| References: |
CPI-637 is a potent and selective CBP/EP300 bromodomains inhibitor with IC50 of 0.03±0.01μM and 11.0±0.6 μM for CBP/EP300 and BRD4, respectively. IC50:0.03±0.01μM (CBP/EP300) IC50:11.0±0.6 μM(BRD4) CPI-637, which demonstrated substantial biochemical potency that was confirmed by isothermal titration calorimetry. A cocrystal structure of CPI-637 in the CBP bromodomain indicated that the compound recapitulated the key hydrogen bonding interactions observed with the parent compound, with the substituted indazole filling space above Pro1110 and the Pro/Arg cleft . As expected, CPI-637 was also potent against EP300, and its opposite enantiomer displayed a >200-fold loss in potency. The biochemical potency of CPI-637 translated well into cells (CBP BRET EC50 = 0.3 μM), and the compound demonstrated a >700-fold selectivity over the BET family of bromodomains (BRD4 IC50 = 11.0 ± 0.6 μM).CPI-637 was also highly selective against other bromodomains (detailed list in the Supporting Information), displaying substantial biochemical activity only against BRD9, which is acceptable, since inhibition of the BRD9 bromodomain has not been shown to produce a pronounced cellular phenotype . In a cellular assay, CPI-637 inhibits the expression of MYC, a transcription factor widely expressed in human cancer,with an EC50 of 0.60 μM, providing an orthogonal measure of the target engagement of the compound .The inactive enantiomer of CPI-637 displayed an EC50 in the same assay of >10 μM. |
