Inhibition of β-catenin enhances sorafenib activity in FLT3-ITD PDX cell xenograft NSGS mice and suppresses engraftment potential of the PDX cells. (A) Experimental scheme. After confirmed engraftment by flow cytometry of human CD45 positivity, NSGS mice were treated with RPI-724, sorafenib, and the combination for 4 wk. (B) Leukemia burden assessed by flow cytometry measuring human CD45+ cells in mouse PB after 3-wk treatments. (C) Leukemia burdens in mouse BM and spleen determined by flow cytometry after 25-d treatments. (D) Survival curves. (E) Engraftment of the ex vivo treated PDX cells and survival curve. The PDX cells (2×106) were untreated or treated with C-82 (1 μM), sorafenib, (2.5 μM), or both for 48 h and then injected into NSGS mice. Engraftment was assessed by flow cytometric measurement of human CD45 positivity at 9 and 12 wk post cell injection. Ctrl, control; Sor, sorafenib; Comb, combination. * P<0.05, ** P<0.01.