Fig. 4

Sitravatinib is efficient to eliminate FLT3-ITD-F691L cells in vitro and in vivo. A IC50 values of BaF3-FLT3-ITD and BaF3-FLT3-ITD-F691L cells treated with each drug for 48 h. Error bars indicate mean ± standard error, n = 3 independent experiments. B Fold changes of IC50 values of FLT3 inhibitors for BaF3-FLT3-ITD cells with or without secondary TKD mutations. Error bars indicate mean ± standard error, n = 3 independent experiments. C Western blot analysis of p-FLT3, p-STAT5, p-AKT and p-ERK 1/2 in BaF3-FLT3-ITD-F691L cells after treatment with sitravatinib at the indicated concentrations for 4 h. D BALB/c mice were intravenously inoculated with BaF3-FLT3-ITD-F691L cells. From 2 days after the injection, mice were administrated with vehicle, sitravatinib (20 mg/kg/day), gilteritinib (30 mg/kg/day) or quizartinib (10 mg/kg/day) until the first mouse died in the vehicle group. The percentage of leukemia cells in PB of BaF3-FLT3-ITD-F691L-diseased mice on day 10 was detected by flow cytometry (n = 6 mice per group). E The percentage of leukemia cells in BM and SP of BaF3-FLT3-ITD-F691L-diseased mice on day 10 (n = 3 mice per group). F Top: The spleen image and weight of mice in (E); Bottom: One mouse of each group in (E) was randomly selected for the H&E staining of spleens. A normal mouse used as control. Scale bars: 1500 μm. Green arrows: typical spleen lymph nodules; red arrows: fuzzy lymph nodules. G Body weight measurements of the mice during drug administration. H The survival curves of BaF3-FLT3-ITD-F691L-diseased mice treated with vehicle (n = 10), sitravatinib (n = 10), gilteritinib (n = 12) or quizartinib (n = 9). Error bars indicate mean ± standard error, *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001