Three Aurora kinases (AURKA, AURKB and AURKC) are required for cell division and their activities/expression is increased in many human cancers. Accordingly, AURK inhibitors have entered early clinical trials, but their approval has been delayed due to off-target dose-limiting toxicity. Inhibition of AURKB catalytic activity is distinguished in that does not depend on disruption of spindle microtubules, but targeting catalytic activity disables both mitotic and nondividing cells.