Biogen adds more immune drugs in $1B buyout of secretive startup Raythera

Dive Brief:

Biogen plans to buy startup RayThera to gain access to a portfolio of immunology drug candidates, including one slated to enter the clinic in the third quarter.
Founded in 2023, RayThera says its mission is to develop safer, more effective therapies for immunological diseases. But the company has said little publicly about what it’s doing. RayThera’s website doesn’t detail what it’s been working on, instead touting the company’s “nimble and adaptable approach” and containing a pipeline page with three prospects listed only as “anti-inflammatory.”
The deal with Biogen is also rather opaque, per a statement released Wednesday. RayThera investors will get an undisclosed upfront payment and could reap as much as $1 billion if unspecified clinical and regulatory goals are met.

Dive Insight:

The takeover represents the latest push by Biogen into immunology, expanding beyond its traditional stronghold in neurology medicines. The company is fresh off a $5.6 billion purchase of Apellis Pharmaceuticals, gaining two marketed products and a range of early-stage research projects.

Apellis focuses on a specific protein involved in the “complement” part of the immune system, which helps the body protect against disease. In developing drugs that block the protein, known as C3, researchers hope to stop the complement system from going into overdrive, causing diseases that attack healthy tissue instead of pathogens.

RayThera may offer other ways to fight immune system diseases. A patent search for “RayThera” turns up applications that cover TNF activity modulators, CCR4 inhibitors, STAT6 modulators and JAK2 V617F inhibitors. The list contains popular targets; AbbVie’s top-selling Humira medicine is a TNF blocker, while companies including Sanofi and Kymera Therapeutics are taking on STAT6.

Qing Dong and Gene Hung co-founded RayThera after selling a previous venture, XinThera, to Gilead Sciences in May 2023. In 2025, the company raised $110 million in a Series A financing led by Foresite Capital and OrbiMed Advisors. Without offering details, the press release from the funding round quoted Foresite partner Michael Rome saying he was “impressed with the progress” made by RayThera so quickly.

The purchase of RayThera reflects Biogen’s desire to fill out earlier stages of its pipeline after the Apellis deal. Biogen will lead development, manufacturing and globalization of the immunology candidates after the close of the transaction, which is expected to come in the third quarter.