Targeting histone methyltransferase and demethylase in acute myeloid leukemia therapy

Acute myeloid leukemia (AML) is a clonal disorder of myeloid progenitors characterized by the acquisition of chromosomal abnormalities, somatic mutations, and epigenetic changes that determine a consistent degree of biological and clinical heterogeneity. Advances in genomic technologies have increasingly shown the complexity and heterogeneity of genetic and epigenetic alterations in AML. Among the genetic alterations occurring in AML, frequent are the genetic alterations at the level of various genes involved in the epigenetic control of the DNA methylome and histone methylome. In fact, genes involved in DNA demethylation (such as DNMT3A, TET2, IDH1, and IDH2) or histone methylation and demethylation (EZH2, MLL, DOT1L) are frequently mutated in primary and secondary AML. Furthermore, some histone demethylases, such as LSD1, are frequently overexpressed in AML. These observations have strongly supported a major role of dysregulated epigenetic regulatory processes in leukemia onset and development. This conclusion was further supported by the observation that mutations in genes encoding epigenetic modifiers, such as DMT3A, ASXL1, TET2, IDH1, and IDH2, are usually acquired early and are present in the founding leukemic clone. These observations have contributed to development of the idea that targeting epigenetic abnormalities could represent a potentially promising strategy for the development of innovative treatments of AML. In this review, we analyze those proteins and their inhibitors that have already reached the first stages of clinical trials in AML, namely the histone methyltransferase DOT1L, the demethylase LSD1, and the MLL-interacting protein menin.