Mirum Pharmaceuticals Provides AZURE Clinical Program Update for brelovitug in Chronic Hepatitis Delta Virus

Key Terms

phase 3 medical

Phase 3 is the late-stage clinical testing step for a new drug or medical treatment, where the product is given to large groups of patients to confirm effectiveness, monitor side effects, and compare it to standard care. Successful Phase 3 results are often the final scientific hurdle before regulators decide on approval and market launch—like passing a final exam before graduation—and can sharply change a company's valuation and future revenue prospects.

breakthrough therapy designation regulatory

A breakthrough therapy designation is a regulatory fast-track given to a drug or treatment that shows early signs of providing a major improvement over existing options for a serious condition. Think of it as a VIP lane that can speed up development and more intensive guidance from regulators, which matters to investors because it can shorten time to market, reduce development risk and potentially increase a company’s value — though it does not guarantee approval.

bla submission regulatory

A BLA submission is a company’s formal application to the U.S. Food and Drug Administration asking for permission to market a biologic drug or therapy. Think of it like applying for a permit to sell a complex medical product: the agency reviews safety, effectiveness, and manufacturing quality before deciding. For investors, a BLA filing signals a late-stage regulatory milestone that can reduce uncertainty and, if approved, unlock revenue and change a company’s valuation, while also carrying regulatory and timing risk.

virologic response medical

A virologic response is the measurable decline or disappearance of a virus in a patient after treatment, usually shown by lower levels of the virus in blood or tissues. For investors, it’s an early signal that an antiviral drug or vaccine is working—like seeing the smoke thin after firefighters start dousing a blaze—and strong, sustained responses can predict regulatory approval, broader use and commercial potential.

alt normalization medical

ALT normalization means a patient’s blood level of alanine aminotransferase (ALT), a key enzyme released by the liver when it’s stressed or damaged, has fallen back into the laboratory’s normal range. Investors watch this because drugs or treatments that cause persistent ALT elevations can signal liver toxicity and regulatory or market setbacks, while consistent ALT normalization is evidence of safety, like a stress indicator returning to green after a problem is fixed.

accelerated approval regulatory

Accelerated approval is a process that allows new medical treatments to be approved more quickly than usual if they address serious or life-threatening conditions and show promising early results. For investors, it signals that a treatment may reach the market sooner, potentially boosting a company's prospects, but it also involves some uncertainty since full evidence of effectiveness is still being gathered.

hepatitis delta virus medical

Hepatitis delta virus (HDV) is a small virus that can only infect people who also carry hepatitis B, acting like a hitchhiker that needs hepatitis B to enter liver cells and multiply. Because HDV typically causes faster, more severe liver damage and has few approved treatments, its presence affects demand for diagnostics, therapies and regulatory attention, making it a material clinical and commercial risk or opportunity for investors in related healthcare companies.

- Phase 3 AZURE-1 enrollment complete

- Phase 3 AZURE-4 screening complete

- Topline AZURE-1 and AZURE-4 results expected in 2H 2026

- AZURE-1 and AZURE-4 to form the basis of Mirum’s U.S. BLA Submission

FOSTER CITY, Calif.--(BUSINESS WIRE)-- Mirum Pharmaceuticals, Inc. (Nasdaq: MIRM), a leading rare disease company, today announced completion of enrollment in the Phase 3 AZURE-1 study and completion of screening in the Phase 3 AZURE-4 study, both evaluating brelovitug for the treatment of chronic hepatitis delta virus (HDV). Achievement of these milestones confirms the expected timing of topline 24-week data in the second half of 2026. AZURE-1 and AZURE-4 together will form the basis of Mirum’s U.S. BLA submission for brelovitug, which has received Breakthrough Therapy designation from the FDA for the treatment of chronic HDV infection.

Brelovitug is being developed for HDV, the most severe form of viral hepatitis, and a disease with no approved therapies in the U.S. HDV occurs in people already infected with hepatitis B virus (HBV) and is associated with rapid progression to liver fibrosis, cirrhosis, liver cancer, and liver-related death.

“The completion of AZURE-1 enrollment and AZURE-4 screening represent important execution milestones as we advance brelovitug through the Phase 3 AZURE program,” said Joanne Quan, M.D., Chief Medical Officer at Mirum Pharmaceuticals. “We look forward to reporting interim data from AZURE-1 in the second quarter and topline results from AZURE-1 and AZURE-4 in the second half of 2026. Both studies are evaluating a composite endpoint of virologic response and ALT normalization at 24 weeks, aligned with FDA guidance for accelerated approval in HDV, and building on the strong antiviral activity observed in our Phase 2 study.”

“HDV is an aggressive disease that progresses quickly and leaves patients with very limited treatment options,” said Tatyana Kushner, M.D., MSCE, Associate Professor of Medicine, Division of Gastroenterology and Hepatology at Weill Cornell Medicine. “Having a well-tolerated single-agent therapy that achieves viral suppression and improves liver inflammation is critical for patients with HDV, and the progress of these Phase 3 studies brings us closer to potentially delivering a new therapy to patients in urgent need.”

Topline data from AZURE-1 and AZURE-4 are expected in 2H 2026, with a potential BLA submission and launch in the U.S. in 2027.

About Brelovitug

Brelovitug is an investigational, highly potent, pan-genotypic, fully human immunoglobulin G1 (IgG1) monoclonal antibody (mAb) that targets the surface antigen (anti-HBsAg) on both the chronic hepatitis delta virus (HDV) and the hepatitis B virus (HBV). Brelovitug is designed to neutralize and remove hepatitis B and hepatitis D virions and deplete HBsAg-containing subviral particles. Brelovitug has FDA Breakthrough Therapy designation for the treatment of chronic HDV infection and PRIME and Orphan designations from the European Medicines Agency. In the Phase 2 study, brelovitug demonstrated strong antiviral activity in HDV, achieving a 100% HDV RNA response, along with improvements in liver enzyme levels and a favorable safety profile, with the most common adverse event being injection-site erythema. Mirum owns worldwide rights to brelovitug.

About the AZURE Clinical Program

The AZURE program is a global, registrational Phase 3 clinical development program evaluating brelovitug for the treatment of chronic hepatitis delta virus (HDV). The program includes multiple open-label studies designed to assess the primary endpoint of combined virologic and biochemical response. Together, the studies are intended to support regulatory filings in the United States and Europe.

About AZURE-1 and AZURE-4

AZURE-1 and AZURE-4 are Phase 3 studies that form the basis of Mirum’s U.S. FDA BLA submission for brelovitug in chronic hepatitis delta virus (HDV).

AZURE-1 is evaluating approximately 200 treatment-naïve patients randomized in a 2:2:1 ratio to receive brelovitug 300 mg once weekly, brelovitug 900 mg once monthly, or 24-week delayed therapeutic start. AZURE-4 is evaluating approximately 80 treatment-naïve patients randomized in a 2:1:1 ratio to receive brelovitug 300 mg once weekly, brelovitug 900 mg once monthly, or 12-week delayed therapeutic start. Patients randomized to delayed treatment initiate brelovitug 300 mg once weekly upon completion of the treatment delay in both studies. AZURE-4 is being conducted in partnership with PSI CRO.

The primary endpoint for both studies is the proportion of patients achieving combined virologic response and ALT normalization at Week 24, consistent with FDA guidance for accelerated approval in HDV. Both studies include open-label extension periods of up to 96 weeks.

About Mirum Pharmaceuticals

Mirum Pharmaceuticals (NASDAQ: MIRM) is a leading rare disease company with a global footprint of approved products and a broad pipeline of investigational medicines. Purpose-built to bring forward breakthrough medicines for people with overlooked conditions, Mirum combines deep rare disease expertise with strong connections to patient communities.

The company’s commercial portfolio includes LIVMARLI® (maralixibat) for Alagille syndrome (ALGS) and progressive familial intrahepatic cholestasis (PFIC), CHOLBAM® (cholic acid) for bile-acid synthesis disorders, and CTEXLI® (chenodiol) for cerebrotendinous xanthomatosis (CTX). Mirum’s clinical-stage pipeline includes volixibat, an IBAT inhibitor in late-stage development for primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC), brelovitug, a fully human monoclonal antibody in late-stage development for chronic hepatitis delta virus (HDV) and MRM-3379, a PDE4D inhibitor being evaluated for Fragile X syndrome (FXS).

Mirum’s success is driven by a team dedicated to advancing high impact medicines through strategic development, disciplined execution and purposeful collaboration across the rare disease ecosystem. Learn more at www.mirumpharma.com and follow Mirum on Facebook, LinkedIn, Instagram and X.

Forward-Looking Statements

Statements contained in this press release regarding matters that are not historical facts are “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Such forward-looking statements include statements regarding, among other things, expected timing of topline data for the AZURE studies or BLA submission, the quality of data to be submitted for a brelovitug BLA application in the US, the relationship of antiviral activity as an important endpoint in HDV and the success or approval of any potential regulatory submission for brelovitug. Because such statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. Words such as “anticipate,” “expected,” “will,” “could,” “would,” “potential,” “continue,” “plans,” “intended,” “believe,” and similar expressions are intended to identify forward-looking statements. These forward-looking statements are based upon Mirum’s current expectations and involve assumptions that may never materialize or may prove to be incorrect. Actual results could differ materially from those anticipated in such forward-looking statements as a result of various risks and uncertainties, which include, without limitation, risks associated with the development of acquired product candidates, including the failure of any expected synergies to be realized; risk and uncertainties arising from the integration of an acquired company, its employees and its assets with Mirum’s business; risks associated with evaluating companies and assets for acquisition, including that the perceived benefits of the acquisition are not realized; risks and uncertainties with the development of investigational medicines generally, including the failure of future studies to generate the same or similar data as prior studies and the potential that estimated prevalences are materially inaccurate; the risks and uncertainties associated with Mirum’s business in general, the impact of geopolitical and macroeconomic events, and the other risks described in Mirum’s Annual Report for the year ended December 31, 2024, filed with the Securities and Exchange Commission on February 26, 2025, and subsequent filings with the Securities and Exchange Commission, which are available at www.sec.gov. All forward-looking statements contained in this press release speak only as of the date on which they were made and are based on management’s assumptions and estimates as of such date. Mirum undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made, except as required by law.

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Investor Contact:
Andrew McKibben
ir@mirumpharma.com

Media Contact:
Meredith Kiernan
Media@mirumpharma.com

Source: Mirum Pharmaceuticals, Inc.