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Contrast Media & Molecular Imaging
Volume 2018, Article ID 1269830, 9 pages
https://doi.org/10.1155/2018/1269830
Research Article

Preclinical In Vitro and In Vivo Evaluation of [18F]FE@SUPPY for Cancer PET Imaging: Limitations of a Xenograft Model for Colorectal Cancer

1Biomedical Imaging and Image-Guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria
2Department of Pharmaceutical Technology and Biopharmaceutics, Faculty of Life Sciences, University of Vienna, Vienna, Austria
3Institute of Pathophysiology and Allergy Research, Center of Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
4Department of Internal Medicine II, University Hospital Krems, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
5Department of Radiation Oncology, Division of Medical Physics, Medical University of Vienna, Vienna, Austria
6Comparative Medicine, The Interuniversity Messerli Research Institute, The University of Veterinary Medicine Vienna, Medical University of Vienna, and University of Vienna, Vienna, Austria
7Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, Vienna, Austria
8Department of Surgery, Surgical Research Laboratories, Medical University of Vienna, Vienna, Austria
9Institute of Organic Chemistry, University of Vienna, Vienna, Austria
10Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria
11CBmed GmbH, Graz, Austria
12Ludwig Boltzmann Institute Applied Diagnostics, Vienna, Austria

Correspondence should be addressed to M. Mitterhauser; ta.ca.neiwinudem@resuahrettim.sukram

Received 23 November 2017; Accepted 27 December 2017; Published 13 February 2018

Academic Editor: Giorgio Biasiotto

Copyright © 2018 T. Balber et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Molecular imaging probes such as PET-tracers have the potential to improve the accuracy of tumor characterization by directly visualizing the biochemical situation. Thus, molecular changes can be detected early before morphological manifestation. The A3 adenosine receptor (A3AR) is described to be highly expressed in colon cancer cell lines and human colorectal cancer (CRC), suggesting this receptor as a tumor marker. The aim of this preclinical study was the evaluation of FE@SUPPY as a PET-tracer for CRC using in vitro imaging and in vivo PET imaging. First, affinity and selectivity of FE@SUPPY and its metabolites were determined, proving the favorable binding profile of FE@SUPPY. The human adenocarcinoma cell line HT-29 was characterized regarding its hA3AR expression and was subsequently chosen as tumor graft. Promising results regarding the potential of FE@SUPPY as a PET-tracer for CRC imaging were obtained by autoradiography as ≥2.3-fold higher accumulation of FE@SUPPY was found in CRC tissue compared to adjacent healthy colon tissue from the same patient. Nevertheless, first in vivo studies using HT-29 xenografts showed insufficient tumor uptake due to (1) poor conservation of target expression in xenografts and (2) unfavorable pharmacokinetics of FE@SUPPY in mice. We therefore conclude that HT-29 xenografts are not adequate to visualize hA3ARs using FE@SUPPY.