Pracinostat is a pan‐HDAC inhibitor and has been evaluated in the phase II clinical stage for various of solid and hematological tumors, including MDS, AML, prostate cancer, and sarcoma (NCT01993641, NCT01912274, NCT01075308, and NCT01112384).566, 567, 568. Here, HDAC9 is linked to myelodysplastic syndrome.