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G. Reischl, Achim Blocher, Rongqing Wei, Walter Ehrlichmann, Matthias Kuntzsch, Christoph Solbach, Bernhard M. Dohmen, Hans-Jürgen Machulla
Simplified, automated synthesis of 3′-[18F]fluoro-3′-deoxy-thymidine ([18F]FLT) and simple method for metabolite analysis in plasma
Keywords: [18F]FLT, PET, Tumor proliferation, Anhydrothymidine, Metabolite analysis
3′[18F]Fluoro-3′-deoxy-thymidine ([18F]FLT) (III) has been discussed to be a promising tracer for assessing tumor proliferation. In order to perform clinical studies for evaluating [18F]FLT a simplified labeling procedure was developed using 2,3′-anhydrothymidine with benzoyl as a protecting group in the 5′-position (I). In DMSO the labeling yield was 46% at 160 °C in 10 min. Hydrolysis was efficiently performed with 0.25% NaOH at room temperature within 10 min. The labeling procedure was transferred to a remote controlled synthesis module allowing the production of [18F]FLT in high activities. The overall radiochemical yield was 18.1±5.4% (n = 55) with absolute yields of 9.2±2.6 GBq of [18F]FLT at EOS ready for injection (60 min after EOB; irradiation parameters: 35 μA, 60 min) and specific activities of 100-220 GBq/μmol. A convenient cartridge method for metabolite analysis was developed and validated versus HPLC showing that after 90 min 69.0±7.0% of the radioactivity in plasma (less than 20% of initial radioactivity) was unchanged [18F]FLT (26 patients with various tumors).
Radiochimica Acta, Oldenbourg Wissenschaftsverlag
Print ISSN: 0033-8230
Volume: 94, 08/2006
Pages: 447 - 451