Presentation One-pot radiosynthesis of [18F]FEDAC as a clinically applicable PET ligand for imaging TSPO.

Kawamura, Kazunori  ,  Kumata, Katsushi  ,  Furutsuka, Kenji  ,  Shiomi, Satoshi  ,  Fujishiro, Tomoya  ,  Ryuji, Watanabe  ,  Takei, Makoto  ,  Hashimoto, Hiroki  ,  Ito, Takehito  ,  Ogawa, Masanao  ,  Igarashi, Nobuyuki  ,  Muto, Masatoshi  ,  Nengaki, Nobuki  ,  Nemoto, Kazuyoshi  ,  Ming-Rong, Zhang

Objectives: Translocator protein (18 kDa) (TSPO), a nucleus-encoded mitochondrial target transmembrane protein,has been indicated as an active participant in the modulation of mitochondrial function. PET using radiolabeled TSPOprobes has allowed non-invasive and reliable investigation of TSPO in neuropathological damages of experimentalanimals and humans. Many PET probes for TSPO imaging have been developed. Among them, [18F]FEDAC haspotent binding affinity and selectivity for TSPO [1], high signal to neuroinflammation [2], and high sensitivity andspecificity for detection of fatty liver diseases progression [3]. We had previously synthesized [18F]FEDAC by reactionof desmethyl-precursor with [18F]fluoroethyl bromide at two steps using a modified 18F-labelling synthesizerdeveloped in our institute [1-3]. In this study, we simplified the synthesis of [18F]FEDAC by direct 18F-fluorinationusing a typical 18F-labelling synthesizer to transfer the preparation of [18F]FEDAC to other institutes towardmulticenter clinical study.Methods: Tosylate-precursor for radiosynthesis of [18F]FEDAC was synthesized according to the procedures, asshown in Fig. 1. [18F]FEDAC was prepared by heating the tosylate-precursor with 18F- in DMSO at 110 ⁰C for 10-15min.Results: Tosylate-precursor of [18F]FEDAC was successfully synthesized from desmethyl-precursor. [18F]FEDACwas obtained with sufficient radioactivity and suitable quality for injection in clinical application. The synthesis of [18F]FEDAC was reproduceble to achieve >740 MBq, >300 GBq/μmol and >97% of radiochemical purity within 70 min ofan overall synthesis time. All other analytical results were in compliance with our in-house quality control andassurance specifications.Conclusions: We successfully synthesized [18F]FEDAC by fluorination of the tosylate-precursor with 18F- using onepot18F-labelling synthesizer. This radioligand will be used in clinical study.References: [1] Yanamoto K, et al (2009), Bioorg Med Chem Lett, 19, 1707-10. [2] Yui J, et al (2010), J Nucl Med, 51,1301-9. [3] Xie L, et al (2012), J Hepatol, 57, 1076-82.
21st International Symposium on Radiopharmaceutical Sciences

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