CPI-637 is an inhibitor of cyclic-AMP response element binding protein (CBP) and adenoviral E1A binding protein of 300 kDa (EP300), a homologous pair of bromodomain-containing proteins (IC50s = 30 and 51 nM in a time-resolved-FRET (TR-FRET) assay). It is selective for CBP and EP300 over the BET family of bromodomains (IC50s = >10 μM), however, CPI-637 is active at bromodomain BRD9 (IC50 = 0.73 μM). CPI-637 also inhibits MYC expression (EC50 = 0.6 μM) in AMO-1 cells.
previous study found that cpi-637 was potent against ep300, and its opposite enantiomer showed a over 200-fold loss in potency. moreover, the biochemical potency of cpi-637 translated well into cells with cbp bret ec50 of 0.3 μm, and cpi-637 demonstrated a more than 700-fold selectivity over the bet family of bromodomains. in addition, cpi-637 was also highly selective against other bromodomains, showing substantial biochemical activity only against brd9. furthermore, it was found that cpi-637 was able to inhibit the expression of myc with an ec50 of 0.60 μm in a cellular assay,. [1].
0.03 and 11.0 μm for cbp/ep300 and brd4, respectively.
[1] taylor, a. m. et al. fragment-based discovery of a selective and cell-active benzodiazepinone cbp/ep300 bromodomain inhibitor (cpi-637). acs medicinal chemistry letters 7, 531-536, doi:10.1021/acsmedchemlett.6b00075 (2016).
