As main examples, dual PTK (Protein Kinase) and HDAC inhibitors have been widely developed, namely EGFR (Epidermal Growth Factor Receptor)-HDAC hybrid inhibitors efficient in liver, pancreatic, breast, and lung human cancer cell lines [53], or hybrid BCR/ABL-HDAC inhibitors displaying promising cytotoxicities against various leukemic cell lines [54]. Here, HDAC9 is linked to cancer.