Design, synthesis and biological evaluation of 7-methylimidazo[1,5-a]pyrazin-8(7H)-one derivatives as BRD4 inhibitors.

BRD4 is an attractive target for antitumor due to its important role in regulation of gene transcription. In this paper, we synthesized a series of 7-methylimidazo[1,5-a]pyrazin-8(7H)-one derivatives as potent BRD4 inhibitors and evaluated their BRD4 inhibitory activities in vitro and anti-proliferation effects on tumor cells. Gratifyingly, compound 10j exhibited robust potency of BRD4(1) and BRD4(2) inhibition with IC50 values of 130 and 76nM respectively. Docking studies were performed to explain the structure-activity relationship. Furthermore, compound 10j potently inhibited cell proliferation in BRD4-sensitive cell lines HL-60 and MV4-11 with IC50 value of 0.57 and 0.18μM respectively. Activity on BRD4-independent K562 cell was weaker than on BRD4-sensitive lines. Overall, these results suggest that compound 10j is a potential BRD4 inhibitor deserving further investigation for cancer treatment.