Optimization techniques for novel c-Met kinase inhibitors.

INTRODUCTION: c-Met kinase plays an important part in the regulation of cell growth, invasion and anti-apoptosis. This enzyme is also an important target in cancer treatment. Through structural optimization and structure-activity studies of drugs currently on the market and those still in clinical trials, a great number of novel c-Met kinase inhibitors have been developed. This review focuses on recent developments in research regarding novel c-Met inhibitor synthesis, optimization, and structure-activity relationship (SAR) studies. Area covered: In this review, the authors discuss the representative research of c-Met inhibitors published in recent years. Furthermore, it provides background research of c-Met kinase inhibitors, the introduction of drugs on the market and in clinical research, and the research progress of novel small molecule inhibitors. In particular, this review emphasizes the important role of '5-atoms linker' in the design of some novel c-Met enzyme inhibitors. Expert opinion: Discovering novel c-Met kinase inhibitors via natural product chemistry may become a new research field. Though it is difficult, the key to developing better c-Met kinase inhibitors is structural optimization.