The Rare Disease Star Fostered by the FDA: Implications of the Apellis Acquisition

U.S. Food and Drug Administration approval in July 2025 of EMPAVELI (pegcetacoplan) for C3 glomerulopathy (C3G) and immune-complex membranoproliferative glomerulonephritis (IC-MPGN) has once again focused attention on Apellis Pharmaceuticals, Inc. (APLS), a U.S. rare-disease biotech. EMPAVELI, first approved in 2021 for paroxysmal nocturnal hemoglobinuria (PNH), has strengthened Apellis’s position in the complement C3 inhibitor field, while its intravitreal therapy SYFOVRE won its initial FDA nod in 2023 for geographic atrophy (GA). Alongside these approvals, the FDA has mandated label warnings for serious ophthalmic risks such as retinal vasculitis, reflecting a rigorous safety-management approach. Apellis’s portfolio is thus regarded as a “high-risk, high-value” lineup in the rare-disease arena.

Based in Waltham, Massachusetts, Apellis specializes in complement C3 inhibition, building a pipeline across hematology, ophthalmology and nephrology. Centered on SYFOVRE and EMPAVELI, the company has launched commercial operations in the U.S. and Europe. In 2025, Apellis reported total revenues of $1.0 billion and net product revenues of $689 million—year-over-year growth that drove its first full-year profitability, delivering net income of $22.4 million. With SYFOVRE holding roughly 60% of the GA market, Apellis is advancing additional indications for both products and preparing clinical programs for next-generation complement inhibitors.

Highlighting this track record and growth potential, Biogen Inc. (BIIB) agreed on March 31, 2026 to acquire Apellis. On April 14, through its subsidiary Aspen Purchaser Sub, Biogen launched a tender offer of $41.00 in cash per share plus up to $4.00 in non-transferable contingent value rights (CVRs). After the minimum tender condition was met, Biogen purchased all validly tendered shares on May 14 and completed a merger under Section 251(h) of the Delaware General Corporation Law, making Apellis a wholly owned Biogen subsidiary. A Schedule 13D/A filing with the U.S. Securities and Exchange Commission confirmed that this transaction constitutes the final exit from public reporting, resulting in the delisting of Apellis and Biogen’s acquisition of 100% of its outstanding shares.