Volasertib (BI 6727)S2235

Like BI2536, BI6727 is an ATP-competitive kinase inhibitor from the dihydropteridinone class of compounds. In addition to Plk1, BI6727 also potently inhibits two closely related kinases Plk2 and Plk3 with IC50 of 5 nM and 56 nM, respectively. BI6727 at concentrations up to 10 μM displays no inhibitory activity against a panel of >50 other kinases. BI6727 inhibits the proliferation of multiple cell lines derived from various cancer tissues, including HCT116, NCI-H460, BRO, GRANTA-519, HL-60, THP-1, and Raji cells with EC50 of 23 nM, 21 nM, 11 nM, 15 nM, 32 nM, 36 nM, and 37 nM, respectively. BI6727 treatment (100 nM) in NCI-H460 cells induces an accumulation of mitotic cells with monopolar spindles and positive staining for histone H3 phosphoserine 10, confirming that cells are arrested early in the M phase, followed by induction of apoptosis. ^[1] Low nanomolar concentrations of BI6727 display potent inhibitory activity against neuroblastoma (NB) tumor-initiating cells (NB TIC) with EC50 of 21 nM, whereas only micromolar concentrations of BI6727 are cytotoxic for normal pediatric neural stem cells. ^[2] BI6727 induces growth arrest of Daoy and ONS-76 medulloblastoma cells similar to BI 2536. ^[3]