A new single‑piece peptide that hits both GLP‑1 and MC4 receptors (called KCEM1) cut food intake and weight in obese rats just as well as the popular drugs semaglutide and tirzepatide, and it also improved blood sugar control and reduced liver fat and inflammation more than those drugs. The work is still in animals, so it isn’t ready for human use yet, but it shows that combining these two pathways might give extra metabolic benefits beyond current GLP‑1‑only meds.

Obesity and its sequelae cause significant morbidity and mortality worldwide. Current glucagon-like peptide-1 (GLP-1) receptor agonist-based treatments have significant side-effects associated with high rates of treatment discontinuation. Such concerns are greater still in children and adolescents. Thus, there remains a clinical unmet need to develop obesity and/or T2D mellitus therapies with significantly improved tolerability. Herein, we examined a polypharmacy approach combining melanocortin (MC) 4-, and GLP-1-receptor agonism in a single monomeric peptide based on α-MSH and Exendin-4 to bind and stimulate different peptide receptors in vitro, and to drive reductions in body weight and food intake in up to 7 weeks of treatment in comparison to semaglutide and tirzepatide as standard of care positive controls in diet-induced obese rats. Despite the monomeric peptide GLP-1-/MC4-receptor multiple agonist (KCEM1) being a non-lipidated, weaker GLP-1R agonist compared to semaglutide and tirzepatide, reductions in calorie intake and body weight were similar in all three groups after daily subcutaneous injections of the three peptides. In addition, KCEM1 offered superior glycemic control during glucose tolerance testing. In gene expression analyses, KCEM1, but not semaglutide or tirzepatide, significantly increased expression of glucose transporter 4 (GLUT4) and key glycolysis enzyme Pgk1 in skeletal muscle, while it reduced genetic markers of inflammation in different tissues, including inflammatory markers IL-6 and TNF-α in liver tissue. Furthermore, KCEM1 lowered hepatic lipid content and improved metabolic dysfunction-associated steatohepatitis (MASH) scoring. Overall, these data extend emerging concepts around the use of multi-receptor polypharmacy to treat metabolic syndrome.