Experience of a Strategy Including CYP2C19 Preemptive Genotyping Followed by Therapeutic Drug Monitoring of Voriconazole in Patients Undergoing Allogenic Hematopoietic Stem Cell Transplantation

Many factors have been described to contribute to voriconazole (VCZ) interpatient variability in plasma concentrations, especially CYP2C19 genetic variability. In 2014, Hicks et al. presented data describing the correlation between VCZ plasma concentrations and CYP2C19 diplotypes in immunocompromised pediatric patients and utilized pharmacokinetic modeling to extrapolate a more suitable VCZ dose for each CYP2C19 diplotype. In 2017, in our hospital, a clinical protocol was developed for individualization of VCZ in immunocompromised patients based on preemptive genotyping of CYP2C19 and dosing proposed by Hicks et al., Clinical Pharmacogenetics Implementation Consortium (CPIC) clinical guidelines, and routine therapeutic drug monitoring (TDM). We made a retrospective review of a cohort of 28 immunocompromised pediatric patients receiving VCZ according to our protocol. CYP2C19 gene molecular analysis was preemptively performed using PharmArray®. Plasma trough concentrations were measured by immunoassay analysis until target concentrations (1–5.5 μg/ml) were reached. Sixteen patients (57.14%) achieved VCZ trough target concentrations in the first measure after the initial dose based on PGx. This figure is similar to estimations made by Hicks et al. in their simulation (60%). Subdividing by phenotype, our genotyping and TDM-combined strategy allow us to achieve target concentrations during treatment/prophylaxis in 90% of the CYP2C19 Normal Metabolizers (NM)/Intermediate Metabolizers (IM) and 100% of the Rapid Metabolizers (RM) and Ultrarapid Metabolizers (UM) of our cohort. We recommended modifications of the initial dose in 29% (n = 8) of the patients. In RM ≥12 years old, an increase of the initial dose resulted in 50% of these patients achieving target concentrations in the first measure after initial dose adjustment based only on PGx information. Our experience highlights the need to improve VCZ dose predictions in children and the potential of preemptive genotyping and TDM to this aim. We are conducting a multicenter, randomized clinical trial in patients with risk of aspergillosis in order to evaluate the effectiveness and efficiency of VCZ individualization: VORIGENIPHARM (EudraCT: 2019-000376-41).

Tramadol-Related Deaths: Genetic Analysis in Relation to Metabolic Ratios

Tramadol (TR) metabolism is mainly dependent on the enzymatic activity of CYP2D6, which is controlled by genetic polymorphisms. Individuals are classified as poor (PMs), intermediate (IMs), extensive (EMs) or ultrarapid metabolizers (UMs) according to their genotype or phenotype. The determination of the metabolic phenotype for CYP2D6 can be of utmost importance in forensic and clinical contexts that involve TR intake. The present study aimed to describe CYP2D6 genetic variants in cases of TR-related deaths and to assess which metabolic ratio(s) (MRs) would allow to determine CYP2D6 phenotype without having to perform genetic analyses. Forty-eight postmortem blood samples were selected from TR-related death cases previously analyzed in a forensic context in North of France between 2013 and 2019. Initial available data included blood concentrations of TR and its two main metabolites (M1 & M2) determined using a LC-MS/MS method. TR metabolism was expressed as various MRs comprising TR/M1, TR/M2 and M2/M1. After DNA extraction, sequencing was used for genetic variant detections that affect CYP2D6 activity/expression. In the present study, the allelic variants with the higher frequency were CYP2D6*1 (68%), followed by *4 (21%). The most frequent phenotype is EMs (59.6%), followed by IMs (23.4%), PMs (12.8%) and UMs (6.4%). There was no significant correlation between each calculated MR and the genotypically predicted phenotypes, except for M2/M1 which appears related to the PM phenotype. The observed distribution of CYP2D6 genetic variants in this TR-related death population was similar to that found in the general Caucasian population. The present study displayed that the blood M2/M1 ratio could be the best-correlated TR MR to the PM phenotype, and could thus be used in forensic contexts where genetic analyses are not possible or poorly informative. For the other phenotypes, especially the UM phenotype, genetic analysis appears to be the only reliable method to predict the CYP2D6 phenotype.

CYP450 Genotype—Phenotype Concordance Using the Geneva Micrococktail in a Clinical Setting

Pharmacokinetic variability is a major source of differences in drug response and can be due to genetic variants and/or drug-drug interactions. Cytochromes P450 are among the most studied enzymes from a pharmacokinetic point of view. Their activity can be measured by phenotyping, and/or predicted by genotyping. Depending on the presence of drugs and/or diseases that can affect their in vivo activity, both approaches can be complementary. In 2014, the Geneva cocktail using dried blood spots was validated in healthy volunteers for CYP450 phenotyping. Since its clinical implementation, it has been used in approximately 500 patients in various clinical situations. Our study aims to report the concordance between CYP450 genotype and phenotype in real-life patients. The prospectively collected data from patients who were genotyped and/or phenotyped between January 2014 and December 2020 were reviewed. A total of 537 patients were genotyped and/or phenotyped for CYP450 during this period, and 241 underwent simultaneous genotyping and phenotyping allowing for genotype/phenotype concordance assessment. Genotyping correctly predicted poor metabolizer phenotypes for most CYPs isoenzymes studied, whereas agreement was more variable for intermediate, normal, and ultrarapid metabolizers. Discrepancies between the phenotype predicted on the basis of genotyping and the measured phenotype were not always explained by concurrent medication (phenotypic switch). Therefore genotyping and phenotyping tests are complementary approaches when aiming to individualize drug therapy. In the 537 patients, the majority of clinical situations were observed with analgesic/anesthetic drugs (n = 187), followed by antidepressants (n = 153), antineoplastics (n = 97), and immunosuppressants (n = 93). Inefficacy (or low drug levels) and adverse drug reaction (or high drug levels) were the main reasons for testing. Genotype and/or phenotype results explained or at least contributed to the clinical event in 44% of cases.

Genetic Polymorphisms Associated With the Pharmacokinetics, Pharmacodynamics and Adverse Effects of Olanzapine, Aripiprazole and Risperidone

Olanzapine, aripiprazole and risperidone are atypical antipsychotics or neuroleptics widely used for schizophrenia treatment. They induce various adverse drug reactions depending on their mechanisms of action: metabolic effects, such as weight gain and alterations of glucose and lipid metabolism; hyperprolactinemia and extrapyramidal effects, such as tremor, akathisia, dystonia, anxiety and distress. In this review, we listed polymorphisms associated with individual response variability to olanzapine, aripiprazole and risperidone. Olanzapine is mainly metabolized by cytochrome P450 enzymes, CYP1A2 and CYP2D6, whereas aripiprazole and risperidone metabolism is mainly mediated by CYP2D6 and CYP3A4. Polymorphisms in these genes and other enzymes and transporters, such as enzymes from the uridine 5'-diphospho-glucuronosyltransferase (UGT) family and ATP-binding cassette sub-family B member 1 (ABCB1), are associated to differences in pharmacokinetics. The three antipsychotics act on dopamine and serotonin receptors, among others, and several studies found associations between polymorphisms in these genes and variations in the incidence of adverse effects and in the response to the drug. Since olanzapine is metabolized by CYP1A2, a lower starting dose should be considered in patients treated with fluvoxamine or other CYP1A2 inhibitors. Regarding aripiprazole, a reduced dose should be administered in CYP2D6 poor metabolizers (PMs). Additionally, a reduction to a quarter of the normal dose is recommended if the patient is treated with concomitant CYP3A4 inhibitors. Risperidone dosage should be reduced for CYP2D6 PMs and titrated for CYPD6 ultrarapid metabolizers (UMs). Moreover, risperidone dose should be evaluated when a CYP2D6, CYP3A4 or ABCB1 inhibitor is administered concomitantly.

Prevalence of CYP2C19 polymorphism in Bogotá, Colombia: The first report of allele *17

Introduction Proton pump inhibitors (PPIs) are a group of drugs that are essential for the treatment of acid-related disorders, such as gastroesophageal reflux (GERD), dyspepsia, gastric ulcers and Helicobacter pylori (H. pylori) infection. PPIs such as omeprazole, esomeprazole, pantoprazole and lansoprazole are metabolized by the CYP2C19 enzyme, which is encoded by a polymorphic gene. Four polymorphisms have an impact on the speed of PPI metabolism: CYP2C19*1/*1 (extensive metabolizers), CYP2C19*2/*2 (intermediate metabolizers), CYP2C19*3/*3 (poor metabolizers) and CYP2C19*17/*17 (ultrarapid metabolizers). Extensive and ultrarapid metabolizers inactivate PPIs quickly, which consequently causes low plasma concentrations of PPIs, while intermediate or poor metabolizers have higher plasma concentrations of PPIs and, therefore, PPIs have greater therapeutic efficacy in individuals with these polymorphisms. Objective To determine the frequency of genetic polymorphisms of the CPY2C19 enzyme in Bogotá, Colombia. Methods This observational study was conducted in Bogotá between 2012 and 2015 and was part of a clinical trial (ID: NCT03650543). It included 239 subjects with dyspepsia, H. pylori infection, or GERD symptoms. CYP2C19 genotyping was performed on gastric biopsy samples. Polymorphisms *1, *2, and *3 were analyzed by real-time PCR (Roche®), and PCR-RFLP was used to determine the presence of polymorphism *17. Results The distribution of different types of PPI metabolizers was as follows: extensive (70.7%), ultrarapid (12.9%), intermediate (8.8%) and poor (0.8%). Conclusion The population studied consisted mainly of extensive and ultrarapid PPI metabolizers. These findings show that it is necessary to increase PPI doses in this group of subjects or to use PPIs that are not metabolized by CYP2C19 (rabeprazole). This is the first Colombian work to identify ultrarapid metabolizers.

METABOLOMICS REVEALS FIVE ENDOGENOUS BIOMARKERS IN HUMAN URINE AND PLASMA TO PREDICT CYP2D6 ACTIVITY

Background and Purpose: Individualized assessment of the activity of cytochrome P450 2D6 (CYP2D6), a highly variable drug-metabolizing enzyme, is performed through phenotyping during which a probe drug is administered to measure the enzyme’s activity. In order to avoid any iatrogenic harm (allergic drug reaction, dosing error) related to the probe drug, the development of non-invasive tools for real-time phenotyping of CYP2D6 could significantly contribute to the expansion of precision medicine in clinical practice. This study focuses on the identification of endogenous markers of the CYP2D6 enzyme in human biofluids using a liquid chromatography (LC)-high-resolution mass spectrometry (HRMS)-based metabolomics approach. Experimental Approach: Data from a control session were compared to data from an inhibition session. Before the latter, healthy volunteers (extensive and ultrarapid metabolizers) received a daily dose of paroxetine 20 mg over seven days. CYP2D6 genotyping and phenotyping, using single oral dose of dextromethorphan 5 mg, were also performed in all participants. Key Results: In CYP2D6 extensive and ultrarapid metabolizers (n = 37), mean relative intensities of five features were significantly reduced during the inhibition session compared to the control session (fold changes ≤ 0.67, FDR-adjusted P < 0.0001). Furthermore, mean relative intensities of these candidates were significantly higher in the CYP2D6 extensive-ultrarapid metabolizer group (n = 37) compared to the poor metabolizer group (n = 6) (fold changes ≤ 0.67, P < 0.0001). Conclusion and Implications: The applied untargeted metabolomics strategy was able to identify five CYP2D6 endogenous metabolites, a promising discovery for non-invasive phenotyping and personalised medicine.

Implementation of CYP2D6 copy-number imputation panel and frequency of key pharmacogenetic variants in Finnish individuals with a psychotic disorder

PurposeWe constructed a CYP2D6 copy-number imputation panel by combining copy-number information to GWAS chip data. In addition, we report frequencies of key pharmacogenetic variants in individuals with a psychotic disorder from the genetically bottle-necked population of Finland.MethodsWe combined GWAS chip and CYP2D6 copy-number variation (CNV) data from the Breast Cancer Pain Genetics study (BrePainGen) to construct an imputation panel (N=902) for CYP2D6 CNV. The resulting data set was used as a CYP2D6 CNV imputation panel in 9,262 non-related individuals passing genotype data quality control procedures. The panel performance was evaluated by genotyping the CNV from a subset (N=297) of SUPER-Finland participants.ResultsCYP2D6 CNV was imputed correctly in 272 (92%) individuals. Sensitivity and specificity for detecting a duplication were 0.986 and 0.946, respectively. Sensitivity and specificity for detecting a deletion using imputation were 0.886 and 0.966, respectively. Based on imputation, the frequency of a CYP2D6 duplication and deletion in the whole SUPER-Finland sample with 9,262 non-related individuals passing quality control were 8.5% and 2.7%, respectively. We confirm the higher frequency of CYP2D6 ultrarapid metabolizers in Finland compared with non-Finnish Europeans. Additionally, we confirm a 21-fold enrichment of the UGT1A1 decreased function variant rs4148323 (also known as 211G>A, G71R or UGT1A1*6) in Finland compared with non-Finnish Europeans. Similarly, the NUDT15 variant rs116855232 was highly enriched in Finland.ConclusionOur results demonstrate that imputation of CYP2D6 CNV is possible. The methodology is not accurate enough to be used in clinical decision making, but it enables studying CYP2D6 in large biobanks with genome-wide data. In addition, it allows for researchers to recontact patients with certain pharmacogenetic variations through biobanks. We show that bottle-necked populations may have pharmacogenetically important variants with allele frequencies very different from the main ancestral group. Future studies should assess whether these differences are large enough to cause clinically significant changes in trial results across different ancestral groups.

High prevalence of CYP2D6 ultrarapid metabolizers in a mestizo Colombian population in relation to Hispanic mestizo populations

Background: Interethnic differences in CYP2D6 allele frequency have been demonstrated across Latin–American countries. Only one previous study describing CYP2D6 genotypes in Colombian population has been performed. Thus, this study aimed to evaluate the CYP2D6 genetic variability in a mestizo Colombian population, as well as the similarities and differences concerning other Hispanic mestizo (HM) populations. Methodology: Two hundred and twelve unrelated healthy Colombian subjects were studied, in which different CYP2D6 polymorphisms were analyzed by extra long-PCR and real-time PCR. Results & discussion: A high percentage of ultrarapid metabolizers (18.4%) was found, representing the highest frequency calculated within the HM populations studied. However, the percentage of poor metabolizers (4.7%) was similar to those previously reported in HM populations.

Description of Pharmacogenomic Testing Among Patients Admitted to the Intensive Care Unit After Cardiovascular Surgery

Background: Pharmacogenomic (PGx) testing has the potential to provide information on specific drug-metabolizing enzymes that may lead to an absence, reduction, or increase in medication effect in patients. There is a paucity of prospective studies examining PGx testing in the intensive care unit (ICU) setting. Research Aims: To (1) obtain a PGx panel in a sample of cardiovascular (CV) surgical patients with a planned ICU stay and identify phenotypes, and (2) identify PGx variants that may inform treatment regimens and may warrant prescribing adjustments. Design and Methods: Descriptive, single cohort cross-sectional design. Adult (≥18 years) CV patients with an anticipated postoperative ICU stay were enrolled from a large Midwestern tertiary academic medical center. Eligible patients provided informed consent at the time of their CV clinic appointment; PGx testing was then ordered. Pharmacogenomic testing consisted of the Focused Pharmacogenomics panel which included 10 genes and 55 medications. Results: Of the 272 patients screened, 100 (68% male) patients completed PGx testing (mean age 66.2 ± 9.6 years, mean Acute Physiology, Age and Chronic Health Evaluation III score 76.1 ± standard deviation). Pharmacogenomic results were available in the medical record within a median of 52.4 hours (interquartile range: 33.4-80.3). Pharmacogenomic testing results identified 5 CYP2C19 poor metabolizers, 26 CYP2C19 rapid metabolizers, 5 CYP2C19 ultrarapid metabolizers, 6 CYP2D6 poor metabolizers, 5 CYP2D6 poor to intermediate metabolizers, and 2 CYP2D6 rapid metabolizers identified. Overall, 98% of patients had actionable or potentially actionable PGx results, including 82% for warfarin, 65% for propafenone, 65% for tramadol, 46% for oxycodone, 45% for metoprolol, 33% for clopidogrel, 32% for proton pump inhibitors, 25% for statins, and 12% for haloperidol. Conclusions: A significant portion of patients had identified genetic variants that may warrant changes in medication management during and after CV-ICU stay. It remains to be seen if PGx testing leads to improvements in ICU patient outcomes.

Studying of cyp2c19*2, *3 and *17 polymorphism in Vietnamese patients with coronary artery disease

Coronary artery disease is the most common type of cardiovascular disease, due to the accumulation of atherosclerotic plaque inside the arterial wall which leads to block blood supply to the heart muscle. A number of clinical trials have demonstrated that Clopidogrel is able to inhibit platelet aggregation in patients with acute coronary syndromes, reduce mortality and cardiovascular events. However, the antiplatelet effectiveness of Clopidogrel significantly depends on CYP2C19 genotypes. Therefore, the aim of this study was to identify the CYP2C19*2, *3 and allele frequencies in Vietnamese coronary artery patients by using PCR-RFLP method. Total genomic DNA were extracted from peripheral blood of 96 patients diagnosed with coronary artery disease. Thereafter, single nucleotide polymorphism sites in the CYP2C19 gene were identified by PCR with specific primers. The amplified products were then digested by restriction enzymes SmaI, BamHI, and MnlI, respectively. The results showed that the proportion of heterozygous individuals for CYP2C19*2 (c. 681G>A, rs4244285), CYP2C19*3 (c. 636G>A, rs4986893), and CYP2C19*17 (g. -3402C>T, rs11188072) accounted for 39.58%, 6.25%, and 2.08%, respectively. Among 96 subjects, 41.67% of patients were predicted for intermediate metabolic phenotype CYP2C19*1/*2 (37.50%) and CYP2C19*1/*3 (4.17%). Approximately 10.42% of total patients represented poor metabolizers in which 8.34% had two copies of the same allele *2/*2 and 2.08% had *2/*3 genotype. Particularly, two individuals (2.08%) detected with CYP2C19*1/*17 genotype were able to increase CYP2C19 activity (ultrarapid metabolizers). The results of this study generate a foundation for introducing individualized antiplatelet therapy in Vietnam based on genetic testing.