Overall, one of the concerns was the loss of a graft-vs.-leukemia effect, given the pharmacological interference with the JAK1/2 signal pathway; however, the reported rate of disease recurrence after Ruxolitinib was of 9.3 and 2.4 % of the patients in the aGVHD and cGVHD groups, respectively. Here, JAK1 is linked to leukemia.