protein-engineered interleukin-2 XTX202

A modified form of the recombinant form of human endogenous cytokine interleukin-2 (IL-2), that is masked with a protein domain, with potential immunoregulatory and antineoplastic activities. Upon administration of protein-engineered IL-2 XTX202, IL-2 is bound to the protein and pharmacologically inactive. IL-2 does not become active until cleaved by specific proteases in the tumor microenvironment (TME). Upon proteolytic cleavage, unbound and active IL-2 locally binds to the IL-2 receptor beta (CD122) and gamma (CD132) subunits (IL2Rb/g) that are expressed on CD8+ T-effector cells and natural killer (NK) cells, thereby activating IL2R-mediated signaling within these immune cells. The activation of T cells and NK cells mediate cytolytic immune responses against tumor cells causing tumor cell destruction and inhibition of tumor cell proliferation. XTX202 does not bind to IL-2 receptor alpha (IL-2Ra) and does not cause IL-2Ra-mediated toxicities. The selective activation in the TME enhances the IL-2-mediated cytolytic responses against tumor cells while sparing the unwanted effects of systemic, peripheral immune activation.