January 2015

Potential Mechanisms Leading to the Abnormal Lipid Profile in Patients With Rheumatoid Arthritis Versus Healthy Volunteers and Reversal by Tofacitinib

Arthritis Rheumatol. 2015;67(3):616-25.

Active RA is associated with changes in both high- and low-density lipoprotein cholesterol as well as changes in the level and function of several HDL-associated proteins, yet the pathways and mechanisms involved with systemic inflammation altered lipid metabolism have not been determined. In addition, treatments for active RA are known to modify lipid metabolism, such as increasing circulating cholesterol levels. In the clinical development programme, a proportion of tofacitinib-treated patien...

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The pharmacokinetics, pharmacodynamics, and safety of baricitinib, an oral JAK 1/2 inhibitor, in healthy volunteers

Mod J Clin Pharmacol. 2014 Dec;54(12):1354-61. doi: 10.1002/jcph.354.

Current biologic therapies for RA, such as biologic cytokine inhibitors, which selectively target inflammatory molecules with an exquisite degree of specificity, are not clinically effective in all patients with rheumatoid arthritis. As such, there remains an unmet clinical need for more effective and better tolerated therapies. Baricitinib (LY3009104, also previously known as INCB028050) is a potent and selective small molecule inhibitor of JAK1/2, which play an important role in cytokine signa...

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December 2014

Lipid profile changes in patients with chronic inflammatory arthritis treated with biologics and tofacitinib in randomized clinical trials: A systematic review and meta-analysis

Arthritis Rheumatol. 2015;67(1):117–127

Systemic inflammation, reflected by high levels of C-reactive protein and the erythrocyte sedimentation rate, has been identified as an independent risk factor for cardiovascular disease, the most important cause of death in RA and SpA. Studies with TNF antagonists have given contradictory results on cardiovascular risk. As such, this systemic literature search aimed to analyse lipid changes in RA and SpA subjects treated with biologics or tofacitinib in randomized clinical trials.

The s...

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September 2014

The active metabolite of spleen tyrosine kinase inhibitor fostamatinib abrogates the CD4+T cell-priming capacity of dendritic cells

Rheumatology (Oxford). 2015;54(1):169–177

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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August 2014

Changes in serum creatinine in patients with active rheumatoid arthritis treated with tofacitinib: results from clinical trials

Arthritis Res Ther. 2014;16(4):R158

Despite preclinical and healthy volunteer studies of tofacitinib showing no evidence of nephrotoxicity, increases in mean serum creatinine levels have been observed in patients treated with the drug during the RA clinical development programme. This report explores the clinical significance of this change.

Serum creatinine values and renal adverse event data were pooled from patients who received =1 dose of tofacitinib either with background DMARDs or as monotherapy in five Phase 3 studie...

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Analysis of Infections and All-Cause Mortality in Phase II, III and Long-Term Extension Studies of Tofacitinib in Patients with Rheumatoid Arthritis

Arthritis Rheumatol. 2014;66(11):2924–2937

This study pools data from the global tofacitinib RA development programme (phase II, phase III and long-term extension studies) to determine the rate of infections and all-cause mortality with tofacitinib treatment. In total, 4,789 patients within these studies received tofacitinib, at varying doses and with varying duration.

The overall incidence rate of serious infections was 3.09 events/100 patient-years (95% CI 2.73–3.49), which was stable over time, with pneumonia and skin and soft...

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June 2014

Mechanism of Activation of Protein Kinase JAK2 by the Growth Hormone Receptor

Science 344, 2014; doi: 10.1126/science.1249783

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...

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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 ...

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May 2014

JAK2-STAT3 Blockade by AG490 Suppresses Autoimmune Arthritis in Mice via Reciprocal Regulation of Regulatory T cells and Th17 cells

J Immunol 2014; 192:4417-4424

In this study, Park et al sought to investigate the effects of the JAK2 inhibitor, AG490 in RA. Using murine CIA models, both preventative and therapeutic models were investigated. In the preventative model, CIA mice treated with AG490 showed a significantly lower incidence rate of arthritis and arthritic scores when compared to mice injected with vehicle. In the therapeutic model, as in the preventative, AG490 treated mice exhibited less severe arthritis. Through further experiments, it was dem...

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April 2014

Molecular pathways: Molecular basis for sensitivity and resistance to JAK inhibitors

Clin Cancer Research doi:10.1158/1078-0432.CCR-13-0279

Janus kinases (JAKs) mediate the regulation of a variety of cytokine signals with alterations in JAK1, JAK2, JAK3 and Tyk2 signalling contributing to many disease states including autoimmune diseases and haematological malignancies. Recently tofacitinib and ruxolitinib have been approved for treatment for rheumatoid arthritis and myelofibrosis respectively. Several JAK2 inhibitors, such as momelotinib and pacritinib, currently in development for myelofibrosis and the JAK1/2 inhibitor baricitinib...

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