Ionis Pharmaceuticals announced that its antisense oligonucleotide candidate, zilganersen, demonstrated significant clinical benefits in a pivotal phase 3 trial for Alexander disease, a rare neurogenetic disorder. The treatment improved gait speed as assessed by standardized walking tests compared to control, evidencing disease-modifying potential. Ionis plans to file for regulatory approval in early 2026. This marks the first drug to show efficacy in this fatal rare neurological condition, representing an important therapeutic advance.