Mocetinostat (MGCD0103)S1122

MGCD0103 inhibits only a subset of the nine human recombinant HDACs, including HDAC1, HDAC2, HDAC3, and HDAC11 at nanomolar or low micromolar concentrations, in a dose-dependent manner. MGCD0103 reveals most potent inhibitory activity against human HDAC1 and HDAC2 enzymes in vitro, and it does not inhibit class II HDACs. The exocyclic amino group in MGCD0103 is necessary for enzyme inhibitory activity because HDAC-inhibitory activity against HDAC1 and HDAC2 is completely abolished with the desamino analogue. The inhibitory activity of MGCD0103 reaches the maximum plateau at 6 μM, and the maximal inhibitable enzyme pool affected by MGCD0103 is 75% of the total enzyme activity in HCT116 cells whereas NVP-LAQ824 inhibits almost 100% of that in these cells. In A549 cells, MGCD0103 also exhibits dose-dependent inhibition of HDAC activity in whole cells. ^[1]