Mirum Pharmaceuticals agreed to acquire Bluejay Therapeutics for $620 million upfront to obtain brelovitug, a monoclonal antibody in late‑stage development for chronic hepatitis D. The deal accelerates Mirum’s viral hepatitis portfolio and secures a near‑term commercial asset if the antibody wins approval. The acquisition transfers late‑stage development costs and regulatory risk to Mirum while offering Bluejay shareholders a sizable exit. For payers and physicians, a new hepatitis D therapy would address an unmet need in a disease with limited treatment options; regulators will focus on durable viral suppression and safety in advanced liver disease.