Biogen to acquire Apellis for USD 5.6 billion to strengthen immunology and rare disease portfolio

Biogen has agreed to acquire Apellis Pharmaceuticals in a USD 5.6 billion cash deal, adding two revenue-generating therapies to its portfolio. The transaction is expected to accelerate growth in immunology and rare diseases while enhancing Biogen’s commercial and pipeline capabilities.

Biogen Inc. has entered into a definitive agreement to acquire Apellis Pharmaceuticals for approximately USD 5.6 billion in cash, alongside contingent value rights tied to future sales performance of a key drug. The deal will bring two marketed therapies, targeting rare immune and retinal diseases into Biogen’s portfolio, with combined annual sales of USD 689 million in 2025 and projected double-digit growth through 2028, according to company disclosures. Biogen, a US-based biotechnology company focused on neurological, immunological, and rare diseases, is seeking to diversify its revenue base amid evolving competitive pressures.

Apellis Pharmaceuticals specializes in complement-based therapies, addressing conditions driven by immune system dysfunction. The acquisition strengthens Biogen’s position in high-value therapeutic areas, particularly immunology and nephrology, while expanding its commercial infrastructure in the United States. It also supports the development and future commercialization of late-stage pipeline assets, including kidney disease treatments currently in Phase 3 trials. For the broader industry, the transaction underscores ongoing consolidation in the biotechnology sector as firms seek scale, proven revenue streams, and specialized expertise.

Investors may view the deal as a strategic move to secure near-term revenue growth while mitigating risks associated with early-stage drug development. The inclusion of contingent payments linked to future drug sales reflects a structured approach to balancing valuation with performance outcomes.