The Food and Drug Administration approved a high-dose version of Biogen’s spinal muscular atrophy drug Spinraza on Mar. 30, allowing for a new dosing regimen for patients starting the treatment.
The approval enables patients new to Spinraza to receive two 50-mg loading doses spaced two weeks apart, followed by maintenance injections every four months. Previously, the original formulation required four induction doses. Biogen said the higher dose will be available in the coming weeks.
Analysts from Jefferies said that high-dose Spinraza “could help sustain sales, effectively bridging [Biogen’s] $1.5B+ SMA franchise toward next-gen salanersen.” Salanersen is an investigational antisense oligonucleotide currently in Phase 1b development with late-stage data expected as early as 2028. BMO Capital Markets also commented on the approval: “While we are more interested in future updates from the company’s next-generation salanersen agent, approval of high-dose Spinraza is a meaningful first step in continuing to stabilize and grow the company’s SMA products.”
Spinraza was first approved in December 2016 and reached peak sales of $2.097 billion in 2019 before declining below $1.55 billion by 2025 following competition from Roche's oral Evrysdi formulation. Biogen CEO Chris Viehbacher said during a February earnings call that this new approval could help strengthen those numbers.
Monday’s decision was supported by results from the Phase 2/3 DEVOTE study, which showed improved motor skills over sham control and some improvement over standard-dose Spinraza, though not statistically significant for all measures. Updated data presented at this year’s Muscular Dystrophy Association congress confirmed significant benefits regarding motor function, event-free survival, and neurofilament light chain levels.
Richard Finkel, director of the Center for Experimental Neurotherapeutics at St. Jude Children’s Research Hospital, said Monday that “the approval of high-dose Spinraza builds on a therapy that we already know can change lives,” adding it demonstrated “meaningful clinical benefit” while maintaining a well characterized safety profile.
