Mirum Pharmaceuticals agreed to acquire Bluejay Therapeutics for $620 million in cash and stock to gain brelovitug, a monoclonal antibody in Phase 3 targeting hepatitis D virus (HDV). Bluejay’s Phase 2 readout showed complete HDV RNA responses and liver enzyme improvements; Mirum expects top-line Phase 3 data in the second half of next year and is targeting a regulatory filing and commercial launch in 2027. The deal includes up to $200 million in sales‑based milestones and a concurrent private placement to raise roughly $200 million to support development and commercialization.