Discovery of a novel series of imidazo[1',2':1,6]pyrido[2,3-d]pyrimidin derivatives as potent cyclin-dependent kinase 4/6 inhibitors.

CDK4/6 has been identified as an attractive therapeutic target for treatment of cancer. For unmet clinical needs, a novel class of imidazo [1′,2’:1,6]pyrido [2,3-d]pyrimidin derivatives, which had distinctive triheteroaryl structure, had been discovered as CDK4/6 inhibitors. The compounds 10b and 10c, displayed the low nanomolar range activities on CDK4/6, desirable antiproliferative activities, excellent metabolic properties, and acceptable pharmacokinetic characters. In Colo-205 and U87MG xenograft models, compounds 10b and 10c also showed significant tumor growth inhibitions with controllable toxicities. All data confirmed that imidazo [1′,2’:1,6]pyrido [2,3-d]pyrimidin derivatives 10b and 10c could be promising drug candidates for cancer therapy.