Today, Biogen announced plans to initiate Phase 3 development to evaluate the effectiveness and safety of salanersen, an investigational drug for the treatment of spinal muscular atrophy (SMA). Phase 3 initiation follows the announcement of positive interim results of the Phase 1 study of salanersen, which informed the design of the studies.
Biogen is preparing for enrollment of the pivotal study (STELLAR-1) which will assess the efficacy and safety of salanersen in treatment-naïve presymptomatic infants with SMA and will begin recruiting in the US by December 2025. Biogen is also planning additional Phase 3 studies to evaluate salanersen in the broader SMA population, including treatment-naïve and previously-treated patients.
For more information or to learn more about this clinical trial, please contact Biogen at [email protected] or call the Biogen Clinical Trials Center at 866-633-4636.
For the full community statement from Biogen, please click here.

