Synthesis and biological evaluation of novel phosphatidylinositol 3-kinase inhibitors: Solubilized 4-substituted benzimidazole analogs of 2-(difluoromethyl)-1-[4,6-di(4-morpholinyl)-1,3,5-triazin-2-yl]-1H-benzimidazole (ZSTK474).

A range of 4-substituted derivatives of the pan class I PI 3-kinase inhibitor 2-(difluoromethyl)-1-[4,6-di-(4-morpholinyl)-1,3,5-triazin-2-yl]-1H-benzimidazole (ZSTK474) were prepared in a search for more soluble analogs. 4-Aminoalkoxy substituents provided the most potent derivatives, with the 4-O(CH2)3NMe2 analog (compound 14) being identified as displaying the best overall activity in combination with good aqueous solubility (25 mg/mL for the hydrochloride salt). This compound was tested in a U87MG xenograft model, but displayed less potency than ZSTK474 as a result of an unfavorable pharmacokinetic profile.

Comparison of a homologous series of benzonaphthyridine anti-cancer agents in mice: divergence between tumour and plasma pharmacokinetics.

Purpose: N-[2-(dimethylamino)ethyl]-2,6-dimethyl-1-oxo-1,2-dihydrobenzo[b]-1,6-naphthyridine-4-carboxamide (SN 28049), a DNA-binding benzonaphthyridine, has shown curative activity against colon-38 adenocarcinoma after a single dose in mice. A homologous series of 5 compounds, where the 2-methyl group was replaced by a hydrogen, ethyl, propyl, or butyl, was used to evaluate the role of lipophilicity and tumour pharmacokinetics on their antitumour activity.

Methods: All analogues were administered (25 μmol/kg) to healthy and tumour-bearing C57 Bl/6 mice and concentrations were measured in plasma, brain, heart, kidney, liver, lung, and tumour tissues.

A rapid LC-MS/MS method for the quantitation of a series of benzonaphthyridine derivatives: application to in vivo pharmacokinetic and lipophilicity studies in drug development.

Drug lipophilicity is a vital physicochemical parameter that influences drug absorption, distribution, metabolism, excretion and toxicology. A comparative study of a homologous series based on a pharmaceutically active drug represents a powerful approach to the study of the effects of drug lipophilicity. We have developed a rapid and sensitive LC-MS/MS method suitable for such a homologous series and applied it to a series of DNA binding benzonaphthyridine-based antitumour drugs of differing lipophilicity.

Comparative effects in rats of intact wheat bran and two wheat bran fractions on the disposition of the mutagen 2-amino-3-methylimidazo[4,5-f]quinoline.

Wheat bran protects against mutations and cancer, but contains different plant cell types that are likely to have different protective effects. We previously described the production and chemical characterisation of an aleurone-rich fraction (ARF) and a pericarp-rich fraction (PRF) from wheat grain. We compared these with whole bran (WB), fed to rats as 10% of a high fat AIN-76 diet.

Therapeutic reactivation of mutant p53 protein by quinazoline derivatives.

Purpose: The human tumour suppressor protein p53 is mutated in nearly half of human tumours and most mutant proteins have single amino acid changes. Several drugs including the quinazoline derivative 1 (CP-31398) have been reported to restore p53 activity in mutant cells. The side chain of 1 contains a styryl linkage that compromises its stability and we wished to explore the activity of analogues containing more stable side chains.

Synthesis and biological evaluation of novel analogues of the pan class I phosphatidylinositol 3-kinase (PI3K) inhibitor 2-(difluoromethyl)-1-[4,6-di(4-morpholinyl)-1,3,5-triazin-2-yl]-1H-benzimidazole (ZSTK474).

A structure-activity relationship (SAR) study of the pan class I PI 3-kinase inhibitor 2-(difluoromethyl)-1-[4,6-di(4-morpholinyl)-1,3,5-triazin-2-yl]-1H-benzimidazole (ZSTK474) identified substitution at the 4 and 6 positions of the benzimidazole ring as having significant effects on the potency of substituted derivatives. The 6-amino-4-methoxy analogue displayed a greater than 1000-fold potency enhancement over the corresponding 6-aza-4-methoxy analogue against all three class Ia PI 3-kinase enzymes (p110α, p110β, and p110δ) and also displayed significant potency against two mutant forms of the p110α isoform (H1047R and E545K). This compound was also evaluated in vivo against a U87MG human glioblastoma tumor xenograft model in Rag1(-/-) mice, and at a dose of 50 mg/kg given by ip injection at a qd × 10 dosing schedule it dramatically reduced cancer growth by 81% compared to untreated controls.

Pharmacokinetics and distribution of SN 28049, a novel DNA binding anticancer agent, in mice.

Purpose: N-[2-(Dimethylamino)ethyl]-2,6-dimethyl-1-oxo-1,2-dihydrobenzo[b]-1,6-naphthyridine-4-carboxamide (SN 28049) is a potent DNA binding topoisomerase II poison that shows excellent antitumour activity in a colon-38 murine tumour model in comparison to standard topoisomerase II poisons. We report here the preclinical pharmacokinetics of SN 28049.

Methods: C57 Bl/6 mice (n = 3 per time point) were treated with a single i.

Development and validation of a liquid chromatography-mass spectrometry (LC-MS) assay for the determination of the anti-cancer agent N-[2-(dimethylamino)ethyl]-2,6-dimethyl-1-oxo-1,2-dihydrobenzo[b]-1,6-naphthyridine-4-carboxamide (SN 28049).

N-[2-(Dimethylamino)ethyl]-2,6-dimethyl-1-oxo-1,2-dihydrobenzo[b]-1,6-naphthyridine-4-carboxamide (SN 28049) is a potent topoisomerase II poison being developed to treat solid tumours. A reliable and sensitive LC-MS method has been developed and validated for the determination of SN 28049 in plasma using a structurally similar internal standard. This method had acceptable intra- and inter-assay accuracy (95-105%) and precision (R.

Enhancement of the action of the antivascular drug 5,6-dimethylxanthenone-4-acetic acid (DMXAA; ASA404) by non-steroidal anti-inflammatory drugs.

Aim: 5,6-Dimethylxanthenone-4-acetic acid (DMXAA) (ASA404), a low molecular weight antivascular drug currently in clinical trial, acts both directly on the tumour vascular endothelium and indirectly through the induction of inflammatory cytokines and other vasoactive molecules from macrophages and other host cells. We wished to determine whether co-administration of non-steroidal anti-inflammatory drugs (NSAIDs) could modulate the antivascular effects of DMXAA in mice.

Methods: The effects of diclofenac, salicylate, ibuprofen, celecoxib and rofecoxib on the antitumour response to DMXAA were compared using growth delay assays of Colon 38 adenocarcinomas in C57Bl mice.

Rat tumor response to the vascular-disrupting agent 5,6-dimethylxanthenone-4-acetic acid as measured by dynamic contrast-enhanced magnetic resonance imaging, plasma 5-hydroxyindoleacetic acid levels, and tumor necrosis.

The dose-dependent effects of 5,6-dimethylxanthenone-4-acetic acid (DMXAA) on rat GH3 prolactinomas were investigated in vivo. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was used to assess tumor blood flow/permeability pretreatment and 24 hours posttreatment with 0, 100, 200, or 350 mg/kg DMXAA. DCE-MRI data were analyzed using K(trans) and the integrated area under the gadolinium time curve (IAUGC) as response biomarkers.

Inhibition of human CYP1A2 oxidation of 5,6-dimethyl-xanthenone-4-acetic acid by acridines: a molecular modelling study.

1. The aim of the present study was to investigate the structural requirements for the inhibition of 6-methyl-hydroxylation of the antitumour agent 5,6-dimethyl-xanthenone-4-acetic acid (DMXAA) by acridine analogues and use a CYP1A2 homology model to provide some insight into this interaction. 2.

Mechanisms of tumor vascular shutdown induced by 5,6-dimethylxanthenone-4-acetic acid (DMXAA): Increased tumor vascular permeability.

The novel vascular targeting agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA) has completed phase 1 clinical trial and has shown tumor antivascular activity in both mice and humans. We have investigated its ability to change tumor vascular permeability, relating it to tumor vascular perfusion and other responses. The murine colon 38 adenocarcinoma was grown in C57Bl wild-type mice and mice lacking expression of either tumor necrosis factor receptor-1 (TNFR1(-/-)) or TNF (TNF-/-).

Transport of the investigational anti-cancer drug 5,6-dimethylxanthenone-4-acetic acid and its acyl glucuronide by human intestinal Caco-2 cells.

5,6-Dimethylxanthenone-4-acetic acid (DMXAA), a potent cytokine inducer, exhibited marked antitumor activity when given as multiple oral doses in mice. The aim of this study was to examine the transport of DMXAA and its acyl glucuronide (DMXAA-G) using the human Caco-2 cells. DMXAA was minimally metabolized by Caco-2 cells and both DMXAA and DMXAA-G were taken up to a minor extent by the cells.

Application of liquid chromatography-mass spectrometry to monitoring plasma cyclophosphamide levels in phase I trial cancer patients.

A specific and efficient liquid chromatography-mass spectrometry (LC-MS) method was established for monitoring patient plasma cyclophosphamide levels in a phase I trial of an oral cyclophosphamide-based combination chemotherapy regimen. An Agilent 1100 Series LC-MSD system (Agilent Technologies, Avondale, PA, USA), with a single quadrupole mass detector using a positive atmospheric pressure chemical ionization (APCI) interface and single ion monitoring at m/z 261, was used. Chromatography was performed using a LUNA C8 5 microm 30 x 4.

Thalidomide pharmacokinetics and metabolite formation in mice, rabbits, and multiple myeloma patients.

Purpose: Thalidomide has a variety of biological effects that vary considerably according to the species tested. We sought to establish whether differences in pharmacokinetics could form a basis for the species-specific effects of thalidomide.

Experimental Design: Mice and rabbits were administered thalidomide (2 mg/kg) p.

Determination of the investigational anti-cancer drug 5,6-dimethylxanthenone-4-acetic acid and its acyl glucuronide in Caco-2 monolayers by liquid chromatography with fluorescence detection: application to transport studies.

5,6-Dimethylxanthenone-4-acetic acid (DMXAA) is a potent cytokine inducer, with a bioavailability of >70% in the mouse. The aim of this study was to develop and validate HPLC methods for the determination of DMXAA and DMXAA acyl glucuronide (DMXAA-G) in the human intestinal cell line Caco-2 monolayers. The developed HPLC methods were sensitive and reliable, with acceptable accuracy (85-115% of true values) and precision (intra- and inter-assay CV < 15%).

Induction of tumour necrosis factor and interferon-gamma in cultured murine splenocytes by the antivascular agent DMXAA and its metabolites.

The induction of haemorrhagic necrosis by 5,6-dimethylxanthenone-4-acetic acid (DMXAA) in transplantable murine tumours depends on the in situ synthesis of cytokines, particularly tumour necrosis factor (TNF). Since the in vivo action of DMXAA would be greatly clarified by the development of an in vitro model, we investigated whether DMXAA could induce cytokines in cultured murine splenocytes. DMXAA alone induced low amounts of TNF with an optimal concentration of 10 microg/mL and an optimal time of 4 hr.

Metabolism of thalidomide in liver microsomes of mice, rabbits, and humans.

Thalidomide is increasingly important in clinical treatment, not only of various inflammatory conditions but also in multiple myeloma and other malignancies. Moreover, the metabolism of thalidomide varies considerably among different species, indicating a need to understand its mechanistic basis. Our previous in vivo studies showed the plasma half-life of thalidomide to be much shorter in mice than in humans, with rabbits showing intermediate values.

Modulation of thalidomide pharmacokinetics by cyclophosphamide or 5,6-dimethylxanthenone-4-acetic acid (DMXAA) in mice: the role of tumour necrosis factor.

Purpose: There is considerable current interest in the use of thalidomide as a single agent or in combination with drugs such as cyclophosphamide in the treatment of multiple myeloma and other cancers. Our previous work has shown that thalidomide potentiates the antitumour activity of both cyclophosphamide and 5,6-dimethylxanthenone-4-acetic acid (DMXAA) against murine Colon 38 tumours. In both of these cases, thalidomide extends the half-life (t(1/2)) of the other drug.

Improvement of the antitumor activity of intraperitoneally and orally administered 5,6-dimethylxanthenone-4-acetic acid by optimal scheduling.

Purpose: 5,6-Dimethylxanthenone-4-acetic acid (DMXAA), a new anticancer drug that has recently completed Phase I clinical trial, is effective against transplantable murine tumors with established vasculature. We wished to determine the relationship between administration schedule and antitumor activity.

Experimental Design: C57Bl/6 mice with s.

Preclinical factors affecting the interindividual variability in the clearance of the investigational anti-cancer drug 5,6-dimethylxanthenone-4-acetic acid.

Cancer chemotherapy is characterized by significant interindividual variations in systemic clearance, therapeutic response, and toxicity. These variations are due mainly to genetic factors, leading to alterations in drug metabolism and/or target proteins. The aim of this study was to determine, using a human liver bank (N=14), the interindividual variations in the expression and activity of liver enzymes that metabolize the investigational anticancer drug 5,6-dimethylxanthenone-4-acetic acid (DMXAA), i.

Contrasting effects of non-starch polysaccharide and resistant starch-based diets on the disposition and excretion of the food carcinogen, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), in a rat model.

It has commonly been believed that increasing fibre in the diet should reduce the incidence of cancers, especially those of the colon and rectum. The earliest definitions of dietary fibre restricted the term to plant cell walls in which non-starch polysaccharides are key chemical components. However, new definitions encompass a wider range of materials, including starches resistant to digestion in the colon (resistant starches).

Predicting pharmacokinetics and drug interactions in patients from in vitro and in vivo models: the experience with 5,6-dimethylxanthenone-4-acetic acid (DMXAA), an anti-cancer drug eliminated mainly by conjugation.

The novel anti-tumor agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA) was developed in the Auckland Cancer Society Research Center. Its pharmacokinetic properties have been investigated using both in vitro and in vivo models, and the resulting data extrapolated to patients. The metabolism of DMXAA has been extensively studied mainly using hepatic microsomes, which indicated that UGT1A9 and UGT2B7-catalyzed glucuronidation on its acetic acid side chain and to a lesser extent CYP1A2-catalyzed hydroxylation of the 6-methyl group are the major metabolic pathways, resulting in DMXAA acyl glucuronide (DMXAA-G) and 6-hydroxymethyl-5-methylxanthenone-4-acetic acid.

Preclinical factors influencing the relative contributions of Phase I and II enzymes to the metabolism of the experimental anti-cancer drug 5,6-dimethylxanthenone-4-acetic acid.

It is important to determine the relative contribution of each metabolic pathway (f(p)) and of enzymes to the net metabolism of a drug. The aim of this study was to investigate, using a human liver bank, the f(p) of the anti-cancer drug 5,6-dimethylxanthenone-4-acetic acid (DMXAA) and the effects of various inhibitors and inducers on f(p). The mean apparent K(m) and V(max) values (N=14) were 21+/-5 microM and 0.

6-methylhydroxylation of the anti-cancer agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA) by flavin-containing monooxygenase 3.

The involvement of flavin-containing monooxygenase (FMO) in the 6-methylhydroxylation of the experimental anti-cancer drug 5,6-dimethylxanthenone-4-acetic acid (DMXAA) was investigated by use of human liver microsomes and microsomes containing cDNA-expressed FMOs. The involvement of FMO in the formation of 6-methyl hydroxylate of DMXAA, 6-hydroxymethyl-5-methylxanthenone-4-acetic acid (6-OH-MXAA) in human liver microsomes was indicated by the fact that this biotransformation was sensitive to heat treatment, increased at pH 8.3, and inhibited by methimazole.