Design, Synthesis And Antitumor Evalution Of Novel Nek2 Kinase Inhibitors

NIMA-related kinase 2 (Nek2) is a serine/threonine kinase that serves as a key regulator of mitotic processes, such as centrosome duplication and spindle assembly through phosphorylation of substrate proteins. Deregulation of mitotic processes can lead to genomic instability and aneuploidy, which is a characteristic of all tumors and is a hallmark of cancer. Nek2 expression in cancer cells is directly related to enhanced genomic instability, cell proliferation, and drug resistance. Therefore, Nek2 represents a novel biomarker to predict cancer prognosis and drug resistance and can also serve as a well-documented and an important therapeutic target to treat human cancers.However, the design of a Nek2 inhibitor with adequate drug-like properties has been challenging. There are very few Nek2 inhibitors described in the literature and they only have kinase and cell activity, and the cell activity are relatively low. No inhibitor has showed in vivo antitumor activity. To further investigate the role of Nek2 biology and to progress Nek2 as an oncology target, we hope to be able to develop novel and potent Nek2 inhibitors with adequate in vitro and in vivo antitumor activity.Therefore, we first reviewed the found, structures, subtypes, biological functions of Nek2 kinase and the relationship with tumor in the introduction of this paper. Then through the system research and analysis of structure-activity relationship (SAR) of the reported small molecule inhibitors, we found the challenges, commonness and regularities of the design of Nek2 inhibitors, which provided us guidance and help when we subsequent independently designed Nek2 inhibitors.We designed and sythesized a series of novel Nek2 inhibitorers based on imidazo[1,2-a]pyridine-core through using bioisostere, fragment based on drug design, structure based design and hybrid molecule strtegies, combining with computer-aided drug design and other means. A nonlinear SAR was identified displaying that substitution at the 7-position of imidazo[1,2-a]pyridine and benzyl group substituents are critical for Nek2 potency and cancer cell activity. Furthermore, an unsubstituted primary amide is important to maintain Nek2 activity. The extensive imidazo[1,2-a]pyridine SAR studies provided a comprehensive guide to aid in the improvement of Nek2 activity for future medicinal chemistry campaigns.In addition, to the potent Nek2 inhibitors, we further investigated their influence on cell cycle and apopotosis, pharmacokinetic (PK) and in vivo activity. MBM-17 (IC50= 3.0 nM) and MBM-55 (IC50=1.0 nM) are the most potent Nek2 inhibitors up to now. Furthermore, MBM-17 and MBM-55 were shown to promote sustained delay in the G2/M cell-cycle phase and, in a dose dependent manner, induce apoptosis. MBM-17 and MBM-55 displayed good selectivity and pharmacokinetic properties. MBM-17S and MBM-55S displayed significant in vivo antitumor activity with no obvious signs of toxicity.Given that very few inhibitors with Nek2 celluar activity have been identified, this research is a major milestone for Nek2 small molecule inhibitors. MBM-17 and MBM-55 displaye the potential for substantial therapeutic application in cancer treatment. In the future, MBM-17 and MBM-55 will serve as excellent lead compounds in the search for a Nek2 preclinical candidate.