A Precision Medicine Approach Using Gene Silencing to Treat a Chronic Liver Disease Called Non-Alcoholic Steatohepatitis (NASH) in Adult Participants at Increased Genetic Risk for This Condition

This study is researching an investigational drug called ALN-HSD (called "study drug"). This study is focused on participants who are known to have non-alcoholic steatohepatitis (NASH). NASH is a form of non-alcoholic fatty liver disease (NAFLD). Recently, the name metabolic dysfunction associated steatohepatitis (MASH) has been introduced to replace NASH and metabolic dysfunction-associated steatotic liver disease (MASLD) to replace NAFLD. NASH occurs when fat builds up in liver cells, damaging them, and making the liver inflamed and stiff from fibrosis (scar tissue). NASH can progress to cirrhosis (long term scarring) and liver failure (when the liver cannot perform its job). The aim of the study is to see the effect of the study drug on lessening liver scarring side effects related to NASH.

The study is looking at several other research questions, including:

• How the study drug works to improve liver function and lessen NASH related inflammation in the liver

• What side effects may happen from receiving the study drug

• How much study drug and study drug metabolites (byproduct of the body breaking down the study drug) are in the blood at different times

• Better understanding of the study drug and NASH