Genotyping av pasienter behandlet med selektive serotoninreopptakshemmere

BAKGRUNN - Selektive serotoninreopptakshemmere (SSRI) brukes av over 180 000 mennesker i Norge. Enzymene CYP2D6 og CYP2C19 er sentrale i metabolismen av SSRI-antidepressiver. Serotonintransportøren kodet av SLC6A4 kan ha betydning for effekten av medikamentene. MATERIALE OG METODE - Alle pasienter som hadde blitt genotypet for CYP2D6, CYP2C19 og SLC6A4 ved Senter for psykofarmakologi i 2020, uavhengig av indikasjon, ble inkludert. Hos de pasientene der data var tilgjengelige, ble CYP2C19-genotype koblet til serumkonsentrasjonsmåling av escitalopram, som er det mest brukte SSRI-preparatet. RESULTATER - 432 av 3 492 pasienter (12,4 %) hadde en kombinasjon av genotyper av CYP2D6, CYP2C19 og SLC6A4 som anses å gi mest gunstig metabolisme og effekt av SSRI-antidepressiver. Pasienter med manglende CYP2C19-metabolisme hadde mer enn halvert dosebehov for å oppnå samme konsentrasjon av escitalopram som pasienter med normal metabolisme. FORTOLKNING - Våre funn viser lav forekomst av den gunstigste genotypekombinasjonen for respons av SSRI-preparater. Genotypekombinasjoner bidrar sannsynligvis til den store individuelle variasjonen i effekt av disse medikamentene og til at behandlingen ikke gir ønsket utfall hos mange pasienter

Impact of NFIB and CYP1A variants on clozapine serum concentration—A retrospective naturalistic cohort study on 526 patients with known smoking habits

Clinical response of clozapine is closely associated with serum concentration. Although tobacco smoking is the key environmental factor underlying interindividual variability in clozapine metabolism, recent genome-wide studies suggest that CYP1A and NFIB genetic variants may also be of significant importance, but their quantitative impact is unclear. We investigated the effects of the rs2472297 C>T (CYP1A) and rs28379954 T>C (NFIB) polymorphisms on serum concentrations in smokers and nonsmokers. The study retrospectively included 526 patients with known smoking habits (63.7% smokers) from a therapeutic drug monitoring service in Norway. Clozapine dose-adjusted concentrations (C/D) and patient proportions with subtherapeutic levels (<1070 nmol/L) were compared between CYP1A/NFIB variant allele carriers and homozygous wild-type carriers (noncarriers), in both smokers and nonsmokers. Clozapine C/D was reduced in patients carrying CYP1A-T and NFIB-C variants versus noncarriers, both among smokers (−48%; p < 0.0001) and nonsmokers (−35%; p = 0.028). Patients who smoke carrying CYP1A-T and NFIB-C variants had a 66% reduction in clozapine C/D versus nonsmoking noncarriers (p < 0.0001). The patient proportion with subtherapeutic levels was 2.9-fold higher in patients who smoke carrying NFIB-C and CYP1A-T variants versus nonsmoking noncarriers (p < 0.0001). In conclusion, CYP1A and NFIB variants have significant and additive impact on clozapine dose requirements for reaching target serum concentrations. Patients who smoke carrying the studied CYP1A and NFIB variants, comprising 2.5% of the study population, may need threefold higher doses to prevent risk of clozapine undertreatment. The results suggest that pre-emptive genotyping of NFIB and CYP1A may be utilized to guide clozapine dosing and improve clinical outcomes in patients with treatment-resistant schizophrenia. © 2022 The Authors. Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics

What is the Current Clinical Impact of the CYP2CTG Haplotype?

We read with great interest the paper by Zubiaur et al.1 on the analysis of a genotype–phenotype relationship of the CYP2C:TG haplotype. This study, including 225 patients receiving one of 6 different drugs and liver pieces from 135 children (median age 7 years), is in contrast to 2 studies by Bråten et al. using in vivo data from 875 escitalopram-treated2 and 840 sertraline-treated3 Norwegian patients, respectively, in which significantly increased rate (+20 to 25%) of CYP2C19-dependent metabolism of these drugs was found for the CYP2C:TGhaplotype

Impact of the novel CYP2C:TG haplotype and CYP2B6 variants on sertraline exposure in a large patient population

Sertraline is a commonly used SSRI antidepressant drug, metabolized by CYP2C19 and CYP2B6, that exhibits a substantial interindividual variation in clinical response, of which only a part can be attributed to known genetic variants. In the current study we have examined the role of a newly discovered ultrarapid CYP2C:TG haplotype and CYP2B6 variants in order to identify the possible missing heritability for such variation in sertraline response in a large patient population (n = 840). Compared to the reference group (CYP2C19*1/*1, n = 160), sertraline exposure was increased by 128% in CYP2C19 PMs (n = 29, p < 0.001) and decreased by about 20% in CYP2C19 ultrarapid metabolizers (UMs) (homozygous carriers of CYP2C19*17 and/or CYP2C:TG haplotype) with the diplotypes CYP2C19*17/*17, CYP2C:TG/TG, or CYP2C19*17/CYP2C:TG (n = 135, p < 0.003, p = 0.022, p < 0.003, respectively). Interestingly, in patients carrying the increased function CYP2B6*4 allele, and also carrying the CYP2C19*17 and CYP2C:TG alleles (n = 10), sertraline exposure was 35.4% lower compared to the reference group, whereas in subjects being poor metabolizers (PM) in both the CYP2C19 and CYP2B6 gene, the sertraline concentrations were raised by 189%. In summary, the CYP2C19 variants including the CYP2C:TG haplotype had a significant impact on sertraline metabolism, as well as the CYP2B6*4, *6, and *9 alleles. Knowing the CYP2B6 and CYP2C19 genotype, including the CYP2C:TG haplotype status, can prospectively be useful to clinicians in making more appropriate sertraline dosing decisions

Effect of the NFIB rs28379954 T>C polymorphism on CYP2D6‐catalyzed metabolism of solanidine

Abstract Cytochrome P450 2D6 (CYP2D6) is important for metabolism of 20%–25% of all clinically used drugs. Many known genetic variants contribute to the large interindividual variability in CYP2D6 metabolism, but much is still unexplained. We recently described that nuclear factor 1B (NFIB) regulates hepatic CYP2D6 expression with the minor allele of NFIB rs28379954 T>C significantly increasing CYP2D6‐mediated risperidone metabolism. In this study, we investigated the effect of NFIB T>C on metabolism of solanidine, a dietary CYP2D6 substrate. Analyses of solanidine and metabolites (M414, M416, and M444) were performed by ultra‐high performance liquid chromatography‐high‐resolution mass spectrometry in a cohort of 463 CYP2D6‐genotyped patients of which with 58 (12.5%) carried NFIB TC (n = 56) or CC (n = 2). Increased metabolism of solanidine was found in CYP2D6 normal metabolizers (NMs; n = 258, 55.7%) carrying the NFIB C variant (n = 27, 5.8%) with 2.83‐ and 3.38‐fold higher M416‐to‐solanidine (p = 0.039) and M444‐to‐solanidine (p = 0.046) ratios, respectively, whereas this effect was not significant among intermediate metabolizers (n = 166, 35.9%) (p ≥ 0.09). Importantly, no effect of the NFIB polymorphism on solanidine metabolism was seen in TC or CC carriers lacking CYP2D6 activity (poor metabolizers, n = 30, 6.5%, p ≥ 0.74). Furthermore, the NFIB polymorphism significantly explained variability in solanidine metabolism (M414 p = 0.013, M416 p = 0.020, and M416 and M444 p = 0.009) in multiple linear regression models for each metabolic ratio in the entire population, correcting for covariates (including CYP2D6 genotypes). Thus, the study confirms the effect of NFIB in regulating CYP2D6 activity, suggesting an about 200% increase in CYP2D6‐mediated clearance in NMs being NFIB CT or CC carriers, comprising around 6% of Europeans