Potent, non-covalent reversible BTK inhibitors with 8-amino-imidazo[1,5-a]pyrazine core featuring 3-position bicyclic ring substitutes

Bioorg Med Chem Lett. 2020 Sep 1;30(17):127390. doi: 10.1016/j.bmcl.2020.127390. Epub 2020 Jul 11.


Bruton's tyrosine kinase (BTK) is a Tec family kinase with a well-defined role in the B cell receptor (BCR) pathway. It has become an attractive kinase target for selective B cell inhibition, and for the treatment of B cell related diseases. Many BTK inhibitors have been discovered for the treatment of cancer and rheumatoid arthritis, including a series of BTK inhibitors based on 8-amino-imidazo[1,5-a]pyrazine we recently reported. The X-ray crystal structures of BTK with inhibitors were also published, which provided great help for the SAR design. Here we report our SAR work introducing ring constraints for the 3-position piperidine amides on the BTK inhibitors based on 8-amino-imidazo[1,5-a]pyrazine. This modification improved the potency in BTK inhibitions, as well as the PK profile and the off-target selectivity. The dose-dependent efficacy of two BTK inhibitors was observed in the rat collagen induced arthritis (CIA) model.

Keywords: Bruton’s Tyrosine Kinase; Kinase selectivity; Rat CIA model; Structure based drug design; X-ray crystal structure.

MeSH terms

  • Agammaglobulinaemia Tyrosine Kinase / antagonists & inhibitors*
  • Agammaglobulinaemia Tyrosine Kinase / metabolism
  • Animals
  • Arthritis, Experimental / drug therapy
  • Binding Sites
  • Bridged Bicyclo Compounds / chemistry
  • Crystallography, X-Ray
  • Disease Models, Animal
  • Dogs
  • Dose-Response Relationship, Drug
  • Half-Life
  • Humans
  • Imidazoles / chemistry*
  • Imidazoles / metabolism
  • Imidazoles / therapeutic use
  • Molecular Dynamics Simulation
  • Protein Kinase Inhibitors / chemistry*
  • Protein Kinase Inhibitors / metabolism
  • Protein Kinase Inhibitors / therapeutic use
  • Pyrazines / chemistry*
  • Pyrazines / metabolism
  • Pyrazines / therapeutic use
  • Rats
  • Rats, Wistar
  • Structure-Activity Relationship
  • src-Family Kinases / antagonists & inhibitors
  • src-Family Kinases / metabolism


  • Bridged Bicyclo Compounds
  • Imidazoles
  • Protein Kinase Inhibitors
  • Pyrazines
  • imidazo(1,5-a)pyrazine
  • Agammaglobulinaemia Tyrosine Kinase
  • src-Family Kinases