Tucidinostat (formerly known as chidamide) is an oral benzamide class of HDAC inhibitor with subtype specificity for inhibition of HDAC1, HDAC2, HDAC3, and HDAC10.16 Basic studies have shown that benzamide subtype-selective HDAC inhibitors, including tucidinostat and entinostat, enhance tumor immune surveillance by activating natural killer cell- and antigen-specific cytotoxic T-cell-mediated cellular antitumor immunity. Here, HDAC9 is linked to neoplasm.