The purpose of this Phase I, first time in human (FTIH) study in subjects with refractory cancers is to determine the maximally tolerated dose (MTD) (or recommended dose based on available safety, pharmacokinetic (PK) and response data), dose-limiting toxicities (DLTs), PK, pharmacodynamics (PD), and preliminary clinical activity of GSK923295, an inhibitor of CENP-E.