Mirum Pharmaceuticals has announced that brelovitug met the primary endpoint in the Phase 3 portion of the AZURE-1 study evaluating the investigational antibody in patients with chronic Hepatitis Delta Virus (HDV).

At Week 24, 56 percent of patients receiving brelovitug 300 mg once weekly and 45 percent receiving 900 mg once every four weeks achieved the combined endpoint of virologic response and Alanine Aminotransferase (ALT) normalization. This compared with 0 percent in the delayed-treatment group, with both comparisons reaching statistical significance.

The Phase 3 portion of AZURE-1 enrolled 153 treatment-naive patients, including those with advanced liver disease. Brelovitug was administered by subcutaneous injection either weekly or every four weeks.

The company also reported 48-week data from the Phase 2b portion of the study, showing further viral suppression, with more patients achieving HDV RNA below the lower limit of quantification or target not detected. Rates of ALT normalization also increased through Week 48.

Brelovitug was well tolerated across the treatment groups, with no new safety signals reported through 48 weeks in the Phase 2b portion. The full Phase 3 AZURE-1 results will be presented at an upcoming medical congress.

AZURE-1 is one of two pivotal Phase 3 studies intended to support Mirum's US registration package for brelovitug. Topline results from the second study, AZURE-4, are expected in the fourth quarter of 2026. Mirum plans to submit a Biologics License Application to the US Food and Drug Administration in the first half of 2027.

Brelovitug is an investigational fully human IgG1 monoclonal antibody designed to target hepatitis B surface antigen (HBsAg) associated with hepatitis B and hepatitis D viruses. It is being developed for chronic HDV, a viral infection associated with an increased risk of liver cirrhosis, liver cancer and liver-related complications.

Brelovitug has received Breakthrough Therapy designation from the US FDA and PRIME and Orphan designations from the European Medicines Agency. Mirum holds worldwide rights to the programme.