Chemical genomic and proteomic methods for determining kinase inhibitor selectivity

The clinical success of the Bcr-Abl tyrosine kinase inhibitor Gleevec((R)) and the recent clinical approval of a number of small molecule drugs that target protein kinases have intensified the search for novel protein kinase inhibitors. Since most small molecule kinase inhibitors target the highly conserved ATP-binding pocket of this enzyme family, the target selectivity of these molecules is a major concern. Due to the large size of the human kinome, it is a formidable challenge to determine the absolute specificity of a given protein kinase inhibitor, but recent technological developments have made substantial progress in achieving this goal. This review summarizes some of the most recent experimental techniques that have been developed for the determination of protein kinase inhibitor selectivity. Special emphasis is placed on the results of these screens and the general insights that they provide into kinase inhibitor target selectivity.