mivebresib (ABBV 075)

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.

The GI50 of K-256 in SU-DHL4 and SU-DHL6 was 12.8 nM and 7.50 nM, respectively, and K-256 induced cell death at lower concentrations than existing drugs (vs. JQ1, OTX-015, and ABBV-075, p < 0.0001; vs. dBET6 and ARV-771, p < 0.01)...As expected, the combination of K-256 with venetoclax also demonstrated synergistic effects in PDX cells, similar to those observed in cell lines (CI of 0.515 to 0.762 for inhibiting cell proliferation; 0.085 to 0.995 for inducing apoptosis)... The novel BET degrader, K-256, bound to BET proteins at lower concentrations than existing BET inhibitors and degraders, strongly suppressing MYC expression, primarily via BRD4 degradation. Additionally, K-256 demonstrated superior therapeutic effects in MYC/BCL2-related PDX models both in vitro and in vivo, suggesting that this novel drug could be a promising therapeutic agent for MYC/BCL2-related lymphoma. Its translation to future clinical applications warrants further consideration.

This was consistent with previous reports that BET inhibitors (e.g., OTX015, mivebresib or ABBV-075 and JQ1) are effective against 3q26.2-r AML cell lines, patient-derived (PD) AML cells and PDX models...In follow-up experiments, XIAP/cIAPs inhibitors birinapant (10-1000 nM) or SM-164 (30-1000 nM), chosen based on the MIPE screen outcomes, induced significantly more dose-dependent apoptosis in 3q26.2-r versus the other AML cell lines...Treatment with the dual mTOR/PIK3CA inhibitor NVP-BGT226 (1-30 nM) or navitoclax or Bcl-xL-specific BH3 mimetic A-1155463 also exerted lethality and synergistically induced apoptosis with mivebresib in AML cells with inv3/t(3; 3)...Co-treatment with birinapant and tegavivint also synergistically induced apoptosis in 3q26.2-r AML cells...Additionally, compared to each drug or vehicle control, co-treatment with birinapant and the BETi OTX015 (30 mg/kg/day, by oral gavage) was more effective in reducing AML burden in the xenograft model. These findings demonstrate promising preclinical activity of IAP protein inhibition against the cellular models of AML with inv3/t(3; 3) with EVI1 overexpression, supporting the rationale to further evaluate in vivo efficacy of birinapant and/or BETi-based combinations against this AML sub-type.

We reveal a novel, druggable neuroblastoma oncogene circuit settling on strong, transcriptional/post-transcriptional synergy of MYCN and IGF2BP1. MYCN/IGF2BP1 feedforward regulation promotes an oncogene storm harboring high therapeutic potential for combined, targeted inhibition of IGF2BP1, MYCN expression and MYCN/IGF2BP1-effectors like BIRC5.

Herein, we modified BRD4i ABBV-075 with a coumarin ring and synthesized a novel series of coumarin derivatives as BRD4 inhibitors...Moreover, compound 27d also exhibited good in vivo and in vitro metabolic stability. All the findings meaningfully make it as a promising lead compound for further drug development.

To investigate the mechanisms of acquired resistance to BET inhibitor (BETi)s, we generated a series of drug resistant sublines by exposing non-small cell lung cancer (NSCLC) NCI-H1975 cells to the BETi ABBV-075...Through combined treatments with BETis and BCL-2 inhibitors (BCL-2is), we demonstrated that BCL-2is synergistically sensitized the resistant cells to BETis. Implications: Based on these results, for the first time, we establish a causal link from VOPP1 loss to BCL-2 gain and then to BETi resistance, which provides new insights into BETi resistance and paves the way for further testing to circumvent BETi resistance.

In addition, knockdown of Bim also inhibited the cell death induced by mivebresib/PZ703b in bladder cancer cells. In summary, our findings reveal that the combination treatment of mivebresib and PZ703b represents a novel promising strategy to treat bladder cancer.

Functional Assays : RNA interference and inhibitors that selectively target GLS (CB-839), DHODH (Teriflunomide, Leflunomide, Vidofludimus, Brequinar and BAY 2402234) or BRD4 (MZ-1; JQ1; AZD5153; Mivebresib and Birabresib) potently and specifically diminish the clonogenic potential of several SCCHN cell lines. However, none of these treatments induce comparable apoptosis in the ex vivo SCCHN tumour tissue. Conclusion The challenges presented by the tumour microenvironment in diminishing the potential of several promising therapies will have to be characterised further, which is the primary focus of our current studies.

The management of unfit and older patients with acute myeloid leukemia should be personalized and be the result of evaluating patient- and disease-specific factors that are essential to their care. Combinations that include venetoclax are an increasingly well-documented option for many of them.

Our findings indicate a previously unrecognized role for BETi in selectively targeting CCR2 TAMs and enhancing the efficacy of AVA therapy in ovarian 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 an improved therapeutic index. Enhanced anti-tumor efficacy was also observed with the combination of ABBV-744 and the BCL-2 inhibitor, venetoclax compared to monotherapies of either agent alone. These results collectively support the clinical evaluation of ABBV-744 in AML (Clinical Trials.gov identifier: NCT03360006).

Conclusively, the design of highly potent therapeutics could be facilitated by the incorporation of pharmacologically active small molecule fragments into the scaffold of existing drugs.

Also, BET bromodomain inhibitors, JQ1 and mivebresib, decreased SAA1 expression and tumor-promoting effects in CAFs, suggesting SAA1 upregulation by enhancer activation in CAFs. Our present data showed that SAA1 is a candidate therapeutic target from gastric CAFs and indicated that increased enhancer acetylation is important for its overexpression.

Confidence intervals will be derived from the Clopper Pearson method. First dosing is planned for Q4 2020.

Venetoclax (Ven) is a selective, small-molecule inhibitor of BCL-2 that exhibits clinical activity in MM cells, particularly in patients harboring the t(11;14) translocation. Navitoclax (Nav) is a small-molecule that targets multiple antiapoptotic BCL-2 family proteins, including BCL-XL, BCL-2, and BCL-W to initiate the intrinsic apoptotic pathway. Eftozanermin alfa (Eftoza) is a novel, second generation TRAIL receptor agonist that induces cell death via death receptor pathways and is under investigation in multiple solid and heme malignancies. In addition, the pan-BET inhibitor mivebresib (Miv) and the BDII selective BET inhibitor ABBV-744 have shown synergistic activity with Ven in cell line models of multiple heme malignancies. Results reported here describe ex vivo drug sensitivities and functional genomic analyses of Ven, Nav, Eftoza, Miv, and ABBV-744 alone or in combination with standard-of-care agents, including bortezomib, carfilzomib, panobinostat, daratumumab, or pomalidomide... An ex vivo functional genomic screen of MM patient specimens demonstrated the usefulness of this approach to identify candidate drugs and potential predictive biomarkers for continued evaluation in clinical trials. This approach confirmed known mechanisms of drug sensitivity and identified new ones, including a novel characterized immune-mediated synergy between Ven and daratumumab, and potential combination strategy for Eftoza and proteasome inhibitors.

Analyses of RNA expression and chromatin immunoprecipitation followed by sequencing revealed that ABBV-744 displaced BRD4 from AR-containing super-enhancers and inhibited AR-dependent transcription, with less impact on global transcription compared with ABBV-075. These results underscore the potential value of selectively targeting the BD2 domain of BET family proteins for cancer therapy.