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Volasertib (also known as BI 6727) is a small molecule inhibitor of the PLK1 (polo-like kinase 1) protein being developed by Boehringer Ingelheim for use as an anti-cancer agent. Volasertib is the second in a novel class of drugs called dihydropteridinone derivatives. ==Mechanism of action== Volasertib is a novel small-molecule targeted therapy that blocks cell division by competitively binding to the ATP-binding pocket of the PLK1 protein. PLK1 proteins are found in the nuclei of all dividing cells and control multiple stages of the cell cycle and cell division.〔 〕 〔 〕 〔 〕 The levels of the PLK1 protein are tightly controlled and are raised in normal cells that are dividing. Raised levels of the PLK1 protein are also found in many cancers including; breast, non-small cell lung, colorectal, prostate, pancreatic, papillary thyroid, ovarian, head and neck and Non-Hodgkin’s Lymphoma.〔 〕 〔 〕 〔 〕 〔 〕 〔 〕 〔 〕 Raised levels of PLK1 increase the probability of improper segregation of chromosomes which is a critical stage in the development of many cancers. Raised levels of PLK1 have been associated with a poorer prognosis and overall survival in some cancers〔〔 〕 〔 〕 In addition to its role in cell division, there is evidence that PLK1 also interacts with components of other pathways involved in cancer development including the K-Ras oncogene and the retinoblastoma and p53 tumour suppressors These observations have led to PLK1 being recognised as an important target in the treatment of cancer. Volasertib can be taken either orally or via intravenous infusion, once circulating in the blood stream it is distributed throughout the body, crosses the cell membrane and enters the nucleus of cells where it binds to its target; PLK1. Volasertib inhibits PLK1 preventing its roles in the cell-cycle and cell division which leads to cell arrest and programmed cell death.〔 Volasertib binds to and inhibits PLK1 at nanomolar doses however, it has also been shown to inhibit other PLK family members; PLK2 and PLK3 at higher; micromolar doses. The roles of PLK2 and PLK3 are less well understood; however they are known to be active during the cell cycle and cell division. Volasertib inhibits PLK1 in both cancer and normal cells; however it only causes irreversible inhibition and cell death in cancer cells, because inhibition of PLK1 in cancer cells arrests the cell cycle at a different point to normal, non-cancer cells. In cancer cells PLK1 inhibition results in G2/M cell cycle arrest followed by programmed cell death, however, in normal cells inhibition of PLK1 only causes temporary, reversible G1 and G2 arrest without programmed cell death. This specificity for cancer cells improves the efficacy of the drug and minimizes the drug related toxicity. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Volasertib」の詳細全文を読む スポンサード リンク
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