has role antiviral agent renoprotective agent cyclopentanes piperazines piperidines antineoplastic agent aminopyridine pyridopyrimidine secondary amino compound tertiary amino compound aromatic ketone EC 2.7.11.22 (cyclin-dependent kinase) inhibitor palbociclib A member of the class of pyridopyrimidines that is 2-{[5-(piperazin-1-yl)pyridin-2-yl]amino}pyrido[2,3-<em>d</em>]pyrimidin-7-one bearing additional methyl, acetyl and cyclopentyl substituents at positions 5, 6 and 8 respectively. It is used in combination with letrozole for the treatment of metastatic breast cancer. CHEBI:85993