Tumour imaging by Positron Emission Tomography using fluorinase generated 5-[18F]fluoro-5-deoxyribose as a novel tracer

Abstract Introduction 5-[ 18 F]Fluoro-5-deoxyribose ([ 18 F]FDR) 3 was prepared as a novel monosaccharide radiotracer in a two-step synthesis using the fluorinase, a C-F bond forming enzyme, and a nucleoside hydrolase. The resulting [ 18 F]FDR 3 was then explored as a radiotracer for imaging tumours (A431 human epithelial carcinoma) by positron emission tomography in a mice model. Methods 5-[ 18 F]Fluoro-5-deoxyribose ([ 18 F]FDR) 3 , was prepared by incubating S -adenosyl-L-methionine (SAM) and [ 18 F]fluoride with the fluorinase enzyme, and then incubating the product of this reaction, [ 18 F]-5'-fluoro-5'-deoxadenosine ([ 18 F]FDA) 2 , with an adenosine hydrolase to generate [ 18 F]FDR 3 . The enzymes were freeze-dried and were used on demand by dissolution in buffer solution. The resulting [ 18 F]FDR 3 was then administered to four mice that had tumours induced from the A431 human epithelial carcinoma cell line. Results The tumour (A431 human epithelial carcinoma) bearing mice were successfully imaged with [ 18 F]FDR 3 . The radiotracer displayed good tumour imaging resolution. A direct comparison of the uptake and efflux of [ 18 F]FDR 3 with 2-[ 18 F]fluoro-2-deoxyglucose ([ 18 F]FDG) was made, revealing comparative tumour uptake and imaging potential over the first 10–20 min. The study revealed however that [ 18 F]FDR 3 does not accumulate in the tumour as efficiently as [ 18 F]FDG over longer time periods. Conclusions [ 18 F]FDR 3 can be rapidly synthesised in a two enzyme protocol and used to image tumours in small animal models.