Immune checkpoint inhibitors: The application of immune checkpoint inhibitors in hematological malignancies mainly includes CD137 antibody, programmed cell death protein-1 (PD-1) antibody, or cytolytic T lymphocyte-associated antigen (CTLA)-4 antibody, and their effect can be verified in humanized mouse models, with either single therapy or combined therapy for different types of tumors. This evidence concerns the gene PDCD1 and hematologic disorder.