The U.S. Food and Drug Administration has approved Zanvastro (zilganersen) for children and adults with Alexander disease, marking a major development for patients affected by the ultra-rare and progressive neurological disorder.

New Treatment Targets Underlying Disease

Zanvastro, developed by Ionis Pharmaceuticals, is the first FDA-approved disease-modifying treatment for Alexander disease. The RNA-targeted therapy is designed to reduce production of excess glial fibrillary acidic protein, or GFAP, which is associated with the underlying disease mechanism.

Alexander disease can cause progressive problems involving movement, cognitive function and muscle control. Because the disease is extremely rare, patients have historically relied mainly on treatments aimed at managing individual symptoms rather than addressing the underlying biology.

The FDA approval followed a clinical study involving 54 participants between 1.5 and 53 years old across 13 sites in eight countries. The pivotal study found a statistically significant improvement in gait-speed stabilization among participants aged five and older receiving the 50-mg dose.

Rare Disease Care Enters New Phase

The approval also comes with a Rare Pediatric Disease Priority Review Voucher, part of an FDA program designed to encourage development of therapies for serious diseases affecting children.

Ionis said Zanvastro is expected to become available in the United States in the coming weeks, potentially giving families affected by Alexander disease a new treatment option.

The approval represents a significant milestone in rare-disease care and highlights the growing role of RNA-targeted medicines in treating serious neurological conditions.