Biogen is buying RayThera in a deal valued at up to $1 billion to add early-stage immunology assets to its pipeline, the companies said. RayThera’s lead candidate is positioned to enter Phase I in early Q3 2026, giving Biogen a near-term shot at advancing a new immunology program into humans. Biogen said the transaction will bring a suite of anti-inflammatory small-molecule candidates addressing immune-mediated conditions across multiple therapeutic areas. RayThera’s shareholders are set to receive an undisclosed upfront payment, with the remainder of the consideration tied to clinical and regulatory milestones. The acquisition follows Biogen’s immunology expansion via its $5.6 billion purchase of Apellis, and it adds an alternative mechanism set to complement complement C3 inhibition with broader immunology exposure.