PDCD1 and neoplasm: Indeed, beyond CTLA-4 and PD-1, other immune check point molecules such as NKG2A, TIM (T cell immunoglobulin domain and mucin domain)-3, LAG (lymphocyte activation gene)-3, and TIGIT (T-cell immune-receptor with Ig and ITIM domains), which are expressed in CD8 and natural killer (NK) cells can also be referred to tumor resistance to immune cells (1, 2).