A Phase 1 study of ARQ 087, an oral pan-FGFR inhibitor in patients with advanced solid tumours.

BACKGROUND: ARQ 087 is an orally administered pan-FGFR inhibitor with multi-kinase activity. This Phase 1 study evaluated safety, pharmacokinetics, and pharmacodynamics of ARQ 087 and defined the recommended Phase 2 dose (RP2D). METHODS: Patients with advanced solid tumours received ARQ 087 administered initially at 25 mg every other day and dose-escalated from 25 to 425 mg daily (QD) continuous dosing. FGF19, 21, 23, and serum phosphate were assessed as potential biomarkers of target engagement. RESULTS: 80 patients were enrolled, 61 in dose-escalation/food-effect cohorts and 19 with pre-defined tumour types in the expansion cohort. The most common ARQ 087-related adverse events were fatigue (49%), nausea (46%), aspartate aminotransferase (AST) increase (30%), and diarrhoea (23%). Four patients (5%) experienced grade 1 treatment-related hyperphosphataemia. Dose-limiting toxicity was reversible grade 3 AST increase. The RP2D was 300 mg QD. Pharmacokinetics were linear and dose-proportional from 25 to 325 mg QD, and were unaffected by food. Statistically significant changes (P-value<0.05) suggest phosphate and FGF19 levels as markers of target engagement. In 18 evaluable patients with FGFR genetic alterations, 3 confirmed partial responses (two intrahepatic cholangiocarcinomas (iCCA) with FGFR2 fusions and one urothelial cancer with FGFR2 and FGF19 amplification) and two durable stable disease at ⩾16 weeks with tumour reduction (FGFR2 fusion-positive iCCA and adrenocortical carcinoma with FGFR1 amplification) were observed. CONCLUSIONS: ARQ 087 had manageable toxicity at the RP2D of 300 mg QD, showed pharmacodynamics effects, and achieved objective responses, notably in patients with FGFR2 genetic alterations.

A Phase-1b study of tivantinib (ARQ 197) in adult patients with hepatocellular carcinoma and cirrhosis.

BACKGROUND: The mesenchymal-epithelial transition factor (MET) receptor is dysregulated in hepatocellular carcinoma (HCC), and tivantinib (ARQ 197) is an oral, selective, MET inhibitor. METHODS: This Phase-1b study assessed tivantinib safety as primary objective in patients with previously treated HCC and Child-Pugh A or B liver cirrhosis. Patients received oral tivantinib 360 mg twice daily until disease progression or unacceptable toxicity. RESULTS: Among 21 HCC patients, common drug-related adverse events (AEs) were neutropaenia, anaemia, asthenia, leucopaenia, anorexia, diarrhoea, and fatigue. No drug-related worsening of liver function or performance status occurred, but one Child-Pugh B patient experienced drug-related bilirubin increase. Four patients had drug-related serious AEs, including one neutropaenia-related death. Haematologic toxicities were more frequent than in previous tivantinib studies but were manageable with prompt therapy. Best response was stable disease (median, 5.3 months) in 9 of 16 evaluable patients (56%). Median time to progression was 3.3 months. CONCLUSION: Tivantinib demonstrated a manageable safety profile and preliminary antitumour activity in patients with HCC and Child-Pugh A or B cirrhosis.

Loss of matrix adhesion triggers rapid transformation-selective apoptosis in fibroblasts.

Cell-matrix and cell-cell adhesion are recognized physiological determinants of cell growth and survival. In epithelial and endothelial cell systems, oncogenic transformation has in several cases been shown to confer resistance to apoptosis upon depriving cells of substrate adhesion. We examined the effects of oncogenic transformation in adherent versus adhesion- deprived primary embryonic fibroblasts. Whereas untransformed early passage fibroblasts undergo cell cycle arrest, their Myc/Ras- or E1A/Ras-transformed counterparts rapidly enter apoptosis when placed into suspension. This phenomenon also occurs upon incubation with a soluble, RGD-containing integrin ligand and is blocked by a peptide antagonist to ICE family proteases or by aggregation of cells plated at high density. Loss of wild-type p53 modulates the kinetics but does not abrogate this death pathway. Transformation with activated Src rather than Ras rendered fibroblasts selectively resistant to adhesion-dependent apoptosis, an effect likely related to Src's role in integrin signaling, while simultaneously sensitizing the cells to radiation-induced apoptosis. Thus cell adhesion events regulate transformation-selective apoptosis in fibroblasts and provide potentially important targets for understanding and interfering with tumor cell viability.

Development and validation of a liquid chromatography-tandem mass spectrometry method for the determination of ARQ 501 (beta-lapachone) in plasma and tumors from nu/nu mouse xenografts.

A sensitive and specific LC-MS/MS method employing positive electrospray ionization for the determination of ARQ 501 (beta-lapachone) in (nu/nu) mouse plasma and tumor tissue is described. Samples were processed using protein precipitation with acetonitrile. A d6 analog of ARQ 501 was used as the internal standard (IS). The analytes were separated using a Zorbax SB8 column (30 mm x 2.1 mm i.d. 5 microm particle size) and analyzed in the multiple reaction monitoring (MRM) mode using mass transitions of 243>159 and 249>159 m/z for ARQ 501 and d6-ARQ 501, respectively. The lower limit of quantitation (LLOQ) for ARQ 501 was 3.0 ng/mL. The calibration curve was linear in the range of 3.0-2000 ng/mL with a correlation coefficient better than 0.99. Intra- and inter-batch precisions were within 8.4% for plasma and 11.8% for tumor samples. Accuracy expressed as percentage relative error (%R.E.) ranged from -9.0 to 7.7 for both plasma and tumor samples. Recovery was between 106 and 113% for both ARQ 501 and its d6 analog. Plasma pharmacokinetic data of ARQ 501 in mouse from intraperitoneal (IP) dosing at 60 mg/kg obtained using this validated method is presented along with tumor concentration data. The C(max), AUC(0-infinity), t(1/2), Cl/F, and V(d)/F were determined to be 4016 ng/mL, 4392 h ng/mL, 3.9 h, 13.7 L/h/kg, and 76.5 L/kg, respectively. Tumor tissue concentrations were in the range 1-2 microM for approximately 2 h post-dose.

Changes in gene and protein expression in magnetic field-treated human glioma cells.

Because few cancer studies have examined protein profiles and genetic regulation from a single carcinogen exposure, the objective of this study was to determine genetic change via microarray and to evaluate whether that change was a precursor to cellular protein changes. In separate but experimentally identical studies, human glioma SF767 cells were exposed for 3 h to 60-Hz magnetic fields (sham or 1.2 muT). Microarray results suggested that magnetic field treatment resulted in the up-regulation of 5 genes, whereas 25 genes were down-regulated. The mean abundance of 10 identified proteins was altered following 1.2 muT exposure relative to sham (3 increase, 7 decrease). These studies suggest a limited but complicated response in the glioma cells to the magnetic field treatment.

Induction of ornithine decarboxylase activity by 4,4'-methylene bis(2-chloroaniline) in the rat.

The effects of the curative extender 4,4'-methylene bis (2-chloraniline) (MOCA), an established experimental carcinogen that exhibits activity in rat liver, on hepatic ornithine decarboxylase (ODC) activity was investigated. Male Sprague-Dawley rats were injected i.p. with 75 mg/kg MOCA and killed 6, 12, 18, 24, 42 and 48 h later. Stimulation with MOCA of liver cytosolic ODC was first evident at 6 h, peaked at 12 h and returned to control levels by 42 h. The liver enzyme was refractory to stimulation by a second treatment of MOCA within the dosing intervals examined. The magnitude of stimulation of the enzyme by this aromatic amine was dependent on dose and route of administration.

Induction by chloroform of two forms of ornithine decarboxylase in rat liver. Half-life of isozymes.

Ornithine decarboxylase (ODC) in rat liver was separated into two species by DEAE-Sepharose CL-6B column chromatography. The activity of both species of ODC was increased at least 20-fold by chloroform treatment of the rats. The major species, Peak A, contained 65% of the ODC activity and possessed a half-life of 11 min. The second species, Peak B, accounted for 35% of the activity and possessed a half-life of 50 min. The long-lived species of ODC activity, induced in rat liver by chloroform, has not been reported previously and might be related to the prolonged induction of ODC activity by chloroform and to tumor promotion and growth.

Chloroform induction of ornithine decarboxylase activity in rats.

Chloroform is a drinking water contaminant that has been demonstrated to be carcinogenic to mice and rats resulting in an increased incidence of liver and kidney tumors, respectively. The mechanism of chloroform carcinogenicity might be by tumor initiation and/or promotion. Since induction of ornithine decarboxylase (ODC) activity has been proposed as a molecular marker for tumor promoters, we have investigated the effect of chloroform on ODC activity in rats. Chloroform induced a dose-dependent increase of hepatic ODC with an apparent threshold at 100 mg/kg body weight. Female rats were two to four times more susceptible to to chloroform. Upon daily dosing of chloroform for 7 days the liver became less susceptible, with the last dose of chloroform resulting in only 10% of the activity observed after a single dose. Nuclear RNA polymerase I activity was also induced by chloroform. Chloroform, rather than increasing the activity of renal ODC, resulted in a 35% reduction. The induction by chloroform of hepatic ODC activity might be associated with regenerative hyperplasia while the renal carcinogenicity of chloroform could not be demonstrated to be associated with ODC induction.

Applications of mechanistic data in risk assessment: the past, present, and future.

Mechanistic data, when available, have long been considered in risk assessment, such as in the development of the nitrate RfD based on effects in a sensitive group (infants). Recent advances in biology and risk assessment methods have led to a tremendous increase in the use of mechanistic data in risk assessment. Toxicokinetic data can improve extrapolation from animals to humans and characterization of human variability. This is done by the development of improved tissue dosimetry, by the use of uncertainty factors based on chemical-specific data, and in the development of physiologically based pharmacokinetic (PBPK) models. The development of the boron RfD illustrates the use of chemical-specific data in the improved choice of uncertainty factors. The draft cancer guidelines of the U.S. Environmental Protection Agency emphasize the use of mode of action data. The first choice under the guidelines is to use a chemical-specific, biologically based dose-response (BBDR) model. In the absence of a BBDR model, mode of action data are used to determine whether low-dose extrapolation is done using a linear or nonlinear (margin of exposure) approach. Considerations involved in evaluating a hypothesized mode of action are illustrated using 1,3-dichloropropene, and use of a BBDR model is illustrated using formaldehyde. Recent developments in molecular biology, including transgenic animals, microarrays, and the characterization of genetic polymorphisms, have significant potential for improving risk assessments, although further methods development is needed. Overall, use of mechanistic data has significant potential for reducing the uncertainty in assessments, while at the same time highlighting the areas of uncertainty.

Mutagenicity of N-OH-MOCA (4-amino-4'-hydroxylamino-bis-3,3'-dichlorodiphenylmethane) and PBQ (2-phenyl-1,4-benzoquinone) in human lymphoblastoid cells.

The genotoxic potential of two occupationally significant chemicals, 4,4'-methylene-bis-2-chloroaniline (MOCA) and 2-phenyl-1,4-benzoquinone (PBQ), was explored by monitoring the induction of mutations at the HPRT locus of AHH-1 human lymphoblastoid cells. Exposure of AHH-1 cells to the putative carcinogenic metabolite of MOCA, N-OH-MOCA, induced a 6-fold increase in mutant frequency and resulted in base pair substitutions primarily at A:T base pairs. In contrast, exposure to PBQ did not result in an increased mutant frequency although this compound was significantly more cytotoxic than N-OH-MOCA at equimolar doses. The induction of mutations at A:T sites by N-OH-MOCA is consistent with the type of DNA damage known to be produced by MOCA and provides a specific marker of genotoxic damage for exposed populations.

Effect of chloroform on hepatic and renal DNA synthesis and ornithine decarboxylase activity in mice and rats.

Chloroform administered intraperitoneally (i.p.) to male mice and rats resulted in a dose-dependent increase in hepatic ornithine decarboxylase (ODC) activity. Maximal induction of the enzyme in mice was 10-fold and occurred at 375 mg/kg chloroform; in rats it was 52-fold and occurred at 750 mg/kg chloroform. Chloroform increased in mice and decreased in rats the rate of hepatic and renal DNA synthesis. Therefore, the induction of ODC activity in rat liver was not followed with an increase in DNA synthesis. The implications of these results to the proposed nongenetic mechanism of chloroform induction of hepatocellular carcinoma in mice and renal tumors in rats are discussed.

Occupational applications of a human cancer research model.

Many bladder cancers are indolent, and since there are no biomarkers to predict progression, the prognosis is problematic. Utilizing an in vitro/in vivo human uroepithelial cell (SV-HUC.PC) transformation system, we investigated several molecular events occurring along the continuum of exposure to disease outcome as potential biomarkers for occupational carcinogenesis. The model also served to generate information on the occupational carcinogenicity of N-hydroxy-4,4'-methylene bis(2-chloroaniline) [N-OH-MOCA]. Two of 14 groups of SV-HUC.PC treated with various concentrations of N-OH-MOCA formed carcinomas in athymic nude mice. Each of the biomarkers investigated demonstrated potential for interventions/prevention applications of occupational bladder cancers but will require validation and further evaluation. Those investigated displaying potential occupational utility included the induction of ornithine decarboxylase (ODC), DNA adducts, and altered proteins, as detected on HUC two-dimensional polyacrylamide gel electrophoresis protein maps.

Ornithine decarboxylase activity in tissues from rats exposed to 60 Hz magnetic fields, including harmonic and transient field characteristics.

Ornithine decarboxylase (ODC) activity is used widely as a biomarker for tumor promotion in animal model systems. Several previous studies have reported increases in ODC activity in tissues of rats exposed to 60 Hz magnetic fields. The goals of this study were to confirm these findings and to determine whether ODC activity is increased in tissues of animals exposed to magnetic fields containing complex metrics. Three experiments were conducted in male F344 rats. Each study included a sham control group and a group exposed to pure continuous 60 Hz fields (0.2 mT). Additional groups included animals exposed to randomly time-varying 60 Hz fields (range of 0.02 to 0.2 mT); intermittent 60 Hz fields (2 mT) with on-off cycles ranging from 5 s to 5 min; pure continuous 180 Hz fields (2 mT); 60 Hz fields with a superimposed 3rd harmonic (total field strength, 2 mT); 60 Hz fields with superimposed third, fifth, and seventh harmonics (total field strength, 2 mT); 60 Hz fields (2 mT) with superimposed transients; and randomly time-varying 60 Hz fields (range of 0.02 to 0.2 mT) with superimposed transients. After 4 weeks of exposure (18.5 h/day), eight animals per group were euthanized within 1 h of magnetic field deactivation. Homogenates of liver, kidneys, spleen, and brain were prepared from each animal, quick-frozen, and shipped for analysis by four independent laboratories. No consistent pattern of differences in the ODC activity among experimental groups was found either within a laboratory or among laboratories. The results do not support the hypothesis that exposure to extremely low frequency magnetic fields stimulates ODC activity.

Investigation of protein expression in magnetic field-treated human glioma cells.

We previously reported phenotypic changes in human breast cancer cells following low-level magnetic field (MF) exposure. Here proteomic methods were used to investigate the biochemical effect of MF exposure in SF767 human glioma cells. Protein alterations were studied after exposure to 1.2 microTesla (microT) MF [12 milliGauss (mG), 60 Hertz (Hz)] +/- epidermal growth factor (EGF). SF767 cells were exposed for 3 h to sham conditions (<0.2 microT ambient field strength) or 1.2 microT MF (+/-EGF; 10 ng/ml). Solubilized protein fractions (sham; 1.2 microT; sham + EGF; 1.2 microT + EGF) were loaded for electrophoresis by 2D-PAGE and stained using a colloidal Coomassie blue technique to resolve and characterize the proteins. Protein patterns were compared across groups via Student's t-test using PDQUEST software. Cell profiles revealed significant alterations in the spot density of a subset of treated cells. Automated spot excision and processing was performed prior to peptide mass fingerprinting proteins of interest. Fifty-seven proteins from the detectable pool were identified and/or found to differ significantly across treatment groups. The mean abundance of 10 identified proteins was altered following 1.2 microT exposure. In the presence of EGF six proteins were altered after low magnetic field treatment by increasing (4) or decreasing (2) in abundance. The results suggest that the analysis of differentially expressed proteins in SF767 cells may be useful as biomarkers for biological changes caused by exposure to magnetic fields.

Effect of phenobarbital on cytoplasmic and nuclear distribution of 3H-arginine in rat liver.

Rat liver derived from animals receiving phenobarbital (80 mg/kg intraperitoneally) exhibited an increase in the cytoplasmic concentration of radioactive amino acid (initially injected as arginine) as early as 1 hour after the injection. This increase in uptake resulted in an unequal distribution of the radioactivity between the cytoplasmic and nuclear compartments; while other organelles retained their normal (per cent) allotment of the radioactivity. The cytoplasmic and nucleoplasmic protein profiles from gel chromatography show quantitative changes that may be due to increased synthesis and migration of a cytoplasmic protein to the nucleus where its nuclear function remains to be examined more thoroughly.

Chloroform induction of ornithine decarboxylase antizyme (ODC-AZ) in male rat liver.

Chloroform stimulation of rat hepatic ODC is most dramatic at 18 h following a single injection. Repeated dosing, 1 dose/d for up to 7 d, results in a daily decline in the ability of the liver enzyme to respond 18 h after the final injection. We postulated that this decline was due to an increased synthesis and accumulation of the OCD-AZ protein. ODC-AZ was determined by measuring the inhibition of isolated ODC activity as described by Hayashi and Fujita and modified in our laboratory to use kidney ODC. Male and female Fischer 344 rats were injected daily for 1, 3, or 7 d with 3.0 mmol/kg chloroform. Chloroform induced ODC-AZ activity in males at 3 and 7 d (26% and 37% inhibition of the ODC activity in the incubation medium, respectively). While females exhibited a similar decline in ODC activity after repeated doses, ODC-AZ was not induced. Thus, it would appear that daily exposure of rats to chloroform results in a refractoriness of its induction of ODC activity accompanied by an induction of the ODC-AZ in males. However, in females these two responses were not directly related.

Effect of alpha-difluoromethylornithine, an irreversible ornithine decarboxylase inhibitor, on formation of GGTase-positive foci.

The importance of the induction of ornithine decarboxylase to the development of GGTase foci is examined in the classic initiation-promotion assay. This was accomplished by examining the complete foci system in the presence and absence of alpha-DFMO, an irreversible inhibitor of ornithine decarboxylase, at concentrations capable of inhibiting both phenobarbital stimulated and control levels of the enzyme. Although the hepatic enzyme was inhibited by the alpha-DFMO, there was no decrease in the progression of formation of the GGTase foci.

An organofluorophosphate-hydrolyzing activity in Tetrahymena thermophila.

An enzymatic activity that hydrolyzes O,O-diisoproplyphosphofluoridate (DFP) and O-1,2,2-trimethylpropylmethylphosphonofluoridate (Soman) was discovered in the ciliate protozoan Tetrahymena thermophila. The enzymatic activity classifies the protein as Mazur-type similar to that found in hog kidney and Escherichia coli. The rate of hydrolysis of Soman by the Tetrahymena-extract is the highest, on a per gram of extract basis, of any eucaryote. The molecular weight is approximately 75,400 as determined by Sephacryl column chromatography. A maximum fifteen-fold purification has been achieved. Potential exists for the detoxification and one-step detection of common organofluorophosphate pollutants. Additionally, Tetrahymena should prove an easier subject for manipulation than mammalian or squid sources. Protozoa may be a potentially important source of detoxification and degradation enzymes for other environmental contaminants.