Therapeutic approaches of targeting Tregs could enhance CD8+ TILs and increase antigen presenting cell (APC) function, which may become as a potential strategy in many cancers.18 19 In this study, we determined the expression pattern of FOXP3 on TILs and its association with other checkpoints or markers in SCLC through immunohistochemistry (IHC) staining. The gene discussed is FOXP3; the disease is small cell lung carcinoma.