Biogen (Nasdaq: BIIB) has completed its acquisition of Apellis Pharmaceuticals, adding two commercially approved complement inhibitors and an established nephrology infrastructure to its portfolio in a deal structured at USD 41 per share in cash plus a contingent value right of up to USD 4 per share tied to Syfovre (pegcetacoplan injection, intravitreal) annual net sales thresholds. The transaction, first announced in March, makes Apellis a wholly owned subsidiary of the Cambridge, Massachusetts-based company and positions Biogen to compete in complement-driven rare diseases across ophthalmology and nephrology.
Under the terms of the tender offer, approximately 105.7 million shares, representing roughly 82.4% of Apellis's outstanding stock, were validly tendered prior to the May 13, 2026 expiration. A Biogen subsidiary accepted those shares for payment before merging with and into Apellis, without a shareholder vote. Apellis shares ceased trading on Nasdaq upon deal close. The contingent value right, which is non-transferable, entitles holders to receive up to USD 4 per share in aggregate cash payments contingent on Syfovre reaching certain annual global net sales thresholds; those payments are not guaranteed.
The two assets at the center of the transaction are pegcetacoplan formulations targeting distinct disease settings. Syfovre (pegcetacoplan injection), delivered intravitreally, is the first approved therapy for geographic atrophy secondary to age-related macular degeneration and carries full global commercial rights with no pre-existing ex-US partnership encumbrances. Empaveli (pegcetacoplan), the systemic formulation, is approved in the US for paroxysmal nocturnal hemoglobinuria and, more recently, for C3 glomerulopathy and primary immune complex membranoproliferative glomerulonephritis in patients 12 years and older. Outside the US, Swedish Orphan Biovitrum retains exclusive commercialization rights to the systemic product under a pre-existing collaboration, where it is marketed as Aspaveli. Biogen acquires full US rights to Empaveli and inherits the Sobi partnership for ex-US territories. Together, the two products recorded USD 689 million in net product revenue in 2025.
Both products act on the complement cascade via C3, the central convergence point of the classical, lectin, and alternative complement pathways. By targeting C3 rather than downstream effectors such as C5, pegcetacoplan is designed to provide broader upstream control of complement activation. That mechanistic positioning is central to Apellis's complement-driven diseases franchise and differentiates it from the C5-targeting agents that have historically dominated the complement inhibitor market. The nephrology approvals for Empaveli in C3G and IC-MPGN, conditions in which approximately 50% of patients progress to kidney failure within five to ten years of diagnosis, extend pegcetacoplan's commercial reach beyond the ophthalmology setting and into a rare disease space where treatment options remain limited.