Evaluation of Sulfone-Labeled Amino Acid Derivatives As Potential PET Agents for Cancer Imaging.

INTRODUCTION:As one of the most important and frequently used molecular imaging techniques in the clinic, positron emission tomography (PET) features high sensitivity and specificity, which generally involves the use of PET contrast agents. Despite the exceptional promise, the availability of novel PET agents could limit its application and there is a clear need to develop new PET agents to improve our understanding of targets of interest and increase the diagnostic specificity.METHODS:Based on the fact that amino acid transport and protein anabolism are increased in tumor tissues, a series of 18F-labeled amino acid analog was labeled with 18F by using [18F]fluoro-4-(vinylsulfonyl)benzene as the radionuclide linker. The obtained probes were subjected to in vitro and in vivo evaluation, including stability, cell line transport channel specificity, PET/CT imaging on tumor and inflammation bearing mice, and biodistribution.RESULTS:Our data shows that [18F]2a had moderate decay corrected labeling yield (>42 %) and high radiochemical purity (>99 %). When tested in vivo, the uptake of [18F]2a was 1.5 ± 0.2%ID/g in NCI-H1975 tumors and 1.1 ± 0.2%ID/g in inflammatory tissues. In contrast, the values for [18F]FDG were 5.7 ± 0.2%ID/g and 4.8 ± 0.1%ID/g, respectively. The inflammatory lesion-to-muscle contrast is 2.4 for [18F]2a, which is 3.0 for [18F]FDG.CONCLUSION:Clearly, [18F]2a hold the great potential for cancer imaging. Its application in distinguishing tumor from inflammatory lesion would still need to be investigated further.