Project description:To identify genes that are modulated by BET inhibitors in blood, we determined global gene expression changes in ABBV-075-treated mouse whole blood samples
Project description:To identify genes that are modulated by BET inhibitors in blood, we determined global gene expression changes in ABBV-075-treated human PBMC samples
Project description:Competitive inhibitors of acetyl-lysine binding to the bromodomains of the BET (bromodomain and extra terminal) family are being developed for the treatment of solid and heme malignancies. BET family member BRD4 function at enhancers/super-enhancers has been shown to sustain signal-dependent or pathogenic gene expression programs. Here we tested the hypothesis that the transcription factor drivers of castration-resistant prostate cancer (CRPC) clinical progression, including the Androgen Receptor (AR), are critically dependent on BRD4 and thus represent a sensitive solid tumor indication for the BET inhibitor ABBV-075. DHT-stimulated transcription of AR target genes was inhibited by ABBV-075 without significant effect on AR protein expression. Further, ABBV-075 disrupted DHT-stimulated recruitment of BET family member BRD4 to gene regulatory regions co-occupied by AR, including the well-established PSA and TMPRSS2 enhancers. Persistent BET inhibition disrupted the composition and function of AR occupied enhancers as measured by a reduction in AR and H3K27Ac ChIP signal and inhibition of eRNA transcription. ABBV-075 displayed potent anti-proliferative activity in multiple models of resistance to second generation anti-androgens and inhibited the activity of AR-V7 and the AR LBD gain-of-function mutations, F877L and L702H. ABBV-075 was also a potent inhibitor of MYC and the TMPRSS2-ETS fusion protein, important parallel transcription factor drivers of CRPC.
Project description:We comprehensively analyzed the differentially expressed mRNAs (DEmRNAs) and lncRNAs (DElncRNAs) underlying the antitumor functions of BET inhibitors of human HCC cells using RNA sequencing (RNA-Seq). The pan-BET inhibitor ABBV-075 and BD2 specific inhibitor ABBV-744 attenuates the IFNγ-induced inflammatory response. In addition, BD2 inhibitors were predominantly effective in inflammatory response.
Project description:Dual bromodomain BET inhibitors (DbBi) that bind with similar affinities to the first and second bromodomains across BRD2, BRD3, BRD4 and BRDt only displayed modest activity as monotherapy in clinical trials. Thrombocytopenia, closely followed by symptoms characteristic of GI toxicity, have presented as dose limiting adverse events that may prevented escalation to higher dose levels for more robust efficacy. ABBV-744 is a highly selective inhibitor for the second bromodomain (BD2) of the four BET family proteins. In contrast to the broad antiproliferative activities observed with DbBi, ABBV-744 displayed significant antiproliferative activities largely but not exclusively in cancer cell lines derived from AML and androgen receptor (AR) positive prostate cancer. Studies in AML xenograft models demonstrated anti-tumor efficacy for ABBV-744 that was comparable to the pan-BET inhibitor ABBV-075 but with improved tolerability. Enhanced anti-tumor efficacy was also observed with the combination of ABBV-744 and the Bcl-2 inhibitor, venetoclax (ABT-199) compared to monotherapies of either agent alone. These results collectively support the clinical evaluation of ABBV-744 in AML (Clinical Trials.gov identifier: NCT03360006).
