Mirum Pharmaceuticals (MIRM) investor relations material

Disease background and unmet need

• Chronic hepatitis delta virus (HDV) is the most severe form of viral hepatitis, requiring hepatitis B coinfection for replication and spread.

• HDV leads to rapid progression to cirrhosis and liver failure, with over 50% liver-related death in 10 years and a threefold increased risk of liver cancer compared to HBV alone.

• Estimated prevalence is about 40,000 in the US, 230,000 in the US/EU, and over 12 million worldwide.

Study design and patient population

• AZURE-1 is a global Phase 2b/3 study enrolling about 200 patients with chronic HDV, randomized 2:2:1 to brelovitug 300 mg weekly, 900 mg every four weeks, or delayed treatment.

• The study included a broad patient population, including those with advanced liver disease, cirrhosis (41%), and portal hypertension (20%).

• No upper limit on ALT for participation; 18% had ALT >5x upper limit of normal.

• Brelovitug is a fully human anti-HBsAg monoclonal antibody administered subcutaneously weekly or monthly.

Efficacy results

• At week 24, 56% (300 mg weekly) and 45% (900 mg monthly) achieved the combined endpoint of virologic response plus ALT normalization, versus 0% in delayed treatment (p<0.0001).

• Virologic response rates were 86% (300 mg weekly) and 85% (900 mg monthly), with ALT normalization in 63% and 54% respectively at week 24.

• In the Phase 2b cohort, primary endpoint rates increased to 55% for both dosing arms at week 48, with deepening viral suppression and higher ALT normalization.

• No difference in response between cirrhotic and non-cirrhotic patients; all showed improvement over time.