Changes in the treatment of spinal muscular atrophy

January 12, 2026. Biogen announced that the European Commission (EC) has granted marketing authorization for the higher-dose regimen of the drug nusinersen, comprising doses of 50 mg/5 ml and 28 mg/5 ml, for the treatment of spinal muscular atrophy (SMA) 5q.

Spinal muscular atrophy (SMA) 5q is the most common form of the disease and accounts for about 95% of all SMA cases. The marketing authorization for the drug nusinersen in the European Union has been updated with a higher-dose treatment regimen. The new higher-dose regimen includes faster saturating doses: two doses of 50 mg 14 days apart, followed by maintenance doses of 28 mg given every four months. Patients transitioning from a 12 mg dose will receive a single 50 mg dose instead of another 12 mg dose, followed by 28 mg maintenance doses every four months. Nusinersen is intended to be administered intrathecally, by lumbar puncture performed by medical personnel experienced in performing such procedures.

"Since it was approved for marketing in the European Union in 2017, the drug nusinersen has helped set a new standard of patient care and has been used to treat more than 10,000 infants, children, adolescents and adults worldwide," - said Priya Singhal, M.D., M.P.H., Executive Vice President and Chief Development Officer at Biogen. "We are proud to introduce a treatment regimen with higher doses of the drug nusinersen, which we developed in response to the changing needs of people living with SMA. We are deeply committed to making it available to the European SMA patient community as soon as possible. We are grateful for the contributions of the entire SMA community that made today's approval possible."

The marketing authorization issued by the European Commission is based on data from the three-part Phase 2/3 DEVOTE study and its ongoing long-term extension phase. Results from the study's pivotal cohort showed that symptomatic infants who were previously untreated and received higher doses of nusinersen had statistically significant improvements in motor function on the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) scale, compared to a pre-specified matched control (untreated) group from the ENDEAR* study (mean difference: 26.19 points; +15.1 versus -11.1, p<0.0001). Improvements in motor function were also noted in an open-label cohort of patients across a broad spectrum of ages and with different types of SMA who switched from the standard-dose (12mg) treatment regimen. In these participants, a mean improvement in Hammersmith Functional Motor Scale - Expanded scores was observed, by 1.8 points [SD 3.99] from baseline to day 302.1

"The results of the DEVOTE study provide promising evidence that this new dosing option can lead to clinically meaningful treatment effects with a safety profile broadly consistent with that defined for the 12 mg dose," - stated Eugenio Mercuri, MD, PhD and Professor of Child Neurology at the Catholic University of Rome, Italy. "I have witnessed remarkable advances in the treatment of SMA, but it is still clear that the challenges have not gone away. The European Commission's approval of a treatment regimen with the drug nusinersen at higher doses is an important step toward addressing these challenges and further improving care for people living with SMA."

During the study, the higher-dose regimen was generally well tolerated, and reported adverse events were consistent with the course of SMA and with the established safety profile of nusinersen. In the long-term, extended phase of the study with continued use of higher doses of nusinersen, no new safety concerns were observed. In the DEVOTE trial, the most common adverse events, which occurred in at least 10% of participants treated with the higher-dose regimen and at least 5% more often than in the matched placebo group, were pneumonitis, COVID-19 infection, pharyngitis and malnutrition.

Special warnings and precautions for the use of nusinersen include side effects associated with lumbar puncture surgery, low platelet count and blood clotting disorders, nephrotoxicity and hydrocephalus (excessive accumulation of cerebrospinal fluid in the brain).

"As a community, we welcome progress that expands the options available to patients and reinforces further innovation in SMA care," - Nicole Gusset, President of SMA Europe, said. "This decision underscores the importance of long-term research and continued investment contributing to an expanding array of options that, over time, will provide the opportunity for a more personalized approach to care for people with SMA."

The updated Summary of Product Characteristics will be available on the European Medicines Agency website, at the link www.ema.europa.eu. 

The treatment regimen with higher doses of the drug nusinersen is also approved for use in Japan. It is also currently being evaluated by the U.S. Food and Drug Administration (FDA), with a decision expected by April 3, 2026. Biogen is working with regulators around the world to make this additional dosage option available to people living with SMA as soon as possible. 

*ENDEAR is one of the two key studies that gave rise to the approval of the drug nusinersen 12 mg.

Source: Press Release