Based on previous studies highlighting the promising preclinical efficacy of histone deacetylase (HDAC) inhibitors against KMT2A-r leukemia (8, 9), we here investigated the preclinical efficacy of a novel combination of targeted drugs, CBL0137 and the HDAC inhibitor panobinostat, in KMT2A-r leukemia models. This evidence concerns the gene HDAC9 and leukemia.