NCT07444450 · Biogen
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
(STELLAR-2)
What this study is about
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.
View original scientific description
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. 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.
Interventions
DRUG
Salanersen
Administered intrathecally
PROCEDURE
Sham Procedure
A sham lumbar puncture is a skin-only needle prick at the usual lumbar puncture site. The needle does not enter the spinal canal.
Primary outcome measures
Parts A: Number of Participants with Adverse Events (AEs) and Serious Adverse Events (SAEs)
Time frame: Part A: Up to Day 365
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- 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). Key
Exclusion criteria
- 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.
Where
- Flower Mound, Texas
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
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Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
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Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Aug 11, 2026 · Source of record for eligibility and locations