Mirum Acquires Bluejay, Adding Brelovitug Treatment for HDV

The finalization of the acquisition of Bluejay Therapeutics by Mirum Pharmaceuticals represents a significant shift in the late-stage development landscape for rare and severe viral liver conditions. This transaction centers on the addition of brelovitug, a monoclonal antibody currently being evaluated for chronic hepatitis delta virus (HDV), a disease that currently lacks any approved therapies from the FDA in the United States.¹ The integration of the Bluejay team into Mirum is intended to facilitate the completion of registrational programs and the transition toward potential commercial manufacturing.

How does this acquisition impact the late-stage development landscape for chronic viral hepatitis?

Brelovitug is characterized as a highly potent, pan-genotypic, fully human immunoglobulin G1 monoclonal antibody.¹ Its mechanism of action involves targeting the surface antigen on both the chronic hepatitis delta virus and the hepatitis B virus (HBV) to neutralize and remove virions while depleting subviral particles. This approach is technically significant because HDV is considered the most severe form of viral hepatitis, often progressing rapidly to cirrhosis and liver cancer¹. An estimated 230,000 people in the United States and Europe live with the condition, and more than 50% of those diagnosed will die from liver-related causes within 10 years, according to Mirum.¹

The asset is currently moving through the AZURE program, a global Phase 3 registrational development effort consisting of multiple open-label studies. These studies focus on a primary endpoint of combined virologic and biochemical response, with topline data anticipated in the second half of 2026. Discussing the strategic shift following the merger, Chris Peetz, CEO of Mirum, stated in a press release, “With the acquisition now complete, our focus shifts to execution – adding the talented Bluejay team to Mirum as we complete the AZURE Phase 3 program for HDV and prepare for potential registrations and launches”.¹

The successful execution of these Phase 3 trials is a prerequisite for a potential Biologics License Application (BLA) submission and a subsequent launch in 2027. The development team's ability to maintain the strong antiviral activity observed in Phase 2 studies, which reported a 100% HDV ribonucleic acid response and a favorable safety profile,¹ will be a critical factor in regulatory success.

What are the technical and regulatory implications for future commercialization?

The regulatory pathway for brelovitug is supported by its Breakthrough Therapy designation from the FDA and its PRIME and Orphan designations from the European Medicines Agency.¹ To support the clinical and commercial activities required to bring this biologic to market, Mirum successfully completed private placement financings resulting in approximately $268.5 million in gross proceeds.¹

Chris Peetz, Chief Executive Officer of Mirum Pharmaceuticals, emphasized the operational transition in a press release, “With the acquisition now complete, our focus shifts to execution – adding the talented Bluejay team to Mirum as we complete the AZURE Phase 3 program and prepare for potential registrations and launches.” He further elaborated on the synergy between the two organizations in a press release, “This program fits squarely within our core strengths in rare disease and builds on our deep expertise in rare liver conditions. We believe Mirum’s global development and commercial synergies position us well to deliver for patients living with HDV.”¹

As the company evaluates strategic options for additional investigational programs acquired from Bluejay, it will leverage its existing commercial infrastructure.¹ Mirum already manages a portfolio of approved products for rare conditions, including Alagille syndrome, progressive familial intrahepatic cholestasis, and bile-acid synthesis disorders.² This established expertise in navigating the rare disease ecosystem and managing complex biologic pipelines is expected to be instrumental as the company prepares for a potential BLA and the global delivery of brelovitug.

References:

1. Business Wire. Mirum Pharmaceuticals Completes Acquisition of Bluejay Therapeutics, Expanding Global Leadership in Rare Disease. Press Release. Jan 26, 2026.
2. Mirum. Mirum’s Volixibat Achieves Positive Interim Analyses in VANTAGE PBC and VISTAS PSC Studies. Press Release. Jan 17, 2026.