A Study to Learn About Salanersen's (BIIB115) Effects on Movement and Its Safety When Given Before Symptoms Appear in Babies With Genetically Diagnosed Spinal Muscular Atrophy (SMA)

Plain-language summary

This study looks at the effects on movement and the safety of the drug Salanersen (BIIB115) when given before symptoms appear in babies with genetically diagnosed spinal muscular atrophy (SMA). Babies with a 5q SMA genetic diagnosis, two or three copies of the SMN2 gene, and aged 42 days or younger at first dose may take part. The study is in Phase 3 and is currently recruiting participants.

The summary above is a plain-language rendering of the official record. The original English title is shown for reference.

Trial details

Phase

Phase 3

Status

Recruiting

Sponsor

Biogen

Intervention

Salanersen

Start date

4/28/2026

Estimated completion

5/29/2032

Countries

United States, China, Japan

Related genes

Locations

• Chicago, United States
• Flower Mound, United States
• Norfolk, United States
• Shanghai, China
• Tokyo, Japan

Eligibility criteria

Criteria are reproduced from the ClinicalTrials.gov record in the original English. Only the trial team can determine eligibility.

Key Inclusion Criteria:

-≤42 days of age at first dose of salanersen.

* Genetic documentation of 5q SMA homozygous gene deletion or mutation or compound heterozygous mutation.
* Two or three copies of the survival motor neuron 2 (SMN2) gene.
* Ulnar compound muscle action potential (CMAP) amplitude ≥2 millivolt (mV) at Screening and Day 1 predose.
* Body weight ≥3rd percentile for age based on World Health Organization (WHO) Child Growth Standards at the time of informed consent.

Key Exclusion Criteria:

* Any clinical signs or symptoms at Screening or Day 1 predose that are, in the opinion of the Investigator, strongly suggestive of SMA.
* Areflexia on neurologic examination at biceps, knee, or ankle at Screening or Day 1 Predose.
* Hypoxemia (oxygen saturation \<96% awake or asleep without any supplemental oxygen or respiratory support, or for altitudes \>1000 meters (m), oxygen saturation of \<92% awake or asleep without any supplemental oxygen or respiratory support).
* Diagnosis of neonatal respiratory distress syndrome necessitating surfactant replacement therapy or invasive ventilatory support.
* Any reason, anatomical or otherwise (including hematology/coagulation laboratory results), that presents increased risk of complication from the LP procedures or safety assessments.
* Any prior treatment with an approved SMA disease-modifying therapy (e.g., nusinersen, onasemnogene abeparvovec-xioi \[OA\], and/or risdiplam), a myostatin inhibitor therapy, or an investigational drug given for the treatment of SMA.

Note: Other protocol-defined inclusion/exclusion criteria will apply.