Emerging approaches for histone deacetylase inhibitor drug discovery

Introduction: Histone deacetylases (HDACs) are key players in the mediation of gene expression for both cancerous and noncancerous malignancies. Overexpression of these enzymes has been demonstrated in numerous types of cancer with some enzyme isoforms also involved in neurological, inflammatory and viral pathologies. Hence, the development of HDAC inhibitors (HDACis) represents a promising approach for their treatment. Numerous chemical entities have been studied in the recent years and some of them have reached clinical trials. Areas covered: This review summarizes the recent efforts in the drug development of HDACis and their potential application as therapeutic agents in cancerous, neurological, inflammatory and viral diseases. Expert opinion: The development of novel potent and selective HDACis is ongoing. However, increased scientific effort is needed to aid the fight of specific types of cancerous or noncancerous disease with more selective agents required to avoid side effects during therapy. An interesting therapeutic approach is the use of HDACis in combination with other epigenetic target modulators to combine their therapeutic potential for a synergistic effect.