However, cytotoxic T lymphocytes (CD8+ T cells), the primary immune cell subset responsible for tumor clearance, often exhibit a dysfunctional phenotype characterized by decreased production of tumor-killing factors such as interferon-γ (IFN-γ), impaired proliferative potential, and elevated expression of exhaustion markers such as cytotoxic T lymphocyte-associated antigen 4 (CTLA-4).4 In light of this, the primary mechanism of current ICIs involves binding to immune checkpoints and blocking downstream signaling pathways, thereby reinvigorating CD8+ T cells. The gene discussed is CTLA4; the disease is neoplasm.