Induction of CD3+ and FoxP3+ T Cells in Left-sided Colorectal Tumors after UFT/LV Chemotherapy

Abstract

Background/Aim: Immune checkpoint inhibitors are mainly used for right-sided, microsatellite instability-high colorectal tumors. In this study, the effects of oral uracil–tegafur plus leucovorin (UFT/LV) chemotherapy on the gene expressions of four immunotherapy targets and the amounts of tumor-infiltrating lymphocytes (TILs) were investigated. Patients and Methods: Data of 260 patients with stage II or stage III colorectal cancer were analyzed. Gene expression and amount of TILs were evaluated using real-time reverse transcription polymerase chain reaction (CRT-PCR) assay and immunohistochemical staining, respectively. Results: Expression of CTLA4 and LAG3 in tumor tissues was significantly increased after UFT/LV chemotherapy, but only in left-sided tumors. The percentage of high-TIL, high-CD3 and high-FoxP3 patients in the UFT/LV group was significantly higher than that in the control group, only in left-sided tumors. Conclusion: The increase in TILs count, especially of CD3+ T cells and FoxP3+ regulatory T cells, after UFT/LV chemotherapy were specific to left-sided colorectal cancers.