CD8α (targeting) / IL-2 receptor (agonism)

Class

CD8α-guided IL-2 immunocytokine

Pathway

Anchors an engineered IL-2 payload to CD8+ T cells to selectively expand cytotoxic T cells while reducing systemic IL-2 toxicity; combined clinically with PD-1/TIGIT bispecific rilvegostomig

This mechanism combines two components: a targeting arm that recognizes CD8α, a marker found on cytotoxic T cells (the immune cells responsible for directly killing tumor or infected cells), and a modified interleukin-2 (IL-2) payload, a signaling protein that drives T cell proliferation and activation. Native IL-2 is a foundational immune growth factor, but administering it systemically activates immune cells broadly, including regulatory T cells that suppress immune responses, and causes significant toxicity such as vascular leakage. By physically linking an engineered, lower-potency IL-2 to an antibody fragment that binds CD8α, this approach delivers the growth signal preferentially to cytotoxic T cells already positioned to attack disease, rather than to the whole body. The biological rationale is to expand and sustain a cytotoxic T cell response against tumors while limiting the off-target expansion of suppressive cell populations and reducing systemic exposure to free cytokine. This class of molecule, called an immunocytokine, is relevant across oncology, where boosting T cell numbers and activity can improve tumor control, particularly when paired with agents that remove inhibitory checkpoints on T cell function, allowing an already unleashed T cell to also receive a proliferative signal.