601453 Disclosed is 8-cyclopentyl-7-ethyl-5-methyl-2-(1-phenylethylamino)-7,8-dihydropteridin- 6(5H)-one, represented by formula Ib wherein R1 is phenyl and R8 is ethyl. Also disclosed are compositions thereof, and the use of the compound and compositions in the manufacture of medicaments. The compound is useful as a protein kinase inhibitor of both PLK and PLK1 protein kinases and therefore the compounds, compositions and medicaments disclosed are useful in the treatment of proliferative disorders, neurodegenerative disorders, autoimmune disorders, inflammatory disorders or immunologically mediated disorders and melanoma, myeloma, leukemia, lymphoma, neuroblastoma, colon cancer, breast cancer, gastric cancer, ovarian cancer, cervical cancer, lung cancer, central nervous system cancer, renal cancer, prostate cancer, bladder cancer, or pancreatic cancer.
