FDA Approves High-Dose SPINRAZA After Study Shows 26.19-Point Motor Function Gain
On March 30, 2026, Biogen Inc. secured U.S. Food and Drug Administration (FDA) approval for a new high-dose regimen of its foundational spinal muscular atrophy (SMA) drug, SPINRAZA. The decision allows for a new treatment option consisting of 50 mg loading doses and 28 mg maintenance doses, which will become available in the United States in the coming weeks.
The approval was anchored by data from the pivotal Phase 2/3 DEVOTE study. Results from the study showed that treatment-naïve infants who received the high-dose regimen experienced statistically significant improvements in motor function. They achieved a mean improvement of 15.1 points on the CHOP-INTEND scale, creating a 26.19-point difference when compared to the 11.1-point decline seen in a historical untreated group from the ENDEAR study (p<0.0001).
New Regimen Fortifies Biogen's Market Position with Accelerated Dosing
The high-dose treatment introduces a strategically important accelerated loading phase, with two 50 mg doses administered just 14 days apart. This is followed by a 28 mg maintenance dose every four months. This structure is designed to deliver a higher drug concentration more rapidly, a critical advantage in treating SMA, a degenerative disease where early intervention is crucial to preserving motor neurons.
This approval strengthens Biogen's competitive position in the SMA market, where SPINRAZA has been a cornerstone therapy for over a decade. The high-dose version is already approved in the European Union, Switzerland, and Japan, establishing a broad global footprint. The safety profile of the new regimen was found to be generally consistent with the established low-dose version, with the most common adverse reactions in infants including pneumonia, COVID-19, and malnutrition.
