What the trial was testing
The STEER enrolled 126 patients with spinal muscular atrophy. The study was sponsored by Novartis Pharmaceuticals and tracked outcomes across the full group of patients who matched the trial's eligibility profile.
It was a large trial designed to confirm whether the treatment works well enough for wider use. Trials at this stage are designed to produce evidence regulators and physicians can act on — not just observations to follow up later.
What the results showed
Children receiving the gene therapy improved their motor skills by nearly 2 points more on a standard muscle function test.
Nature medicine · 2026 · NCT05089656
These findings — that children who got the gene therapy improved their ability to move nearly 2 points more than those who didn't — were published in the Nature medicine and represent the headline result of the study.
Researchers tracked outcomes across 126 patients enrolled in the trial. The result was consistent enough across the group that the team felt confident reporting it.
What this means for patients
For patients with spinal muscular atrophy, this result changes the calculus on what to ask their care team about. Whether it changes day-to-day care depends on factors like disease subtype, prior treatments, and where the patient is in their care journey.
What you can do now
This one-time gene therapy is FDA-approved for spinal muscular atrophy under the brand name Zolgensma, though this specific delivery method (through the spine) may have different approval status. If your child has spinal muscular atrophy, talk to your neuromuscular specialist about whether this treatment approach is available and appropriate for your child's specific situation.
Eligibility for the treatments mentioned above depends on specific test results and clinical history. Bring this summary, the trial name, and your most recent labs or pathology report to your next visit.
Open spinal muscular atrophy trials
A Study of Risdiplam in Participants With Type I and Type II Spinal Muscle Atrophy (SMA)
This multicenter, non-interventional, prospective study with a retrospective component aims to evaluate the real-world clinical outcomes, safety profile, and motor function improvements of Risdiplam treatment in participants with Type I and Type II Spinal Muscle Atrophy over 24 months of treatment. The study will allow retrospective collection of medical history data and previous participants visits from the medical records.
Study of Safety, Tolerability and Efficacy of GB221 in Infants With Spinal Muscular Atrophy Type 1
GB221 is a gene therapy that delivers a working SMN1 gene to the motor neurons of people with spinal muscular atrophy (SMA) Type 1. This study will evaluate the safety, tolerability and efficacy of GB221 in two groups: 1. participants aged from 2 weeks to younger than 12 months presenting with symptoms of SMA Type 1 who have never received a treatment OR are receiving the drug risdiplam 2. participants aged from 2 weeks to younger than 5 months who are at risk of developing SMA Type 1 (presymptomatic) and have never received treatment OR are receiving the drug risdiplam.