Moreover, while the blockage of HOXA9, an KMT2A downstream target, sensitizes KMT2A‐r leukemia to PARP inhibitors and impairs DDR, the overexpression of HOXA9 rather confers PARP inhibitor resistance to AML1‐ETO and PML‐RARα transformed cells [72]. Here, HOXA9 is linked to leukemia.