Mirum Advances Brelovitug in Phase 3 Hepatitis Delta Trial

Foster City, California, U.S., September 28, 2026

Brelovitug Meets Phase 3 Primary Endpoint

The Phase 3 AZURE-1 study enrolled 153 treatment-naive patients with chronic HDV and randomized participants to receive either brelovitug 300 mg once weekly, brelovitug 900 mg once every four weeks, or delayed treatment beginning after Week 24. The study’s primary endpoint combined virologic response and alanine aminotransferase (ALT) normalization, providing measures of both viral suppression and biochemical improvement. At Week 24, 56% of patients receiving 300 mg weekly and 45% receiving 900 mg every four weeks achieved the combined endpoint, compared with 0% in the delayed-treatment group. Both comparisons against delayed treatment reached statistical significance, with p-values below 0.0001. Additional virologic results showed that 86% of patients in the 300 mg weekly group and 85% in the 900 mg every-four-week group achieved the study’s defined virologic response. HDV RNA became below the lower limit of quantification in 25% and 26% of patients, respectively, while 17% in each treatment group had HDV RNA levels classified as target not detected. ALT normalization occurred in 63% of patients receiving weekly treatment and 54% receiving the every-four-week regimen. These findings provide multiple measures of antiviral and biochemical activity, although full study results are expected to be presented at a future medical congress.

Investigational Antibody Targets Hepatitis Delta

Brelovitug is a fully human monoclonal antibody designed to bind hepatitis B surface antigen (HBsAg). Because HDV relies on hepatitis B virus components during its lifecycle, targeting HBsAg represents an approach intended to interfere with the viral disease process. Mirum is developing brelovitug as a potential treatment for chronic HDV, the most severe form of viral hepatitis. The candidate is being evaluated as part of the company’s broader rare-liver-disease pipeline. Earlier Phase 2b findings from AZURE-1 had already shown antiviral activity. At Week 24, the primary composite endpoint was achieved by 45% of patients in the 300 mg weekly group and 35% in the 900 mg every-four-week group, compared with 0% in the delayed-treatment group. Mirum subsequently reported that the Phase 2b portion showed further viral suppression and increasing rates of ALT normalization through 48 weeks, providing additional longer-term data as the program progressed into Phase 3.

Safety Supports Continued Late-Stage Development

Mirum reported that brelovitug was well tolerated across the Phase 3 dose groups, with no new safety signals identified through Week 24. In the 300 mg weekly group, 45.8% of participants experienced an adverse event, compared with 61.5% in the 900 mg every-four-week group and 27.6% in the delayed-treatment group. Injection-site reactions and flu-like symptoms were among the reported events, while no patients receiving brelovitug discontinued treatment because of an adverse event.

The AZURE-1 findings are part of a broader registrational development program. AZURE-1 and AZURE-4 are intended to form the basis of Mirum’s planned U.S. Biologics License Application for brelovitug. The company expects topline results from AZURE-4 in the fourth quarter of 2026 and has stated that it plans to submit a BLA to the U.S. FDA in the first half of 2027. Brelovitug has previously received FDA Breakthrough Therapy designation for chronic HDV. The candidate remains investigational and is not yet FDA-approved.

Source: Mirum Pharmaceuticals press release