MS645 is a bivalent BET bromodomains (BrD) inhibitor with a Ki of 18.4 nM for BRD4-BD1/BD2. MS645 spatially constrains bivalent inhibition of BRD4 BrDs resulting in a sustained repression of BRD4 transcriptional activity in solid-tumor cells[1].
MS645 has cell growth inhibitory effects on noncancer cell lines of mouse macrophage RAW cells and nontumorigenic breast epithelial MCF10A with IC50s of 4.1 nM, 6.8 nM, 7.9 nM for triple-negative breast cancer (TNBC) cell lines HS5878T, BT549, and MCF 10A[1]. MS645 (15, 30, 60 nM) results in a dramatic reduction of c-Myc expression and an increase of p21, a tumor suppressor and cell-cycle inhibitor in HCC1806 cells[1].
[1]. Ren C, et al. Spatially constrained tandem bromodomain inhibition bolsters sustained repression of BRD4 transcriptional activity for TNBC cell growth.Proc Natl Acad Sci U S A. 2018 Jul 31;115(31):7949-7954.