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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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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October 2013

The JAK/STAT signalling pathway has been implicated in the pathogenesis of several inflammatory diseases including inflammatory bowel disease (IBD) and rheumatoid arthritis (RA). In this review, Coskun et al. provide an excellent background overview of the JAK/STAT cascade. They also highlight recent study findings investigating the mechanisms of the JAK/STAT pathway and the anti-inflammatory effects of novel JAK inhibitors in development and in clinical trials, particularly in IBD. In one study...

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JAK inhibitors have been identified as having a critical role as therapeutic targets for autoimmune, inflammatory and oncological diseases. GLPG0634 was shown to inhibit JAK1/JAK2 but with a much greater effect on JAK1, a critical pathway in the signal transduction of many inflammatory cytokines. In rodent testing, GLPG0634 showed significant dose-dependent reduction in disease progression in collagen-induced arthritis models, with comparable efficacy to etanercept. An orally bioavailable treatm...

September 2013

SYK plays a significant role in the immune cell signalling of B cells, mast cells, macrophages and neutrophils. Kaur et al. provide a comprehensive review of the molecule, its role in autoimmune disease and clinical data on its inhibition. The paper covers the basic chemistry of SYK including structure, mechanism of action, synthetic derivatives and function, and the relevance of SYK as a therapeutic target for many autoimmune diseases is discussed. The SYK inhibitors currently in clinical trial...

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Chakravaty et al. provide a comprehensive review of the scientific basis for kinase inhibitor use, and summarise experience from clinical trials in tofacitinib and fostamatinib, plus promising clinical data for p38-MAPK inhibitors and P13K? and P13Kd. The authors highlight potential future directions and challenges in kinase inhibitor research, including the emergence of kinases upstream of p38, such as MKK-3 and MKK-6, and the potential of BTK inhibition. One of the challenges of kinase inhibit...

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Inhibition of spleen tyrosine kinase in the treatment of rheumatoid arthritis

Rheumatology 2013;52:1556–1562 doi:10.1093/rheumatology/ket225

Both the innate and adaptive immune responses are targeted by current RA treatments, but these treatments do not achieve consistent sustained disease remission. Protein kinase inhibitors represent a promising new therapeutic target, owing to their influence on downstream signalling and oral bioavailability. Fostamatinib (R788) has shown ACR20 responses of 67–72% in MTX inadequate responder patients at doses of 100mg bd and 150mg bd. However, the results in biologic non-responder patients were no...

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Fostamatinib (R778) is a prodrug designed to deliver the active metabolite R406 which is an inhibitor of SYK and is currently under investigation for treatment of RA. The three clinical trials, conducted in healthy subjects, included two ascending dose studies and a formulation study. The first was a single ascending dose of R406, from 80-600mg, the second was a single and multiple dose study of fostamatinib in aqueous solution with single doses from 80-400mg and multiple doses of 160mg twice da...

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August 2013

Salgado and colleagues conducted a systematic literature review of the safety profiles of protein kinase inhibitors (PKis) used for the treatment of rheumatoid arthritis (RA). Additionally, the study aims included identification of any class and molecule-related target and off-target adverse events. Data from 11,858 patients across 41 publications (phase 2 and 3 studies and two pooled analyses) were analysed. As well as published trials of PKi in RA, studies on healthy individuals and patients w...
This review focuses on targeting spleen tyrosine kinase (SYK) and Bruton’s tyrosine kinase (BTK) inhibitors as potential immunomodulatory agents for the treatment of autoimmune and inflammatory disorders with SYK inhibition showing encouraging efficacy in patients with RA. The paper describes the role of SYK and BTK in several therapy areas including autoimmune diseases, allergic inflammatory disorders and haematological cancers as well as their role in innate immunity and regulators of adaptive...