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Open AccessArticle

In Vivo Monitoring of the Antiangiogenic Effect of Neurotensin Receptor-Mediated Radiotherapy by Small-Animal Positron Emission Tomography: A Pilot Study

1
Department of Nuclear Medicine, Laboratory of Molecular Imaging and Radiochemistry, Friedrich Alexander University, Schwabachanlage 6, 91054 Erlangen, Germany
2
Department of Nuclear Medicine, Innsbruck Medical University, Anichstr. 35, 6020 Innsbruck, Austria
3
Department of Chemistry and Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich Alexander University, Schuhstraße 19, 91052 Erlangen, Germany
*
Author to whom correspondence should be addressed.
Pharmaceuticals 2014, 7(4), 464-481; https://doi.org/10.3390/ph7040464
Received: 17 December 2013 / Revised: 4 April 2014 / Accepted: 10 April 2014 / Published: 16 April 2014
(This article belongs to the Special Issue Radiopharmaceutical Chemistry between Imaging and Radioendotherapy)
The neurotensin receptor (NTS1) has emerged as an interesting target for molecular imaging and radiotherapy of NTS-positive tumors due to the overexpression in a range of tumors. The aim of this study was to develop a 177Lu-labeled NTS1 radioligand, its application for radiotherapy in a preclinical model and the imaging of therapy success by small-animal positron emission tomography (µPET) using [68Ga]DOTA-RGD as a specific tracer for imaging angiogenesis. The 177Lu-labeled peptide was subjected to studies on HT29-tumor-bearing nude mice in vivo, defining four groups of animals (single dose, two fractionated doses, four fractionated doses and sham-treated animals). Body weight and tumor diameters were determined three times per week. Up to day 28 after treatment, µPET studies were performed with [68Ga]DOTA-RGD. At days 7–10 after treatment with four fractionated doses of 11–14 MBq (each at days 0, 3, 6 and 10), the tumor growth was slightly decreased in comparison with untreated animals. Using a single high dose of 51 MBq, a significantly decreased tumor diameter of about 50% was observed with the beginning of treatment. Our preliminary PET imaging data suggested decreased tumor uptake values of [68Ga]DOTA-RGD in treated animals compared to controls at day 7 after treatment. This pilot study suggests that early PET imaging with [68Ga]DOTA-RGD in radiotherapy studies to monitor integrin expression could be a promising tool to predict therapy success in vivo. Further successive PET experiments are needed to confirm the significance and predictive value of RGD-PET for NTS-mediated radiotherapy. View Full-Text
Keywords: neurotensin receptor; positron emission tomography; radiotherapy; lutetium-177; RGD peptide; angiogenesis neurotensin receptor; positron emission tomography; radiotherapy; lutetium-177; RGD peptide; angiogenesis
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Maschauer, S.; Ruckdeschel, T.; Tripal, P.; Haubner, R.; Einsiedel, J.; Hübner, H.; Gmeiner, P.; Kuwert, T.; Prante, O. In Vivo Monitoring of the Antiangiogenic Effect of Neurotensin Receptor-Mediated Radiotherapy by Small-Animal Positron Emission Tomography: A Pilot Study. Pharmaceuticals 2014, 7, 464-481.

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