Entinostat is a synthetic benzamide derivative that inhibited partially purified human histone deacetylase (HDA) with an IC50 of 2 µM and induced hyperacetylation of nuclear histones in tumor cell lines.  Entinostat inhibited the proliferation of various human tumor cell lines such as A2780, Calu-3, HL-60, and K562 (IC50 values were 0.0415 µM, 0.195 µM, 0.212 µM, and 0.589 µM, respectively).  Entinostat also inhibited the growth of human tumor xenografts in nude mouse.  Saito, A., et al.  "A synthetic inhibitor of histone deacetylase, MS-27-275, with marked in vivo antitumor activity against human tumors."

Entinostat inhibited the proliferation of human breast cancer cells by inducing the expression of transforming growth factor (TGF)-β type II receptor (TβRII) mRNA, but not TGF-beta type I receptor mRNA.  Lee, B.I., et al.  "MS-275, a histone deacetylase inhibitor, selectively induces transforming growth factor beta type II receptor expression in human breast cancer cells.

1. Saito A, et al. Proc Natl Acad Sci U S A, 1999, 96(8), 4592-4597.

2.Sugawara T, et al. 95th AACR, Orlando, 2004, Abst#2451