Ionis Pharmaceuticals Inc. has received Breakthrough Therapy designation from the U.S. Food and Drug Administration (FDA) for zilganersen, an investigational treatment for Alexander disease (AxD). This designation is granted to therapies that treat serious or life-threatening conditions and have shown preliminary clinical evidence of substantial improvement over existing treatments. Zilganersen demonstrated statistically significant and clinically meaningful results in a pivotal study, including stabilization of gait speed in affected patients. Ionis plans to submit a New Drug Application (NDA) to the FDA in the first quarter of 2026 and is preparing to initiate an Expanded Access Program in the U.S. There are currently no approved disease-modifying treatments for Alexander disease.