SYK is a core signalling protein that drives inflammatory responses and is fundamental to the propagation of signals via numerous immune receptors. While the clinical development of the first SYK inhibitor, fostamatinib, was stopped due to poor results in the phase 3 RA programme, there remain important questions of mechanism which may aid future developments of this target.

In these murine studies, investigators sought to gain an understanding of how the active metabolite of fostamatini...

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January 2014

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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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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Inhibición de la tirosina cinasa esplénica en el tratamiento de la artritis reumatoide

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...

June 2013

This study investigated the capacity of the novel oral spleen tyrosine kinase (Syk) inhibitor R406, and its prodrug R788 (fostamatinib), to suppress the reversed passive Arthrus reaction (RPA) and collagen-induced arthritis (CIA) in rats. R406 (0.1, 1, 5 and 10 mg/kg) and R788 (10 and 30 mg/kg) reduced the cutaneous RPA reaction and inflammatory oedema in a dose-dependent manner, with statistically significant reductions in extravascular leakage and tissue swelling (72% reduction with R406 10 mg...

Un inhibidor oral de la tirosina quinasa esplénica (Syk) para la artritis reumatoide

The New England Journal of Medicine 2010; 363(14):1303-12

This is the first phase 2 study to be published for spleen tyrosine kinase (Syk) inhibitor R788 (fostamatinib). This phase 2 study ingestigated the efficacy and safety of fostamatinib in patients with active RA despite long-term treatment with methotrexate. In this 6-month, double-blind, placebo-controlled trial, patients were randomised to receive two doses of R788 (100 mg twice daily or 150 mg once daily) or placebo once or twice daily. Significantly more patients on R788 achieved ACR 20 respo...