Superior efficacy of ruxolitinib combined with dexamethasone in JAK2-rearranged ALL. NSG mice were injected with primary leukemic cells (A) ALL19 or (B) ALL21. When engraftment reached 10¹⁰ p/sec per cm²/steridian on bioluminescent imaging, animals (n = 5) were treated with vehicle, ruxolitinib (provided as chow), dexamethasone (4 mg/mL ad libitum), or ruxolitinib and dexamethasone combined. Treatment length is indicated by the gray shaded area; animals were euthanized at the last time point. Analysis of slope was measured by linear regression and 1-way ANOVA with Tukey posttest for multiple comparisons. Spleen weights were measured at the time of euthanasia. Each point represents the mean ± SD (n = 5). Representative H&E staining of bone marrow and spinal cord of treated mice are shown. *P < .05, **P < .01, ***P < .001, ****P < .0001. Ruxo, ruxolitinib.