KYLO-0603, a novel liver-targeting, thyroid hormone receptor-β agonist for the treatment of MASH

Metabolic dysfunction–associated steatohepatitis (MASH) is a progressive liver disease associated with liver-related complications and death. Kylo-0603 is a novel agonist for the thyroid hormone receptor β (THR-β) that has been developed by merging the structures of three acetylgalactosamine (GalNAc)-modified ASPGR ligands with a triiodothyronine (T3) analog. This unique design allows for both THR-β activation and targeted delivery to hepatocytes, significantly reducing the risk of adversed effects related to increased systemic thyroid hormone-like effects. Additionally, it effectively lowers serum cholesterol by as much as 69.2% and low-density lipoprotein cholesterol (LDL-C) levels by up to 88.2% in the MASH mouse model. Meanwhile, Kylo-0603 was shown to reduce steatosis by up to 1.3 points (P < 0.001), inflammation by 1.8 points (P < 0.0001), and ballooning by 0.8 points (P < 0.01). The non-alcoholic steatohepatitis (NASH) activity score (NAS) decreased by up to 3.7 points (P < 0.0001), and the fibrosis score dropped by 0.6 points (P < 0.05). These findings suggest that Kylo-0603 is effective in enhancing liver tissue NASH status and inhibiting fibrosis progression. In summary, Kylo-0603, as a highly both tissue and target selective and low-toxicity THR-β agonist, shows significant promise for treating MASH and is likely to emerge as a new therapeutic option for patients with this condition.