JAK2 and precursor B-cell acute lymphoblastic leukemia: A novel JAK2 inhibitor, NVP_BVB808 (BVB808), has been used experimentally in mice xenografted with human B-ALL to recover E864K, Y931C, and G935R mutations within the kinase domain of JAK2 that confer resistance to multiple JAK2 enzymatic inhibitors [9].