This compound potently inhibits the expression of MLL-fusion target genes HOXA9 and MEIS1, selectively inhibits the proliferation of MLL-rearranged leukemia cells (IC50 = 3.5 nM), and causes complete and sustained regression in a rat xenograft model of MLL-rearranged leukemia. The gene discussed is HOXA9; the disease is leukemia.