The therapeutic potential of FGF21 in metabolic diseases: from bench to clinic

Fibroblast growth factor 21 (FGF21) is a stress-inducible hormone that has important roles in regulating energy balance and glucose and lipid homeostasis through a heterodimeric receptor complex comprising FGF receptor 1 (FGFR1) and β-klotho. Administration of FGF21 to rodents or non-human primates causes considerable pharmacological benefits on a cluster of obesity-related metabolic complications, including a reduction in fat mass and alleviation of hyperglycaemia, insulin resistance, dyslipidaemia, cardiovascular disorders and non-alcoholic steatohepatitis (NASH). However, native FGF21 is unsuitable for clinical use owing to poor pharmacokinetic and biophysical properties. A large number of long-acting FGF21 analogues and agonistic monoclonal antibodies for the FGFR1–β-klotho receptor complexes have been developed. Several FGF21 analogues and mimetics have progressed to early phases of clinical trials in patients with obesity, type 2 diabetes mellitus and NASH. In these trials, the primary end points of glycaemic control have not been met, whereas substantial improvements were observed in dyslipidaemia, hepatic fat fractions and serum markers of liver fibrosis in patients with NASH. The complexity and divergence in pharmacology and pathophysiology of FGF21, interspecies variations in FGF21 biology, the possible existence of obesity-related FGF21 resistance and endogenous FGF21 inactivation enzymes represent major obstacles to clinical implementation of FGF21-based pharmacotherapies for metabolic diseases. Fibroblast growth factor 21 (FGF21) confers considerable pharmacological benefits on a cluster of obesity-related metabolic complications when administered to preclinical models. This Review discusses FGF21 analogues and mimetics and highlights their efficacy in preclinical models and clinical trials. The challenges in developing FGF21-based therapeutics are also considered. Key points The discovery of fibroblast growth factor 21 (FGF21) as a potent agent for treatment of obesity and type 2 diabetes mellitus in animals has inspired the development of engineered FGF21 analogues and mimetics with improved potency and pharmacokinetic profiles. The multiple metabolic effects of FGF21 are mediated by both its central and peripheral actions, and by its fine-tuning of inter-organ metabolic crosstalk. In individuals with obesity and type 2 diabetes mellitus, FGF21 analogues alleviate dyslipidaemia and increase adiponectin levels, but have minimal effects on gly