RiverVest Funds I, II & III RiverVest Fund IV Archer Seed Fund

DECEMBER 2025

Portfolio Company Bluejay Therapeutics to be Acquired by Mirum Pharmaceuticals

ST. LOUIS–(December 8, 2025)— Bluejay Therapeutics – a RiverVest Venture Fund V portfolio company – has entered into a definitive agreement to be acquired by Mirum Pharmaceuticals, Inc. (Nasdaq: MIRM), a former RiverVest portfolio company focusing on rare liver diseases.

 

The transaction would add Bluejay’s brelovitug, a late-stage, fully human monoclonal antibody with Breakthrough Therapy, Orphan, and PRIME designations for chronic hepatitis delta virus (HDV), to Mirum’s portfolio of rare liver programs.

 

Read the Joint Press Release

RiverVest co-led Bluejay’s $20 million Series A financing in 2021 and participated in the $41 million Series B round in 2022 and the $182 million Series C round in 2024. In addition to its financial commitment, RiverVest provided hands-on guidance with Principal Pascal Krotee, Ph.D., serving on Bluejay’s board of directors and Managing Director Niall O’Donnell, Ph.D., serving as an observer to the board.

 

“RiverVest is proud of our early and active role in Bluejay’s success, providing scientific, operational, and financial guidance to support the rapid advancement of brelovitug through clinical trials,” said Dr. Krotee. “This acquisition exemplifies RiverVest’s commitment to doing business the right way to deliver the best outcomes for patients, entrepreneurs, and investors.”

 

“Bluejay’s acquisition exemplifies RiverVest’s commitment to doing business the right way to deliver the best outcomes for patients, entrepreneurs, and investors.”

PASCAL KROTEE, PHD

Principal

RiverVest Venture Partners

Brelovitug (BJT-778) is a high potency, fully human immunoglobulin G1 (IgG1) monoclonal antibody (mAb) that targets the surface antigen (anti-HBsAg) of the hepatitis B virus with pan-genotypic activity. It is being investigated as a potential monotherapy for adults with chronic hepatitis D and as the foundation of a combination strategy for the functional cure of chronic hepatitis B. Brelovitug neutralizes and removes hepatitis B and hepatitis D virions and depletes HBsAg-containing subviral particles. In addition, brelovitug has shown it has the potential to be a potent immunomodulator.

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Media Contact

Derek Rapp

RiverVest Managing Director

314-726-6700

 

drapp@rivervest.com