EAPB0503 prolongs survival and attenuates AML pathological features in NPM1c AML xenograft NSG mice. (A) Eight-week-old NSG mice were injected with 3 million OCI-AML2 or OCI-AML3 cells intravenously (12 mice per cell line per condition). After 1 week post injection, EAPB0503 (2.5 mg/kg, 50 µg/mouse) was intraperitoneally administered every other day, for a total period of 3 weeks. At the end of week 3, one group of six mice per condition was monitored for survival. The remaining six mice per condition were sacrificed for gross pathology, histopathology and hCD45 staining on the flushed bone marrow cells. (B) Kaplan–Meier overall survival of untreated NSG mice injected with OCI-AML2 or OCI-AML3 (n = 6, black line and gray line, respectively) or treated with EAPB0503 (n = 6, blue line and red line, respectively). The t-test was performed to validate significance. P-values less than 0.05 were considered significant. (C) Gross pathology of livers from three representative untreated (upper panel) or EAPB0503-treated (lower panel) OCI-AML3 xenograft mice. (D) Histological analysis (H&E stain) of the liver of a representative untreated (upper panel) or EAPB0503 treated (lower panel) OCI-AML3 xenograft mouse (left panel, magnification 10×, right panel, magnification 40×). (E) Graph showing the hCD45 PerCP percentage in untreated or in EAPB0503 treated xenograft mice injected with OCI-AML3 or OCI-AML2 (n = 6 per condition). (F) Western blot of NPM1c in BM cells extracted from NSG mice xenografted with OCI-AML3 (three representative mice out of six are shown), after in vivo treatment with EAPB0503. Histogram shows the average densitometry of NPM1c/Actin of the 3 representative mice. The t-test was performed to validate significance. ** and *** indicate p values ≤ 0.05; 0.01 and 0.001, respectively. p-values less than 0.05 were considered significant.