Lead-guided prodrug development of small molecules as GLP-1R agonists.

The glucagon-like peptide-1 receptor (GLP-1R) is a well-established target for treating obesity and T2DM. To date almost all approved therapies targeting this receptor are peptide-based. The small-molecule GLP-1R agonist danuglipron, developed by Pfizer, demonstrated strong GLP-1 agonistic properties, reductions in body weight and improved glycemic control. Yet, its short duration of action, gastrointestinal side effects, and a potential case of drug-induced liver disease led to discontinuation in clinical trials. In this study, we designed and synthesized a series of acid and ester analogs of danuglipron, incorporating diverse substitution patterns and deliberate modifications, including variable substitutions and key moiety replacements. The corresponding acid forms retained activity comparable to the lead compound and the peptide drug tirzepatide. Notably, the ester compound 4 exhibited a controlled and sustained conversion to its active metabolite 4a in human plasma, as confirmed by mass spectrometry and in vitro GLP-1R activity assays. These findings suggest that the ester derivatives might represent a potential approach for modulating the pharmacokinetic properties of these compounds, and the resulting prodrugs could potentially provide more sustained systemic exposure and possibly offer safety-related advantages; however, these hypotheses require further validation through appropriate in vivo pharmacokinetic and toxicological studies.