The FDA approved Ionis Pharmaceuticals’ antisense therapy Zanvastro (zilganersen) for Alexander disease in pediatric and adult patients, establishing the first disease-modifying treatment for this ultra-rare neurologic disorder. The RNA-targeted drug is designed to reduce glial fibrillary acidic protein (GFAP) production. In the pivotal program highlighted in reporting around the decision, Zanvastro met its primary endpoint with statistically significant stabilization in adults and showed benefit in gross motor function in younger patients. Ionis said the therapy will be available in the coming weeks and received a rare pediatric disease priority review voucher. For biotech operators, the approval underscores how antisense platforms continue to translate into discrete neurology indications with clear biomarker biology, while also reinforcing the FDA’s willingness to support approvals in small, defined patient populations.