FIGURE 5.

FC531 is well tolerated and confers anti‐leukemic activity against FLT3/ITD⁺ AML cells in PDX models (JAX model J000106134). FC531 demonstrated single agent activity against AML cells in vivo as shown by a significant reduction of leukemic burden after 10 doses. Leukemic burden was assessed via (A) human (h) CD33 positivity per flow cytometry and (B) FLT3/ITD mutant drops as detected per highly sensitive ddPCR. The mean ± SEM is based on replicate experiments (n = 5). Statistically significant changes in the change of leukemic burden are indicated (**p < 0.01; ***p < 0.001). (C) Kaplan Meier analysis depicting the survival of mice treated with a 10‐day course (days 1–5 and 8–12) of single agent Cytarabine, single agent FC531 or Cytarabine (days 1–5) followed by FC531 (days 8–12) (as outlined in Table 3). Only combined therapy resulted in statistically improved survival compared to untreated animals (p = 0.0018). FC531 only treated mice showed a trend towards improved survival (p = 0.1 vs. untreated)