Wang et al. and Prestipino et al. initiated the first studies on PD-1/PD-L1 in MPN, and their results show that this immune axis could be a relevant therapeutic target for MPN [124,128] because it seems to be triggered by key actors of the disease’s development (oncogenic driving mutations), and it is also involved in immune silencing. This evidence concerns the gene PDCD1 and myeloproliferative neoplasm.