First-in-human assessment of the novel LAT1 targeting PET probe ¹⁸F-FIMP

In the first-in-human PET study, we evaluated the biodistribution and tumor accumulation of the novel PET probe, (S)-2-amino-3-[3-(2-¹⁸F-fluoroethoxy)-4-iodophenyl]-2-methylpropanoic acid (¹⁸F-FIMP), which targets the tumor-related L-type amino acid transporter 1 (LAT1), and compared it with L-[methyl-¹¹C]methionine (¹¹C-MET) and 2-Deoxy-2-¹⁸F-fluoro-D-glucose (¹⁸F-FDG). ¹⁸F-FIMP biodistribution was revealed by whole-body and brain scans in 13 healthy controls. Tumor accumulation of ¹⁸F-FIMP was evaluated in 7 patients with a brain tumor, and compared with those of ¹¹C-MET and ¹⁸F-FDG. None of the subjects had significant problems due to probe administration, such as adverse effects or abnormal vital signs. ¹⁸F-FIMP was rapidly excreted from the kidneys to the urinary bladder. There was no characteristic physiological accumulation in healthy controls. ¹⁸F-FIMP PET resulted in extremely clear images in patients with suspected glioblastoma compared with ¹¹C-MET and ¹⁸F-FDG. ¹⁸F-FIMP could be a useful novel PET probe for LAT1-positive tumor imaging including glioblastoma.