Mirum Pharmaceuticals (NASDAQ: MIRM) has announced a definitive agreement to acquire privately held Bluejay Therapeutics in a transformative deal that expands Mirum’s leadership in rare liver diseases and adds a high-potential late-stage asset to its growing pipeline. The acquisition, valued at $620 million upfront in cash and stock — plus up to $200 million in milestone payments — brings worldwide rights to brelovitug, a fully human monoclonal antibody currently in Phase 3 development for chronic hepatitis delta virus (HDV).
For Mirum, a company already recognized for developing and commercializing rare disease therapies—including LIVMARLI, CHOLBAM and CTEXLI—the deal aligns directly with its strategic focus: advancing life-changing medicines for overlooked patient populations. HDV, the most severe form of viral hepatitis, represents a large, high unmet-need market with no FDA-approved treatments, affecting more than 230,000 people across the U.S. and Europe.
Brelovitug has already gained international attention. The therapy holds FDA Breakthrough Therapy designation and the European Medicines Agency’s PRIME and Orphan designations. In Phase 2 trials, it demonstrated strong antiviral activity and a 100% HDV RNA response rate, along with improvements in liver enzyme levels. Its safety profile has been favorable, with the most notable adverse event being injection-site reactions.
The drug is currently being evaluated in the global, registrational AZURE Phase 3 program, which is enrolling patients worldwide. Top-line results are expected in the second half of 2026, with a potential BLA submission and commercial launch in 2027. If approved, brelovitug could become the first widely available treatment for chronic HDV.
Mirum CEO Chris Peetz emphasized that the acquisition fits squarely within Mirum’s mission and capabilities. “Brelovitug in HDV leverages our deep expertise in rare liver disease and builds on the relationships we’ve established with key providers through the volixibat and LIVMARLI programs,” he said. Bluejay’s founder and CEO, Keting Chu, echoed that sentiment, noting that Mirum’s rare disease specialization makes it “the right company to carry this program forward globally.”
The acquisition will be funded through a combination of cash, Mirum common stock, and a concurrent $200 million private placement with healthcare investors. Proceeds from the placement will support both clinical development and future commercial activities. The deal not only adds a late-stage asset to Mirum’s portfolio but also positions the company for four potential registrational readouts within the next 18 months—an unusually rich pipeline for a rare-disease-focused biotech.
Implications for the Biotech Landscape
The acquisition underscores a broader trend in the biotechnology sector: rare disease companies with commercial infrastructure are increasingly seeking late-stage assets to accelerate revenue growth and expand global presence. For small and mid-cap biopharma firms, especially those with single or early-stage assets, partnerships or acquisitions by specialized players like Mirum remain attractive pathways to scale.
Bluejay itself represents a textbook example of a high-quality private biotech that rapidly advanced a novel therapy—from development candidate to global Phase 3 program in four years—making it an appealing target in a competitive rare-disease market.
Pending regulatory approvals, the transaction is expected to close in the first quarter of 2026. If successful, brelovitug could mark one of the most important therapeutic advancements in liver disease in decades—and a major milestone in Mirum’s evolution into a global leader in rare hepatology.