AR-42

AR-42 is a novel HDAC inhibitor with an IC50 of 0.61 μM for acute lymphoblastic leukemia (697) cell lines. In chronic lymphocytic leukemia (CLL) cells, the 48-hr LC50 of AR-42 is 0.76 μM. AR-42 produces dose- and time-dependent acetylation both of histones and tubulin, and induces caspase-dependent apoptosis that is not reduced in the presence of stromal cells. AR-42 significantly reduced leukocyte counts and/or prolonged survival in three separate mouse models of B-cell malignancy without evidence of toxicity. AR-42 has in vitro and in vivo efficacy at tolerable doses. In additon, AR-42 promoted hyperacetylation of H3, H4, and alpha-tubulin, and up-regulation of p21. Down-regulation of Kit occurred after AR-42 爐reatment via inhibition of Kit transcription.