Effects of Food, Gastric Acid Reduction, and Strong CYP3A Induction on the Pharmacokinetics of Tasurgratinib, a Novel Selective Fibroblast Growth Factor Receptor Inhibitor.

We conducted this three-part study in healthy subjects to investigate the pharmacokinetics of tasurgratinib (orally available selective inhibitor of fibroblast growth factor receptor 1-3) and M2 (its major metabolite) under different conditions. In Part A, subjects received tasurgratinib 35 mg either fed with a high-fat meal or fasted. In Parts B and C, subjects received tasurgratinib 35 mg alone or with either rabeprazole (acid-reducing agent) 20 mg (Part B) or rifampin (strong CYP3A inducer) 600 mg (Part C). Primary endpoints were maximum concentration (Cmax), and areas under the plasma concentration-time curve to time of last quantifiable concentration (AUC(0-t)) and extrapolated to infinite time (AUC(0-inf)). Forty-two subjects were enrolled, 14 each into Parts A, B, and C. In Part A, administration of tasurgratinib with a high-fat meal resulted in 33% reduction in Cmax and ∼23% reduction in AUC(0-t) and AUC(0-inf) of tasurgratinib, and 47% reduction in Cmax with ∼30% reduction in AUC(0-t) and AUC(0-inf) of M2. In Part B, co-administration of rabeprazole at steady state resulted in no/weak interaction with tasurgratinib (∼8% increase in AUC(0-t) and AUC(0-inf) without an effect on Cmax) and M2 (∼18% increase in AUC(0-t) and AUC(0-inf) without an effect on Cmax). In Part C, co-administration of rifampin at steady state resulted in a weak interaction with tasurgratinib (∼16% reduction in AUC(0-t) and AUC(0-inf)) and M2 (∼12% reduction in AUC(0-t) and AUC(0-inf)). Administration of tasurgratinib with a high-fat meal appeared to reduce systemic exposure of tasurgratinib, however co-administration with an acid-reducing agent or a CYP3A inducer had a minimal impact on pharmacokinetics.

Establishment of a stable aryl hydrocarbon receptor-responsive HepG2 cell line.

The aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor. It heterodimerizes with aryl hydrocarbon nuclear translocator, binds to the xenobiotic-responsive element (XRE), and enhances the transcription of genes encoding xenobiotic metabolizing enzymes. AHR also plays important roles in the inhibition of intestinal carcinogenesis and the modulation of gut immunity. It is very important to screen for AHR-activating compounds because those are expected to produce the AHR-mediated physiological functions. Until now, AHR-mediated transcriptional activity represented by the transcriptional activity of CYP1A1 in luciferase assay has been applied as a screening procedure for AHR-activating compounds. However, the AHR-mediated transcriptional activity did not necessarily correspond with the CYP1A1 transcriptional activity. To evaluate AHR-mediated transcriptional activity more specifically, and to screen for AHR-activating compounds, we establish a stable AHR-responsive HepG2 cell line by co-transfection of an AHR expression vector and an AHR-responsive vector (pGL3-XRE) containing a luciferase gene and three tandemly arranged XRE elements into a human hepatoma derived cell line, HepG2. The induction of luciferase activity in the stable AHR-responsive HepG2 cell line by typical AHR activators occurred in time- and concentration-dependent manners. By assessing the AHR target genes CYP1A1, UGT1A1, and ABCG2, an AHR activator-mediated induction was observed at mRNA level. Furthermore, the AHR activator-mediated induction of luciferase activity was positively correlated with the mRNA levels of CYP1A1, UGT1A1, and ABCG2. These findings verified the usefulness of the established stable AHR-responsive HepG2 cell line for the screening of AHR-activating compounds.

6-shogaol, a major compound in ginger, induces aryl hydrocarbon receptor-mediated transcriptional activity and gene expression.

Xenobiotics are usually detoxified by drug-metabolizing enzymes and excreted from the body. The expression of many of drug-metabolizing enzymes is regulated by the aryl hydrocarbon receptor (AHR). Some substances in vegetables have the potential to be AHR ligands. To search for vegetable components that exhibit AHR-mediated transcriptional activity, we assessed the activity of vegetable extracts and identified the active compounds using the previously established stable AHR-responsive HepG2 cell line. Among the hot water extracts of vegetables, the highest activity was found in ginger. The ethyl acetate fraction of the ginger hot water extract remarkably induced AHR-mediated transcriptional activity, and the major active compound was found to be 6-shogaol. Subsequently, the mRNA levels of AHR-targeting drug-metabolizing enzymes (CYP1A1, UGT1A1, and ABCG 2) and the protein level of CYP1A1 in HepG2 cells were shown to be increased by 6-shogaol. This is the first report that 6-shogaol can regulate the expression of detoxification enzymes by AHR activation.