The functional integrity of effector immune cells is central to anti-tumor immune responses: The cytotoxic activity of CD8+ T cells serves as the primary force for eliminating tumor cells, and their functional exhaustion (manifested by restricted proliferation, reduced secretion of effector factors, and upregulation of exhaustion molecules such as PD-1) directly impairs immune responses (19, 20). The gene discussed is CD8A; the disease is neoplasm.