April 2014

Hypoxia and STAT3 signalling interactions regulate pro-inflammatory pathways in rheumatoid arthritis

. ARD published online first 13 Feb 2014. Doi: 10.1136/annrheumdis-2013-204105

Hypoxia is a key driving force in joint inflammation, however little is known about the effect it can have on JAK/STAT signalling in rheumatoid arthritis. Due to the development of JAK inhibitors as therapeutics it is important to understand any links there may be. Previous studies have shown that HIF1a, a protein associated with hypoxia, facilitates the binding of STAT3 to haptoglobin promoter in HepG2 human hepatoma cells. HIF1a also requires interaction of Notch signalling pathways with STAT3...

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March 2014

Inhibition of TAK1 and/or JAK can rescue impaired chondrogenic differentiation of human mesenchymal stem cells in osteoarthritis-like conditions

Tissue Engineering Part A doi:10/1089/ten.TEA.2013.0553

As it is nonvascularized and noninnervated, articular cartilage has a limited capacity to repair which presents a major clinical problem. In order to circumvent this inability to repair, stem cells can be placed into the joint or stimulated within the bone marrow. However, as the cartilage requiring repair is often in diseased joints, the factors involved in the disease state are potentially non-beneficial to the chondrogenesis of mesenchymal stem cells. In this study van Beuningen et al. invest...

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February 2014

Efficacy of conventional synthetic disease-modifying antirheumatic drugs, glucocorticoids and tofacitinib: a systematic literature review informing the 2013 update of the EULAR recommendations for the management of rheumatoid arthritis

Ann Rheum Dis doi:10.1136/annrheumdis-2013-204588

Systematic literature reviews were undertaken to assess the efficacy of csDMARDs, glucocorticoids and tofacitinib in the treatment of RA. The first two were updates to reviews conducted for the 2010 recommendations while the tofacitinib SLR was a complete review.Two studies identified by the csDMARD SLR, tREACH and TEAR, compared efficacy between MTX mono- and combination therapy (MTX+SSZ+HQ). Both of these studies found there was no benefit to immediate triple therapy.Further studies analysing ...

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The Pharmacokinetics, Metabolism, and Clearance Mechanisms of Tofacitinib, a Janus Kinase Inhibitor, in Humans

DMD doi:10.1124/dmd.113.054940

The PK of tofacitinib has previously been described in several papers covering a range of diseases. This current study was used to better understand the PK, metabolism and clearance mechanisms of tofacitinib in healthy human subjects. Six subjects took a single 50mg dose of 14C-tofacitinib orally and consequently had urine, faeces and plasma collected. These were assayed for radioactivity and profiled for metabolites. Tofacitinib was found to be rapidly absorbed, with peak plasma concentrations ...

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Effects of tofacitinib on lymphocytes in rheumatoid arthritis: relation to efficacy and infectious adverse events

Rheumatology doi:10.1093/rheumatology/ket466

Due to its function as a JAK1/3 inhibitor, tofacitinib has effects on a wide ranging variety of cells. The authors of this paper have previously reported a suppression in cytokine production by CD4+ T lymphocytes caused by tofacitinib, while others have reported reduced chemokine production from fibroblast-like synoviocytes. The effects of tofacitinib on other cells however remain largely unknown. This study focused on tofacitinib’s effects on CD4+ T lymphocyte proliferation and on subsets of ly...

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January 2014

Selective inhibition of spleen tyrosine kinase (SYK) with a novel orally bioavailable small molecule inhibitor, RO9021, impinges on various innate and adaptive immune responses: implication for SYK inhibitors in autoimmune disease therapy

Arthritis Research and Therapy 2013 15:R146

Spleen tyrosine kinase (SYK) has already been described as a potential therapeutic target for the treatment of autoimmune diseases. Previously the SYK inhibitor fostamatinib was in clinical development for the treatment of rheumatoid arthritis, but has since been suspended. However, investigation into SYK inhibition continues with RO2091, a novel ATP-competitive inhibitor of SYK with reasonable selectivity, potency and oral bioavailability which has been shown to suppress various innate and adap...

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Genome-wide association studies to advance our understanding of critical cell types and pathways in rheumatoid arthritis: recent findings and challenges

Curr. Opin. Rheumatol. 2014; 26:85–92. doi:10.1097/BOR.0000000000000012

A large number of loci implicated in disease susceptibility have been identified through genome-wide association studies (GWAS). In this review article, Diogo et al. discuss recent advances in GWAS in the context of rheumatoid arthritis pathogenesis and clinical applications. Relevant cells types and pathways in RA highlighted by GWAS to date include regulatory T-cells and CD4+ memory T cells as well as the JAK/STAT and NF-kB signalling pathways. The development of drugs targeting these pathways...

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Emerging cell and cytokine targets in rheumatoid arthritis

Nat Rev Rheumatol. 2013. doi:10.1038/nrrheum.2013.168

Despite major progress in the treatment of RA over the past decade, sustained clinical remission remains elusive. The identification of new treatment targets is therefore necessary, with much research currently being undertaken in this area. Novel therapeutic approaches currently being investigated include T cell-directed therapies targeting both T cell activation and regulation; and the targeting of pathogenic B cell functions, including the use of depleting and non-depleting B cell-directed an...

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Preclinical to Clinical Translation of Tofacitinib, a Janus Kinase Inhibitor, in Rheumatoid Arthritis

J Pharmacol Exp Ther. 2013. DOI:10.1124/jpet.113.209304

Preclinical studies can provide insight into mechanisms of efficacy and optimal dosing regimens. In this study, Dowty et al. compare the pharmacokinetic / pharmacodynamic profiles of tofacitinib in a murine arthritis model and in patients with rheumatoid arthritis from tofacitinib clinical trials. The main driver of efficacy in both preclinical murine arthritis models and clinical RA was found to be inhibition of JAK1 heterodimer signalling, where total drug exposure (Cave) was a predictor of pr...

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November 2013

Therapeutic Targeting of the JAK/STAT Pathway

Basic Clin Pharmacol Toxicol. 2013 Oct 24. doi: 10.1111/bcpt.12164

The inhibition of the JAK/STAT pathway has proven to be a powerful therapeutic tool in the treatment of autoimmune diseases. The authors review the role of the JAK/STAT pathway in human disease, including the role of mutations in defective function of this pathway. They discuss the rationale behind JAK inhibition and review the two JAK inhibitors currently approved by the FDA for clinical use; tofacitinib, for the treatment of RA, and ruxolitinib, for the treatment of polycythaemia vera and myel...

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