Biogen Acquires Apellis for $5.6B in Rare Disease Push

Biogen Inc. is significantly bolstering its rare disease and immunology pipeline through a definitive agreement to acquire Apellis Pharmaceuticals, Inc. for an upfront sum of approximately $5.6 billion. This strategic move, valued at $41.00 per share in cash, also includes contingent value rights (CVRs) that could add up to an additional $4.00 per share, contingent on future sales performance of Apellis's geographic atrophy treatment, SYFOVRE. This acquisition signals Biogen's intent to accelerate its portfolio transformation and capture growth in underserved therapeutic areas.

The core of this transaction lies in Apellis's established complement cascade inhibitors. Biogen gains immediate access to EMPAVELI (pegcetacoplan), a therapy addressing rare kidney conditions like C3 glomerulopathy and paroxysmal nocturnal hemoglobinuria (PNH). Furthermore, the deal brings SYFOVRE (pegcetacoplan injection) into Biogen's fold, a groundbreaking therapy recognized as the first approved treatment for geographic atrophy linked to age-related macular degeneration. This condition represents a primary driver of vision impairment globally, highlighting the significant unmet medical need and market potential.

Combined, these two Apellis assets generated $689 million in revenue during 2025. Projections indicate a robust growth trajectory, with anticipated annual increases in the mid-to-high teens through 2028. This consistent revenue expansion is a key driver for Biogen, offering immediate contributions to its top line and a strong foundation for future earnings. The company anticipates the deal will become increasingly accretive to its non-GAAP diluted earnings per share starting in 2027, with a clear path to full de-leverage by the end of that same year.

Christopher Viehbacher, Chief Executive Officer of Biogen, emphasized that this acquisition is instrumental in advancing the company's ongoing strategic transformation. He highlighted the immediate expansion of Biogen's immunology capabilities and the reinforcement of its nephrology expertise. Echoing the strategic importance, Cedric Francois, CEO of Apellis, described the agreement as a highly favorable outcome for Apellis shareholders and a strong validation of the company's innovative approach and strategic execution in developing novel therapies.

The transaction is structured as a cash tender offer, which will be followed by a subsequent merger to complete the acquisition. Regulatory approvals are anticipated to be secured, with the deal expected to finalize in the second quarter of 2026. This timeline allows for thorough due diligence and regulatory review, ensuring a smooth integration of Apellis's assets and operations into Biogen's global infrastructure. The market for treatments targeting rare diseases and age-related conditions continues to expand, driven by aging populations and advancements in scientific understanding.

In facilitating this significant transaction, Biogen received financial advisory services from Lazard, with legal counsel provided by Cravath, Swaine & Moore LLP and Arnold & Porter. Apellis Pharmaceuticals was advised by Evercore on financial matters, and received legal counsel from Wachtell, Lipton, Rosen & Katz and WilmerHale. The involvement of these prominent advisory firms underscores the complexity and strategic importance of this deal within the biotechnology sector.