Survival and changes of PB of V617F-TG mice treated with R723. (A) Kaplan-Meier plot of WT mice treated with vehicle (WT-vehicle) and V617F-TG mice treated with vehicle (TG-vehicle), 35 mg/kg of R723 (TG-35mg/kg), or 70 mg/kg of R723 (TG-70mg/kg) for 16 weeks. There was a statistical difference in survival between the TG-vehicle group and the WT-vehicle group (†P < .01) and between the TG-70mg/kg group and the TG-vehicle group (*P < .05 by log-rank test). (B) Differential blood counts in WT-vehicle and TG-vehicle, TG-35mg/kg, or TG-70mg/kg treated with R723 for 6 weeks. V617F-TG mice showed severe leukocytosis and thrombocytosis at 12 weeks of age compared with age-matched WT mice (†P < .01). The leukocyte and platelet count in V617F-TG mice treated with R723 was significantly reduced compared with the TG-vehicle group (**P < .01). V617F-TG mice had anemia (†P < .01) that was not improved by R723 treatment. Data are presented as means ± SE. (C) Hematopoietic compartment of PB assessed by flow cytometry. At 18 weeks of age in the TG-vehicle group, the Mac-1/Gr-1⁺ myeloid cells were significantly increased in number and the B220⁺ B cells and CD3⁺ T cells were increased to a lesser extent than myeloid cells. R723 treatment for 6 weeks significantly decreased the number of Mac-1/Gr-1⁺ myeloid cells (P < .01) and mildly decreased the number of B220⁺ B cells and CD3⁺ T cells (P < .05). Data are means of 6 mice in each group.