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. 2024 Sep 17;38(12):2561–2572. doi: 10.1038/s41375-024-02405-5

Fig. 6. MA49 kills FLT3 mutant AML blasts and cells in vitro and in vivo without an impact on hematopoietic stem cells.

Fig. 6

A, B Serial dilutions of 50 µM top dose of MA49 versus MA72, MA68, sorafenib, and cytarabine were applied to primary ex-vivo samples from leukemia patients with wild-type FLT3 or FLT3-ITD for 72 h. Cell survival is provided as %-values compared to untreated control cells (100% survival) in the MTS-assay. B EC50 values for the data shown in (A) were determined. C Cell viability analysis of murine bone marrow stem cells. Bone marrow was collected from the hind legs of previously killed C57BL/6 mice. The cells were treated with the indicated concentrations of MA49, MA68, or a high concentration of 10% DMSO as a positive control for cytotoxicity for 24 h; Ctrl, untreated. One-way ANOVA statistical test was used to determine statistical significance; ns not significant; *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001; n = 3, male and female. D Bone marrow cells were freshly isolated from C57BL/6 mice and cultured for 7 days in medium containing the inhibitors at 50–100 nM and supplementation with either GM-CSF to induce the differentiation of myeloid progenitor cells to BMDCs or M-CSF to induce the differentiation to BMDMs. After one week, we assessed the total cell number, viability and frequencies of CD11c+ (pan dendritic cell marker) or F4/80+ (macrophage marker) cells, the expression of their activation marker CD86, cell viability (negative for FVD), and the total cell numbers; -, untreated, +, 50 nM, ++ 100 nM; n = 3, male and female. E Waterfall plots demonstrating changes in tumor volume [%] for each individual zebrafish larvae engrafted with AML cells, from baseline (day 1 = start of the treatment) until day 3 after MV4-11 cell injection. Zebrafish larvae xenografts were treated with DMSO used as a solvent (n = 17 larvae; left) or 200 nM MA49 (n = 18 larvae; right) for 48 h; each bar reflects one individual xenograft. Numbers indicate the percentage of early larvae with progressive disease (PD), stable disease (SD) and partial response (PR) in each treatment group on day three.