IL-2 (inhibitor)

Class

Computationally designed anti-IL-2 monoclonal antibody (human IgG1)

Pathway

Binds IL-2 directly to block engagement of the high-affinity trimeric receptor on Tregs and vasculature while preserving IL-2 signaling to effector T cells and NK cells via the dimeric receptor

Notes

original target text: IL-2 (CD25-binding portion of the cytokine itself, not the receptor) | original target text: IL-2 (CD25-binding portion of the cytokine itself, not the receptor) (inhibitor)

Interleukin-2 (IL-2) is a cytokine, a small signaling protein, that drives proliferation of immune cells including cytotoxic T cells and natural killer (NK) cells. It acts by binding receptor complexes on the cell surface. A high-affinity, three-part receptor containing a subunit called CD25 is found mainly on regulatory T cells (Tregs, which dampen immune responses) and on blood vessel lining cells. A separate two-part receptor, lacking CD25, is found on effector T cells and NK cells and requires higher IL-2 concentrations to engage. When IL-2 is given as a drug, it activates both receptor types, which expands Tregs and can damage vascular endothelium, producing fluid leakage into tissues, while also strengthening the immune attack against tumors. An antibody that binds IL-2 itself at the CD25-contact surface can block engagement of the three-part receptor without disrupting the two-part receptor interaction. This selectively removes the Treg-expanding and vessel-damaging signal while preserving stimulation of effector lymphocytes. This mechanism is relevant to cancer immunotherapy, where the goal is to amplify cytotoxic immune activity against tumors without the toxicities or immune suppression associated with broader IL-2 receptor engagement.