ss/D in patients with no to mild inflammation (R2 = 0.12, P < .001). In addition, in patients with moderate to severe inflammation, it resulted in a significant model containing factors of CRP and total bilirubin (T-Bil) levels (R2 = 0.19, P < .001). In non-clinical studies, 32 rats were divided into control and inflammatory groups, and it was found that the mean residence time (MRT(0-t) ) of VRC in the inflammatory group was significantly longer than that in the control group (P < .001), which may be due to down-regulation of mRNA and protein expression of CYP2C19 (CYP2C6 in rats) through interleukin (IL)-6/signal transducer and activator of transcription (STAT) 3 pathway. CONCLUSIONS: Therefore, the effect of CYP2C19 polymorphisms on VRC metabolism may be masked by inflammatory status, which should be of more concern than CYP2C19 polymorphisms in patients with moderate to severe inflammation. Additionally, the impact of Alb and T-Bil on VRC metabolism should not be disregarded.

Combined effect of CYP2C19 and CYP2D6 genotypes on escitalopram serum concentration and its metabolic ratio in a European patient population.

AIMS: The aim of the present study was to investigate the impact of CYP2D6 genotype on exposure and metabolism of escitalopram in patients stratified by CYP2C19 genotype in a large real-world population. METHODS: Patients were included from a therapeutic drug monitoring service if they had measured serum concentration of escitalopram and the metabolite, N-desmethyl escitalopram, and performed CYP2C19 and CYP2D6 genotyping. Patients were divided into 16 combined genotype-predicted phenotype subgroups (poor [PM], intermediate [IM], normal [NM] and ultrarapid metabolizers [UM]) of CYP2C19/CYP2D6. The concentration-to-dose (CD) ratio and metabolite-to-parent ratio (metabolic ratio) of escitalopram were compared across subgroups using the Kruskal-Wallis test followed by Dunn's test with CYP2D6 NMs as the reference group. RESULTS: A total of 5067 patients were included in the study. A stepwise increase in escitalopram CD ratio by decreasing CYP2D6 activity was observed in all CYP2C19 subgroups, except for in CYP2C19 UMs. The percentage differences in escitalopram CD ratio between CYP2D6 PMs and NMs were 24% in CYP2C19 NMs (P < .001), 28% in CYP2C19 IMs (P < .001) and 31% in CYP2C19 PMs (P = .04). As for the CD ratio, CYP2D6 genotype effect on metabolic ratio increased stepwise by decreasing CYP2C19 metabolism. CONCLUSIONS: CYP2D6 genotype is of significant importance for the individual variation in escitalopram pharmacokinetics. The most relevant increase in escitalopram concentration is seen in individuals with decreased and/or absent CYP2C19 activity. By combining CYP2C19 and CYP2D6 genotypes, the optimal dose for patients may be predicted with greater precision than for CYP2C19 genotype alone.

Physiologically Based Pharmacokinetic Modeling to Unravel the Drug-gene Interactions of Venlafaxine: Based on Activity Score-dependent Metabolism by CYP2D6 and CYP2C19 Polymorphisms.

BACKGROUND: Venlafaxine (VEN) is a commonly utilized medication for alleviating depression and anxiety disorders. The presence of genetic polymorphisms gives rise to considerable variations in plasma concentrations across different phenotypes. This divergence in phenotypic responses leads to notable differences in both the efficacy and tolerance of the drug. PURPOSE: A physiologically based pharmacokinetic (PBPK) model for VEN and its metabolite O-desmethylvenlafaxine (ODV) to predict the impact of CYP2D6 and CYP2C19 gene polymorphisms on VEN pharmacokinetics (PK). METHODS: The parent-metabolite PBPK models for VEN and ODV were developed using PK-Sim® and MoBi®. Leveraging prior research, derived and implemented CYP2D6 and CYP2C19 activity score (AS)-dependent metabolism to simulate exposure in the drug-gene interactions (DGIs) scenarios. The model's performance was evaluated by comparing predicted and observed values of plasma concentration-time (PCT) curves and PK parameters values. RESULTS: In the base models, 91.1%, 94.8%, and 94.6% of the predicted plasma concentrations for VEN, ODV, and VEN + ODV, respectively, fell within a twofold error range of the corresponding observed concentrations. For DGI scenarios, these values were 81.4% and 85% for VEN and ODV, respectively. Comparing CYP2D6 AS = 2 (normal metabolizers, NM) populations to AS = 0 (poor metabolizers, PM), 0.25, 0.5, 0.75, 1.0 (intermediate metabolizers, IM), 1.25, 1.5 (NM), and 3.0 (ultrarapid metabolizers, UM) populations in CYP2C19 AS = 2.0 group, the predicted DGI AUC0-96 h ratios for VEN were 3.65, 3.09, 2.60, 2.18, 1.84, 1.56, 1.34, 0.61, and for ODV, they were 0.17, 0.35, 0.51, 0.64, 0.75, 0.83, 0.90, 1.11, and the results were similar in other CYP2C19 groups. It should be noted that PK differences in CYP2C19 phenotypes were not similar across different CYP2D6 groups. CONCLUSIONS: In clinical practice, the impact of genotyping on the in vivo disposition process of VEN should be considered to ensure the safety and efficacy of treatment.

The Impact of CYP2C19 Genotype on the Platelet Reactivity Index (PRI) among Chronic Coronary Syndromes (CCS) Patients Undergoing Percutaneous Coronary Intervention (PCI): Affectability of Rapid Genetic Testing.

BACKGROUND: In the Asian population, the presence of the CYP2C19 loss-of-function (LOF) allele is a known genetic variation. This allele is associated with a reduced capacity to metabolize clopidogrel into its active forms through the CYP2C19 enzyme, resulting in diminished platelet inhibition and an elevated risk of recurrent cardiovascular events. Regulatory authorities have recommended an alternative P2Y12 inhibitor, ticagrelor, for individuals carrying the LOF allele. Consequently, this study seeks to assess the impact of the CYP2C19 genotype on the Platelet reactivity index (PRI) using a rapid genetic testing approach in Asian patients with chronic coronary syndromes (CCS) who undergo percutaneous coronary intervention (PCI). METHODS: This prospective study employed a parallel design, single-center design, and randomized approach. Genotyping for the CYP2C19*2 and *3 polymorphisms was conducted using the Nested Allele-Specific Multiplex PCR (NASM-PCR) technique. Patients meeting the inclusion criteria underwent genotyping for CYP2C19 polymorphisms. Following PCI, patients were randomly assigned to receive either ticagrelor or clopidogrel. PRI assessments were performed four hours after loading dose administration. The trial was registered with ClinicalTrials.gov under the identifier NCT05516784. RESULTS: Among the 94 patients recruited for the study, 40 (42.55%) were identified as carriers of the LOF allele for CYP2C19*2 and *3 (*1/*2, *2/*2, *1/*3). Out of the 84 patients evaluated for PRI (44 receiving clopidogrel and 40 receiving ticagrelor), 21 (47.7%) of the clopidogrel group and 39 (97.5%) of the ticagrelor group exhibited a favorable response to antiplatelet therapy (PRI < 50). Patients treated with ticagrelor demonstrated superior antiplatelet responses compared to those receiving clopidogrel, regardless of LOF carrier status (P = 0.005 and < 0.001 for non-LOF and LOF carriers, respectively). CONCLUSION: NASM-PCR as a rapid genetic test holds promise for personalizing antiplatelet therapy in Asian CCS patients.

Association of CYP2D6 and CYP2C19 metabolizer status with switching and discontinuing antidepressant drugs: an exploratory study.

BACKGROUND: Tailoring antidepressant drugs (AD) to patients' genetic drug-metabolism profile is promising. However, literature regarding associations of ADs' treatment effect and/or side effects with drug metabolizing genes CYP2D6 and CYP2C19 has yielded inconsistent results. Therefore, our aim was to longitudinally investigate associations between CYP2D6 (poor, intermediate, and normal) and CYP2C19 (poor, intermediate, normal, and ultrarapid) metabolizer-status, and switching/discontinuing of ADs. Next, we investigated whether the number of perceived side effects differed between metabolizer statuses. METHODS: Data came from the multi-site naturalistic longitudinal cohort Netherlands Study of Depression and Anxiety (NESDA). We selected depression- and/or anxiety patients, who used AD at some point in the course of the 9 years follow-up period (n = 928). Medication use was followed to assess patterns of AD switching/discontinuation over time. CYP2D6 and CYP2C19 alleles were derived using genome-wide data of the NESDA samples and haplotype data from the PharmGKB database. Logistic regression analyses were conducted to investigate the association of metabolizer status with switching/discontinuing ADs. Mann-Whitney U-tests were conducted to compare the number of patient-perceived side effects between metabolizer statuses. RESULTS: No significant associations were observed of CYP metabolizer status with switching/discontinuing ADs, nor with the number of perceived side effects. CONCLUSIONS: We found no evidence for associations between CYP metabolizer statuses and switching/discontinuing AD, nor with side effects of ADs, suggesting that metabolizer status only plays a limited role in switching/discontinuing ADs. Additional studies with larger numbers of PM and UM patients are needed to further determine the potential added value of pharmacogenetics to guide pharmacotherapy.

Modeled Hepatic/Plasma Exposures of Omeprazole Prescribed Alone in Cytochrome P450 2C19 Poor Metabolizers Are Likely Associated with Hepatic Toxicity Reported in a Japanese Adverse Event Database.

Omeprazole, a gastric acid pump inhibitor, is repeatedly administered and is oxidatively metabolized mainly by polymorphic cytochrome P450 2C19. The prescribed dosage of omeprazole was discontinued or reduced in 47 of the 135 patients who received omeprazole alone in this survey, as recorded in the Japanese Adverse Drug Event Report database. The days to onset of omeprazole-related disorders were 3-4 d (median) and 16 d for intravenous 20-40 mg and oral 20 mg daily doses, respectively, in 34 patients for whom relevant data were available. The maximum plasma concentration of omeprazole was pharmacokinetically modeled after a single oral 40-mg dose in P450 2C19-defective poor metabolizers and was 2.4-fold higher than that in extensive metabolizers. The modeled area under the hepatic concentration curves of omeprazole in P450 2C19 poor metabolizers after virtual daily 40-mg doses for 7 d was 5.2-fold higher than that in the extensive metabolizers. Omeprazole-induced P450 2C19 (approx. 2-fold), resulting in increased hepatic intrinsic clearance in repeated doses, was considered after the second day. Virtual plasma/hepatic exposure estimated using pharmacokinetic modeling in subjects with P450 2C19 poor metabolizers indicated that these exposure levels virtually estimated could be one of causal factors for unexpected hepatic disorders induced by prescribed omeprazole, such as those resulting from drug interactions with repeatedly co-administered medicines.

Development of a routine bedside CYP2C19 genotype assessment program for antiplatelet therapy guidance in a community hospital catheterization laboratory.

Genotype based personalized antiplatelet therapy in the setting of percutaneous coronary intervention (PCI) has been studied in clinical trials. Despite the demonstrated risk associated with CYP2C19 loss-of-function (LoF) carriage in clopidogrel-treated PCI patients, real-world implementation of genotyping for PCI has been low. The goal of the current study was to provide CYP2C19 genotype information to the interventionalist prior to the completion of the catheterization to facilitate immediate personalized antiplatelet therapy. Routine personalization of P2Y12 inhibitor therapy for PCI in a community hospital cardiac catheterization laboratory by POC genotyping with the SpartanRx system was first offered in February 2017. A best practice advisory (BPA) based on the Clinical Pharmacogenetics Implementation Consortium Guideline for CYP2C19 genotype and clopidogrel therapy was placed in the electronic health record prescription medication ordering system. By December 2019, 1,052 patients had CYP2C19 genotype testing, 429 patients underwent PCI with genotype guided antiplatelet therapy, and 250 patients underwent PCI without genotype testing and received antiplatelet therapy at the discretion of the treating physician. BPA compliance was 93. 87% of LoF allele carriers were prescribed ticagrelor or prasugrel whereas 96% of non-LoF allele carriers were prescribed clopidogrel. The genotyping results were available within 1 h and made immediately available for decision making by the interventional cardiologist. POC CYP2C19 genotyping is feasible in a community hospital catheterization laboratory and is associated with high rate of best practice compliance.Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT03040622.

Influence of CYP2C19, CYP2D6, and ABCB1 Gene Variants and Serum Levels of Escitalopram and Aripiprazole on Treatment-Emergent Sexual Dysfunction: A Canadian Biomarker Integration Network in Depression 1 (CAN-BIND 1) Study.

OBJECTIVES: Treatment-emergent sexual dysfunction is frequently reported by individuals with major depressive disorder (MDD) on antidepressants, which negatively impacts treatment adherence and efficacy. We investigated the association of polymorphisms in pharmacokinetic genes encoding cytochrome-P450 drug-metabolizing enzymes, CYP2C19 and CYP2D6, and the transmembrane efflux pump, P-glycoprotein (i.e., ABCB1), on treatment-emergent changes in sexual function (SF) and sexual satisfaction (SS) in the Canadian Biomarker Integration Network in Depression 1 (CAN-BIND-1) sample. METHODS: A total of 178 adults with MDD received treatment with escitalopram (ESC) from weeks 0-8 (Phase I). At week 8, nonresponders were augmented with aripiprazole (ARI) (i.e., ESC + ARI, n = 91), while responders continued ESC (i.e., ESC-Only, n = 80) from weeks 8-16 (Phase II). SF and SS were evaluated using the sex effects (SexFX) scale at weeks 0, 8, and 16. We assessed the primary outcomes, SF and SS change for weeks 0-8 and 8-16, using repeated measures mixed-effects models. RESULTS: In ESC-Only, CYP2C19 intermediate metabolizer (IM) + poor metabolizers (PMs) showed treatment-related improvements in sexual arousal, a subdomain of SF, from weeks 8-16, relative to CYP2C19 normal metabolizers (NMs) who showed a decline, F(2,54) = 8.00, p < 0.001, q = 0.048. Specifically, CYP2C19 IM + PMs reported less difficulty with having and sustaining vaginal lubrication in females and erection in males, compared to NMs. Furthermore, ESC-Only females with higher concentrations of ESC metabolite, S-desmethylcitalopram (S-DCT), and S-DCT/ESC ratio in serum demonstrated more decline in SF (r = -0.42, p = 0.004, q = 0.034) and SS (r = -0.43, p = 0.003, q = 0.034), respectively, which was not observed in males. ESC-Only females also demonstrated a trend for a correlation between S-DCT and sexual arousal change in the same direction (r = -0.39, p = 0.009, q = 0.052). CONCLUSIONS: CYP2C19 metabolizer phenotypes may be influencing changes in sexual arousal related to ESC monotherapy. Thus, preemptive genotyping of CYP2C19 may help to guide selection of treatment that circumvents selective serotonin reuptake inhibitor-related sexual dysfunction thereby improving outcomes for patients. Additionally, further research is warranted to clarify the role of S-DCT in the mechanisms underlying ESC-related changes in SF and SS. This CAN-BIND-1 study was registered on clinicaltrials.gov (Identifier: NCT01655706) on 27 July 2012.

Pharmacogenetic implementation for CYP2C19 and pharmacokinetics of voriconazole in children with malignancy or inborn errors of immunity.

BACKGROUND: Voriconazole pharmacokinetics (PK) are known to be affected by genetic polymorphisms of drug-metabolizing enzymes such as CYP2C19; however, such information is limited for the pediatric population. The primary aim of this study is to establish a voriconazole PK model incorporating CYP2C19 phenotypes in Japanese children with malignancy or inborn errors of immunity. METHODS: CYP2C19 genotypes were assessed by whole-genome genotyping and defined as follows: *17/*17: ultrarapid metabolizer (URM), *1/*17: rapid metabolizer (RM), *1/*1:normal metabolizer (NM), *1/*2, *1/*3, *2/*17:intermediate metabolizer (IM), and *2/*2, *2/*3, *3/*3: poor metabolizer (PM). Population PK analysis was performed. The voriconazole serum concentration profile was described by a two-compartment model with first-order absorption, mixed linear and nonlinear (Michaelis-Menten) elimination. RESULTS: Voriconazole concentration data were available from 60 patients with a median age of 5.3 years. The phenotypes predicted from CYP2C19 genotypes were RM in 1 (2 %), NM in 21 (35 %) patients, IM in 27 (45 %) patients, and PM in 11 (18 %) patients. Underlying diseases included 38 (63%) patients with hematological malignancy and 18 (30 %) patients with inborn errors of immunity. Among the CYP2C19 phenotypes, PM was predicted to show complete inhibition (the degree of Vmax inhibition [Vmax, inh] = 100 %; Vmax = 0). The estimated parameters of Vmax,inh were +0.8 higher in patients with gamma-glutamyl transpeptidase (γ-GTP) Grade 2 or higher and +2.7 higher when C-reactive protein (CRP) levels were 2.0 mg/dL or higher. CONCLUSION: CYP2C19 genetic polymorphisms, γ-GTP, and CRP affect Vmax,inh of voriconazole in children with malignancy or inborn errors of immunity.

Clustering plasma concentration-time curves: applications of unsupervised learning in pharmacogenomics.

Pharmaceutical researchers are continually searching for techniques to improve both drug development processes and patient outcomes. An area of recent interest is the potential for machine learning (ML) applications within pharmacology. One such application not yet given close study is the unsupervised clustering of plasma concentration-time curves, hereafter, pharmacokinetic (PK) curves. In this paper, we present our findings on how to cluster PK curves by their similarity. Specifically, we find clustering to be effective at identifying similar-shaped PK curves and informative for understanding patterns within each cluster of PK curves. Because PK curves are time series data objects, our approach utilizes the extensive body of research related to the clustering of time series data as a starting point. As such, we examine many dissimilarity measures between time series data objects to find those most suitable for PK curves. We identify Euclidean distance as generally most appropriate for clustering PK curves, and we further show that dynamic time warping, Fréchet, and structure-based measures of dissimilarity like correlation may produce unexpected results. As an illustration, we apply these methods in a case study with 250 PK curves used in a previous pharmacogenomic study. Our case study finds that an unsupervised ML clustering with Euclidean distance, without any subject genetic information, is able to independently validate the same conclusions as the reference pharmacogenomic results. To our knowledge, this is the first such demonstration. Further, the case study demonstrates how the clustering of PK curves may generate insights that could be difficult to perceive solely with population level summary statistics of PK metrics.

Effect of MDR1 C3435T and CYP2C19 genetic polymorphisms on the outcome of Helicobacter pylori eradication treatment in children with gastritis and peptic ulcer, Vietnam.

BACKGROUND: Helicobacter pylori eradication therapy based on antimicrobial susceptibility in Vietnamese children currently get low efficiency. There are causes of treatment failure, among host genetic factors namely MDR1 C3435T and CYP2C19 affect the absorption and metabolism of proton pump inhibitors - a crucial component of eradication therapy. The study aimed to investigate the effect of MDR1 C3435T and CYP2C19 genetic polymorphisms on the cure rate. METHODS: 207 pediatric patients with gastritis and peptic ulcer infecting Helicobacter pylori completed the eradication therapy based on antimicrobial susceptibility with proton pump inhibitor esomeprazole. Eradication efficacy was assessed after at least 4 weeks by the urease breath test. MDR1 C3435T genetic polymorphism and CYP2C19 genotype were determined using a sequencing method based on Sanger's principle. RESULTS: Among 207 children recruited in this study, the ratio of CYP2C19 EM, IM, and PM phenotypes was 40.1%, 46.4%, and 16.9%, respectively. The patient with MDR1 3435 C/C polymorphism accounted for 43.0%, MDR1 3435 C/T was 40.1%, and MDR1 3435T/T was 16.9%. The cure rate of Helicobacter pylori infection in patients with CYP2C19 EM genotype was 78.3%; 83.3% of those with the IM genotype, and PM genotype was 96,4% (p = 0.07). Successful eradication rates for Helicobacter pylori were 85.4%, 86.7%, and 68.6% in patients with the MDR1 3435 C/C, C/T, and T/T, respectively (p = 0.02). Multiple logistic regression analysis found that MDR1 C3435T genetic polymorphisms of patients were significant independent risk factors for treatment failure, and CYP2C19 genotype did not affect Helicobacter pylori eradication. CONCLUSIONS: The Helicobacter pylori eradication rates by regimens based on antibiotic susceptibility and esomeprazole were not significantly different between the CYP2C19 phenotypes. The MDR1 C3435T polymorphism is one of the factors impacting Helicobacter pylori eradication results in children.

Influencing risk factors of voriconazole-induced liver injury in Uygur pediatric patients undergoing allogeneic hematopoietic stem cell transplantation.

PURPOSE: We aimed to investigated the influencing risk factors of voriconazole-induced liver injury in Uygur pediatric patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT). METHODS: This was a prospective cohort design study. High-performance liquid chromatography-mass spectrometry was employed to monitor voriconazole concentration. First-generation sequencing was performed to detect gene polymorphisms. Indicators of liver function were detected at least once before and after voriconazole therapy. RESULTS: Forty-one patients were included in this study, among which, 15 patients (36.6%) had voriconazole-induced liver injury. The proportion of voriconazole trough concentration > 5.5 µg·mL-1 patients within the DILI group (40.0%) was significantly higher compared to the control group (15.4%) (p < 0.05). After administration of voriconazole, the values of ALT (103.3 ± 80.3 U/L) and AST (79.9 ± 60.6 U/L) in the DILI group were higher than that in the control group (24.3 ± 24.8 and 30.4 ± 8.6 U/L) (p < 0.05). There was no significant difference between the two groups in genotype and allele frequencies of CYP2C19*2, CYP2C19*3, CYP2C19*17, and UGT1A4 (rs2011425) (p > 0.05). CONCLUSION: There was a significant correlation between voriconazole-induced liver injury and voriconazole trough concentration in high-risk Uygur pediatric patients with allogeneic HSCT.

Clinician perspectives regarding CYP2C19 genotype testing in patients with critical limb ischemia: A Delphi approach.

OBJECTIVES: Antiplatelet therapy is an essential element in the management of patients with arterial vascular disease. In peripheral arterial disease (PAD), dual antiplatelet therapy (DAPT), primarily clopidogrel and aspirin, is routinely prescribed following intervention. There is sparse data regarding the need for DAPT, the appropriate duration, or the heterogeneity of treatment effects for antiplatelet regimens across patients, leading to potential uncertainty and heterogeneity around treatment practices. An example of heterogeneity of treatment effects is a patients' metabolizer status for the use of clopidogrel. The aim of the study was to (1) assess clinicians' knowledge of and attitudes toward managing patients with CYP2C19 mutations, (2) identify barriers to implementation of CYP2C19 testing and management policies, and (3) reach consensus for CYP2C19 testing and management strategies for patients with PAD who undergo peripheral vascular interventions (PVI). METHODS: A modified Delphi method was used to establish consensus amongst PAD interventionalists around CYP2C19 testing. All practicing Yale New Haven Hospital PAD interventionalists with backgrounds in interventional cardiology, vascular surgery, or interventional radiology were approached by email for participation. Round 1 included the collection of baseline demographic questions, knowledge questions, and three statements for consensus. Knowledge questions were rated on a 0-10 Likert scale with the following anchors: 0 ("Not at all"), 5 ("Neutral), and 10 ("Very Much"). Participants were asked to rate the importance of the three consensus statements on a 9-point Likert scale from 1 ("Strongly Disagree") to 10 ("Strongly Agree"). In Round 2, participants were shown the same consensus statements, the median response of the group from the previous round, and their previous answers. Participants were instructed to revise their rating using the results from the previous round. This process was repeated for Round 3. RESULTS: Of the 28 experts invited to participate, 13 agreed (46%). Participants were predominantly male (92.3%) and white (61.5%) with representation from interventional cardiology (46.2%) and vascular surgery (53.8%). Most participants reported more than 10+ years in practice (61.5%). PAD interventionalists felt they would benefit from more education regarding CYP2C19 mutations (median score 8.0, interquartile range 5.0-8.5). They indicated some familiarity with CYP2C19 mutations (7.0, 6.0-9.5) but did not feel strongly that CYP2C19 was important to their practice (6.0, 5.5-7.5). In each round, the median responses for the three consensus statements were 5, 6, and 9, respectively. With each successive round the interquartile range narrowed indicative of evolving consensus but did not reach the prespecified interquartile range for consensus of 1 for any of the statements. CONCLUSIONS: PAD interventionalists practicing at an academic health system recognize the heterogenous response of their patients to clopidogrel therapy but are unsure when to leverage genetic testing to improve outcomes for their patients. Our study identified gaps regarding PAD interventionalists' knowledge, perceived barriers, and attitudes toward CYP2C19 testing in PAD. This information highlights the need for randomized data on genetic testing for clopidogrel responsiveness in peripheral vascular disease following intervention to help guide antiplatelet management.

Impact of STAT6 Variants on the Response to Proton Pump Inhibitors and Comorbidities in Patients with Eosinophilic Esophagitis.

Proton pump inhibitors (PPIs) are the first-line drug for eosinophilic esophagitis (EoE), although it is estimated that there is a lack of histological remission in 50% of patients. This research aimed to identify pharmacogenetic biomarkers predictive of PPI effectiveness and to study their association with disease features. Peak eosinophil count (PEC) and the endoscopic reference score (EREFS) were determined before and after an eight-week PPI course in 28 EoE patients. The impact of the signal transducer and activator of transcription 6 (STAT6), CYP2C19, CYP3A4, CYP3A5, and ABCB1 genetic variations on baseline PEC and EREFS, their reduction and histological response, and on EoE symptoms and comorbidities was analyzed. PEC reduction was higher in omeprazole-treated patients (92.5%) compared to other PPIs (57.9%, p = 0.003). STAT6 rs12368672 (g.18453G>C) G/G genotype showed higher baseline PEC values compared to G/C and C/C genotypes (83.2 vs. 52.9, p = 0.027). EREFS reduction in STAT6 rs12368672 G/G and G/C genotypes was higher than in the C/C genotype (36.7% vs. -75.0% p = 0.011). However, significance was lost after Bonferroni correction. Heartburn incidence was higher in STAT6 rs167769 (g.27148G>A) G/G patients compared to G/A (54.55% vs. 11.77%, p = 0.030). STAT6 rs12368672G>C and rs167769G>A variants might have a relevant impact on EoE status and PPI response. Further research is warranted to clarify the clinical relevance of these variants.

Impact of CYP2C19 Gene Variants on Long-Term Treatment with Atorvastatin in Patients with Acute Coronary Syndromes.

The effectiveness of lipid-lowering therapies may be insufficient in high-risk cardiovascular patients and depends on the genetic variability of drug-metabolizing enzymes. Customizing statin therapy, including treatment with atorvastatin, may improve clinical outcomes. Currently, there is a lack of guidelines allowing the prediction of the therapeutic efficacy of lipid-lowering statin therapy. This study aimed to determine the effects of clinically significant gene variants of CYP2C19 on atorvastatin therapy in patients with acute coronary syndromes. In total, 92 patients with a confirmed diagnosis of ST-elevation myocardial infarction (STEMI) or non-ST-elevation myocardial infarction (NSTEMI) were sequenced for target regions within the CYP2C19 gene on the Illumina Miniseq system. The CYP2C19 poor metabolizer phenotype (carriers of CYP2C19*2, CYP2C19*4, and CYP2C19*8 alleles) was detected in 29% of patients. These patients had significantly lower responses to treatment with atorvastatin than patients with the normal metabolizer phenotype. CYP2C19-metabolizing phenotype, patient age, and smoking increased the odds of undertreatment in patients (∆LDL-C (mmol/L) < 1). These results revealed that the CYP2C19 phenotype may significantly impact atorvastatin therapy personalization in patients requiring LDL lipid-lowering therapy.