Background: GLP-1 receptor peptide agonists have revolutionized type 2 di-abetes mellitus and obesity treatment, primarily through injection-based therapies. Small-molecule GLP-1 receptor agonists allow oral administration, but none are clini-cally established. Pfizer's danuglipron and lotiglipron, presented in 2018-2019, were "first-in-class" drug candidates, becoming prototypes for "next-in-class" drug develop-ment. Objective: This review summarizes "next-in-class" GLP-1 receptor agonists developed, identifying different relationships between the molecular structure and functional activi-ty of agonists. Methods: Patents containing danuglipron- and lotiglipron-like agonists from January 2021 to July 2024 were browsed in databases, such as Espacenet and Google Patents, using specified keywords. Over 5,000 compounds from 67 patent publications were an-alyzed. Results: Our analysis identified some key general SAR trends. The presence of a car-boxyl group leads to highly active agonists, but replacing it with bioisosteric analogs may improve the ADME profile of the target compounds. The introduction of specific privileged fragments, as well as the replacement of 1H-benzo[d]imidazole nucleus or (S)-oxetan-2-ylmethyl substituent in the prototype structure with bioisosteric heterocy-cles, may be viable approaches. The replacement of 1,4-disubstituted piperidine linked with its (S)-2-methyl-substituted homologue or O, N-disubstituted piperidin-4-ol may also result in highly potent agonists. Additionally, the classic 2,4-EWG-disubstituted benzyl alcohol residue allows significant variability. Conclusion: Despite the limited clinical success of danuglipron and lotiglipron, as well as the inherent problems associated with the complex nature of GLP-1R signaling, the current state of research and the abundance of novel, promising chemotypes of highly potent compounds suggest that approved GLP-1R agonists may emerge in the coming years.

Glucagon-like peptide-1 (GLP-1) is an incretin hormone secreted by intestinal endocrine L cells that activates the GLP-1 receptor (GLP-1R), leading to glucose-dependent insulin secretion and suppression of glucagon release. In recent years, GLP-1R agonists (GLP-1RAs) have become one of the leading therapeutic options for the treatment of type 2 diabetes mellitus; however, for a long time clinically approved GLP-1RAs were limited to peptide drugs unsuitable for oral administration. The discovery of the “first-in-class” small molecule agonist danuglipron in 2018 demonstrated the feasibility of orally available GLP-1RAs and stimulated the development of numerous danuglipron-like compounds, some of which showed increased efficacy over the prototype. In this study, we report the design and synthesis of novel GLP-1RAs based on a regioisomeric danuglipron scaffold, 1H-benzo[d]imidazole-5-carboxylic acid. A series of 35 compounds was synthesized and evaluated in vitro for cytotoxicity and GLP-1R agonistic activity using a cAMP accumulation assay. A potent lead compound 12r (pEC₅₀ = 7.72, pCC₅₀ < 3.60) was found which is a close structural analog of danuglipron with reduced cytotoxicity and excellent selectivity over two other class B GPCRs, including GCGR and GIPR. Despite decreased potency compared to danuglipron, the obtained results hold promise for further optimization and provide valuable structure–activity relationship insights.