HAVCR2 and neoplasm: In the tumor microenvironment the activity of CD8+T cells can be hampered by immunosuppressive molecules, such as programmed cell death protein-1 (PD-1), cytotoxic T lymphocyte antigen-4 (CTLA-4), T cell immunoglobulin and mucin domain-containing protein 3 (TIM3), lymphocyte activation gene 3 protein (LAG3) and T-cell immune-receptor with immunoglobulin and ITIM domains (TIGIT), exhibiting an exhausted phenotype and function [1].