BackgroundThe phosphatidylinositol 3 kinase (PI3K) signalling pathway is frequently altered in human cancer and a promising therapeutic target. AZD8186 (AstraZeneca) is a PI3Kβ/δ inhibitor, currently in phase 1 clinical trials. 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) is often used as a biomarker for inhibitors targeting the PI3K axis because of the association of this pathway with glucose metabolism. In this study, we assessed if 18F-FDG PET could be used as a pharmacodynamic marker to monitor PI3Kβ inhibition by AZD8186, and hence have potential as a clinical biomarker of PI3Kβ pathway activation, and for patient selection. 18F-FDG PET scans were performed in nude mice bearing 786-0 renal, U87-MG glioma, and BT474C breast xenograft models. Mice were fasted prior to imaging and static 18F-FDG PET imaging was performed. Tumour growth was monitored throughout each study, and at the end of the imaging procedure, tumours were taken and a full pharmacodynamic analysis performed.ResultsResults showed that in PTEN null tumour xenograft models, 786-0 and U87-MG, the PI3Kβ inhibitor AZD8186 reduces 18F-FDG uptake at a dose of 50 mg/kg, the same dose which causes tumour inhibition, while it has no impact in a PI3Kα mutant tumour xenograft BT474C. Consistent with the change in 18F-FDG uptake, AZD8186 also modulated AKT and associated glucose pathway biomarkers in the PTEN null tumour xenografts but not in PTEN wild-type tumours.ConclusionsOur pre-clinical studies support the use of 18F-FDG PET imaging as a sensitive and non-invasive pharmacodynamic biomarker for use in clinical studies with AZD8186.Electronic supplementary materialThe online version of this article (doi:10.1186/s13550-016-0220-9) contains supplementary material, which is available to authorized users.

R123 is a sensitive potentiometric dye in C. reinhardtii that may find further use in investigations of both mitochondrial bioenergetics in plants and environmental toxicology.

BackgroundThe phosphatidyl inositol 3 kinase (PI3K), AKT and mammalian target of rapamycin (mTOR) signal transduction pathway is frequently de-regulated and activated in human cancer and is an important therapeutic target. AZD8835 is a PI3K inhibitor, with selectivity against PI3K α and δ isoforms, which is currently in Phase 1 clinical trials. 18F-Fluoro-deoxy-glucose positron emission tomography (18F-FDG PET) is a non-invasive pharmacodynamic imaging biomarker that has become an integral part of drug development. It has been used widely with PI3K inhibitors both clinically and pre-clinically because of the role of the PI3K pathway in glucose metabolism. In this study we investigated the potential of 18F-FDG PET as a non-invasive pharmacodynamic biomarker for AZD8835. We sought to understand if 18F-FDG PET could determine the minimally effective dose of AZD8835 and correlate with other pharmacodynamic biomarkers for validation of its use in clinical development. 18F-FDG PET scans were performed in nude mice in the BT474C breast xenograft model. Mice were fasted prior to imaging and static 18F-FDG PET was performed. Treatment groups received AZD8835 by oral gavage at a dose volume of 10ml/kg. Treatment groups received either 3, 6, 12.5, 25 or 50mg/kg AZD8835. Tumour growth was monitored throughout the study, and at the end of the imaging procedure, tumours were taken and a full pharmacodynamic analysis was performed.ResultsResults showed that AZD8835 reduced 18F-FDG uptake at a dose of 12.5, 25 and 50mg/kg with no significant reduction at doses of 3 and 6mg/kg. These results were consistent with other pharmacodynamics biomarkers measured and show 18F-FDG PET as a sensitive biomarker with the ability to determine the minimal effective dose of AZD8835.ConclusionsOur pre-clinical studies support the use of 18F-FDG PET imaging as a sensitive and non- invasive pharmacodynamic biomarker (understanding the role of PI3K signalling in glucose uptake) for AZD8835 with a decrease in 18F-FDG uptake observed at only two hours post treatment. The decrease in 18F-FDG uptake was dose dependent and data showed excellent PK/PD correlation. This data supports and parallels observations obtained with this class of compounds in patients