Epigenetic modifications are responsible for heritable changes in gene expression that do not affect the gene itself. Chromatin remodeling, DNA methylation and gene expression regulation by non-coding RNAs are all epigenetic mechanisms. Epigenetic mechanisms of action can serve as valuable targets of drug development. In fact, two DNA methylation inhibitors and two histone deacetylase (HDAC) inhibitors, each for treating cancer, have been approved by the FDA. Currently, only one agent with an epigenetic mechanism of action is in Phase III development, but several are in earlier stage development. The epigenetic mechanisms of action for most of these are HDAC inhibitors, including “second generation” HDAC inhibitors, which selectively target individual HDACs or HDAC classes.

Source: Nature Reviews Drug Discovery