CYP2C19 Single Nucleotide Polymorphisms Research Articles

Integration of CRISPR/Cas13a and V-Shape PCR for Rapid, Sensitive, and Specific Genotyping of CYP2C19 Gene Polymorphisms.

Rapid detection of single nucleotide polymorphisms (SNPs) in the CYP2C19 gene is of great significance for clopidogrel-accurate medicine. CRISPR/Cas systems have been increasingly used in SNP detection due to their single-nucleotide mismatch specificity. PCR, as a powerful amplification tool, has been incorporated into the CRISPR/Cas system to improve the sensitivity. However, the complicated three-step temperature control of the conventional PCR impeded rapid detection. The "V" shape PCR can shorten about 2/3 of the amplification time compared with conventional PCR. Herein, we present a new system termed the "V" shape PCR-coupled CRISPR/Cas13a (denoted as VPC) system, achieving the rapid, sensitive, and specific genotyping of CYP2C19 gene polymorphisms. The wild- and mutant-type alleles in CYP2C19*2, CYP2C19*3, and CYP2C19*17 genes can be discriminated by using the rationally programmed crRNA. A limit of detection (LOD) of 102 copies/μL was obtained within 45 min. In addition, the clinical applicability was demonstrated by genotyping SNPs in CYP2C19*2, CYP2C19*3, and CYP2C19*17 genes from clinical blood samples and buccal swabs within 1 h. Finally, we conducted the HPV16 and HPV18 detections to validate the generality of the VPC strategy.

Genetic Polymorphisms in CYP2C19 Cause Changes in Plasma Levels and Adverse Reactions to Anlotinib in Chinese Patients With Lung Cancer.

Background: Anlotinib is a small molecular multi-targeting tyrosine kinase inhibitor. Growing evidence indicates that treatment efficacy, and toxicity varies considerably between individuals. Therefore, this study aimed to investigate the relationship between cytochrome P450 (CYP450) gene polymorphisms, drug concentrations, and their adverse reactions in anlotinib-treated patients with lung cancer. Methods: We enrolled 139 patients with lung cancer, treated with anlotinib. Twenty loci in the following five genes of the CYP450 family were genotyped: CYP450 family 3 subfamily A member 5 (CYP3A5), 3 subfamily A member 4 (CYP3A4), 2 subfamily C member 9 (CYP2C9), 2 subfamily C member 19 (CYP2C19), and 1 subfamily A member 2 (CYP1A2). Data on adverse reactions were collected from patients, and plasma anlotinib concentrations were measured. Results: There were significant variances in plasma trough concentration (3.95–52.88 ng/ml) and peak plasma concentration (11.53–42.8 ng/ml) following administration of 8 mg anlotinib. Additionally, there were significant differences in the plasma trough concentration (5.65–81.89 ng/ml) and peak plasma concentration (18.01–107.18 ng/ml) following administration of 12 mg anlotinib. Furthermore, for CYP2C19-rs3814637, the peak plasma concentrations of mutant allele T carriers (TT+CT) were significantly higher than those of wildtypes (CC). For CYP2C19-rs11568732, the peak plasma concentrations of the mutant allele G carriers (GT+GG) were significantly higher than those of the wild-type (TT). More importantly, the incidence rates of hypertension and hemoptysis (peripheral lung cancer) with TT+CT in rs3814637 and GT+GG in rs11568732 were significantly higher than those with CC and TT. Conclusions: The plasma trough and peak concentrations varied significantly for both 8 and 12 mg of anlotinib. Single-nucleotide polymorphisms in CYP2C19 are significantly associated with hypertension, hemoptysis, and anlotinib peak concentrations. Polymorphisms in CYP450 may explain inter-individual differences in anlotinib-related adverse reactions.

Effects of CYP2C19, CYP2C9 and CYP3A4 gene polymorphisms on plasma voriconazole levels in Chinese pediatric patients.

Voriconazole is the most commonly used antifungal agent in clinical application. Previous studies suggested that voriconazole was extensively metabolized by CYP450 enzyme system, including CYP2C19, CYP2C9 and CYP3A4, which contributed to the individual variability of the pharmacokinetic process of voriconazole. This study aimed to investigate the effects of CYP2C19, CYP2C9 and CYP3A4 gene polymorphisms on plasma voriconazole concentrations in Chinese pediatric patients. This study prospectively evaluated pediatric patients administrating voriconazole for the treatment or prophylaxis of invasive fungal infections from October 2018 to July 2020. Seven single-nucleotide polymorphisms in CYP2C19 (CYP2C19*2, CYP2C19*3, and CYP2C19*17), CYP2C9 (CYP2C9*3, CYP2C9*13) and CYP3A4 (CYP3A4*22, rs4646437) were detected by real-time fluorescent PCR with TaqMan probes. The voriconazole trough plasma concentration was determined by UPLC-MS/MS. A total of 68 pediatric patients were enrolled in this study. Our results showed that voriconazole plasma concentrations of patients with CYP2C19*2 or CYP2C19*3 allele were significantly higher than that with wild-type carriers (P < 0.0001, P = 0.004, respectively). However, CYP2C9*3 and CYP3A4 rs4646437 were not significantly associated with voriconazole plasma levels. The CYP2C19*17, CYP2C9*13 and CYP3A4*22 alleles were not observed in our study. Additionally, multiple linear regression analysis indicated that CYP2C19*2 and CYP2C19*3 alleles remained predictors of voriconazole plasma concentration (r2 = 0.428; P < 0.0001). For CYP2C19 metabolizer phenotype, trough concentration of voriconazole was significantly lower in NM group compared with IM (P < 0.0001) and PM (P = 0.004) groups. Voriconazole plasma levels in pediatric patients are mainly affected by CYP2C19 gene polymorphisms.

Impact of CYP2C19, CYP3A4, ABCB1, and FMO3 genotypes on plasma voriconazole in Thai patients with invasive fungal infections.

Voriconazole is the first‐line antifungal choice in the treatment of invasive fungal infections (IFIs). Single nucleotide polymorphisms (SNPs) in drug‐metabolizing and transporter genes may affect voriconazole pharmacokinetics. This study aimed to determine the frequency of the CYP2C19 rs4244285, rs4986893, rs72552267, and rs12248560, CYP3A4 rs4646437, ABCB1 rs1045642, and FMO3 rs2266782 alleles and determine the association between these genetic variants and voriconazole concentrations in Thai patients with invasive fungal infections. The study comprised 177 Thai patients with IFIs in whom seven SNPs in CYP2C19, CYP3A4, ABCB1, and FMO3 were genotyped using TaqMan real‐time polymerase chain reaction (RT‐PCR) 5´ nuclease assays, and voriconazole plasma concentrations were measured by high‐performance liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). Of the 177 patients included, 31 were <12 years and 146 were ≥12 years. The CYP2C19 allele frequencies were 0.29 for *2, 0.060 for *3, 0.003 for *6, and 0.008 for *17. The allele frequency of CYP3A4 (rs4646437) was 0.26, ABCB1 (rs1045642) was 0.36, and FMO3 (rs2266782) was 0.16. The median voriconazole dose/weight was significantly lower in patients aged ≥12 years when compared to the patients aged <12 years (P < .001). Patients aged <12 years with CYP2C19*1/*2 exhibited significantly higher median voriconazole plasma concentrations than those with the CYP2C19*1/*1 (P = .038). However, there were no significant differences in median voriconazole plasma concentrations among the CYP2C19 genotypes in the patients aged ≥12 years. There was a lack of association observed among the CYP3A4, ABCB1, and FMO3 genotypes on the plasma voriconazole concentrations in both groups of patients. Our findings indicate that voriconazole plasma concentrations are affected by the CYP2C19*2 allele in patients aged <12 years but not in patients aged ≥12 years.

Randomised multicentre clinical trial to evaluate voriconazole pre-emptive genotyping strategy in patients with risk of aspergillosis: vorigenipharm study protocol.

IntroductionInvasive aspergillosis is the most important cause of morbidity and mortality in patients with haematological diseases. At present, voriconazole is the first-line treatment for invasive fungal disease. The pharmacokinetic interindividual variability of voriconazole depends on genetic factors. CYP450 is involved in 70%–75% of total metabolism of voriconazole, mainly CYP3A4 and CYP2C19, with the remaining 25%–30% of metabolism conducted by monooxygenase flavins. CYP2C19 single nucleotide polymorphisms could explain 50%–55% of variability in voriconazole metabolism.Materials and methodsThe main objective is to compare efficiency of pre-emptive voriconazole genotyping with routine practice. The primary outcome is serum voriconazole on the fifth day within the therapeutic range. The secondary outcome is the combined variables of therapeutic failure and adverse events within 90 days of first administration, associated with voriconazole. A total of 146 patients at risk of invasive aspergillosis who will potentially receive voriconazole will be recruited, and CYP2C19 will be genotyped. If the patient ultimately receives voriconazole, they will be randomised (1:1 experimental/control). In the experimental arm, patients will receive a dose according to a pharmacogenetic algorithm, including CYP2C19 genotype and clinical and demographic information. In the control arm, patients will receive a dose according to clinical practice guidelines. In addition, a Spanish National Healthcare System (NHS) point-of-view cost-effectiveness evaluation will be performed. Direct cost calculations for each arm will be performed.ConclusionThis trial will provide information about the viability and cost-effectiveness of the implementation of a pre-emptive voriconazole genotyping strategy in the Spanish NHS.Ethics and disseminationA Spanish version of this protocol has been evaluated and approved by the La Paz University Hospital Ethics Committee and the Spanish Agency of Medicines and Medical Devices. Trial results will be submitted for publication in an open peer-reviewed medical speciality-specific publication.Trial registration numberEudra-CT: 2019-000376-41 and NCT04238884; Pre-results.

No association between CYP2C19 genetic polymorphism with treatment remission to antidepressant venlafaxine in Han Chinese population.

Major depressive disorder (MDD) is a global mental health problem. As a serotonin-noradrenaline reuptake inhibitor (SNRI), the antidepressant venlafaxine is used to alleviate MDD clinically. Recent research has shown that Cytochrome P450 (CYP) enzymes affect venlafaxine efficacy by mediating its metabolism. The present study investigates genetic polymorphisms of cytochrome P450 family 2 subfamily C member 19 (CYP2C19) are associated with remission after venlafaxine treatment for MDD. A total of 175 Han Chinese patients with depression were recruited to accept a 6-week treatment with venlafaxine. Three single-nucleotide polymorphisms of CYP2C19 were selected from dbSNP and previous literature to compare the allele and genotype frequencies between patients in remission and nonremission. Seventeen items Hamilton Depression Scale (17-HAMD) was used to access the outcomes of patients' depressive symptoms through the study. Our results denied the role of CYP2C19 polymorphisms for remission after venlafaxine treatment in MDD patients. CYP2C19 genetic polymorphism may not have association with SNRI venlafaxine treatment remission in the Han Chinese population.

CYP2C19 Metabolizer Status Does Not Influence the Safety or Efficacy of Pentamidine

<h3>Background</h3> <i>Pneumocystis jirovecii</i> (PJP) infections are a significant cause of morbidity and mortality in recipients of hematopoietic cell transplantations (HCT), and PJP prophylaxis is a standard of care. The gold standard for PJP prophylaxis is sulfamethoxazole and trimethoprim (SMX/TMP), however, SMX/TMP is known to cause neutropenia so it is often avoided in the pre- and early post-HCT period. Alternatively, pentamidine can be administered in the early post HCT period without concern of marrow suppression. Pentamidine is a substrate of the CYP2C19, a CYP450 enzyme with known polymorphisms affecting metabolizer activity. A previous adult study demonstrated that patients with at least one ‘no function' allele were at an increased risk of serious adverse effects including death. We sought to determine the influence of CYP2C19 metabolizer status on the safety and efficacy of pentamidine in pediatric HCT population. <h3>Methods</h3> A retrospective chart review was conducted on all patients undergoing HCT at Cincinnati Children's Hospital between June 2013 and September 2018. Analysis of single nucleotide polymorphisms of CYP2C19 (*2, *3, *4, *5, *6, *7, *8, *17) were performed on a Taqman™ Low Density Array as part of routine clinical care. Incidence of breakthrough PJP infections, pentamidine discontinuation due to adverse effects as well as patient and transplant demographic information were collected. <h3>Results</h3> A total of 319 patients received pentamidine and had CYP2C19 genotyping perfomed during the study period.There were 8 poor metabolizers (two no function alleles), 101 intermediate metabolizers (one no function allele and one normal or increased function allele), 128 normal metabolizers (two normal function alleles) and 82 ultrarapid metabolizers (two increased function alleles or one normal allele and one increased function allele). There was no difference in the number of patients who discontinued therapy due to adverse events among metabolizer status groups, nor was there a difference in the number of breakthrough PJP infections (Table 1). <h3>Conclusions</h3> Our study demonstrates that, in contrast to the adult study, it is safe and efficacious to administer pentamidine in pediatric HCT patients regardless of CYP2C19 metabolizer status.

Genetics and Extracellular Vesicles of Pediatrics Sleep Disordered Breathing and Epilepsy.

Sleep remains one of the least understood phenomena in biology, and sleep disturbances are one of the most common behavioral problems in childhood. The etiology of sleep disorders is complex and involves both genetic and environmental factors. Epilepsy is the most popular childhood neurological condition and is characterized by an enduring predisposition to generate epileptic seizures, and the neurobiological, cognitive, psychological, and social consequences of this condition. Sleep and epilepsy are interrelated, and the importance of sleep in epilepsy is less known. The state of sleep also influences whether a seizure will occur at a given time, and this differs considerably for various epilepsy syndromes. The development of epilepsy has been associated with single or multiple gene variants. The genetics of epilepsy is complex and disorders exhibit significant genetic heterogeneity and variability in the expressivity of seizures. Phenobarbital (PhB) is the most widely used antiepileptic drug. With its principal mechanism of action to prolong the opening time of the γ-aminobutyric acid (GABA)-A receptor-associated chloride channel, it enhances chloride anion influx into neurons, with subsequent hyperpolarization, thereby reducing excitability. Enzymes that metabolize pharmaceuticals including PhB are well known for having genetic polymorphisms that contribute to adverse drug–drug interactions. PhB metabolism is highly dependent upon the cytochrome P450 (CYP450) and genetic polymorphisms can lead to variability in active drug levels. The highly polymorphic CYP2C19 isozymes are responsible for metabolizing a large portion of routinely prescribed drugs and variants contribute significantly to adverse drug reactions and therapeutic failures. A limited number of CYP2C19 single nucleotide polymorphisms (SNPs) are involved in drug metabolism. Extracellular vesicles (EVs) are circular membrane fragments released from the endosomal compartment as exosomes are shed from the surfaces of the membranes of most cell types. Increasing evidence indicated that EVs play a pivotal role in cell-to-cell communication. Theses EVs may play an important role between sleep, epilepsy, and treatments. The discovery of exosomes provides potential strategies for the diagnosis and treatment of many diseases including neurocognitive deficit. The aim of this study is to better understand and provide further knowledge about the metabolism and interactions between phenobarbital and CYP2C19 polymorphisms in children with epilepsy, interplay between sleep, and EVs. Understanding this interplay between epilepsy and sleep is helpful in the optimal treatment of all patients with epileptic seizures. The use of genetics and extracellular vesicles as precision medicine for the diagnosis and treatment of children with sleep disorder will improve the prognosis and the quality of life in patients with epilepsy.

Influence of smoking on CYP2C19 genetic variants and clopidogrel efficacy in patients with minor stroke or transient ischaemic attack.

Studies suggest that smoking affects clopidogrel efficacy. However, whether it influences the association between CYP2C19 genetic variants and clopidogrel efficacy is not clear. In total, 2961 patients from the CHANCE trial were involved in this substudy and were successfully genotyped for two single-nucleotide polymorphisms of CYP2C19 (*2 and *3). The Cox proportional risk regression model was used to evaluate the interactions between CYP2C19*2 and CYP2C19*3 carrier status and clopidogrel efficacy stratified by smoking status. There were marginal significant interactions between CYP2C19*2 and CYP2C19*3 allele carrier status and antiplatelet treatment regimen for the risk of recurrent stroke and composite events (P=0.054, P=0.051, respectively) amongst smokers, but not in non-smokers. Amongst smokers, clopidogrel plus aspirin decreased the recurrence rate of stroke compared with aspirin alone in non-carriers (3.8% vs. 11.8%, hazard ratio 0.32, 95% confidence interval 0.15-0.65, P=0.002), but not in carriers. Similar results were also found for the recurrence rate of composite events in smokers. No significant difference was found for hemorrhage events in any group. Amongst patients with minor stroke or transient ischaemic attack, marginal significant interactions between CYP2C19*2 and CYP2C19*3 allele carrier status and clopidogrel efficacy were found in smokers but not in non-smokers. Amongst smokers, clopidogrel plus aspirin might decrease the recurrence rate of stroke in non-carriers of *2 and *3 alleles of CYP2C19 compared with aspirin alone. However, caution should be taken to interpret our findings in view of several limitations in our study.

Abstract WP517: Influence of Smoking on CYP2C19 Genetic Variants and Clopidogrel Efficacy in Patients with Minor Stroke or TIA

Background and Purpose: Whether smoking has an effect on the association between CYP2C19 genetic variants and clopidogrel efficacy is not clear. This study was aimed to estimate the influence of smoking on the association between CYP2C19 genetic variants and clopidogrel efficacy among patients with minor stroke and TIA. Methods: In total of 2961 patients from the CHANCE trial were involved in this substudy and successfully genotyped for both two single-nucleotide polymorphisms of CYP2C19 (*2 and *3). Current smokers were defined as those who smoked at least five cigarettes per day in the last month. The primary clinical efficacy outcome of this study was a new stroke. Cox proportional risk regression model was used to evaluate the interactions between CYP2C19 loss-of-function allele (*2 and *3) carrier status and clopidogrel efficacy stratified by smoking status. Results: There were marginal significant interactions between CYP2C19 loss-of-function carrier status and antiplatelet treatment regimen for the risk of recurrent stroke and composite events (p = 0.054, p = 0.051, respectively) among smokers, but not in non-smokers. Among smokers, clopidogrel plus aspirin decreased the recurrence rate of stroke compared with aspirin alone in noncarriers (3.8% vs 11.8%, hazard ratio [HR], 0.32; 95% confidence interval [CI], 0.15-0.65, p = 0.002), but not in carriers (8.1% vs 10.8%, HR, 0.73; 95% CI, 0.46-1.17, p = 0.19). Similar results were also found for the recurrence rate of composite events in smokers. No significant difference was found for hemorrhage events in all groups. Conclusions: Among patients with minor stroke or TIA, marginal significant interactions were found between CYP2C19 loss-of-function carrier status and clopidogrel efficacy in smokers, but not in non-smokers. It seemed that among smokers, clopidogrel plus aspirin might decrease the recurrence rate of stroke in noncarriers of CYP2C19 loss-of-function allele compared with aspirin alone.

Influence of Proton Pump Inhibitors on Mycophenolic Acid Pharmacokinetics in Patients With Renal Transplantation and the Relationship With Cytochrome 2C19 Gene Polymorphism

BackgroundMost patients have serious digestive complications after renal transplantation. Therefore, it is important to protect gastrointestinal function to improve the survival rate of transplant patients. Proton pump inhibitors (PPIs) such as lansoprazole and rabeprazole are widely administered to renal transplant patients with mycophenolic acid (MPA) in the perioperative period. PPIs are metabolized by cytochrome (CYP) 2C19 enzymes. Mycophenolate sodium (MYF) and mycophenolate mofetil (MMF) have been used in immunosuppression. Clinically relevant drug-drug interactions have been described between immunosuppressive drugs. In the present study, we investigated the drug interaction between MPA and lansoparazole or rabeprazole and the impact of CYP2C19 polymorphisms on these drug interactions after renal transplantation. Materials and MethodsA total of 125 renal transplant patients taking MPA derivatives between 2012 and 2016 were included in this study. The 125 patients were divided into 6 groups: MMF/tacrolimus/steroid together with lansoprazole or rabeprazole; MYF/tacrolimus/steroid together with lansoprazole or rabeprazole and without PPI. The single nucleotide polymorphisms of CYP2C19 were determined by the polymerase chain reaction-restriction fragment length polymorphism. Plasma concentrations of MPA were measured by cloned enzyme donor immunoassay. Clinical parameters such as incidence of delayed graft function and acute rejection, the rate of change of serum creatinine, toxicity, and gastrointestinal adverse effects were analyzed retrospectively. ResultsThe mean concentrations of MPA in the MYF group were higher than those in the MMF group. The mean dose-adjusted blood concentration of MPA coadministered with lansoprazole was lower than that of MPA with rabeprazole or without PPI in MMF and MYF groups (P < .05). In patients with the CYP2C19*2/*2 genotype, the mean concentrations of MMF with lansoprazole were significantly lower than those with rabeprazole with MMF or without PPI (P < .05). Gastrointestinal side effects were significantly higher in MMF with lansoprazole group than in MYF with lansoprazole group (P < .05). However, no differences were found according to genotype distribution in all groups (P > .05). ConclusionPolymorphisms in CYP2C19 are related to the metabolic oxidation of drugs to varying degrees. Both genetic and clinical factors in pharmacokinetics may help to make further progress toward individualized therapy to yield maximum efficacy with minimal side effects.

Effects of CYP2C19 Genetic Polymorphisms on PK/PD Responses of Omeprazole in Korean Healthy Volunteers.

The aim of this study was to examine the effects of CYP2C19*2 and *3 genetic polymorphisms on omeprazole pharmacokinetic (PK) and pharmacodynamic (PD) responses. Twenty-four healthy Korean volunteers were enrolled and given 20 mg omeprazole orally once daily for 8 days. The genotypes of CYP2C19 single nucleotide polymorphisms (SNPs) (*2, *3, and *17) were screened. The plasma concentrations of omeprazole, omeprazole sulfone, and 5-hydroxy (5-OH) omeprazole were determined by liquid chromatography with tandem mass spectrometry (LC-MS/MS). The noncompartmental method was used for the determination of PK parameters. Change of mean pH and proportion (%) of time of gastric pH above 4.0 were estimated. The poor metabolizer (PM) group had the lowest metabolic ratio and exhibited the highest area under the curve (AUC) for omeprazole among the CYP2C19 phenotype groups. The PM group showed the greatest change of mean pH and the highest % time of gastric pH above 4.0. The relationship between AUC of omeprazole and % time of gastric pH above 4.0 was confirmed. The study demonstrates that CYP2C19*2 and *3 influence the PKs and PDs of omeprazole in Korean healthy volunteers. Clinical trial registry at the U.S. National Institutes of Health (https://clinicaltrials.gov), number NCT02299687.

Rapid and ultra-rapid metabolizers with CYP2C19*17 polymorphism do not respond to standard therapy with proton pump inhibitors

Introduction and objectivePolymorphisms in genes encoding drug metabolizing enzymes may lead to varied enzyme activity and inter-individual variability in drug efficacy and/or toxicity. Since CYP2C19 and CYP3A4 genes code for enzymes involved in metabolizing wide variety of drugs including proton pump inhibitors, we sought to identify polymorphisms in these genes in order to study their impact on drug metabolism in subjects. MethodsDNA was isolated from healthy individuals including tribals and genotyped for 11 single nucleotide polymorphisms in CYP2C19 and 6 polymorphisms in CYP3A4. Individuals were categorized into different phenotypes based on their drug metabolizing genotype. Volunteers from each group were administered proton pump inhibitors (Esomeprazole, Pantoprazole; 40mg/day) for 5days followed by pharmacokinetic studies and measurement of intra-gastric pH. ResultsOf the 17 polymorphisms studied, only CYP2C19*2,*3,*17 and CYP3A4*1B polymorphisms were observed. In comparison to urban individuals, a significantly (p=0.0003) higher number of poor metabolizers were noted in the tribal individuals. Pantoprazole was found to be most effective in poor metabolizers in terms of area under the curve and Tmax. No significant difference was observed in the intra-gastric pH at baseline and day 6 in rapid and ultra-rapid metabolizers. ConclusionOur study has demonstrated that 19.7% of our subjects are carriers of the CYP2C19*17 allele who did not respond to the standard dose of proton pump inhibitors. Genetic screening to identify subjects with variant alleles would thus be useful for personalization of therapy with proton pump inhibitors.

Association between genetic polymorphisms of cytochrome P450 2C19 and the risk of cerebral ischemic stroke in Chinese.

BackgroundCytochrome P450 (CYP) 2C19 is a very important drug metabolizing enzyme. Although the single nucleotide polymorphisms (SNPs) of CYP2C19 G681A and G636A have been suggested that they may increase the incidence of cardiovascular events, the relationship between SNPs in CYP2C19 and cerebral ischemic stroke (CIS) are unclear. The aim of this study was to investigate the correlation between the distribution of G681A and G636A polymorphisms in CYP2C19 gene and the risk of CIS in Chinese.MethodsThe peripheral blood DNA was extracted from 299 patients with CIS and 295 healthy controls. The genotyping was conducted using the polymerase chain reaction-restriction fragment length polymorphism. The sampled sequencing was applied to verify the correctness of genotyping results. Both the genotype and allele distributions were compared in patients with CIS and healthy controls.ResultsThe frequencies of CYP2C19 681AA (11.7% vs. 2.7%; P = 0.000), 636AA (4.0% vs. 0.7%; P = 0.007), 636AG (7.0% vs. 2.2%; P = 0.038) genotype, CYP2C19 681A (30.9% vs. 20.8%; P = 0.000) and 636A (13.0% vs. 5.8%; P = 0.000) allele in the CIS group are significantly higher than those in the controls. The frequencies of CYP2C19 681AA (16.7% vs. 8.6%; P = 0.036), CYP2C19 636AA (7.0% vs. 2.2%; P = 0.038) genotype, CYP2C19 681A (36.4% vs. 27.6%; P = 0.023) and CYP2C19 636A (17.5% vs.10.3%; P = 0.010) allele in the recurrent stroke group are significantly higher than those in the first onset group. Multivariate logistic regression analysis of risk factors for cerebral ischemic stroke and recurrent stroke respectively suggests that the CYP2C19 681AA genotype may be an independent risk factor for CIS (OR = 6.179, 95% CI: 2.285 ~ 16.708; P = 0.000) and recurrent stroke (OR = 2.305, 95% CI: 1.121 ~ 4.743; P = 0.023).ConclusionsThe AA genotype and A allele of CYP2C19 G681A may be related to the occurrence and recurrence of cerebral ischemic stroke.

Functional Genetic Polymorphisms inCYP2C19Gene in Relation to Cardiac Side Effects and Treatment Dose in a Methadone Maintenance Cohort

Abstract Methadone maintenance therapy is an established treatment for heroin dependence. This study tested the influence of functional genetic polymorphisms in CYP2C19 gene encoding a CYP450 enzyme that contributes to methadone metabolism on treatment dose, plasma concentration, and side effects of methadone. Two single nucleotide polymorphisms (SNPs), rs4986893 (exon 4) and rs4244285 (exon 5), were selected and genotyped in 366 patients receiving methadone maintenance therapy in Taiwan. The steady-state plasma concentrations of both methadone and its EDDP metabolite enantiomers were measured. SNP rs4244285 allele was significantly associated with the corrected QT interval (QTc) change in the electrocardiogram (p=0.021), and the Treatment Emergent Symptom Scale (TESS) total score (p=0.021) in patients who continued using heroin, as demonstrated with a positive urine opiate test. Using the gene dose (GD) models where the CYP2C19 SNPs were clustered into poor (0 GD) versus intermediate (1 GD) and extensive (2 GD) metabolizers, we found that the extensive metabolizers required a higher dose of methadone (p=0.035), and showed a lower plasma R-methadone/methadone dose ratio (p=0.007) in urine opiate test negative patients, as well as a greater QTc change (p=0.008) and higher total scores of TESS (p=0.018) in urine opiate test positive patients, than poor metabolizers. These results in a large study sample from Taiwan suggest that the gene dose of CYP2C19 may potentially serve as an indicator for the plasma R-methadone/methadone dose ratio and cardiac side effect in patients receiving methadone maintenance therapy. Further studies of pharmacogenetic variation in methadone pharmacokinetics and pharmacodynamics are warranted in different world populations.

Proton Pump Inhibitors in Pediatrics

Proton pump inhibitors (PPIs) have become some of the most frequently prescribed medications for treatment of adults and children. Their effectiveness for treatment of peptic conditions in the pediatric population, including gastric ulcers, gastroesophageal reflux disease (GERD), and Helicobacter pylori infections has been established for children older than 1 year. Studies of the preverbal population of neonates and infants have identified doses that inhibit acid production, but the effectiveness of PPIs in the treatment of GERD has not been established except for the recent approval of esomeprazole treatment of erosive esophagitis in infants. Reasons that have been proposed for this are complex, ranging from GERD not occurring in this population to a lack of histologic identification of esophagitis related to GERD to questions about the validity of symptom scoring systems to identify esophagitis when it occurs in infants. The effectiveness of PPIs relates to their structures, which must undergo acidic activation within the parietal cell to allow the PPI to be ionized and form covalent disulfide bonds with cysteines of the H+–K+-adenosine triphosphatase (H+–K+-ATPase). Once the PPI binds to the proton pump, the pump is inactivated. Some PPIs, such as omeprazole and rabeprazole bind to cysteines that are exposed, and their binding can be reversed. After irreversible chemical inhibition of the proton pump, such as occurs with pantoprazole, the recovery of the protein of the pump has a half-life of around 50 h. Cytochrome P450 (CYP) 2C19 and to a lesser degree CYP3A4 clear the PPIs metabolically. These enzymes are immature at birth and reach adult levels of activity by 5–6 months after birth. This parallels studies of the maturation of CYP2C19 to adult levels by roughly the same age after birth. Specific single nucleotide polymorphisms of CYP2C19 reduce clearance proportionally and increase exposure and prolong proton pump inhibition. Prolonged treatment of pediatric patients with PPIs has not caused cancer or significant abnormalities.

Pharmacogenomics Study of Clopidogrel by RFLP based Genotyping of CYP2C19 in Cardiovascular Disease Patients in North-East Population of India

Introduction and Objective: Pharmacogenetics is a genetically determined variability in drug responses. The genes and their allelic variants which affect our response to drugs are the main routes in development of pharmacogenetics. Clopidogrel is an antiplatelet drug, used against athero-thrombotic events in cardiovascular patients. The objective of our study was to identify the CYP2C19 Single Nucleotide Polymorphisms, responsible for altering the metabolism of clopidogrel, at gene level. And to document the prevalence of CYP2C19 gene mutations in clopidogrel treated cardiovascular disease patients in Assam population, Guwahati Medical College & Hospital, in North- East India. Patients and Methods: We have studied 60 patients who received clopidogrel from Gauhati medical college and hospital Assam. Genomic DNA was extracted by using Hipura blood genomic DNA extracting mini preparation kit by following the manufacturer’s instructions.RFLP analysis was done by DNA amplification which was carried out by using set of primers and resulting ampicons of CYP2C19*2;CYP2C19*3 and CYP2C19*17 were subjected for Restriction digestion with SmaI, BamHI and Lwe0I respectively. Results: We found that CYP2C19*2 had allelic frequency of ~40% in Gauhati Medical College and Hospital, Assam, North East India. None of the samples were mutated with CYP2C19*3 andCYP2C19*17 allele. Other CYP2C19 variant alleles with reduced or absent enzymatic activity have been identified. Conclusion: We found that loss of functional allele CYP2C19*2 had higher carriage frequency; whereas, CYP2C19*3 and *17 alleles were not found in cardiovascular patients who were taking clopidogrel. Personalized therapy targeting patients who carry these genetic variants might help to improve the clinical outcome.

850P - Genetic Polymorphisms and Sunitinib Toxicity in Metastatic Renal-Cell Carcinoma

ABSTRACT Background Sunitinib (SU) is a multi-targeted receptor tyrosine kinase inhibitor that is approved for the treatment of renal cell carcinoma (RCC). However, several patients either do not respond to treatment or they experience significant toxicity. Our study aims to find genetic markers of toxicity and efficacy using a commercially available DNA microarray genotyping system. Methods 30 patients with newly diagnosed metastatic RCC, from January 2010 to May 2011, were evaluated prospectively at Hospital 12 de Octubre (Madrid, Spain). Pts received SU in repeated 6-wk cycles of 50 mg/day (4 wks on followed by 2 wks off treatment). A total of 92 of single nucleotide polymorphisms (SNPs) in 34 genes in the pharmacokinetic and pharmacodynamic pathways of drugs were analyzed using Drug inCode ® pharmacogenetic service. SNPs in candidate genes, together with clinical characteristics were tested univariately for association with the number of days of SU treatment until the first reduction of dose, PFS and OS. Results Complete analysis was possible in 25 pts. Pts with CYP1A2*1/*1. a low metabolizing genotype, had an increased risk of dose reductions due to toxicity compare to allele *1F (Median time to dose reduction: 2.33 months Vs NR; p Conclusions This preliminary analysis suggests that CYP1A2 and CYP2C19 SNPs may be associated with toxicity in patients with RCC treated with SU. As CYP1A2 and CYP2C19 activity could be affected by a variety of non-genetic factors, if confirmed, these results could lead to the necessity of controlling toxic and dietary habits of pts treated with SU. SNPs associated with toxicity and survival in this preliminary analysis are being validated in an independent cohort of RCC treated with SU (Garcia-Donas J, et al. Lancet Oncol 2011) and will be presented. Disclosure All authors have declared no conflicts of interest.

Prospective exploratory analysis of the association between genetic polymorphisms and sunitinib toxicity and efficacy in metastatic renal-cell carcinoma.

4620 Background: Sunitinib (SU) is a multi-targeted receptor tyrosine kinase inhibitor treatment that is approved for metastatic renal cell carcinoma (mRCC). However, several patients either do not respond to treatment or they experience significant toxicity.Our study aims to find genetic markers of toxicity and efficacy using a commercially available DNA microarray genotyping system. Methods: 30 patients with newly diagnosed mRCC, from January 2010 to May 2011, were evaluated prospectively at Hospital 12 de Octubre (Madrid, Spain). Pts received SU 50 mg/day, 4 wks on / 2 wks off treatment schedule. A total of 92 of single nucleotide polymorphisms (SNPs) in 34 genes in the pharmacokinetic and pharmacodynamic pathways of drugs were analyzed using Drug inCode pharmacogenetic service. SNPs in candidate genes, together with clinical characteristics were tested univariately for association with the number of days of SU treatment until the first reduction of dose, PFS and OS. Results: Complete analysis was possible in 25 pts. Pts with CYP1A2*1/*1.a low metabolizing genotype, had an increased risk of dose reductions due to toxicity compare to allele *1F (Median time to dose reduction : 2.33 months vs NR; p&lt;0.006). Pts with CYP2C19*1/*1 , wild type genotype, had an increased risk of dose reductions due to toxicity vs. other genotypes (Median time to dose reduction: 2.8 vs 9.73 months; p&lt;0.021). Catechol-O-methyltransferase (COMT) V158M polymorphisms, was associated with PFS and OS (Met/Met carriers median PFS and OS NR; Met/Val pts PFS= 15 months; OS=17.2 months and Val/Val pts PFS=3.3 months; OS= 4.4 months ; p=0.005 for PFS and p=0.003 for OS). Conclusions: This preliminary analysis suggests that CYP1A2 and CYP2C19 SNPs may be associated with toxicity in patients with RCC treated with SU. As CYP1A2 and CYP2C19 activity could be affected by a variety of non-genetic factors, if these is confirmed, it could lead to the necessity of controlling toxic and dietary habits of pts treated with SU. SNPs associated with toxicity and survival in this preliminary analysis are being validated in an independent cohort of RCC treated with SU (García-Donas J, et al. Lancet Oncol 2011).

TCT-725 Point-of-Care Genetic Testing of Eleven CYP2C19 Single Nucleotide Polymorphisms Identifies Extensive and Reduced Metabolizers of Clopidogrel With High Accuracy in Patients With Coronary Artery Disease

Point-of-Care Genetic Testing of Eleven CYP2C19 Single Nucleotide Polymorphisms Identifies Extensive and Reduced Metabolizers of Clopidogrel With High Accuracy in Patients With Coronary Artery Disease