Our findings were congruent with various other studies demonstrating minimal efficacy of single-agent ruxolitinib in multiple independent JAK2 mutant ALL patient-derived xenograft (PDX) models and the lack of cytotoxicity observed in JAK2 mutant human cell lines performed in short-term in vitro assays (Maude et al. 2012; Tasian et al. 2012; Weigert et al. 2012; Steeghs et al. 2017). Here, JAK2 is linked to acute lymphoblastic leukemia.