---
schema_version: "secwatch.filing_event.v1"
accession: "0001140361-24-028247"
form_type: "8-K"
ticker: "IONS"
cik: "0000874015"
company_name: "IONIS PHARMACEUTICALS INC"
filed_at: "2024-05-31T23:59:59+00:00"
generated_at: "2026-06-01T07:18:19.376834+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# Ionis reports positive Phase 3 results for donidalorsen in HAE; 81% attack reduction vs placebo

## Summary
- Donidalorsen met primary endpoint: 81% lower monthly HAE attack rate with Q4W dosing vs placebo (p<0.001) over 24 weeks.
- OASISplus OLE showed continued improvement: 93% (Q4W) and 92% (Q8W) attack rate reduction from baseline after one year.
- Switch cohort: patients switching from prior prophylactic to donidalorsen had 62% further reduction in mean monthly attack rates; 84% preferred donidalorsen.
- Donidalorsen was well-tolerated; no related serious TEAEs. Injection site reactions most common AE.
- Ionis plans to file NDA with FDA this year; Otsuka preparing MAA in Europe for donidalorsen.

## SEC filing metadata
- accession: 0001140361-24-028247
- form_type: 8-K
- ticker: IONS
- cik: 0000874015
- company_name: IONIS PHARMACEUTICALS INC
- filed_at: 2024-05-31T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.75
- calibrated_materiality_score: 0.75
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/874015/000114036124028247/0001140361-24-028247-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/874015/000114036124028247/ef20030319_8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001140361-24-028247
- JSON: https://secwatch.observer/filing/0001140361-24-028247.json
- Plain text: https://secwatch.observer/filing/0001140361-24-028247.txt

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