Mirum Pharmaceuticals, Inc., a leading rare disease company, has entered a definitive agreement to acquire Bluejay Therapeutics, a privately held biotechnology firm focused on viral and liver diseases. The acquisition will add global rights to brelovitug, a late-stage, fully human monoclonal antibody with Breakthrough Therapy and PRIME designations for chronic hepatitis delta virus (HDV), further strengthening Mirum’s rare liver disease portfolio. With this addition, Mirum expects to gain a fourth potential registrational readout within the next 18 months.

Brelovitug is currently being evaluated in the global AZURE phase 3 registrational programme for HDV, the most severe form of viral hepatitis. HDV occurs only in individuals already infected with hepatitis B and is associated with rapid progression to fibrosis, cirrhosis, liver cancer, and liver-related death. Nearly half of affected patients die within 10 years of diagnosis. In phase 2 trials, brelovitug demonstrated strong antiviral activity, achieving a 100 percent HDV RNA response, along with improved liver enzyme levels and a favourable safety profile. Top-line data from the AZURE phase 3 programme are expected in the second half of 2026, with a potential BLA submission and commercial launch in 2027.

Chris Peetz, chief executive officer of Mirum Pharmaceuticals, said the acquisition aligns perfectly with the company’s strategy of advancing impactful therapies for rare diseases through disciplined development and regulatory innovation. He noted that brelovitug builds on Mirum’s expertise in rare liver disorders established through its volixibat and LIVMARLI programmes.

Keting Chu, founder and chief executive officer of Bluejay Therapeutics, highlighted that brelovitug progressed from candidate selection to a global phase 3 programme in only four years. She said Mirum’s leadership in rare diseases and its strong commercial capabilities make it well positioned to advance brelovitug worldwide.

Under the terms of the agreement, Mirum will acquire all outstanding shares of Bluejay for 250 million USD in cash and 370 million USD in Mirum common stock, with additional tiered sales-based milestone payments of up to 200 million USD. The Mirum shares issued to Bluejay investors will be priced at 71.2085 USD per share. Mirum has also secured a separate private placement with existing and new healthcare investors, expected to generate approximately 200 million USD in gross proceeds to support development and commercialisation activities. These shares will be priced at 68.48 USD per share (or 68.4799 USD per pre-funded warrant). The acquisition is expected to close in the first quarter of 2026, subject to regulatory and customary approvals.

Following closing, Mirum will own worldwide rights to brelovitug and will evaluate additional Bluejay pipeline assets.

Mirum Pharmaceuticals is a global rare disease company with approved products and a broad pipeline targeting overlooked conditions. Bluejay Therapeutics is a clinical-stage biopharmaceutical company focused on transformative therapies for serious viral and liver diseases.