rn486 and Arthritis--Rheumatoid

A series of novel reversible Btk inhibitors has been designed based on the structure of the recently reported preclinical drug RN486. The synthesis and SAR of these compounds are described. Among these derivatives, compound 16b was identified to be a potent and orally available reversible agent with satisfactory Btk enzymatic and cellular inhibition in vitro, as well as favorable PK properties and inhibition of arthritis in vivo.

Topics: Administration, Oral; Agammaglobulinaemia Tyrosine Kinase; Animals; Arthritis, Rheumatoid; Binding Sites; Cell Line; Drug Design; Female; Half-Life; Humans; Isoquinolines; Male; Molecular Docking Simulation; Protein Kinase Inhibitors; Protein Structure, Tertiary; Protein-Tyrosine Kinases; Pyridones; Rats; Rats, Sprague-Dawley; Rats, Wistar; Structure-Activity Relationship

Structure-based drug design was used to guide the optimization of a series of selective BTK inhibitors as potential treatments for Rheumatoid arthritis. Highlights include the introduction of a benzyl alcohol group and a fluorine substitution, each of which resulted in over 10-fold increase in activity. Concurrent optimization of drug-like properties led to compound 1 (RN486) ( J. Pharmacol. Exp. Ther. 2012 , 341 , 90 ), which was selected for advanced preclinical characterization based on its favorable properties.

Topics: Agammaglobulinaemia Tyrosine Kinase; Arthritis, Rheumatoid; Crystallography, X-Ray; Drug Design; Humans; Isoquinolines; Models, Chemical; Models, Molecular; Molecular Structure; Protein Binding; Protein Structure, Secondary; Protein Structure, Tertiary; Protein-Tyrosine Kinases

Bruton's tyrosine kinase (Btk) is required for B lymphocyte and myeloid cell contributions to pathology in murine models of arthritis. Here, we examined the potential contributions of synovial Btk expression and activation to inflammation in rheumatoid arthritis (RA).. Btk was detected by immunohistochemistry and digital image analysis in synovial tissue from biologically naive RA (n=16) and psoriatic arthritis (PsA) (n=12) patients. Cell populations expressing Btk were identified by immunofluorescent double labelling confocal microscopy, quantitative (q-) PCR and immunoblotting. The effects of a Btk-specific inhibitor, RN486, on gene expression in human macrophages and RA synovial tissue explants (n=8) were assessed by qPCR, ELISA and single-plex assays.. Btk was expressed at equivalent levels in RA and PsA synovial tissue, restricted to B lymphocytes, monocytes, macrophages and mast cells. RN486 significantly inhibited macrophage IL-6 production induced by Fc receptor and CD40 ligation. RN486 also reduced mRNA expression of overlapping gene sets induced by IgG, CD40 ligand (CD40L) and RA synovial fluid, and significantly suppressed macrophage production of CD40L-induced IL-8, TNF, MMP-1 and MMP-10, LPS-induced MMP-1, MMP-7 and MMP-10 production, and spontaneous production of IL-6, PDGF, CXCL-9 and MMP-1 by RA synovial explants.. Btk is expressed equivalently in RA and PsA synovial tissue, primarily in macrophages. Btk activity is needed to drive macrophage activation in response to multiple agonists relevant to inflammatory arthritis, and promotes RA synovial tissue cytokine and MMP production. Pharmacological targeting of Btk may be of therapeutic benefit in the treatment of RA and other inflammatory diseases.

Topics: Adult; Agammaglobulinaemia Tyrosine Kinase; Aged; Arthritis, Rheumatoid; B-Lymphocytes; Female; Gene Expression; Humans; Immunohistochemistry; Interleukin-6; Isoquinolines; Macrophages; Male; Mast Cells; Microscopy, Confocal; Middle Aged; Protein-Tyrosine Kinases; Synovial Membrane