Long-acting STK25 antisense oligonucleotide as a therapeutic candidate for MASLD

Metabolic dysfunction–associated steatotic liver disease (MASLD) is the most prevalent chronic liver disorder worldwide and a leading cause of liver-related morbidity. Insulin resistance and hepatic lipid metabolism dysfunction are recognized as central pathological mechanisms, yet no therapy is currently approved specifically for MASLD. Antisense oligonucleotides (ASOs) are single-stranded nucleotide drugs with high target specificity and long-lasting activity, making them well suited for chronic metabolic diseases. Here, we describe a novel ASO candidate targeting serine/threonine kinase 25 (STK25), a lipid droplet–associated kinase implicated in MASLD pathogenesis. In three human cell lines, the ASO (c337) robustly reduced STK25 expression. For in vivo validation, we generated Gc337 by GalNAc conjugation to enable liver-specific delivery. In a high-fat diet-induced MASLD mouse model, Gc337 significantly improved insulin sensitivity, reduced hepatic lipid accumulation, and lowered body weight, with efficacy comparable to resmetirom, the only FDA-approved therapy for metabolic-associated steatohepatitis. A single injection sustained >50% hepatic Stk25 knockdown for 35 days without hepatotoxicity, underscoring its long-acting therapeutic profile. Importantly, c337 was designed to avoid all known single-nucleotide polymorphisms (SNPs), ensuring efficacy across genetically diverse populations. Together, these findings establish Gc337 as a durable, SNP-aware, and clinically translatable nucleic acid–based therapeutic candidate for MASLD. Overall design: In a high-fat diet-induced MASLD mouse model, mice were treated with either resmetirom or STK25 knockdown using Gc337. After the treatment period, liver tissues were collected for sequencing analysis.