Design, synthesis, and biological evaluations of novel 3-amino-4-ethynyl indazole derivatives as Bcr-Abl kinase inhibitors with potent cellular antileukemic activity

Eur J Med Chem. 2020 Dec 1:207:112710. doi: 10.1016/j.ejmech.2020.112710. Epub 2020 Aug 19.

Abstract

Breakpoint cluster region-Abelson (Bcr-Abl) kinase is a key driver in the pathophysiology of chronic myelogenous leukemia (CML). Broadening the chemical diversity of Bcr-Abl kinase inhibitors with novel chemical entities possessing favorable target potency and cellular efficacy is a current medical demand for CML treatment. In this respect, a new series of ethynyl bearing 3-aminoindazole based Bcr-Abl inhibitors has been designed, synthesized, and biologically evaluated. The target compounds were designed based on introducing the key structural features of ponatinib, alkyne spacer and diarylamide, into the previously reported indazole II to improve its Bcr-Abl inhibitory activity and overcome its poor cellular potency. All target compounds elicited potent activity against Bcr-AblWT with sub-micromolar IC50 values ranging 4.6-667 nM. In addition, certain derivatives exhibited promising potency over the clinically imatinib-resistant Bcr-AblT315I. Among the target molecules, compounds 9c, 9h and 10c stood as the most potent derivatives with IC50 values of 15.4 nM, 4.6 nM, and 25.8 nM, respectively, against Bcr-AblWT. Interestingly, 9h showed 2 folds and 3.6 times superior potency to the lead indazole II and 10c, respectively, against Bcr-AblT315I. Molecular docking of 9h pointed out its possibility to be a type II kinase inhibitor. Furthermore, all compounds, except 9b, showed highly potent antiproliferative activity against the Bcr-Abl positive leukemia K562 cell (MTT assay) surpassing the modest activity of lead indazole II. Moreover, the most potent members 9h and 10c exerted potent antileukemic activity against NCI leukemia panel, particularly K562 cell (SRB assay) with GI50 less than 10 nM, being superior to the FDA approved drug imatinib. Further biochemical hERG and cellular toxicity, phosphorylation assay, and NanoBRET target engagement of 9h underscored its merits as a promising candidate for CML therapy.

Keywords: 3-Aminoindazole; Antileukemic activity; Bcr-Abl(T315I); Bcr-Abl(WT); Diarylamide; Ethynyl linker; Imatinib resistance; NanoBRET target engagement.

MeSH terms

  • Amination
  • Antineoplastic Agents / chemical synthesis
  • Antineoplastic Agents / chemistry*
  • Antineoplastic Agents / pharmacology*
  • Cell Proliferation / drug effects
  • Drug Design
  • Fusion Proteins, bcr-abl / antagonists & inhibitors*
  • Fusion Proteins, bcr-abl / metabolism
  • Humans
  • Indazoles / chemical synthesis
  • Indazoles / chemistry*
  • Indazoles / pharmacology*
  • K562 Cells
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive / drug therapy*
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive / metabolism
  • Molecular Docking Simulation
  • Protein Kinase Inhibitors / chemical synthesis
  • Protein Kinase Inhibitors / chemistry
  • Protein Kinase Inhibitors / pharmacology

Substances

  • Antineoplastic Agents
  • Indazoles
  • Protein Kinase Inhibitors
  • Fusion Proteins, bcr-abl