Exploration of chemical space based on 4-anilinoquinazoline

Chemical space is defined as all possible small organic molecules, including those present in biological systems, which is so vast that so far only a tiny fraction of it has been explored. Indeed, a thorough examination of all "chemical space" is practically impossible. The success of three EGFR inhibitors (Gefitnib, Erlotinib, Lapatinib) suggests that 4-anilinoquinazoline scaffold is still worth developing in the future. To date hundreds of this sort of derivatives have been synthesized and show potent anticancer activities. Most of the compounds have been proved to be EGFR/HER2 kinase inhibitors, binding at the hinge region of the ATP site and some lead compounds have been optimized against a number of different kinases, including VEGFR-2, Src, Aurora A/B, Tpl, Clk and PDE10A. Now there is now a rich pipeline of novel anticancer agents based on 4-anilinoquinazoline in early phase clinical trials. This review will highlight the exploration of chemical space of 4-anilinoquinazoline in the past ten years and we hope that increasing knowledge of the SAR and cellular processes underlying the antitumor-activity of anilinoquinazoline derivatives will be beneficial to the rational design of new generation of small molecule anticancer drugs.