BETting on next-generation bromodomain inhibitors

Within the last decade, bromodomain and extraterminal (BET) domain inhibitors were introduced as the first in a wave of new agents known as bromodomain inhibitors. These original examples exhibited anti-inflammatory and anticancer properties, and some have progressed to human clinical trials. BET proteins and their conserved N-terminal bromodomains, BD1 and BD2, have been implicated in the regulation of transcription. The early-generation BET inhibitors showed equal affinity for BD1 and BD2, and therefore the differential roles of BD1 and BD2 remain poorly understood. A recent study published in Science by Gilan et al. outlines the transcriptional and phenotypic effects of inhibiting BD1 and BD2 individually, specifically in the context of cancer and immunoinflammatory pathologies. These findings suggest that BD1 and BD2 have separate and distinct roles in transcriptional regulation, and that BD1- and BD2-selective agents may exhibit higher clinical efficacies in solid tumors, such as prostate cancer, with fewer off-target side effects seen with early generation compounds.