demonstrated an increased PD-1, PD-L1, PD-L2, and CTLA4 expression in peripheral blood mononuclear cells (PBMCs) from MDS patients under HMA treatment with AZA or AZA plus vorinostat, suggesting that resistance to AZA could be mediated by increased expression of these inhibitory markers [78]. Here, PDCD1 is linked to myelodysplastic syndrome.