Biogen Inc. has agreed to acquire Apellis Pharmaceuticals Inc. for $5.6 billion, in a move that significantly expands its presence in immunology and rare diseases. The Biogen to Acquire Apellis deal stands among the company’s largest transactions to date, reinforcing its efforts to diversify beyond its core therapeutic areas.
As part of the agreement, the Cambridge, Massachusetts-based biotech company will pay $41 a share for Apellis. The acquisition brings two approved therapies into Biogen’s portfolio. Syfovre, Apellis’ top-selling drug, is used to treat an immune disorder that is a leading cause of blindness and generated $587 million in revenue last year. The second drug, Empaveli, is indicated for both a blood disorder and rare kidney diseases, with more than $100 million in sales recorded last year. These additions align with Biogen’s increasing focus on expanding its treatment footprint in complex disease segments. The Biogen to Acquire Apellis transaction also strengthens its commercial and therapeutic positioning in these areas.
The deal comes as Biogen seeks new growth drivers. Chief Executive Officer Chris Viehbacher has been working to offset declining performance in the company’s multiple sclerosis portfolio while navigating a slower-than-expected rollout of its Alzheimer’s treatment. In recent years, Biogen has pursued targeted acquisitions to strengthen its pipeline. Its $7.3 billion purchase of Reata Pharmaceuticals Inc. in 2023 added Skyclarys, the first approved treatment for Friedreich’s ataxia, a rare neurological disorder. This was followed by the acquisition of Human Immunology Biosciences Inc. for as much as $1.8 billion, bringing in felzartamab, a drug currently being evaluated for rare kidney diseases.
In addition to product gains, the Apellis acquisition provides Biogen with established commercial infrastructure, which is expected to support the potential launch of felzartamab if approved. The company has also been increasing its focus on early-stage immunology research, a segment known for high-value therapies such as AbbVie Inc.’s Humira.
