Radiosynthesis and Preliminary Biological Evaluation of 18F-Fluoropropionyl-Chlorotoxin as a Potential PET Tracer for Glioma Imaging.

PURPOSES: Chlorotoxin can specifically bind to matrix metalloproteinase 2 (MMP-2), which are overexpressed in the glioma. In this work, radiosynthesis of [18F]-fluoropropionyl-chlorotoxin ([18F]-FP-chlorotoxin) as a novel PET tracer was investigated, and biodistribution in vivo and PET imaging were performed in the C6 glioma model.

PROCEDURES: [18F]-FP-chlorotoxin was prepared from the reaction of chlorotoxin with [18F]-NFB (4-nitrophenyl 2-[18F]-fluoropropionate), which was synthesized from multistep reactions. Biodistribution was determined in 20 normal Kunming mice. Small-animal PET imaging with [18F]-FP-chlorotoxin was performed on the same rats bearing orthotopic C6 glioma at different time points (60 min, 90 min, and 120 min) after injection and compared with 2-deoxy-2-[18F] fluoro-D-glucose ([18F]-FDG).

RESULTS

[18F]-FP-Chlorotoxin was successfully synthesized in the radiochemical yield of 41% and the radiochemical purity of more than 98%. Among all the organs, the brain had the lowest and stable uptake of [18F]-FP-chlorotoxin, while the kidney showed the highest uptake. Compared with [18F]-FDG, a low uptake of [18F]-FP-chlorotoxin was detected in normal brain parenchyma and a high accumulation of [18F]-FP-chlorotoxin was found in the gliomas tissue. The glioma to normal brain uptake ratio of [18F]-FP-chlorotoxin was higher than that of [18F]-FDG. Furthermore, the uptake of [18F]-FP-chlorotoxin at 90 min after injection was better than that at 60 min after injection.

CONCLUSIONS

Compared with [18F]-FDG, [18F]-FP-chlorotoxin has a low and stable uptake in normal brain parenchyma. [18F]-FP-Chlorotoxin seems to be a potential PET tracer with a good performance in diagnosis of the glioma.