Histone deacetylase inhibitors 

Histone deacetylase (HDAC) inhibitors are a group of agents that inhibit the histone deactylase enzymes. During gene expression DNA coils and uncoils around histones. Histone acetylases, acetylate the lysine residues in core histones and histone deactylases remove the acetyl groups from the lysine residues. These actions are important in the regulation of gene expression.

Histone deacetylase inhibitors prevent the deactylation, affect gene expression and causes apoptosis of tumor cells. Histone deacetylase inhibitors are used to treat cutaneous T-cell lymphoma.