---
schema_version: "secwatch.filing_event.v1"
accession: "0001599298-26-000081"
form_type: "8-K"
ticker: "SMMT"
cik: "0001599298"
company_name: "Summit Therapeutics Inc."
filed_at: "2026-09-15T12:44:39+00:00"
generated_at: "2026-09-15T12:50:23.783507+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Summit reports consistent OS benefit for ivonescimab in HARMONi; HARMONi-2 OS data positive

## Summary
- Updated HARMONi OS analysis: global ITT HR 0.76 (95% CI 0.61-0.95; p=0.0151), median OS 16.8 vs 14.0 months.
- Western subgroup OS HR 0.76 (95% CI 0.52-1.10), consistent with global; median follow-up 23.2 months.
- HARMONi-2 (Akeso-sponsored) OS: HR 0.73 (95% CI 0.57-0.95; p=0.009) vs pembrolizumab; median OS 30.8 vs 22.6 months.
- No new safety signals; BLA PDUFA date for ivonescimab is November 14, 2026.

## SEC filing metadata
- accession: 0001599298-26-000081
- form_type: 8-K
- ticker: SMMT
- cik: 0001599298
- company_name: Summit Therapeutics Inc.
- filed_at: 2026-09-15T12:44:39+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1599298/000159929826000081/0001599298-26-000081-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1599298/000159929826000081/smmt-20260915.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001599298-26-000081
- JSON: https://secwatch.observer/filing/0001599298-26-000081.json
- Plain text: https://secwatch.observer/filing/0001599298-26-000081.txt

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