R547

R547 is a potent, selective and orally active ATP-competitive CDK inhibitor, with K_is of 2 nM, 3 nM and 1 nM for CDK1/cyclin B, CDK2/cyclin E and CDK4/cyclin D1, respectively^{[1][2][3][4][5]}. In Vitro: R547 effectively inhibits CDK1/cyclin B, CDK2/cyclin E, and CDK4/cyclin D1 (Ki = 1–3 nmol/L) and is inactive (Ki > 5,000 nmol/L) against a panel of >120 unrelated kinases in cell-free assays^[4].
R547 effectively inhibits the proliferation of tumor cell lines independent of multidrug resistant status, histologic type, retinoblastoma protein, or p53 status, with IC₅₀s <0.60 μM^[4].
R547 reduces phosphorylation of the cellular retinoblastoma protein at specific CDK phosphorylation sites at the same concentrations that induced cell cycle arrest^[4].
R547 has anti-proliferative activity in tumor cells independent of p53, retinoblastoma, or MDR status^[4].
R547 blocks tumor cells in G1 plus G2 and induces apoptosis^[4].
R547 induces apoptosis as measured by DNA fragmentation^[4].
R547 inhibits phosphorylation of retinoblastoma protein in humantumor cells^[4].
In Vivo: R547 has significant in vivo efficacy with daily oral and once weekly i.v. dosing^[4].
R547 inhibits phosphorylation of retinoblastoma protein in tumors^[4].