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# Priority Review for Ionis Alexander Disease Drug
- URL: https://www.fdaweb.com/priority-review-for-ionis-alexander-disease-drug/
- Published: 2026-03-23T12:00:00.000Z
- Updated: 2026-09-14T13:35:58.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5160859

FDA accepts for priority review an Ionis Pharmaceuticals NDA for zilganersen, an experimental treatment for Alexander disease. The agency set a user fee review action target date of 9/22.

Alexander disease is described as a progressive neurological disorder that primarily affects children and leads to severe motor and cognitive decline, loss of independence, and premature death. There are currently no disease-modifying therapies available.

Ionis says the submission is supported by data from a pivotal clinical trial in which zilganersen demonstrated statistically significant and clinically meaningful stabilization in patients’ gait speed, as measured by the 10-Meter Walk Test at 61 weeks. The treatment also showed favorable results across secondary measures, including communication, adaptive function, and symptoms such as seizures and sleep disturbances, with a generally well-tolerated safety profile.

Zilganersen is an antisense oligonucleotide therapy designed to reduce production of glial fibrillary acidic protein, a substance that accumulates abnormally in patients with the disease and drives neurological damage, according to the company.