Discovery of pyrrolo[1,2-a]quinoxalin-4(5H)-one derivatives as novel non-covalent Bruton's tyrosine kinase (BTK) inhibitors

Bruton's tyrosine kinase (BTK) is a promising target in the treatment of B cell malignancies and autoimmune disorders. Developing selective non-covalent BTK inhibitors is an important strategy to overcome the side effects and drug resistance induced by covalent BTK inhibitors. In this article, we designed and synthesized pyrrolo[1,2-a]quinoxalin-4(5H)-one and imidazo[1,2-a]quinoxalin-4(5H)-one based selective noncovalent BTK inhibitors via scaffold hopping from BMS-986142 and investigated their biological activities. Among the synthesized compounds, pyrrolo[1,2-a]quinoxalin-4(5H)-one derivatives 2 and 4 showed great BTK inhibition potency with IC₅₀ value at 7.41 nM and 11.4 nM, respectively. Besides, they showed equivalent or even better potency in U937 and Ramos cells than BMS-986142. The kinase selectivity profiling study illustrated the excellent selectivity of compound 2 against a panel of 468 kinases. In U937 xenograft models, compound 2 could significantly inhibit tumor growth with TGI = 65.61%. In all, we provided a new scaffold as non-covalent selective BTK inhibitors and the representative compounds exhibited potency both in vitro and in vivo.