---
schema_version: "secwatch.filing_event.v1"
accession: "0001599298-26-000043"
form_type: "8-K"
ticker: "SMMT"
cik: "0001599298"
company_name: "Summit Therapeutics Inc."
filed_at: "2026-06-01T10:57:20+00:00"
generated_at: "2026-06-01T11:00:34.911587+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Ivonescimab: 70.8% ORR in mCRC Phase II; HARMONi-6 OS HR 0.66 vs tislelizumab

## Summary
- Phase II AK112-206 in 1L mCRC: ORR 70.8%, DCR 100.0% in evaluable patients (n=48); 9-month PFS rate 76.1% for 20 mg/kg arm.
- HARMONi-6 Phase III in squamous NSCLC: OS HR 0.66 (p=0.0017) vs tislelizumab + chemo; 24-month OS rates 64.7% vs 48.6%.
- Ivonescimab + chemo reduced risk of death by 34% vs tislelizumab; first Phase III to show significant OS benefit over anti-PD-1 + chemo in 1L NSCLC.
- Safety profiles manageable; no new safety signals; TRAEs leading to discontinuation in HARMONi-6: 5.3% vs 4.5%.
- Data presented at ASCO 2026; HARMONi-6 results simultaneously published in The Lancet; Summit to host conference call June 1.

## SEC filing metadata
- accession: 0001599298-26-000043
- form_type: 8-K
- ticker: SMMT
- cik: 0001599298
- company_name: Summit Therapeutics Inc.
- filed_at: 2026-06-01T10:57:20+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/1599298/000159929826000043/0001599298-26-000043-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1599298/000159929826000043/smmt-20260530.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001599298-26-000043
- JSON: https://secwatch.observer/filing/0001599298-26-000043.json
- Plain text: https://secwatch.observer/filing/0001599298-26-000043.txt

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