Radiosynthesis and preliminary biological evaluation of N-(2-[(18)F]fluoropropionyl)-L-glutamine as a PET tracer for tumor imaging

In this study, radiosynthesis and biological evaluation of a new [(18)F]labeled glutamine analogue, N-(2-[(18)F]fluoropropionyl)-L-glutamine ([(18)F]FPGLN) for tumor PET imaging are performed. [(18)F]FPGLN was synthesized via a two-step reaction sequence from 4-nitrophenyl-2-[(18)F]fluoropropionate ([(18)F]NFP) with a decay-corrected yield of 30 ± 5% (n=10) and a specific activity of 48 ± 10 GBq/μmol after 125 ± 5 min of radiosynthesis. The biodistribution of [(18)F]FPGLN was determined in normal Kunming mice and high uptake of [(18)F]FPGLN was observed within the kidneys and quickly excreted through the urinary bladder. In vitro cell experiments showed that [(18)F]FPGLN was primarily transported by Na(+)-dependent system X(AG)(−) and was not incorporated into proteins. [(18)F]FPGLN displayed better stability in vitro than that in vivo. PET/CT studies revealed that intense accumulation of [(18)F]FPGLN were shown in human SPC-A-1 lung adenocarcinoma and PC-3 prostate cancer xenografts. The results support that [(18)F]FPGLN seems to be a possible PET tracer for tumor imaging.