A potent HDAC8 inhibitor (IC50 = 0.01 μM) with >200-fold selectivity over HDAC isoforms 1, 2, 3, 6, and 10 (IC50s = 4, >50, >50, 2.9, and 13 μM, respectively); induces caspase-dependent apoptosis in cell lines derived from T-cell lymphomas or leukemias (GI50s = 2.4 - 4 μM).