Evaluation of the Cytochrome P450 3A and P-glycoprotein Drug-Drug Interaction Potential of Futibatinib.

Futibatinib, a selective, irreversible fibroblast growth factor receptor 1-4 inhibitor, is being investigated for tumors harboring FGFR aberrations and was recently approved for the treatment of FGFR2 fusion/rearrangement-positive intrahepatic cholangiocarcinoma. In vitro studies identified cytochrome P450 (CYP) 3A as the major CYP isoform in futibatinib metabolism and indicated that futibatinib is likely a P-glycoprotein (P-gp) substrate and inhibitor. Futibatinib also showed time-dependent inhibition of CYP3A in vitro. Phase I studies investigated the drug-drug interactions of futibatinib with itraconazole (a dual P-gp and strong CYP3A inhibitor), rifampin (a dual P-gp and strong CYP3A inducer), or midazolam (a sensitive CYP3A substrate) in healthy adult participants. Compared with futibatinib alone, coadministration of futibatinib with itraconazole increased futibatinib mean peak plasma concentration and area under the plasma concentration-time curve by 51% and 41%, respectively, and coadministration of futibatinib with rifampin lowered futibatinib mean peak plasma concentration and area under the plasma concentration-time curve by 53% and 64%, respectively. Coadministration of midazolam with futibatinib had no effect on midazolam pharmacokinetics compared with midazolam administered alone. These findings suggest that concomitant use of dual P-gp and strong CYP3A inhibitors/inducers with futibatinib should be avoided, but futibatinib can be concomitantly administered with other drugs metabolized by CYP3A. Drug-drug interaction studies with P-gp-specific substrates and inhibitors are planned.

TAS4464, A Highly Potent and Selective Inhibitor of NEDD8-Activating Enzyme, Suppresses Neddylation and Shows Antitumor Activity in Diverse Cancer Models.

NEDD8-activating enzyme (NAE) is an essential E1 enzyme of the NEDD8 conjugation (neddylation) pathway, which controls cancer cell growth and survival through activation of cullin-RING ubiquitin ligase complexes (CRL). In this study, we describe the preclinical profile of a novel, highly potent, and selective NAE inhibitor, TAS4464. TAS4464 selectively inhibited NAE relative to the other E1s UAE and SAE. TAS4464 treatment inhibited cullin neddylation and subsequently induced the accumulation of CRL substrates such as CDT1, p27, and phosphorylated IκBα in human cancer cell lines. TAS4464 showed greater inhibitory effects than those of the known NAE inhibitor MLN4924 both in enzyme assay and in cells. Cytotoxicity profiling revealed that TAS4464 is highly potent with widespread antiproliferative activity not only for cancer cell lines, but also patient-derived tumor cells. TAS4464 showed prolonged target inhibition in human tumor xenograft mouse models; weekly or twice a week TAS4464 administration led to prominent antitumor activity in multiple human tumor xenograft mouse models including both hematologic and solid tumors without marked weight loss. As a conclusion, TAS4464 is the most potent and highly selective NAE inhibitor reported to date, showing superior antitumor activity with prolonged target inhibition. It is, therefore, a promising agent for the treatment of a variety of tumors including both hematologic and solid tumors. These results support the clinical evaluation of TAS4464 in hematologic and solid tumors.

Human small intestinal epithelial cells differentiated from adult intestinal stem cells as a novel system for predicting oral drug absorption in humans.

Adult intestinal stem cells (ISCs) possess both a long-term proliferation ability and differentiation capability into enterocytes. As a novel in vitro system for the evaluation of drug absorption, we characterized a human small intestinal epithelial cell (HIEC) monolayer that differentiated from adult ISCs. Continuous proliferation/differentiation from ISCs consistently conferred the capability of maturation of enterocytes to HIECs over 25 passages. The morphologically matured HIEC monolayer consisted of polarized columnar epithelia with dense microvilli, tight junctions, and desmosomes 8 days after seeding onto culture inserts. Transepithelial electrical resistance across the monolayer was 9-fold lower in HIECs (98.9 Ω × cm(2)) than in Caco-2 cells (900 Ω × cm(2)), which indicated that the looseness of the tight junctions in the HIEC monolayer was similar to that in the human small intestine (approximately 40 Ω × cm(2)). No significant differences were observed in the overall gene expression patterns of the major drug-metabolizing enzymes and transporters between the HIEC and Caco-2 cell monolayers. Furthermore, the functions of P-glycoprotein and breast cancer resistance protein in the HIEC monolayer were confirmed by the vectorial transport of marker substrates and their disappearance in the presence of specific inhibitors. The apparent drug permeability values of paracellularly transported compounds (fluorescein isothiocyanate-dextran 4000, atenolol, and terbutaline) and nucleoside transporter substrates (didanosine, ribavirin, and doxifluridine) in the HIEC monolayer were markedly higher than those of Caco-2 cells, whereas transcellularly transported drugs (pindolol and midazolam) were equally well permeated. In conclusion, the HIEC monolayer can serve as a novel and superior alternative to the conventional Caco-2 cell monolayer for predicting oral absorption in humans.

The novel VEGF receptor/MET-targeted kinase inhibitor TAS-115 has marked in vivo antitumor properties and a favorable tolerability profile.

VEGF receptor (VEGFR) signaling plays a key role in tumor angiogenesis. Although some VEGFR signal-targeted drugs have been approved for clinical use, their utility is limited by associated toxicities or resistance to such therapy. To overcome these limitations, we developed TAS-115, a novel VEGFR and hepatocyte growth factor receptor (MET)-targeted kinase inhibitor with an improved safety profile. TAS-115 inhibited the kinase activity of both VEGFR2 and MET and their signal-dependent cell growth as strongly as other known VEGFR or MET inhibitors. On the other hand, kinase selectivity of TAS-115 was more specific than that of sunitinib and TAS-115 produced relatively weak inhibition of growth (GI50 > 10 µmol/L) in VEGFR signal- or MET signal-independent cells. Furthermore, TAS-115 induced less damage in various normal cells than did other VEGFR inhibitors. These data suggest that TAS-115 is extremely selective and specific, at least in vitro. In in vivo studies, TAS-115 completely suppressed the progression of MET-inactivated tumor by blocking angiogenesis without toxicity when given every day for 6 weeks, even at a serum-saturating dose of TAS-115. The marked selectivity of TAS-115 for kinases and targeted cells was associated with improved tolerability and contributed to the ability to sustain treatment without dose reduction or a washout period. Furthermore, TAS-115 induced marked tumor shrinkage and prolonged survival in MET-amplified human cancer-bearing mice. These data suggest that TAS-115 is a unique VEGFR/MET-targeted inhibitor with improved antitumor efficacy and decreased toxicity.

Evaluation of effects of polymorphism for metabolic enzymes on pharmacokinetics of carvedilol by population pharmacokinetic analysis.

In our previous study it was observed that the frequencies of UGT1A1*6, UGT2B7*3 and CYP2D6*10 in patients who have a low level ability of glucuronidation were significantly higher than those in patients with a high level of ability of glucuronidation. The same tendency was found in the frequency of CYP2D6*5, though there was no significant difference. The purpose of this study was to evaluate the effects of the polymorphism on pharmacokinetics of carvedilol by population pharmacokinetic analysis. Population pharmacokinetic analysis was performed using 373 plasma concentrations from 41 patients with chronic heart failure or angina pectoris. A one compartment pharmacokinetic model with first-order absorption (for oral dosing) was used to describe the concentration-versus-time data for carvedilol. We examined the effects of various clinical and genetic covariables in the regression models for clearance and volume of distribution. The results suggested that the factors of interindividual variation for carvedilol clearance were creatinine clearance and polymorphisms of UGT2B7 and CYP2D6 in the Japanese population with heart disease. It was estimated that UGT2B7*3 decreased the clearance of carvedilol by 37%, but UGT2B7*2 did not show any effect. Clearance in the patients who have intermediate activity of CYP2D6 was decreased by 39%.

Contribution of polymorphisms in UDP-glucuronosyltransferase and CYP2D6 to the individual variation in disposition of carvedilol.

PURPOSE: It has been reported that carvedilol, which has beta-adrenergic blocking and vasodilating activities, is mainly metabolized by UDP-glucuronosyltransferase (UGT) 1A1, UGT2B4, UGT2B7 and CYP2D6. The aim of this study was to determine whether the activity of glucuronidation has an influence on the area under the curve (AUC) of carvedilol and whether polymorphisms in UGTs and CYP2D6 contribute to individual variation in disposition of carvedilol in Japanese. METHODS: Plasma concentrations of carvedilol and its glucuronide were determined by reversed-phase high-performance liquid chromatography (HPLC). Genotyping of UGT1A1, UGT2B4 and UGT2B7 genes was carried out by the direct sequence method. CYP2D6 genotyping was carried out using an amplification refractory mutation system (ARMS) assay and PCR-restriction fragment length polymorphism (RFLP). RESULTS: The level of carvedilol glucuronidation ability in the high-level AUC group was significantly lower than that in the low-level group. The frequencies of UGT1A1*6, UGT2B7*3 and CYP2D6*10 in the low level ability of glucuronidation group were significantly higher than those in the high level group, and the same tendency was found in the frequency of CYP2D6*5, though there was no significant difference. CONCLUSION: Polymorphisms of UGT1A1, UGT2B7 and CYP2D6 strongly affect the pharmacokinetics and disposition of carvedilol in Japanese.