Abstract 2680: Improved imaging of orthotopic BxPC3 pancreatic adenocarcinoma xenograft using animal PET/CT.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Treatment of pancreatic adenocarcinoma is difficult because the location of the lesion is often unknown. 6-[18F]fluoro-L-3,4-dihydroxyphenylalanine ([18F]FDOPA) is used for imaging of neuroendocrine tumours, which take up and decarboxylate amine precursors. [18F]FDOPA use in diagnostic pancreatic imaging has increased, since the exocrine pancreas synthesises dopamine. We studied the uptake of [18F]FDOPA in healthy and diseased pancreas. Mice bearing orthotopic BxPC3 pancreatic adenocarcinoma and sham-operated controls were pre-treated with enzyme inhibitors of aromatic amino acid decarboxylase (AADC), catechol-O-methyl transferase (COMT), monoamine oxidase A (MAO-A) or combinations of these inhibitors. Mice were injected with 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) or [18F]FDOPA and scanned via positron emission tomography/computed tomography. The absolute [18F]FDOPA uptake was determined from selected tissues using a well counter. The intratumoural biodistribution pattern of [18F]FDOPA was recorded autoradiographically. The main FDOPA metabolites present in pancreatic samples were determined with high-performance liquid chromatography. [18F]FDG uptake was high in pancreatic tumours, while [18F]FDOPA uptake was highest in healthy pancreas and significantly lower in tumour-bearing pancreas, independent of pre-treatment. [18F]FDOPA uptake in pancreas was lowest with vehicle pre-treatment and highest with pre-treatment with the inhibitor of AADC. When mice received COMT+MAO-A inhibitors, uptake was high in healthy pancreas but low in tumour-bearing pancreas. Unequal uptake may be due to blockade of metabolism and increased availability of [18F]fluorodopamine due to the employed enzyme inhibitors. Combined use of [18F]FDG and [18F]FDOPA is suitable for imaging pancreatic tumours. Pre-treatment with COMT+MAO-A inhibitors improved the differentiation of pancreas from surrounding tissue and healthy pancreas from tumour. Citation Format: Johanna M. Tuomela, Jani Seppanen, Laura Haavisto, Sarita Fosrback, Tero Vahlberg, Olof Solin, Merja Haaparanta. Improved imaging of orthotopic BxPC3 pancreatic adenocarcinoma xenograft using animal PET/CT. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2680. doi:10.1158/1538-7445.AM2013-2680