The FDA has approved Zanvastro (zilganersen) from Ionis Pharmaceuticals — the first disease-modifying therapy ever approved for Alexander disease, an ultra-rare and devastating neurological disorder.
Alexander disease affects roughly one in one to three million people. It’s caused by abnormal activity of the GFAP gene, which leads to a toxic protein buildup in astrocytes (star-shaped support cells in the brain). Patients face seizures, muscle weakness, progressive loss of mobility, and swallowing difficulty. Zanvastro is an antisense oligonucleotide designed to reduce GFAP production at its source.
What the trial showed
In the pivotal trial, Zanvastro significantly stabilized walking speed in patients over age five compared with controls at week 61, with similar promise in children aged two to four. It’s approved for both pediatric and adult patients. Ionis plans a US rollout “in the coming weeks,” with insurance-assistance and affordability programs; pricing wasn’t disclosed. (Recordati holds ex-US rights.)
Why it matters
For families facing a relentless, previously untreatable disease, a therapy that slows the loss of mobility is a genuine first. It’s also a milestone for Ionis — its first independently launched neurology drug — and another example of antisense technology reaching ultra-rare diseases that larger companies often overlook.