CYP2D6 Genotype Research Articles

CYP2D6 gene polymorphic markers role in determining the optimal treatment tactics for portal hypertension in patients with liver cirrhosis

To study the polymorphic markers CYP2D6*4 (G1846A, rs3892097), CYP2D6*6 (T1707del, rs5030655), CYP2D6*10 (C100T, rs1065852), CYP2D6*41 (G2988A, rs28371725) and CYP2D6*3 (A2549del, rs4986774) role in treatment optimization of portal hypertension with propranolol in patients with liver cirrhosis (LC). The study included 60 patients with LC who received propranolol therapy at a daily dose of 30 mg for 14 days. The efficacy of treatment was assessed by ultrasonography measuring the linear blood flow velocity of portal vein. Genotyping of CYP2D6*4, CYP2D6*6, CYP2D6*10, CYP2D6*41 and CYP2D6*3 was carried out by real-time polymerase chain reaction. Evaluation of the CYP2D6 activity was carried out by determining the ratio of pinoline and its metabolite concentration in morning urine using high performance liquid chromatography with mass spectrometry. Positive hemodynamics in the form of any increase in the mean linear blood flow velocity of the portal vein compared to baseline was observed in 41 patients. Portal vein mean linear blood flow rate increased from 10.43.9 to 14.74.3 cm/s (p0.001). Of these, 29 patients showed an increase in this indicator by 20% from the initial one with a dynamic of 5.5 cm/s (p0.001). The regression analysis constructed by us revealed the presence of a statistically significant effect of the CYP2D6 gene polymorphic marker G1846A carriage on the propranolol therapeutic effect (p0.05). There was no statistically significant effect of polymorphic markers T1707del, C100T, G2988A, and A2549del of the CYP2D6 gene (p0.05). No convincing reliable dependence of CYP2D6 activity on the severity of LC was revealed (p0.05). An association was found between CYP2D6 gene polymorphic marker G1846A carriage and the hemodynamic effect of propranolol in patients with LC of the Russian population. There is a more significant positive dynamics of manifestations of portal hypertension on the background of propranolol therapy in carriers of the homozygous GG CYP2D6*4 genotype, in contrast to patients with the heterozygous GA genotype. Based on the results of the study, an algorithm has been developed for personalizing the treatment of patients with LC with nonselective b-adrenergic blockers using the method of CYP2D6 genotyping. Carriage of polymorphic markers T1707del, C100T, G2988A and A2549del gene CYP2D6 does not affect the effectiveness of propranolol therapy in patients with LC.

Abstract P1-07-08: Endoxifen predicts early recurrence in breast cancer: A Brazilian prospective study

Abstract Tamoxifen is widely used in adjuvant therapy for breast cancer patients, but up to one-third of patients recur within 15 years after surgery even with its regular use. Low plasma levels of (Z)-endoxifen, the most active tamoxifen metabolite, have been studied as a possible predictor of treatment failure. Here, we evaluated plasma (Z)-endoxifen as a predictor of response to adjuvant treatment in breast cancer patients. Methods: One hundred forty nine patients were selected from a prospective cohort of consecutive newly diagnosed breast cancer patients recruited at a national referral center for treatment of cancer in Curitiba, Southern Brazil. Inclusion criteria were breast cancer women on stage I - III, positive hormone receptor tumors, operable, undergoing or not (neo)adjuvant chemotherapy, and signed for adjuvant tamoxifen for at least five years. At diagnosis, peripheral blood samples were collected for CYP2D6 genotyping for *1 *2, *3, *4, *5, *6, *7, *8, *9, *10, *17, *29 and *41 and subsequent metabolic activity scores according to phenotypes assigned for each allele (poor metabolizer PM; intermediate, IM; extensive, EM and ultrarapid metabolizer, UM). After the tamoxifen initiation, patients were evaluated at months 3, 6, and 12 for adherence and drug interactions, and plasma (Z)-endoxifen quantification. They were followed from April 2014 to April 2019. The study's primary objective was to evaluate whether (Z)-endoxifen plasma levels predict early recurrence in patients on adjuvant tamoxifen. The secondary aim was to evaluate an association between (Z)-endoxifen levels and clinical and phenotypic CYP2D6 metabolism variables. A Cox model estimated hazard ratios (HR) comparing recurrence free survival (RFS) according to (Z)-endoxifen plasma levels. The survival was compared using the Kaplan-Meier method and the log-rank test. Results: The median follow-up period was 52.3 months and at that point, there were 20 recurrences of 149 patients. At 3 months there were no cases of low adherence to tamoxifen. The (Z)-endoxifen levels were established by quartiles, with the first lower quartile being used as a cutoff (14.72nM). High (Z)-endoxifen levels at 3 months (>14.72nM) were detected in 75.8% (n = 113) of cases and low levels (≤14.72nM) in 24.2% (n = 36). There was no statistically significant difference between the groups with low or high (Z)-endoxifen levels regarding clinical and pathological variables, but there was a higher CYP2D6 PM/IM frequency in the low (Z)-endoxifen levels group (p<0.001). High (Z)-endoxifen levels were associated with lower RFS compared to low (Z)-endoxifen levels (HR 2.5, 95% CI 1.00-6.22, p=0.041). Low (Z)-endoxifen levels increased the recurrence risk even when adjusted for staging and molecular subtypes (HR 2.55, 95% CI 1.00-6.48, p<0.001) or staging and CYP2D6 phenotype (UM/EM vs IM/PM; HR 4.38, 95% CI 1.66-11.59, p=0.003), or prior chemotherapy exposure (HR 2.65, 95% CI 1.06-6.61, p=0.036). Conclusion: This is the first Brazilian prospective trial evaluating the association of plasma (Z)-endoxifen levels, with the clinical outcome in breast cancer women treated with adjuvant tamoxifen, controlled by predictable confounding factors of plasma (Z)-endoxifen levels, such as tamoxifen adherence, and drug interaction with CYP2D6 inhibitors. In our study, a low plasma level of (Z)-endoxifen (≤ 14.72nM) after 3 months of tamoxifen treatment was a predictor of early recurrence in patients under adjuvant tamoxifen (p=0.041). A longer follow-up and a larger cohort may be needed to confirm the (Z)-endoxifen cutoff value that is a predictor of long-term recurrence. Citation Format: Thais Almeida, Werner Schroth, Jeanine Marie Nardin, Thomas Mürdter, Solane Picolotto, Reiner Hoppe, Jenifer Primon Kogin, Elisa Daniele Gaio, Angela Dasenbrock, Raquel Cristina Skrsypcsak, Lucia Noronha, Hiltrud Brauch, José Claudio Casali-da-Rocha. Endoxifen predicts early recurrence in breast cancer: A Brazilian prospective study [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-07-08.

The Mechanism, Clinical Efficacy, Safety, and Dosage Regimen of Atomoxetine for ADHD Therapy in Children: A Narrative Review.

Atomoxetine, a selective norepinephrine (NE) reuptake inhibitor, was approved for attention deficit/hyperactivity disorder (ADHD) treatment in children, adolescents and adults. We searched the database PubMed/MEDLINE (2000 to October 1, 2021). Only publications in English were considered. Atomoxetine inhibits the presynaptic norepinephrine transporter (NET), preventing the reuptake of NE throughout the brain along with inhibiting the reuptake of dopamine in specific brain regions such as the prefrontal cortex (PFC). The novel mechanism of atomoxetine also includes several new brain imaging studies and animal model studies. It is mainly metabolized by the highly polymorphic drug metabolizing enzyme cytochrome P450 2D6 (CYP2D6). Atomoxetine is effective and generally well tolerated. ADHD is often accompanied by multiple comorbidities. A series of studies have been published suggesting that atomoxetine is effective in the treatment of ADHD symptoms for children with various types of comorbidity. In some cases, it is possible that atomoxetine may have a positive influence on the symptoms of comorbidities. Atomoxetine can be administered either as a single daily dose or split into two evenly divided doses, and has a negligible risk of abuse or misuse. The latest guideline updated that clinical dose selection of atomoxetine was recommended based on both CYP2D6 genotype and the peak concentration. To have a more comprehensive understanding of atomoxetine, this review sets the focus on the mechanism, clinical efficacy and dosage regimen in detail, and also touches on those studies regarding adverse reactions of atomoxetine.

A pharmacogenomic investigation of the cardiac safety profile of ondansetron in children and pregnant women

BackgroundOndansetron is a highly effective antiemetic for the treatment of nausea and vomiting. However, this medication has also been associated with QT prolongation. Pharmacogenomic information on therapeutic response to ondansetron exists, but no investigation has been performed on genetic factors that influence the cardiac safety of this medication. MethodsThree patient groups receiving ondansetron were recruited and followed prospectively (pediatric post-surgical patients n = 101; pediatric oncology patients n = 98; pregnant women n = 62). Electrocardiograms were conducted at baseline, and 5- and 30-min post-ondansetron administration, to determine the effect of ondansetron treatment on QT interval. Pharmacogenomic associations were assessed via analyses of comprehensive CYP2D6 genotyping and genome-wide association study data. ResultsIn the entire cohort, 62 patients (24.1%) met the criteria for prolonged QT, with 1.2% of the cohort exhibiting unsafe QT prolongation. The most significant shift from baseline occurred at five minutes post-ondansetron administration (P = 9.8 × 10−4). CYP2D6 activity score was not associated with prolonged QT. Genome-wide analyses identified novel associations with a missense variant in TLR3 (rs3775291; P = 2.00 × 10−7) and a variant linked to the expression of SLC36A1 (rs34124313; P = 1.97 × 10−7). ConclusionsThis study has provided insight into the genomic basis of ondansetron-induced cardiac changes and has emphasized the importance of genes that have been implicated in serotonin-related traits. These biologically-relevant findings represent the first step towards understanding this adverse event with the overall goal to improve the safety of this commonly used antiemetic medication.

The interplay between pharmacogenetics, concomitant drugs and blood levels of amitriptyline and its main metabolites.

Background: The research considers the impact of genotype-inferred variability on blood levels of amitriptyline and its main metabolites, as may be moderated by phenocopying. Patients & methods:CYP2D6 and CYP2C19 genotypes, and serum concentrations of amitriptyline, nortriptyline and hydroxymetabolites, were determined in 33 outpatients. Co-medications were reviewed to identify CYP inhibition risk. Results: CYP2C19 metabolizer status explained interpatient variation in nortriptyline to amitriptyline concentration ratios. The hydroxymetabolite to parent ratios increased with higher CYP2D6 activity scores and lower CYP2D6 inhibition risk. In patients at high CYP2D6 inhibition risk, the amitriptyline+ nortriptyline concentration was, on average, 52% above the higher end of expected ranges. Conclusion: Practical construal of pharmacogenetics and drug interactions tantamount to aberrant metabolism can facilitate patient-tailored use of the established drug.

Comparison of adverse drug reactions between tamoxifen and toremifene in breast cancer patients with different CYP2D6 genotypes: A propensity-score matched cohort study.

CYP2D6 gene polymorphism has a profound impact upon the effect of tamoxifen as adjuvant endocrine therapy in breast cancer. However, it had never been reported whether the adverse drug reactions vary by CYP2D6 metabolic status for patients treated with tamoxifen or toremifene. We conducted a retrospective study in breast cancer patients to investigate the impact of CYP2D6 metabolic status on liver dysfunction events, gynecological events and dyslipidemia events. According to CYP2D6*10 (100C → T) genotype, the enrolled patients were further categorized into four cohorts (extensive metabolizers taking tamoxifen [EM + TAM], extensive metabolizers taking toremifene [EM + TOR], intermediate metabolizers taking tamoxifen [IM + TAM], and intermediate metabolizers taking toremifene [IM + TOR]). A total of 192 patients were included in the study, with a median follow-up time of 26.2months. In EM + TAM cohort, the risks of liver dysfunction events (P=.004) and gynecological events (P=.004) were significantly higher compared to EM + TOR cohort. In IM + TAM cohort, the risks of liver dysfunction events (P=.14) and gynecological events (P=.99) were not significantly different from IM + TOR cohort. A significant decrease of total cholesterol was observed in EM + TAM cohort around 1year after taking tamoxifen (P < .001). Significant interactions between CYP2D6 metabolic status and endocrine agents were observed in terms of liver dysfunction events (P-interaction=.007) and gynecological events (P-interaction=.026). These findings suggested that CYP2D6 gene polymorphism played a significant role in predicting liver dysfunction, gynecological diseases and lipid metabolism changes among patients taking tamoxifen or toremifene.

Current research in pathophysiology of opioid-induced respiratory depression, neonatal opioid withdrawal syndrome, and neonatal antidepressant exposure syndrome

Respiratory depression (RD) is the primary cause of death due to opioids. Opioids bind to mu (µ)-opioid receptors (MORs) encoded by the MOR gene Oprm1, widely expressed in the central and peripheral nervous systems including centers that modulate breathing. Respiratory centers are located throughout the brainstem. Experiments with Oprm1-deleted knockout (KO) mice undertaken to determine which sites are necessary for the induction of opioid-induced respiratory depression (OIRD) showed that the pre-Bötzinger complex (preBötC) and the pontine Kölliker-Fuse nucleus (KF) contribute equally to OIRD but RD was not totally eliminated. Morphine showed a differential influence on preBötC and KF neurons – low doses attenuated RD following deletion of MORs from preBötC neurons and an increase in apneas after high doses whereas deletion of MORs from KF neurons but not the preBötC attenuated RD at both high and low doses. In other KO mice studies, morphine administration after deletion of Oprm1 from both the preBötC and the KF/PBN neurons, led to the conclusion that both respiratory centres contribute to OIRD but the preBötC predominates. MOR-mediated post-synaptic activation of GIRK potassium channels has been implicated as a cause of OIRD. A complementary mechanism in the preBötC involving KCNQ potassium channels independent of MOR signaling has been described. Recent experiments in rats showing that morphine depresses normal, but not gasping breathing, cast doubt on the belief that eupnea, sighs, and gasps, are under the control of preBötC neurons. Methadone, administered to alleviate symptoms of neonatal opioid withdrawal syndrome (NOWS), desensitized rats to OIRD. Protection lost between postnatal days 1 and 2 coincides with the preBötC becoming the dominant generator of respiratory rhythm. Neonatal antidepressant exposure syndrome (NADES) and serotonin toxicity (ST) show similarities including RD. Enzyme CYP2D6 involved in opioid detoxification is polymorphic. Individuals of different CYP2D6 genotype may show increased, decreased, or no enzyme activity, contributing to the variability of patient responses to different opioids and OIRD.

Pharmacogenetics: A Precision Medicine Approach to Combatting the Opioid Epidemic.

Ineffective pain control is the most commonly cited reason for misuse of prescription opioids and is influenced by genetics. In particular, the gene encoding the CYP2D6 enzyme, which metabolizes some of the most commonly prescribed opioids (e.g., tramadol, hydrocodone) to their more potent forms, is highly polymorphic and can lead to reduced concentrations of the active metabolites and decreased opioid effectiveness. Consideration of the CYP2D6 genotype may allow for predicting opioid response and identifying patients who are likely to respond well to lower potency opioids as well as those who may derive greater pain relief from non-opioid analgesics versus certain opioids. There is emerging evidence that a CYP2D6-guided approach to pain management improves pain control and reduces opioid consumption and thus may be a promising means for combating opioid misuse. Clinical practice guidelines are available for select opioids and other analgesics to support medication and dose selection based on pharmacogenetic data. This article describes the evidence supporting genotype-guided pain management as a means of improving pain control and reducing opioid misuse and clinical recommendations for genotype-guided analgesic prescribing. In addition, a "how to" guide using patient case examples is provided to demystify the process for implementing pharmacogenetics-guided pain management in order to optimize analgesia and minimize adverse effects. Optimizing pain management through genotype-guided approaches may ultimately provide safer and more effective therapy for pain control while decreasing the risk for opioid misuse.

Ontogeny of Pediatric Pharmacogenetics: Celebrating the Past and Vision for the Future.

Ontogeny of Pediatric Pharmacogenetics: Celebrating the Past and Vision for the Future.

Prediction of the CYP2D6 enzymatic activity based on investigating of the CYP2D6 genotypes around the vivax malaria patients in Yunnan Province, China

BackgroundIn recent years, the incidence rate of vivax malaria recurrence still had 3.1% in Yunnan Province population after eradication therapy using primaquine (PQ). In order to understand the specific failure reasons for preventing vivax malaria relapses, a preliminary exploration on the CYP2D6 enzyme activity was carried out in the vivax malaria patients in Yunnan Province population by analysing mutational polymorphism in the coding region of CYP2D6 gene.MethodsBlood samples were collected from vivax malaria patients with suspected relapse (SR) and non-relapsed (NR) malaria in Yunnan Province. The DNA fragments containing 9 exons regions of human CYP2D6 gene were amplified by performing PCR and sequenced. The sequencing results were aligned by using DNAStar 11.0 to obtain the coding DNA sequence (CDS) of CYP2D6 gene. DnaSP 6.11.01 software was used to identify mutant polymorphisms and haplotypes of the CDS chain. The waterfall function of GenVisR package in R was utilized to visualize the mutational landscape. The alleles of CYP2D6 gene were identified according to the criteria prescribed by Human Cytochrome P450 (CYP) Allele Nomenclature Committee Database and the CYP2D6 enzyme activity was predicted based on diploid genotype.ResultsA total of 320 maternal CDS chains, including 63 from SR group and 257 from NR group, were obtained. Twelve mutant loci, including c.31 (rs769259), c.100 (rs1065852), c.271 (rs28371703), c.281 (rs28371704), c.294 (rs28371705), c.297 (rs200269944), c.336 (rs1081003), c.408 (rs1058164), c.505 (rs5030865), c.801 (rs28371718), c.886 (rs16947), and c.1,457 (rs1135840) were observed on the 640 CDS chains (including 320 maternal and 320 paternal chains). The high-frequency mutation at rs1135840 (0.703) and low-frequency mutation, such as rs28371703, were detected only in the SR group. The frequency of mutant rs1058164 and rs1135840 were significantly increased in the SR group ({x}^{2}= 4.468, 5.889, P < 0.05), as opposed to the NR group. Of the 23 haplotypes (from Hap_1 to Hap_23), the nomenclatures of 11 allelic forms could be found: Hap_3 was non-mutant, Hap_2 accounted for the highest frequency (36.9%, 236/640), and Hap_9 had the most complex sequence structure, containing 7 loci mutations. Allele *10 was the most frequent among these genotypes (0.423). Among the allele *10 standard named genotypes, *1/*10, *1/*1 and *2/*10 were significantly more frequent in the NR group ({x}^{2}= 3.911, P < 0.05) and all showed uncompromised enzyme activity; the impaired genotype *10/*39 was more frequent in the SR group ({x}^{2}= 10.050, P < 0.05), and genotype *4/*4was detected only in the SR group.ConclusionIn the patients receiving PQ dosage in Yunnan Province population, both rs1135840 single nucleotide polymorphism and *10 allele form was common in the CYP2D6 gene. Low-frequency mutation sites, such as rs28371703, were only presented in patients with vivax malaria relapse.

Methodology for clinical genotyping of CYP2D6 and CYP2C19

Many antidepressants, atomoxetine, and several antipsychotics are metabolized by the cytochrome P450 enzymes CYP2D6 and CYP2C19, and guidelines for prescribers based on genetic variants exist. Although some laboratories offer such testing, there is no consensus regarding validated methodology for clinical genotyping of CYP2D6 and CYP2C19. The aim of this paper was to cross-validate multiple technologies for genotyping CYP2D6 and CYP2C19 against each other, and to contribute to feasibility for clinical implementation by providing an enhanced range of assay options, customizable automated translation of data into haplotypes, and a workflow algorithm. AmpliChip CYP450 and some TaqMan single nucleotide variant (SNV) and copy number variant (CNV) data in the Genome-based therapeutic drugs for depression (GENDEP) study were used to select 95 samples (out of 853) to represent as broad a range of CYP2D6 and CYP2C19 genotypes as possible. These 95 included a larger range of CYP2D6 hybrid configurations than have previously been reported using inter-technology data. Genotyping techniques employed were: further TaqMan CNV and SNV assays, xTAGv3 Luminex CYP2D6 and CYP2C19, PharmacoScan, the Ion AmpliSeq Pharmacogenomics Panel, and, for samples with CYP2D6 hybrid configurations, long-range polymerase chain reactions (L-PCRs) with Sanger sequencing and Luminex. Agena MassARRAY was also used for CYP2C19. This study has led to the development of a broader range of TaqMan SNV assays, haplotype phasing methodology with TaqMan adaptable for other technologies, a multiplex genotyping method for efficient identification of some hybrid haplotypes, a customizable automated translation of SNV and CNV data into haplotypes, and a clinical workflow algorithm.

Evaluating the Risk of Breast Cancer Recurrence and Metastasis After Adjuvant Tamoxifen Therapy by Integrating Polymorphisms in Cytochrome P450 Genes and Clinicopathological Characteristics.

Tamoxifen (TAM) is the most commonly used adjuvant endocrine drug for hormone receptor-positive (HR+) breast cancer patients. However, how to accurately evaluate the risk of breast cancer recurrence and metastasis after adjuvant TAM therapy is still a major concern. In recent years, many studies have shown that the clinical outcomes of TAM-treated breast cancer patients are influenced by the activity of some cytochrome P450 (CYP) enzymes that catalyze the formation of active TAM metabolites like endoxifen and 4-hydroxytamoxifen. In this study, we aimed to first develop and validate an algorithm combining polymorphisms in CYP genes and clinicopathological signatures to identify a subpopulation of breast cancer patients who might benefit most from TAM adjuvant therapy and meanwhile evaluate major risk factors related to TAM resistance. Specifically, a total of 256 patients with invasive breast cancer who received adjuvant endocrine therapy were selected. The genotypes at 10 loci from three TAM metabolism-related CYP genes were detected by time-of-flight mass spectrometry and multiplex long PCR. Combining the 10 loci with nine clinicopathological characteristics, we obtained 19 important features whose association with cancer recurrence was assessed by importance score via random forests. After that, a logistic regression model was trained to calculate TAM risk-of-recurrence score (TAM RORs), which is adopted to assess a patient’s risk of recurrence after TAM treatment. The sensitivity and specificity of the model in an independent test cohort were 86.67% and 64.56%, respectively. This study showed that breast cancer patients with high TAM RORs were less sensitive to TAM treatment and manifested more invasive characteristics, whereas those with low TAM RORs were highly sensitive to TAM treatment, and their conditions were stable during the follow-up period. There were some risk factors that had a significant effect on the efficacy of TAM. They were tissue classification (tumor Grade < 2 vs. Grade ≥ 2, p = 2.2e−16), the number of lymph node metastases (Node-Negative vs. Node < 4, p = 5.3e−07; Node < 4 vs. Node ≥ 4, p = 0.003; Node-Negative vs. Node ≥ 4, p = 7.2e−15), and the expression levels of estrogen receptor (ER) and progesterone receptor (PR) (ER < 50% vs. ER ≥ 50%, p = 1.3e−12; PR < 50% vs. PR ≥ 50%, p = 2.6e−08). The really remarkable thing is that different genotypes of CYP2D6*10(C188T) show significant differences in prediction function (CYP2D6*10 CC vs. TT, p < 0.019; CYP2D6*10 CT vs. TT, p < 0.037). There are more than 50% Chinese who have CYP2D6*10 mutation. So the genotype of CYP2D6*10(C188T) should be tested before TAM therapy.

The benefit of diagnostic whole genome sequencing in schizophrenia and other psychotic disorders.

Schizophrenia has a multifactorial etiology, involving a polygenic architecture. The potential benefit of whole genome sequencing (WGS) in schizophrenia and other psychotic disorders is not well studied. We investigated the yield of clinical WGS analysis in 251 families with a proband diagnosed with schizophrenia (N = 190), schizoaffective disorder (N = 49), or other conditions involving psychosis (N = 48). Participants were recruited in Israel and USA, mainly of Jewish, Arab, and other European ancestries. Trio (parents and proband) WGS was performed for 228 families (90.8%); in the other families, WGS included parents and at least two affected siblings. In the secondary analyses, we evaluated the contribution of rare variant enrichment in particular gene sets, and calculated polygenic risk score (PRS) for schizophrenia. For the primary outcome, diagnostic rate was 6.4%; we found clinically significant, single nucleotide variants (SNVs) or small insertions or deletions (indels) in 14 probands (5.6%), and copy number variants (CNVs) in 2 (0.8%). Significant enrichment of rare loss-of-function variants was observed in a gene set of top schizophrenia candidate genes in affected individuals, compared with population controls (N = 6,840). The PRS for schizophrenia was significantly increased in the affected individuals group, compared to their unaffected relatives. Last, we were also able to provide pharmacogenomics information based on CYP2D6 genotype data for most participants, and determine their antipsychotic metabolizer status. In conclusion, our findings suggest that WGS may have a role in the setting of both research and genetic counseling for individuals with schizophrenia and other psychotic disorders and their families.

Dutch Pharmacogenetics Working Group (DPWG) guideline for the gene-drug interaction between CYP2C19 and CYP2D6 and SSRIs.

The Dutch Pharmacogenetics Working Group (DPWG) guideline presented here, presents the gene-drug interaction between the genes CYP2C19 and CYP2D6 and antidepressants of the selective serotonin reuptake inhibitor type (SSRIs). Both genes' genotypes are translated into predicted normal metabolizer (NM), intermediate metabolizer (IM), poor metabolizer (PM), or ultra-rapid metabolizer (UM). Evidence-based dose recommendations were obtained, based on a structured analysis of published literature. In CYP2C19 PM patients, escitalopram dose should not exceed 50% of the normal maximum dose. In CYP2C19 IM patients, this is 75% of the normal maximum dose. Escitalopram should be avoided in UM patients. In CYP2C19 PM patients, citalopram dose should not exceed 50% of the normal maximum dose. In CYP2C19 IM patients, this is 70% (65-75%) of the normal maximum dose. In contrast to escitalopram, no action is needed for CYP2C19 UM patients. In CYP2C19 PM patients, sertraline dose should not exceed 37.5% of the normal maximum dose. No action is needed for CYP2C19 IM and UM patients. In CYP2D6 UM patients, paroxetine should be avoided. No action is needed for CYP2D6 PM and IM patients. In addition, no action is needed for the other gene-drug combinations. Clinical effects (increase in adverse events or decrease in efficacy) were lacking for these other gene-drug combinations. DPWG classifies CYP2C19 genotyping before the start of escitalopram, citalopram, and sertraline, and CYP2D6 genotyping before the start of paroxetine as "potentially beneficial" for toxicity/effectivity predictions. This indicates that genotyping prior to treatment can be considered on an individual patient basis.

CYP2D6 Genotyping and Antipsychotic-Associated Extrapyramidal Adverse Effects in a Randomized Trial of Aripiprazole Versus Quetiapine Extended Release in Children and Adolescents, Aged 12-17 Years, With First Episode Psychosis.

The aim of this study was to examine the association between genetically predicted CYP2D6 phenotypes and extrapyramidal symptoms (EPSs). Data from the Tolerability and Efficacy of Antipsychotics trial of adolescents with first-episode psychosis randomized to aripiprazole versus quetiapine extended release were studied. Extrapyramidal symptom assessments included the Simpson-Angus Scale and the Barnes Akathisia Rating Scale. Patients were CYP2D6 genotyped. Plasma concentrations of antipsychotics and antidepressants were analyzed. One hundred thirteen youths (age, 12-17 years; males, 30%; antipsychotic naive, 51%) were enrolled. Poor metabolizers had a significantly higher dose-adjusted aripiprazole plasma concentration (±SD) compared with normal metabolizers at week 4 (24.30 ± 6.40 ng/mL per milligram vs 14.85 ± 6.15 ng/mL per milligram; P = 0.019), but not at week 12 (22.15 ± 11.04 ng/mL per milligram vs 14.32 ± 4.52 ng/mL per milligram; P = 0.067). This association was not found in the quetiapine extended release group. No association between CYP2D6 genotype groups and global Barnes Akathisia Rating Scale score or Simpson-Angus Scale score was found in any of the treatment arms. Our results do not support routine use of CYP2D6 testing as a predictor of drug-induced parkinsonism or akathisia risk in clinical settings. Further studies with larger samples of CYP2D6 poor metabolizers are needed.

Influence of CYP2D6 metabolizer status on ondansetron efficacy in pediatric patients undergoing hematopoietic stem cell transplantation: A case series.

Chemotherapy‐induced nausea and vomiting (CINV) is commonly experienced by patients receiving antineoplastic agents prior to hemopoietic stem cell transplant (HSCT). Ondansetron, a 5‐HT3 antagonist metabolized by CYP2D6, is an antiemetic prescribed to treat short‐term CINV, but some patients still experience uncontrolled nausea and vomiting while taking ondansetron. Adult CYP2D6 ultrarapid metabolizers (UMs) are at higher risk for CINV due to rapid ondansetron clearance, but similar studies have not been performed in pediatric patients. We performed a retrospective chart review of 128 pediatric HSCT recipients who received ondansetron for CINV prevention and had CYP2D6 genotyping for 20 alleles and duplication detection. The number of emetic episodes for each patient was collected from the start of chemotherapy through 7 days after HSCT. The average age of the cohort was 6.6 years (range: 0.2–16.7) and included three UMs, 72 normal metabolizers, 47 intermediate metabolizers, and six poor metabolizers. Because UMs are the population at risk for inefficacy, we describe the course of treatment for these three patients, as well as the factors influencing emesis: chemotherapy emetogenicity, diagnosis, and duration of ondansetron administration. The cases described support guidelines recommending non‐CYP2D6 metabolized antiemetics (e.g., granisetron) when a patient is a known CYP2D6 UM, but pediatric studies with a larger sample of CYP2D6 UMs are needed to validate our findings.

Impact of Updating Pharmacogenetic Results: Lessons Learned from the PREDICT Program.

Pharmacogenomic (PGx) evidence for selective serotonin reuptake inhibitors (SSRIs) continues to evolve. For sites offering testing, maintaining up-to-date interpretations and implementing new clinical decision support (CDS) driven by existing results creates practical and technical challenges. Vanderbilt University Medical Center initiated panel testing in 2010, added CYP2D6 testing in 2017, and released CDS for SSRIs in 2020. We systematically reinterpreted historic CYP2C19 and CYP2D6 genotypes to update phenotypes to current nomenclature and to launch provider CDS and patient-oriented content for SSRIs. Chart review was conducted to identify and recontact providers caring for patients with current SSRI therapy and new actionable recommendations. A total of 15,619 patients’ PGx results were reprocessed. Of the non-deceased patients reprocessed, 21% (n = 3278) resulted in CYP2C19*1/*17 reinterpretations. Among 289 patients with an actionable recommendation and SSRI medication prescription, 31.8% (n = 92) did not necessitate contact of a clinician, while 43.2% (n = 125) resulted in clinician contacted, and for 25% (n = 72) no appropriate clinician was able to be identified. Maintenance of up-to-date interpretations and recommendations for PGx results over the lifetime of a patient requires continuous effort. Reprocessing is a key strategy for maintenance and expansion of PGx content to be periodically considered and implemented.

Could Cytochrome P450 2D6, 3A4 and 3A5 Polymorphisms Explain the Variability in Clinical Response to Clomiphene Citrate of Anovulatory PCOS Women?

IntroductionCytochrome P450 2D6, 3A4 and 3A5 are involved in the metabolism of many drugs. These enzymes have a genetic polymorphism responsible for different metabolic phenotypes. They play a role in the metabolism of clomiphene citrate (CC), which is used to induce ovulation. Response to CC treatment is variable, and no predictive factors have thus far been identified.ObjectiveTo study a possible link between the cytochrome P450 2D6, 3A4 and 3A5 polymorphisms and clinical response to CC.Study DesignSeventy-seven women with anovulatory Polycystic Ovarian Syndrome (PCOS) treated with CC were included which determined their cytochrome P450 2D6, 3A4 and 3A5 genotypes and used the results to predict ovarian response to this drug. Predicted responses based on the cytochrome genotypes were compared with the observed clinical responses using the calculation of a weighted Kappa coefficient.Main Outcome MeasuresNumber of dominant follicles assessed by ultrasound at the end of the follicular phase and confirmation of ovulation by blood progesterone assay in the luteal phase.ResultsConcordance between the predicted and observed responses for the combination of the three cytochromes was 36.71%, with a negative Kappa coefficient (K = -0.0240), which corresponds to a major disagreement. Similarly, for predictions based on the cytochrome P450 2D6 genotype alone, only 39.24% of predictions were verified (coefficient K = -0.0609).ConclusionThe genetic polymorphism of cytochromes P450 2D6, 3A4 and 3A5 does not appear to influence clinical response to CC used to induce ovulation in anovulatory PCOS women.

Impact of CYP2D6 Pharmacogenomic Status on Pain Control Among Opioid-Treated Oncology Patients.

Several opioids have pharmacogenomic associations impacting analgesic efficacy. However, germline pharmacogenomic testing is not routinely incorporated into supportive oncology. We hypothesized that CYP2D6 profiling would correlate with opioid prescribing and hospitalizations. We analyzed 61,572 adult oncology patients from 2012 to 2018 for opioid exposures. CYP2D6 metabolizer phenotype (ultra-rapid [UM], normal metabolizer [NM], intermediate [IM], or poor [PM]), the latter two of which may cause inefficacy of codeine, tramadol, and standard-dose hydrocodone, was determined for patients genotyped for reasons unrelated to pain. The primary endpoint was number of opioid medications received during longitudinal care (IM/PMs vs. NMs). Secondary endpoint was likelihood of pain-related hospital encounters. Most patients with cancer (n= 34,675, 56%) received multiple opioids (average 2.8± 1.6/patient). Hydrocodone was most commonly prescribed (62%), followed by tramadol, oxycodone, and codeine. In the CYP2D6 genotyped cohort (n= 105), IM/PMs received a similar number of opioids (3.4± 1.4) as NMs (3.3± 1.9). However, IM/PMs were significantly more likely to experience pain-related hospital encounters compared with NMs, independent of other variables (odds ratio [OR]= 5.4; 95% confidence interval [CI], 1.2-23.6; p=.03). IM/PMs were also more likely to be treated with later-line opioids that do not require CYP2D6 metabolism, such as morphine and hydromorphone (OR=3.3; 95% CI, 1.1-9.8; p=.03). CYP2D6 genotype may identify patients with cancer at increased risk for inadequate analgesia when treated with typical first-line opioids like codeine, tramadol, or standard-dose hydrocodone. Palliative care considerations are an integral part of optimal oncology care, and these findings justify prospective evaluation of preemptive genotyping as a strategy to improve oncology pain management. Genomic variation in metabolic enzymes can predispose individuals to inefficacy when receiving opioid pain medications. Patients with intermediate and/or poor CYP2D6 metabolizer status do not adequately convert codeine, tramadol, and hydrocodone into active compounds, with resulting increased risk of inadequate analgesia. This study showed that patients with cancer frequently receive CYP2D6-dependent opioids. However, patients with CYP2D6 intermediate and poor metabolizer status had increased numbers of pain-related hospitalizations and more frequently required the potent non-CYP2D6 opioids morphine and hydromorphone. This may reflect inadequate initial analgesia with the common "first-line" CYP2D6-metabolized opioids. Preemptive genotyping to guide opioid prescribing during cancer care may improve pain-related patient outcomes.

Metabolomics reveals biomarkers in human urine and plasma to predict cytochrome P450 2D6 (CYP2D6) activity.

Background and PurposeIndividualized assessment of cytochrome P450 2D6 (CYP2D6) activity is usually performed through phenotyping following administration of a probe drug to measure the enzyme's activity. To avoid any iatrogenic harm (allergic drug reaction, dosing error) related to the probe drug, the development of non‐burdensome tools for real‐time phenotyping of CYP2D6 could significantly contribute to precision medicine. This study focuses on the identification of markers of the CYP2D6 enzyme in human biofluids using an LC‐high‐resolution mass spectrometry‐based metabolomic approach.Experimental ApproachPlasma and urine samples from healthy volunteers were analysed before and after intake of a daily dose of paroxetine 20 mg over 7 days. CYP2D6 genotyping and phenotyping, using single oral dose of dextromethorphan 5 mg, were also performed in all participants.Key ResultsWe report four metabolites of solanidine and two unknown compounds as possible novel CYP2D6 markers. Mean relative intensities of these features were significantly reduced during the inhibition session compared with the control session (n = 37). Semi‐quantitative analysis showed that the largest decrease (−85%) was observed for the ion m/z 432.3108 normalized to solanidine (m/z 398.3417). Mean relative intensities of these ions were significantly higher in the CYP2D6 normal–ultrarapid metabolizer group (n = 37) compared with the poor metabolizer group (n = 6). Solanidine intensity was more than 15 times higher in CYP2D6‐deficient individuals compared with other volunteers.Conclusion and ImplicationsThe applied untargeted metabolomic strategy identified potential novel markers capable of semi‐quantitatively predicting CYP2D6 activity, a promising discovery for personalized medicine.