Salanersen given before symptoms to help movement in babies with genetic SMA

An Open-Label Study to Assess the Efficacy and Safety of Multiple Doses of Salanersen (BIIB115) Delivered Intrathecally to Treatment-Naïve, Presymptomatic Infants With Genetically Diagnosed Spinal Muscular Atrophy

Phase 3 Interventional Biogen · NCT07221669

This study will try salanersen in newborns with genetically confirmed SMA who have 2 or 3 copies of SMN2 to see if starting treatment before symptoms prevents or lessens movement problems.

Quick facts

PhasePhase 3
Study typeInterventional
Enrollment30 (estimated)
Ages0 Days to 42 Days
SexAll
SponsorBiogen Industry-sponsored
Locations2 sites (Flower Mound, Texas and 1 other locations)
Trial IDNCT07221669 on ClinicalTrials.gov

What this trial studies

This Phase 3 interventional trial gives salanersen to presymptomatic infants with genetically diagnosed 5q SMA and either two or three SMN2 copies, starting within the first 42 days of life. Participants must meet electrical and growth criteria and have no clinical signs of SMA at baseline. The study measures clinical motor outcomes, long-term safety, pharmacokinetics, and biomarker changes across two parts including extended follow-up. Outcomes will be compared to natural history benchmarks for presymptomatic SMA to determine whether early treatment changes disease onset or severity.

Who should consider this trial

Good fit: Newborns aged 42 days or younger with genetically confirmed 5q SMA, two or three SMN2 copies, ulnar CMAP ≥2 mV, and no clinical signs of SMA are the intended candidates.

Not a fit: Infants who already show clinical signs of SMA, have areflexia, hypoxemia, or other exclusionary health issues are unlikely to benefit from this presymptomatic approach.

Why it matters

Potential benefit: If successful, early salanersen could prevent or reduce motor weakness and allow infants with SMA to reach more normal developmental milestones.

How similar studies have performed: Other presymptomatic SMN-targeting treatments have produced substantial clinical benefit, supporting the general approach used here.

Eligibility criteria

Show full inclusion / exclusion criteria
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.

Where this trial is running

Flower Mound, Texas and 1 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Muscular Atrophy, Spinal
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.