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Taking peoplePhase 3

Salanersen for babies with spinal muscular atrophy after gene therapy

Tests salanersen in babies with spinal muscular atrophy already treated with onasemnogene abeparvovec.

Key facts

Who runs it
Biogen
Where
Gent, BelgiumSee the siteAlso in 10 other countries, 21 sites
Registry title
A Study to Learn About the Safety and Effects of Salanersen (BIIB115) When Given to Babies With Spinal Muscular Atrophy (SMA) Who Were Previously Treated With Onasemnogene Abeparvovec
Status
Recruiting
Phase
Phase 3
People taking part
42 people, planned
Started
31 Oct 2026
Expected to end
26 Jul 2033
Type of study
Interventional, 2 groupsOne group gets a sham (pretend) treatment, for comparison.
Treatments tested
  • Salanersen
  • Sham Procedure
Record updated
15 October 2026

Who can take part

AI summary

From the trial's eligibility criteria. Machine-read from the registry text on this page, so it can be wrong. The registry text below and the trial team decide who can take part.

The trial is looking for babies with genetically confirmed spinal muscular atrophy (SMA) who had onasemnogene abeparvovec (OA) before showing any symptoms. They must have 2 copies of the SMN2 gene.

Age
From 0 days to 7 months old.
Sex
Boys and girls can both join.
Disease stage
Genetically confirmed 5q SMA with 2 copies of the SMN2 gene. OA was given while the baby had no symptoms of SMA.
Earlier treatment
OA must have been given at 42 days of age or younger, and screening must start less than 6 months after the OA dose. No other SMA treatment may have been given.
Biomarker or test result
Genetic proof of 5q SMA (gene deletion or mutation) and 2 copies of the SMN2 gene.

Main reasons for not taking part

  • Liver test results (ALT or AST) of 2 times the upper limit of normal or more after OA that have not settled
  • Low platelet count compared with the laboratory normal range
  • Troponin-I level that rose after OA and has not returned to normal
  • Corrected QT interval above 450 ms on a heart test
  • Other SMA treatment given besides OA, such as nusinersen or risdiplam, a myostatin inhibitor, or an investigational SMA drug

The registry criteria, word for word

Show all 8 criteriaShow less

Who can take part

  • Genetic documentation of 5q spinal muscular atrophy (SMA) homozygous gene deletion or mutation or compound heterozygous mutation
  • 2 copies of the survival motor neuron 2 (SMN2) gene
  • Onasemnogene Abeparvovec (OA) dose given at ≤ 42 days of age and screening initiated less than 6 months from OA dosing
  • OA dose given while participant was presymptomatic, per Investigator attestation. For this study, presymptomatic is defined as follows:; No clinical signs or symptoms at the time of OA dosing that are, in the opinion of the Investigator, strongly suggestive of SMA; No absence of tendon reflexes (i.e., absence of all of biceps, knee and ankle tendons) at the time of OA dosing (e.g., Hammersmith Infant Neurological Examination (HINE) Section 1 or equivalent); If Compound Muscle Action Potential (CMAP) data is available at the time of dosing, ulnar CMAP amplitude ≥ 2 millivolt (mV)

Who cannot take part

  • Other than OA, any prior treatment with an approved SMA disease modifying therapy (e.g. nusinersen and/or risdiplam), a myostatin inhibitor therapy, or an investigational drug given for the treatment of SMA
  • Steroid treatment administered for the purpose of treating complications following OA within 14 days prior to dosing with salanersen or sham procedure on Day 1; Note: Other protocol-defined inclusion/exclusion criteria will apply
  • Any unresolved post-OA laboratory abnormalities defined as follows:; Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) must be less than 2 × Upper Limit of Normal (ULN) while not receiving corticosteroids within 30 days prior to dosing with salanersen or sham procedure (repeat testing may be performed if necessary); Evidence of thrombocytopenia, indicated by the platelet count being lower than the normal range for the laboratory; Evidence of elevated troponin-I levels, identified as elevated post-OA, and has not returned to the normal range
  • Confirmed demonstration of corrected QT interval, using Fridericia's correction method, of > 450 milliseconds (ms)

Where in Belgium

Also in 10 other countries, 21 sites

  • Universitair Ziekenhuis GentGent, BelgiumNot yet recruiting

About the trial

What the trial wants to find out

In this study, researchers will learn more about the safety and effects of BIIB115, also known as salanersen. Specifically, researchers will learn more about how salanersen works in babies who have already been treated with onasemnogene abeparvovec (OA) after being diagnosed with SMA.

Read full original descriptionShow less

Most people with SMA have changes in a gene called survival motor neuron 1, also known as SMN1. These changes lower the amount of SMN protein in their bodies. Without enough of this protein, motor neurons and muscles cannot work properly. A similar gene called SMN2 can help replace some of the lost SMN protein in the body. Salanersen works by helping the SMN2 gene to make more SMN protein.

OA works by replacing the missing or abnormal SMN1 gene. Sometimes, OA treatment may not work as well as expected. As a result, researchers are exploring whether giving another drug after OA could lead to better outcomes for people with SMA.

In this study, participants will have 2 SMN2 copies. The higher the copy number, the less severe the participant's SMA is. They will also have received treatment with OA by the time they were 42 days old and before showing any symptoms of SMA.

The main goal of the study is to learn more about the safety of giving salanersen to babies after OA treatment. Researchers will also learn more about whether salanersen can help make SMA symptoms less serious.

The main question researchers want to answer in this study is:

• How many participants have adverse events and serious adverse events after treatment?

Researchers will also learn more about:

* The effects on participants' motor symptoms and how many new movement milestones participants achieve. * How many participants stay free of SMA symptoms. * How much neurofilament protein is found in the blood after treatment. * How much salanersen gets into the fluid surrounding the brain and spinal cord. * How much salanersen gets into the blood. Researchers will use different tests to learn if motor symptoms are changing, including the World Health Organization (WHO) motor milestones and Hammersmith Infant Neurological Examination (HINE) Section 2 motor milestones.

The study will be done in 2 parts. Part A will last 1 year while Part B will last up to 4 years.

The study will be done as follows:

* First, participants will be screened to check if they can join the study. The screening period will be up to 6 months. Participants must have received OA treatment before the age of 42 days and started screening within 6 months of the OA dose. * Participants will be assigned to 1 of 2 treatment groups by chance. This is a "double blind" study which means neither the participants, study doctor, nor site staff will know which treatment group the participants are assigned to. * In this study, salanersen will be given as an intrathecal injection, which is an injection into the fluid surrounding the spine. This is done by a procedure called a lumbar puncture (LP) which involves inserting a needle into the lower back into the space around the spinal cord. * During Part A, one group will receive 80 milligrams (mg) of salanersen while another group receives a sham (fake) procedure. This means that a small needle prick will be done, but no injection will be given. * For each participant, the first visit of Part A will be 6 months after they receive OA treatment. * Part A will have up to 6 clinic visits and 2 phone calls and last up to 1 year. * During Part B, both groups of participants will receive 80 mg of salanersen once a year. * Part B will have up to 12 clinic visits and 14 phone calls and last up to 4 years. * In total, participants will be in the study for up to 5 and a half years.

The 2 groups in the trial

  • SalanersenTreatment being tested

    Participants will receive a single dose of salanersen, 80 milligrams (mg) administered intrathecally on Day 1 in Part A. In Part B, participants will continue to receive four additional intrathecal doses of salanersen, 80 mg administered on Days 365, 730, 1095, and 1460.

  • Sham ProcedureSham treatment, for comparison

    Participants will undergo a sham procedure on Day 1 in Part A. In Part B, participants will receive four intrathecal doses of salanersen, 80 mg administered on Days 365, 730, 1095, and 1460.

    Treatment: Salanersen and Sham Procedure

Questions to ask the study team

  1. How often do I need to come in, and for how long each time?
  2. Are travel costs paid?
  3. Can I keep my own doctor?
  4. What happens if I want to stop?

Contact the study team: see the registry record → Contacts and Locations

Print a page for my doctor

Data and sources

Registry record
Listed on ClinicalTrials.gov and on the EU's official list of trials (CTIS).
Official title
A Phase 3, Randomized, Double-Blinded Study to Evaluate the Safety and Efficacy of Salanersen (BIIB115) After Onasemnogene Abeparvovec Treatment in Infants With Genetically Diagnosed Spinal Muscular Atrophy
Plain-language title
Salanersen for babies with spinal muscular atrophy after gene therapyGenerated from the registry record. The registry title is the official one.
AI summary
From the trial's eligibility criteria. Read by machine on 12 November 2026.
Record updated
15 October 2026