A Phase 2 Randomized Trial of Retatrutide in People with Obesity and MASLD

Metabolic-associated steatotic liver disease (MASLD, formerly NAFLD) affects roughly a quarter of the global adult population and currently has very few effective pharmacological treatments. This Phase 2 trial by Sanyal, Kaplan, Frias, and colleagues, published in the New England Journal of Medicine, evaluated whether retatrutide's unique triple-agonist mechanism could address this unmet medical need.

The study was a substudy of the larger Phase 2 obesity trial, specifically analyzing participants who had MASLD at baseline (liver fat content of 10% or more on MRI-proton density fat fraction). Participants received various doses of retatrutide or placebo, with liver fat assessed by MRI at baseline and at 48 weeks.

The results were remarkable. At the highest dose, up to 90% of participants achieved normalization of liver fat content (defined as less than 5%) at 48 weeks. This resolution rate dramatically exceeds results seen with other investigational and approved therapies for MASLD. Liver fat reductions were dose-dependent and correlated with overall weight loss, though the magnitude of liver fat improvement appeared disproportionately large relative to weight change alone.

The glucagon receptor agonism in retatrutide is believed to be a key driver of these hepatic benefits, as glucagon signaling directly promotes hepatic lipid oxidation and reduces de novo lipogenesis in the liver. Combined with GLP-1-mediated appetite suppression and GIP-mediated metabolic improvements, this triple mechanism appears uniquely suited to addressing the liver fat accumulation that underlies MASLD. If confirmed in Phase 3 trials, retatrutide could become the first highly effective treatment for a disease that threatens to become the leading cause of liver transplantation.