NCT07221669 · Biogen
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)
(STELLAR-1)
What this study is about
In this study, researchers will learn more about the effects and safety of BIIB115, also known as salanersen. Specifically, researchers will learn more about how salanersen works in babies who have been diagnosed with SMA through genetic testing but have not yet started showing signs or symptoms. 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 effects and safety of BIIB115, also known as salanersen. Specifically, researchers will learn more about how salanersen works in babies who have been diagnosed with SMA through genetic testing but have not yet started showing signs or symptoms. 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. In this study, participants will have either 2 SMN2 copies or 3 SMN2 copies. The higher the copy number, the less severe the participant's SMA is. The main goal of this study is to see if starting salanersen before signs or symptoms appear can prevent signs or symptoms of SMA or make them less severe. Researchers will use different tests to learn if motor symptoms are changing, including the World Health Organization (WHO) motor milestones. The main questions researchers want to answer in this study are: * How many participants with 2 copies of the SMN2 gene can sit without support at 12 months? * How many participants with 3 copies of the SMN2 gene can walk alone at 18 months? 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 salanersen gets into the fluid surrounding the brain and spinal cord. * How much salanersen gets into the blood. * How many participants have adverse events or serious adverse events. Adverse events are health problems that may or may not be caused by the study drug. This 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 28 days. * This is an "open label" study. This is a study in which the participants, study doctor, and site staff know which study drug participants are receiving. In this study, all participants will receive salanersen through an intrathecal injection, or one that is given into the fluid surrounding the brain and spinal cord. * There will be 2 parts in this study. During Part 1, participants will receive 2 doses of salanersen, about 12 months apart from each other. Part 1 will last up to 25 months. * During Part 2, participants will continue to receive salanersen. They will receive up to 3 doses, 12 months apart from each other. Part 2 will last up to 36 months. * During Part 1, participants will have up to 11 clinic visits and up to 3 phone calls. During Part 2, participants will have up to 7 clinic visits and up to 12 phone calls.
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
- -≤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
- Chicago, Illinois
- Flower Mound, Texas
- Norfolk, Virginia
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.
Is it safe to participate?
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.
Will I be compensated?
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 Jul 6, 2026 · Source of record for eligibility and locations