PET Imaging of Dual GLP-1R and GIPR Targeting with [18F]AlF-NOTA-Asp2-Tirzepatide

Abstract Tirzepatide is a clinical dual GLP-1R and GIPR agonist for type 2 diabetes and obesity, and non-invasive approaches to assess its in vivo biodistribution and systemic toxicity in living animals remain limited. Both receptors also serve as potential targets for neuroendocrine tumor imaging, and dual-target PET probes for simultaneous GLP-1R and GIPR detection are still lacking. Herein, we developed a novel PET probe [18F]AlF-NOTA-Asp2-tirzepatide via structural modification of tirzepatide. This probe successfully visualized the in vivo distribution of tirzepatide, which was primarily eliminated through the renal system. The C20 fatty diacid moiety caused elevated uptake in the heart, liver and blood due to enhanced albumin binding. In vitro assays verified its reliable GLP-1R and moderate GIPR binding affinity. Persistent tumor accumulation was observed in INS-1 and A549-GIPR xenografts, allowing effective tumor visualization. In summary, [18F]AlF-NOTA-Asp2-tirzepatide features facile radiolabeling and enables the clear visualization of tirzepatide in vivo, along with favorable dual-targeting performance, while excessive non-target uptake still needs to be optimized for further clinical translation.