Mirum Pharmaceuticals signed a definitive agreement to acquire Bluejay Therapeutics, a privately-held biotech company focused on viral and liver diseases. The transaction would add worldwide rights to brelovitug, a late-stage, fully human monoclonal antibody with Breakthrough Therapy and PRIME designations for chronic hepatitis delta virus (HDV) to Mirum’s portfolio of rare liver programs, according to Mirum officials.
Brelovitug is being evaluated in the AZURE Phase III registrational program for HDV, the most severe form of viral hepatitis. HDV occurs in people already infected with hepatitis B; nearly half of those affected progress to liver-related death within 10 years of diagnosis due to rapid progression to fibrosis, cirrhosis, hepatic decompensation, and an increased risk of liver cancer.
Strong antiviral activity
In Phase II studies, brelovitug reportedly demonstrated strong antiviral activity in HDV, achieving 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. The ongoing global AZURE Phase III program is currently enrolling patients, with top-line data expected in 2H 2026 and potential BLA submission and launch in 2027.
“This acquisition fits squarely with what we do best—advancing high-impact medicines for patients with rare diseases,” said Chris Peetz, CEO of Mirum Pharmaceuticals. “Brelovitug in HDV leverages our expertise in rare liver disease and builds on the relationships we’ve established with providers through the volixibat and LIVMARLI programs.”
“Bluejay was founded to develop transformative therapies for people with viral and liver diseases and, working with regulatory agencies, such as the FDA and the European Medicines Agency, the Bluejay team developed brelovitug from clinical development candidate to global Phase III trial in four years,” noted Keting Chu, founder and CEO of Bluejay Therapeutics.
Mirum has agreed to acquire all outstanding shares of Bluejay for $250 million in cash and $370 million in Mirum common stock, plus potential tiered sales-based milestone payments of up to $200 million in cash.
