The Aurora kinases (serine/threonine kinases) were discovered in 1995 during 
studies of mutant alleles associated with abnormal spindle pole formation in 
Drosophila melanogaster. They soon became the focus of much attention because of 
their importance in human biology and association with cancer. Aurora kinases 
are essential for cell division and are primarily active during mitosis. 
Following their identification as potential targets for cancer chemotherapy, 
many Aurora kinase inhibitors have been discovered, and are currently under 
development. The binding modes of Aurora kinase inhibitors to Aurora kinases 
share specific hydrogen bonds between the inhibitor core and the back bone of 
the kinase hinge region, while others parts of the molecules may point to 
different parts of the active site via noncovalent interactions. Currently there 
are about 30 Aurora kinase inhibitors in different stages of pre-clinical and 
clinical development. This review summarizes the characteristics and status of 
Aurora kinase inhibitors in preclinical, Phase I, and Phase II clinical studies, 
with particular emphasis on the mechanisms of action and resistance to these 
promising anticancer agents. We also discuss the validity of Aurora kinases as 
oncology targets, on/off-target toxicities, and other important aspects of 
overall clinical performance and future of Aurora kinase inhibitors.