Biogen is an established biopharmaceutical company focused on treatments for neurological diseases and rare diseases. Its declining multiple sclerosis franchise is its largest revenue generator and contributed 45% of total revenue in 2024. Biogen also generates significant revenue from its CD20 collaboration agreements with Roche (18% of total in 2024), which includes oncology drugs Rituxan and Gazyva and multiple sclerosis drug Ocrevus. Biogen's newer franchises include Spinraza (spinal muscular atrophy, with partner Ionis), Leqembi (Alzheimer's disease, collabroation revenue from its partner Eisai), Skyclarys (Friedreich's ataxia, Reata), Zurzuvae (postpartum depression, Sage), and Qalsody (amyotrophic lateral sclerosis, Ionis).