Discovery of 4-chloro-3-(5-(pyridin-3-yl)-1,2,4-oxadiazole-3-yl)benzamides as novel RET kinase inhibitors

A series of novel 4-chloro-benzamides derivatives containing substituted five-membered heteroaryl ring were designed, synthesized and evaluated as RET kinase inhibitors for cancer therapy. Most of compounds exhibited moderate to high potency in ELISA-based kinase assay. In particular, compound I-8 containing 1,2,4-oxadiazole strongly inhibited RET kinase activity both in molecular and cellular level. In turn, I-8 inhibited cell proliferation driven by RET wildtype and gatekeeper mutation. The results implied that 4-chloro-3-(5-(pyridin-3-yl)-1,2,4-oxadiazole-3-yl)benzamides are promising lead compounds as novel RET kinase inhibitor for further investigation.