Subsequently, Hanfstein and colleagues reported that BCR-ABL1/ABL1IS levels >1% at 6 months were associated with inferior 5-year OS compared to values <1%, thereby suggesting that BCR-ABL1 transcripts at 6 months predict the response of CML to IM [24]. This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.