Successes and challenges in the development of BD1-selective BET inhibitors: a patent review

Bromodomain and ExtraTerminal (BET) domain proteins are transcriptional cofactors that, recognizing acetylated lysines of histone and non-histone proteins, can modulate gene expression. The BET family consists of four members, each of which contains two bromodomains (BD1 and BD2) able to recognize the acetylated mark. Pan-BET inhibitors (BETi) have shown a promising anticancer potential in many clinical trials; however, their further development has been in part hampered by the side effects due to their lack of selectivity. Mounting evidence suggests that BD1 is primarily involved in cancer and that its selective inhibition can phenocopy the anticancer effects of pan-BETi with increased tolerability. Therefore, the development of BD1 selective inhibitors is highly pursed in both academia and industry.This review aims at giving an overview of the patent literature of BD1-selective BETi between 2014 and 2023. WIPO, USPTO, EPO, and SciFinder® databases were used for the search of patents.The development of BD1-selective BETi, despite challenging, is highly desirable as it could have a great impact on the development of new safer anticancer therapeutics. Several strategies could be applied to discover potent and selective compounds with limited side effects.