Psoriatic arthritis (PsA) is a chronic inflammatory arthritis associated with psoriasis (Ps) and characterised by synovitis and progressive destruction of articular cartilage and bone. Recently developed agents for PsA target IL12p40, IL-6 and IL-17, several of which signal through the JAK family of receptor-associated tyrosine kinases. Tofacitinib is a drug of the JAK inhibitor class and is currently approved for the treatment of RA in 27 countries. This study evaluated the effect of tofacitini...

July 2015

The humanised anti-interleukin 6 receptor monoclonal antibody tocilizumab (TCZ) has been available in clinical practice for several years. The purpose of this study was to evaluate the long-term safety of for the treatment of RA in a real-world clinical setting as a long-term extension of a single-arm, observational post marketing surveillance study. Data on selected adverse events (AEs) - fatal events, serious infection, malignancy, GI perforation, and serious cardiac dysfunction - were collect...

May 2015

Mean increases from baseline in patient serum creatinine (SCr) levels have been observed in the clinical development programme for the JAK inhibitor tofacitinib. These increases predominantly occurred within the first three months, and reversed with tofacitinib withdrawal.

This phase 1, randomised, placebo-controlled, parallel-group, 2-period study assessed changes in measured glomerular filtration rate (mGFR) with tofacitinib, relative to placebo, in 148 patients with active RA. Result...

Tofacitinib, an oral Janus kinase inhibitor: analysis of malignancies across the rheumatoid arthritis clinical development programme

Ann Rheum Dis. 2015 Apr 22. pii: annrheumdis-2014-205847. doi: 10.1136/annrheumdis-2014-205847. [Epub ahead of print]

The developments of certain malignancies associated with chronic inflammatory diseases such as RA is known to occur to a greater extent than that of the general population. It is also know that certain RA treatments can affect malignancy rates. As such, newer immunomodulatory agents, such as the JAK inhibitor tofacitinib, are closely monitored for safety events of special interest, including malignancies.

This paper analyses pooled malignancy data from the tofacitinib RA clinical develop...

April 2015

Super-enhancers delineate disease-associated regulatory nodes in T cells

Nature. 2015 Feb 16. doi: 10.1038/nature14154. [Epub ahead of print]

Transcription machinery (proteins responsible for activating or ‘switching off’ genes) is not distributed in the genome in a symmetrical (or even) manner. Some parts of the genome, so called super-enhancers (SEs), accumulate an exceptionally high level of proteins relevant to the regulation of transcription (i.e. the machinery is concentrated in particular parts of the genome). In this paper, the investigators asked about the locale of these regions in the genome of T cells. Then they addressed...

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December 2014

Recent innovations in the treatment of RA have focused on the use of small molecules to inhibit intracellular kinases such as the JAK family. Baricitinib (LY3009104, formerly INCB028050) is an orally administered, potent, selective and reversible inhibitor of JAK1 and JAK2, which has shown anti-inflammatory effects, as well as preservation of cartilage and bone, in preclinical rodent studies.

This phase IIb study was designed to investigate multiple doses and dosing regimens of baricitin...

The JAK inhibitor tofacitinib suppresses synovial JAK1-STAT signalling in rheumatoid arthritis

Ann Rheum Dis. 2014 Nov 14. pii: annrheumdis-2014-206028. doi: 10.1136/annrheumdis-2014-206028. [Epub ahead of print]

Targeting intracellular pathways such as JAK/STAT represents a novel approach to the treatment of RA. Tofacitinib is an oral JAK inhibitor, proven to be effective in the treatment of RA, yet the pathways affected by tofacitinib and the effects on gene expression in situ are unknown. In this study, Boyle et al. tested the hypothesis that tofacitinib targets cytokine signalling critical to the pathogenesis of rheumatoid synovitis by investigating tofacitinib effects on synovial pathobiology.

June 2014

Class I cytokine receptors are key regulators of many processes within the body. The receptors use the JAK-STAT signalling pathway, the deregulation of which causes it to become an important pathway in oncogenesis. Despite this, the processes responsible for JAK2 activation by class I receptors remains elusive. Previous studies using growth hormone and its receptor have led to a model of receptor activation where hormone induced receptor dimerization resulted in close proximity of the receptor i...
The JAK family of kinases (JAK1, JAK2, JAK3 and TYK2) are receptor-associated tyrosine kinases that act downstream of many cytokines and interferons. Recent studies have provided structural information about the kinase and pseudokinase domains of JAKs however the molecular mechanism by which JAK activity is regulated by the pseudokinase domain is poorly understood. This study builds on a recent finding that the N terminus of the JAK1 pseudokinase group may act as a switch for kinase activation b...

Structural basis for the recognition of interferon-α receptor by tyrosine kinase 2

Nat Struct Mol Biol. 2014 May;21(5):443-8. doi: 10.1038/nsmb.2807. Epub 2014 Apr 6

Janus kinases, JAKs, are essential in the mediation of cytokine and interferon signalling whilst also being crucial to body processes such as immune function, hematopoeises, metabolism and cellular growth. However, it is not known is how the four members of the JAK family interact with and are activated by over 30 cytokine receptors with near perfect affinity and specificity. Currently, there are no crystal structures available for any JAK bound to a cytokine receptor. This study sought address ...