LAG3 and cancer: T-cell immunoglobulin and mucin-domain containing-3 (TIM-3), T-cell immunoglobulin and ITIM domain (TIGIT), lymphocyte activation gene-3 (LAG-3), cytotoxic T-lymphocyte antigen 4 (CTLA-4), and Protein-1 (PD-1) are considered to be the major immune CIRs and the most promising immunotherapeutic targets in cancer therapy [172].