Xilio Therapeutics Announces Initiation of Patient Dosing in Phase 1/2 Clinical Trial of XTX202 for the Treatment of Patients with Solid Tumors


Xilio Therapeutics, Inc. (Nasdaq: XLO), a biotechnology company developing tumor-selective immuno-oncology therapies for people living with cancer, today announced that the first patient has been dosed in the company’s Phase 1/2 clinical trial evaluating XTX202 for the treatment of solid tumors. XTX202 is a modified form of IL-2 that is designed to localize activity in the tumor microenvironment (TME), with the goal of overcoming the known tolerability challenges of existing IL-2 therapies while achieving enhanced anti-tumor activity.

“We are pleased to begin patient dosing in our Phase 1/2 clinical trial with XTX202, a novel tumor selective IL-2 candidate with the potential to increase the therapeutic benefit of IL-2,” said Marty Huber, M.D., president of research and development and chief medical officer of Xilio Therapeutics. “XTX202 has been designed to be active only within the TME, with the goal of reducing dose limiting toxicity and enhancing anti-tumor activity. We look forward to advancing this trial to further our understanding of XTX202 as a potential therapy for the treatment of people living with cancer.”

Leveraging its proprietary geographically precise solutions (GPS) platform, Xilio designed XTX202 to be masked with a protein domain to prevent binding activity until the protein domain is cleaved off by TME-associated proteases. XTX202 is intended to be activated selectively in the TME, resulting in localized anti-tumor activity without dose-limiting toxicities. In preclinical studies, XTX202 exhibited tumor-selective biological activity and anti-tumor activity comparable to aldesleukin, a high-dose IL-2 therapy, at its maximum tolerated dose, while minimizing the severe toxicity observed with aldesleukin. In non-human primate models, XTX202 was well-tolerated at doses up to 10 mg/kg weekly.

The Phase 1/2 clinical trial is a first-in-human, multi-center, open-label trial that will evaluate XTX202 as a monotherapy in patients with advanced solid tumors. The Phase 1 portion of the trial consists of a dose-escalation monotherapy cohort designed to evaluate the safety and tolerability of XTX202 and determine the recommended Phase 2 dose. Following completion of the Phase 1 portion, Xilio plans to initiate Phase 2 expansion cohorts with XTX202 monotherapy evaluating the objective response rate in patients with renal cell carcinoma or melanoma who previously received an anti-PD-1 treatment regimen. Xilio also plans to initiate one or more additional Phase 1 trials aimed at demonstrating utility of XTX202 in combinations with other agents such as anti-PD-1 agents or tyrosine kinase inhibitors.

More information on the trial can be found at https://clinicaltrials.gov (NCT05052268).