---
schema_version: "secwatch.filing_event.v1"
accession: "0001558370-23-019579"
form_type: "8-K"
ticker: "XLO"
cik: "0001840233"
company_name: "Xilio Therapeutics, Inc."
filed_at: "2023-12-07T23:59:59+00:00"
generated_at: "2026-06-07T16:22:40.620133+00:00"
event_type: "other_material"
sentiment: "neutral"
materiality_score: 0.6
calibrated_materiality_score: 0.6
confidence: "high"
source: SEC EDGAR
---

# Xilio initiates Phase 1 combo trial of XTX101 with atezolizumab; reports updated monotherapy data with 33% DCR

## Summary
- Initiated enrollment for Phase 1 dose escalation of XTX101 in combination with atezolizumab; RP2D for combo expected Q2 2024.
- Updated monotherapy data at RP2D (150 mg Q6W) show 33% disease control rate in late-line/IO refractory patients; no discontinuations due to TRAE.
- Confirmed partial response in PD-L1 negative NSCLC patient continued through 36 weeks with complete resolution of liver metastases.
- Plans to initiate Phase 2 trial in MSS CRC in Q3 2024, subject to obtaining sufficient additional capital.
- Preliminary PK demonstrates tumor-selective activation: 96% in melanoma, 73% in liver metastasis vs 13% peripheral activation.

## SEC filing metadata
- accession: 0001558370-23-019579
- form_type: 8-K
- ticker: XLO
- cik: 0001840233
- company_name: Xilio Therapeutics, Inc.
- filed_at: 2023-12-07T23:59:59+00:00
- event_type: other_material
- sentiment: neutral
- materiality_score: 0.6
- calibrated_materiality_score: 0.6
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1840233/000155837023019579/0001558370-23-019579-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1840233/000155837023019579/xlo-20231207x8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001558370-23-019579
- JSON: https://secwatch.observer/filing/0001558370-23-019579.json
- Plain text: https://secwatch.observer/filing/0001558370-23-019579.txt

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