FDA Approves Higher-Dose Regimen of Nusinersen for Spinal Muscular Atrophy

The FDA has approved a new, higher-dose regimen of nusinersen (Spinraza; Biogen) for the treatment of spinal muscular atrophy (SMA), expanding dosing options for patients living with the rare neuromuscular disease.¹

Clinical Data Support Higher Exposure

The FDA’s decision was supported by clinical trial data demonstrating that higher doses of nusinersen led to increased concentrations of the drug in cerebrospinal fluid, which is associated with enhanced pharmacologic activity.^2,3

Findings from the DEVOTE study (NCT04089566), a phase 3 clinical trial evaluating the higher-dose regimen, showed favorable trends in motor function outcomes compared with the standard dosing schedule. Patients receiving the higher dose experienced improvements in motor milestones and functional measures compared with matched placebo participants, as determined by the difference in Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) score (difference, 26.19; 95% CI, 20.7-31.74), supporting the rationale for increased exposure.^2,3

Safety findings were generally consistent with the established safety profile of low-dose nusinersen, with no new safety signals identified. Common adverse events remained similar to those observed with the standard regimen, including procedural complications related to intrathecal administration.^2,3

Updated Dosing Strategy Aims to Enhance Efficacy

SMA is a genetic neuromuscular disorder characterized by degeneration of motor neurons, leading to progressive muscle weakness and atrophy. The disease is caused by mutations in the survival motor neuron 1 (SMN1) gene, resulting in insufficient production of functional SMN protein.²

Nusinersen, an antisense oligonucleotide therapy, works by modifying splicing of the SMN2 gene to increase production of functional SMN protein. The newly approved regimen increases the maintenance dose compared with the original schedule, with the goal of achieving higher drug exposure in the central nervous system.^1,2

According to the manufacturer, the updated regimen includes higher maintenance dosing following the initial loading phase, which may allow for improved and sustained therapeutic benefit over time.¹

Expanding Treatment Options in a Competitive Landscape

The approval of a higher-dose regimen comes as the SMA treatment landscape continues to evolve. Nusinersen was the first FDA-approved therapy for SMA in 2016 and has since been widely used across pediatric and adult populations.²

Additional therapies—including gene replacement therapy and oral splicing modifiers—have expanded treatment options in recent years, offering different routes of administration and mechanisms of action. Despite this, nusinersen remains a foundational therapy, particularly for patients who may not be eligible for or prefer alternatives.²

Experts note that optimizing dosing strategies may help maintain the clinical relevance of nusinersen amid increasing competition, particularly by improving outcomes without requiring a switch in therapy.³

Implications for Pharmacists and Patient Management

For pharmacists, the new dosing regimen introduces considerations related to administration, monitoring, and patient counseling. Nusinersen is administered via intrathecal injection, often requiring coordination with specialized care teams and imaging guidance in certain patients.²

The higher-dose regimen may also impact treatment scheduling and resource utilization, particularly in infusion centers and specialty clinics. Pharmacists will play a key role in ensuring appropriate dosing, managing adverse events, and supporting adherence to the revised regimen.

Additionally, the approval underscores the importance of individualized treatment decisions in SMA, where factors such as disease severity, age at treatment initiation, and patient preference may influence therapy selection.²

Ongoing Research and Long-Term Outcomes

Although the approval is supported by pharmacokinetic and clinical data, ongoing studies are expected to further evaluate the long-term benefits of higher-dose nusinersen.³ These investigations will be critical in determining whether increased drug exposure translates into sustained functional improvements and disease stabilization.

As treatment options for SMA continue to expand, the availability of a higher-dose nusinersen regimen provides clinicians with additional flexibility in optimizing care for patients with this complex, progressive disease.

REFERENCES

1. FDA approves new high-dose regimen of Spinraza (nusinersen) for spinal muscular atrophy. News release. Biogen. March 30, 2026. Accessed April 1, 2026. https://investors.biogen.com/news-releases/news-release-details/fda-approves-new-high-dose-regimen-spinrazar-nusinersen-spinal

2. Finkel RS, Crawford TO, Mercuri E, et al. High-dose nusinersen for spinal muscular atrophy: a phase 3 randomized trial. Nat Med. 2026;32(3):1095-1104. doi:10.1038/s41591-025-04193-6

3. Spinal muscular atrophy. National Institute of Neurological Disorders and Stroke. Accessed April 1, 2026. https://www.ninds.nih.gov/health-information/disorders/spinal-muscular-atrophy