BCR and chronic myelogenous leukemia, BCR-ABL1 positive: Promising results for several checkpoint inhibitors have been reported in various cancers including melanoma, lung cancer and Hodgkin lymphoma.25, 26, 27, 28 In these malignancies, somatic mutations resulting in amino acid changes give rise to new epitopes recognized by CTLs, called neoantigens.29, 30 However, the BCR-ABL1 driver mutation alone can cause leukemia, and non-driver mutations are limited in CML.31 Thus, checkpoint inhibitors alone may not be sufficient to evoke effective immunity against CML-LSCs.