Biogen buys Apellis for $5.6B to bolster immunology and kidney disease pipeline
What's the deal? Cambridge, Massachusetts-based BiogenDealroom has a profile for this one. Try Dealroom → has agreed to acquire Waltham-based Apellis Pharmaceuticals for $5.6 billion, or $41 per share — more than double Apellis' closing share price on March 30, 2026.
The deal is expected to close in the second quarter of 2026, after which a significant proportion of Apellis' 733 employees will join Biogen.
With the acquisition, Biogen gains two approved drugs. Syfovre, approved in 2023, treats geographic atrophy — an immune-driven condition that destroys retinal cells and causes vision loss — and generated $587 million in revenue in 2025. Empaveli, first approved in 2021, treats a rare blood disorder and two rare kidney diseases, and generated $102 million in 2025. Together the drugs brought in $689 million in combined net sales in 2025.
Why now? Biogen chief executive officer Chris ViehbacherDealroom has a profile for this one. Try Dealroom → has been aggressively rebuilding its pipeline through acquisitions as its multiple sclerosis franchise declines and its Alzheimer's drug gets off to a slow start.
The Apellis deal adds near-term revenue from two approved drugs and brings a US sales infrastructure and nephrology expertise that Biogen needs to launch felzartamab — its own kidney disease drug currently in Phase 3 trials, with first results expected in the first half of 2027.
Apellis' stock had fallen 32% in 2026 before the deal, making it an attractively priced target.
What could go wrong? Syfovre had a troubled start — in 2023, Apellis laid off 225 people amid safety concerns raised by some experts about the drug. Though it has since recovered strongly, those concerns have not been forgotten. Felzartamab, the drug Biogen is banking on for future kidney disease revenue, has yet to read out Phase 3 data, leaving significant clinical and regulatory uncertainty ahead.
At $5.6 billion upfront, Biogen is paying roughly eight times Apellis' 2025 combined net sales — a premium that requires both existing drugs to keep growing and felzartamab to succeed.
The signal: Biogen's acquisition reflects a broader strategic imperative facing large pharma: buy approved revenue now to buy time for the pipeline.
Immunology has emerged as one of the most commercially productive fields in drug development, with blockbusters like AbbVieDealroom has a profile for this one. Try Dealroom →'s Humira setting the template. Biogen is betting that drugs targeting the immune complement pathway represent the next wave of that opportunity. The kidney disease angle is particularly notable: rare nephrology is fast becoming one of the most competitive and capital-intensive battlegrounds in biopharma.
Sources:
Apellis Pharmaceuticals
Biogen
Reuters
Biopharma Dive
Fierce Pharma
BioSpace
Business Journals
Stat News
Bloomberg
Image credit:
Apellis Pharmaceuticals
J.V.
