Biogen’s High-Dose Nusinersen Secures Positive CHMP Opinion, Opening Door to New SMA Treatment Paradigm
Biogen is on the brink of expanding treatment options for spinal muscular atrophy (SMA) after securing a positive CHMP opinion for its high-dose regimen of nusinersen, the first approved therapy for the disease and long marketed as SPINRAZA®. The endorsement, delivered by consensus from the EMA’s Committee for Medicinal Products for Human Use, sets the stage for a potential European Commission approval in January 2026 a move that could reshape standards of care across a broad SMA population.
For a condition as devastating and heterogeneous as SMA, dose optimization has been a persistent clinical conversation. Nusinersen’s current 12 mg regimen remains foundational across more than 71 countries, with more than 14,000 patients treated worldwide. Yet, as competing modalities including gene therapies and oral agents have captured attention, Biogen has been increasingly focused on strengthening SPINRAZA’s long-term relevance. The high-dose regimen, supported by robust data from the Phase 2/3 DEVOTE study, is the company’s most decisive step in that direction.
What You Need To Know
- CHMP has issued a positive opinion for Biogen’s high-dose nusinersen regimen, with EU approval expected in January 2026.
- DEVOTE study demonstrated significant motor-function gains (+15.1 vs –11.1) and a 68% reduction in death or permanent ventilation.
- Transition patients also benefited, showing improved motor function despite long-term prior treatment.
- The regimen strengthens SPINRAZA’s competitive position amid rising pressure from gene therapies and oral SMA treatments.
A Data-Driven Case for Higher Dosing
The CHMP’s positive opinion is grounded in a comprehensive review of DEVOTE, a global study designed to assess the safety, pharmacokinetics, and efficacy of a higher nusinersen dose in both treatment-naïve patients and those transitioning from the existing 12 mg regimen. The high-dose protocol consists of two 50 mg loading doses administered 14 days apart, followed by 28 mg maintenance doses every four months. Patients transitioning from the 12 mg dose receive a single 50 mg loading dose, then enter the 28 mg maintenance schedule.
In Part B, the pivotal cohort of 75 treatment-naïve infants with symptomatic SMA demonstrated a statistically significant motor-function improvement based on CHOP-INTEND scores. Infants receiving the high-dose regimen showed a +15.1-point mean increase, starkly contrasting the –11.1-point decline observed in a prespecified, matched sham group from the ENDEAR study yielding a dramatic 26.19-point difference (p<0.0001). Mortality and permanent ventilation risk fell by 68% compared to the sham arm.
For clinicians and families navigating the aggressive progression of infantile-onset SMA, these gains represent a meaningful shift: not merely stabilization, but improved developmental trajectories in a population where time is profoundly consequential.
In Part C, which followed previously treated SPINRAZA patients transitioning to the higher dose after a median of nearly four years on the standard regimen, results were similarly encouraging. Participants demonstrated improvements in motor function as measured by the Hammersmith Functional Motor Scale Expanded with an average 1.8-point increase over 302 days. While numerically modest, this improvement is clinically relevant given the typical plateau or decline in long-treated SMA patients.
Safety data remained aligned with expectations. Adverse events, including pneumonia and aspiration pneumonia, reflected known SMA comorbidities, and no new safety concerns emerged in the long-term extension. These findings further reinforce the potential for dose escalation to fortify motor gains without compromising tolerability.
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Biogen’s move arrives at a time when SMA treatment dynamics are evolving rapidly. Gene therapies such as onasemnogene abeparvovec and oral drugs like risdiplam have introduced robust competition, particularly for newly diagnosed infants. Yet SPINRAZA has retained a strong foothold due to its long-term data set and applicability across all SMA types, from infants to adults.
By adding a high-dose regimen, Biogen positions SPINRAZA as not just a legacy therapy, but an adaptable, clinically responsive platform capable of delivering incremental benefits a key consideration for families and neurologists evaluating long-term treatment durability.
Japan has already approved the high-dose regimen, and the U.S. FDA is reviewing Biogen’s submission, with a decision expected by April 3, 2026. With European approval likely just weeks away, Biogen is mobilizing global regulatory engagement to ensure the new dosing option can reach patients quickly.
