Xilio Therapeutics, Inc., a clinical-stage biotechnology company, engages in the discovery and development of masked immuno-oncology therapies. The company's pipeline includes XTX501, a bispecific PD-1 / masked IL-2, for patients with metastatic non-small cell lung cancer; Efarindodekin alfa, an investigational, masked IL-12, that is in Phase 2 clinical trial for patients with advanced solid tumors; and Vilastobart, an investigational tumor-activated, Fc-enhanced, high affinity binding anti-CTLA-4 monoclonal antibody. The company was founded in 2016 and is headquartered in Waltham, Massachusetts.