Media type: E-Article Title: A novel PET tracer for the imaging of αvβ3 and αvβ5 integrins in experimental breast cancer bone metastases Contributor: Mühlhausen, Ute; Komljenovic, Dorde; Bretschi, Maren; Leotta, Karin; Eisenhut, Michael; Semmler, Wolfhard; Bäuerle, Tobias imprint: Wiley, 2011 Published in: Contrast Media & Molecular Imaging, 6 (2011) 6, Seite 413-420 Language: English DOI: 10.1002/cmmi.435 ISSN: 1555-4309; 1555-4317 Origination: Footnote: Description: <jats:p>The aim of this study was the evaluation of <jats:sup>68</jats:sup>Ga‐DOTA‐E‐[c(RGDfK)]<jats:sub>2</jats:sub> as a novel PET tracer to image <jats:italic>α</jats:italic>v<jats:italic>β</jats:italic>3 and <jats:italic>α</jats:italic>v<jats:italic>β</jats:italic>5 integrins. For this purpose, DOTA‐E‐[c(RGDfK)]<jats:sub>2</jats:sub> was labeled with <jats:sup>68</jats:sup>Ga, which was obtained from a <jats:sup>68</jats:sup>Ge/<jats:sup>68</jats:sup>Ga generator, purified by solid‐phase extraction and the radiochemical purity analyzed by radio‐RP‐HPLC. <jats:sup>68</jats:sup>Ga‐DOTA‐E‐[c(RGDfK)]<jats:sub>2</jats:sub> was obtained reproducibly in radiochemical yields of 60 ± 6% and with an excellent radiochemical purity of >99%. In nude rats bearing bone metastases after injection of MDA‐MB‐231 human breast cancer cells, biodistribution studies were performed to evaluate the accumulation of the radiotracer in selected organs, blood and bone metastases 0.5, 1, 2 and 3 h post injection. A rapid uptake into the bone metastases and rapid blood clearance was observed, resulting in tumor–blood ratios of up to 26.6 (3 h post injection) and tumor–muscle ratios of up to 7.9 (3 h post injection). A blocking experiment with coinjected <jats:italic>α</jats:italic>v<jats:italic>β</jats:italic>3/<jats:italic>α</jats:italic>v<jats:italic>β</jats:italic>5 antagonist showed the tumor uptake to be receptor‐specific. In an initial <jats:italic>in vivo</jats:italic> micro PET evaluation of the tracer using the same animal model, the bone metastasis was clearly visualized. These results suggest that <jats:sup>68</jats:sup>Ga‐DOTA‐E‐[c(RGDfK)]<jats:sub>2</jats:sub> is a promising PET tracer suitable for the imaging of <jats:italic>α</jats:italic>v<jats:italic>β</jats:italic>3 and <jats:italic>α</jats:italic>v<jats:italic>β</jats:italic>5 integrins in bone metastases. This novel PET tracer should be further evaluated concerning its usefulness for early detection of bone metastases and monitoring treatment response of these lesions. Copyright © 2011 John Wiley & Sons, Ltd.</jats:p> Access State: Open Access