---
schema_version: "secwatch.filing_event.v1"
accession: "0001558370-25-011949"
form_type: "8-K"
ticker: "XLO"
cik: "0001840233"
company_name: "Xilio Therapeutics, Inc."
filed_at: "2025-09-09T23:59:59+00:00"
generated_at: "2026-05-17T07:21:24.560237+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# Xilio starts Phase 2 XTX301 (IL-12), gets $17.5M milestone from Gilead; cash extended to Q1 2027

## Summary
- Initiated patient dosing in Phase 2 of efarindodekin alfa (XTX301) for advanced solid tumors; RP2D selected.
- Achieved $17.5M development milestone under Gilead license agreement; expects payment in Q4 2025.
- As of June 30, 2025, cash and equivalents $121.6M; plus milestone extends cash runway into Q1 2027.
- Phase 1 data: two partial responses (1 confirmed, 1 unconfirmed) in late-line advanced solid tumors; generally well-tolerated.
- Gilead can elect to transition development after specified clinical data package for a $75M fee; Xilio eligible for up to $500M in milestones plus royalties.

## SEC filing metadata
- accession: 0001558370-25-011949
- form_type: 8-K
- ticker: XLO
- cik: 0001840233
- company_name: Xilio Therapeutics, Inc.
- filed_at: 2025-09-09T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.75
- calibrated_materiality_score: 0.75
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1840233/000155837025011949/0001558370-25-011949-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1840233/000155837025011949/xlo-20250909x8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001558370-25-011949
- JSON: https://secwatch.observer/filing/0001558370-25-011949.json
- Plain text: https://secwatch.observer/filing/0001558370-25-011949.txt

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