---
schema_version: "secwatch.filing_event.v1"
accession: "0001140361-25-035634"
form_type: "8-K"
ticker: "IONS"
cik: "0000874015"
company_name: "IONIS PHARMACEUTICALS INC"
filed_at: "2025-09-22T23:59:59+00:00"
generated_at: "2026-05-17T06:03:32.384621+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Ionis reports positive pivotal study results for zilganersen in Alexander disease; NDA planned Q1 2026

## Summary
- Primary endpoint met: gait speed improved 33.3% vs control (p=0.0412) at week 61 in 50 mg cohort.
- No approved disease-modifying treatments for Alexander disease; first investigational drug to show positive impact.
- Safety profile favorable: most adverse events mild/moderate; SAEs numerically lower in zilganersen arm.
- NDA submission to FDA targeted for Q1 2026; evaluating U.S. Expanded Access Program.

## SEC filing metadata
- accession: 0001140361-25-035634
- form_type: 8-K
- ticker: IONS
- cik: 0000874015
- company_name: IONIS PHARMACEUTICALS INC
- filed_at: 2025-09-22T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/874015/000114036125035634/0001140361-25-035634-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/874015/000114036125035634/ef20055880_8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001140361-25-035634
- JSON: https://secwatch.observer/filing/0001140361-25-035634.json
- Plain text: https://secwatch.observer/filing/0001140361-25-035634.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.