Ionis Pharmaceuticals won U.S. FDA approval for Zanvastro (zilganersen), the first disease-modifying therapy for Alexander disease in both pediatric and adult patients. The antisense RNA therapy is designed to reduce glial fibrillary acidic protein (GFAP) production, targeting the disease mechanism rather than symptoms. The approval follows pivotal trial results showing stabilization in walking speed using the 10-Meter Walk Test in patients aged 5 and older, with a reported 33.3% least-square mean difference versus control at week 61. Safety findings indicated serious adverse events were more frequent in the control arm than in the Zanvastro arm. Ionis said Zanvastro will be available in the coming weeks. The company also received a rare pediatric disease priority review voucher tied to the approval, setting up a new commercial and clinical pathway for Ionis’ first wholly owned neurology product.