FOSTER CITY, Calif. — Mirum Pharmaceuticals announced it has entered into a definitive agreement to acquire Bluejay Therapeutics, a privately held biotechnology company developing treatments for viral and liver diseases. The deal adds brelovitug — a late-stage monoclonal antibody with Breakthrough Therapy and PRIME designations for chronic hepatitis delta virus — to Mirum’s growing rare liver disease pipeline. The company said the acquisition strengthens its position in rare disease and is expected to provide a fourth potential registrational readout within the next 18 months.
Brelovitug is currently being studied in the AZURE Phase 3 program for chronic hepatitis delta virus, the most severe form of viral hepatitis. The condition affects people already infected with hepatitis B and often progresses rapidly to fibrosis, cirrhosis, hepatic decompensation and elevated liver cancer risk. Nearly half of those diagnosed die from liver-related causes within a decade. In Phase 2 studies, brelovitug produced strong antiviral activity, achieving a 100 percent HDV RNA response and demonstrating favorable liver enzyme improvements and a generally well-tolerated safety profile. The ongoing global Phase 3 trial is enrolling patients, with top-line results expected in the second half of 2026 and a potential U.S. filing 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 relationships we’ve established through the volixibat and LIVMARLI programs. The Bluejay team has done commendable work advancing brelovitug to this stage, and we look forward to bringing this important therapy to people living with HDV.”
Keting Chu, founder and CEO of Bluejay Therapeutics, said Mirum is well positioned to advance the program globally. “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,” she said.
Under the agreement, Mirum will acquire all outstanding shares of Bluejay for $250 million in cash and $370 million in Mirum common stock, with potential sales-based milestone payments of up to $200 million. Mirum also entered into a separate agreement with a syndicate of healthcare investors for a private placement of common stock and pre-funded warrants, expected to close concurrently with the acquisition and generate approximately $200 million in gross proceeds. The funds will support clinical development and commercial activities after the deal closes.
The transaction has been approved by the boards of both companies and is expected to close in the first quarter of 2026, subject to regulatory approvals and customary conditions. Mirum said it will evaluate options for Bluejay’s additional investigational programs once the acquisition is complete.
