---
schema_version: "secwatch.filing_event.v1"
accession: "0001140361-25-008178"
form_type: "8-K"
ticker: "IONS"
cik: "0000874015"
company_name: "IONIS PHARMACEUTICALS INC"
filed_at: "2025-03-12T23:59:59+00:00"
generated_at: "2026-05-24T22:56:39.519380+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.8
calibrated_materiality_score: 0.8
confidence: "high"
source: SEC EDGAR
---

# Ionis licenses sapablursen to Ono for $280M upfront, up to $660M milestones and mid-teen royalties

## Summary
- $280M upfront payment; up to $660M in development, regulatory and sales milestones.
- Sapablursen is an investigational RNA-targeted medicine for polycythemia vera; has FDA orphan drug and Fast Track designations.
- Ono receives exclusive global rights; Ionis completes Phase 2 IMPRSSION study, Ono handles subsequent development and commercialization.
- Ionis eligible for royalties in the mid-teen percentage range on annual net sales of sapablursen.
- Transaction subject to Hart-Scott-Rodino Antitrust Improvements Act (HSR) review.

## SEC filing metadata
- accession: 0001140361-25-008178
- form_type: 8-K
- ticker: IONS
- cik: 0000874015
- company_name: IONIS PHARMACEUTICALS INC
- filed_at: 2025-03-12T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.8
- calibrated_materiality_score: 0.8
- confidence: high
- sec_items: 1.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/874015/000114036125008178/0001140361-25-008178-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/874015/000114036125008178/ef20045255_8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001140361-25-008178
- JSON: https://secwatch.observer/filing/0001140361-25-008178.json
- Plain text: https://secwatch.observer/filing/0001140361-25-008178.txt

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