Biogen Shows 75% NfL Reduction and New Motor Milestones with Salanersen
Biogen’s Phase 1b study of salanersen in 24 children with spinal muscular atrophy previously treated with gene therapy showed 75% reductions in neurofilament light chain levels at six months and sustained improvements over one year. Half of participants achieved a new WHO motor milestone and all maintained function.
1. Phase 1b Safety and Dosing
The Phase 1b trial enrolled 24 children aged six months to 12 years previously treated with onasemnogene, evaluating salanersen at 40 mg and 80 mg once-yearly doses. Both dose levels were generally well tolerated over one year, with most adverse events mild to moderate, including upper respiratory infections and transient fever.
2. Biomarker and Motor Improvements
Participants with elevated baseline neurofilament light chain levels experienced 75% reductions by six months, sustained throughout follow-up. All 24 children showed functional gains, with 12 achieving at least one new WHO motor milestone and all maintaining their baseline motor abilities.
3. Global Phase 3 Program Launch
Biogen has initiated the STELLAR-1 open-label study in presymptomatic infants under six weeks old, with SOLAR teens and adults launching in Q2 2026 and STELLAR-2 randomized trial planned for Q3 2026. These studies will evaluate once-yearly 80 mg dosing across treatment-naïve and previously treated populations.