The U.S. Food and Drug Administration has approved a higher-dose version of Biogen’s spinal muscular atrophy (SMA) drug Spinraza, marking a new development for the therapy nearly a decade after its initial authorization. The approval follows a prior rejection last year and introduces a revised dosing regimen.
Spinraza initially gained rapid uptake after its first approval, achieving blockbuster sales within two years and remaining a consistent contributor to Biogen’s revenue. Over time, however, competition from Roche’s Evrysdi and Novartis’ Zolgensma has reduced its market share.
The newly approved high-dose version incorporates an accelerated loading schedule. Patients receive two initial 50-milligram doses spaced 14 days apart, followed by maintenance doses of 28 milligrams administered every four months. This differs from the original lower-dose regimen, which requires four loading doses over approximately two months before continuing maintenance treatment.
Clinical data supporting the approval comes from the phase 2/3 Devote study. In the trial, treatment-naive symptomatic infants with SMA who received the higher-dose regimen showed measurable improvements in motor function compared with an untreated control group from a prior study. Specifically, treated patients demonstrated a 15.1-point increase on the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders scale, while untreated patients in the earlier Endear study experienced an 11.1-point decline.
Additional findings from an open-label portion of the study indicated that patients who transitioned from the lower-dose version to the higher-dose regimen also experienced motor function improvements after switching.
Biogen Chief Executive Officer Chris Viehbacher discussed the results during a conference call, stating that the higher-dose formulation achieved stronger outcomes. He said, “much higher levels of efficacy,” which he added suggests that reaching therapeutic levels more quickly may provide increased benefit. He also referenced early use in other countries, noting that the rollout has seen uptake among newly treated patients as well as individuals switching back from competing therapies.
The approval comes as Biogen faces sustained competition in the SMA market. Roche’s Evrysdi, initially approved in 2020 as an oral solution and later as a tablet, has treated more than 21,000 patients, according to company disclosures. Meanwhile, Novartis’ gene therapy Zolgensma continues to generate significant sales despite its distinct treatment approach.
Sales figures from the previous year illustrate the competitive landscape. Spinraza generated $1.55 billion in revenue, compared with approximately $2.11 billion for Evrysdi and $1.23 billion for Zolgensma.
Biogen plans to launch the higher-dose Spinraza in the United States in the coming weeks, while rollout efforts are already underway in certain international markets. The company stated that the 28-milligram vial will be priced at approximately $152,000, consistent with the current 12-milligram dose, while the 50-milligram vial will carry a list price of about $271,000.
According to Jefferies analyst Andrew Tsai, the revised dosing approach may help address diminishing treatment effects observed in some patients and could expand use among adult populations, potentially contributing to growth beginning in 2026.
Biogen’s shares rose 3.3% in morning trading following the announcement.
What the Spinraza Approval Means
The FDA’s decision to approve a higher dose of Spinraza reflects growing clinical evidence supporting improved outcomes with optimized dosing. With this update, Spinraza continues to strengthen its position as a leading therapy for SMA, addressing a broader range of patient needs.
Clinical Benefits of Higher-Dose Spinraza
Clinical studies have shown that the higher-dose regimen of Spinraza can improve motor function and disease stabilization in SMA patients. By increasing drug exposure in the central nervous system, Spinraza enhances its effectiveness in slowing disease progression, making Spinraza an even more valuable treatment option.
How Spinraza Works
Spinraza is an antisense oligonucleotide therapy designed to target the underlying genetic cause of SMA. By increasing SMN protein production, Spinraza helps support motor neuron survival. The higher-dose approach further optimizes how Spinraza performs at a biological level.
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