(A) Treatment with APIO-EE-9 inhibits ESCC PDX tumor size compared with the untreated group. The asterisks (*, **) indicate a significant (p < 0.05, p < 0.01, respectively) decrease in tumor volume in the APIO-EE-9-treated groups compared with the vehicle-treated group. (B) Mouse tumors were photographed (upper) and tumor weight determined (lower). The asterisk (*) indicates a significant (p < 0.05) decrease in tumors from mice treated with APIO-EE-9 compared with the vehicle-treated group. (C) Mouse body weight. (D) Immunohistochemistry (IHC) staining of phosphorylated (p)-histone H3 (Ser10), cleaved caspase 3, and Ki-67. The relative integrated optical density (IOD) value was obtained using the Image-Pro Plus software program. The asterisks (*, **) indicate a significant (p < 0.05, p < 0.01, respectively) decrease in staining in tissues from mice treated with APIO-EE-9 compared with vehicle-treated mice.