Abstract: 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.
Keywords: 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.
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(4):464-481.
Maschauer, Simone; Ruckdeschel, Tina; Tripal, Philipp; Haubner, Roland; Einsiedel, Jürgen; Hübner, Harald; Gmeiner, Peter; Kuwert, Torsten; Prante, Olaf. 2014. "In Vivo Monitoring of the Antiangiogenic Effect of Neurotensin Receptor-Mediated Radiotherapy by Small-Animal Positron Emission Tomography: A Pilot Study." Pharmaceuticals 7, no. 4: 464-481.