Genetic variations of the xenoreceptors NR1I2 and NR1I3 and their effect on drug disposition and response variability

NR1I2 as a core biological target in chronic venous ulcer tissues treated with ultrasound therapy

Ultrasound therapy is a method of applying ultrasonic energy to the stimulation produced by human body to change the function and tissue state of the body in order to achieve the purpose of treating diseases. Chronic venous ulcer is a common chronic skin ulcer. GSE222503 for ultrasound therapy of chronic venous ulcers was downloaded from gene expression omnibus database, which were used to identify differentially expressed genes. Weighted gene co-expression network analysis, functional enrichment analysis, gene set enrichment analysis, immune infiltration analysis and construction and analysis of protein-protein interaction network were performed. Draw gene expression heatmaps. Comparative toxicogenomics database analysis was performed. Two hundred thirty-five differentially expressed genes were obtained. According to gene ontology analysis, in biological process analysis, they were mainly enriched in positive regulation of cellular biosynthetic process, reproductive cell development, vasculogenesis, vascular morphogenesis, and inflammatory response. In cellular component analysis, they were mainly enriched in leading edge of growing cell, extracellular matrix binding organelle, F-actin capping protein complex. In molecular function analysis, they were mainly concentrated in receptor ligand activity, cytokine receptor binding. In Kyoto encyclopedia of genes and genomes analysis, they were mainly enriched in cytokine-cytokine receptor interaction, PI3K-Akt signaling pathway, HIF-1 signaling pathway, heme biosynthesis. In weighted gene co-expression network analysis, the soft threshold power was set to 9. Thirty modules were generated. PF4, NR1I2, TTC16, H3C12, KLRB1, CYP21A2 identified by 4 algorithms (MCC, EPC, closeness, stress). Heatmap of core gene expression showed that H3C12, KLRB1, PF4, NR1I2 were all underexpressed in samples of ultrasound-treated chronic venous ulcers and overexpressed in samples of untreated chronic venous ulcers. Comparative toxicogenomics database analysis showed that H3C12, KLRB1, PF4, NR1I2 are associated with thrombophlebitis, phlebitis, vascular malformations, metabolic syndrome, ulcers, and inflammation. In samples of chronic venous ulcer tissue treated with ultrasound, NR1I2 shows low expression, while in samples of chronic venous ulcer tissue without ultrasound treatment, it shows high expression. This finding suggests a potential role of NR1I2 in the process of ultrasound therapy for chronic venous ulcers, which may be related to the therapeutic effect of ultrasound therapy on chronic venous ulcers.

Genetic polymorphisms of CYP2B6 is a risk of metabolic associated fatty liver disease in Chinese population

BACKGROUND

The expression and activity of cytochrome P450 2B6 (CYP2B6) may be related to the metabolic associated fat liver disease (MAFLD). Since constitutive androstane receptor (CAR) is a classic transcriptional regulator of CYP2B6, and the single nucleotide polymorphisms (SNPs) of CYP2B6 and CAR are both associated with adverse reactions of efavirenz, we hypothesized that genetic polymorphisms of CAR might also result in additional interindividual variability in CYP2B6. This study was devoted to explore the association between CYP2B6 and CAR SNPs and susceptibility to MAFLD.

MATERIALS AND METHODS

A total of 590 objects of study (118 with MAFLD and 472 healthy control) between December 2014 and April 2018 were retrospectively enrolled. Twenty-two selected SNPs in CYP2B6 and CAR were genotyped with a custom-designed 48-plex SNP Scan TM® Kit. The frequencies of the alleles, genotypes and genetic models of the variants were compared between the two groups. The odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) were calculated.

RESULTS

The T allele of rs3745274 in CYP2B6 was associated with a decreased risk for MAFLD (OR 0.610; 95% CI: 0.451-0.825, p = 0.001) which was still statistically significant after adjusting with Bonferroni method(p = 0.014) The allele, genotype and genetic model frequencies were similar in the two groups for the other twenty-one SNPs (all P > 0.05). There were no multiplicative or additive interactions between the SNPs.

CONCLUSION

Our study revealed that rs3745274 variants in CYP2B6 is associated with susceptibility to MAFLD in the Han Chinese population.

Impacts of pregnane X receptor and cytochrome P450 oxidoreductase gene polymorphisms on trough concentrations of apixaban in patients with non-valvular atrial fibrillation

PURPOSE

We examined the impact of polymorphisms in genes encoding cytochrome P450 (CYP) 3A5 (gene code CYP3A5), P-glycoprotein (ABCB1), breast cancer resistance protein (ABCG2), cytochrome P450 oxidoreductase (POR), and pregnane X receptor (PXR; NR1I2) on the daily dose-adjusted steady-state trough concentrations (C_0h/D) of apixaban.

METHODS

The analyses included 104 patients with non-valvular atrial fibrillation (NVAF) undergoing AF catheter ablation. The CYP3A5*3; ABCG2 421C > A; ABCB1 1236C > T, 2677G > A/T, 3435C > T, and 2482-2236G > A; NR1I2 11156A > C, 11193T > C, and 8055C > T; and POR*28 genotypes were determined. The combination of the noted NR1I2 genotypes determined the PXR*1B haplotype.

RESULTS

Multiple linear regression analyses demonstrated that decreased creatinine clearance (Ccr) and the PXR*1B/*1B haplotype correlated with increased C_0h/D of apixaban, while the presence of the POR*28 allele correlated with decreased C_0h/D of apixaban (partial R² = 0.168, 0.029, and 0.044, all P < 0.05). The mean (95% CI) of estimated marginal means of apixaban C_0h/D calculated using Ccr as a covariate was the highest in POR*28 noncarriers with PXR*1B/*1B (23.5 [21.0-25.9] ng/mL/[mg/day]) and lowest in POR*28 carriers with other haplotypes (16.6 [15.5-17.7] ng/mL/[mg/day]).

CONCLUSION

The PXR*1B haplotype and POR*28 genotype statuses, which involve genes that impact the expression of multiple drug-metabolizing enzymes and drug-transporters, may have modest effects on the C_0h/D of apixaban, but these effects were found to be small.

Role of Genetic Polymorphisms in Drug-Metabolizing Enzyme-Mediated Toxicity and Pharmacokinetic Resistance to Anti-Cancer Agents: A Review on the Pharmacogenomics Aspect

The inter-individual differences in cancer susceptibility are somehow correlated with the genetic differences that are caused by the polymorphisms. These genetic variations in drug-metabolizing enzymes/drug-inactivating enzymes may negatively or positively affect the pharmacokinetic profile of chemotherapeutic agents that eventually lead to pharmacokinetic resistance and toxicity against anti-cancer drugs. For instance, the CYP1B1*3 allele is associated with CYP1B1 overexpression and consequent resistance to a variety of taxanes and platins, while 496T>G is associated with lower levels of dihydropyrimidine dehydrogenase, which results in severe toxicities related to 5-fluorouracil. In this context, a pharmacogenomics approach can be applied to ascertain the role of the genetic make-up in a person's response to any drug. This approach collectively utilizes pharmacology and genomics to develop effective and safe medications that are devoid of resistance problems. In addition, recently reported genomics studies revealed the impact of many single nucleotide polymorphisms in tumors. These studies emphasized the importance of single nucleotide polymorphisms in drug-metabolizing enzymes on the effect of anti-tumor drugs. In this review, we discuss the pharmacogenomics aspect of polymorphisms in detail to provide an insight into the genetic manipulations in drug-metabolizing enzymes that are responsible for pharmacokinetic resistance or toxicity against well-known anti-cancer drugs. Special emphasis is placed on different deleterious single nucleotide polymorphisms and their effect on pharmacokinetic resistance. The information provided in this report may be beneficial to researchers, especially those who are working in the field of biotechnology and human genetics, in rationally manipulating the genetic information of patients with cancer who are undergoing chemotherapy to avoid the problem of pharmacokinetic resistance/toxicity associated with drug-metabolizing enzymes.

Why We Need to Take a Closer Look at Genetic Contributions to CYP3A Activity

Cytochrome P450 3A (CYP3A) subfamily enzymes are involved in the metabolism of 40% of drugs in clinical use. Twin studies have indicated that 66% of the variability in CYP3A4 activity is hereditary. Yet, the complexity of the CYP3A locus and the lack of distinct drug metabolizer phenotypes has limited the identification and clinical application of CYP3A genetic variants compared to other Cytochrome P450 enzymes. In recent years evidence has emerged indicating that a substantial part of the missing heritability is caused by low frequency genetic variation. In this review, we outline the current pharmacogenomics knowledge of CYP3A activity and discuss potential future directions to improve our genetic knowledge and ability to explain CYP3A variability.

Constitutive androstane receptor and pregnane X receptor genotype influence efavirenz plasma concentration and CYP2B6 enzyme activity

Efavirenz is metabolized by CYP2B6, an inducible enzyme whose expression is regulated by the constitutive androstane receptor and pregnane X receptor nuclear receptors. CAR and PXR are encoded by genetically polymorphic NR1I2 and NR1I3, respectively. We examined the impact of NR1I2 and NR1I3 genotype on plasma EFV concentration and CYP2B6 enzyme activity among TB-HIV co-infected patients in Ethiopia. Treatment-naïve HIV patients with TB co-infection (n = 80) were enrolled and received first-line EFV-based antiretroviral and rifampicin-based anti-TB therapy. Plasma EFV and 8-hydroxy-EFV concentrations at the 4th and 16th week of EFV treatment were determined using LC/MS/MS. EFV/8-hydroxy-EFVmetabolic ratio was used as CYP2B6 metabolic activity index. In multivariate regression analysis, NR1I3 rs3003596C or NR1I2 rs2472677T variant allele carriers had significantly lower plasma EFV concentrations than non-carriers. Patients with NR1I2 rs3814057C/C genotype or NR1I3 rs3003596C allele carriers had significantly lower mean log EFV MR. Among CYP2B6*6 allele carriers, patients with NR1I3 rs2502815T/T or NR1I2 rs3814057C/C genotype had significantly lower mean log EFV MR. In conclusion, genetic variants in NR1I2 and NR1I3 genes influence plasma EFV exposure and CYP2B6 enzyme activity in TB-HIV co-infected patients on drug treatment.

Regulation of Drug Transport Proteins-From Mechanisms to Clinical Impact: A White Paper on Behalf of the International Transporter Consortium

Membrane transport proteins are involved in the absorption, disposition, efficacy, and/or toxicity of many drugs. Numerous mechanisms (e.g., nuclear receptors, epigenetic gene regulation, microRNAs, alternative splicing, post‐translational modifications, and trafficking) regulate transport protein levels, localization, and function. Various factors associated with disease, medications, and dietary constituents, for example, may alter the regulation and activity of transport proteins in the intestine, liver, kidneys, brain, lungs, placenta, and other important sites, such as tumor tissue. This white paper reviews key mechanisms and regulatory factors that alter the function of clinically relevant transport proteins involved in drug disposition. Current considerations with in vitro and in vivo models that are used to investigate transporter regulation are discussed, including strengths, limitations, and the inherent challenges in predicting the impact of changes due to regulation of one transporter on compensatory pathways and overall drug disposition. In addition, translation and scaling of in vitro observations to in vivo outcomes are considered. The importance of incorporating altered transporter regulation in modeling and simulation approaches to predict the clinical impact on drug disposition is also discussed. Regulation of transporters is highly complex and, therefore, identification of knowledge gaps will aid in directing future research to expand our understanding of clinically relevant molecular mechanisms of transporter regulation. This information is critical to the development of tools and approaches to improve therapeutic outcomes by predicting more accurately the impact of regulation‐mediated changes in transporter function on drug disposition and response.

Impact of polymorphisms of pharmacokinetics-related genes and the inflammatory response on the metabolism of voriconazole

The effects of inflammatory responses and polymorphisms of the genes encoding cytochrome P450 (CYP) (CYP2C19 and CYP3A5), flavin-containing monooxygenase 3 (FMO3), pregnane X receptor (NR1I2), constitutive androstane receptor (NR1I3), and CYP oxidoreductase (POR) on the ratio of voriconazole (VRCZ) N-oxide to VRCZ (VNO/VRCZ) and steady-state trough concentrations (C_0h ) of VRCZ were investigated. A total of 56 blood samples were collected from 36 Japanese patients. Results of multiple linear regression analyses demonstrated that the presence of the extensive metabolizer CYP2C19 genotype, the dose per administration, and the presence of the NR1I2 rs3814057 C/C genotype were independent factors influencing the VNO/VRCZ ratio in patients with CRP levels of less than 40 mg/L (standardized regression coefficients (SRC) = 0.448, -0.301, and 0.390, respectively; all p < .05). With regard to the concentration of VRCZ itself, in addition to the above factors, the presence of the NR1I2 rs7643645 G/G and rs3814055 T/T genotypes were found to be independent factors influencing the VRCZ C_0h in these patients (SRC = -0.430, 0.424, -0.326, 0.406 and -0.455, respectively; all p < .05). On the contrary, in patients with CRP levels of at least 40 mg/L, no independent factors were found to affect VNO/VRCZ and VRCZ C_0h . Inflammatory responses, and CYP2C19 and NR1I2 polymorphisms may be useful information for the individualization of VRCZ dosages.

The Nuclear Receptor PXR in Chronic Liver Disease

Pregnane X receptor (PXR), a nuclear receptor known for modulating the transcription of drug metabolizing enzymes and transporters (DMETs), such as cytochrome P450 3A4 and P-glycoprotein, is functionally involved in chronic liver diseases of different etiologies. Furthermore, PXR activity relates to that of other NRs, such as constitutive androstane receptor (CAR), through a crosstalk that in turn orchestrates a complex network of responses. Thus, besides regulating DMETs, PXR signaling is involved in both liver damage progression and repair and in the neoplastic transition to hepatocellular carcinoma. We here summarize the present knowledge about PXR expression and function in chronic liver diseases characterized by different etiologies and clinical outcome, focusing on the molecular pathways involved in PXR activity. Although many molecular details of these finely tuned networks still need to be fully understood, we conclude that PXR and its modulation could represent a promising pharmacological target for the identification of novel therapeutical approaches to chronic liver diseases.

A forward genetic screen identifies modifiers of rocaglate responsiveness

Rocaglates are a class of eukaryotic translation initiation inhibitors that are being explored as chemotherapeutic agents. They function by targeting eukaryotic initiation factor (eIF) 4A, an RNA helicase critical for recruitment of the 40S ribosome (and associated factors) to mRNA templates. Rocaglates perturb eIF4A activity by imparting a gain-of-function activity to eIF4A and mediating clamping to RNA. To appreciate how rocaglates could best be enabled in the clinic, an understanding of resistance mechanisms is important, as this could inform on strategies to bypass such events as well as identify responsive tumor types. Here, we report on the results of a positive selection, ORFeome screen aimed at identifying cDNAs capable of conferring resistance to rocaglates. Two of the most potent modifiers of rocaglate response identified were the transcription factors FOXP3 and NR1I3, both of which have been implicated in ABCB1 regulation-the gene encoding P-glycoprotein (Pgp). Pgp has previously been implicated in conferring resistance to silvestrol, a naturally occurring rocaglate, and we show here that this extends to additional synthetic rocaglate derivatives. In addition, FOXP3 and NR1I3 impart a multi-drug resistant phenotype that is reversed upon inhibition of Pgp, suggesting a potential therapeutic combination strategy.

Pregnane X Receptor (PXR) Polymorphisms and Cancer Treatment

Pregnane X Receptor (PXR) belongs to the nuclear receptors’ superfamily and mainly functions as a xenobiotic sensor activated by a variety of ligands. PXR is widely expressed in normal and malignant tissues. Drug metabolizing enzymes and transporters are also under PXR’s regulation. Antineoplastic agents are of particular interest since cancer patients are characterized by significant intra-variability to treatment response and severe toxicities. Various PXR polymorphisms may alter the function of the protein and are linked with significant effects on the pharmacokinetics of chemotherapeutic agents and clinical outcome variability. The purpose of this review is to summarize the roles of PXR polymorphisms in the metabolism and pharmacokinetics of chemotherapeutic drugs. It is also expected that this review will highlight the importance of PXR polymorphisms in selection of chemotherapy, prediction of adverse effects and personalized medicine.

Genetic and Functional Evaluation of the Role of FOXO1 in Antituberculosis Drug-Induced Hepatotoxicity

Background

The accumulation of the hepatotoxic substance protoporphyrin IX (PPIX) induced by aminolevulinate synthase 1 (ALAS1) activation is one of the important mechanisms of antituberculosis drug-induced hepatotoxicity (ATDH). Forkhead box protein O1 (FOXO1) may activate ALAS1 transcription. However, little is known about their roles in ATDH; we performed a study to determine the association between polymorphisms in the two genes and ATDH susceptibility. Then, we verified this possible association by cellular functional experiments.

Materials and Methods

Tag single-nucleotide polymorphisms (TagSNPs) in the two genes were genotyped in 746 tuberculosis patients. The frequencies of the alleles, genotypes, genetic models, and haplotype distribution of the variants were compared between the case and control groups. L-02 cells and HepG2 cells were incubated with the indicated concentration of isoniazid (INH) and rifampicin (RIF) for the desired times, and then the expression levels of ALAS1 and FOXO1 mRNAs and proteins were detected. HepG2 cells were transiently transfected with FOXO1 siRNA to observe the effect of changes in the FOXO1 expression on the cell survival rate and ALAS1 expression.

Results

The C allele at rs2755237 and the T allele at rs4435111 in the FOXO1 gene were associated with a decreased risk of ATDH. The expression of ALAS1 in both L-02 cells and HepG2 cells was increased by the coadministration of INH/RIF (600/200 μM) for 24 h. Although FOXO1 expression was reduced slightly by the same treatment, its content in the nucleus was significantly increased. However, the cell survival rate and ALAS1 expression level were not significantly altered by the downregulation of FOXO1 in HepG2 cells.

Conclusions

Variants of the rs4435111 and rs2755237 loci in the FOXO1 gene were associated with susceptibility to ATDH. Coadministration of INH/RIF promoted the transfer of FOXO1 from the cytoplasm to the nucleus, but the functional significance of its nuclear translocation requires further verification.

Pharmacogenetics and pharmacokinetics modeling of unexpected and extremely severe toxicities after sorafenib intake

A 53-year-old woman with papillary thyroid cancer treated with 800 mg sorafenib therapy rapidly experienced grade 3 toxicities. Dosing was reduced in a step-wise manner with several treatment discontinuations down to 200 mg every 2 days but severe toxicities continued. Plasma drug monitoring showed high exposure, even at low dose. Dosing was then further reduced at 200 mg every 3 days and tolerance was finally acceptable (i.e., grade 1 toxicity) with stable disease upon RECIST imaging. Pharmacogenetic investigations showed polymorphisms affecting both UGT1A9 (UGT1A9-rs3832043) and nuclear receptor PXR (NR1I2-rs3814055, NR1I2-rs2472677 and NR1I2-rs10934498), possibly resulting in downregulation of liver metabolizing enzymes of sorafenib (i.e., CYP and UGT). Patient's clearance (0.48 l/h) estimated by Bayesian approach was consistently lower than usually described. This is the first time that, in addition to mutations affecting UGT1A9, genetic polymorphisms of NR1I2 have possibly been associated with both plasma overexposure and severe toxicities upon sorafenib intake.

Distinct Effects of Inflammation on Cytochrome P450 Regulation and Drug Metabolism: Lessons from Experimental Models and a Potential Role for Pharmacogenetics

Personalized medicine strives to optimize drug treatment for the individual patient by taking into account both genetic and non-genetic factors for drug response. Inflammation is one of the non-genetic factors that has been shown to greatly affect the metabolism of drugs—primarily through inhibition of cytochrome P450 (CYP450) drug-metabolizing enzymes—and hence contribute to the mismatch between the genotype predicted drug response and the actual phenotype, a phenomenon called phenoconversion. This review focuses on inflammation-induced drug metabolism alterations. In particular, we discuss the evidence assembled through human in-vitro models on the effect of inflammatory mediators on clinically relevant CYP450 isoform levels and their metabolizing capacity. We also present an overview of the current understanding of the mechanistic pathways via which inflammation in hepatocytes may modulate hepatic functions that are critical for drug metabolism. Furthermore, since large inter-individual variability in response to inflammation is observed in human in-vitro models and clinical studies, we evaluate the potential role of pharmacogenetic variability in the inflammatory signaling cascade and how this can modulate the outcome of inflammation on drug metabolism and response.

NR1I2 genetic polymorphisms and the risk of anti-tuberculosis drug-induced hepatotoxicity: A systematic review and meta-analysis

Anti-tuberculosis drug-induced hepatotoxicity (ATDH) is a serious adverse drug reaction. Conflicting results have been obtained regarding the associations of nuclear receptor subfamily 1 group I member 2 (NR1I2) gene polymorphisms on susceptibility to ATDH. Therefore, we aimed to evaluate the associations using a systematic review/meta-analysis approach. PubMed, Medline, Cochrane Library, Web of Science and SinoMed databases were searched for all eligible studies from inception to June 10, 2020. Pooled adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were employed to evaluate the strength of the association between the NR1I2 polymorphisms and the risk of ATDH. Subgroup analysis was performed by region of origin, and meta-regression were performed to detect potential sources of heterogeneity. A total of five case-control studies involving 572 cases and 1867 controls were identified. Fourteen SNPs in the NR1I2 gene have been reported, and the most heavily studied SNPs were rs3814055 and rs7643645. The pooled estimates did not exhibit any significant associations between SNPs rs3814055 and rs7643645 and the risk of ATDH (rs3814055: dominant model, OR = 1.00, 95% CI: 0.82-1.22, P = 1.00; recessive model, OR = 1.17, 95% CI: 0.76-1.78, P = .48; rs7643645: dominant model, OR = 1.04, 95% CI: 0.64-1.68, P = .89; recessive model, OR = 0.98, 95% CI: 0.65-1.49, P = .93). Subgroup analysis obtained similar negative results in Chinese patients, and the diagnostic criteria of ATDH may be the source of heterogeneity. Based on the meta-analysis described in this report, we did not observe any association between NR1I2 gene polymorphisms and ATDH susceptibility. However, this conclusion should be interpreted with caution due to the low number of studies and the relatively small sample size.

Metabolism-Disrupting Chemicals and the Constitutive Androstane Receptor CAR

During the last two decades, the constitutive androstane receptor (CAR; NR1I3) has emerged as a master activator of drug- and xenobiotic-metabolizing enzymes and transporters that govern the clearance of both exogenous and endogenous small molecules. Recent studies indicate that CAR participates, together with other nuclear receptors (NRs) and transcription factors, in regulation of hepatic glucose and lipid metabolism, hepatocyte communication, proliferation and toxicity, and liver tumor development in rodents. Endocrine-disrupting chemicals (EDCs) constitute a wide range of persistent organic compounds that have been associated with aberrations of hormone-dependent physiological processes. Their adverse health effects include metabolic alterations such as diabetes, obesity, and fatty liver disease in animal models and humans exposed to EDCs. As numerous xenobiotics can activate CAR, its role in EDC-elicited adverse metabolic effects has gained much interest. Here, we review the key features and mechanisms of CAR as a xenobiotic-sensing receptor, species differences and selectivity of CAR ligands, contribution of CAR to regulation hepatic metabolism, and evidence for CAR-dependent EDC action therein.

Predictors of tacrolimus pharmacokinetic variability: current evidences and future perspectives

INTRODUCTION

In kidney transplantation, tacrolimus (TAC) is at the cornerstone of current immunosuppressive strategies. Though because of its narrow therapeutic index, it is critical to ensure that TAC levels are maintained within this sharp window through reactive adjustments. This would allow maximizing efficiency while limiting drug-associated toxicity. However, TAC high intra- and inter-patient pharmacokinetic (PK) variability makes it more laborious to accurately predict the appropriate dosage required for a given patient.

AREAS COVERED

This review summarizes the state-of-the-art knowledge regarding drug interactions, demographic and pharmacogenetics factors as predictors of TAC PK. We provide a scoring index for each association to grade its relevance and we present practical recommendations, when possible for clinical practice.

EXPERT OPINION

The management of TAC concentration in transplanted kidney patients is as critical as it is challenging. Recommendations based on rigorous scientific evidences are lacking as knowledge of potential predictors remains limited outside of DDIs. Awareness of these limitations should pave the way for studies looking at demographic and pharmacogenetic factors as well as gut microbiota composition in order to promote tailored treatment plans. Therapeutic approaches considering patients' clinical singularities may help allowing to maintain appropriate concentration of TAC.

Variability of voriconazole concentrations in patients with hematopoietic stem cell transplantation and hematological malignancies: influence of loading dose, procalcitonin, and pregnane X receptor polymorphisms

AIMS

Voriconazole (VCZ) displays highly variable pharmacokinetics affecting treatment efficacy and safety. We aimed to identify the factors affecting VCZ steady-state trough concentration (Cssmin) to provide evidence for optimizing VCZ treatment regimens.

METHODS

A total of 510 Cssmin of 172 patients with hematopoietic stem cell transplantation and hematologic malignancies and their clinical characteristics and genotypes of FMO, POR, and PXR were included in this study.

RESULTS

In univariate analysis, the standard loading dose of VCZ significantly increased the Cssmin of VCZ (P < 0.001). The Cssmin of VCZ was significantly correlated with patients' total bilirubin (TB) (P < 0.001) and procalcitonin (PCT) (P < 0.001). FMO3 rs2266780 (P = 0.025), POR rs10954732 (P = 0.015), PXR rs2461817 (P = 0.010), PXR rs7643645 (P = 0.003), PXR rs3732359 (P = 0.014), PXR rs3814057 (P = 0.005), and PXR rs6785049 (P = 0.013) have a significant effect on Cssmin of VCZ. Loading dose, TB, PCT level, and PXRrs3814057 polymorphism were independent influencing factors of VCZ Cssmin in the analysis of multivariate linear regression. And loading dose, PCT, and PXR rs3814057 had significant effects on the probability of the therapeutic window of VCZ.

CONCLUSION

The high variability of VCZ Cssmin may be partially explained by loading dose, liver function, inflammation, and PXR polymorphisms. This study suggests the VCZ standard loading dose regimen significantly increased Cssmin and probability of the therapeutic window providing treatment benefits. Patients in the high PCT group may be more likely to exceed 5.5 μg/mL, thus suffering from VCZ toxicity.

Genetic polymorphisms in PXR and NF-κB1 influence susceptibility to anti-tuberculosis drug-induced liver injury

BACKGROUND

Pregnane X receptor (PXR) regulates the expression of drug-metabolizing enzymes and transport enzymes. NF-κB not only plays a role in liver homeostasis and injury-healing processes by regulating inflammatory responses but may also regulate the transcription of PXR. Currently, genetic polymorphisms in PXR are associated with adverse drug effects. Because little is known about the association between NF-κB1 genetic polymorphisms and adverse drug reactions, we explored the association between PXR and NF-κB1 single nucleotide polymorphisms (SNPs) and susceptibility to anti-tuberculosis drug-induced liver injury (ATDILI).

MATERIALS AND METHODS

A total of 746 tuberculosis patients (118 with ATDILI and 628 without ATDILI) were prospectively enrolled at West China Hospital between December 2014 and April 2018. Nine selected SNPs (rs3814055, rs13059232, rs7643645 and rs3732360 in PXR and rs78872571, rs4647992, rs60371688, rs1598861 and rs3774959 in NF-κB1) were genotyped with a custom-designed 2x48-plex SNP Scan TM Kit. The frequencies of the alleles, genotypes and genetic models of the variants were compared between patients with or without ATDILI, while joint effect analysis of the SNP-SNP interactions was performed using multiplicative and additive models. The odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) were calculated.

RESULTS

The T allele of rs3814055 in PXR was associated with a decreased risk for ATDILI (OR 0.61; 95% CI: 0.42-0.89, p = 0.0098). The T alleles of rs78872571 and rs4647992 in NF-κB1 were significantly associated with an increased risk for ATDILI (OR 1.91; 95% CI: 1.06-3.43, p = 0.028 and OR 1.81; 1.06-3.10, p = 0.029, respectively). The allele, genotype and genetic model frequencies were similar in the two groups for the other six SNPs (all P>0.05). There were no multiplicative or additive interactions between the SNPs.

CONCLUSION

Our study is the first to reveal that rs3814055 variants in PXR and rs78872571 and rs4647992 variants in NF-κB1 are associated with susceptibility to ATDILI caused by first-line anti-tuberculosis combination treatment in the Han Chinese population.

Genetic Polymorphisms and Adverse Events on Unbound Imatinib and Its Active Metabolite Concentration in Patients With Gastrointestinal Stromal Tumors

Imatinib is a first-line drug for the treatment of gastrointestinal stromal tumors (GIST). This study aims to investigate the influence of different kinds of protein concentrations and genetic polymorphisms of metabolizing enzymes and drug transporters on unbound imatinib and its active metabolite N-desmethyl-imatinib concentration, as well as the relationship between adverse drug reactions (ADRs) and drug concentration. A total of 62 Chinese patients with GIST were genotyped for five single nucleotide polymorphisms (SNPs). Total and unbound 3h and trough concentration of imatinib and N-desmethyl-imatinib in GIST patients were determined by an LC-MS/MS method combined with an equilibrium dialysis. Single-Use Red Plate with inserts was used to separate the unbound drug. When the protein concentration became higher, the unbound imatinib and N-desmethyl-imatinib plasma concentration got higher (p < 0.05). Patients with GA genotype in rs755828176 had significantly higher unbound N-desmethyl-imatinib dose-adjusted trough plasma concentrations (p = 0.012). Patients with CC genotype in rs3814055 had significantly higher unbound imatinib dose-adjusted trough plasma concentrations (p = 0.040). The mean total imatinib C_3h of patients with ADRs (3.10 ± 0.96 µg/ml) was significantly higher than that of patients without ADRs (p = 0.023). The mean total N-desmethyl-imatinib C_3h of patients (0.64 ± 0.21 µg/ml) with ADRs was significantly higher than that of patients without ADRs (p = 0.004). The mean unbound N-desmethyl-imatinib C_3h of patients with ADRs (6.49 ± 2.53 ng/ml) was significantly higher than that of patients without ADRs (p = 0.042). The total and unbound C_3h of imatinib and N-desmethyl-imatinib in patients with ADRs was significantly higher than that in patients without ADRs (p < 0.05). Protein concentrations have great influence on the unbound imatinib and N-desmethyl-imatinib concentrations. The genetic polymorphisms of CYP3A4 rs755828176 and NR1I2 rs3814055 were significantly associated with unbound imatinib and N-desmethyl-imatinib dose-adjusted trough plasma levels. The total and unbound imatinib or N-desmethyl-imatinib concentration in patients with GIST was also significantly correlated with ADRs.

Effects of Absence of Constitutive Androstane Receptor (CAR) on Bile Acid Homeostasis in Male and Female Mice

Accumulation of BAs in hepatocytes has a role in liver disease and also in drug-induced liver injury. The Constitutive Androstane Receptor (CAR) has been shown to protect against BA-induced liver injury. The polymorphism of CAR has recently been shown to modify the pharmacokinetics and pharmacodynamics of various drugs. Thus it was hypothesized that polymorphism of CAR may also influence BA homeostasis. Using CAR-null and WT mice, this study modeled the potential consequences of CAR polymorphism on BA homeostasis. Our previous study showed that chemical activation of CAR decreases the total BA concentrations in livers of mice. Surprisingly the absence of CAR also decreased the BA concentrations in livers of mice, but to a lesser extent than in CAR-activated mice. Neither CAR activation nor elimination of CAR altered the biliary excretion of total BAs, but CAR activation increased the proportion of 6-OH BAs (TMCA), whereas the lack of CAR increased the excretion of TCA, TCDCA and TDCA. Serum BA concentrations did not parallel the decrease in BA concentrations in the liver in either the mice after CAR activation or mice lacking CAR. Gene expression of BA synthesis, transporter and regulator genes were mainly similar in livers of CAR-null and WT mice. In summary, CAR activation decreases primarily the 12-OH BA concentrations in liver, whereas lack of CAR decreases the concentrations of 6-OH BAs in liver. In bile, CAR activation increases the biliary excretion of 6-OH BAs, whereas absence of CAR increases the biliary excretion of 12-OH BAs and TCDCA.

The Influence of Pharmacogenetic Variants in HIV/Tuberculosis Coinfected Patients in Uganda in the SOUTH Study

Unsatisfactory treatment outcomes have been reported in patients coinfected with HIV/tuberculosis (TB). The aim of this study was to assess the influence of single-nucleotide polymorphisms (SNPs) in genes encoding for proteins involved in antitubercular drug disposition or effect. A pharmacogenetic study was conducted in Kampala, Uganda, where all analysis was performed. The impact of SNPs on antitubercular drug exposure, adverse events, and treatment outcomes was evaluated in patients coinfected with HIV/TB receiving treatments for both conditions. In 221 participants, N-acetyltransferase 2 (NAT2; rs1799930), solute carrier organic anion transporter family member 1B1 (SLCO1B1; rs4149032), and pregnane X receptor (PXR; rs2472677) variants affected isoniazid exposure in multivariate analysis. Most patients were deemed cured (163; 73.8%), yet PXR 63396TT carriers had a higher probability of death (P = 0.007) and of worsening peripheral neuropathy (P = 0.018). In this exploratory study in Ugandan patients coinfected with HIV/TB, genetic variants in PXR, SLCO1B1, and NAT2 were moderately associated with isoniazid exposure, whereas PXR 63396TT carriers showed worse outcomes.

Drug discovery technologies to identify and characterize modulators of the pregnane X receptor and the constitutive androstane receptor

The pregnane X receptor (PXR) and the constitutive androstane receptor (CAR) are ligand-activated nuclear receptors (NRs) that are notorious for their role in drug metabolism, causing unintended drug-drug interactions and decreasing drug efficacy. They control the xenobiotic detoxification system by regulating the expression of an array of drug-metabolizing enzymes and transporters that excrete exogenous chemicals and maintain homeostasis of endogenous metabolites. Much effort has been invested in recognizing potential drugs for clinical use that can activate PXR and CAR to enhance the expression of their target genes, and in identifying PXR and CAR inhibitors that can be used as co-therapeutics to prevent adverse effects. Here, we present current technologies and assays used in the quest to characterize PXR and CAR modulators, which range from biochemical to cell-based and animal models.

High-throughput blood sample preparation for single nucleotide polymorphism genotyping in less than 25 min

Straightforward, rapid and high-throughput pretreatment for single nucleotide polymorphisms (SNP) genotyping is critically needed in clinical practice. However, all existing SNP genotyping methods require DNA purification step, which is labor-intensive and time-consuming. We develop a protocol for SNP genotyping by combining whole blood lysis (WBL) with qPCR and justify the practicality of our method in blood samples from 140 donors, including 40 samples from healthy donors, and 100 samples from donors with either low white blood cell counts, high level of serum uric acid or triglyceride. When compared with Sanger sequencing, the gold standard for SNP genotyping, our method exhibits a 100% consistency in the aspect of sensitivity and specificity. In addition, our method can obtain amplifiable DNA within 25 mins (which is the fastest to the best of our knowledge) from 48 samples. The blood samples, even with low white blood cell counts, high level of serum uric acid or triglyceride could not affect the sensitivity and specificity of our method. Our study demonstrates that the combination of WBL and qPCR genotyping can serve as a high-throughput and robust approach for routine clinical SNP genotyping.