FDA Approves New High Dose Regimen of SPINRAZA® (nusinersen) for Spinal Muscular Atrophy
Biogen announced that the U.S. Food and Drug Administration approved the High Dose Regimen of SPINRAZA® (nusinersen) for the treatment of spinal muscular atrophy, adding a new dosing option for the SMA community.
Biogen said the FDA approved the High Dose Regimen of SPINRAZA, comprised of 50 mg/5 mL and 28 mg/5 mL doses, for the treatment of spinal muscular atrophy.
Key facts
- The FDA approved the High Dose Regimen of SPINRAZA® (nusinersen) for spinal muscular atrophy.
- The regimen includes 50 mg/5 mL and 28 mg/5 mL doses.
- New patients can receive an accelerated loading phase with two 50 mg doses 14 days apart.
- Maintenance dosing is 28 mg every four months thereafter.
CAMBRIDGE, Mass., March 30, 2026 — Biogen Inc. today announced that the High Dose Regimen of SPINRAZA® (nusinersen), which is comprised of 50 mg/5 mL and 28 mg/5 mL doses, was approved by the U.S. Food and Drug Administration (FDA) for the treatment of spinal muscular atrophy (SMA). Backed by more than 10 years of clinical data supporting the Low Dose Regimen of SPINRAZA (12 mg), High Dose SPINRAZA was designed to deliver a higher concentration of drug through both the loading and maintenance dosing phases, to provide a new option in response to the ongoing needs of the community.
The High Dose Regimen of SPINRAZA, which will be available in the coming weeks, enables an accelerated loading phase for those new to SPINRAZA treatment — with two 50 mg doses administered 14 days apart — followed by 28 mg maintenance dose injections every four months thereafter. Patients transitioning from the Low Dose Regimen would follow their existing dosing schedule at four-month intervals after a single High Dose loading phase.
High dose nusinersen adds a new treatment option in SMA care
“Optimizing the dose of nusinersen builds on a therapy that we already know can change lives. The high dose regimen demonstrated meaningful clinical benefit while maintaining a well characterized safety profile,” said Richard Finkel, M.D., director, Center for Experimental Neurotherapeutics (CENT) at St. Jude Children’s Research Hospital. “I believe High Dose Spinraza will play an important role in the future of SMA care.”
The FDA approval is based on data from the three-part, Phase 2/3 DEVOTE study. Results from the pivotal cohort of the study showed treatment-naïve, symptomatic infants who received High Dose SPINRAZA experienced statistically significant improvements in motor function as measured by the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND), when compared to a prespecified matched sham (untreated) group from the ENDEAR study.
According to the data, the mean difference was 26.19 points, with scores of +15.1 versus -11.1 and a p-value of less than 0.0001. These findings support the clinical relevance of the High Dose Regimen and reinforce Biogen’s position that higher drug exposure may provide additional benefit for some people living with spinal muscular atrophy.
Biogen says more than 10 years of SPINRAZA data support the new regimen
“Over the past decade, Biogen has continued to listen, learn, and innovate to help advance care for people living with SMA,” said Priya Singhal, M.D., M.P.H., Executive Vice President and Head of Development at Biogen. “With more than 10 years of clinical data on SPINRAZA, the development of the High Dose Regimen reflects both the strength of that foundation and our unwavering commitment to the SMA community to optimize treatment options. We are grateful to the community for their support and contributions toward this milestone.”
In the DEVOTE study, the safety profile of the High Dose Regimen of SPINRAZA was generally consistent with the known safety of the Low Dose Regimen. The most common adverse reactions occurring in at least 10% of SPINRAZA-treated patients who received the High Dose Regimen and occurred at least 5% more frequently than in historic matched sham-control were pneumonia, COVID-19, pneumonia aspiration, and malnutrition in patients with infantile-onset SMA.
Biogen noted that COVID-19 was not discovered at the time of ENDEAR, the study from which the matched sham-control was taken. Even so, the company said the High Dose Regimen maintained a safety profile that was generally aligned with what clinicians already know from the Low Dose Regimen of SPINRAZA.
“Nearly ten years ago, the approval of SPINRAZA marked a turning point in SMA care and changed what the community believed was possible,” said Kenneth Hobby, President of Cure SMA. “Today’s approval of High Dose SPINRAZA makes progress in addressing unmet needs of the SMA community.”
Availability and global regulatory progress for High Dose SPINRAZA
Biogen said High Dose SPINRAZA will be available in the coming weeks. The company added that the new dosing option is also approved in the European Union, Switzerland, and Japan, and that it is working with regulatory authorities and national health authorities around the world to progress this additional dosing option for people living with SMA.
The latest approval therefore marks an important milestone not only for Biogen, but also for physicians, caregivers, patients and advocacy groups that have followed the evolution of SPINRAZA since its original introduction. By expanding the nusinersen dosing strategy with a newly approved high dose regimen, Biogen is positioning SPINRAZA as a more flexible treatment option in the long-term management of spinal muscular atrophy.
