FDA Approves the First Drug for Alexander Disease, a Rare Brain Disorder With No Prior Treatment
Zanvastro, made by Ionis Pharmaceuticals, stabilized or improved motor function in a disease that previously had nothing to slow it. It ships as a spinal injection for children and adults alike.
Meridians Life Desk
Published 8 September 2026 · Updated 8 September 2026 · 4 min read
HealthThe short answer
- The FDA approved Zanvastro (zilganersen) on September 3, 2026, the first disease-modifying treatment for Alexander disease.
- Alexander disease is an ultra-rare, progressive brain disorder caused by GFAP gene mutations, affecting fewer than 1 in a million people.
- In the pivotal trial, walking speed held steady in treated patients while it fell 33% in the untreated control group.
- The drug is approved for both children and adults and is given as an injection into the spinal canal by a trained clinician.
The Food and Drug Administration approved Zanvastro (zilganersen) on September 3, 2026, making it the first and only disease-modifying treatment for Alexander disease. Until now, families with the diagnosis had no drug aimed at the disease itself, only treatments for individual symptoms.
What Alexander disease does
Alexander disease is caused by mutations that lead to a buildup of abnormal glial fibrillary acidic protein in the brain's support cells, damaging the nervous system over time. The FDA describes it as affecting fewer than 1 in a million people. It can cause seizures, developmental delays, difficulty walking, muscle weakness and increased pressure inside the skull, with severity ranging from infancy through adulthood.
What the trial found
- In patients age 5 and older with existing walking difficulties, walking speed stayed stable in the treated group over 61 weeks, while it declined 33% in the untreated control group, according to STAT News.
- Children age 2 to 4 showed improvements in motor skills including standing, walking, running and jumping, while untreated children in the comparison group declined, per the FDA.
- Data on children under 2 were limited, given how rare the disease is; the FDA supported approval for that group using pharmacokinetic modeling and safety data from older patients.
How it's given, and the risks
Zanvastro is delivered as an injection into the spinal canal, administered periodically by a trained healthcare professional. The most common side effects are vomiting, back pain, cough, headache and post-lumbar puncture syndrome. Aseptic meningitis has also been reported in patients, and the FDA advises watching for meningitis-like symptoms after each dose.
Sources
Every factual claim above is traceable to these documents. Check them — that is why they are here.
- FDA Approves First Drug to Treat Alexander DiseaseU.S. Food and Drug Administration
- FDA approves Zanvastro from Ionis, first drug for Alexander diseaseSTAT News
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Meridians Life Desk is an editorial desk at Meridians, not an individual. A desk byline means the article was produced and fact-checked to that desk's published standards. Read our editorial standards and corrections policy.
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