Mocetinostat

An isotype-selective small molecule HDAC inhibitor that selectively inhibits HDAC1 (IC50=0.15 uM) ; also inhibits HDAC2/3/11; no effect on HDAC4/5/6/7/8; induces hyperacetylation of histones and caused cell cycle blockade in various human cancer cell lines; inhibits growth of human tumor xenografts in nude mice; orally bioactive.Blood Cancer Phase 2 Clinical (In Vitro) :Mocetinostat is a potent, orally active and isotype-selective HDAC (Class I/IV) inhibitor with IC50s of 0.15, 0.29, 1.66 and 0.59 μM for HDAC1, HDAC2, HDAC3 and HDAC11, respectively. Mocetinostat shows no inhibition on HDAC4, HDAC5, HDAC6, HDAC7, or HDAC8. Mocetinostat (MGCD0103) exhibits potent and selective antiproliferative activities against a broad spectrum of human cancer cell lines in vitro, and HDAC inhibitory activity is required for these effects. In all cell lines tested, Mocetinostat (MGCD0103) partially inhibits cellular HDAC enzyme activity although the maximal inhibition of activity varies among cell lines from 75% to 85% of total activity. The IC50 of Mocetinostat in intact cancer cells is independent of tissue origin. In A549 cells, MGCD0103 shows dose-dependent inhibition of HDAC activity in whole cells. At high concentrations in A549 cells, Mocetinostat inhibits a maximum of 80% of total activity. In HCT116 cells, Mocetinostat induces a significant S-phase depletion and both G1 and G2-M accumulation. (In Vivo) :Mocetinostat (MGCD0103) significantly inhibits growth of human tumor xenografts in nude mice in a dose-dependent manner and the antitumor activity correlated with induction of histone acetylation in tumors. The p.o. administration of Mocetinostat (MGCD0103) (2HBr salt) significantly reduces growth of implanted advanced A549 tumors in nude mice in a dose-dependent manner after 13 days of daily administration. Mocetinostat (170 mg/kg for 2HBr salt, corresponding to 120 mg/kg of free base) significantly blocks growth of tumors compared with vehicle treatment alone (P<0.05 in post-ANOVA Dunnett's test) with no change in body weight.