S5889 Real-World Fibrosis and Steatosis Rapid Reversal With Resmetirom in Dual-Etiology Liver Disease (MASH and Chronic Hepatitis B)

Introduction: Metabolic dysfunction-associated steatohepatitis (MASH), previously known as Non-alcoholic steatohepatitis (NASH), is a progressive fatty liver disease commonly associated with metabolic co-morbidities, which in turn increase the risk of hepatic fibrosis. Previous research showed that the recently FDA-approved thyroid hormone receptor-β agonist Resmetirom has been effective in lowering hepatic steatosis and fibrosis. Still, there is a lack of available data for cases with dual hepatic disease. We present a case illustrating the potential efficacy of resmetirom in a patient with MASH and concurrent chronic hepatitis B. Case Description/Methods: A 55-year-old man with a medical history of obesity, DM II, hyperlipidemia, chronic hepatitis B (HBV) infection since 2020 (treatment naive), GERD, and H. pylori infection, who was undergoing routine surveillance for MASH without cirrhosis. On follow-up in September 2024, he was found to have advanced fibrosis (F3) and moderate to severe steatosis (S2–S3) using the FibroScan technique. At that point, his HBV DNA level was 566 IU/mL, and his alanine aminotransferase level was 38 U/L. He began treatment with Resmetirom at 80 mg/day, and 5 months later, significant clinical and histological improvements were observed, including complete resolution of steatosis (S0) and regression of fibrosis to stage F0 on FibroScan in February 2025. LFTs and metabolic indicators remained within range, with no HBV reactivation or complication during treatment. Discussion: Our case reveals the potential use of Resmetirom in attaining rapid histological reversal in patients with MASH and chronic HBV co-infection. The regression from advanced fibrosis (F3) to no fibrosis (F0) and complete reversal of steatosis within 5 months is significant, specifically in a patient who did not receive concurrent antiviral therapy. This reveals that resmetirom has a wider impact on reversing liver inflammation and fibrogenesis, even in cases with dual chronic liver diseases. Given the immunometabolic changes brought on by medication, the lack of HBV reactivation during treatment is also favorable, but it shouldn't preclude careful virologic monitoring in cases like this, and it highlights the need for further research into the efficacy and safety of resmetirom in patients with dual hepatic conditions, a population that is often excluded from clinical trials.