BCR and chronic myelogenous leukemia, BCR-ABL1 positive: Based on in vitro data in the K562 cell line and CML primary cells from patients, arsenic can directly induce cell apoptosis and degrade BCR::ABL1 rather than inhibiting BCR::ABL1 activity as would a TKI (Li et al. 2002; Yin et al. 2004; Mao et al. 2010).