Biogen Inc. and Apellis Pharmaceuticals, Inc. announced in a press release the companies have entered into a definitive agreement under which Biogen has agreed to acquire all outstanding shares of Apellis for $41.00 per share in cash at closing, or approximately $5.6 billion. According to the press release, the addition of Apellis is expected to enhance Biogen’s short-term and long-term revenue growth profile by adding 2 commercialized differentiated immunology and rare disease medicines to its growth portfolio—Syfovre and Empaveli. 

Syfovre is FDA-approved for geographic atrophy secondary to age related macular degeneration. Apellis has completed a clinical trial for a Syfovre prefilled syringe and plans to submit its application for FDA approval in the first half of 2026. Empaveli is FDA approved in rare immune-mediated kidney diseases and in paroxysmal nocturnal hemoglobinuria.

Apellis brings an established US sales infrastructure and capabilities, including in nephrology, that Biogen said it believes will accelerate and strengthen Biogen’s commercial readiness for felzartamab, which is currently in phase 3 studies for 3 kidney diseases with the first trial readout expected in the first half of 2027. Upon closing of the transaction, expected in the second quarter of 2026, the addition of Apellis is expected to add commercial products to Biogen that together recorded $689 million in revenue in 2025, and which are expected to grow at a rate in the mid-to-high teens at least through 2028, the press release stated.

“Consistent with our strategy, this acquisition immediately advances Biogen’s ongoing transformation," said Christopher A. Viehbacher, Biogen’s president and chief executive officer, in the press release. "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. 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."

Cedric Francois, MD, PhD, cofounder and chief executive officer of Apellis, also added: “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. 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.”