Spinal muscular atrophy guide to clinical trials

Last updated Aug. 6, 2025, by Agata Boxe
✅ Fact-checked by Ana de Barros, PhD

Although researchers have made progress developing therapies for spinal muscular atrophy (SMA), more work is needed to address disease progression and improve strength, mobility, and quality of life.

Scientists continue to explore new treatments through clinical trials, which assess whether new therapies are safe and effective before they are approved by the U.S. Food and Drug Administration (FDA).

Enrolling in an SMA clinical trial may give you or your child access to experimental treatments while helping to advance medical research. However, it is important that you consult your doctor or your loved one’s doctor as part of your decision-making process.

What is an SMA clinical trial?

A clinical trial is a carefully designed research study that tests new ways to treat, diagnose, and manage diseases, such as SMA, in people. While early-stage clinical trials typically follow laboratory and animal testing, later-stage trials build on findings from earlier human studies.

Clinical trials for SMA may focus on:

  • trying to improve muscle strength or motor function through medications
  • studying compounds that may help protect nerve cells from damage or death
  • studying new gene or mRNA-based therapies
  • assessing treatments for respiratory, nutritional, or orthopedic complications
  • testing new strategies to monitor disease progression or treatment response.

 

Clinical trials come in four separate phases:

  • Phase 1 trials test a treatment’s safety and determine appropriate dosages and regimens in a small number of participants.
  • Phase 2 trials continue to monitor safety and begin to evaluate how well the treatment works, often comparing it with a placebo or standard treatment in a larger group of patients.
  • Phase 3 trials are designed to confirm the safety and effectiveness of the new therapy against a placebo or an existing treatment, often involving even larger populations and treatment durations. These trials are usually conducted to support the therapy’s approval by regulatory entities.
  • Phase 4 trials are done after the therapy has received FDA approval to study its long-term effects and benefits in a real-world setting.

Weighing the benefits and risks of SMA trials

While the progressive nature of SMA and its severity may make someone more willing to join a clinical trial, it’s crucial to understand both the potential benefits and the risks.

The benefits of clinical trials include:

  • early access to new treatments
  • a chance to proactively manage your or your loved one’s SMA
  • an opportunity to contribute to research that may benefit others with SMA.

The risks of clinical trials can involve:

  • potential side effects from the new treatment
  • lack of improvement or worsening of symptoms
  • possibility of receiving a placebo or standard treatment
  • extra time for appointments, testing, or travel
  • costs not covered by insurance or the study sponsor.

Types of SMA clinical trials

Clinical trials for SMA can focus on various aspects of SMA care, ranging from testing new interventions that modify the disease course or improve quality of life to identifying new biomarkers that aid in monitoring disease progression and response to treatment.

Not all trials may be available or recruiting participants at any given time, but some examples of SMA trials that may be conducted include:

  • gene therapy or mRNA-based trials aimed at addressing the underlying genetic causes of SMA
  • treatments that aim to slow nerve cell loss
  • therapies that may help to preserve strength and improve mobility
  • trials targeting respiratory, nutritional, or bone problems
  • studies using imaging tests, biomarkers, or digital tools to track progression or response to treatment.

Some SMA trials are tailored to people with specific SMA types as well as different age groups or genetic profiles. They may also be available only to individuals who have never received treatment or who are no longer responding to approved SMA treatments.

Where to find SMA clinical trials

To find an SMA clinical trial, start by talking to your or your child’s SMA doctor, who may know of trials through academic hospitals, research centers, or clinical trial networks. They can also help evaluate whether you or your child may be eligible for a trial.

Additionally, you can consult online resources for more information. Resources that may help you find a suitable SMA trial in the United States include:

SMA trial registries outside the United States include:

What to ask before joining an SMA clinical trial

If you’re considering participating in an SMA clinical trial, asking the right questions can help you make an informed decision. It may be helpful to put together a list of questions for your SMA doctor, the research team, and even yourself as you learn more about the trial process.

Questions for your SMA doctor

Your doctor can answer general questions about SMA trials, such as:

  • Am I a good candidate for an SMA clinical trial?
  • Are you aware of any clinical trials that would be suitable for my disease type and symptoms?
  • Would participating in a trial affect my current treatment plan?
  • What are the potential risks and benefits of the trial you may be recommending?
  • What would the trial require in terms of treatment, travel, and time commitment?

Questions for the research team

The research team running the trial can address more detailed questions about its design and potential side effects.

Examples of questions for the researchers include:

  • What kind of treatment will the trial be testing, and why do you think it will work?
  • Are there any known side effects, and if so, how can they be managed?
  • Does this study involve a placebo or another SMA treatment that is already on the market?
  • What are the odds of receiving a placebo or another SMA treatment versus the new treatment?
  • Who will cover the costs of my participation in the trial, and do I need insurance?

Inquiring about potential costs is especially important. Although most trials tend to cover the costs of experimental treatment and any related medical care, that may not be the case for every single study.

If you are currently insured, ask your insurer whether they can pay for your participation in the study and care for potential side effects.

Questions to ask yourself

Personal reflection can help you decide whether a trial might be right for you. Questions to ask yourself include:

  • How do I hope to benefit from the trial, and are my expectations realistic?
  • Am I willing to accept the risks, such as potential side effects or a chance of receiving a placebo?
  • How may this trial affect my daily life?
  • Am I willing to accept the time commitment and potential travel and expenses related to the trial?
  • Can I manage the emotional impact if the new treatment doesn’t work for me?

Additional information about SMA clinical trials

SMA clinical trials can provide a chance to try experimental treatments and play an active role in your or your child’s SMA care. However, keep in mind that they’re not for everyone, so it’s important to understand their risks and benefits.

Remember to talk to your SMA doctor first, so they can help you decide whether an SMA trial is right for you. Don’t hesitate to ask questions and advocate for yourself as you make this and other key decisions about your health and future.

SMA News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

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AveXis Phase 3 Trial Studying Gene Therapy for SMA Type 1 Now Enrolling Infants

A Phase 3 clinical trial to evaluating the safety and efficacy of an investigational gene replacement therapy by AveXis is now recruiting infants with spinal muscular atrophy type 1. The trial of AVXS-101 is seeking patients younger than six months of age. Participants must have a genetic mutation analysis confirming SMA type 1 diagnosis, according to a news release from the Muscular Dystrophy Association. AVXS-101 is designed to specifically deliver the fully functional human SMN gene to motor neurons, which SMA patients lack. This will restore normal levels of survival motor neuron protein in these nerve cells, allowing them to properly control muscle activity and improve strength and function. Results of a Phase 1 study showed that the motor functions of babies with SMA type 1 show clinically meaningful improvements after one single intravenous infusion. Eight of the 15 infants treated with AVXS-101 were able to sit without assistance and two could crawl, stand or walk independently — all abilities never seen in untreated SMA infants. The U.S. Food and Drug Administration has granted AVXS-101 Orphan Drug Designation to treat all types of SMA. AVXS-101 has also received Breakthrough Therapy Designation and Fast Track Designation to treat SMA Type 1. Both will speed up the drug's clinical development and potential approval. The STR1VE study is an open-label Phase 3 trial to evaluate the impact of AVXS-101 on children’s development and overall survival. It will likely include 15 infants with genetically confirmed non-functional SMN1 gene, but with one or two copies of the SMN2 gene. The study — to be conducted at clinics in California, Colorado, Illinois, Maryland, New York, Ohio and Oregon — will evaluate patients' capacity to sit by themselves at 18 months of age, as well as their ability to breathe without additional support upon receiving one injection of AVXS-101. All required clinical visits, tests and additional treatments will be provided to participants at no cost, as well as travel assistance for families who don't live near any of the study sites. For additional information on the STR1VE trial, please visit the study website or the study registry page. To participate, contact the trial coordinator at the nearest site.

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Early Spinraza Treatment for SMA Leads to Improved Motor Function, Biogen Says

Spinraza (nusinersen) may provide more benefits to infants with spinal muscular atrophy (SMA) if the treatment is started early, Biogen reported during presentations at the ongoing 22nd International Congress of the World Muscle Society in St. Malo, France. But the treatment can also provide benefits to SMA patients…

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FDA Approves AveXis’ Pivotal Trial of AVXS-101 for SMA Type 1

The gene therapy developer AveXis will start a pivotal clinical trial of AVXS-101 for people with SMA type 1. U.S. Food and Drug Administration officials agreed to the trial after AveXis submitted information the agency requested on the drug's manufacturing process and other matters. The request was made at a meeting the sides held in May. AveXis did not say in its announcement whether the pivotal trial would be a Phase 2 or Phase 3 study. The company has completed a Phase 1 trial of AVXS-101. Most pivotal trials are Phase 3, but occasionally they can be Phase 2. . AVXS-101 is a proprietary gene therapy for SMA types 1 and 2. Designed to deliver a functional copy of an SMN gene to motor neuron cells, it aims to prevent additional muscle degeneration. The pivotal trial in SMA type 1 – called STR1VE – will be an open-label, single-arm, single-dose, multi-center study. It will evaluate the safety and effectiveness of a one-time dose of AVXS-101 delivered intravenously or directly into the blood circulation. Researchers will administer a dose established in a Phase 1 trial that they confirmed with new analytical methods that the FDA reviewed. The dose was also extensively tested in a mouse model of SMA. AveXis expects to enroll in the trial at least 15 patients with SMA Type 1 younger than six months of age. One of the trial's primary objectives will be to see if AVXS-101 can help an 18-month-old infant sit without help for at least 30 seconds. Another primary objective will be to help an infant achieve event-free survival at 14 months of age, and to see whether AVXS-101 helps patients thrive — that is,  not requiring feeding support, tolerate thin liquids and maintain weight. Another secondary objective will be to help infants get off ventilator support at 18 months of age. Updates of these studies are expected at the end of the year.

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After 2-Year Hiatus, Novartis Resumes Branaplam Clinical Trial in SMA Type 1 Infants

Novartis will resume clinical development of branaplam to treat spinal muscular atrophy after a two-year pause brought on by safety concerns, the Swiss company announced in a letter published by Cure SMA. The ongoing clinical trial will start enrolling patients as soon as the research team obtains approvals by health authorities and the ethics committee. The study recruits infants younger than six months with type 1 SMA. All will receive branaplam, the name Novartis chose for its compound when reopening clinical investigations. While the study originally only included four European study centers — in Belgium, Germany, Denmark and Italy — Novartis said it plans to add more sites including some in the United States, following a green light from the U.S. Food and Drug Administration (FDA). The branaplam clinical trial halted new enrollments in May 2016 after simultaneous animal studies linked branaplam to unexpected nerve damage and other injuries. Infants already enrolled continued treatment and have been closely monitored. Novartis has worked with outside experts to understand the meaning of the animal findings. The fact that enrollment has resumed signals that Novartis — which has not commented on its relevance — no longer perceives the animal data as an immediate patient hazard. Besides resuming recruitment, the company has modified its trial design after considering feedback from the babies’ parents and study investigators. For instance, infants can now receive their weekly dose of branaplam orally, instead of via a feeding tube, which was the only option when the trial started. The company also added nerve tests to the trial as an additional safety procedure. As clinical development of branaplam continues, Novartis is also working with regulators to expand drug testing to include patients with other types of SMA.