Report on the AASLD/EASL Joint Workshop on Clinical Trial Endpoints in NAFLD.

Nonalcoholic fatty liver disease (NAFLD) is a global public health concern. Its natural history, the development of nonalcoholic steatohepatitis (NASH) and fibrosis, is highly variable, prone to endogenous (e.g., genetics, microbiota) and exogenous (e.g., nutrition, alcohol, physical activity) disease modifiers, and can fluctuate over time. The complexity of its pathophysiology is reflected by the multitude of pharmacological targets in development. NASH clinical trials have provided valuable insight that is applicable to future trial design. Endpoints for NASH have evolved over the past decade and will continue to be refined. Currently accepted endpoints for conditional approval include resolution of NASH without worsening of fibrosis and/or improvement in fibrosis without worsening of NASH by standardized evaluation of paired liver histology. In pediatric NASH, practical obstacles, pubertal hormonal changes, and stringent safety requirements mandate adaptations in trial design. In adult patients with NASH-related cirrhosis, clinical events (e.g. decompensation, hepatocellular carcinoma, transplantation, death) are more prevalent and thereby are viable primary endpoints. Consideration of the natural fluctuation of disease, the clinical implication of the chosen primary endpoint, and factors that may affect placebo response will facilitate an accurate determination of efficacy of emerging therapeutics for NASH. Conclusion: The June 2018 American Association for the Study of Liver Diseases and European Association for the Study of the Liver joint workshop on NAFLD endpoints summarized important findings from ongoing and completed trials, defined the scientific evidence supporting distinct endpoints, and provided guidance for future trial design.