Biogen announced it will acquire San Diego-based RayThera in a transaction valued at up to $1 billion, aiming to strengthen its immunology pipeline with small-molecule anti-inflammatory assets. Biogen will provide an undisclosed upfront payment, with the remainder of total consideration tied to future clinical and regulatory milestones. RayThera’s lead candidate is expected to enter Phase I clinical development in early Q3 2026, giving Biogen a near-term timeline to generate human data on the program. RayThera, founded by Qing Dong and Gene Hung, previously raised $110 million in a Series A round and built a focused immunology small-molecule portfolio. The acquisition aligns with Biogen’s pipeline diversification strategy and follows other immunology moves earlier this year, including Biogen’s decision to acquire Apellis for $5.6 billion. Biogen expects the RayThera deal to close in Q3 2026.