FDA approves Ionis' Zanvastro as first treatment for rare Alexander disease

The U.S. FDA approved Ionis Pharmaceuticals’ Zanvastro (zilganersen) as the first disease-modifying treatment for Alexander disease, an ultrarare, progressive genetic leukodystrophy with no prior approved options beyond supportive care. The antisense oligonucleotide therapy targets the underlying biology by reducing production of the GFAP protein that accumulates in the brain’s supportive glial cells. It is approved for both pediatric and adult patients and is given as an intrathecal injection into the spinal canal every three months by trained healthcare professionals, a delivery approach that will require specialized pharmacy and care coordination. In pivotal trials, treated patients showed stabilized motor outcomes—such as walking speed at about 61 weeks—while control groups declined, with safety generally comparable and serious adverse events reported more often in controls. Analysts project the treatment could reach substantial sales, though pricing details were not immediately provided. Overall, the approval is being described by FDA neurology leadership and patient advocates as a major milestone for the Alexander disease community.