CTLA4 and myeloid leukemia: The significant differences in clinical outcomes in the two DAC-involved groups might be due to dose-dependent apoptosis in myeloid leukemia cells and synergistic cytotoxicity or chemosensitization (29, 30), especially dose-dependent upregulation of PD-L1, PD-L2, PD-1, and CTLA4 expression (31).