CTLA4 and neoplasm: Immune checkpoint molecules, such as programmed death receptor 1 (PD-1), programmed death-ligand 1 (PD-L1), cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), T-cell immunoglobulin, and mucin domain-containing-3 (TIM-3), and lymphocyte-activation gene 3 (LAG-3), are expressed in various activated immune cells, tumor cells, and other tissues, and lead to inhibition of immune responses against tumors [4].