AuthorisedTherapeutic confirmatory (Phase III)Interventional

An 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

Spinal muscular atrophy (SMA) is a genetic condition that causes muscles to become weak and waste away over time. This phase 3 clinical trial is testing a new study medicine called salanersen (also known as BIIB115) in people living with SMA. Researchers are looking to see how safe and effective the medicine is. They want to find out if it can help improve everyday movement, upper body and arm strength, and walking endurance. The study includes people who have never had drug treatment for SMA, as well as those who have taken a medicine called risdiplam in the past. Because this is an 'open-label' study, all participants will receive the active study medicine. Taking part involves regular health checks and simple physical tests over several years to monitor how your body responds to the treatment.

At a glance

Status

Authorised

Phase

Therapeutic confirmatory (Phase III)

Sponsor

Biogen Idec Research Limited

Enrolment target

Start

24 Jul 2026

Spinal Muscular Atrophy

What is this study about?

Spinal muscular atrophy (SMA) is a rare, inherited condition that affects the nerves responsible for controlling muscle movement. Over time, these nerves become damaged, which leads to muscle weakness. This can make everyday activities, such as sitting up, moving your arms, or walking, much harder. While new treatments have been developed in recent years, scientists are still searching for new medicines that can better preserve or improve strength for people living with SMA.

This study is testing an investigational drug called salanersen (BIIB115). It is a Phase 3 trial, which means earlier studies have already shown initial promise, and researchers now need to test it in a larger group of people to confirm how well it works and track any side effects. The study is open-label, meaning everyone who takes part will receive the actual study medicine rather than a dummy drug (placebo).

During the trial, the research team will track changes in participants' muscle strength and mobility. By carefully measuring how well people can perform everyday physical tasks, doctors hope to learn whether salanersen could become an effective long-term treatment option for individuals with SMA, whether they are new to treatment or have previously tried other medications like risdiplam.

Key takeaways

Tests an experimental drug called salanersen (BIIB115) for spinal muscular atrophy (SMA).
Open to people aged 15 to 60 who are either new to treatment or have had risdiplam before.
This is an open-label trial, so all participants receive the study medicine without a placebo.
Involves physical movement, arm function, and walking assessments over several years.
Participation is voluntary, and you can withdraw at any time without affecting your NHS care.

Who may be eligible?

This study is designed for teenagers and adults living with spinal muscular atrophy (SMA). The study title indicates researchers are looking for participants between the ages of 15 and 60, although adults aged 18 and older are eligible under standard site recruitment criteria. Both men and women can participate.

To be considered, you may be someone who has never received drug treatment for your SMA before (treatment-naïve). You might also be eligible if you have previously been treated with a medication called risdiplam and meet specific criteria to switch or take part.

Not everyone will be suitable for the study. Factors such as your overall health, other medical conditions, and previous therapies will be carefully reviewed by the study doctors to make sure joining the trial is safe and appropriate for you.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

I have a confirmed diagnosis of spinal muscular atrophy (SMA).
I am between 15 and 60 years old.
I have either never received medical treatment for SMA, or I was previously treated with risdiplam.
I am able and willing to attend regular hospital appointments for check-ups and mobility tests.
I am interested in taking part in a long-term clinical trial.

Answer every question to see your result.

What does participation involve?

If you decide to take part, you will receive the study medicine, salanersen, and be monitored regularly by a specialist hospital team. Because this is a long-term study, participation may last for up to five years (around 1,825 days).

During your visits, the research team will check your overall health and measure your muscle function. These assessments are gentle and practical. They include the Hammersmith Functional Motor Scale, where you perform everyday movements to see how well your muscles respond. You will also do an upper limb test that looks at arm and hand coordination, such as lifting or reaching. If you are able to walk, you may be asked to do a six-minute walking test to measure your stamina.

Your study team will guide you through all hospital appointments, arrange regular health checks, and monitor your progress closely throughout the entire study period.

Potential risks and benefits

Taking part may give you access to a new SMA treatment and close medical care from specialists. The medicine could help stabilize or improve your movement and strength, though these benefits cannot be guaranteed. As with any new medicine, there are risks of side effects, and you will need to attend regular clinic visits for testing. Your safety is the priority, and the study team will monitor you closely. Participation is entirely voluntary, and you are free to leave the study at any time without affecting your normal NHS care.

Locations (7)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

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Unverified
Finland
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Unverified
Spain
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Unverified
Italy
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Unverified
Poland
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Unverified
Ireland
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Unverified
Germany
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Unverified
France

Common questions

What is an open-label study?

An open-label study means that both you and the study doctors know which treatment you are receiving. There is no placebo (dummy treatment) used in this trial.

What is salanersen (BIIB115)?

Salanersen is an experimental medicine being developed to treat spinal muscular atrophy by helping to support and protect the nerve cells that control muscle movement.

Will taking part cost me anything?

No, the study medicine and all trial-related tests are provided free of charge. Most clinical trials also help cover travel expenses to and from hospital visits.

What happens if my condition gets worse during the study?

Your health and safety come first. If your condition changes or you experience troubling side effects, the study doctor will discuss all options with you, including stopping the trial.

Can I leave the study early if I change my mind?

Yes. Taking part is completely voluntary. You can choose to withdraw from the trial at any point, and your standard medical care will not be affected.