GNE-781, A Highly Advanced Potent and Selective Bromodomain Inhibitor of Cyclic Adenosine Monophosphate Response Element Binding Protein, Binding Protein (CBP)

Abstract

Inhibition of the bromodomain of the transcriptional regulator CBP/P300 is an especially interesting new therapeutic approach in oncology. We recently disclosed in vivo chemical tool 1 (GNE-272) for the bromodomain of CBP that was moderately potent and selective over BRD4(1). In pursuit of a more potent and selective CBP inhibitor, we used structure-based design. Constraining the aniline of 1 into a tetrahydroquinoline motif maintained potency and increased selectivity 2-fold. Structure-activity relationship studies coupled with further structure-based design targeting the LPF shelf, BC loop, and KAc regions allowed us to significantly increase potency and selectivity, resulting in the identification of non-CNS penetrant 19 (GNE-781, TR-FRET IC = 0.94 nM, BRET IC = 6.2 nM; BRD4(1) IC = 5100 nΜ) that maintained good in vivo PK properties in multiple species. Compound 19 displays antitumor activity in an AML tumor model and was also shown to decrease Foxp3 transcript levels in a dose dependent manner.

Enhancer Activity Requires CBP/P300 Bromodomain-Dependent Histone H3K27 Acetylation

“…The Bromodomain of CBP/P300 Contributes to Histone Acetylation Independent of Chromatin Localization As a critical marker of enhancer activity, we wished to probe the role of the bromodomain in CBP/P300 function and H3K27 acetylation, using the highly potent and selective CBP/P300 bromodomain inhibitor GNE-049 (Jin et al, 2017;Romero et al, 2017) ( Figure S1A). Abrogation of bromodomain activity by GNE-049 treatment did not disrupt localization of CBP/P300 to chromatin as assessed by cell fractionation and ChIP-seq (Figures 1A and 1B).…”

“…Cell proliferation was evaluated using CellTiter-Glo reagent (Promega) or by assessment of confluence using the IncuCyte Zoom platform. GNE-049 was synthesized as described (Jin et al, 2017;Romero et al, 2017). CBP30, C646, trichostatin A, doxorubicin, and JQ1 were obtained from Selleckchem.…”

A Chemical Toolbox for the Study of Bromodomains and Epigenetic Signaling

“…An alternative chemical probe is the benzoxazepine I-CBP112 34 . Recently, a highly potent antagonist, GNE-781, which has 650-fold selectivity over BRD4 for CBP/p300 became available 47 .…”

Advancements in the Development of non‐BET Bromodomain Chemical Probes

“…Finally,s witching to a methylu rea acetylated lysine mimetic to introduce an additional H-bond donor,a nd thusd ecrease CNS penetration, resulted in 19. [49] As discussed, 19 displayed excellent potency for CREBBP (pIC 50 = 9.0) and an improved selectivity over the BET family (pIC 50 = 5.3). Additionally, 19 showed selectivity over the non-BET bromodomains (> 5000), as demonstrated by a DiscoverX BROMOscan( 40 bromodomains) panel, as well as against kinase (no inhibition > 10 %a t1mm), CEREP off-target (no inhibition > 39 %a t1 0mm), and cytochrome P450 (no inhibition at 1 mm)p anels.…”

“…Compound 48 demonstrated permeability (Caco-2 cell P app = 163 nm s À1 )a nd was shown to successfully engage BRPF2 (pIC 50 = 6.3) and TAF1(2) (pIC 50 = 6.0) within cells, as measured by NanoBRETa ssay,d espite poor solubility (10 mgmL À1 ). As tructurally similar negative control,B AY-364 (49), was also developed and showed decreased potency at www.chemmedchem.org both BRPF2 (BRPF2 pIC 50 < 4.7) and TAF1 (TAF1 pIC 50 = 4.9). The polypharmacology of 48,h owever,h indersa ssigning anyo bserved phenotype to ap articular bromodomain.B ayer have subsequently published ap atent disclosing an umber of other BRPF1/TAF1 dual inhibitors based around the same dimethylated imidazolidinone core scaffold.…”