HDAC inhibitors have already proven their fundamental efficacy against cancer in preclinical and clinical studies, which has led to the FDA approval of vorinostat (SAHA), romidepsin (FK288), panobinostat (LBH589), and belinostat (PXD101) for cancer therapy (Nguyen et al., 2013; Suraweera et al., 2018; Mehndiratta et al., 2020). This evidence concerns the gene HDAC9 and cancer.