JAK2 and chronic myelogenous leukemia, BCR-ABL1 positive: In other studies, Fava and colleagues[17] reported that 3 CML patients with simultaneous JAK2 mutation and BCR-ABL1 fusion only reached suboptimal responses to TKIs, whereas Boddu et al[5] showed that 2 patients with JAK-V617-mutated CML rapidly progressed to a blast crisis after treatment with TKIs.