We further found that the infiltration of CD8 + T cells was significantly reduced in CML samples, which means that the immune system could not produce enough killing to CML cells, and the high expression of immune checkpoints PD-1, PD-L1, and CTLA4 in CML samples promoted the immune escape of CML cells. The gene discussed is CTLA4; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.