Obesity is a chronic, multifactorial disease that has reached epidemic status. The glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) is a key therapeutic target to achieve weight loss and glycemic control in obesity and type 2 diabetes mellitus. Tirzepatide and retatrutide, the latest generation of GLP-1-incorporating multi-agonists, target multiple receptors in complementary systems to achieve marked and sustained weight loss. However, the associated gastrointestinal (GI) side effects (e.g., nausea, vomiting, diarrhea, abdominal pain) that often hinder patient compliance underscore a remaining need for therapies with better tolerability. GEP44, a novel, monomeric, chimeric peptide structurally based on native GLP-1, the GLP-1RA exendin-4 (Ex-4), and the gut-derived hormone peptide YY3-36 (PYY3-36), is an agonist at the GLP-1R and multiple neuropeptide Y (NPY) receptors. This review summarizes the design rationale for GEP44 and preclinical evidence supporting its beneficial metabolic effects and tolerability. Like GLP-1, PYY3-36 is associated with decreased food intake (FI), and co-administration of GLP-1RA and PYY3-36 elicits synergistic food intake (FI)- and body weight (BW)-reducing effects with similar or enhanced blood glucose (BG)-lowering effects. Studies examining the efficacy of GEP44 to promote weight loss and improve glucoregulation in lean vs. diet-induced obese rodents report that peripheral administration generally decreases BW, FI, and insulin resistance and increases EE at equivalent or greater magnitudes than those observed with single GLP-1RAs in a GLP-1R-dependent manner with improved GI tolerability. These beneficial actions reflect GEP44's potential to expand the mechanistic scope of anti-obesity medications.
