Rare Daily Staff
Biogen has agreed to acquire Apellis Pharmaceuticals in a $5.6 billion cash deal that will add two commercially available immunology drugs to its portfolio and deepen its push into rare kidney and eye diseases.
The deal brings Biogen two complement-targeting therapies, Empaveli and Syfovre, that together generated $689 million in net product revenue in 2025 and are expected to grow at a mid- to high-teens rate at least through 2028, according to the companies. Biogen said the acquisition should strengthen its near- and long-term growth profile, with the transaction expected to become increasingly accretive to non-GAAP diluted earnings per share starting in 2027 and to meaningfully lift non-GAAP EPS growth through the end of the decade.
Biogen will pay $41 a share in cash for all outstanding Apellis stock, an 86 percent premium to its 90-day volume-weighted average share price. Apellis shareholders will also receive a nontransferable contingent value right, or CVR, that could pay up to an additional $4 a share if Apellis’ eye drug Syfovre meets global sales milestones between 2027 and 2031.
Biogen plans to finance the acquisition with a combination of cash and new debt and said it expects to fully de-lever by the end of 2027, preserving flexibility for additional deals. The transaction, approved by both companies’ boards, will be carried out through a tender offer followed by a second-step merger and is expected to close in the second quarter of 2026, subject to customary conditions and regulatory approvals.
Empaveli, sold as Aspaveli outside the United States, is a targeted C3 inhibitor approved by the U.S. Food and Drug Administration to treat adults with a rare blood disease called paroxysmal nocturnal hemoglobinuria (PNH). It is currently the only FDA‑approved treatment for PNH and works by blocking part of the immune system that can mistakenly attack red blood cells.
In a phase 3 clinical trial in people with certain rare kidney diseases (C3 glomerulopathy and primary immune‑complex membranoproliferative glomerulonephritis), pegcetacoplan reduced protein in the urine by about 68 percent and helped keep kidney function stable compared with placebo. These kidney uses are still being studied, including in children and in people whose C3G has come back after a kidney transplant, and are not yet approved.
Syfovre, also a C3-targeting therapy, is the first approved treatment for geographic atrophy, an advanced form of age-related macular degeneration that is a leading cause of blindness, and was cleared based on phase 3 studies showing reduced lesion growth and increasing benefit over time.
Biogen said Apellis’ commercial infrastructure, including its nephrology field force, will help accelerate launch preparations for felzartamab, the company’s experimental anti-CD38 antibody now in phase 3 trials in three kidney diseases, with the first pivotal readout expected in the first half of 2027.
“The addition of Apellis expands our growth portfolio in immunology and rare disease with two approved, best-in-class medicines that complement our existing portfolio,” Biogen President and CEO Christopher Viehbacher said. He added that Apellis’ talent and expertise will help build Biogen’s emerging nephrology franchise and reach more patients with immune-mediated retinal disease.
Photo: Biogen President and CEO Christopher Viehbacher
Stay Connected
Sign up for updates straight to your inbox.