PDCD1 and acute myeloid leukemia: Increased expression of the inhibitory ligands for T-cell–regulating checkpoints such as CTLA-4, PD-1, B7-H3 and T cell immunoglobulin and mucin-domain containing-3 (TIM-3) was reported in AML and was associated with T cell exhaustion and poor prognosis (62, 63, 73).