---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-25-177471"
form_type: "8-K"
ticker: "IOBTQ"
cik: "0001865494"
company_name: "IO Biotech, Inc."
filed_at: "2025-08-11T23:59:59+00:00"
generated_at: "2026-05-17T15:50:20.386245+00:00"
event_type: "other_material"
sentiment: "negative"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# IO Biotech Phase 3 Cylembio trial misses statistical significance; PFS improved 19.4 vs 11.0 mo

## Summary
- Primary endpoint PFS HR=0.77 (CI 0.58-1.00), p=0.056, missed significance threshold p≤0.045.
- Median PFS 19.4 months (Cylembio+pembrolizumab) vs 11.0 months (pembrolizumab alone).
- PD-L1 negative subgroup median PFS 16.6 vs 3.0 months (HR 0.54, nominal p=0.006).
- OS trend HR=0.79 (CI 0.57-1.10); company expects OS maturity in 6-9 months.
- Estimated cash $28.1M as of June 30, plus €12.5M drawn July 4; runway into Q1 2026.

## SEC filing metadata
- accession: 0001193125-25-177471
- form_type: 8-K
- ticker: IOBTQ
- cik: 0001865494
- company_name: IO Biotech, Inc.
- filed_at: 2025-08-11T23:59:59+00:00
- event_type: other_material
- sentiment: negative
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 2.02, 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1865494/000119312525177471/0001193125-25-177471-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1865494/000119312525177471/d454108d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-25-177471
- JSON: https://secwatch.observer/filing/0001193125-25-177471.json
- Plain text: https://secwatch.observer/filing/0001193125-25-177471.txt

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