HDAC-IN-79 (compound 4) is an orally active dual xanthine oxidase-HDAC inhibitor ( Xanthine oxidase : IC 50 =6.6 nM; HDAC1 : IC 50 =134 nM; HDAC2 : IC 50 =284 nM; HDAC3 : IC 50 =173 nM; HDAC6 : IC 50 =1.32 nM;), with significant in vivo anti-hyperuricemia and anti-tumor activities. HDAC-IN-79 is the most potent cell growth inhibitor ( IC 50 =0.706 μM) of leukemia HL60 cells, induces apoptosis and autophagy , and can regulate the expression levels of signature biomarkers associated with intracellular HDAC inhibition.