GNE-049 is a highly potent and selective inhibitor of CBP (IC50: 1.1 nM in TR-FRET assay), and also inhibits BRET and BRD4(1) with IC50 values of 12 nM and 4200 nM, respectively.

CBP:1.1 nM, BRET:12 nM, BRD41:4200 nM

GNE-049 inhibits the expression of MYC (EC50: 14 nM). GNE-049 has excellent potency in the BRET cellular assay and, in an orthogonal measure of the target engagement. GNE-049 is selected for further profiling as it has the best balance of liver microsomes (LM) stability, selectivity, and cellular potency.

GNE-049 shows acceptable PK in mouse, rat, dog, and monkey. GNE-049 is further evaluated in a rat single dose (30-250 mg/kg QD) toxicokinetic study. GNE-049 is selective for CBP/P300 and, importantly, quite selective (3820-fold) over BRD4(1), which revealed from the Determination of potency versus a selection of bromodomains. Furthermore, at the 250 mg/kg dose level, the ratio of the unbound drug concentration in the brain to unbound drug concentration in plasma (Kp,uu) 3 h post-dose is determined to be 0.43, indicating that GNE-049 is penetrating into the CNS and potentially resulting in the observed toxicity.