Nusinersen Data Reinforces Biogen’s Dedication to SMA Outcome Improvement Through Clinical Research

CAMBRIDGE, Mass., June 27, 2025 – Biogen Inc. (BIIB) is bolstering its position in the spinal muscular atrophy (SMA) treatment landscape with compelling new data showcased at the SMA Research & Clinical Care Meeting hosted by Cure SMA in Anaheim, California. The findings, stemming from the DEVOTE and NURTURE trials, further underline the clinical impact of nusinersen, marketed as SPINRAZA®, across a broad spectrum of SMA patients. Biogen is currently navigating regulatory reviews for a higher dose regimen of nusinersen in the U.S., Europe, Japan, and other global markets, setting the stage for potentially enhanced treatment outcomes.

“As the SMA treatment landscape continues to evolve, we remain steadfast in our commitment to address the unmet needs of the community. The findings from Part C of the DEVOTE study further strengthen the growing body of evidence supporting the potential benefits of the higher dose regimen of nusinersen,” said Stephanie Fradette, Pharm.D., Head of the Neuromuscular Development Unit at Biogen.

Higher Dose Regimen Shows Promise for Previously Treated Patients

Part C of the DEVOTE study offers a significant look at how nusinersen’s investigational higher dose regimen performs in those already on the established 12 mg dose for an average of nearly four years. The trial enrolled 38 patients, aged 4 to 65, with half being ambulatory. Under the new protocol, participants received an initial 50 mg dose followed by 28 mg every four months. The results are encouraging.

The majority of participants saw functional improvements, reflected in the Hammersmith Functional Motor Scale – Expanded (HFMSE), Revised Upper Limb Module (RULM), and Clinical Global Impression of Change (CGI-C). These improvements spanned different patient profiles, functional statuses, and age groups. Non-ambulatory participants, for instance, registered an average increase of +2.5 on the HFMSE, while ambulatory participants saw an increase of +1.1.

“These emerging data indicate that additional gains in function might be possible even in those with established disease who have been on therapy for years,” noted Dr. Richard Finkel, director, Center for Experimental Neurotherapeutics (CENT) at St. Jude Children’s Research Hospital. “This effort to optimize the dosing of SPINRAZA is very exciting for the field and could fundamentally change how we treat our patients.”

The higher dose regimen presented a safety profile broadly consistent with the existing 12 mg SPINRAZA regimen. Reported adverse events, including pneumonia and respiratory issues, were within the generally accepted safety parameters. Serious adverse events were observed in just six participants, but these were not linked to the treatment.

NURTURE Study’s Final Data Drive Home the Value of Early Intervention

The eight-year NURTURE study, the final results of which are now available, strengthens the value of early intervention with 12 mg SPINRAZA in clinically presymptomatic infants. This long-term data underscores the benefits of initiating treatment before symptoms manifest.

At the study’s conclusion, all 25 children in NURTURE were alive and demonstrating continued clinical benefits. The vast majority did not require ventilators. Impressively, 92% of these young participants achieved independent walking, many within normal developmental timelines. The study also provided a strong link between elevated levels of neurofilament light chain (NfL) and the body’s response to treatment, reinforcing the NfL’s place as a biomarker for SMA activity and treatment response.

The long-term analysis of the NURTURE study showcases the generally well-tolerated nature of nusinersen, with no new safety concerns arising over eight years. The common adverse events were mostly mild or moderate, without causing any treatment discontinuation or withdrawal.

Biogen is building its legacy in the battle against SMA with its innovation, and is poised to take on the challenges that the disease presents.

About SPINRAZA

SPINRAZA (nusinersen) 12 mg/5 mL injection is approved in more than 71 countries to treat infants, children and adults with spinal muscular atrophy (SMA). More than 14,000 individuals have been treated with SPINRAZA worldwide.¹ The currently approved 12 mg regimen for SPINRAZA is comprised of four loading doses administered over approximately 60 days, followed by maintenance dosing every four months thereafter.

SPINRAZA is an antisense oligonucleotide (ASO) that targets the underlying cause of motor neuron loss by continuously increasing the amount of full-length survival motor neuron (SMN) protein produced in the body.² It is administered directly into the central nervous system, where motor neurons reside, to deliver treatment where the disease starts.² 

SPINRAZA has shown sustained efficacy across ages and SMA types with a well-established safety profile based on data in patients treated up to 10 years,^3,4 combined with unsurpassed real-world experience. The nusinersen clinical development program encompasses more than 10 clinical studies, which have included more than 460 individuals across a broad spectrum of patient populations, including two randomized controlled studies (ENDEAR and CHERISH). The most common adverse events observed in clinical studies were respiratory infection, fever, constipation, headache, vomiting and back pain. Laboratory tests can monitor for renal toxicity and coagulation abnormalities, including acute severe low platelet counts, which have been observed after administration of some ASOs.