Biogen Inc. has entered into a definitive agreement to acquire Massachusetts-based Apellis Pharmaceuticals, Inc. (NASDAQ: APLS) for USD 41.00 per share in cash, representing an upfront equity consideration of approximately USD 5.6 billion, plus contingent value rights tied to Syfovre net sales milestones. The transaction consolidates two FDA-approved complement component 3 (C3) inhibitors into Biogen's immunology and rare disease portfolio while providing an established US nephrology sales infrastructure and capabilities that Biogen believes will help support felzartamab, its Phase III kidney disease asset with a first readout expected in the first half of 2027.
Pegcetacoplan and the C3 complement inhibition platform
Both commercial assets acquired in this transaction — Syfovre (pegcetacoplan injection, intravitreal) and Empaveli (pegcetacoplan, subcutaneous) — share the same active molecule and mechanism of action. Pegcetacoplan is a pegylated cyclic peptide that selectively binds complement component C3, the central convergence node of all three complement activation pathways: classical, lectin, and alternative. By inhibiting C3 upstream, the therapy provides broad suppression of complement-mediated tissue injury without targeting a single downstream effector, which distinguishes it from C5-targeting agents that leave proximal complement activity intact.
Syfovre became the first therapy to gain an FDA approval for geographic atrophy (GA) secondary to age-related macular degeneration in February 2023. In the Phase III OAKS and DERBY studies, intravitreal pegcetacoplan reduced GA lesion growth rate versus sham at 24 months, with the monthly dosing arm of DERBY demonstrating up to a 36% reduction in lesion growth between months 18 and 24. Five-year data from the GALE open-label extension study, presented in November 2025, indicated that Syfovre delayed GA lesion progression by approximately 1.5 years in patients with nonsubfoveal GA relative to sham or projected sham. Apellis has completed a clinical trial for a prefilled syringe formulation and plans to submit an FDA application in the first half of 2026. Biogen acquires full global rights to Syfovre.
Empaveli holds FDA approval across three indications: paroxysmal nocturnal hemoglobinuria (PNH) in adults; C3 glomerulopathy (C3G) in patients aged 12 years and older; and primary immune-complex membranoproliferative glomerulonephritis (IC-MPGN) in patients aged 12 years and older. In the Phase III VALIANT study, Empaveli produced a 68% reduction in proteinuria, stabilized kidney function, and achieved substantial clearance of C3 deposits by biopsy in patients with C3G and primary IC-MPGN, including those with post-transplant C3G disease recurrence. Empaveli is the only FDA-approved treatment for pediatric patients aged 12 and older with C3G, the only approved therapy for post-transplant C3G recurrence, and the first approved treatment for both adult and pediatric populations in primary IC-MPGN. Ex-US commercialization rights for systemic pegcetacoplan are retained by Sobi under a pre-existing collaboration agreement; Biogen confirmed it will continue that relationship post-close.