Design,Synthesis And Biological Evaluation Of Thienopyridinone And 2-amino Pyrimidine Derivatives As Chk1 Inhibitors

Malignant neoplasm has become the number one killer in China.In recent years,a large number of molecular targeted anti-cancer agents have advanced into clinical applications,whereas single targeted anti-cancer agents are not sufficient for cancer treatment due to tumor complexity and hereditary multiplicity.Although traditional DNA damaging agents could extend the lifetime of cancer patients,poor selectivity and severe side effects limited their further utilizations in the clinical trials.Therefore,the strategy of developing cell cycle associated agents in combination with DNA damaging agents has emerged as one of the hot spots in the anti-cancer field.Enlightened by the structural features of cell cycle checkpoint kinase 1(Chkl)inhibitors published in the literatures as well as their binding modes,28 thienopyridinones were designed and synthesized based on the bioisosterism strategy.Besides,the preliminary structure-activity relationship(SAR)was disclosed.In vitro Chkl inhibitory activities indicated that most of the compounds demonstrated modest to good potency,among which,the IC50 values of ten compounds were less than 10 nM.Meanwhile,several compounds displayed excellent selectivity profiles against some other kinases.Three representative compounds 1-65,1-68 and 1-71 showed significant synergistic effect with Melphalan against RPMI-8226 tumor cell line with little single agent efficacy.As a continuation of our study toward structural modifications of thienopyridinone derivatives as Chkl inhibitors,four 3-indole-pyridinone derivatives were designed and synthesized according to scaffold morphing strategy based on a combinational analysis of CHIR-124 and the indole-quinolinone based derivative 2-1.Unfortunately,all the four compounds displayed no Chkl inhibitory activity,while compound 2-22 showed modest Aurora A inhibition with IC50 value of 1.23 μM when screening against other targets,including IKKβ,CDK2/cyclinA,Aurora A and PKC.In order to discover novel scaffolds of Chkl inhibitors,we screened the Chembridge database and our in-house compound library based on the established structure-based virtual screening model,in combination with biological evaluation and led to the identification of MCL1020 with modest potency.According to its structural features,series of 62 N-substituted pyridine/pyrimidine-2-amino pyrimidine derivatives were designed and synthesized via utilizing scaffold morphing strategy as well as some other rational drug design approaches.Most of the target compounds exhibited modest to good Chkl inhibitory activities.Among them,the IC50 values of 25 compounds were less than 10 nM.Four representative compounds displayed significant synergistic effect against SW620 tumor cell line in combination with Gemcitabine.Western blotting results indicated that Chkl phosphorylation on S296 induced by Gemcitabine could be suppressed by compound 3-94 at both concentrations of 0.1 and 0.5 μM.In vitro evaluation against five different hematological tumor cell lines revealed that N-substituted pyridine-2-amino pyrimidine derivatives displayed excellent antiproliferative activities against human acute leukemia MV-4-11 cell line.To explore their druggability,four representative compounds were tested,which showed good mouse liver microsome stability and MDCK transportation.Based on the above in vitro kinase and cellular results,compound 3-209 was selected and evaluated in MV-4-11 xenograft models in nude mice,which indicated significant tumor growth inhibition.In the pharmacokinetic assay,compound 3-94 with modest oral bioavailability(F = 37%)indicated more favorable PK properties relative to 3-209,which laid a solid foundation for further in vivo pharmacodynamic studies and mechanism of action.