# Zilganersen PDUFA Event: Alexander disease

Canonical URL: https://biopharmsignal.com/pdufa-calendar/IONS/zilganersen-alexander-disease

Ticker: IONS

Company: Ionis Pharmaceuticals, Inc.

Event date: 2026-09-22

Event type: FDA Decision

Stage: PDUFA

Result: Pending

Application type: NDA

FDA decision expected. FDA assigned a September 22, 2026 PDUFA target action date to the zilganersen NDA.

## Event Timeline

### September 22, 2026 — FDA decision expected

FDA assigned a September 22, 2026 PDUFA target action date to the zilganersen NDA.

[Ionis — NDA acceptance and PDUFA date](https://ir.ionis.com/news-releases/news-release-details/ionis-announces-zilganersen-new-drug-application-alexander)

### April 21, 2026 — Additional pivotal-study results were presented

At the AAN annual meeting, Ionis reported additional treatment effects across clinically meaningful symptom domains and biomarker analyses.

[Ionis — Zilganersen data at AAN 2026](https://ir.ionis.com/news-releases/news-release-details/ionis-presents-new-data-pivotal-study-zilganersen-alexander)

### March 23, 2026 — FDA accepted the NDA with Priority Review

FDA accepted the application based on the pivotal Phase 1-3 study and granted Priority Review.

[Ionis — NDA acceptance and Priority Review](https://ir.ionis.com/news-releases/news-release-details/ionis-announces-zilganersen-new-drug-application-alexander)

### January 2026 — Ionis submitted the NDA

Ionis submitted the zilganersen NDA after the pivotal study demonstrated a clinically meaningful effect in children and adults with Alexander disease.

[Ionis — 2025 annual report and NDA submission](https://ir.ionis.com/static-files/2928a729-7c11-4c8c-a655-1457b0ed0437)

### December 2, 2025 — FDA granted Breakthrough Therapy designation

FDA granted Breakthrough Therapy designation based on the pivotal-study results.

[Ionis — Breakthrough Therapy designation](https://ir.ionis.com/news-releases/news-release-details/ionis-receives-us-fda-breakthrough-therapy-designation)

### September 22, 2025 — The pivotal study reported positive topline results

Zilganersen demonstrated statistically significant and clinically meaningful stabilization on the primary gait-speed endpoint, with key secondary endpoints favoring treatment.

[Ionis — Positive pivotal-study topline results](https://ir.ionis.com/node/33256)

## Regulatory Designations

- Priority Review FDA: [Ionis — NDA acceptance and Priority Review](https://ir.ionis.com/news-releases/news-release-details/ionis-announces-zilganersen-new-drug-application-alexander)

- Breakthrough Therapy FDA: [Ionis — Breakthrough Therapy designation](https://ir.ionis.com/news-releases/news-release-details/ionis-receives-us-fda-breakthrough-therapy-designation)

- Orphan Drug FDA: [Ionis — NDA acceptance and regulatory designations](https://ir.ionis.com/news-releases/news-release-details/ionis-announces-zilganersen-new-drug-application-alexander)

- Rare Pediatric Disease FDA: [Ionis — NDA acceptance and regulatory designations](https://ir.ionis.com/news-releases/news-release-details/ionis-announces-zilganersen-new-drug-application-alexander)

- Orphan Drug EMA: [Ionis — 2025 annual report and zilganersen regulatory status](https://ir.ionis.com/static-files/2928a729-7c11-4c8c-a655-1457b0ed0437)

## Related Pages

- IONS PDUFA calendar: https://biopharmsignal.com/pdufa-calendar/IONS.md

- IONS company profile: https://biopharmsignal.com/company/IONS.md

- PDUFA calendar: https://biopharmsignal.com/pdufa-calendar.md