On December 8, 2025 Mirum Pharmaceuticals, Inc. (Nasdaq: MIRM), a leading rare disease company, reported its entry into a definitive agreement to acquire Bluejay Therapeutics, a privately held biotechnology 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. This acquisition is expected to advance Mirum’s leadership in rare disease, build on its deep expertise in rare liver disorders and add a fourth potential registrational readout for the company over the next 18 months.

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Brelovitug is being evaluated in the AZURE Phase 3 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. In Phase 2 studies, brelovitug 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 3 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 through disciplined development, regulatory innovation, and commercial excellence," said Chris Peetz, Chief Executive Officer of Mirum Pharmaceuticals. "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. The Bluejay team has done commendable work advancing brelovitug to this stage and we look forward to building on that progress to bring this important new treatment to people living with HDV."

"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 3 trial in four years," said Keting Chu, Founder and CEO of Bluejay Therapeutics. "Brelovitug has the potential to redefine HDV treatment, and Mirum’s rare disease leadership, commitment to rare liver communities and commercialization expertise make it the right company to carry this program forward globally."

Under the terms of the definitive agreement, 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. The Mirum common stock issued to the Bluejay security holders at closing will be priced at $71.2085 per share. Mirum has also entered into a definitive agreement with a syndicate of existing and new healthcare investors, for the sale of Mirum common stock and, to certain investors, in lieu of Mirum common stock, pre-funded warrants, in a private placement. The private placement is expected to close concurrently with the acquisition and result in gross proceeds to Mirum of approximately $200 million before deducting placement agent and other offering expenses. The proceeds from the private placement are intended to fund clinical development and commercial activities following the proposed acquisition. The Mirum common stock issued to the private placement investors at closing will be priced at $68.48 per share (or $68.4799 per pre-funded underlying share of Mirum common stock, which equals the purchase price per share of Mirum common stock, less the $0.0001 per share exercise price of each pre-funded warrant). The transaction with Bluejay has been approved by the Boards of Directors of both companies and is expected to close in the first quarter of 2026, subject to regulatory approval and other customary closing conditions.

Beyond brelovitug for HDV, Mirum will evaluate strategic options for Bluejay’s additional investigational programs after close.

Morgan Stanley & Co. LLC acted as exclusive financial advisor to Mirum, and Cooley LLP served as legal counsel. Centerview Partners LLC acted as financial advisor to Bluejay, and Latham & Watkins LLP served as legal counsel. J.P. Morgan Securities LLC also provided financial advice to Bluejay. Mirum has engaged Morgan Stanley & Co. LLC, Leerink Partners LLC, Cantor Fitzgerald & Co., Raymond James & Associates, Inc. and Citizens JMP Securities, LLC as placement agents for the private placement.

Mirum to Host Conference Call

Mirum will host a conference call today, December 8, 2025 at 8:30 a.m. ET/5:30 a.m. PT, to provide further details on the transaction. Join the call using the following information:

United States/Toll-free: +1 833 470 1428
International: +1 646 844 6383
Access code: 490519
You may also access the call via webcast by visiting the Events & Presentations section on Mirum’s website. A replay of this webcast will be available for 30 days.

(Press release, Mirum Pharmaceuticals, DEC 8, 2025, View Source [SID1234661303])