A Study to Learn About Salanersen's (BIIB115) Effects on Movement and Its Safety in Participants Aged 15 to 60 Years With Spinal Muscular Atrophy (SMA) Who Are Either New to SMA Treatment or Were Previously Treated With Risdiplam

Recruitment Status
RECRUITING
(See Contacts and Locations)Verified March 2026 by Biogen
Sponsor
Biogen
Information Provided by (Responsible Party)
Biogen
Clinicaltrials.gov Identifier
NCT07444476
Other Study ID Numbers:
277SM303
First Submitted
February 25, 2026
First Posted
March 2, 2026
Last Update Posted
April 20, 2026
Last Verified
March 2026

ClinicalTrials.gov processed this data on April 2026. Link to the current ClinicalTrials.gov record .

History of Changes

Study Details

Study Description

The primary objective of the SOLAR study is to evaluate the clinical efficacy of salanersen in participants with SMA who are treatment-naïve or previously treated with risdiplam. The secondary objective of the study is to evaluate the safety, tolerability, and pharmacokinetics (PK) of salanersen.

Condition or DiseaseIntervention/Treatment
Spinal Muscular Atrophy
Drug: SalanersenDrug: Salanersen

Study Design

Study TypeInterventional
Actual Enrollment90 participants
Design AllocationN/A
Interventional ModelParallel Assignment
MaskingNone (Open Label)
Primary PurposeTreatment
Official TitleAn Open-Label, Phase 3 Study to Evaluate the Efficacy and Safety of Salanersen (BIIB115) in Participants Aged 15-60 Years With Spinal Muscular Atrophy Who Are Either Treatment-Naïve or Have Previously Been Treated With Risdiplam
Study Start DateApril 2, 2026
Actual Primary Completion Date1yr 10mos from now
Actual Study Completion Date5yrs 10mos from now

Groups and Cohorts

Group/CohortIntervention/Treatment
Treatment-Naïve Cohort
Treatment-naïve participants will receive salanersen 80 milligrams (mg) by intrathecal (IT) lumbar puncture (LP) every 12 months for a total of five doses.
Drug: Salanersen
Administered Intrathecally
Risdiplam-Treated Cohort
Risdiplam-treated participants will receive salanersen 80 mg by IT LP every 12 months for a total of five doses.
Drug: Salanersen
Administered Intrathecally

Outcome Measures

Primary Outcome Measures
  1. Change From Baseline in Hammersmith Functional Motor Scale - Expanded (HFMSE) Total Score in Treatment-Naïve Cohort
    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.
Secondary Outcome Measures
  1. Percentage of Participants With ≥ 3-Point Change From Baseline in 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.
  2. Percentage of Participants With ≥ 2-Point Change From Baseline in 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.
  3. Percentage of Participants With ≥ 30-Meter Change From Baseline in 6-Minute Walk Test (6MWT) Distance (Ambulatory Participants Only)
    The 6MWT is a submaximal exercise test used to assess an individual's functional exercise capacity. It measures the distance covered in 6 minutes on a flat, hard surface, providing valuable information about aerobic capacity and endurance.
  4. Change From Baseline in 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.
  5. Change From Baseline in 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.
  6. Change From Baseline in Total 6MWT Distance (Ambulatory Participants Only)
    The 6MWT is a submaximal exercise test used to assess an individual's functional exercise capacity. It measures the distance covered in 6 minutes on a flat, hard surface, providing valuable information about aerobic capacity and endurance.
  7. 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.
  8. Patient Global Impression of Change (PGI-C) Score
    PGI-C is a self-reported 7-point scale evaluating the participant's perception of change in disease state since baseline. The scale ranges from 1 to 7, where 1= very much improved; 2= much improved; 3= minimally improved; 4= no change; 5= minimally worse; 6= much worse; or 7= very much worse. Lower scores indicate clinical improvement, and higher scores indicate disease worsening.
  9. Change From Baseline in SMA Independence Scale - Upper Limb Module (SMAIS-ULM)
    The SMAIS-ULM is a validated tool designed to assess the level of independence in daily activities related to upper limb functionality for individuals with Type II and nonambulant Type III SMA. The 22 items assess upper limb focused tasks across 5 domains of typical daily activities (bathing/hygiene, dressing, eating/drinking, picking up/moving objects, and other tasks) scored on a 3-point scale (0 = I cannot do this at all without help; 1 = I need some help; and 2 = I do not need help). Higher scores indicate greater independence.
  10. Number of Participants with Adverse Events (AEs) and Serious Adverse Events (SAEs)
  11. Concentration of Salanersen in Cerebrospinal Fluid (CSF)
  12. Concentration of Salanersen in Serum

Eligibility Criteria

Ages Eligible for Study(Child, Adult)
Sexes Eligible for StudyAll
Accepts Healthy VolunteersNo
Inclusion Criteria
Participants aged 15 to 60 years, inclusive, at the time of informed consent
Participants with genetic documentation of 5q Spinal Muscular Atrophy (SMA) (homozygous gene deletion or mutation or compound heterozygous mutation).
Participants with clinical signs and symptoms consistent with SMA.
Survival motor neuron 2 (SMN2) copy number ≥ 1.
Participants with baseline Hammersmith Functional Motor Scale - Expanded (HFMSE) total score of ≥ 10 to ≤ 54.
Participants who are able to sit without using support for at least 10 seconds.
Participants with no prior treatment with myostatin inhibitors and a willingness to remain off concurrent myostatin inhibitor therapy for the duration of the study.
Ambulatory and nonambulatory participants:
Ambulatory participants must be able to walk at least 10 meters independently without assistance and are willing and able to complete the 6 Minute Walk Test (6MWT) at Screening.
For participants in the treatment-naïve cohort:
No prior treatment with an approved SMA Disease Modifying Therapy (DMT) or an investigational drug given for the treatment of SMA.
For participants in the risdiplam-treated cohort:
Currently receiving risdiplam treatment and have been on once-daily 5 milligrams (mg) risdiplam treatment for at least 6 months prior to Screening.
Willing to stop risdiplam therapy for the duration of the study. The last dose of risdiplam must be taken the day before the first dose of salanersen.
No prior treatment with nusinersen, onasemnogene abeparvovec-xioi/onasemnogene abeparvovec-brve (OA), other approved DMTs for SMA or investigational drugs given for the treatment of SMA apart from risdiplam. Key
Exclusion Criteria
Respiratory insufficiency at Screening, defined by the medical necessity for invasive or noninvasive ventilation for \> 6 hours during a 24-hour period (except for nocturnal bilevel positive airway pressure).
Medical necessity for a gastric feeding tube, where the majority of nutrition is provided by this route, as assessed by the site Investigator at Screening.
History of brain or spinal cord disease or other contraindications (e.g., severe scoliosis) that would interfere with the lumbar puncture (LP) procedures, Cerebrospinal fluid (CSF) circulation, efficacy assessments, or safety assessments (including a history of hydrocephalus or implanted shunt for CSF drainage), as assessed by the Investigator.
Hospitalization for surgery, a pulmonary event, or nutritional support within 2 months prior to Screening or plans to undergo elective procedures or surgeries at any time after signing the Informed Consent Form (ICF) through the end of the study. Note: If prior scoliosis surgery has been performed, it must be done at least 1 year prior to Screening.
Presence of an active medical issue (e.g., infection, recent fracture) that would make the participant unsuitable for inclusion, as assessed by the Investigator.
Current enrollment or a plan to enroll in any interventional clinical study in which an investigational treatment or approved therapy for investigational use is administered within 90 days or 5 half-lives of the treatment (if known), whichever is longer, prior to Screening. This includes neuromodulation therapy such as spinal cord stimulation. Note: Other protocol-defined inclusion/exclusion criteria will apply.

Contacts and Locations

Sponsors and CollaboratorsBiogen
Locations
Childrens Hospital of the Kings Daughter Norfolk | Norfolk Virginia, United States, 23507
Investigators
Study Director: Medical Director, Biogen