To further investigate the leukemia inhibitory effect of CAD204520, we treated CRISPR/Cas9 MLL-AF4 and MLL-AF9 cells, as well as MLLr patient primary cells, for 72 h with different CAD204520 concentrations and assessed the dose-dependent inhibition of proliferation revealed with trypan blue staining and microscopy (Figure 4A). This evidence concerns the gene AFF1 and leukemia.