Biogen To Acquire Apellis For $5.6 Billion, Expanding Complement Therapy Portfolio, Strengthens Growth Strategy

Biogen Inc. has announced a definitive agreement to acquire Apellis Pharmaceuticals, Inc. for approximately $5.6 billion. Under the deal, Apellis shareholders will receive $41 per share in cash, along with contingent value rights (CVRs) tied to future sales milestones of SYFOVRE®. The transaction is expected to close in the second quarter of 2026.

The acquisition is set to strengthen Biogen’s growth portfolio by adding two commercialised therapies, EMPAVELI® and SYFOVRE®, which together generated $689 million in revenue in 2025. These complement-targeting therapies address rare and immunological diseases, with projected growth in the mid-to-high teens through 2028. Apellis also brings an established U.S. commercial infrastructure, which is expected to support Biogen’s pipeline, including late-stage kidney disease programs.

“Consistent with our strategy, this acquisition immediately advances Biogen’s ongoing transformation. The addition of Apellis expands our growth portfolio in immunology and rare disease with two approved, best-in-class medicines that complement our existing portfolio and bolsters our near-and long-term growth potential,” said Christopher A. Viehbacher, Biogen’s President and Chief Executive Officer. “We look forward to welcoming Apellis employees to Biogen. We believe our combined capabilities and experience will allow us to maximize the potential of SYFOVRE® and EMPAVELI®, while Apellis’ talent, expertise and field capabilities will further strengthen Biogen, deepening the foundation for our growing nephrology franchise with felzartamab and serving many more patients with immune-mediated retinal disease."

EMPAVELI® (pegcetacoplan) is approved for rare kidney diseases such as C3 glomerulopathy and primary IC-MPGN, as well as paroxysmal nocturnal hemoglobinuria. Meanwhile, SYFOVRE® is approved for geographic atrophy linked to age-related macular degeneration and has demonstrated sustained efficacy in reducing lesion progression. Both therapies target the complement system, a key component of immune regulation.

“I am incredibly proud of the Apellis team and what we have achieved, including bringing two transformational medicines – SYFOVRE® and EMPAVELI® – to patients and building an innovative pipeline leveraging our deep expertise in complement science,” said Cedric Francois, M.D., Ph.D., co-founder and Chief Executive Officer of Apellis. “With Biogen’s extensive experience with immunology and rare disease, we believe this transaction will accelerate our impact and enable us to reach more patients. This transaction represents a compelling outcome for our shareholders and a strong validation of our strategy, scientific innovation, and execution.” 

Upon completion, the deal is expected to enhance Biogen’s revenue and earnings growth, becoming accretive to earnings per share starting in 2027. The company plans to finance the acquisition through a mix of cash and debt, aiming to reduce leverage by the end of 2027 while maintaining flexibility for future investments.