Targeted Optical Imaging of the Glucagonlike Peptide 1 Receptor Using Exendin-4-IRDye 800CW

Abstract

The treatment of choice for insulinomas and focal lesions in congenital hyperinsulinism (CHI) is surgery. However, intra-operative detection can be challenging. This could be overcome with intraoperative fluorescence imaging, which provides real-time lesion detection with a high spatial resolution. Here, a novel method for targeted near-infrared (NIR) fluorescence imaging of glucagon-like peptide 1 receptor (GLP-1R) positive lesions, using the GLP-1 agonist exendin-4, labeled with IRDye800CW, was examined in vitro and in vivo. Methods A competitive binding assay was performed using Chinese hamster lung (CHL) cells transfected with the GLP-1R. Tracer biodistribution was determined in BALB/c nude mice bearing subcutaneous CHL-GLP-1R xenografts. In vivo NIR fluorescence imaging of CHL-GLP-1R xenografts was performed. Localization of the tracer in the pancreatic islets of BALB/c nude mice was examined using fluorescence microscopy. Laparoscopic imaging was performed to detect the fluorescent signal of the tracer in the pancreas of mini pigs. Results Exendin-4-IRDye800CW binds the GLP-1R with an IC 50 value of 3.96 nM. The tracer accumulates in CHL-GLP-1R xenografts. Subcutaneous CHL-GLP-1R xenografts were visualized using in vivo NIR fluorescence imaging. The tracer accumulates specifically in the pancreatic islets of mice and a clear fluorescent signal was detected in the pancreas of mini pigs. Conclusion These date provide the first in vivo evidence of the feasibility of targeted fluorescence imaging of GLP-1R positive lesions. Intra-operative lesion delineation using exendin-4-IRDye800CW could benefit open as well as laparoscopic surgical procedures for removal of insulinomas and focal lesions in CHI.

Pathways of Glucagon Secretion and Trafficking in the Pancreatic Alpha Cell: Novel Pathways, Proteins, and Targets for Hyperglucagonemia

“…GLP-1 appears to mildly reduce action potentials in the alpha cell membrane at 1 mM glucose in isolated mouse alpha cells, and this effect is blocked by the GLP-1R antagonist exendin (9-39) ( 110 ), therefore suggesting the presence of GLP-1R, perhaps at a very low density, on a small proportion of alpha cells. The development of near infra-red and fluorescent analogues of GLP-1R ligands has enabled both in vivo ( 111 , 112 ) and high-resolution tissue imaging ( 113 , 114 ) of GLP-1R with high specificity, sensitivity, and reproducibility. Coupled with super-resolution microscopy, the fluorescent analog LUXendin645 revealed that 5% of alpha cells in murine islets expressed GLP-1R ( 114 ).…”

Exendin‐4 analogs in insulinoma theranostics

“…[67][68][69] We have developed a clinical grade exendin-4-IRDye800CW conjugate and shown feasibility of insulinoma targeting and imaging in mice with subcutaneous GLP-1R overexpressing Chinese hamster lung cell tumors. 70 We intent to start clinical trials in which this tracer is employed for FGS of insulinoma. To combine high resolution, high sensitivity, and deep tissue penetration, dual-labeled targeting moieties with a radionuclide and fluorophore have been developed for other theranostic applications in oncology.…”

“…A frequently used dye for fluorescence guiding purposes is IRDye800CW, which has been conjugated to multiple targeting moieties and is increasingly used for clinical FGS in various solid tumor types . We have developed a clinical grade exendin‐4‐IRDye800CW conjugate and shown feasibility of insulinoma targeting and imaging in mice with subcutaneous GLP‐1R overexpressing Chinese hamster lung cell tumors . We intent to start clinical trials in which this tracer is employed for FGS of insulinoma.…”

Differential Morphological Diagnosis of Various Forms of Congenital Hyperinsulinism in Children

“…The authors used the FLARE™ imaging system to acquire color video and near-infrared fluorescence images. Later, other suggestions were presented: Wada et al ( 58 ) – near-infrared fluorophores T700-F and T700-H; Park et al ( 59 ) – Ox61 for intraoperative imaging of neuroendocrine pancreatic tumors; and Boss et al ( 60 ) – near-infrared fluorophore exendin-4-IRDye 800CW for insulin and CHI. In our opinion, the development and implementation of clinical neuroendocrine intraoperative navigation can not only completely cure a child with CHI-F (and in some cases CHI-A), but also improve the quality of postoperative life for CHI-D patients.…”