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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The 2010 EULAR recommendations represented a significant step forward in the management of rheumatoid arthritis, and they have been widely adopted across the world. However, in the rapidly evolving world of rheumatology, it was recognised that a substantial amount of new evidence has accumulated, both on agents approved at that time as well as data on new compounds that have become available over the last 3–4 years. This motivated EULAR to form an international task force to update their recomme...

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October 2013

The role of p38-MAPK inhibitors in treating RA is the subject of some debate. Li et al. therefore performed the first meta-analysis of the current data to evaluate the efficacy and safety of these compounds. The authors identified 3 papers, covering 4 RCTs, for analysis and the results showed that p38-MAPK inhibition achieves a better level of ACR20 improvement vs. placebo, but showed no meaningful difference in ACR50, DAS28 or CRP levels past week 12. Due to the inadequate number and quality of...

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Many patients with active RA have an inadequate response to biologic and nonbiologic DMARDs. Kremer et al carried out a one year, randomized trial studying the efficacy of tofacitinib in conjunction with background nonbiologic DMARDs (primarily methotrexate) in these patients. The results showed that using tofacitinib in combination with nonbiologic DMARDs rapidly improved physical function and reduced signs and symptoms of RA versus placebo, measured by ACR20 rates, DAS28 and HAQ-DI. The data f...

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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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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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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 phase2 trial assessed the efficacy of GLPG0259, a first-in-class ATP-competitive inhibitor of MAPKAPK5. The trail involved 31 patients with active RA and an inadequate response MTX. Patients received either 50 mg/day GLPG0259 with MTX or a placebo with MTX (patients randomised 2:1) for 12 weeks with the primary efficacy variable being ACR 20 response at week 12. Analysis showed that 5 patients (26.3%) in the GLPG0259 group and 3 patients (27.3%) in the placebo group achieved ACR 20 at 12 we...

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The JAK inhibitor tofacitinib for active rheumatoid arthritis: results from phase III trials

International Journal of Clinical Rheumatology June 2013; 8(3):311–13

The tofacitinib ORAL research program involves six phase 3 trials (Standard, Solo, Step, Scan, Sync and Start) to assess the safety and efficacy of tofacitinib 5 and 10 mg twice daily as monotherapy, or with either background MTX or traditional DMARD therapy. This report by Salgado et al. provides an overall analysis of the each of the study designs and the clinical results to date. The results show that tofacitinib effectively controlled the signs and symptoms of RA across a range of patient po...

June 2013

An Oral Spleen Tyrosine Kinase (Syk) Inhibitor for Rheumatoid Arthritis

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...