CD274 and myelodysplastic syndrome: The upregulation of immune checkpoints (e.g., PD-1/PD-L1, CTLA-4, TIM-3, TIGIT, CD47) on T cells in MDS creates an immune-evasive tumor microenvironment, leading to reduced cytotoxicity, impaired NK cell function, and T-cell exhaustion (54, 55).