FDA approval file confirms Zanvastro details for Alexander disease

The FDA's drug application database confirms that Zanvastro (zilganersen sodium) was approved under NDA220210 on September 3, 2026, with the agency issuing an approval letter dated September 4 and a product label dated September 8, according to the FDA's application records.

The approval makes Zanvastro the first FDA-approved treatment for Alexander disease and the first therapy to directly target the protein buildup that drives the disease.¹ Alexander disease stems from mutations in the gene that produces glial fibrillary acidic protein, or GFAP. When this protein is abnormal, it builds up in the brain's supportive cells and damages the nervous system over time, and the disease can cause seizures, loss of developmental milestones, difficulty walking, muscle weakness, and increased pressure in the brain.¹ It affects less than 1 in a million people.¹

Zanvastro works as an antisense oligonucleotide that reduces production of the abnormal GFAP protein before it can accumulate and cause further damage.¹ Per the FDA database, it is formulated as a 56 mg/2.8 mL (20 mg/mL) intrathecal solution² and, per the press release, is administered as an injection into the spinal canal every three months by a trained healthcare professional.¹

Approval relied on a multicenter, randomized, controlled clinical study (NCT04849741) enrolling 49 pediatric and adult patients with Alexander disease 2 years of age and older, and an open-label substudy of 4 patients less than 2 years of age.¹ Patients aged 5 and older with measurable walking difficulty at baseline showed significantly better walking speed at 61 weeks compared with untreated patients.¹ For younger children, a broader motor skills assessment covering standing, walking, running, and jumping was used instead, and treated children improved on this measure while control patients declined.¹

Common side effects include vomiting, back pain, cough, headache, and post-lumbar puncture syndrome, and aseptic meningitis has been reported in treated patients.¹ The drug carries Orphan Drug, Fast Track, Breakthrough Therapy, and Rare Pediatric Disease and Priority Review Voucher designations.¹