Radiosynthesis and evaluation of an 18 F-labeled silicon containing exendin-4 peptide as a PET probe for imaging insulinoma

Analogues of exendin-4 have been radiolabeled for imaging the glucagon-like peptide type 1 receptors (GLP-1R) which are overexpressed in insulinoma. The aim of this research was to synthesize an F-labeled silicon containing exendin-4 peptide ( F- ) and to evaluate its in vitro and behavior in CHL-GLP-1 receptor positive tumor-bearing mice. F-labeled silicon containing exendin-4 peptide ( F- ) was prepared via one-step nucleophilic substitution of a silane precursor with F-fluoride in the presence of acetic acid and K222. F- was then administered to tumor-bearing mice for PET imaging and biodistribution experiments. F- was produced in a radiochemical yield (decay corrected) of 1.5% and a molar activity of max. 16 GBq/μmol. The GLP-1R positive tumors were clearly visualized by PET imaging. Biodistribution studies showed reduced uptake of F- in the kidneys compared to radiometal labeled exendin-4 derivatives. The radiotracer showed specific tumour uptake which remained steady over 2 h. This exendin-4 analogue, F- , is a potential probe for imaging GLP-1R positive tumors.