To evaluate, whether our in vitro data derived from leukemia cell lines and mutant-TK cell line models translate into a clinically meaningful antiproliferative effect in native leukemia cells, we treated an acute leukemia sample taken from a patient suffering from FLT3 mutant-TKD2 positive AML and a sample from a patient with AML tested negative for FLT3 or KIT mutations with varying concentrations of NVP-BGT226 or NVP-BEZ235 and tested for the capacity to inhibit cellular proliferation ex vivo using an XTT-based assay. Here, FLT3 is linked to acute leukemia.