BRD4 BD2 Inhibitors B6(Ocean University of China)

Bromodomain-containing protein 4 (BRD4) has been identified as a promising target in drug discovery, and the development of novel specific BRD4 bromodomain inhibitors will benefit anti-inflammatory drug discovery as well as bromodomain function role disclose. Herein, inspired by marine quinazolinone alkaloid penipanoid C, we designed and synthesized a series of quinazolin-4(3H)-ones with diverse linkers between two aromatic ring systems. Among them, compound 25 possessed good in vitro BRD4 inhibitory activities (IC₅₀ = 3.64 μM for BRD4 BD1 and IC₅₀ = 0.12 μM for BRD4 BD2) and anti-inflammatory activity (IC₅₀ = 1.98 μM for NO production assay). Meantime, 25 obviously suppressed the expression of TNF-α and IL-6 in LPS-stimulated Raw 264.7 and THP-1 cells. Notablely, 25 displayed in vivo therapeutic efficacies in an acute inflammation model without obvious cytotoxicity. These findings suggest that 25 is a selective BRD4 BD2 inhibitor which is a promising anti-inflammatory lead compound worthy for further investigation.

Acute myeloid leukemia is the most common type of acute leukemia in adults. The epigenetic molecule BRD4 is a member of the bromodomain and extra-terminal family and plays an important role in the occurrence and development of tumors. BRD4 is essential for oncogene expression, including c-Myc. So, BRD4 inhibition is considered as an effective strategy for the treatment of hematological and solid malignancies. In recent years, several small molecule inhibitors targeting BRD4 have been developed. However, these inhibitors had excessive hematological toxicity due to the lack of specific binding to BD1 and BD2 domains of BRD4, while other inhibitors with high selectivity lose their antitumor efficacy. To balance the relationship between efficacy and safety, we developed EP-0108A, a BRD4 inhibitor with moderate selectivity for the BD2 domain over BD1 domain of BRD4. Our results show that EP-0108A has antitumor effects in MV4-11 and Kasumi-1 cell line-derived xenograft mouse models without significant effects on heart or breathing safe in rats and Beagle dogs. In repeated dose toxicity studies, EP-0108A showed reversible hematological and gastrointestinal toxicity in both rats and dogs. Our findings indicate that EP-0108A has the potential to be a new therapeutic agent for the treatment of cancer.