Defining Improvement in Nonalcoholic Steatohepatitis for Treatment Trial Endpoints: Recommendations From the Liver Forum

Identifying effective therapies for nonalcoholic steatohepatitis (NASH) with fibrosis is a pressing challenge, with 1%-2% of the population in developed nations at risk of developing NASH cirrhosis and its complications. The design of NASH clinical therapeutic trials is hampered by the long period of minimally symptomatic disease that typically precedes the development of decompensated cirrhosis and the accompanying uncertainties regarding the best precirrhotic trial endpoints that reliably reflect a subsequent reduction in liver-related morbidity and mortality. The Liver Forum is a multistakeholder organization comprised of academic, industry, and regulatory experts working from a regulatory science perspective to identify barriers, prioritize research, and identify solutions to accelerate therapeutic development for NASH. Past work of The Liver Forum has focused on recommendations for disease definitions and baseline parameters to be implemented in clinical trials that are designed to assess disease status and prevent progression to cirrhosis, liver transplantation, hepatocellular carcinoma, and death. The purpose of this summary is to review currently available clinical data to identify parameters that change in parallel with liver histology and are likely to reflect clinically meaningful reductions in the risk of developing cirrhosis and its complications. We review available data on exploratory histological, blood-based, and imaging pharmacodynamic biomarkers that may reflect meaningful treatment responses and provide recommendations regarding measurements to be considered in phase 2 and 3 trials as well as during postmarketing monitoring trials.