25 years of small molecular weight kinase inhibitors: potentials and limitations.

Deregulation of protein and lipid kinase activities leads to a variety of pathologies, ranging from cancer inflammatory diseases, diabetes, infectious diseases, and cardiovascular disorders. Protein kinases and lipid kinases represent, therefore, an important target for the pharmaceutical industry. In fact, approximately one-third of all protein targets under investigation in the pharmaceutical industry are protein or lipid kinases. To date, 30 kinase inhibitors have been approved, which, with few exceptions, are mainly for oncological indications and directed against only a handful of protein and lipid kinases, leaving 70% of the kinome untapped. Despite these successes in kinase drug discovery, the development of kinase inhibitors with outstanding selectivity, identification and validation of driver kinase(s) in diseases, and the emerging problem of resistance to the inhibition of key target kinases remain major challenges. This minireview provides an insight into protein and lipid kinase drug discovery with respect to achievements, binding modes of inhibitors, and novel avenues for the generation of second-generation kinase inhibitors to treat cancers.