Mirum Reports Positive Late-Stage Data for Hep D

Rare Daily Staff

Mirum Pharmaceuticals said its experimental therapy brelovitug met the main goal of a phase 3 study in hepatitis delta, a rare but often deadly liver infection, and that the company will seek regulatory approval to market the drug next year.

In the AZURE-4 study, 59 percent of patients who injected themselves with the drug once a week had both a sharp drop in the virus and normal levels of a key marker of liver damage after 24 weeks. None of the patients whose treatment was delayed reached that goal.

AZURE-4 is the second of two phase 3 studies Mirum plans to use to support its application. The first, AZURE-1, reached its main goal in September. The company plans to file with the Food and Drug Administration in the first half of 2027 and, if the drug is approved, could launch it in the U.S. in late 2027.

Hepatitis delta virus, or HDV, can’t survive on its own. It infects only people who also have hepatitis B, and it uses a hepatitis B protein as its outer coat. The combination is especially dangerous. HDV is considered the most severe form of viral hepatitis because it can quickly lead to cirrhosis (scarring of the liver), liver cancer and death.

Brelovitug is a fully human immunoglobulin G1 monoclonal antibody that targets the surface antigen on both the hepatitis delta virus and the hepatitis B virus. It is designed to neutralize and remove hepatitis B and hepatitis D virions and to deplete HBsAg-containing subviral particles. The drug has FDA Breakthrough Therapy designation for the treatment of chronic HDV and Orphan Drug designation for the treatment of active HDV infection. It also has PRIME and orphan designations from the European Medicines Agency.

AZURE-4 enrolled 113 people who had never been treated for HDV. Many were very sick: More than half already had cirrhosis, about half had very high levels of the virus in their blood, and on average their levels of ALT, a liver enzyme that rises when the liver is inflamed or damaged, were well above normal.

To count as a success, a patient needed both a large drop in the virus and a return to normal ALT levels. That goal was met by 59 percent of patients on the weekly dose and 44 percent of those on the monthly dose. Measured separately, about 95 percent of patients in both dose groups had a large drop in the virus.

The drug was generally well tolerated. The most common side effect was a flu-like illness, reported in about 17 percent to 19 percent of patients, mostly after the first dose. Few patients had reactions at the injection site.

Mirum already markets several medicines for rare liver and genetic diseases, including Livmarli for the childhood liver disorders Alagille syndrome and progressive familial intrahepatic cholestasis.