Certain studies have shown that in patients with colon cancer, tumor cells can evade cell lysis and cause an upregulation of the expression levels of immune checkpoint proteins, such as PD-1, CTLA-4, TIM-3, TIGIT, PD-L1, and galectin-9 by downregulating DNA methylation and repressing histone modification. This evidence concerns the gene HAVCR2 and malignant colon neoplasm.