Mirum Pharmaceuticals announced it has completed its acquisition of Bluejay Therapeutics, expanding Mirum’s footprint in rare liver disease with the addition of brelovitug, a late-stage monoclonal antibody being developed for chronic hepatitis delta virus.
The company said brelovitug carries FDA Breakthrough Therapy designation and European Medicines Agency PRIME and Orphan designations, and is currently being evaluated in the global AZURE Phase 3 registrational program, with topline data expected in the second half of 2026.
With the transaction closed, Mirum said it will focus on integrating Bluejay’s team and advancing the AZURE program toward potential regulatory filings and commercialization. Mirum indicated the Phase 3 effort is designed to support filings in the United States and Europe, and outlined a potential BLA submission and launch timeline in 2027, contingent on results and regulatory review.
Mirum described brelovitug as a highly potent, pan-genotypic, fully human IgG1 monoclonal antibody that targets the surface antigen on both HDV and HBV. The company said the investigational therapy is intended to neutralize and clear virions and reduce HBsAg-containing subviral particles. In Phase 2 studies, Mirum said brelovitug demonstrated strong antiviral activity in HDV, including a 100% HDV RNA response, improvements in liver enzyme levels, and a favorable safety profile, with injection-site erythema as the most common adverse event.
The company framed the HDV opportunity as a significant unmet need, describing the infection as the most severe form of viral hepatitis due to the risk of rapid progression to cirrhosis, liver cancer, and liver-related death. Mirum cited an estimate of approximately 230,000 people affected in the United States and Europe and said more than half of individuals with HDV may die of liver-related causes within 10 years of diagnosis. Mirum said there are currently no approved treatments for HDV in the United States and most countries worldwide.
Financially, Mirum said it acquired all outstanding shares of Bluejay for a combination of cash and Mirum common stock, with potential additional tiered sales-based milestone payments. Alongside the acquisition, Mirum said it closed previously announced private placement financings with existing and new healthcare investors, generating approximately $268.5 million in aggregate gross proceeds. The company said the proceeds are intended to support clinical development and commercial activities for brelovitug and added that it is evaluating strategic options for Bluejay’s additional investigational programs.
Mirum, which positions itself as a rare disease-focused company with a global commercial footprint, said its marketed portfolio includes LIVMARLI for Alagille syndrome and PFIC, CHOLBAM for bile-acid synthesis disorders, and CTEXLI for cerebrotendinous xanthomatosis. Beyond brelovitug, Mirum highlighted pipeline assets, including volixibat in late-stage development for PSC and PBC, and MRM-3379 being evaluated for Fragile X syndrome.
KEY QUOTES
“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.”
“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,” said Chris Peetz, Chief Executive Officer of Mirum Pharmaceuticals. “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.”
Chris Peetz, Chief Executive Officer of Mirum Pharmaceuticals
