The tumor immune microenvironment consists of many host cells, including cytotoxic or regulatory T cells, dendritic cells, macrophages (M1 and M2), B cells, and myeloid-derived suppressor cells.14 Among these types, tumor-infiltrating lymphocytes (TILs) have long been reported to play a central role in antitumor immunity.15–17 Tumor-infiltrating lymphocytes consist of effector T cells, including CD4+ helper and CD8+ cytotoxic T cells that secrete cytokines and memory T cells that express an isoform called CD45RO.18 The gene discussed is CD4; the disease is neoplasm.