FDA approves first drug for Alexander disease

By Atlas Watchline Staff · Regulatory · September 3, 2026

The FDA has approved Zanvastro (zilganersen) injection for Alexander disease in pediatric and adult patients, the first approved treatment for the rare neurological disorder.

The U.S. Food and Drug Administration said Zanvastro (zilganersen) injection is the first FDA-approved treatment for Alexander disease and the first therapy designed to directly target the protein buildup believed to drive the condition. The agency said the drug is approved for patients from infancy through adulthood.

The FDA said there had been no approved treatment options for Alexander disease before this approval, leaving supportive care as the main option. Alexander disease is a rare, progressive neurological disorder caused by mutations in the gene that produces glial fibrillary acidic protein, or GFAP, according to the agency.

The FDA said abnormal GFAP accumulates in the brain’s supportive cells and can damage the nervous system over time. It said the disease affects less than 1 in a million people and can lead to seizures, loss of developmental milestones, difficulty walking, muscle weakness and increased pressure in the brain.

Zanvastro is an antisense oligonucleotide designed to reduce production of the abnormal GFAP protein before more of it can build up. The drug is given as an injection into the spinal canal every three months by a trained healthcare professional, the FDA said.

The agency said it evaluated safety and efficacy in a multicenter, randomized, controlled study identified as NCT04849741 involving 49 pediatric and adult patients age 2 years and older, along with an open-label substudy of four patients under age 2. In patients age 5 and older who had walking difficulty at baseline, the FDA said the treated group had significantly better walking speed at 61 weeks than untreated patients. In children ages 2 to 4, the treated group improved on a broader motor-skills measure while the control group declined.

For patients under age 2, the FDA said direct trial data were limited, but pharmacokinetic modeling and safety data supported extending the indication to that age group. The agency also said the indication covers infancy through adulthood because the disease is rare and affects people across a wide range of ages.

Emily Freilich, director of the Division of Neurology I in the FDA’s Center for Drug Evaluation and Research, said there had previously been no approved treatment options and only supportive care. She said the approval offers the first therapy that addresses the underlying cause of the disease.

The FDA said the most common side effects are vomiting, back pain, cough, headache and post-lumbar puncture syndrome. It also said aseptic meningitis has been reported and advised patients and caregivers to contact healthcare providers if symptoms consistent with meningitis develop.

The agency said Zanvastro received Orphan Drug, Fast Track, Breakthrough Therapy, Rare Pediatric Disease and Priority Review Voucher designations. The approval was granted to Ionis Pharmaceuticals, Inc.

The drug will now be available under the FDA-approved label, with use and monitoring guided by healthcare professionals trained to give injections into the spinal canal.

Sources

• FDA press release: FDA approves first drug to treat Alexander disease

Editorial note: This article was prepared with AI assistance and includes source attribution for reader review.

This is the AMP version of the article. Read the full article on Atlas Watchline.