Biogen's salanersen enters Phase 3 as first patients are dosed

Biogen announced on September 22, 2026, that its Phase 3 studies of salanersen are now enrolling — from infants to adults — and the first participants have already been dosed in the U.S. and Japan. Salanersen is an investigational antisense oligonucleotide (ASO) in the same class as Spinraza (nusinersen), but it is designed to be given intrathecally just once a year instead of every four months.

The program includes three studies, all using an 80 mg once-yearly dose: STELLAR-1 — infants younger than 6 weeks diagnosed before symptoms appear; STELLAR-2 — infants who received Zolgensma gene therapy, with salanersen started about 6 months later (a randomized, controlled study); SOLAR — teens and adults aged 15–60 who are untreated or previously treated with Evrysdi (risdiplam).

In June, the FDA granted salanersen Breakthrough Therapy Designation — we covered it here. Phase 3 results are expected in the coming years.

Source: Cure SMA, ClinicalTrials.gov.