FGF21

Class

FGF21 analog/agonist

Notes

original target text: FGF21 pathway

FGF21 (fibroblast growth factor 21) is a hormone produced mainly by the liver that regulates whole-body energy and lipid metabolism. Unlike most fibroblast growth factors, which act locally, FGF21 circulates in the bloodstream and signals to distant tissues, including fat, muscle, and the brain, by binding a receptor complex made up of an FGF receptor and an obligatory co-receptor called beta-klotho. Through this pathway, FGF21 increases insulin sensitivity, promotes energy expenditure, and reduces the accumulation of fat in the liver and elsewhere. Because natural FGF21 protein is unstable and cleared quickly from the body, engineered FGF21 analogs are designed to mimic its receptor-activating function while lasting longer in circulation, making sustained dosing feasible. This class of agents is being explored for metabolic diseases characterized by excess liver fat, insulin resistance, and abnormal lipid handling, most notably fatty liver conditions that can progress to inflammation and scarring, as well as broader metabolic dysfunction linked to obesity and type 2 diabetes. The biological rationale for targeting this pathway is that it addresses multiple facets of metabolic disease simultaneously, rather than a single downstream marker, by acting upstream on the hormonal signal that coordinates fat and glucose handling across organs.