Xilio Therapeutics, Inc.

Xilio Therapeutics, Inc. is a clinical-stage biotechnology company headquartered in Waltham, Massachusetts, founded in 2016. The company is dedicated to discovering and developing tumor-activated immuno-oncology (I-O) therapies with the goal of significantly improving outcomes for people living with cancer. Its core mission is to achieve deep and durable clinical responses without the systemic side effects often associated with current I-O treatments.

Leveraging its proprietary masking technology, Xilio Therapeutics aims to localize anti-tumor activity within the tumor microenvironment, thereby optimizing the therapeutic index of potent immune-modulating agents. The company's pipeline includes several investigational programs: XTX501, a bispecific PD-1 / masked IL-2 for non-small cell lung cancer and other solid tumors; masked T cell engagers targeting PSMA+STEAP1 for prostate cancer and CLDN18.2 for gastrointestinal and lung cancers; and efarindodekin alfa (masked IL-12) for advanced solid tumors, developed in partnership with Gilead Sciences. Additionally, Xilio is advancing vilastobart, a tumor-activated anti-CTLA-4 antibody, which has shown promising Phase 2 data in metastatic colorectal cancer.

René Russo, Pharm.D., serves as the President and CEO. In recent corporate developments, Xilio Therapeutics announced pipeline and business updates in March 2026, including an extended cash runway through the end of 2027. The company also completed a $40.0 million follow-on offering in February 2026 and continues to advance collaborations, including one with AbbVie for masked antibody-based immunotherapies. In April 2026, Cheryl R Blanchard was appointed to the board of directors. To address Nasdaq listing requirements, Xilio implemented a 1-for-14 reverse stock split in March 2026.