Inhibitory effect of ketoconazole on the pharmacokinetics of a multireceptor tyrosine kinase inhibitor BMS-690514 in healthy participants: assessing the mechanism of the interaction with physiologically-based pharmacokinetic simulations

BMS-690514, a selective inhibitor of the ErbB and vascular endothelial growth factor receptors, has shown antitumor activity in early clinical development. The compound is metabolized by multiple enzymes, with CYP3A4 responsible for the largest fraction (34%) of metabolism. It is also a substrate of P-glycoprotein (P-gp) in vitro. To assess the effect of ketoconazole on BMS-690514 pharmacokinetics, 17 healthy volunteers received 200 mg BMS-690514 alone followed by 100 mg BMS-690514 with ketoconazole (400 mg once daily for 4 days). The AUC(∞) of 100 mg BMS-690514 concomitantly administered with ketoconazole was similar to that of 200 mg BMS-690514 alone. The dose-normalized C(max) and AUC(∞) of BMS-690514 from the 100-mg BMS-690514/400-mg ketoconazole treatment increased by 55% and 127%, respectively, relative to those from 200 mg BMS-690514 alone. Prediction of the drug-drug interaction (DDI) using a population-based simulator (Simcyp) indicated that, in addition to CYP3A4 inhibition, the inhibition of P-gp by ketoconazole in the intestine, liver, and kidneys must be invoked to fully account for the DDI observed. This finding suggests that the inhibition of P-gp by ketoconazole, along with its effect on CYP3A4, needs to be considered when designing a DDI study of ketoconazole with a victim drug that is a dual substrate.

In-vitro growth inhibition of chemotherapy and molecular targeted agents in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common and challenging malignant disease. The prognosis is poor in patients with advanced disease. Although sorafenib prolongs survival in these patients, improvement remains modest. We used doxorubicin and sorafenib as controls and screened eight new agents including ixabepilone, gefitinib, cetuximab, brivanib, dasatinib, sunitinib, BMS-690514, and BMS-536924 against nine HCC cell lines and evaluated their interactions. We studied growth inhibition of 10 drugs against nine HCC cell lines. Single-agent activity was tested using an MTS assay. Combination studies were carried out in both resistant and sensitive cells to determine the combination index. The IC50 of each agent varied widely among nine cell lines. Ixabepilone was more potent than doxorubicin. HT-17 cells were more sensitive to gefitinib and cetuximab than the other eight cell lines. BMS-536924 showed good efficacy (IC50 ≤ 1 µmol/l) on all three α-fetoprotein (AFP)-producing cell lines (HepG2, Hep3B, Huh-7). Three cell lines showed moderate sensitivity to dasatinib (IC50 ≤ 1 µmol/l). Dasatinib showed the most frequent and strongest synergism with ixabepilone, gefitinib, brivanib, BMS-690514, or BMS-536924. Ixabepilone, sorafenib, brivanib, dasatinib, and BMS-536924 are active against HCC cell lines. The heterogeneity of the sensitivity of each cell line emphasizes the need for individualized treatment. The sensitivity to BMS-536924 is closely associated with the production of AFP. AFP may be a biomarker predicting response to the insulin-like growth factor-1 receptor inhibitor in HCC patients. Additional studies are warranted. The synergism between dasatinib and other agents also provides future research directions to understand drug resistance and improve outcome.

Species difference in the mechanism of nonlinear pharmacokinetics of E2074, a novel sodium channel inhibitor, in rats, dogs, and monkeys

New chemical entities often exhibit nonlinear pharmacokinetics (PK) profiles in experimental animals. However, the number of studies that have focused on species differences in nonlinear PK is very limited; thus, the aim of this study was to clarify the mechanism of the nonlinear PK of E2074 (2-[(2R)-2-fluoro-3-{(3r)-[(3-fluorobenzyl)oxy]-8-azabicyclo[3.2.1]oct-8-yl}propyl]-4,5-dimethyl-2,4-dihydro-3H-1,2,4-triazol-3-one), a novel sodium channel inhibitor, in rats, dogs, and monkeys. Nonlinear PK profiles with more than dose-proportional increases of Cmax and area under the plasma concentration curve were observed in all species after oral administration. The Michaelis-Menten constant (Km) values of hepatic microsomal metabolism were 7.23 and 0.41 μM in rats and dogs in vitro, respectively, which were lower than the unbound maximum plasma concentrations after oral administration in vivo, indicating that the nonlinear PK in rats and dogs was attributable to the saturation of hepatic metabolism. However, we do not believe that the saturation of hepatic metabolism was the mechanism of nonlinearity in monkeys because of the high Km value (42.44 μM) observed in liver microsomes. Intestinal metabolism was observed in monkey intestinal microsomes but not in rats and dogs, and the nonlinear PK in monkeys was diminished by inhibition of intestinal metabolism with a concomitant oral dose of ketoconazole. These results suggest that saturation of the intestinal metabolism is the potential mechanism of nonlinearity in monkeys. P-glycoprotein was not involved in the nonlinear PK profiles in any species. In conclusion, the mechanism of the nonlinear PK of E2074 is species dependent, with the saturation of hepatic metabolism in rats and dogs and that of intestinal metabolism in monkeys being the primary cause.

Vascular endothelial growth factor (VEGF) receptors: drugs and new inhibitors

The recent launch onto the market of five VEGFR inhibitors indicates the therapeutic value of these agents and the importance of the research in the field of angiogenesis inhibitors for future oncologic therapy. In this Perspective we briefly report the inhibitors that are in clinical use, while we dedicate two wider sections to the compounds that are in clinical trials and to the new derivatives appearing in the literature. We especially consider the medicinal chemistry aspect of the topic and report the structure-activity relationship studies and the binding mode of some inhibitors as well as the biological data of the compounds discovered in the past 5 years.

Antiangiogenic therapies: is VEGF-A inhibition alone enough?

Although available targeted therapies provide some clinical efficacy, a need remains for antiangiogenic therapies with alternative mechanisms in order to provide better outcomes and the ability to circumvent resistance. Inhibition of multiple VEGF targets may produce enhanced efficacy and more durable responses through synergistic effects, and prevent the development of escape mechanisms. Inhibition of VEGF-A, VEGF-C and VEGF-D with broad-spectrum VEGF receptor-2 (VEGFR-2) inhibitors, such as the novel protein therapeutic CT-322, may result in increased efficacy and prevent or delay acquired resistance and metastatic spread often seen with VEGF-A inhibition alone. Therefore, panoramic inhibition of VEGFR-2 may be a better approach to more effective antiangiogenic therapy. This article focuses on pivotal data on VEGF/VEGFR inhibitors currently in use, as well as newer agents in development.

In vitro characterization of the metabolic pathways and cytochrome P450 inhibition and induction potential of BMS-690514, an ErbB/vascular endothelial growth factor receptor inhibitor

(3R,4R)-4-Amino-1-((4-((3-methoxyphenyl)amino)pyrrolo[2,1-f][1,2,4]triazin-5-yl)methyl)-3-piperidinol (BMS-690514) is a potent inhibitor of ErbB human epidermal growth factor receptors (HER1, 2, and 4) and vascular endothelial growth factor receptors 1 to 3 that has been under clinical development for solid tumor malignancies. BMS-690514 is primarily cleared by metabolism with the primary metabolic pathways being direct glucuronidation (M6), hydroxylation (M1, M2, and M37), and O-demethylation (M3). In the current investigation, the metabolic drug-drug interaction potential of BMS-690514 was evaluated in a series of in vitro studies. Reaction phenotyping experiments with cDNA-expressed human cytochrome P450 (P450) and UDP-glucuronosyltransferase (UGT) enzymes and human liver microsomes (HLM) in the presence of P450 or UGT inhibitors suggested that CYP3A4, CYP2D6, and CYP2C9 were the major enzymes responsible for the oxidative metabolism of BMS-690514, whereas both UGT2B4 and UGT2B7 were responsible for the formation of M6. BMS-690514 did not cause direct or time-dependent inhibition of P450 enzymes (IC(50) values ≥40 μM) in incubations with HLM and probe substrates of CYP1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, or 3A4. The compound also did not substantially induce CYP1A1, CYP1A2, CYP2B6, CYP3A4, or UGT1A1 at concentrations up to 10 μM in cultured human hepatocytes. Considering the submicromolar plasma C(max) concentration at the anticipated clinical dose of 200 mg, BMS-690514 is unlikely to cause clinically relevant drug-drug interactions when coadministered with other medications. In addition, because multiple enzymatic clearance pathways are available for the compound, inhibition of an individual metabolic pathway either via coadministered drugs or gene polymorphisms is not expected to cause pronounced (>2-fold) increases in BMS-690514 exposure.