Biogen to buy Apellis

Biogen agreed on March 31 to buy Apellis Pharmaceuticals for about $5.6 billion in cash, adding eye, blood, and kidney disease drugs to its lineup. (biogen.com) Under the deal, Apellis shareholders will get $41 a share at closing, plus contingent value rights worth up to $4 a share tied to 2027 net sales of Syfovre, Apellis’s eye drug. The companies said the transaction is expected to close in the third quarter of 2026, subject to shareholder and regulatory approvals. (biogen.com) Apellis brings two approved pegcetacoplan medicines. Syfovre is cleared in the United States for geographic atrophy, an advanced form of age-related macular degeneration, and Empaveli is approved for paroxysmal nocturnal hemoglobinuria, a rare blood disorder. (accessdata.fda.gov, dailymed.nlm.nih.gov) Empaveli also won a broader kidney indication in 2025 for patients age 12 and older with C3 glomerulopathy or primary immune-complex membranoproliferative glomerulonephritis, to reduce proteinuria. Those diseases are driven by overactivity in the complement system, part of the immune system that helps the body attack threats. (accessdata.fda.gov) Biogen said the acquisition will push it deeper into immunology and rare disease as it expands beyond its older multiple sclerosis business. In its 2025 results, the company said growth products rose 19% for the year and offset declines in multiple sclerosis products excluding Vumerity. (biogen.com, biogen.com) The market reaction was immediate. Apellis shares jumped 135% to $40.23 on March 31, while Biogen shares closed down 2.3%, according to Bloomberg. (bloomberg.com) Syfovre gives Biogen a foothold in geographic atrophy, a condition that slowly destroys cells in the retina and can take away central vision. The drug’s label also carries warnings about retinal vasculitis and retinal vascular occlusion, rare but severe eye complications that can cause major vision loss. (accessdata.fda.gov, pi.apellis.com) Apellis told investors in February 2025 that more than 510,000 Syfovre injections had been administered since launch through December 2024, including clinical trials, and that it delivered about 94,000 doses to physician practices in the fourth quarter of 2024. (apellis.com) For Biogen, the bet is that Apellis’s marketed drugs can add near-term revenue while giving the company a bigger position in kidney and ophthalmology markets. For Apellis, the standalone run ends with a sale at a premium after a year in which Syfovre’s commercial uptake and safety profile stayed under close watch. (biogen.com, statnews.com)