Background: Fat toxicity results in inflammation of the liver and eventual hepatic fibrosis and cirrhosis. Thyroid hormones can greatly reduce this hepatic steatosis by restoring metabolic pathways in damaged liver, prevent fibrosis progression, and have broad atherogenic lipid-lowering actions by activating hepatic thyroid beta-receptors.
However, hyperthyroidism also leads to osteoporosis, tachyarrhythmias, muscle wasting, and psychiatric side effects, mediated by the alpha-thyroid receptor. Resmetirom (MGL-3196) is a novel, highly selective thyroid beta-agonist, with a minimal side-effect profile, which avoids the alpha–side effects.
Study design: Randomized, double-blind, placebo-controlled study.
Setting: 25 centers in the United States.
Synopsis: Of 125 adults with NASH fibrosis 1-3 and greater than 10% hepatic fat, 84 received resmetirom and 41 received placebo. Resmetirom resulted in a nearly 30% decrease over placebo in hepatic fat, compared with baseline, significant improvement in lipid profile, improvement in liver enzymes, fibrosis markers, and histologic resolution of NASH in some patients.
While the study showed resolution of inflammation, the 36-week study was likely not long enough to show improvement of fibrosis. The relatively small sample size also limited results. Placebo patients who lost significant weight also showed improvement and were discarded from analysis, suggesting that weight loss itself is also an excellent alternative to reverse NASH. Resmetirom use in NASH is now moving into a large phase 3 trial.
Bottom line: Resmetirom results in major liver and cardiovascular benefits in patients with NASH.
Citation: Harrison SA et al. Resmetirom (MGL-3196) for the treatment of nonalcoholic steatohepatitis: A multicentre, randomised, double-blind, placebo-controlled, phase 2 trial. Lancet. 2019 Nov 11;394(10213):2012-24.
Dr. Raghavan is assistant professor in the division of hospital medicine, Loyola University Medical Center, Maywood, Ill.