DOI: 10.1186/s41181-017-0036-6Pages: 1-11

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

1. ETH Hönggerberg, ETH Zurich, Center for Radiopharmaceutical Sciences (CRS) of ETH, PSI and USZ, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences

2. Center for Radiopharmaceutical Sciences (CRS), Research Department Biology and Chemistry, Paul Scherrer Institut

Correspondence to:
Martin Béhé
Tel: +41 (0) 56 310 2817
Email: martin.behe@psi.ch

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Abstract

Background

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 18F–labeled silicon containing exendin-4 peptide (18F-2) and to evaluate its in vitro and in vivo behavior in CHL-GLP-1 receptor positive tumor-bearing mice.

18F–labeled silicon containing exendin-4 peptide (18F-2) was prepared via one-step nucleophilic substitution of a silane precursor with 18F–fluoride in the presence of acetic acid and K222. 18F-2 was then administered to tumor-bearing mice for PET imaging and ex vivo biodistribution experiments.

Results

18F-2 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 18F-2 in the kidneys compared to radiometal labeled exendin-4 derivatives. The radiotracer showed specific tumour uptake which remained steady over 2 h.

Conclusions

This exendin-4 analogue, 18F-2, is a potential probe for imaging GLP-1R positive tumors.

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  • Accepted: Dec 14, 2017
  • Online: Jan 2, 2018

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