Development and Characterization of a Humanized GLP-1 Receptor Mouse Model for the Evaluation of Small-Molecule GLP1R Agonists

Introduction and Objective: Injectable peptide-based GLP-1 receptor agonists (GLP1RAs) have emerged as effective therapies for obesity and diabetes. However, peptide-based GLP1RAs present challenges related to patient compliance and scalable production. Small-molecule GLP1RAs offer advantages in oral administration but exhibit poor activity on rodent GLP1R, complicating preclinical pharmacodynamic assessments. To improve translational relevance, we developed a humanized GLP1R (hGLP1R) mouse model using CRISPR-Cas9 gene editing, replacing the endogenous murine receptor with the human form. Methods: The hGLP1R mouse model was generated by replacing the murine GLP1R with the human GLP1R using CRISPR-Cas9 gene editing. Immunohistochemical analyses confirmed hGLP1R expression in pancreatic beta cells, brain stem, and hypothalamus. Pharmacological characterization included single-dose and chronic treatment studies evaluating the metabolic effects of semaglutide (peptide GLP1RA) and orforglipron (small-molecule GLP1RA) in both lean and DIO hGLP1R and wt mice. Additionally, 3D whole-brain imaging was performed to assess central target engagement. Results: Single-dose studies in lean hGLP1R mice showed comparable efficacy of semaglutide and orforglipron on body weight, food intake, glucose tolerance, and conditioned taste aversion. Semaglutide, but not orforglipron, also demonstrated metabolic effects in lean wt mice. Chronic semaglutide and orforglipron treatment significantly reduced body weight, whole-body fat mass, and food intake in DIO hGLP1R mice, with no effect of orforglipron observed in DIO wild-type mice. 3D whole-brain imaging confirmed activation of canonical appetite-regulating brain regions by both semaglutide and orforglipron in hGLP1R mice. Conclusion: These findings validate the Gubra hGLP1R mouse as a relevant preclinical model to advance preclinical development of small-molecule GLP1RAs for the treatment of obesity and related metabolic disorders. Disclosure: N. Sonne: None. K. Abney: Research Support; TERNS Pharmaceuticals. M. Feigh: None. H.H. Hansen: None. C. Jones: Employee; TERNS Pharmaceuticals. O. Osborn: None. M.L. Riis: None. S.E. Pors: None. M. Cavalera: None. L.F. Zachariassen: None. M. Tozzi: None.