Xilio Therapeutics, Inc. (Nasdaq: XLO), a clinical-stage biotechnology company discovering and developing masked immuno-oncology therapies for people living with cancer, today announced pipeline progress and business updates and reported financial results for the fourth quarter and full year ended December 31, 2025.

In preclinical studies, XTX501 demonstrated robust monotherapy activity (including in settings insensitive to PD-1 therapy) and tumor-selective pharmacodynamics consistent with its intended mechanism of action.

  • Xilio is currently advancing XTX501 through investigational new drug (IND)-enabling studies and plans to submit an IND application for XTX501 in the middle of 2026.
  • Xilio plans to initiate a Phase 1 trial for XTX501 in the second half of 2026 and report initial Phase 1 data in the second half of 2027, subject to clearance of the IND by the U.S. Food and Drug Administration.
  • Xilio plans to initially evaluate XTX501 in patients with metastatic non-small cell lung cancer before expanding development to other solid tumor types, including tumors that are insensitive to PD-1 therapy. The company believes XTX501 also has the potential to be a foundational "backbone" therapy for combination treatment with other agents.