mivebresib (ABBV 075)

Notably, the BET inhibitor mivebresib (ABBV-075) significantly improved survival rates by 50% in a metastatic UM xenograft mouse model and prevented detectable metastases in the bones, spinal cord, and brain...BET and HDAC inhibitors reversed gene expression signatures associated with high metastatic risk and induced a neuron-like phenotype in UM cells. These findings establish BET inhibition as a potent and previously underappreciated vulnerability for metastatic UM.

Consequently, combining BET inhibitors with PARP (Poly (ADP-ribose) polymerase) inhibitors or with ATR inhibitors significantly enhanced anti-proliferative effects in SFT cells. Taken together, this study establishes BET inhibitors Mivebresib and BMS-986158 as promising anti-SFT agents.

Accordingly, we reported that ABBV-744 and RVX-208, which selectively target the BD2 domain, and GNE-987, a specific BRD4 degrader, are the most promising inhibitors. However, ABBV-075, a pan-BETi, also exhibits high efficacy, being effective at low doses. Nevertheless, translating these experimental findings into clinical practice remains difficult because of resistance, toxicity, and inconsistent responses. Future approaches include using biomarkers for patient selection, developing isoform-specific BETi, and designing rational combination therapies to enhance treatment for these aggressive pediatric cancers.

Intriguingly, disrupting CREB5 super-enhancers with ABBV-075 significantly reduces its expression and inhibits H3.3K27M DIPG tumor growth. Combined treatment with ABBV-075 and a BRG1 inhibitor presents a promising therapeutic strategy for clinical translation in H3.3K27M DIPG treatment.

Consequently, combining BET inhibitors with PARP (Poly (ADP-ribose) polymerase) or ATR inhibitors significantly enhanced anti-proliferative effects in SFT cells. Taken together, our study established BET inhibitors Mivebresib and BMS-986158 as promising anti-SFT agents.

RNA sequencing revealed a notable overlap between the genes and pathways affected by HDAC and BET inhibition, including the reversal of gene signatures linked to high metastatic risk and upregulation of genes associated with a neuronal phenotype. Together, we found that UM cells are particularly vulnerable to class I HDAC and BET inhibition, and highlight the BET inhibitor mivebresib as a promising candidate for further clinical evaluation.

Synergistic effects from RKI-1447 and the BET inhibitor, ABBV-075, were confirmed in various neuroblastoma models, including zebrafish...BET inhibitors have shown preclinical efficacy against neuroblastoma, but acquired resistance has limited their therapeutic benefit. We reveal that the combination of ROCK and BET inhibitors offers a promising treatment approach that can potentially mitigate resistance to BET inhibitors and reduce toxicity.

At first, we used a D-galactose (D-gal) and BRD4 inhibitor (Abbv-075) to replicate kidney senescence in vivo...The findings also suggest that BRD4 inhibitors have potential nephrotoxic effects for oncology treatment. BRD4 may be a potential therapeutic biomarker and drug target for aging-related kidney diseases, which warrants additional studies.

Further characterization of genome-wide binding of MYC, MYCN, and MYCL1 uncovered unique enhancer and epigenetic preferences. Implications: Our study suggests that chromatin landscapes could establish cell states with unique gene expression programs, conveying sensitivity to epigenetic inhibitors such as mivebresib.

Additionally, knockdown of SS18-SSX, which upregulates BCL2, reduced the sensitivity to ABBV-075. These findings suggest the potential utility of BET inhibitors targeting the SS18-SSX-regulated intrinsic apoptotic pathway as a promising therapeutic strategy for SS.

As a result, combined treatment of NC tumors with tazemetostat and the BET inhibitor mivebresib produces marked antitumor therapeutic synergy in vitro and in vivo, associated with enhanced suppression of RB1 function through convergent remodeling of NC gene expression. This study advances epigenetic cooperativity as a distinct mode of gene expression dysregulation in NC and nominates a compelling combination epigenetic strategy for investigation in clinical trials for patients. See related article by Huang et al., p. 3956.