Radiosynthesis and Biological Evaluation of N- [18F]Labeled Glutamic Acid as a Tumor Metabolic Imaging Tracer

We have previously reported that N-(2-[18F]fluoropropionyl)-L-methionine ([18F]FPMET) selectively accumulates in tumors. However, due to the poor pharmacokinetics of [18F]FPMET in vivo, the potential clinical translation of this observation is hampered. In this study, we rationally designed and synthesized [18F] or [11C]labeled N-position L-glutamic acid analogues for tumor imaging. N-(2-[18F]fluoropropionyl)-L-glutamic acid ([18F]FPGLU) was synthesized with a 30610 % (n = 10, decay-corrected) overall radiochemical yield and a specific activity of 40625 GBq/mmol (n = 10) after 130 min of radiosynthesis. In vitro cell experiments showed that [18F]FPGLU was primarily transported through the XAG – system and was not incorporated into protein. [18F]FPGLU was stable in urine, tumor tissues, and blood. We were able to use [18F]FPGLU in PET imaging an