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 IC50 = 0.94 nM, BRET IC50 = 6.2 nM; BRD4(1) IC50 = 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.
Subject(s)
Antineoplastic Agents/pharmacology , CREB-Binding Protein/antagonists & inhibitors , Pyrazoles/pharmacology , Pyridines/pharmacology , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacokinetics , CREB-Binding Protein/chemistry , Dogs , Female , Forkhead Transcription Factors/genetics , Forkhead Transcription Factors/metabolism , HEK293 Cells , Humans , Macaca fascicularis , Male , Mice , Protein Domains , Proto-Oncogene Proteins c-myc/genetics , Proto-Oncogene Proteins c-myc/metabolism , Pyrazoles/chemical synthesis , Pyrazoles/chemistry , Pyrazoles/pharmacokinetics , Pyridines/chemical synthesis , Pyridines/chemistry , Pyridines/pharmacokinetics , RNA/genetics , Rats, Sprague-Dawley , Structure-Activity Relationship , Xenograft Model Antitumor AssaysABSTRACT
The single bromodomain of the closely related transcriptional regulators CBP/EP300 is a target of much recent interest in cancer and immune system regulation. A co-crystal structure of a ligand-efficient screening hit and the CBP bromodomain guided initial design targeting the LPF shelf, ZA loop, and acetylated lysine binding regions. Structure-activity relationship studies allowed us to identify a more potent analogue. Optimization of permeability and microsomal stability and subsequent improvement of mouse hepatocyte stability afforded 59 (GNE-272, TR-FRET IC50 = 0.02 µM, BRET IC50 = 0.41 µM, BRD4(1) IC50 = 13 µM) that retained the best balance of cell potency, selectivity, and in vivo PK. Compound 59 showed a marked antiproliferative effect in hematologic cancer cell lines and modulates MYC expression in vivo that corresponds with antitumor activity in an AML tumor model.
