The emerging epi-drugs for cancer therapy (as a single agent or combined with other drugs/therapies) currently include those targeting chromatin remodelers (e.g., SMARC inhibitors), histone modifiers or readers (e.g., HDAC, HMT, HDM, or BET inhibitors), DNA methylation-related enzymes (e.g., DNMT inhibitors), ncRNAs (e.g., lncRNA or miRNA mimics or antagonists), or RNA-modifying enzymes (e.g., ALKBH5 or FTO inhibitors) [30,32,43,44,53,112,113,114,115]. Here, HDAC9 is linked to cancer.