Mirum Pharmaceuticals said its experimental treatment brelovitug met the primary endpoint in a late-stage clinical trial for chronic hepatitis delta virus (HDV), with the drug reducing virus levels and improving liver health markers in patients with the disease.
Brelovitug is a monoclonal antibody designed to bind to the hepatitis B surface antigen, a protein found on the surface of the hepatitis B virus. The treatment is being developed for chronic HDV, a liver infection that occurs only in people who are already infected with hepatitis B. According to the company, the disease affects about 230,000 people across the United States and Europe and can lead to severe liver damage and death.
Phase 3 Trial Results
The phase 3 portion of the Azure-1 study randomized patients to receive either brelovitug or delayed treatment for 24 weeks. Participants received the therapy as subcutaneous injections of either 300 milligrams once weekly or 900 milligrams every four weeks.
At Week 24, both dosing regimens achieved the trial’s primary endpoint, which combined a virologic response with normalization of alanine aminotransferase (ALT), a marker of liver inflammation.
Mirum reported that 56% of patients receiving the 300-milligram dose and 45% of those receiving the 900-milligram dose met the combined endpoint, compared with 0% in the delayed-treatment control group.
The company also reported that approximately 85% of patients treated with brelovitug achieved a virologic response. ALT levels normalized in 63% of patients in the 300-milligram group and 54% of those receiving the 900-milligram regimen.
Mirum said treatment with brelovitug was well tolerated across dose groups and that the safety profile was consistent with previously reported findings.
Earlier Study Data and Long-Term Outcomes
The company also presented Week 48 data from the phase 2b portion of Azure-1, which included the first 53 patients enrolled in the study.
In the earlier analysis conducted at Week 24, 45% of patients in the 300-milligram group and 35% in the 900-milligram group achieved the primary endpoint. By Week 48, response rates had increased to 55% in both treatment groups.
The phase 2b data were presented alongside the phase 3 results and showed higher response rates at Week 48 than those reported at Week 24.
Focus on Liver Inflammation
Mirum selected a composite endpoint that assessed both viral reduction and liver inflammation.
“A virologic response alone does not necessarily mean that liver inflammation has resolved,” Nancy Shulman, M.D., executive vice president of clinical development at Mirum, said during a conference call with analysts.
Shulman said liver inflammation is a key driver of progression to fibrosis, cirrhosis, and liver cancer.
Regulatory Plans
Mirum said full results from the study will be presented at an upcoming medical congress. The company expects to submit a marketing application for brelovitug to the U.S. Food and Drug Administration in the first half of 2027.
The company is also expecting results from another phase 3 study, Azure-4, in the fourth quarter. Brelovitug became part of Mirum’s pipeline through its acquisition of Bluejay Therapeutics in a deal valued at $620 million that was completed late last year.
Mirum Pharmaceuticals announced that Brelovitug met the primary endpoint in the Phase 3 portion of the AZURE-1 study, evaluating the investigational treatment in adults with chronic hepatitis delta virus (HDV) infection. The results were announced on September 28, 2026.
Mirum Reports Positive AZURE-1 Results
The Phase 3 study enrolled 153 treatment-naive patients who were randomized to receive either Brelovitug 300 mg once weekly, Brelovitug 900 mg every four weeks, or delayed treatment. The primary endpoint measured a combined virologic response and normalization of alanine aminotransferase (ALT) levels at Week 24.
Mirum reported that 56% of patients receiving the 300 mg weekly dose achieved the combined endpoint, while 45% of patients receiving the 900 mg every-four-week dose reached it. No patients in the delayed-treatment group met the primary endpoint at Week 24. Both comparisons had a reported P value below 0.0001.
