Design, Synthesis, and Biological Evaluation of Orally Bioavailable CHK1 Inhibitors Active against Acute Myeloid Leukemia.

Checkpoint kinase 1 (CHK1) is a central component in DNA damage response and has emerged as a target for antitumor therapeutics. Herein, we describe the design, synthesis, and biological evaluation of a novel series of potent diaminopyrimidine CHK1 inhibitors. The compounds exhibited moderate to potent CHK1 inhibition and could suppress the proliferation of malignant hematological cell lines. The optimized compound 13 had a CHK1 IC50 value of 7.73±0.74 nM, and MV-4-11 cells were sensitive to it (IC50 =0.035±0.007 µM). Furthermore, compound 13 was metabolically stable in mouse liver microsomes in vitro and displayed moderate oral bioavailability in vivo. Moreover, treatment of MV-4-11 cells with compound 13 for 2 h led to robust inhibition of CHK1 autophosphorylation on serine 296. Based on these biochemical results, we consider compound 13 to be a promising CHK1 inhibitor and potential anticancer therapeutic agent.

Discovery of (R)-5-((5-(1-methyl-1H-pyrazol-4-yl)-4-(methylamino)pyrimidin-2-yl)amino)-3-(piperidin-3-yloxy)picolinonitrile, a novel CHK1 inhibitor for hematologic malignancies.

Through virtual screening, we identified the lead compound MCL1020, which exhibited modest CHK1 inhibitory activity. Then a series of 5-(pyrimidin-2-ylamino)picolinonitrile derivatives as CHK1 inhibitors were discovered by further rational optimization. One promising molecule, (R)-17, whose potency was one of the best, had an IC50 of 0.4 nM with remarkable selectivity (>4300-fold CHK1 vs. CHK2). Compound (R)-17 effectively inhibited the growth of malignant hematopathy cell lines especially Z-138 (IC50: 0.013 µM) and displayed low affinity for hERG (IC50 > 40 µM). Moreover, (R)-17 significantly suppressed the tumor growth in Z-138 cell inoculated xenograft model (20 mg/kg I.V., TGI = 90.29%) as a single agent with body weight unaffected. Taken together, our data demonstrated compound (R)-17 could be a promising drug candidate for the treatment of hematologic malignancies.

Identification of novel inhibitors of Aurora A with a 3-(pyrrolopyridin-2-yl)indazole scaffold.

A novel series of 3-(pyrrolopyridin-2-yl)indazole derivatives were synthesized and biologically evaluated for their anti-proliferative effects on five human cancer cell lines. As a result, all of them exhibited vigorous potency against HL60 cell line with IC50 values ranging from singe digital nanomolar to micromolar level. Besides, a majority of them displayed modest to good antiproliferative activities against the other four cell lines, including KB, SMMC-7721, HCT116, and A549. Particularly, compound 2y, as the most distinguished one in this series, demonstrated IC50 values of 8.3nM and 1.3nM against HL60 and HCT116 cell lines, respectively. Afterwards, for exploring the molecular target, compounds2d, 2g and 2y were further selected to evaluate the inhibitory activities against a panel of kinases. Finally, they were identified to be targeting Aurora A kinase with significant selectivity over other kinases, such as CHK1, CDK2, MEK1, GSK3ß, BRAF, IKKß and PKC.

Design, synthesis and biological evaluation of thienopyridinones as Chk1 inhibitors.

A series of thienopyridinone derivatives was designed and synthesized as inhibitors of checkpoint kinase 1 (Chk1). Most of them exhibited moderate to good Chk1 inhibitory activities. Among them, compounds 8q, 8t, and 8w with excellent Chk1 inhibitory activities (IC50 values of 4.05, 6.23, and 2.33nM, respectively) displayed strong synergistic effects with melphalan, a DNA-damaging agent in the cell-based assay. Further kinase profiling indicated that compound 8t was highly selective against CDK2/cyclinA, Aurora A, and PKC.