Synthesis and evaluation of 18F-PTTCO-Cys40-Exendin-4 for PET imaging of ectopic insulinomas in rodents.

A major limitation in the development of radiolabeled Exendin-4 analogues (short half-life isotopes) is an inability to efficiently and rapidly separate final products from precursors. This is important as lack of purity in the final product decreases probe efficiency. The purpose of this study was to develop a method to prepare the high-purity imaging reagent [18F] PTTCO-Cys40-Exendin-4. To accomplish this, magnetic TCO-beads were incubated with the crude product to remove unlabeled Exendin-4. In rodents pre-treatment with purified [18F] PTTCO-Cys40-Exendin-4 (~1.85 MBq) allowed precise microPET imaging of ectopic insulinomas. Moreover, analogue uptake was successfully blocked by administering non-labelled "cold" Exendin-4. Biodistribution data revealed that [18F] PTTCO-Cys40-Exendin-4 accumulated specifically in GLP-1R-enriched insulinomas in mice, confirming results obtained using miroPET. Investigation of [18F] PTTCO-Cys40-Exendin-4 as a tracer to image portal vein-transplanted pancreatic islets is proceeding in animals. Copyright © 2020 Elsevier Inc. All rights reserved.

Citation

Junfeng Li, Jiangling Peng, Wei Tang, Jeffrey Rawson, Johann Karunananthan, Min Jung, Yuelong Ma, John E Shively, Fouad Kandeel. Synthesis and evaluation of 18F-PTTCO-Cys40-Exendin-4 for PET imaging of ectopic insulinomas in rodents. Bioorganic chemistry. 2020 May;98:103718

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PMID: 32171991

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