The US Food and Drug Administration has approved a higher-dose version of Spinraza, a key therapy from Biogen Inc (NASDAQ:BIIB, XETRA:IDP) for spinal muscular atrophy (SMA), a move analysts at Jefferies say could help sustain the company’s long-standing position in the rare disease market.
According to the analysts, the decision was largely anticipated by investors despite earlier regulatory delays tied to manufacturing issues described as “benign.”
The newly approved regimen, often referred to as high-dose Spinraza, is expected to reinforce the durability of Biogen’s SMA franchise, which generates more than $1.5 billion annually.
Spinraza, also known as nusinersen, has been a cornerstone SMA therapy for years. The updated dosing approach includes larger loading doses followed by higher maintenance levels, which analysts say may address the “waning-off effect experienced by patients” and improve the overall durability of response. This could also expand uptake among adult patients, potentially shifting the product from a stabilization phase back toward growth in 2026 and beyond, they believe.
Jefferies analysts noted that the therapy’s rollout in Japan in late 2025 has already “tracked ahead of expectations,” with some patients reportedly switching back to Spinraza after trying alternative treatments. The high-dose version has also secured approvals in Europe and Switzerland, further strengthening its global footprint.
The approval comes as Biogen works to bridge its current SMA portfolio toward next-generation therapies, including salanersen, a once-yearly investigational treatment that could reach late-stage data readouts by 2028. The analysts view this transition as critical, suggesting that high-dose Spinraza could “effectively bridge” the existing franchise while newer innovations mature.
Beyond dosing improvements, Biogen is also investing in delivery technologies. Its acquisition of Alcyone Therapeutics in 2025 brought in the ThecaFlex system, a potential implant designed to simplify drug administration for chronic patients by reducing the need for repeated spinal injections. Approval for that system could come later in the decade.
Competition in the SMA market is expected to intensify, but analysts believe Spinraza’s position remains relatively strong. Data from a study involving apitegromab showed greater motor function improvement when used alongside Spinraza compared with Evrysdi, an oral therapy developed by Roche. Meanwhile, Roche has discontinued another SMA program, emugrobart, signaling challenges for some competing approaches.
Looking more broadly, Jefferies highlighted Biogen’s diverse commercial portfolio, including therapies such as Leqembi, Skyclarys, Zurzuvae, and Vumerity, as a foundation for potential stock gains over 2026 to 2027. The firm added that success in late-stage clinical programs could further support growth, noting that each has $1 billion+ in blockbuster potential.
“Ultimately, having one to two pipeline products approved should enable Biogen’s overall topline revenues to grow,” the analysts wrote, nothing this could be through internal development or business development deals. They added that management remains “opportunistic” in pursuing assets valued up to $5 billion to $6 billion.
While pricing details for high-dose Spinraza have not yet been disclosed, analysts suggested that improved efficacy, particularly in measures like event-free survival, could justify a premium, at least during the initial treatment phase, Jefferies added.
Shares of Biogen traded up 2% at $187 on Monday afternoon.