Notably, the evaluation of potential toxicities, adverse events and development of resistance induced by the combinatorial treatment based on CAR-T cells and epigenetic drugs targeting CSCs such as DNMT and HDAC inhibitors is currently ongoing in AML, ALL and NHL, although in a very limited number of clinical trials (NCT03612739, NCT04553393, NCT05797948 and NCT05370547). This evidence concerns the gene HDAC9 and acute myeloid leukemia.