F-18 FDM may offer new oncologic PET agent

A fluorine-based PET agent on the workbench called 2-Deoxy-2-18F-fluoro-D-mannose (F-18 FDM) has been found to work similarly and potentially better than FDG for cancer imaging, especially of the brain, according to a study published July 10 in the Journal of Nuclear Medicine.

Shozo Furumoto, PhD, from the department of pharmacology, Graduate School of Medicine at Tohoku University in Sendai, Japan, and colleagues tested 18F-FDM as a potential PET agent in both in vitro and in vivo preliminary studies. Building from previous studies using various precursors, researchers prepared 4,6-O-benzylidene-3-O-ethoxymethyl-1-O-methyl-2-O-trifluoromethanesulfonyl-b-Dglucopyranoside as a primary precursor for synthesis of F-18 FDM and tested for uptake and metabolism in AH109A tumor cells using small animal PET systems.

“We successfully synthesized 18F-FDM by a nucleophilic substitution reaction in high radiochemical yield and purity,” wrote Furumoto et al. “F-18 FDM showed high accumulation in tumors, lower uptake in the brain than that of F-18 FDG, and rapid excretion from the blood, indicating promising characteristics for cancer imaging. Additionally, we elucidated (at least in part) the mechanism of cellular uptake and metabolism of F-18 FDM. F-18 FDM has almost the same excellent potential as F-18 FDG for PET in oncology, with an advantage of better imaging of brain tumors.”

F-18 FDM uptake in tumor-bearing rats was greater, about 2.17 percent injected dose per gram, in tumors than the brain, about 1.42 percent, at 60 minutes after injection. PET imaging results (quasi-standardized uptake value) were the same as FDG at about 2.4 percent, while brain uptake was found to be approximately 30 percent lower than tumor uptake.

Further studies are needed to evaluate for toxicity and radiation dose and to develop an automated method of radiosynthesis.