hHDAC8 [a] IC50 Furthermore, 9d, the most prominent antiproliferative hit compound from this series, was evaluated in a cell viability assay against two additional solid cancer cell lines. We chose the ovarian cancer cell line A2780 and the malignant glioma cell line U87. The results are shown in Table . 9d showed submicromolar cytotoxic activity against all cancer cell lines except for U87, for which the IC50 was 2.03 µM which is around 3-fold less potent than 9d in Cal27 cells. However, also quisinostat showed around 5.5-fold reduced potency in U87 than in Cal27 cells.