Mirum Pharmaceuticals Expands Rare Liver Disease Portfolio with $820 Million Bluejay Therapeutics Acquisition

Brelovitug: A Late-Stage Asset with Breakthrough Potential

Brelovitug is a highly potent, pan-genotypic, fully human monoclonal antibody that targets hepatitis B surface antigen (HBsAg), designed to treat chronic HDV and HBV infections. It holds both FDA Breakthrough Therapy and EMA PRIME designations, underscoring its potential to address a significant unmet medical need in rare liver diseases. The drug is currently in the global Phase 3 AZURE program, with key interim and top-line data anticipated between 2026 and 2028. Mirum estimates the worldwide annual revenue opportunity for brelovitug in HDV alone to exceed $750 million.

Strategic Rationale and Pipeline Synergies

This acquisition complements Mirum’s existing portfolio of rare liver disease programs, including therapies for cholestatic liver diseases and other rare hepatic conditions. By integrating brelovitug, Mirum adds a fourth potential registrational readout within the next 18 months, accelerating its clinical and commercial momentum. The deal leverages Mirum’s deep expertise in rare liver disorders and positions the company to capture a larger share of the rare disease market, which is witnessing increased investor interest and regulatory support.

Leadership and Industry Impact

Bluejay Therapeutics was founded by Dr. Keting Chu, a seasoned biotech executive with a strong track record in therapeutic development and venture investing. Dr. Chu’s leadership in advancing antibody therapeutics and her experience with successful biotech IPOs and acquisitions add significant value to Mirum’s expanded rare disease platform.

Market and Investor Response

Following the announcement, Mirum’s shares experienced a modest decline of up to 5%, reflecting typical market reactions to sizable acquisitions. However, Wall Street analysts, including Cantor Fitzgerald, have expressed bullish outlooks, raising price targets and highlighting the deal as a strategic “steal” given brelovitug’s late-stage status and commercial potential. Retail investor sentiment on platforms like Stocktwits shifted positively, indicating growing confidence in Mirum’s growth trajectory.

Broader Context: Rare Liver Disease M&A Trends in 2025

The Mirum-Bluejay deal exemplifies a broader trend in 2025 where biopharma companies are aggressively pursuing late-stage assets in rare and orphan liver diseases, driven by favorable regulatory pathways such as Breakthrough Therapy and PRIME designations. Private equity and strategic investors are increasingly backing such acquisitions, recognizing the high unmet medical need and attractive market dynamics. The transaction also underscores the growing importance of monoclonal antibody therapeutics in viral hepatitis treatment paradigms.

Key Takeaways for C-Level Executives and Deal Advisors

• Strategic Fit: Acquiring late-stage assets with regulatory designations accelerates time-to-market and de-risks pipeline development.
• Financial Engineering: Combining upfront cash, stock consideration, milestone payments, and private placements optimizes capital structure and investor alignment.
• Leadership Depth: Integration of experienced biotech entrepreneurs enhances innovation and execution capabilities post-acquisition.
• Market Positioning: Expanding rare liver disease portfolios positions companies to capitalize on growing rare disease market valuations and regulatory incentives.

Visual Summary: Mirum Pharmaceuticals Acquisition of Bluejay Therapeutics

Mirum’s acquisition of Bluejay Therapeutics marks a pivotal expansion into viral hepatitis and rare liver diseases, reinforcing its position as a leader in rare disease drug development. This transaction highlights the strategic value of late-stage, regulatory-designated assets and the importance of innovative financing structures in contemporary biotech M&A.