Unlike imatinib in CML, where already 6 months of TKI treatment can result in durable clinical response by reduction of the BCR::ABL1 transcript, JAK2 inhibitor short-term treatment does not induce a significant reduction in MPN-driving allele burden (Verstovsek et al., 2010; Pardanani et al., 2015). Here, BCR is linked to chronic myelogenous leukemia, BCR-ABL1 positive.