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Muscular Atrophy, SpinalPhase 3STELLAR-2NCT07444450

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

A Phase 3 study testing Salanersen in people with Muscular Atrophy, Spinal, run by Biogen at 1 site in United States.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
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Trial summary

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 more about this study

Who is it for?
Ages 0 days to 7 months
Conditions the study is for
Muscular Atrophy, Spinal
What is being tested?
Salanersen
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
42 participants
Where
1 siteUnited States
Study dates
31 Oct 2026to 26 Jul 2033
Phase
Phase 3
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 0 days to 7 months
  • All sexes
  • No healthy volunteers
  • Child

Who may be able to join

  • 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 join

  • 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).
  • 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.

Trial locations and contacts

1 site in 1 country. Contact the study team or a site near you to ask about taking part.

US Biogen Clinical Trial Center contact

866-633-4636

clinicaltrials@biogen.com

Global Biogen Clinical Trial Center contact

clinicaltrials@biogen.com

United States1 site, 1 recruiting
  • Neurology Rare Disease Center

    Flower Mound, Texas, 75028

    972-999-1011

    Diana Castro

    Recruiting

Other trials in United States

About this study

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

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.

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.

Read more

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.
Read the detailed description

The primary objective of the study is to evaluate the safety and tolerability of adding salanersen 6 months after OA in participants with genetically diagnosed SMA who received presymptomatic treatment with OA.

The secondary objectives are to evaluate the efficacy and effect on biomarkers of salanersen after OA, and to evaluate the pharmacokinetics (PK) of salanersen in participants with genetically diagnosed SMA who have received presymptomatic treatment with OA.

Being tested
Salanersen, Sham Procedure
Medical subject headings
Muscular Atrophy, Spinal

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • SalanersenDrug

    Also called BIIB115

    Administered intrathecally

  • Sham ProcedureProcedure or surgery

    A sham lumbar puncture is a skin-only needle prick at the usual lumbar puncture site. The needle does not enter the spinal canal.

Study groups in NCT07444450
Study groupRoleWhat they receive
SalanersenExperimentalParticipants 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.
Receives: Drug: Salanersen
Sham ProcedureSham comparatorParticipants 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.
Receives: Drug: Salanersen; Procedure: Sham Procedure

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Parts A: Number of Participants with Adverse Events (AEs) and Serious Adverse Events (SAEs)

    Measured: Part A: Up to Day 365

Secondary outcomes (14)
  1. Part B: Number of Participants with Adverse Events (AEs) and Serious Adverse Events (SAEs)

    Measured: Part B: Up to Day 1825

  2. Parts A and B: Change From Baseline in Plasma Levels of Neurofilament Light Chain (NfL)

    Blood will be collected to characterize changes in plasma NfL following treatment with salanersen. NfL is a protein released from damaged neurons and is a biomarker of neurodegeneration.

    Measured: Part A: At Days 180 and 365; Part B: Up to Day 1825

  3. Parts A and B: Change from Baseline in Compound Muscle Action Potential (CMAP) Amplitudes

    CMAP is a well-validated method for tracking disease progression in neuromuscular disorders such as SMA and amyotrophic lateral sclerosis and has been proposed as a potential biomarker of a therapeutic effect in SMA. CMAPs will be performed for the following nerve-muscle pairs: ulnar-abductor digiti minimi and peroneal-tibialis anterior.

    Measured: Part A: At Day 365 and Part B: Up to Day 1825

  4. Parts A and B: Percentage of Participants Attaining World Health Organization (WHO) Motor Milestones

    The WHO motor milestones will include six key developmental milestones: sitting without support, standing with assistance, hands-and-knees crawling, walking with assistance, standing alone, and walking alone.

    Measured: Part A: At Day 365 and Part B: Up to Day 1825

  5. Parts A and B: Percentage of Participants Attaining Hammersmith Infant Neurological Examination Section 2 (HINE-2) Motor Milestones

    Section 2 of the HINE is used to assess motor milestones and includes 8 motor milestone categories: voluntary grasp (0 to 3), ability to kick in supine position (0 to 4), head control (0 to 2), rolling (0 to 3), sitting (0 to 4), crawling (0 to 4), standing (0 to 3), and walking (0 to 3). Total HINE-2 score is the sum of points from each item and can range from 0 to 26, with higher scores depicting a better level of ability.

    Measured: Part A: At Day 365 and Part B: Up to Day 1825

  6. Parts A and B: Change From Baseline in Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND) Motor Function Scale

    The CHOP INTEND test is designed to evaluate the motor skills of participants with significant motor weakness. It includes 16 items (capturing neck, trunk, and proximal and distal limb strength) structured to move from easiest to hardest with the grading including gravity eliminated (lower scores) to antigravity movements (higher scores). All item scores range from 0-4. The total score ranges from 0-64, with higher scores depicting better motor function.

    Measured: Part A: At Day 365 and Part B: Up to Day 1825

  7. Parts A and B: Percentage of Participants who Remain Free of Clinically Manifested Spinal Muscular Atrophy (SMA)

    Measured: Part A: At Day 365 and Part B: At Day 545

  8. Part B: Percentage of Participants who Develop Spinal Muscular Atrophy (SMA) Subtypes (Non-Sitters, Sitters and Walkers) as Assessed by the Investigator

    Measured: Part B: Up to Day 1825

  9. Part B: Hammersmith Functional Motor Scale Expanded (HFMSE) Total Score

    The HFMSE is a tool used to assess motor function in individuals with SMA. Participants will be asked to complete a specific movement and are then graded on the quality and execution of that movement. Higher scores indicate higher levels of motor ability. The overall score is the sum of the scores for all 33 items, with a maximum score of 66, with higher scores depicting better ability to perform activities.

    Measured: Part B: Up to Day 1825

  10. Part B: Revised Upper Limb Module (RULM) Total Score

    The RULM is developed to assess upper limb functional abilities of participants with SMA. This test consists of a total of 20 upper limb performance items that are reflective of activities of daily living. The RULM is scored from 0 to 37 points, with higher scores indicating better function.

    Measured: Part B: Up to Day 1825

  11. Parts A and B: Time to Death (Overall Survival)

    Measured: Part A: Up to Day 365 and Part B: Up to Day 1825

  12. Parts A and B: Time to Death or Permanent Ventilation

    Permanent ventilation is defined as tracheostomy or ≥16 hours ventilation/day continuously for >21 days in the absence of an acute reversible event.

    Measured: Part A: Up to Day 365 and Part B: Up to Day 1825

  13. Parts A and B: Concentration of Salanersen in Cerebrospinal Fluid (CSF)

    Measured: Part A: Up to Day 365 and Part B: Up to Day 1460

  14. Parts A and B: Concentration of Salanersen in Serum

    Measured: Part A: Up to Day 365 and Part B: Up to Day 1825

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted3 Mar 2026
  2. Study start31 Oct 2026 (estimated)
  3. Primary completion27 Jul 2029 (estimated)
  4. Study completion26 Jul 2033 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 3
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Masking
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
42 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07444450
Sponsor's protocol ID
277SM301
Other IDs
2025-523857-32, 2025
Acronym
STELLAR-2
Status last verified
Oct 2026
First submitted
26 Feb 2026
Last updated
15 Oct 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
Yes: In accordance with Biogen's Clinical Trial Transparency and Data Sharing Policy on https://www.biogentrialtransparency.com/

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing Salanersen in people with Muscular Atrophy, Spinal, run by Biogen at 1 site in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 7 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: looking for participants now, as of the sponsor's last update on 15 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact US Biogen Clinical Trial Center (866-633-4636, clinicaltrials@biogen.com), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Parts A: Number of Participants with Adverse Events (AEs) and Serious Adverse Events (SAEs) (time frame: Part A: Up to Day 365). It is what the study was designed to measure, not a finding.

Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 15 Oct 2026.

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