Bluejay Therapeutics, founded in 2021, was developing brelovitug, a fully human monoclonal antibody with Breakthrough Therapy and PRIME designations for chronic hepatitis delta virus (HDV).

At the time of acquisition by Mirum Pharmaceuticals, brelovitug was being evaluated in the AZURE Phase 3 registrational program for HDV, the most severe form of viral hepatitis. HDV occurs in people already infected with hepatitis B; nearly half of those affected progress to liver-related death within 10 years of diagnosis due to rapid progression to fibrosis, cirrhosis, hepatic decompensation and an increased risk of liver cancer.

RiverVest Fund V  

Co-led $20 million Series A in 2021

Participated in $41 million Series B in 2022

Participated in $182 million Series C in 2024

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Acquired by Mirum Pharmaceuticals in 2026 (Nasdaq: MIRM)