Biogen agreed to acquire Apellis Pharmaceuticals in a $5.6 billion deal, stepping up its strategy to broaden commercialized immunology offerings and accelerate growth in nephrology. The acquisition adds Apellis’ approved complement medicines Empaveli and Syfovre, extending Biogen’s presence in immune-mediated rare disease and retinal care. Financial disclosures point to a contingent value right (CVR) tied to Syfovre sales milestones, with Biogen planning to fund the transaction through a mix of cash and borrowings and target de-leveraging by the end of 2027. The deal also signals how quickly Biogen is acting to rebuild momentum after earlier portfolio moves, with management framing Apellis as immediately additive to launch readiness for pipeline assets including felzartamab.