The successful treatment of type 2 diabetes and obesity with tirzepatide highlights the dual agonists of glucagon-like peptide-1 receptor (GLP-1R) and glucose-dependent insulinotropic peptide receptor (GIPR) as a powerful new generation of anti-diabetic drugs. However, tirzepatide and other GLP-1R/GIPR dual agonists currently in clinical development are linear peptides susceptible to proteolytic cleavage, thus preventing their uses as oral drugs. Previously, we reported the design of the proteolytically stable GLP-1R/GIPR peptide dual agonists via sidechain biaryl stapling. Although the stapled peptides exhibit improved proteolytic stability, they are still not sufficiently stable for oral delivery. Here, we report on the design and synthesis of more stable GLP-1R/GIPR dual agonists through a combined use of double biaryl stapling and α-methylation. One of the double-stapled and α-methylated peptides, DA23-BpyBpy, showed more potent and balanced dual agonist activities than tirzepatide, a half-life of 30 min in simulated intestinal fluid, and equal glucose lowering activity compared to semaglutide in oral glucose tolerance test in rodents. These potent and proteolytically stable double biaryl-stapled analogs should provide valuable lead peptides for developing oral GLP-1R/GIPR dual agonist drugs to treat diabetes and obesity. 10,17 21,28
