CD274 and chronic myelogenous leukemia, BCR-ABL1 positive: Thus, in a setting of high leukemic cell load in CP CML patients at diagnosis, CML cells can evade host immune surveillance by activation of the immune checkpoint receptor PD-1 and via PD-L1 upregulation, this signaling pathway influences immune suppression and disease progression, further supported by the recruitment of immunosuppressive MDSC and Treg cell populations (28).