KD 5170 is a mercaptoketone-based inhibitor of class I and II histone deacetylases (HDACs; IC50s = 20, 2,060, 75, 26, 950, 14, 85, 2,500, 150, and 18 nM for HDAC1-10, respectively). It exhibits broad spectrum antitumor activity in vitro and in vivo. KD 5170 increases the acetylation of histones and activates caspases 3, 8, and 9, leading to apoptosis in primary myeloma cells.
