---
schema_version: "secwatch.filing_event.v1"
accession: "0001599298-25-000064"
form_type: "8-K"
ticker: "SMMT"
cik: "0001599298"
company_name: "Summit Therapeutics Inc."
filed_at: "2025-04-23T23:59:59+00:00"
generated_at: "2026-05-23T08:08:25.931587+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Ivonescimab + chemo beats tislelizumab + chemo in Phase III squamous NSCLC trial (HARMONi-6)

## Summary
- Primary endpoint PFS met: statistically significant and clinically meaningful improvement by BICR versus tislelizumab combo.
- PFS benefit observed in both PD-L1 positive and PD-L1 negative tumors.
- No new safety signals identified; full data set to be presented at upcoming medical conference.
- Second ivonescimab Phase III to show superiority over PD-(L)1 therapy (after HARMONi-2 in PD-L1+ monotherapy).
- Summit enrolling HARMONi-3 global Phase III vs pembrolizumab combo in 1L metastatic NSCLC with registrational intent.

## SEC filing metadata
- accession: 0001599298-25-000064
- form_type: 8-K
- ticker: SMMT
- cik: 0001599298
- company_name: Summit Therapeutics Inc.
- filed_at: 2025-04-23T23:59:59+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/1599298/000159929825000064/0001599298-25-000064-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1599298/000159929825000064/smmt-20250423.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001599298-25-000064
- JSON: https://secwatch.observer/filing/0001599298-25-000064.json
- Plain text: https://secwatch.observer/filing/0001599298-25-000064.txt

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