Cytochrome P4501A Induction Research Articles

Overview of Drug-Drug Interactions Between Ritonavir-Boosted Nirmatrelvir (Paxlovid) and Targeted Therapy and Supportive Care for Lung Cancer

IntroductionOral administration of ritonavir-boosted nirmatrelvir (Paxlovid) was found to be promising in the treatment of coronavirus disease 2019. The active antiviral component nirmatrelvir in Paxlovid is co-formulated with ritonavir, a strong cytochrome P450 (CYP) 3A4 inhibitor. Many oral targeted therapies indicated for lung cancer are known substrates of CYP 3A4, and concurrent use with Paxlovid may lead to potential drug-drug interaction (DDI). The purpose of this review is to evaluate the potential DDI between targeted therapies and supportive care for lung cancer and ritonavir-boosted nirmatrelvir. MethodsDrug database search in PubMed and the Food and Drug Administration was conducted to identify pharmacokinetic data on oral tyrosine kinase inhibitors (TKIs) used in NSCLC, both Food and Drug Administration approved and those in development. Metabolism pathways for various TKIs are extracted, and the impact of TKI area under the curves and maximum concentration by strong CYP 3A4 inducers and inhibitors is summarized. The most common toxicities and supportive care medications for the TKI were identified. ResultsAmong EGFR and exon 20 insertion inhibitors, afatinib is least likely to be affected by CYP 3A4, followed by dacomitinib and osimertinib. Among ALK inhibitors, alectinib is the least susceptible to CYP 3A4. ROS1 inhibitors are affected by CYP 3A4 inhibition with the exception of crizotinib. Among MET inhibitors, capmatinib is substantially affected by CYP 3A4 inhibition. Drug exposure of RET inhibitors is expected to increase with CYP 3A4 inhibition, with selpercatinib being the least affected. Certain supportive care medications for lung cancer TKI may have relevant DDIs. ConclusionsThe clinical impact of the DDI between lung cancer TKI and ritonavir-boosted nirmatrelvir varies largely on the basis of the susceptibility of CYP 3A4 inhibition caused by the antiviral. Close monitoring and medication adjustments (i.e., dose changes or alternative coronavirus disease 2019 therapy) can be used to overcome DDI to ensure patient safety.

Quantitative Cytochrome P450 3A4 Induction Risk Assessment Using Human Hepatocytes Complemented with Pregnane X Receptor-Activating Profiles.

Reliable in vitro to in vivo translation of cytochrome P450 (CYP) 3A4 induction potential is essential to support risk mitigation for compounds during pharmaceutical discovery and development. In this study, a linear correlation of CYP3A4 mRNA induction potential in human hepatocytes with the respective pregnane-X receptor (PXR) activation in a reporter gene assay using DPX2 cells was successfully demonstrated for 13 clinically used drugs. Based on this correlation, using rifampicin as a positive control, the magnitude of CYP3A4 mRNA induction for 71 internal compounds at several concentrations up to 10 µM (n = 90) was predicted within 2-fold error for 64% of cases with only a few false positives (19%). Furthermore, the in vivo area under the curve reduction of probe CYP substrates was reasonably predicted for eight marketed drugs (carbamazepine, dexamethasone, enzalutamide, nevirapine, phenobarbital, phenytoin, rifampicin, and rufinamide) using the static net effect model using both the PXR activation and CYP3A4 mRNA induction data. The liver exit concentrations were used for the model in place of the inlet concentrations to avoid false positive predictions and the concentration achieving twofold induction (F2) was used to compensate for the lack of full induction kinetics due to cytotoxicity and solubility limitations in vitro. These findings can complement the currently available induction risk mitigation strategy and potentially influence the drug interaction modeling work conducted at clinical stages. SIGNIFICANCE STATEMENT: The established correlation of CYP3A4 mRNA in human hepatocytes to PXR activation provides a clear cut-off to identify a compound showing an in vitro induction risk, complementing current regulatory guidance. Also, the demonstrated in vitro-in vivo translation of induction data strongly supports a clinical development program although limitations remain for drug candidates showing complex disposition pathways, such as involvement of auto-inhibition/induction, active transport and high protein binding.

Drug–drug interaction between dexamethasone and direct-acting oral anticoagulants: a nested case–control study in the National COVID Cohort Collaborative (N3C)

ObjectiveThe goal of this work is to evaluate if there is an increase in the risk of thromboembolic events (TEEs) due to concomitant exposure to dexamethasone and apixaban or rivaroxaban....

Availability and effects of n-TiO2 and PCB77 in fish in vitro models of the intestinal barrier and liver under single- and/or co-exposure scenarios

Titanium dioxide nanoparticles (n-TiO2) and polychlorinated biphenyls (PCBs) can be present in the food of fish, leading to intestinal exposure uptake, and accumulation in inner organs. This study examined combination effects of n-TiO2 and PCB77 in vitro models of the fish intestinal epithelium and liver, i.e., RTgut-GC cell cultures grown in ThinCerts™ and RTL-W1 cell cultures grown in standard tissue culture plates. Mass spectrometry and microscopy techniques were used to obtain information on nanoparticle translocation across the intestinal barrier model. In addition, the substances’ effect on intestinal barrier permeability, cell viability, expression of dioxin – and antioxidant response element -controlled genes, and induction of cytochrome P450 1a (Cyp1a)-dependent ethoxyresorufin-O-deethylase (EROD) activity were assessed. TiO2 nanoparticles were taken up by RTgut-GC cells and detected in the bottom compartment of the intestinal epithelial barrier model. It was not possible to conclude definitively if n-TiO2 translocation occurred via transcytosis or paracellular migration but observations of nanoparticles in the lateral space between adjacent epithelial cells were rare. PCB77 (1 and 10 µM, 24 h) did not affect barrier permeability, i.e., n-TiO2 translocation is probably not facilitated in case of co-exposure. Furthermore, previous and simultaneous exposure to n-TiO2 (1 and 10 mg/L, 24 h) did not have any influence on PCB77-induced Cyp1a mRNA and enzyme activity levels in RTL-W1 cells. Furthermore, there were no significant differences in expression of antioxidant response element-controlled genes comparing control, single substance, and mixture treatments, not even following long-term exposure (0.01–1 mg/L n-TiO2 + 1 nM PCB77, 4 weeks). While an underestimation of the effects of n-TiO2 and PCB77 cannot be fully excluded as concentration losses due to sorption to cell culture plastics were not measured, the results suggest that the test substances probably have a low potential to exhibit combination effects on the assessed endpoints when co-existing in fish tissues.

The effect of rifampin on the pharmacokinetics of famitinib in healthy subjects

BackgroundFamitinib is an oral, small-molecule, multi-targeted tyrosine kinase inhibitor under clinical investigation for the treatment of solid tumors. As famitinib is metabolized mainly by cytochrome P450 3A4 (CYP3A4), the study was conducted to investigate the effect of potent CYP3A4 inducer rifampin on the pharmacokinetics of famitinb.MethodsThis single-center, single-arm and fixed-sequence drug–drug interaction study enrolled 21healthy Chinese male subjects. Subjects received a single oral dose of famitinib 25 mg on days 1 and 16 and repeated administration of oral rifampin 600 mg once daily on days 10–23. Blood samples were collected and plasma concentrations of famitinib were measured by validated liquid chromatography-tandem mass spectrometry (LC–MS/MS) method. Pharmacokinetic parameters were calculated using noncompartmental analysis and safety was assessed.ResultsIn the presence of rifampin, the famitinib geometric mean maximum plasma concentration (Cmax) and area under the plasma concentration–time curve from time zero to infinity (AUC0–∞) decreased by 48% and 69%, respectively, and the mean elimination half-life was shortened from 33.9 to 18.2 h. The geometric mean ratio (GMR) of famitinib Cmax and AUC0–∞ and their 90% CI were 0.52 (0.50, 0.54) and 0.31 (0.29, 0.33). Single dose of famitinib 25 mg was well tolerated and eight subjects (38.1%) reported treatment emergent adverse events, which were all grade 1–2 in severity.ConclusionCo-administration of rifampin considerably reduces plasma concentration of famitinb due to CYP3A4 induction. Concomitant administration of famitinib and strong CYP3A4 inducers should be avoided, whereas when simultaneous use with inducers of CYP3A4, dose adjustment of famitinb is recommended.Clinical trial registration numberNCT04494659 (July 31, 2020).

605P Population pharmacokinetic (PK) analysis of mirvetuximab soravtansine (MIRV) in patients with folate receptor α (FRα)-positive cancer

MIRV is a first-in-class antibody-drug conjugate comprising an FRα-binding antibody, cleavable linker, and maytansinoid DM4 payload for patients (pts) with FRα-positive, high grade serious ovarian cancer (OC). Analysis was conducted across 3 studies to understand the impact of pt characteristics on the PK parameters of MIRV, DM4, and S-methyl-DM4 (SmDM4) metabolite in pts with FRα-positive tumors. A base model was developed for MIRV followed by a stepwise covariate search. Structural components were added for DM4 and SmDM4 concentration data while fixing MIRV PK parameters. The final semi-mechanistic model accommodated saturable elimination of MIRV and the payload metabolite. Model construction was based on 2 studies (n=445) with extensive sampling and validated in a 3rd study (n=98) with sparse sampling. The evaluated doses ranged from 0.15 mg/kg to 7 mg/kg total body weight, including the final recommended dose of 6 mg/kg adjusted ideal body weight (AIBW) every 3 weeks, which was administered to 87.8% of total pts. The population PK model predicted a low clearance (CL), small volume of distribution (Vd), and long elimination half-life (t1/2) for MIRV. Statistically significant covariates include AIBW, serum albumin, and age. Tumor FRα expression was not a significant covariate. AIBW showed an impact on CL and Vd. Albumin showed significant effect on CL but not on Vd. Age did not impact CL and was found to be a minor covariate on Vd. For 6 mg/kg AIBW, the effects of these covariates on the exposures to MIRV do not require dose adjustment. With a terminal elimination t1/2 of 115 hrs (4.8 days), the steady state can be reached in ∼24 days. Mild or moderate renal impairment and mild hepatic impairment did not significantly alter PK. Coadministration with weak, moderate, and strong cytochrome P450 3A4 (CYP3A4) inhibitors did not have clinically meaningful effects on PK parameters for MIRV, DM4, or SmDM4; CYP3A4 inducers were not evaluated. Population PK analysis supports 6 mg/kg AIBW dosing of MIRV, with exposure to MIRV, DM4, and SmDM4 maintained within the target range. Dosing adjustments would not be required for mild or moderate renal or mild hepatic impaired population.

Establishment and Characterization of Novel Human Intestinal In Vitro Models for Absorption and First-Pass Metabolism Studies.

Commonly used intestinal in vitro models are limited in their potential to predict oral drug absorption. They either lack the capability to form a tight cellular monolayer mimicking the intestinal epithelial barrier or the expression of cytochrome P450 3A4 (CYP3A4). The aim of this study was to establish a platform of colorectal cancer patient-derived cell lines for evaluation of human intestinal drug absorption and metabolism. We characterized ten 2D cell lines out of our collection with confluent outgrowth and long-lasting barrier forming potential as well as suitability for high throughput applications with special emphasis on expression and inducibility of CYP3A4. By assessment of the transepithelial electrical resistance (TEER) the cells barrier function capacity can be quantified. Very high TEER levels were detected for HROC60. A high basal CYP3A4 expression and function was found for HROC32. Eight cell lines showed higher CYP3A4 induction by stimulation via the vitamin D receptor compared to Caco-2 cells (5.1- to 16.8-fold change). Stimulation of the pregnane X receptor led to higher CYP3A4 induction in two cell lines. In sum, we identified the two cell lines HROC183 T0 M2 and HROC217 T1 M2 as useful tools for in vitro drug absorption studies. Due to their high TEER values and inducibility by drug receptor ligands, they may be superior to Caco-2 cells to analyze oral drug absorption and intestinal drug–drug interactions. Significance statement: Selecting appropriate candidates is important in preclinical drug development. Therefore, cell models to predict absorption from the human intestine are of the utmost importance. This study revealed that the human cell lines HROC183 T0 M2 and HROC217 T1 M2 may be better suited models and possess higher predictive power of pregnane X receptor- and vitamin D-mediated drug metabolism than Caco-2 cells. Consequently, they represent useful tools for predicting intestinal absorption and simultaneously enable assessment of membrane permeability and first-pass metabolism.

Homeostatic regulation of the aryl hydrocarbon receptor-cytochrome P450 1a axis by Scutellaria baicalensis-Coptis chinensis herb pair and its main constituents

Ethnopharmacological relevanceScutellaria baicalensis (SB) and Coptis chinensis (CC) are widely used traditional Chinese medicine (TCM) for “heat-clearing and damp-drying” and “purging fire and detoxifying”. SB-CC are commonly used as a herbal pair for synergistic treatment of various diseases such as bacteria-related infections, metabolic syndromes, and some inflammatory disorders. This herbal pair is commonly used in many famous TCM formula, like Huang-Lian-Jie-Du, Gegen-Qinlian, Banxia Xiexin decoction. Aryl hydrocarbon receptor (AHR) plays an essential role in the disposition of both xenobiotics and endogenous substances through the induction of cytochrome P450 1A (CYP1A) enzymes. Regulation of the AHR-CYP1A axis is increasingly implicated in drug-drug and drug-herb interactions. Research on SB-CC for regulatory effect on the AHR-CYP1A axis is only limited to few compounds. Aim of the studyThis study aimed to systematically investigate the regulatory effect of SB-CC and its main constitutes on the AHR-CYP1A axis in vitro and in vivo. Materials and methodsThe livers of mice treated with SB-CC extract were subjected to RNA-sequencing (RNA-seq). The key target genes related to drug metabolism were screened, and the differential expression genes (DEGs) were validated by qRT-PCR, Western blot, and enzyme activity assay. Luciferase reporter gene, qRT-PCR, and Western blot assays were used to determine whether SB-CC and their main constituents could activate AHR and regulate CYP1A expression in HepG2 cells. The effect of SB-CC on the pharmacokinetics of phenacetin, a CYP1A substrate, were further observed in mice to test the net effect of SB-CC on CYP1A functions. The potential CYP1A inhibitors in SB-CC were screened and their inhibitory mechanisms were also studied using human liver microsomes. ResultsAHR and drug metabolism system, especially CYP1A1 and CYP1A2, were strongly affected in the liver of SB-CC-treated mice. These results were further validated by the findings that SB-CC increased CYP1A's mRNA, protein expression and activity in mouse liver. In HepG2 cells, SB, CC, baicalin, baicalein, chrysin, oroxylin A, berberine, coptisine and epiberberine increased CYP1A1 mRNA expression in an AHR-dependent way. Interestingly, SB-CC treatment for 14 days only slightly increased the systemic exposure of paracetamol in mice. In the CYP1A inhibition assay, SB, CC, baicalin, baicalein, wogonoside, wogonin, chrysin, oroxylin A, scutellarein, columbamine, coptisine, palmatine, epiberberine, and berberrubine inhibited CYP1A activity in different degree. ConclusionsThese results suggested that SB-CC exerted dual regulatory effect on the AHR-CYP1A axis by increasing CYP1A expression but simultaneously inhibiting CYP1A activity, which may contribute to a tight modulation of AHR signaling for homeostatic control.

Rifampin Drug-Drug-Interaction Studies: Reflections on the Nitrosamine Impurities Issue.

Clinical development of new drugs may require dedicated drug-drug interaction (DDI) studies, such as to evaluate the effect of cytochrome P450 3A induction on the pharmacokinetics of investigational drugs. However, as a result of N-nitrosamine impurity findings in marketed rifampin formulations, the application of rifampin in DDI studies has been halted. This mini-review considers the root cause and impact of the nitrosamine impurity as well as alternative options for the continued conduct of DDIs.

Organoid-derived intestinal epithelial cells are a suitable model for preclinical toxicology and pharmacokinetic studies

SummaryIntestinal organoids are physiologically relevant tools used for cellular models. However, the suitability of organoids to examine biological functions over existing established cell lines lacks sufficient evidence. Cytochrome P450 3A4 (CYP3A4) induction by pregnane X receptor ligands, glucose uptake via sodium/glucose cotransporter 1, and microsomal triglyceride transfer protein-dependent ApoB-48 secretion, which are critical for human intestinal metabolism, were observed in organoid-derived two-dimensional cells but little in Caco-2 cells. CYP3A4 induction evaluation involved a simplified method of establishing organoids that constitutively expressed a reporter gene. Compound screening identified several anticancer drugs with selective activities toward Caco-2 cells, highlighting their characteristics as cancer cells. Another compound screening revealed a decline in N-(4-hydroxyphenyl)retinamide cytotoxicity upon rifampicin treatment in organoid-derived cells, under CYP3A4-induced conditions. This study shows that organoid-derived intestinal epithelial cells (IECs) possess similar physiological properties as intestinal epithelium and can serve as tools for enhancing the prediction of biological activity in humans.

Tutorial: Statistical analysis and reporting of clinical pharmacokinetic studies.

Pharmacokinetics is the cornerstone of understanding drug absorption, distribution, metabolism, and elimination. It is also the key to describing variability in drug response caused by drug‐drug interactions (DDIs), pharmacogenetics, impaired kidney and liver function, etc. This tutorial aims to provide a guideline and step‐by‐step tutorial on essential considerations when designing clinical pharmacokinetic studies and reporting results. This includes a comprehensive guide on how to conduct the statistical analysis and a complete code for the statistical software R. As an example, we created a mock dataset simulating a clinical pharmacokinetic DDI study with 12 subjects who were administered 2 mg oral midazolam with and without an inducer of cytochrome P450 3A. We provide a step‐by‐step guide to the statistical analysis of this clinical pharmacokinetic study, including sample size/power calculation, descriptive statistics, noncompartmental analyses, and hypothesis testing. The different analyses and parameters are described in detail, and we provide a complete R code ready to use in supplementary files. Finally, we discuss important considerations when designing and reporting clinical pharmacokinetic studies. The scope of this tutorial is not limited to DDI studies, and with minor adjustments, it applies to all types of clinical pharmacokinetic studies. This work was done by early career researchers for early career researchers. We hope this tutorial may help early career researchers when getting started on their own pharmacokinetic studies. We encourage you to use this as an inspiration and starting point and continuously evolve your statistical skills.

Sulfated Extract of Abelmoschus Esculentus: A Potential Cancer Chemo-preventive Agent.

Abelmoschus esculentus (AE) (okra), is an edible plant used in many food applications. This study explored whether sulfated AE (SAE) has promising cancer chemopreventive activities that may recommend it as a functional food supplement instead of (or in addition to) AE for the population at risk of cancer and in the health food industry. Cytochrome P450-1A (CYP1A) was estimated by fluorescence enzymatic reaction, using β-naphthoflavone-treated cells (CYP1A inducer). Peroxyl and hydroxyl radical scavenging was assayed by oxygen radical absorbance capacity assay. Flow cytometry was used to analyze apoptosis/necrosis in MCF-7 cells, cell cycle phases in MCF-7 cells, and macrophage binding to fluorescein isothiocyanate-lipopolysaccharide (FITC-LPS). Nitric oxide was determined by Griess assay in LPS-stimulated macrophages, and cytotoxicity was determined by MTT assay. Diethylnitrosamine (DEN) was used to induce hepatic tumor initiation in rats. Placental glutathione-S-transferase (GSTP; an initiation marker) was stained in a fluorescence immunohistochemical analysis of liver sections, and histopathological changes were examined. SAE exhibited strong antitumor initiation and antitumor promotion activities. It suppressed CYP1A, scavenged peroxyl and hydroxyl radicals, induced macrophage proliferation, suppressed macrophage binding to FITC-LPS, inhibited nitric oxide generation, showed specific cytotoxicity to human breast MCF-7 adenocarcinoma cells, and disturbed the cell cycle phases (S and G2/M phases) in association with an increased percentage of apoptotic/necrotic MCF-7 cells. Over a short time period, DEN stimulated liver cancer initiation, but SAE treatment reduced the DEN-induced histopathological alterations and inhibited CYP1A and GSTP. SAE extract has the potential for use as an alternative to AE in health foods to provide cancer chemoprevention in populations at risk for cancer.

Ginsenoside Rg1 protects mice against 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced liver injury by inhibiting CYP1A1 through the aryl hydrocarbon receptor

Ethnopharmacological relevancePanax ginseng C. A. Meyer (ginseng) is a widely used traditional Chinese medicine that has played a beneficial role in the treatment of various diseases, including liver diseases. Ginsenoside Rg1 is a saponin isolated and purified from ginseng that exerts protective effects on the liver in some liver injury models. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a ubiquitous dioxin found mostly in food products that causes liver injury and other human diseases. Although significant efforts have been made to reduce the burden of liver disease, there is still a lack of effective treatment methods.Aim of the study: Although ginsenoside Rg1 was reported to inhibit TCDD-mediated cytochrome P450 1A1 (CYP1A1) induction in HepG2 cells, we sought to verify its hepatoprotective effects and elucidate its mechanism in a TCDD-induced liver injury model in mice. Material and methodsThe mouse liver injury model was established by intraperitoneal TCDD injection, followed by treatment with various doses of ginsenoside Rg1 (50, 100, and 200 mg/kg). Clinical indicators of liver injury, such as an increase in serum aspartate aminotransferase and alanine aminotransferase levels, as well as histopathological changes were evaluated. ResultsThe common clinical indicators of liver injury were detected following TCDD injection, including an increase in serum alanine aminotransferase and aspartate aminotransferase levels, increased relative liver weight, and histopathological changes. Following treatment with ginsenoside Rg1, the levels of aspartate aminotransferase and alanine aminotransferase decreased significantly, and the liver histology was improved. In addition, ginsenoside Rg1 competitively inhibited TCDD-induced Cyp1a1 mRNA transcription through the modulation of aryl hydrocarbon receptor (AhR) nuclear translocation. ConclusionGinsenoside Rg1 is a potent partial AhR agonist that has potential as an effective medication for protecting against TCDD-associated liver injury.

Characterization of Correction Factors to Enable Assessment of Clinical Risk from In Vitro CYP3A4 Induction Data and Basic Drug-Drug Interaction Models.

Background and ObjectiveInduction of drug-metabolizing enzymes can lead to drug-drug interactions (DDIs); therefore, early assessment is often conducted. Previous reports focused on true positive cytochrome P450 3A (CYP3A) inducers leaving a gap in translation for in vitro inducers which do not manifest in clinical induction. The goal herein was to expand the in vitro induction dataset by including true negative clinical inducers to identify a correction factor to basic DDI models, which reduces false positives without impacting false negatives.MethodsTrue negative clinical inducers were identified through a literature search, in vitro induction parameters were generated in three human hepatocyte donors, and the performance of basic induction models proposed by regulatory agencies, concentration producing twofold induction (F2), basic static model (R3) and relative induction score (RIS), was used to characterize clinical induction risk.ResultsThe data demonstrated the importance of correcting for in vitro binding and metabolism to derive induction parameters. The aggregate analysis indicates that the RIS with a positive cut-off of < 0.7-fold area under the curve ratio (AUCR) provides the best quantitative prediction. Additionally, correction factors of ten and two times the unbound peak plasma concentration at steady state (Cmax,ss,u) can be confidently used to identify true positive inducers when referenced against the concentration resulting in twofold increase in messenger ribonucleic acid (mRNA) or using the R3 equation, respectively.ConclusionsThese iterative improvements, which reduce the number of false positives, could aid regulatory recommendations and limit unnecessary clinical explorations into CYP3A induction.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s13318-022-00763-y.

Puromycin-based purification of cells with high expression of the cytochrome P450 CYP3A4 gene from a patient with drug-induced liver injury (DILI)

BackgroundMany drugs have the potential to induce the expression of drug-metabolizing enzymes, particularly cytochrome P450 3A4 (CYP3A4), in hepatocytes. Hepatocytes can be accurately evaluated for drug-mediated CYP3A4 induction; this is the gold standard for in vitro hepatic toxicology testing. However, the variation from lot to lot is an issue that needs to be addressed. Only a limited number of immortalized hepatocyte cell lines have been reported. In this study, immortalized cells expressing CYP3A4 were generated from a patient with drug-induced liver injury (DILI).MethodsTo generate DILI-derived cells with high expression of CYP3A4, a three-step approach was employed: (1) Differentiation of DILI-induced pluripotent stem cells (DILI-iPSCs); (2) Immortalization of the differentiated cells; (3) Selection of the cells by puromycin. It was hypothesized that cells with high cytochrome P450 gene expression would be able to survive exposure to cytotoxic antibiotics because of their increased drug-metabolizing activity. Puromycin, a cytotoxic antibiotic, was used in this study because of its rapid cytocidal effect at low concentrations.ResultsThe hepatocyte-like cells differentiated from DILI-iPSCs were purified by exposure to puromycin. The puromycin-selected cells (HepaSM or SI cells) constitutively expressed the CYP3A4 gene at extremely high levels and exhibited hepatocytic features over time. However, unlike primary hepatocytes, the established cells did not produce bile or accumulate glycogen.ConclusionsiPSC-derived hepatocyte-like cells with intrinsic drug-metabolizing enzymes can be purified from non-hepatocytes and undifferentiated iPSCs using the cytocidal antibiotic puromycin. The puromycin-selected hepatocyte-like cells exhibited characteristics of hepatocytes after immortalization and may serve as another useful source for in vitro hepatotoxicity testing of low molecular weight drugs.

Dexamethasone is a dose-dependent perpetrator of drug-drug interactions: implications for use in people living with HIV.

Global use of dexamethasone in COVID-19 patients has revealed a poor understanding of the drug–drug interaction (DDI) potential of dexamethasone, particularly with antiretroviral agents (ARVs). Dexamethasone is both a substrate and a dose-dependent inducer of cytochrome P450 3A4 (CYP3A4). As many ARVs are substrates and/or inhibitors or inducers of CYP3A4, there is concern about DDIs with dexamethasone either as a perpetrator or a victim. Assessment of DDIs that involve dexamethasone is complex as dexamethasone is used at a range of daily doses (generally 0.5 up to 40 mg) and a treatment course can be short, long, or intermittent. Moreover, DDIs with dexamethasone have been evaluated only for a limited number of drugs. Here, we summarize the available in vitro and in vivo data on the interaction potential of dexamethasone and provide recommendations for the management of DDIs with ARVs, considering various dexamethasone dosages and treatment durations.

Unraveling pleiotropic effects of rifampicin by using physiologically based pharmacokinetic modeling: Assessing the induction magnitude of P-glycoprotein-cytochrome P450 3A4 dual substrates.

Rifampicin induces both P‐glycoprotein (P‐gp) and cytochrome P450 3A4 (CYP3A4) through regulating common nuclear receptors (e.g., pregnane X receptor). The interplay of P‐gp and CYP3A4 has emerged to be an important factor in clinical drug–drug interactions (DDIs) with P‐gp–CYP3A4 dual substrates and requires qualitative and quantitative understanding. Although physiologically based pharmacokinetic (PBPK) modeling has become a widely accepted approach to assess DDIs and is able to reasonably predict DDIs caused by CYP3A4 induction and P‐gp induction individually, the predictability of PBPK models for the effect of simultaneous P‐gp and CYP3A4 induction on P‐gp‐CYP3A4 dual substrates remains to be systematically evaluated. In this study, we used a PBPK modeling approach for the assessment of DDIs between rifampicin and 12 drugs: three sensitive P‐gp substrates, seven P‐gp–CYP3A4 dual substrates, and two P‐gp–CYP3A4 dual substrates and inhibitors. A 3.5‐fold increase of intestinal P‐gp abundance was incorporated in the PBPK models to account for rifampicin‐mediated P‐gp induction at steady state. The simulation results showed that accounting for P‐gp induction in addition to CYP3A4 induction improved the prediction accuracy of the area under the concentration‐time curve and maximum (peak) plasma drug concentration ratios compared with considering CYP3A4 induction alone. Furthermore, the interplay of relevant drug‐specific parameters and its impact on the magnitude of DDIs were evaluated using sensitivity analysis. The PBPK approach described herein, in conjunction with robust in vitro and clinical data, can help in the prospective assessment of DDIs involving other P‐gp and CYP3A4 dual substrates. The database reported in the present study provides a valuable aid in understanding the combined effect of P‐gp and CYP3A4 induction during drug development.

Drug Interactions Involving 17α-Ethinylestradiol: Considerations Beyond Cytochrome P450 3A Induction and Inhibition.

It is widely acknowledged that drug-drug interactions (DDIs) involving estrogen (17α-ethinylestradiol (EE))-containing oral contraceptives (OCs) are important. Consequently, sponsors of new molecular entities (NMEs) often conduct clinical studies with priority given to OCs as victims of cytochrome P450 (CYP) 3A (CYP3A) induction and inhibition. Such scenarios are reflected in the US Food and Drug Administration-issued guidance documentation related to OC DDI studies. Although CYP3A is important, OCs such as EE are metabolized by sulfotransferase 1E1 and UDP-glucuronosyltransferase (UGT) 1A1, expressed in the gut and liver, and so both can also serve as loci of victim OC DDI. Therefore, for any NME, one should carefully consider its induction and inhibition profile involving CYP3A4/5, UGT1A1, and SULT1E1. As DDI perpetrators, available clinical DDI data indicate that EE-containing OCs can induce (e.g., UGT1A4 and CYP2A6) and inhibit (CYP1A2 ≥ CYP2C19 > CYP3A4/5 > CYP2C8, CYP2B6, CYP2D6, and CYP2C9) various CYP forms. Although available in vitro CYP inhibition data do not explain such a graded inhibitory effect in vivo, it is hypothesized that EE differentially modulates CYP expression via potent agonism of the estrogen receptor expressed in the gut and liver. From the standpoint of the NME as potential OC DDI victim, therefore, it is important to assess its projected (pre-phase I) or known therapeutic index and pharmacokinetic profile (fraction absorbed, absolute oral bioavailability, clearance/extraction class, fraction metabolized by CYP1A2, CYP2C19, CYP2A6, and UGT1A4). Such information can enable the prioritization, design, and interpretation of NME-OC DDI studies.

Effects of benzo[a]pyrene exposure on black rockfish (Sebastes schlegelii): EROD activity, CYP1A protein, and immunohistochemical and histopathological alterations.

Cytochrome P450 1A (CYP1A) is the major phase I of metabolic enzyme that plays essential roles in the detoxification of drugs and biotransformation of environmental pollutants. This study investigated CYP1A enzyme induction using EROD activity, CYP1A protein levels, and immunohistochemistry, along with histopathology of the liver, gills, kidneys, and intestine from the black rockfish, Sebastes schlegelii, exposed to benzo[a]pyrene (B[a]P). S. schlegelii has high risks of ingestion of sediment and absorption of heavy crude oil after accidental oil spills in Korea. This study thus exposed fish to B[a]P at 2, 20, and 200 μg/g body weight. EROD activity and CYP1A protein levels in hepatic microsomes had a positive correlation with the concentration of B[a]P (2-200 μg/g); in particular, exposure to 200 μg/g of B[a]P resulted in a 4- and 6-fold increase in hepatic EROD activity and CYP1A protein level, respectively. Hyperplasia of primary lamellar epithelium and atrophy of renal tubules were observed in the gills and kidney, respectively, following exposure to B[a]P at 200 μg/g. In contrast, severe histological alteration was not seen in intestinal tissues. Immunohistochemical analysis of the distribution of cellular CYP1A in four tissues showed strong immunostaining in the cytoplasm and nuclear membranes of the liver against B[a]P at 200 μg/g. Polycyclic aromatic hydrocarbons (PAHs), such as B[a]P, cause adverse histological changes in tissues of fish and provide evidence that PAH metabolism is inducible in fish liver, leading to increased CYP1A induction. Furthermore, the CYP1A induction in specific tissues might assist in monitoring and field assessment of marine ecosystems.

Abstract CT125: Evaluation of potential drug-drug interactions (DDIs) between futibatinib and CYP3A inhibitors/inducers, CYP3A substrates, or proton pump inhibitors (PPIs)

Abstract Background Futibatinib is an oral, irreversible FGFR1-4 inhibitor with clinical activity in cholangiocarcinoma and other FGFR-aberrant tumors. The recommended futibatinib dosage is 20 mg once daily (QD). In vitro studies have shown that futibatinib is predominantly metabolized by and inhibits cytochrome p450 3A (CYP3A); futibatinib is also a P-glycoprotein substrate. Two phase 1 studies were performed in healthy volunteers to evaluate potential DDIs between futibatinib and CYP3A substrates (midazolam; study 1) or CYP3A inhibitors/inducers (itraconazole/rifampin; study 2). As the solubility of futibatinib is pH dependent, study 3 assessed the effect of PPI (lansoprazole) coadministration on futibatinib pharmacokinetics (PK). Methods All 3 studies, conducted in adult nonsmokers, were open-label, fixed-sequence, 2-period cross-over studies with a 1- or 2-d washout between each period. In study 1, midazolam 2 mg was given on d1 of period 1 (-futibatinib) and on d7 of period 2 (+futibatinib 20 mg QD d1-7). In study 2, futibatinib 20 mg was given on d1 of period 1 (alone) and on d5 (+itraconazole 200 mg QD d1-6) or d8 (+rifampin 600 mg QD d1-9) of period 2. In study 3, futibatinib 20 mg was given on d1 of period 1 (-lansoprazole) and d5 of period 2 (+lansoprazole 60 mg QD d1-5). Plasma samples for PK assessment were collected predose through 24 h post-midazolam dosing (study 1) and predose through 48 h post-futibatinib dosing (studies 2 and 3). Results In study 1 (N=24), coadministration of futibatinib did not result in clinically significant changes in midazolam PK, based on the area under the concentration curve extrapolated to the last measurable time (AUC0-t; -9%) or infinity (AUC0-inf; -9%) or maximum plasma concentration (Cmax; -5%), compared with midazolam alone. In study 2 (N=40), relative to futibatinib administered alone, coadministration with itraconazole increased futibatinib Cmax (+51%) and plasma exposure (AUC0-t and AUC0-inf +41% each), whereas coadministration with rifampin decreased futibatinib Cmax (-53%) and plasma exposure (AUC0-t and AUC0-inf -64% each). In study 3 (N=20), coadministration of lansoprazole did not result in clinically significant changes in futibatinib PK parameters vs futibatinib alone (AUC0-t +5%; AUC0-inf +5%; Cmax +8%). Agents were well tolerated, and all 3 studies were completed with no clinically relevant safety signals. Conclusions Futibatinib is not expected to affect the exposure of concomitant medications metabolized via CYP3A, the most common drug metabolism pathway. Caution should be exercised when coadministering strong CYP3A inducers or inhibitors with futibatinib, as significant DDIs were observed with itraconazole and rifampin. Futibatinib can be concomitantly administered with PPIs with no clinically relevant impact on futibatinib exposure. Citation Format: Ikuo Yamamiya, John Laabs, Allen Hunt, Toru Takenaka, Daryl Sonnichsen, Mark Mina, Yaohua He, Karim Benhadji. Evaluation of potential drug-drug interactions (DDIs) between futibatinib and CYP3A inhibitors/inducers, CYP3A substrates, or proton pump inhibitors (PPIs) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT125.