The FDA has approved Ionis Pharmaceuticals’ antisense therapy Zanvastro (zilganersen) for Alexander disease in pediatric and adult patients, marking the first disease-modifying treatment for the ultra-rare, progressive neurological disorder. The approval follows pivotal trial results showing stabilization of gait speed in treated patients compared with decline in the control arm, with supportive functional signals across younger age groups. Zanvastro is administered intrathecally at 50 mg on a quarterly basis and works by reducing production of GFAP (glial fibrillary acidic protein), the protein implicated in Alexander disease pathophysiology. Ionis will now move Zanvastro toward commercial availability, supported by a patient access and support program. The approval also gives Ionis a rare pediatric disease priority review voucher, underscoring regulators’ emphasis on expedited pathways for conditions with limited or no therapeutic options. The launch will be notable for being the company’s first wholly owned neurology product without a commercialization partner.