In addition, the specific switch-off of MEIS1 in MLL-r leukemia upon treatment with the menin/MLL interaction surface inhibitor VTP50469 [77] (see below) has demonstrated for the first time that HOXA9 downregulation may be dispensable for the regression of leukemia, i.e., that MEIS1 represents the ideal target. This evidence concerns the gene KMT2A and leukemia.