HDAC9 and cancer: MPT0E028 (3-(1-Benzenesulfonyl-2,3-dihydro-1H-indol-5-yl)-N-hydroxy-acrylamide) is a novel HDAC inhibitor in vitro and in vivo with a potent and broad HDAC inhibitory effect in multiple human cancers, both alone and in combination with other treatments [12-14].