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News
After decades of supportive-care-only management, Alexander disease patients finally have a real treatment option. The FDA has approved Zanvastro (zilganersen), an antisense oligonucleotide that targets the toxic GFAP protein buildup driving this ultra-rare, often fatal neurological disorder. The approval covers pediatric and adult patients — from infancy through adulthood — marking a landmark moment for a community of roughly 300 people in the U.S.
After decades with no approved therapies, patients with Alexander disease — a rare, progressive neurological disorder affecting fewer than 1 in a million people worldwide — have a first-ever disease-modifying treatment. The FDA approved Zanvastro (zilganersen), developed by Ionis Pharmaceuticals, for pediatric and adult patients of all ages, from infancy through adulthood. The drug works as an antisense oligonucleotide (ASO), reducing the abnormal production of glial fibrillary acidic protein (GFAP) before it accumulates in brain cells and causes irreversible neurological damage.
Efficacy data from a randomized, double-blind, placebo-controlled trial of 53 patients (ages 2–53) showed that Zanvastro significantly stabilized gait speed over 61 weeks compared to controls, who continued to decline. Younger children (ages 2–4) also showed improved gross motor skills while the control group worsened. The drug is administered as a 50 mg intrathecal injection every three months.
By the Numbers:
Why it matters: Beyond offering hope to a small but deeply affected patient community, Zanvastro's approval serves as proof of concept that ASO therapy can meaningfully alter the course of neurological diseases driven by toxic protein accumulation — potentially opening doors for other leukodystrophies and gain-of-function disorders.
