Generation and characterisation of a humanised GLP-1 receptor mouse model for translational drug development.

BACKGROUND: Injectable peptide-based glucagon-like peptide-1 receptor (GLP1R) agonists (GLP1RAs) are effective treatments for obesity and diabetes but are limited by patient compliance and scalability challenges. In contrast, non-peptide small-molecule GLP1RAs offer the advantage of oral delivery but are relatively inactive at the rodent GLP1R, limiting their utility in preclinical pharmacodynamic studies. This study aimed to bridge the translational gap by engineering and thoroughly validating a humanised GLP-1 receptor (hGLP1R) mouse model that more accurately recapitulates human receptor pharmacology, thereby enhancing its utility for preclinical drug development. METHODS: The hGLP1R mouse was generated via CRISPR-Cas9-mediated replacement of the endogenous murine Glp1r gene with the human orthologue. The hGLP1R mouse model was pharmacologically characterised using peptide (semaglutide) and small-molecule (orforglipron) GLP1RAs in lean and diet-induced obese (DIO) hGLP1R and wild-type (WT) mice. FINDINGS: Immunohistochemistry confirmed expression of the human GLP1R and complete absence of the endogenous murine GLP1R in pancreatic β-cells and key appetite-regulatory brain regions of hGLP1R mice. In lean hGLP1R mice, both semaglutide and orforglipron significantly reduced body weight and food intake, improved glucose tolerance, and induced taste aversion. CNS response profiles were evaluated using high-resolution 3D whole-brain imaging, revealing overlapping c-Fos activation patterns for both agonists. In DIO hGLP1R mice, chronic administration of either compound produced robust reductions in body weight, food intake and plasma lipids. Notably, orforglipron was inactive in WT mice, which responded only to semaglutide. INTERPRETATION: These findings establish the hGLP1R mouse as a robust and translational platform for advancing the discovery and evaluation of novel small-molecule GLP1RAs targeting obesity and related metabolic diseases. FUNDING: This research was funded by Gubra A/S and Terns Pharmaceuticals, Inc.; there was no external funding.