Biogen Inc. has announced that the U.S. Food and Drug Administration has approved a high-dose regimen of its therapy SPINRAZA for the treatment of spinal muscular atrophy (SMA), marking a significant advancement in treatment options for patients living with the rare disease.
The newly approved regimen introduces higher dosing levels—50 mg/5 mL and 28 mg/5 mL—compared to the long-standing 12 mg low-dose version. Backed by over a decade of clinical experience with the original dosing, the high-dose formulation is designed to deliver a greater concentration of the drug during both the initial loading and ongoing maintenance phases, potentially enhancing therapeutic outcomes.
The updated dosing schedule allows newly treated patients to undergo an accelerated loading phase, beginning with two 50 mg doses administered 14 days apart. This is followed by maintenance doses of 28 mg every four months. Patients already receiving the low-dose regimen can transition by completing a single high-dose loading phase before continuing with the regular four-month maintenance interval.
The FDA’s decision is supported by data from the Phase 2/3 DEVOTE clinical trial. In the pivotal cohort, symptomatic infants who had not previously received treatment demonstrated statistically significant improvements in motor function. These gains were measured using the CHOP-INTEND scale and compared to a matched untreated group from the ENDEAR study, showing a notable mean improvement difference of 26.19 points.
Experts in the field have welcomed the approval, noting the potential impact on patient outcomes. The higher dose maintained a safety profile consistent with the established low-dose regimen. However, some adverse events were reported more frequently, including pneumonia, COVID-19, aspiration pneumonia, and malnutrition, particularly in infants with early-onset SMA.
Biogen emphasized that the development of the high-dose regimen reflects its continued commitment to improving care for the SMA community. Patient advocacy groups have also acknowledged the milestone, highlighting the importance of expanding treatment options nearly a decade after Spinraza first transformed the SMA treatment landscape.
The high-dose version of Spinraza has already received approvals in regions including the European Union, Switzerland, and Japan. Biogen is continuing to work with global regulators to expand access to the therapy worldwide.