The expression of PARP1 is upregulated in BCR/ABL+ cells as part of a non-homologous end joining DNA repair pathway (ALT NHEJ) and can serve as biomarker to identify a subgroup of CML patients who may be candidates for therapies that target the ALT NHEJ pathway when treatment with TKIs has failed.36 Here, PARP1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.