New and emerging HDAC inhibitors for cancer treatment.

Epigenetic enzymes are often dysregulated in human tumors through mutation, altered expression, or inappropriate recruitment to certain loci. The identification of these enzymes and their partner proteins has driven the rapid development of small-molecule inhibitors that target the cancer epigenome. Herein, we discuss the influence of aberrantly regulated histone deacetylases (HDACs) in tumorigenesis. We examine HDAC inhibitors (HDACis) targeting class I, II, and IV HDACs that are currently under development for use as anticancer agents following the FDA approval of two HDACis, vorinostat and romidepsin.