HDAC9 and peripheral T-cell lymphoma, not otherwise specified: Tucidinostat, an oral HDAC inhibitor belonging to the benzamide class and having specificity for HDAC1, HDAC2, HDAC3, and HDAC10 subtypes, has been approved for the treatment of relapsed or refractory peripheral T cell lymphoma and is under clinical development globally for various other neoplastic and non-neoplastic diseases [25–29].