CYP2C19 Polymorphisms and Clinical Outcomes Following Percutaneous Coronary Intervention (PCI) in the Million Veterans Program

Background

CYP2C19 loss-of-function (LOF) alleles decrease the antiplatelet effect of clopidogrel following percutaneous coronary intervention (PCI) in patients presenting with acute coronary syndrome (ACS). The impact of genotype in stable ischemic heart disease (SIHD) is unclear.

Objectives

Determine the association of CYP2C19 genotype with major adverse cardiac events (MACE) after PCI for ACS or SIHD.

Methods

Million Veterans Program (MVP) participants age <65 years with a PCI documented in the VA Clinical Assessment, Reporting and Tracking (CART) Program between 1/1/2009 to 9/30/2017, treated with clopidogrel were included. Time to MACE defined as the composite of all-cause death, stroke or myocardial infarction within 12 months following PCI.

Results

Among 4,461 Veterans (mean age 59.1 ± 5.1 years, 18% Black); 44% had ACS, 56% had SIHD and 29% carried a CYP2C19 LOF allele. 301 patients (6.7%) experienced MACE while being treated with clopidogrel, 155 (7.9%) in the ACS group and 146 (5.9%) in the SIHD group. Overall, MACE was not significantly different between LOF carriers vs. noncarriers (adjusted hazard ratio [HR] 1.18, confidence interval [95%CI] 0.97-1.45, p=0.096). Among patients presenting with ACS, MACE risk in LOF carriers versus non-carriers was numerically higher (HR 1.30, 95%CI 0.98-1.73, p=0.067). There was no difference in MACE risk in patients with SIHD (HR 1.09, 95%CI 0.82-1.44; p=0.565).

Conclusions

CYP2C19 LOF carriers presenting with ACS treated with clopidogrel following PCI experienced a numerically greater elevated risk of MACE events. CYP2C19 LOF genotype is not associated with MACE among patients presenting with SIHD.

Does the clopidogrel CYP2C19 genotype assay predict postprocedure stenosis in cerebral aneurysms treated with a flow diverter?

OBJECTIVE

Flow diverters have emerged as a popular modality for treating cerebral aneurysms but require dual antiplatelet therapy (DAPT) after placement. Clopidogrel is a common choice but is a prodrug that some patients may not convert into an active metabolite. The CYP2C19 genotype assay is used to predict activation speed; however, limited data exist showcasing whether this genotype accurately predicts postprocedure complications after flow diversion treatment of cerebral aneurysms. Therefore, the authors sought to characterize whether CYP2C19 genotype correlated with the development of postprocedure intimal hyperplasia (stenosis) after flow diverter placement.

METHODS

Medical records were reviewed for patients who underwent flow diverter treatment of cerebral aneurysm at a single academic institution between January 1, 2012, and May 31, 2020. Patient demographics and comorbidities were reviewed alongside CYP2C19 genotype assay, DAPT regimen, and postprocedure angiogram data. Stenosis was defined based on review of angiogram data by two independent physicians.

RESULTS

In this review of 120 unique cerebral aneurysms, 102 received DAPT with clopidogrel and 18 received DAPT with an alternative agent. Stenosis was present on 3-month follow-up angiogram for 35/102 (34.3%) aneurysms receiving DAPT with clopidogrel and in 11/18 (61.1%) aneurysms receiving an alternative DAPT regimen (p = 0.031). The CYP2C19 genotype did not correlate with postprocedure stenosis (p = 0.35).

CONCLUSIONS

Clopidogrel was a significantly more effective DAPT agent for preventing stenosis when compared to nonclopidogrel DAPT regimens. The clopidogrel CYP2C19 genotype did not predict postprocedure stenosis in this cohort of 120 cerebral aneurysms treated with a flow diverter.

CYP2C19 genotype and platelet aggregation test-guided dual antiplatelet therapy after off-pump coronary artery bypass grafting: A retrospective cohort study

Background

Dual antiplatelet therapy (DAPT) is recommended in patients undergoing off-pump coronary artery bypass graft surgery (OPCAB). Clopidogrel is less effective among patients with loss-of-function (LoF) of CYP2C19 alleles, while ticagrelor has direct effects on P2Y₁₂ receptor. Whether a CYP2C19 genotype plus platelet aggregation test (PAgT)-guided DAPT after CABG could improve clinical outcomes remain uncertain.

Materials and methods

From August 2019 to December 2020, 1,134 consecutive patients who underwent OPCAB received DAPT for 1 year after surgery in Ruijin Hospital, Shanghai Jiao Tong University School of Medicine. According to the actual treatment they received in real-world, 382 (33.7%) of them received a traditional DAPT: aspirin 100 mg qd + clopidogrel 75 mg qd, no matter the CYP2C19 genotype and response in platelet aggregation test (PAgT). The other 752 (66.3%) patients received an individual DAPT based on CYP2C19 genotype and PAgT: aspirin 100 mg qd + clopidogrel 75 mg qd if CYP2C19 was extensive metabolizer, or moderate metabolizer but normal response in PAgT; aspirin 100 mg qd + ticagrelor 90 mg bid if CYP2C19 was poor metabolizer, or moderate metabolizer but no or low response in PAgT. One-year follow-up was achieved for all patients. The primary outcome was major adverse cardiovascular events (MACE), a composite of cardiovascular death, myocardial infarction, and stroke. The safety outcome was thrombolysis in myocardial infarction (TIMI) criteria major bleeding.

Results

Compared with the traditional DAPT group, the risk of MACE in the individual DAPT group was significantly lower (5.5 vs. 9.2%, HR 0.583; 95% CI, 0.371-0.915; P = 0.019), mainly due to the decreased risk of MI (1.7 vs. 4.2%, HR 0.407; 95% CI, 0.196-0.846; P = 0.016). The risk of TIMI major bleeding events was similar between the two groups (5.3 vs. 6.0%, RR 0.883; 95% CI, 0.537-1.453; P = 0.626).

Conclusion

For patients who underwent OPCAB, individual DAPT (CYP2C19 genotype plus PAgT-guided strategy) was associated with a lower risk of MACE and a similar risk of major bleeding.

Population pharmacokinetics of omeprazole in obese and normal-weight adults

BACKGROUND

Obesity is related to many pathophysiological changes that may result in altered drug disposition. Omeprazole is the most common option utilized for acid-related disorders treatment; however, the pharmacokinetic (PK) and dosing recommendations for the obese patient population are lacking.

METHODS

Data from 40 healthy subjects with normal weights and data from 61 obese subjects were included. The subjects all received a single dose of 20 mg of omeprazole. Nonlinear mixed effects modeling were performed to characterize the effect of obesity on omeprazole PK.

RESULTS

A one-compartment model with twelve transit absorption compartments and linear elimination described the data best. A lower clearance was observed in the obese patient population than in the normal-weight subjects, which was opposite to the well-known allometric effect of body weight on drug clearance. Moreover, the CYP2C19 genotype was identified as a significant covariate for clearance.

CONCLUSION

Given the potential adverse events related to high exposure to proton pump inhibitors over time, obese patients may require a lower dose of omeprazole for long-term treatment. Further studies in obese individuals into other drugs metabolized by CYP2C19 are warranted, especially those with a narrow therapeutic window.

CLINICAL TRIAL REGISTRATION

www.chictr.org.cn identifier is ChiCTR2100046578; www.chinadrugtrials.org.cn identifier is CTR20190175.

Effect of major CYP2C19 genetic polymorphisms on Helicobacter pylori eradication based on different treatment regimens

Helicobacter pylori (H. pylori) infection is a global issue. Its eradication in affected individuals is important to prevent several further complications that may occur if left untreated. Proton pump inhibitors (PPIs) serve an important role in the eradication regimens of H. pylori. PPIs are metabolized primarily through the CYP2C19 enzyme in the liver. Inter-individual variation in the response to eradication treatment may partly be due to variations in the metabolism of PPIs. The aim of this study was to determine whether there was any association between CYP2C19 genetic polymorphisms and the response to eradication therapy amongst Jordanians infected with H. pylori receiving lansoprazole-based regimens. The present study was approved by the Institutional Review Board of The University of Jordan Hospital. A total of 141 patients infected with H. pylori were genotyped for the polymorphisms CYP2C19^*2 and CYP2C19^*17 using the PCR-restriction fragment length polymorphism assay method. Patients received lansoprazole-based triple or sequential therapy. The assessment of eradication was performed using either a H. pylori stool antigen test or from feedback from patients regarding their improvement. Eradication rates were 84.6% and 64.5% in the intermediate-metabolizer and extensive-metabolizer group, respectively. This difference was not statistically significant. Moreover, no significant association was found between the carriers of the CYP2C19^*17 polymorphism and the response to eradication therapy. These findings suggest that there was no significant association between the CYP2C19 genotype and the response to eradication therapy amongst Jordanians infected with H. pylori.

Utility of a pharmacogenetic-driven algorithm in guiding dual antiplatelet therapy for patients undergoing coronary drug-eluting stent implantation in China

PURPOSES

The POPular Risk Score (PRiS), a pharmacogenetic-driven algorithm consisting of CYP2C19 genotype, platelet reactivity, and clinical risk factors, is developed to evaluate ischemic risk and guide dual antiplatelet therapy (DAPT). This study aimed to evaluate the efficacy and safety of DAPT in accordance with the PRiS in patients undergoing drug-eluting stent (DES) implantation.

METHODS

A total of 1757 patients recruited in this cohort study were divided into four groups according to the PRiS and type of P2Y12 receptor inhibitor treatment at discharge. The primary endpoint was major adverse cardiovascular events (MACE, a composite of cardiovascular death, myocardial infarction, stroke, definite or probable stent thrombosis, and target vessel revascularization) during 1-year follow-up. The safety endpoints were defined by Bleeding Academic Research Consortium (BARC) criteria as major bleeding (BARC 3a, 3b, 3c, and 5) and clinically relevant bleeding (BARC 2, 3a, 3b, 3c, and 5).

RESULTS

Among 1046 patients with PRiS < 2 and 711 patients with PRiS ≥ 2, 34.2% and 38.3% of them were treated with ticagrelor, respectively. The PRiS ≥ 2 was an independent predictor for the 1-year incidence of MACE (HR(95%CI): 2.09 (1.37-3.20), p = 0.001). Multivariable Cox regression indicated that in the PRiS ≥ 2 group, ticagrelor was superior to clopidogrel in reducing the risk of MACE (HR(95%CI): 0.53 (0.29-0.98), p = 0.042), without increasing the bleeding risk. On the other hand, in the PRiS < 2 group, clopidogrel treatment was related to a remarkably lower rate of BARC class ≥ 2 bleeding (HR(95%CI): 0.39 (0.20-0.72), p = 0.003), but comparable incidences of MACE and BARC class ≥ 3 bleeding during 1-year follow-up. Similar associations between P2Y12 receptor inhibitors and 1-year endpoints in the PRiS < 2 and PRiS ≥ 2 group could also be identified in propensity score-weighted analysis and propensity score-matched analysis.

CONCLUSION

Tailored DAPT based on the PRiS could assist in improving the prognosis of patients undergoing DES implantation. Further randomized controlled trials are required to provide more evidence for PRiS-guided DAPT.

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.

Effect of CYP2C19 Genotype on Ischemic Outcomes During Oral P2Y12 Inhibitor Therapy: A Meta-Analysis

OBJECTIVES

The aim of this study was to examine the effect of CYP2C19 genotype on clinical outcomes in patients with coronary artery disease (CAD) who predominantly underwent percutaneous coronary intervention (PCI), comparing those treated with ticagrelor or prasugrel versus clopidogrel.

BACKGROUND

The effect of CYP2C19 genotype on treatment outcomes with ticagrelor or prasugrel compared with clopidogrel is unclear.

METHODS

Databases through February 19, 2020, were searched for studies reporting the effect of CYP2C19 genotype on ischemic outcomes during ticagrelor or prasugrel versus clopidogrel treatment. Study eligibility required outcomes reported for CYP2C19 genotype status and clopidogrel and alternative P2Y₁₂ inhibitors in patients with CAD with at least 50% undergoing PCI. The primary analysis consisted of randomized controlled trials (RCTs). A secondary analysis was conducted by adding non-RCTs to the primary analysis. The primary outcome was a composite of cardiovascular death, myocardial infarction, stroke, stent thrombosis, and severe recurrent ischemia. Meta-analysis was conducted to compare the 2 drug regimens and test interaction with CYP2C19 genotype.

RESULTS

Of 1,335 studies identified, 7 RCTs were included (15,949 patients, mean age 62 years; 77% had PCI, 98% had acute coronary syndromes). Statistical heterogeneity was minimal, and risk for bias was low. Ticagrelor and prasugrel compared with clopidogrel resulted in a significant reduction in ischemic events (relative risk: 0.70; 95% confidence interval: 0.59 to 0.83) in CYP2C19 loss-of-function carriers but not in noncarriers (relative risk: 1.0; 95% confidence interval: 0.80 to 1.25). The test of interaction on the basis of CYP2C19 genotype status was statistically significant (p = 0.013), suggesting that CYP2C19 genotype modified the effect. An additional 4 observational studies were found, and adding them to the analysis provided the same conclusions (p value of the test of interaction <0.001).

CONCLUSIONS

The effect of ticagrelor or prasugrel compared with clopidogrel in reducing ischemic events in patients with CAD who predominantly undergo PCI is based primarily on the presence of CYP2C19 loss-of-function carrier status. These results support genetic testing prior to prescribing P2Y₁₂ inhibitor therapy.

CYP2C19 genotype-directed P2Y12 inhibitor antiplatelet therapy normalizes risk for major adverse cardiovascular events after percutaneous coronary intervention

Objective

To study the use of CYP2C19 genotyping to guide P2Y₁₂ inhibitor selection to maximize efficacy, and attenuate risk in appropriate patients who underwent PCI for CAD.

Methods

We performed a retrospective analysis of 868 patients with CAD who received CYP2C19 genotyping after PCI and changed P2Y₁₂ inhibitor based on the results. Patients were divided into two groups based on clopidogrel metabolizer status. Group I: Intermediate (IM) and poor metabolizers (PM). Group II: Ultra-rapid (UM), rapid (RM) and normal metabolizers (NM). Each group was then categorized to one of two treatment arms guided by CYP2C19 genotype. Category 1: IM/PM started on clopidogrel, switched to ticagrelor or prasugrel; 2:IM/PM started on ticagrelor/prasugrel, continued these medications; 3: UM/RM/NM started on ticagrelor/prasugrel, switched to clopidogrel; 4: UM/RM/NM started on clopidogrel, continued clopidogrel. Death due to cardiac causes, bleeding events, non-fatal MI, target vessel revascularization (TVR), and MACE in all four categories were considered at 1, 6 and 12 months.

Results

We did not observe significant difference between phenotypes for MACE at 1 (p = 0.274), 6 (p = 0.387), and 12 months (p = 0.083). Death due to cardiac causes, MI, and bleeding events were not significant at 1, 6, and 12 months. There was no significant difference in TVR at 6 (p = 0.491), and 12 months (p = 0.423) except at 1 month (p = 0.012).

Conclusion

CYP2C19 genotype-based intervention can be implemented effectively and reliably to guide selection of P2Y₁₂ inhibitor to optimize patient quality and safety when appropriate in post PCI patients.

Cost-effectiveness of CYP2C19 LOF-guided antiplatelet therapy in Chinese patients with acute coronary syndrome

Aim: This study aimed to evaluate the cost-effectiveness of CYP2C19 loss-of-function(LOF) allele-guided antiplatelet therapy compared with the universal use of clopidogrel or ticagrelor among Chinese patients with acute coronary syndrome undergoing percutaneous coronary intervention. Methods: A two-part cost-effectiveness model comprising of a 1-year decision tree and a long-term Markov model was utilized to simulate outcomes of three treatment strategies: universal use of clopidogrel (75 mg daily) or universal use of ticagrelor 90 mg twice daily for all patients and CYP2C19 LOF-guided therapy (LOF allele carriers receiving ticagrelor, LOF allele noncarriers receiving clopidogrel). Model outcomes included quality-adjusted life years (QALYs) gained, direct medical costs and incremental cost-effectiveness ratios (ICERs). ICERs less than one-time gross domestic product per capita in China 59,660 yuan/QALY were considered cost-effective. Results: Base-case analysis showed 'universal ticagrelor use' was cost-effective for an ICER of 33,875 yuan per QALY gained compared with 'universal clopidogrel use' of which gained a 1.6932 QALYs at lowest life-long cost of 2450 yuan. CYP2C19 LOF-guided therapy had an effectiveness of 1.6975 QALYs at a cost of 2812 yuan, for an ICER of 84,118 yuan per QALY gained relative to 'universal clopidogrel use'. Sensitivity analysis demonstrated that base-case results were significantly affected by five factors: the risk ratio of 'non-fatal myocardial infarction', 'non-fatal stroke' and 'cardiovascular death' in ticagrelor versus clopidogrel and the annual costs of clopidogrel and ticagrelor. According to the results of Monte Carlo simulation, when willing to pay is about 32,000 yuan, patients willing to receive clopidogrel or ticagrelor are approximately equal. Conclusion: Optimal antiplatelet treatment is affected by lots of factors. The results of our study demonstrated that 'universal ticagrelor use' was cost-effective compared with 'universal clopidogrel use' for Chinese acute coronary syndrome patients with percutaneous coronary intervention.

A comparison of three platelet function tests in ischemic stroke patients with antiplatelet therapy

Predicting the effectiveness of antiplatelet drugs is critical to precision antiplatelet therapy. However, there is a lack of an acceptable method, although there are a variety of methods for detecting platelet function. In this study, we compared three major platelet function tests to assess their performance and found better methods for platelet function evaluation after aspirin or clopidogrel treatment in ischemic stroke patients by comparative study. A total of 249 ischemic stroke patients were enrolled who were treated with aspirin or clopidogrel or both. Three platelet function tests including light transmittance aggregometry (LTA), thromboelastography (TEG), platelet function analyzer (PFA) were performed as well as CYP2C19 genotype determination. Correlation analyses and kappa statistics were used. All three methods were effective in evaluating aspirin function. However, only LTA and TEG had good correlation and consistency (r = -0.37, kappa = 0.634). TEG-ADP was the least sensitive for clopidogrel, as the platelet inhibition ratio did not differ between the clopidogrel-user group and the control (P = 0.074), while LTA and PFA were sensitive (P ＜ 0.001). Correlations between platelet assays were poor for clopidogrel (the absolute value of r range from 0.13 to 0.35) and so was the agreement (Kappa from 0.232 to 0.314). LTA and PFA have a good correlation with CYP2C19 genotyping (P = 0.034 and 0.014). In conclusion, all three tests were able to evaluate aspirin effect, LTA-AA and TEG-AA had a good correlation. TEG perform badly for clopidogrel effect detection. The fair-to-modest agreement among assays indicated further study was indispensable.

Clarithromycin resistance and female gender affect Helicobacter pylori eradication failure in chronic gastritis

BACKGROUND/AIMS

The eradication rate of the first-line triple therapy (a proton pump inhibitor, clarithromycin, and amoxicillin) for Helicobacter pylori infection has gradually decreased in Korea. We evaluated whether clinical parameters, clarithromycin resistance, and CYP2C19 genotype can affect the eradication failure.

METHODS

A total of 203 patients with H. pylori-positive chronic gastritis were consecutively enrolled. They received clarithromycin-based triple therapy for 7 days. A clarithromycin resistance test was performed by detection of A2142G and A2143G point mutations in H. pylori 23S rRNA. The CYP2C19 genotype was examined for polymorphism G681A of exon 5 and G636A of exon 4 by polymerase chain reaction with restriction fragment length polymorphism. Eradication was assessed by a 13C-urea breath test 4 weeks after treatment.

RESULTS

Of 203 patients, 190 completed the study. The eradication rate was 64.0% according to intention-to-treat analysis and 68.4% by per-protocol analysis. CY-P2C19 genotypes were identified as follows: 75 poor metabolizers, 75 intermediate metabolizers, and 40 rapid metabolizers. Nonetheless, this polymorphism was not significantly associated with eradication failure (p = 0.682). Clarithromycin resistance was detected in 33/190 patients (17.4%), and their eradication rate was zero. Clarithromycin resistance (odds ratio [OR], 19.13; 95% confidence interval [CI], 9.35 to 35.09) and female gender (OR, 1.73; 95% CI, 1.15 to 4.25) were significantly associated with eradication failure. The other clinical parameters such as age, cigarette smoking, alcohol intake, the body mass index, hypertension, and diabetes were not significantly associated with eradication.

CONCLUSION

Clarithromycin resistance and female gender are factors affecting H. pylori eradication failure in patients with chronic gastritis.

CYP2C19 Genotype, CagA Genotype and Antibiotic Resistant Strain of Helicobacter pylori Infection

Background: H. pylori is a class I carcinogen and major cause of gastric cancer. Few previous studies reported relationship between H. pylori infection, CYP2C19 genotype and functional dyspepsia (FD) subtype. The aim of this study was to determine relationship between CYP2C19 genotype and FD subtype patients(host factor) with antibiotic resistant strains of H. pylori infection and CagA genotype(bacterial factor). Methods: FD patients who were investigated with gastroscopy at Thammasat University Hospital, Thailand during March 2017-November 2017 were enrolled. Two antral gastric biopsies were obtained for rapid urease test, E-test and cultures. CagA genotypes (CagA1a and CagA2a) were determined by PCR and CYP2C19 genotype was determined by PCR-RFLP. FD patients were categorized as epigastric pain syndrome(EPS) and postprandial distress syndrome (PDS). Results: 93 FD patients with H. pylori infection were enrolled (37 male, 56 female, mean age 54.5 years). There were 33 patients with EPS and 60 patients with PDS. CYP2C19 genotype revealed 55.9% rapid metabolizer (RM), 40.9% intermediate metabolizer (IM) and 3.2% poor metabolizer (PM) genotypes. Antibiotics susceptibility tests demonstrated 62.8% resistant to metronidazole, 12.9% resistant to clarithromycin and 27.1% resistant to fluoroquinolone. CagA 1a and CagA 2a were demonstrated in 6 patients(11.5%) and 46 patients(88.5%). CagA2a genotype was more prevalent in PDS than EPS patients (94.3%vs.76.5%; P =0.08) without significance. In intermediate metabolizer (IM), CagA2a genotype was significant higher in PDS than EPS(100% vs.25%; P=0.004). Conclusions: PDS, CYP2C19 RM genotype and CagA 2a gene of H. pylori infection were the predominant type of FD in Thailand. Metronidazole remain the most common antibiotic resistant strain of H. pylori infection in FD patients. PDS (host factor) was significantly related to CagA2a genotype (bacterial factors) only in patients with intermediate metabolizer. Appropriate dose of proton pump inhibitor (PPI) and correct regimens for H. pylori eradication in FD patients should be consider to improve clinical outcomes.

Combination of CYP2C19 genotype with non-genetic factors evoking phenoconversion improves phenotype prediction

BACKGROUND

CYP2C19 is an important drug-metabolizing enzyme, responsible for metabolism of approximately 10% of the drugs on the market. Large inter-individual differences exist in metabolic activities, which are primarily attributed to genetic polymorphism of CYP2C19 gene. Conflicting results have been published about the role of CYP2C19 polymorphisms in metabolism of CYP2C19 substrates and clinical outcomes; thus, we aimed to investigate CYP2C19 genotype-phenotype associations, and we sought to elicit potential causes of discrepancies in the genotype-based prediction by incorporating the liver donors' demographic data, drug administration events and pathological conditions.

METHODS

(S)-Mephenytoin was used to assess CYP2C19 activities in human liver microsomes derived from 114 Hungarian organ donors. CYP2C19 genotype was determined by SNP genotyping for CYP2C19*2, CYP2C19*3, CYP2C19*4 and CYP2C19*17 variants, and CYP2C19 mRNA levels were measured by qPCR method. Clinical data of the donors were considered in the genotype-based phenotype prediction.

RESULTS

CYP2C19 phenotype of 40% of the donors was well-predicted from the genotype data, whereas the phenotype of 13% was underestimated displaying higher activity, and of 47% was overestimated displaying lower activity than predicted from CYP2C19 genotype. Among the donors with overestimated phenotype, one was treated with CYP2C19 substrate/inhibitor, 9 were on amoxicillin-clavulanic acid therapy, 7 were chronic alcohol consumers and 9 had disease with inflammatory processes.

CONCLUSIONS

CYP2C19 genotype only partially determines the CYP2C19 phenotypic appearance; co-medication, diseases with inflammatory processes and aspecific factors, such as chronic alcohol consumption and amoxicillin-clavulanic acid therapy (or any drug therapy resulting in liver injury) seem to be potential phenotype-modifying factors.

Observational Study of Associations between Voriconazole Therapeutic Drug Monitoring, Toxicity, and Outcome in Liver Transplant Patients

The aim of this study was to investigate the variability of the voriconazole plasma level and its relationships with clinical outcomes and adverse events among liver transplant recipients to optimize the efficacy and safety of their treatment. Liver transplant recipients treated with voriconazole were included, and voriconazole trough levels were quantified by a validated high-performance liquid chromatography method. Cytochrome P450 genotypes for CYP2C19 were evaluated in allograft liver tissues. A total of 832 voriconazole trough levels from 104 patients were measured. Proven, probable, and possible invasive fungal infections were reported for 8/104 (7.7%), 42/104 (40.4%), and 54/104 (51.9%) patients, respectively. Receiver operating characteristic (ROC) curve analysis indicated that trough concentrations of ≥1.3 μg/ml minimized the incidence of treatment failure (95% confidence interval [CI], 0.68 to 0.91 μg/ml) (P < 0.001) and that those of <5.3 μg/ml minimized the incidence of any adverse events (95% CI, 0.83 to 0.97 μg/ml) (P < 0.001). Voriconazole trough levels were significantly higher for heterozygous extensive metabolizers, poor metabolizers, and individuals receiving coadministration with proton pump inhibitors. For ultrarapid metabolizers, oral administration of voriconazole, and concomitant use of glucocorticoids, voriconazole blood concentrations were significantly reduced. Furthermore, there was no statistically significant association of patient age, weight, or gender or coadministration of tacrolimus and cyclosporine with the voriconazole trough level. In conclusion, the results of our analysis indicate large inter- and intraindividual variabilities of voriconazole concentrations in liver transplant recipients. Voriconazole trough concentrations of ≥1.3 μg/ml and <5.3 μg/ml are optimal for treatment and for minimization of adverse events. Optimization of drug efficacy and safety requires the use of rational doses for voriconazole therapy.

CYP2C19 LOF and GOF-Guided Antiplatelet Therapy in Patients with Acute Coronary Syndrome: A Cost-Effectiveness Analysis

PURPOSE

This study aimed to examine the cost-effectiveness of CYP2C19 loss-of-function and gain-of-function allele guided (LOF/GOF-guided) antiplatelet therapy in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI).

METHODS

A life-long decision-analytic model was designed to simulate outcomes of three strategies: universal clopidogrel (75 mg daily), universal alternative P2Y₁₂ inhibitor (prasugrel 10 mg daily or ticagrelor 90 mg twice daily), and LOF/GOF-guided therapy (LOF/GOF allele carriers receiving alternative P2Y₁₂ inhibitor, wild-type patients receiving clopidogrel). Model outcomes included clinical event rates, quality-adjusted life-years (QALYs) gained and direct medical costs from perspective of US healthcare provider.

RESULTS

Base-case analysis found nonfatal myocardial infarction (5.62%) and stent thrombosis (1.2%) to be the lowest in universal alternative P2Y₁₂ inhibitor arm, whereas nonfatal stroke (0.72%), cardiovascular death (2.42%), and major bleeding (2.73%) were lowest in LOF/GOF-guided group. LOF/GOF-guided arm gained the highest QALYs (7.5301 QALYs) at lowest life-long cost (USD 76,450). One-way sensitivity analysis showed base-case results were subject to the hazard ratio of cardiovascular death in carriers versus non-carriers of LOF allele and hazard ratio of cardiovascular death in non-carriers of LOF allele versus general patients. In probabilistic sensitivity analysis of 10,000 Monte Carlo simulations, LOF/GOF-guided therapy, universal alternative P2Y₁₂ inhibitor, and universal clopidogrel were the preferred strategy (willingness-to-pay threshold = 50,000 USD/QALY) in 99.07%, 0.04%, and 0.89% of time, respectively.

CONCLUSIONS

Using both CYP2C19 GOF and LOF alleles to select antiplatelet therapy appears to be the preferred antiplatelet strategy over universal clopidogrel and universal alternative P2Y₁₂ inhibitor therapy for ACS patients with PCI.

Risk Factors for Voriconazole-Associated Hepatotoxicity in Patients in the Intensive Care Unit

STUDY OBJECTIVES

To determine the incidence of hepatotoxicity in critically ill patients who were treated with voriconazole and to identify potential risk factors for voriconazole-associated hepatotoxicity in these patients.

DESIGN

Single-center prospective observational study.

SETTING

Intensive care unit (ICU) in a university-affiliated hospital in Xi'an, China.

PATIENTS

Sixty-three adults, admitted to the ICU between January 2010 and July 2015, who had an ICU length of stay longer than 3 days, had received voriconazole treatment for at least 3 days, and had at least one trough voriconazole plasma concentration (VPC) measurement.

INTERVENTION

All patients received CYP2C19 genotyping and were evaluated for the development of hepatotoxicity by assessing liver function tests performed before, during, and after voriconazole therapy.

MEASUREMENTS AND MAIN RESULTS

Hepatotoxicity was classified according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) grade scores and was defined as a CTCAE grade score that had increased by at least 2 grade scores over the baseline score. Hepatotoxicity occurred in 12 (19%) of the 63 patients. Characteristics of the patients who developed hepatotoxicity were compared with those of the patients who did not develop hepatotoxicity by univariate and multivariate Cox regression analyses. In the univariate analysis, Acute Physiology and Chronic Health Evaluation II score, invasive fungal infection classification, CYP2C19 genotype, and trough VPC were identified as the variables, and they were subsequently combined in the multivariate regression analysis. Multivariate Cox regression analysis revealed that hepatotoxicity was independently associated with trough VPC (hazard ratio 1.76, p<0.001). The relationships between trough VPCs and probability of hepatotoxicity were explored by using logistic regression analysis, and a target VPC upper limit of 4 mg/L was identified. The Kaplan-Meier method for the cumulative incidence of hepatotoxicity showed a significant difference between patients with trough VPCs of 4 mg/L or higher and those with VPCs lower than 4 mg/L (p<0.001).

CONCLUSION

Trough VPC was an independent risk factor associated with a greater risk of developing hepatotoxicity in critically ill patients, with a potentially toxic target trough concentration threshold of 4 mg/L identified for this complex population.

A study on the impact of CYP2C19 genotype and platelet reactivity assay on patients undergoing PCI

BACKGROUND

A thorough understanding of the patient's genotype and their functional response to a medication is necessary for improving event free survival. Several outcome studies support this view particularly if the patient is to be started on clopidogrel due to the prevalence of clopidogrel resistance. Such guided therapy has reduced the incidence of Major Adverse Cardiac Events (MACE) after stent implantation.

METHODS

Between August 2013 and August 2014, 200 patients with coronary artery disease undergoing percutaneous coronary intervention (PCI) were prescribed any one of the anti-platelet medications such as clopidogrel, prasugrel or ticagrelor and offered testing to detect CYP2C19 gene mutations along with a platelet reactivity assay (PRA). Intended outcome was modification of anti-platelet therapy defined as either dose escalation of clopidogrel or replacement of clopidogrel with prasugrel or ticagrelor for the patients in clopidogrel arm, and replacement of ticagrelor or prasugrel with clopidogrel if those patients were non-carrier of mutant genes and also if they demonstrated bleeding tendencies in the ticagrelor and prasugrel arms.

CONCLUSION

Clopidogrel resistance was observed to be 16.5% in our study population. PRA was useful in monitoring the efficacy of thienopyridines. By having this test, one can be safely maintained on clopidogrel in non-carriers, or with increased dose of clopidogrel in intermediate metabolizers or with newer drugs such as ticagrelor or prasugrel in poor metabolizers. Patients on ticagrelor and prasugrel identified as non-carriers of gene mutations for clopidogrel metabolism could be offered clopidogrel resulting in economic benefits to the patients. Patients at high risk of bleeding were also identified by the PRA.