Biogen announced on June 18 that it will acquire private biotech company RayThera for up to $1 billion, a move analysts say will expand Biogen’s presence in immunology. The Massachusetts-based company said RayThera’s shareholders will receive an undisclosed initial payment, with additional payments tied to clinical and regulatory milestones. The companies expect the acquisition to close in the third quarter of this year.
Through the deal, Biogen will gain access to three anti-inflammatory therapies from RayThera, all of which are preclinical. The lead program is expected to enter Phase 1 studies in the third quarter. This approach aligns with CEO Chris Viehbacher’s strategy of focusing on early-stage assets over recent quarters.
RayThera specializes in small-molecule drug development aimed at treating immunological diseases. In April 2025, the company raised $110 million in series A funding from investors including Foresite Capital and OrbiMed Advisors.
Analysts at BMO Capital Markets said the acquisition “present[s] a multi-indication opportunity across immune-mediated diseases, potentially complementing Biogen’s existing pipeline.” Currently, Biogen is developing three late-stage assets: dapirolizumab pegol for systemic lupus erythematosus (SLE), litifilimab for SLE and cutaneous lupus erythematosus, and felzartamab for antibody-mediated rejection as well as kidney-related conditions. Of these programs, litifilimab has an upcoming Phase 3 readout anticipated later this year.
The purchase of RayThera follows Biogen’s $5.6 billion acquisition of Apellis Pharmaceuticals in March. That deal brought two approved medicines into Biogen's portfolio—Syfovre for geographic atrophy secondary to age-related macular degeneration and Empaveli for C3 glomerulopathy or paroxysmal nocturnal hemoglobinuria—and supported future launches within kidney disease research pipelines.
Viehbacher previously told investors that while Biogen had been cautious about acquisitions since he became CEO in 2022, recent changes were needed due to gaps identified within its early-stage pipeline.
