RayThera will bring three preclinical assets into the Biogen fold, all with anti-inflammatory activity. The most mature of these assets is expected to enter Phase 1 development in Q3.
Biogen, which has long practiced patience and discipline in its M&A strategy, will acquire private biotech RayThera for up to $1 billion in a deal that analysts say will expand the Massachusetts company’s footprint in immunology.
RayThera’s shareholders will receive an undisclosed payment to kick off the agreement, according to a Wednesday release. Clinical and regulatory milestones are also on the table, giving the takeover a total deal value of up to $1 billion. The companies expect to close the acquisition in the third quarter of this year.
Through RayThera, Biogen will get its hands on three anti-inflammatory therapies, all of which have yet to enter the clinic. The lead program is expected to enter Phase 1 studies in the third quarter. The deal matches an early-stage strategy that CEO Chris Viehbacher has signaled over the past few quarters.
Not much is known about RayThera’s pipeline assets, but according to the biotech’s website, it focuses on small-molecule drug development “with a mission to develop safer, more effective therapeutics to treat patients with immunological diseases.” In April 2025, RayThera raised $110 million in series A funds, drawing support from big investors like Foresite Capital and OrbiMed Advisors.
The acquisition of RayThera “present[s] a multi-indication opportunity across immune-mediated diseases, potentially complementing Biogen’s existing pipeline,” analysts at BMO Capital Markets told investors in a Wednesday note.
Biogen at present is anchoring its immunology push on three late-stage assets: the anti-CD40L dapirolizumab pegol for systemic lupus erythematosus (SLE), the BDCA2-targeting antibody litifilimab for SLE and cutaneous lupus erythematosus and the anti-CD38 antibody felzartamab for antibody-mediated rejection, IgA nephropathy and primary membranous nephropathy.
Of these, litifilimab has an upcoming and closely watched Phase 3 readout for SLE, according to BMO. Biogen is evaluating the asset in the late-stage TOPAZ-1 and TOPAZ-2 trials focusing on patients with active disease on background non-biologic therapies such as steroids and immunosuppressants. Data are anticipated in the fourth quarter, the analysts said.
The RayThera buy also follows Biogen’s $5.6 billion pickup of Apellis Pharmaceuticals in March—an acquisition that Viehbacher said at the time is “the best opportunity that really fits strategically with Biogen and where our pipeline is taking us.” Through Apellis, Biogen has gained two FDA-approved drugs in Syfovre, indicated for geographic atrophy secondary to age-related macular degeneration, and Empaveli, a kidney drug cleared for C3 glomerulopathy or paroxysmal nocturnal hemoglobinuria.
Biogen and Apellis closed the buyout last month.
Prior to the Apellis buy, analysts and investors had long questioned Biogen’s business development strategy, particularly for acquisitions. Viehbacher, who took over as CEO in 2022, had promised quarter after quarter that the company wasn’t in a hurry to buy. But that has shifted, with Viehbacher admitting in April that the early-stage pipeline needed a boost.
