Comparative Study Of Two Kinds Of ¹⁸ F Labeled RGD Method On The Expression Of Integrin α 3 In PET Imaging

Objective: To investigate the tumor targeting efficacy of [¹⁸F]FDG-RGD and Al¹⁸F-NOTA-RGD₂,two novel radio tracers containing Arginine-glycine-aspartic acid（RG D） peptides. By comparison of advantages and disadvantages of the two methods, it is hopeful to provide reference data for future research of ¹⁸F-labeled peptide ra diopharmaceuticals.Methods: [¹⁸F]FDG-RGD was synthesized by an aminooxy-functionalized RGD pe ptide and a [¹⁸F]FDG. Al¹⁸F-NOTA-RGD₂ was synthesized in one-step by conjugat ing NOTA-RGD₂ with ¹⁸F-AlF3.Labeling conditions, radiochemistry yield, specific a ctivity of labeling products, radiochemistry purity, stability in vitro and pharmacoki netics of final products were compared. The tumor targeting efficacy and in vivo biodistribution profile of [¹⁸F]FDG-RGD and Al¹⁸F-NOTA-RGD₂, following intrave nous injection via the tail vein, were evaluated in nude mice model bearing U87 M G glioblastoma.Results: Both[¹⁸F]FDG-RGD and Al¹⁸F-NOTA-RGD₂ could readily label RGDf K p eptide with 18 F,with a yield of about（13-15）% and（17-25）%.[¹⁸F]FDG-RGD could produce radiolabeled peptides with better specific activity, while Al¹⁸F-NOTA-RG D2 is proved to be a more time-saving method. For stability test, more than 80% of both [¹⁸F]FDG-RGD and Al¹⁸F-NOTA-RGD₂ could maintain intact in PBS or H SA within 360 min, and about 50% radiolabeled peptides could survive in vivo. T he radioactivity biodistribution did not show obvious differences.Conclusions: The synthetic process of Al¹⁸F-NOTA-RGD₂ is more efficient and le ss time cosuming. The in vitro and in vivo stability of [¹⁸F]-RGD obtained in bot h methods were excellent. But in the biodistribution pattern of radiolabeled product s,Al¹⁸F-NOTA-RGD₂ has better tumor-targeting characteristics,and it is more condu cive to clinical promotion.