Panobinostat, a non-selective HDAC inhibitor, has been examined for its tumor suppressor effect against certain cancers and is currently under investigation in clinical trials for several cancers, such as cutaneous T-cell lymphoma, Hodgkin’s lymphoma, prostate cancer, thyroid cancer, and other solid and hematological malignancies [31,32,33]. Here, HDAC9 is linked to prostate cancer.