Correspondingly, the most notable clinical trials that have been performed, and those that are currently underway, utilizing epigenetic therapeutic agents to treat nervous system tumors—primarily gliomas—have focused on studying the effects of HDAC inhibitors alone or in combination with other modalities, such as chemotherapies, biologic therapies, or radiation therapies (reviewed in [184]). Here, HDAC9 is linked to nervous system neoplasm.