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

We have previously reported that N -(2-[ 18 F]fluoropropionyl)- L -methionine ([ 18 F]FPMET) selectively accumulates in tumors. However, due to the poor pharmacokinetics of [ 18 F]FPMET in vivo , the potential clinical translation of this observation is hampered. In this study, we rationally designed and synthesized [ 18 F] or [ 11 C]labeled N -position L-glutamic acid analogues for tumor imaging. N -(2-[ 18 F]fluoropropionyl)- L -glutamic acid ([ 18 F]FPGLU) was synthesized with a 30±10% (n = 10, decay-corrected) overall radiochemical yield and a specific activity of 40±25 GBq/μmol (n = 10) after 130 min of radiosynthesis. In vitro cell experiments showed that [ 18 F]FPGLU was primarily transported through the X AG – system and was not incorporated into protein. [ 18 F]FPGLU was stable in urine, tumor tissues, and blood. We were able to use [ 18 F]FPGLU in PET imaging and obtained high tumor to background ratios when visualizing tumors tissues in animal models.