Background: Many laboratories have made intensive efforts to develop potent, selective, and
orally bioavailable HDAC inhibitors (HDACIs). Novel HDACIs are being developed with the objective
of improving potency and selectivity against specific types of cancers or non-cancer diseases.
Objective: This updated patent review is an attempt to compile the work of various researchers of
HDACIs from 2012 to mid 2016, and to enlighten and surprise both newcomers in this field and devoted
Method: According to the literature research and the writers' own research experience in the discovery of
Results: The inhibitors possessing new chemical scaffolds have attracted immense interest because they
have the ability to improve HDAC isoform specificity and pharmaceutical properties. Focus is given to
emerging medicinal chemistry principles and insights into the discovery and development of HDAC inhibitors.
Conclusion: The development of effective HDACIs is shifting from trial-and-error approaches to sophisticated
strategies. Effective profiling technologies will continue to have important utility.