Biogen has agreed to acquire Apellis Pharmaceuticals, a commercial-stage bio/pharmaceutical company, for $5.6 billion to expand its position in immunology, rare diseases, and nephrology (i.e., kidney disease).   

The acquisition brings two commercial immunology products to Biogen: Empaveli (pegcetacoplan), FDA-approved in three indications, including two rare kidney diseases, and Syfovre (pegcetacoplan injection), FDA-approved in geographic atrophy, an immune-mediated retinal disease. Net product revenue in 2025 for Empaveli and Syfovre together was $689 million, expected to grow at a rate in the mid-to-high teens at least through 2028, according to information from Biogen. The acquisition also included felzartamab, currently in Phase III development, which further positions Biogen in nephrology. 

Empaveli is a targeted C3 therapy designed to regulate excessive activation of the complement cascade, a part of the body’s immune system. It has been approved with a broad label for adults and adolescents with C3 glomerulopathy (C3G)  (glomerulopathy refers to diseases that damage the glomeruli, small blood vessels in the kidneys that filter waste and fluids) or primary IC-MPGN (primary immune-complex membranoproliferative glomerulonephritis) that also includes data on patients with post-transplant C3G disease recurrence. Syfovre is an approved therapy for geographic atrophy (GA) secondary to age-related macular degeneration. Geographic atrophy is an advanced, progressive form of dry age-related macular degeneration. 

Under the agreement, Biogen will commence a tender offer to acquire all of the outstanding shares of Apellis common stock for $41 per share in cash at representing an upfront equity consideration of approximately $5.6 billion and a contingent value right (CVR) per share payable upon achievement of certain thresholds related to global net sales of Syfovre. Upon the successful completion of the tender offer, Biogen will acquire all remaining Apellis shares that are not tendered into the tender offer through a second-step merger at the same consideration. 

The transaction, which was approved by the Boards of Directors of both companies, is subject to successful completion of the tender offer, customary closing conditions, and the receipt of necessary regulatory approvals. The acquisition is expected to close in the second quarter of 2026. 

Source: Biogen