In vitro and in vivo characterization of a novel long-acting GLP-1 receptor agonist, exendin-4–Fc fusion protein

Abstract

Exendin-4 (Ex-4), one of the important glucagon-like peptide-1 receptor (GLP-1R) agonists, has proven to be an effective antidiabetic agent for type 2 diabetes (T2D). However, its therapeutic potential is limited due to its short half-life (t_1/2), which is subcutaneously administered twice daily. The aim of this study is to develop a safe, efficacious and longer acting potential anti-diabetic agent. The bioactivity of (Ex-4)₂–Fc was examined in U₂OS cells and we used molecular docking software to test the stability of the (Ex-4)₂–Fc/GLP-1 receptor complexes. The pharmacokinetics of (Ex-4)₂–Fc was studied in male Sprague-Dawley (SD) rats and the pharmacodynamics was assessed in various mouse models. The bioactivity of (Ex-4)₂–Fc was over 10-fold higher than that of Ex-4–Fc in vitro and the stability of the (Ex-4)₂–Fc/GLP-1 receptor complexes was better than that of the Ex-4–Fc/GLP-1 receptor complexes. The pharmacokinetics of (Ex-4)₂–Fc showed that it had a more than 200-fold prolongation in plasma half-life compared with that of Ex-4, which was 122 h and 0.56 h, respectively. The treatment with (Ex-4)₂–Fc every 6 days, compared to the vehicle control, effectively reduced body weight, decreased food intake, and improved glucose metabolism in high-fat-diet induced obesity (DIO) mice, leptin-deficient ob/ob and leptin receptor-defective db/db mice. Our studies suggest that (Ex-4)₂–Fc retains the bioactivity of the GLP-1 receptor agonist with a prolonged half-life in vivo, providing a promising drug candidate for the treatment of type 2 diabetes.