The expression of PD-L1, PD-L2, PD-1, and CTLA-4 was upregulated in a cohort of MDS, CMML, and AML patients treated with epigenetic therapy, suggesting inhibitory immune checkpoint signaling pathways might be involved in hypomethylating agent (HMA) resistance [13]. Here, CTLA4 is linked to acute myeloid leukemia.