A hypomethylating agent (or demethylating agent[1]) is a drug that inhibits DNA methylation: the modification of DNA nucleotides by addition of a methyl group. Because DNA methylation affects cellular function through successive generations of cells without changing the underlying DNA sequence, treatment with a hypomethylating agent is considered a type of epigenetic therapy.
Currently available hypomethylating agents block the activity of DNA methyltransferase (DNA methyltransferase inhibitors / DNMT inhibitors). Currently two members of the class, azacitidine and decitabine, are FDA-approved for use in the United States in myelodysplastic syndrome and are being investigated for use in a number of tumors.[2]