---
schema_version: "secwatch.filing_event.v1"
accession: "0001140361-26-015801"
form_type: "8-K"
ticker: "IONS"
cik: "0000874015"
company_name: "IONIS PHARMACEUTICALS INC"
filed_at: "2026-04-21T23:59:59+00:00"
generated_at: "2026-05-15T05:15:00.729800+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.78
calibrated_materiality_score: 0.78
confidence: "high"
source: SEC EDGAR
---

# Ionis zilganersen meets primary endpoint in Alexander disease; PDUFA Sept 22, 2026

## Summary
- Primary endpoint met: gait speed stabilized vs control at Week 61 (LS mean diff 33.3%, p=0.041) in patients ≥5 years.
- GMFM-88 in children 2-4 years showed 22.9-point improvement vs control (nominal p=0.034).
- Key secondary endpoints (MBS, PGIS, PGIC, CGIC) consistently favored zilganersen over control.
- Serious TEAEs less frequent on zilganersen (37.5%) vs control (47.1%); most AEs mild/moderate.
- FDA Priority Review with PDUFA action date set for September 22, 2026.

## SEC filing metadata
- accession: 0001140361-26-015801
- form_type: 8-K
- ticker: IONS
- cik: 0000874015
- company_name: IONIS PHARMACEUTICALS INC
- filed_at: 2026-04-21T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.78
- calibrated_materiality_score: 0.78
- confidence: high
- sec_items: 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/874015/000114036126015801/0001140361-26-015801-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/874015/000114036126015801/ef20071051_8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001140361-26-015801
- JSON: https://secwatch.observer/filing/0001140361-26-015801.json
- Plain text: https://secwatch.observer/filing/0001140361-26-015801.txt

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