In HEK293 cells, MI-3 accesses the protein target and effectively inhibits the menin-MLL-AF9 interaction. MI-3 effectively blocks MLL fusion protein-mediated leukemic transformation by downregulating the expression of target genes required for MLL fusion protein oncogenic activity. In human MLL leukemia cell lines harboring different MLL translocations, MI-3 effectively blocks cell proliferation, and induces apoptosis.