Compounds 65 and 66 (Figure 12) displayed high potency of inhibition on HDAC8 (IC50 = 340 ± 26 and 60 ± 10 nM, respectively) compared to HDAC6/11 and were tested on various human tumour cell lines, confirming their antiproliferative activity, which resulted from the disruption of microtubule organization and the cell cycle arrest of tumour cells at the G2/M phase. The gene discussed is HDAC6; the disease is neoplasm.