Mirum Pharmaceuticals announced the completion of its acquisition of Bluejay Therapeutics, adding a late-stage liver disease program to its pipeline and positioning the company for potential entry into the treatment of chronic hepatitis delta virus (HDV), a rare and severe condition with no approved therapies in the United States.¹

HDV is a coinfection occurring in select people infected with the hepatitis B virus and is the most severe form of viral hepatitis due to its potential for rapid progression to liver cirrhosis, liver cancer, and liver-related death.¹ The disease affects an estimated 230,000 people in both the United States and Europe, with estimates suggesting that more than 50% of individuals with HDV will die of liver-related causes within 10 years of diagnosis.¹

The transaction brings Mirum the worldwide rights to brelovitug, a monoclonal antibody currently in Phase III development, reflecting Mirum’s strategy to expand within rare liver diseases through assets approaching potential registration.¹

Brelovitug is currently undergoing evaluations for the treatment of HDV, and with no approved treatments for HDV in the United States and most countries worldwide, it marks the indication as an area of significant unmet medical need.

“With the acquisition now complete, our focus shifts to execution –adding the talented Bluejay team to Mirum as we complete the AZURE Phase 3 program for HDV and prepare for potential registrations and launches,” said Chris Peetz, chief executive officer of Mirum.

What is brelovitug?

Brelovitug received both Breakthrough Therapy designation from FDA and PRIME designation from the European Medicines Agency, signifying regulatory recognition of its potential based on earlier clinical data.¹

Brelovitug is currently undergoing study in the global AZURE Phase III registrational program which is expecting topline data in the second half of 2026.¹ The AZURE program consists of multiple open-label studies designed to evaluate a combined virologic and biochemical response, with the primary goal of supporting regulatory submissions in the United States and Europe.

In Phase II studies, brelovitug demonstrated strong antiviral activity in HDV, including a complete HDV RNA response, improvements in liver enzyme levels, and a safety profile characterized primarily by injection-site erythema.¹ While Phase III data is expected to determine the drug’s ability to get approved, its existing dataset has continued to support its advancement into registrational studies.

A potential biologics license application submission and launch are expected in 2027 and are dependent on trial outcomes.¹

“This program fits squarely within our core strengths in rare disease and builds on our deep expertise in rare liver conditions. We believe Mirum’s global development and commercial synergies position us well to deliver for patients living with HDV,” Peetz said.

What are the financial details of the acquisition?

Per the terms of the acquisition agreement, Mirum is set to acquire all outstanding shares of Bluejay Therapeutics through a combination of cash and Mirum common stock, with the potential for additional tiered sales-based milestone payments.¹

In accordance with the acquisition, Mirum has also completed its previously announced private placement financings across both existing and new healthcare investors, generating upwards of $268.5 million in gross proceeds.¹ The capital is expected to help support ongoing clinical development and future commercial activities related to brelovitug.

Sources

1. Mirum Pharmaceuticals Completes Acquisition of Bluejay Therapeutics, Expanding Global Leadership in Rare Disease Mirum Pharmaceuticals January 26, 2026 https://www.businesswire.com/news/home/20260126610526/en/Mirum-Pharmaceuticals-Completes-Acquisition-of-Bluejay-Therapeutics-Expanding-Global-Leadership-in-Rare-Disease