Crenolanib activity against Ba/F3 cells expressing various FLT3 mutants in vitro and in vivo. (A-B) Ba/F3 cells expressing FLT3 mutants were treated with DMSO or increasing concentrations of crenolanib (A) for 72 hours and viability was measured or (B) for 1 hour and lysed. Western blot analysis was performed on FLT3 immunoprecipitation eluent by use of the indicated antibodies. Cell viability measurements represent the mean ± SEM of 2 to 4 experiments with 6 replicates each (n = 12-24). (C-D) Male NSG mice engrafted with Ba/F3 FLT3-ITD/D835H-luc cells were treated with vehicle, crenolanib 15 mg/kg intraperitoneally twice daily, or sorafenib 15 mg/kg orally once daily for 10 consecutive days beginning on day 1 (5 mice per treatment group). (C) Ba/F3 FLT3-ITD/D835H-luc cell bone marrow infiltration was monitored by noninvasive luciferase imaging. Black bar denotes treatment period (*P = .0157; **P = .0013). (D) Representative whole-body luciferase images from each treatment group are shown.