Mirum Pharmaceuticals has entered a definitive agreement to acquire Bluejay Therapeutics — a deal that, if finalized, would add brelovitug, a phase 3-stage monoclonal antibody for chronic hepatitis delta virus, to its rare liver disease therapy pipeline.
The $620 million deal includes $250 million in cash and $370 million in Mirum common stock, with up to $200 million in potential sales-based milestone payments, according to a Dec. 8 news release. Brelovitug holds a breakthrough therapy designation from the FDA.
The fully human monoclonal antibody is being evaluated in a global AZURE phase 3 program, with topline data expected in the second half of 2026. In phase 2, brelovitug achieved a 100% HDV RNA response and showed improvements in liver enzyme levels.
The acquisition is expected to close in the first quarter of 2026, pending “regulatory approval and other customary closing conditions,” according to the release.
