Tetrahydroindazoles as Interleukin-2 Inducible T-Cell Kinase Inhibitors. Part II. Second-Generation Analogues with Enhanced Potency, Selectivity, and Pharmacodynamic Modulation in Vivo

J Med Chem. 2015 May 14;58(9):3806-16. doi: 10.1021/jm501998m. Epub 2015 Apr 16.


The medicinal chemistry community has directed considerable efforts toward the discovery of selective inhibitors of interleukin-2 inducible T-cell kinase (ITK), given its role in T-cell signaling downstream of the T-cell receptor (TCR) and the implications of this target for inflammatory disorders such as asthma. We have previously disclosed a structure- and property-guided lead optimization effort which resulted in the discovery of a new series of tetrahydroindazole-containing selective ITK inhibitors. Herein we disclose further optimization of this series that resulted in further potency improvements, reduced off-target receptor binding liabilities, and reduced cytotoxicity. Specifically, we have identified a correlation between the basicity of solubilizing elements in the ITK inhibitors and off-target antiproliferative effects, which was exploited to reduce cytotoxicity while maintaining kinase selectivity. Optimized analogues were shown to reduce IL-2 and IL-13 production in vivo following oral or intraperitoneal dosing in mice.

MeSH terms

  • Animals
  • Cell Proliferation / drug effects
  • Crystallography, X-Ray
  • Cytotoxins / chemistry
  • Cytotoxins / pharmacology
  • Cytotoxins / toxicity
  • Female
  • Humans
  • Indazoles / chemistry*
  • Indazoles / pharmacology
  • Indazoles / toxicity
  • Interleukin-13 / biosynthesis
  • Interleukin-2 / biosynthesis
  • Jurkat Cells
  • Mice, Inbred C57BL
  • Models, Molecular
  • Molecular Structure
  • Phosphorylation
  • Protein-Tyrosine Kinases / antagonists & inhibitors*
  • Receptors, Antigen, T-Cell / metabolism
  • Stereoisomerism
  • Structure-Activity Relationship
  • Sulfones / chemistry
  • Sulfones / pharmacology
  • Sulfones / toxicity
  • Sulfoxides / chemistry
  • Sulfoxides / pharmacology
  • Sulfoxides / toxicity


  • Cytotoxins
  • Indazoles
  • Interleukin-13
  • Interleukin-2
  • Receptors, Antigen, T-Cell
  • Sulfones
  • Sulfoxides
  • Protein-Tyrosine Kinases
  • emt protein-tyrosine kinase