– SS-208 (SS208) is a novel potent, selective inhibitor of histone deacetylase 6 (HDAC6) with IC50 of 12 nM, >100-fold selectivity over HDAC1/4/5/7/8/9/11.SS-208 has minimal effects on the viability of murine SM1 melanoma cells in vitro, significantly reduced in vivo tumor growth in a murine SM1 syngeneic melanoma mouse model.