Predicting response to RAD001 treatment in post-menopausal women with ER-positive breast cancer using the breast cancer DSA™ research tool (Almac)

Abstract #2032

Background: RAD001 (everolimus) is a rapamycin derivative that inhibits mTOR and its downstream substrates and has shown promising results in Phase I trials. The aim of this study was to assess the feasibility of predicting patient response to RAD001 treatment from pre-treatment biopsies.
 Materials & Methods: 32 post-menopausal, ER-positive early breast cancer patients received 5mg RAD001 pre-operative treatment daily for 14 days prior to primary surgery. 25 patients completed the regimen, 6 patients withdrew and 1 did not start treatment. Biopsies were taken at diagnosis and at surgery from the RAD001 treated patients. Pre-treatment samples were flash frozen prior to RNA isolation. Patient response status was classified based on the % of Ki-67 positive cells determined by immunohistochemistry in the post-treatment biopsy (Macaskill et al., 2006: Breast Cancer Research & Treatment: 100: S1: S286). RNA from the pre-treatment group was analysed using the Almac Diagnostics Breast Cancer DSATM Research Tool, which represents ∼60,000 normal breast and breast cancer transcripts and Illumina Human Ref.8 chip v2 containing ∼24,500 transcripts representing well-categorised and most commonly known genes, irrespective of disease or tissue. For each array platform, modulated genes were identified using statistically robust gene selection methods. In addition, the sequence content of the two platforms was compared by probe-level analysis using BLAST.
 Results & Discussion: Preliminary assessment of the expression differences between the non-responder and responder groups using the DSA™ Research Tool demonstrated 169 up-regulated and 93 down-regulated genes. This list is comprised of genes involved in chemokine activity, cell adhesion and transport. Cross-platform content comparison demonstrated that the Illumina bead arrays represented 41% of transcripts on the DSA™ Research Tool whilst 82% of the Illumina beadarray transcripts were represented on the DSA™ Research Tool. Genes of interest identified will be validated by quantitative real time PCR and the key pathways reported.
 These datasets have enabled us to begin the identification of tumours most suited to RAD001 treatment and may be used as a guide for the generation of a gene expression classifier for predicting patient response to RAD001.
 Acknowledgements: This work was supported by a grant from Breast Cancer Research Treatment, UK.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2032.

An evaluation of three new-generation tetrazolium salts for the measurement of respiratory activity in activated sludge microorganisms

XTT (3'-[1-[(phenylamino)-carbonyl]-3,4-tetrazolium]-bis(4-methoxy-6-nitro)benzenesulfonic acid hydrate), MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt), and WST-1 (4-(3-4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio)-1,3-benzenedisulfonate) are tetrazolium salts that have become commercially available only in relatively recent years; they differ from earlier such compounds in that their reduction gives rise to a formazan product that is water soluble. We have established the sites in the prokaryotic respiratory chain at which each of the dyes is reduced to its corresponding formazan and have evaluated the suitability of each for the colorimetric estimation of electron transport system activity in populations of activated sludge microorganisms. Reduction of all three tetrazolium salts was shown to be proportional to cell biomass and oxygen uptake and to be susceptible to low levels of the reference toxicant 3,5-dichlorophenol. XTT, which was not inhibitory at concentrations of up to 2 mM and was reduced by 91% of isolates from a sample of culturable activated sludge bacteria, was chosen for further assay development. XTT-formazan production was found to be stimulated by the availability of an exogenous carbon and energy source, and by the presence of the electron-coupling agent phenazine methosulfate. Less than 3% of XTT reduction by an activated sludge sample was abiotic. An assay based on this compound could be a valuable and simple tool for the routine monitoring of the performance of wastewater treatment systems.

Coordination between respiration and deglutition in a preterm infant mammal, Sus scrofa

In adult mammals, the path of a swallowed bolus of solid food crosses the laryngeal opening, so that coordination between respiration and deglutition is critical for airway protection. The nature of such coordination in preterm, low-birth-weight infants with immature nervous systems, is not clear. Using preterm pigs as a model, two measures of respiration were recorded and then coordinated with a high-resolution cineradiographic record of swallowing. Swallows, divided into three distinct events, began before inhalation ended, but expiration did not start until after the milk had passed around the laryngeal opening. These results support the idea that a high degree of coordination between swallowing and respiration exists in preterm infant pigs, although other aspects of the nervous system have not fully matured.