Pracinostat, also known as SB939, is an orally bioavailable, small-molecule histone deacetylase (HDAC) inhibitor with potential antineoplastic activity. Pracinostat inhibits HDACs, which may result in the accumulation of highly acetylated histones, followed by the induction of chromatin remodeling; the selective transcription of tumor suppressor genes; the tumor suppressor protein-mediated inhibition of tumor cell division; and, finally, the induction of tumor cell apoptosis. In March 2014, pracinostat has granted Orphan Drug for acute myelocytic leukemia (AML) and for the treatment of T-cell lymphoma by the Food and Drug Administration.