JAK2 and precursor B-cell acute lymphoblastic leukemia: Promising pre-clinical studies showed that CHZ868 not only improved survival and leukaemic burden in vivo models of MPN and B-ALL, but preferentially inhibited JAK2 p. V617F-mutant JAK2 hematopoietic cells over WT JAK2 cells (Meyer et al., 2015; Wu et al., 2015).