XTX401 (Xilio Therapeutics)

XTX401 is an investigational, tumor-activated, PD-1-directed interleukin-2 (IL-2) fusion protein developed by Xilio Therapeutics. Utilizing the company's proprietary GPS (Geographically Precise Solutions) platform, XTX401 is engineered as a masked immunocytokine designed to remain inactive in systemic circulation and become selectively activated by proteases within the tumor microenvironment. The molecule comprises an anti-PD-1 antibody fused to an IL-2 variant. By targeting PD-1, the drug localizes to tumor-infiltrating lymphocytes, where protease cleavage releases the IL-2 to stimulate local immune responses. This dual mechanism aims to combine checkpoint inhibition with potent cytokine-mediated T-cell and NK-cell activation while avoiding the severe systemic toxicities, such as vascular leak syndrome, typically associated with high-dose IL-2 therapy.

Other names

tumor-activated PD-1-directed interleukin-2tumor-activated PD-1-directed IL-2PD-1-directed tumor-activated IL-2PD1-directed tumor-activated IL-2PD 1-directed tumor-activated IL-2