The orally available Btk inhibitor ibrutinib (PCI-32765) protects against osteoclast-mediated bone loss

Bone. 2014 Mar;60:8-15. doi: 10.1016/j.bone.2013.11.025. Epub 2013 Dec 4.

Abstract

Bone-resorbing osteoclasts play an essential role in normal bone homeostasis, as well as in various bone disorders such as osteoporosis and rheumatoid arthritis. Previously we showed that the Tec family of tyrosine kinases is essential for the differentiation of osteoclasts and the inhibition of Btk is a promising strategy for the prevention of the bone loss in osteoclast-associated bone disorders. Here we demonstrate that an orally available Btk inhibitor, ibrutinib (PCI-32765), suppresses osteoclastic bone resorption by inhibiting both osteoclast differentiation and function. Ibrutinib downregulated the expression of NFATc1, the key transcription factor for osteoclastogenesis, and disrupted the formation of the actin ring in mature osteoclasts. In addition, genome-wide screening revealed that Btk regulates the expression of the genes involved in osteoclast differentiation and function in both an NFATc1-dependent and -independent manner. Finally, we showed that ibrutinib administration ameliorated the bone loss that developed in a RANKL-induced osteoporosis mouse model. Thus, this study suggests ibrutinib to be a promising therapeutic agent for osteoclast-associated bone diseases.

Keywords: Btk; Ibrutinib; Inflammatory bone destruction; Osteoclast; Osteoporosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Agammaglobulinaemia Tyrosine Kinase
  • Animals
  • Bone Resorption / complications
  • Bone Resorption / drug therapy*
  • Bone Resorption / genetics
  • Bone Resorption / prevention & control*
  • Cell Differentiation / drug effects
  • Disease Models, Animal
  • Female
  • Gene Expression Regulation / drug effects
  • Mice
  • Mice, Inbred C57BL
  • Osteoblasts / drug effects
  • Osteoblasts / metabolism
  • Osteoblasts / pathology
  • Osteoclasts / drug effects
  • Osteoclasts / metabolism
  • Osteoclasts / pathology
  • Osteoporosis / complications
  • Osteoporosis / drug therapy
  • Osteoporosis / pathology
  • Osteoporosis / prevention & control
  • Protein Kinase Inhibitors / administration & dosage*
  • Protein Kinase Inhibitors / pharmacology
  • Protein Kinase Inhibitors / therapeutic use*
  • Protein-Tyrosine Kinases / antagonists & inhibitors*
  • Protein-Tyrosine Kinases / metabolism
  • Pyrazoles / administration & dosage*
  • Pyrazoles / pharmacology
  • Pyrazoles / therapeutic use*
  • Pyrimidines / administration & dosage*
  • Pyrimidines / pharmacology
  • Pyrimidines / therapeutic use*
  • RANK Ligand

Substances

  • Protein Kinase Inhibitors
  • Pyrazoles
  • Pyrimidines
  • RANK Ligand
  • ibrutinib
  • Protein-Tyrosine Kinases
  • Agammaglobulinaemia Tyrosine Kinase