TRAFIC: statistical design and analysis plan for a pragmatic early phase 1/2 Bayesian adaptive dose escalation trial in rheumatoid arthritis.

BACKGROUND: Adaptive model-based dose-finding designs have demonstrated advantages over traditional rule-based designs but have increased statistical complexity but uptake has been slow especially outside of cancer trials. TRAFIC is a multi-centre, early phase trial in rheumatoid arthritis incorporating a model-based design. METHODS: A Bayesian adaptive dose-finding phase I trial rolling into a single-arm, single-stage phase II trial. Model parameters for phase I were chosen via Monte Carlo simulation evaluating objective performance measures under clinically relevant scenarios and incorporated stopping rules for early termination. Potential designs were further calibrated utilising dose transition pathways. DISCUSSION: TRAFIC is an MRC-funded trial of a re-purposed treatment demonstrating that it is possible to design, fund and implement a model-based phase I trial in a non-cancer population within conventional research funding tracks and regulatory constraints. The phase I design allows borrowing of information from previous trials, all accumulated data to be utilised in decision-making, verification of operating characteristics through simulation, improved understanding for management and oversight teams through dose transition pathways. The rolling phase II design brings efficiencies in trial conduct including site and monitoring activities and cost. TRAFIC is the first funded model-based dose-finding trial in inflammatory disease demonstrating that small phase I/II trials can have an underlying statistical basis for decision-making and interpretation. TRIAL REGISTRATION: Trials Registration: ISRCTN, ISRCTN36667085 . Registered on September 26, 2014.

Brain pseudotumour secondary to Behçet's disease.

Neuro-Behçet's disease (NBD) is a serious manifestation of Behçet's disease (BD) and can affect either the central or peripheral nervous systems, or both. It occurs in 10-50% of patients with BD. We report on a patient with an unusual intraparenchymal lesion, initially thought to be a brain tumour. Histological examination revealed vasculitis consistent with BD. Clinicians should include NBD as a differential diagnosis when considering an isolated inflammatory intracranial lesion.

Tolerogenic dendritic cells generated with dexamethasone and vitamin D3 regulate rheumatoid arthritis CD4+ T cells partly via transforming growth factor-ß1.

Tolerogenic dendritic cells (tolDC) are a new immunotherapeutic tool for the treatment of rheumatoid arthritis (RA) and other autoimmune disorders. We have established a method to generate stable tolDC by pharmacological modulation of human monocyte-derived DC. These tolDC exert potent pro-tolerogenic actions on CD4+ T cells. Lack of interleukin (IL)-12p70 production is a key immunoregulatory attribute of tolDC but does not explain their action fully. Here we show that tolDC express transforming growth factor (TGF)-ß1 at both mRNA and protein levels, and that expression of this immunoregulatory cytokine is significantly higher in tolDC than in mature monocyte-derived DC. By inhibiting TGF-ß1 signalling we demonstrate that tolDC regulate CD4+ T cell responses in a manner that is at least partly dependent upon this cytokine. Crucially, we also show that while there is no significant difference in expression of TGF-ßRII on CD4+ T cells from RA patients and healthy controls, RA patient CD4+ T cells are measurably less responsive to TGF-ß1 than healthy control CD4+ T cells [reduced TGF-ß-induced mothers against decapentaplegic homologue (Smad)2/3 phosphorylation, forkhead box protein 3 (FoxP3) expression and suppression of (IFN)-γ secretion]. However, CD4+ T cells from RA patients can, nonetheless, be regulated efficiently by tolDC in a TGF-ß1-dependent manner. This work is important for the design and development of future studies investigating the potential use of tolDC as a novel immunotherapy for the treatment of RA.

Biosimilars in immune-mediated inflammatory diseases: initial lessons from the first approved biosimilar anti-tumour necrosis factor monoclonal antibody.

The introduction of targeted biological therapies has revolutionised the management of immune-mediated inflammatory diseases (IMIDs) such as rheumatoid arthritis, ankylosing spondylitis, psoriasis and inflammatory bowel disease. Following treatment with these therapies, many patients experience significant improvements in different aspects of their disease, including symptoms, work productivity and other outcomes relevant for individuals and society. However, due to the complexity of biological drug development and manufacturing processes, the costs of these therapies are relatively high. Indeed, the financial burden on healthcare systems due to biological therapies is considerable and lack of patient access to effective treatment remains a concern in many parts of the world. As many reference biological therapies have now reached or are near to patent expiry, a number of 'biosimilar' drugs have been developed for use in various clinical settings, and some of these drugs are already in use in several countries. While the potential pharmacoeconomic benefits of cost-effective biosimilars seem clear, several issues have been raised regarding, for example, the definition of biosimilarity and the validity of indication extrapolation, as well as the 'switchability' and relative immunogenicity of biosimilars and their reference drugs. In this review, these issues will be discussed with reference to CT-P13, a biosimilar of the anti-tumour necrosis factor monoclonal antibody infliximab, which is approved in Europe and elsewhere for the treatment of various IMIDs. Other important issues, including those related to data collection during nonclinical and clinical development of biosimilars, are also discussed.

Synovial CD4+ T-cell-derived GM-CSF supports the differentiation of an inflammatory dendritic cell population in rheumatoid arthritis.

OBJECTIVE: A population of synovial inflammatory dendritic cells (infDCs) has recently been identified in rheumatoid arthritis (RA) and is thought to be monocyte-derived. Here, we investigated the role and source of granulocyte macrophage-colony-stimulating factor (GM-CSF) in the differentiation of synovial infDC in RA. METHODS: Production of GM-CSF by peripheral blood (PB) and synovial fluid (SF) CD4+ T cells was assessed by ELISA and flow cytometry. In vitro CD4+ T-cell polarisation experiments were performed with T-cell activating CD2/CD3/CD28-coated beads in the absence or presence of pro-Th1 or pro-Th17 cytokines. CD1c+ DC and CD16+ macrophage subsets were flow-sorted and analysed morphologically and functionally (T-cell stimulatory/polarising capacity). RESULTS: RA-SF CD4+ T cells produced abundant GM-CSF upon stimulation and significantly more than RA-SF mononuclear cells depleted of CD4+ T cells. GM-CSF-producing T cells were significantly increased in RA-SF compared with non-RA inflammatory arthritis SF, active RA PB and healthy donor PB. GM-CSF-producing CD4+ T cells were expanded by Th1-promoting but not Th17-promoting conditions. Following coculture with RA-SF CD4+ T cells, but not healthy donor PB CD4+ T cells, a subpopulation of monocytes differentiated into CD1c+ infDC; a process dependent on GM-CSF. These infDC displayed potent alloproliferative capacity and enhanced GM-CSF, interleukin-17 and interferon-γ production by CD4+ T cells. InfDC with an identical phenotype to in vitro generated cells were significantly enriched in RA-SF compared with non-RA-SF/tissue/PB. CONCLUSIONS: We demonstrate a therapeutically tractable feedback loop of GM-CSF secreted by RA synovial CD4+ T cells promoting the differentiation of infDC with potent capacity to induce GM-CSF-producing CD4+ T cells.

Association of a complement receptor 1 gene variant with baseline erythrocyte sedimentation rate levels in patients starting anti-TNF therapy in a UK rheumatoid arthritis cohort: results from the Biologics in Rheumatoid Arthritis Genetics and Genomics Study Syndicate cohort.

Eligibility for anti-tumour necrosis factor (TNF) therapy in most European countries is restricted to severe, active rheumatoid arthritis (RA). The DAS28 score is a marker of disease severity and incorporates one of two inflammatory markers, erythrocyte sedimentation rate (ESR) or C-reactive protein. We aimed to determine the relation between genetic variants known to affect ESR and levels of ESR in patients with active RA. DNA samples were genotyped for four single-nucleotide polymorphisms (SNPs) rs7527798 (CR1L), rs6691117 (CR1), rs10903129 (TMEM57) and rs1043879 (C1orf63). The association between SNPs and baseline ESR, baseline DAS28-ESR, and change in DAS28-ESR was evaluated. Baseline ESR was significantly associated with CR1 rs6691117 genotype (P=0.01). No correlation was identified between baseline DAS28-ESR or change in DAS28-ESR. In conclusion, genetic variation in the gene encoding CR1 may alter ESR levels but not DAS28-ESR, indicating no adjustment for CR1 genotype is required in the assessment of patients with severe active RA.

Tolerogenic dendritic cell therapy for rheumatoid arthritis: where are we now?

Dendritic cells with tolerogenic function (tolDC) have become a promising immunotherapeutic tool for reinstating immune tolerance in rheumatoid arthritis (RA) and other autoimmune diseases. The concept underpinning tolDC therapy is that it specifically targets the pathogenic autoimmune response while leaving protective immunity intact. Findings from human in-vitro and mouse in-vivo studies have been translated into the development of clinical grade tolDC for the treatment of autoimmune disorders. Recently, two tolDC trials in RA and type I diabetes have been carried out and other trials are in progress or are imminent. In this review, we provide an update on tolDC therapy, in particular in relation to the treatment of RA, and discuss the challenges and the future perspectives of this new experimental immunotherapy.

Efficacy and safety of different doses and retreatment of rituximab: a randomised, placebo-controlled trial in patients who are biological naive with active rheumatoid arthritis and an inadequate response to methotrexate (Study Evaluating Rituximab's Efficacy in MTX iNadequate rEsponders (SERENE)).

OBJECTIVES: This phase III study evaluated the efficacy and safety of rituximab plus methotrexate (MTX) in patients with active rheumatoid arthritis (RA) who had an inadequate response to MTX and who were naïve to prior biological treatment. METHODS: Patients with active disease on stable MTX (10-25 mg/week) were randomised to rituximab 2 x 500 mg (n=168), rituximab 2 x 1000 mg (n=172), or placebo (n=172). From week 24, patients not in remission (Disease Activity Score (28 joints) > or =2.6) received a second course of rituximab; patients initially assigned to placebo switched to rituximab 2 x 500 mg. The primary end point was American College of Rheumatology 20 (ACR20) response at week 24. All patients were followed until week 48. RESULTS: At week 24, both doses of rituximab showed statistically superior efficacy (p<0.0001) to placebo (ACR20: 54%, 51% and 23%; rituximab (2 x 500 mg) + MTX, rituximab (2 x 1000 mg) + MTX and placebo + MTX, respectively). Secondary end points were also significantly improved for both rituximab groups compared with placebo. Further improvements in both rituximab arms were observed from week 24 to week 48. Rituximab + MTX was well tolerated, demonstrating comparable safety to placebo + MTX through to week 24, and between rituximab doses through to week 48. CONCLUSIONS: Rituximab (at 2 x 500 mg and 2 x 1000 mg) plus MTX significantly improved clinical outcomes at week 24, which were further improved by week 48. No significant differences in either clinical or safety outcomes were apparent between the rituximab doses.

Atacicept, a novel B cell-targeting biological therapy for the treatment of rheumatoid arthritis.

BACKGROUND: Recent data suggest a key role for B cells in the pathogenesis of many autoimmune diseases including rheumatoid arthritis (RA), and biological therapies targeting B cells are promising treatments for patients with RA. Atacicept inhibits B cell maturation, differentiation and survival, and immunoglobulin production by depriving B cells of growth and development signals. Therefore, atacicept may represent an effective strategy in RA treatment. OBJECTIVE: To evaluate the potential value of atacicept in RA treatment based on preclinical and clinical studies. METHODS: Preclinical and clinical data on atacicept were identified using PubMed and systematically reviewed. RESULTS/CONCLUSION: Preclinical and clinical studies show that atacicept is well tolerated, with no increased incidence of infections. Atacicept displays non-linear pharmacokinetics, with a more than dose-proportional increase in free drug and less than dose-proportional, saturated increase in atacicept-ligand complex. Overall, the pharmacokinetic profiles of atacicept were consistent, dose-related and predictable. Dose-dependent reductions in immunoglobulins and other biomarkers, including rheumatoid factor, occurred rapidly but returned to baseline after discontinuation. There was a biphasic response in B cell number, but no effect on other leucocytes. Atacicept improved the signs and symptoms of RA, although larger studies are needed to confirm its efficacy and its optimal use.

Thymic function in juvenile idiopathic arthritis.

OBJECTIVE: Thymic function declines exponentially with age. Impaired thymic function has been associated with autoimmune disease in adults but has never been formally assessed in childhood autoimmunity. Therefore, thymic function in children with the autoimmune disease juvenile idiopathic arthritis (JIA) was determined. METHODS: Thymic function was measured in 70 children and young adults with JIA (age range 2.1-30.8 (median 10.4)) and 110 healthy age-matched controls using four independent assays. T cell receptor excision circles (WBLogTREC/ml) and the proportion of CD4(+) CD45RA(+)CD31(+) T cells (representing recent thymic emigrants; %RTEs) were quantified and intrathymic proliferation measured by calculating the alphaTREC/SigmabetaTREC ratio. Lastly, regulatory T cells (T(Reg)) of thymic origin (CD4(+)FOXP3(+)) were quantified in peripheral blood to assess the ability of the thymus in JIA to generate this T cell subset. RESULTS: Thymic function was equivalent by all four parameters in JIA when compared with the control population. Furthermore, there was no consistent effect of JIA subtype on thymic function, although intrathymic proliferation was higher in the small rheumatoid factor (RF)(+) polyarticular group. There were no significant effects of disease-modifying antirheumatic drugs (DMARDs) or oral corticosteroids on thymic function, although those with the worst prognostic ILAR (International League of Associations for Rheumatology) subtypes were also those most likely to be on a DMARD. CONCLUSIONS: It is demonstrated that children and young adults with JIA, unlike adults with autoimmune diseases, have thymic function that is comparable with that of healthy controls. The varied pathologies represented by the term "JIA" suggest this observation may not be disease specific and raises interesting questions about the aetiology of thymic impairment in adult autoimmunity.

Determination of thymic function directly from peripheral blood: a validated modification to an established method.

The thymus contributes naïve, self MHC reactive, self tolerant T cells to the peripheral immune system throughout life, albeit with a log-linear decline with age. Quantification of thymic function is clinically relevant in the setting of lymphoablation, but a phenotypic marker distinguishing recent thymic emigrants from long lived naïve T cells remains elusive. T cell receptor excision circles (TREC) are present in thymocytes exiting the thymus and quantification of the most frequent of these, the deltarec-psiJalpha rearrangement has been widely used as a measure of recent thymic function. However, interpretation of results presented as TREC per cell has been criticised on the basis that extra-thymic cellular proliferation impacts on peripherally determined TREC numbers. TREC/ml is now considered to be more representative of thymic function than TREC/cell, especially where significant cellular proliferation occurs (e.g. during reconstitution following stem cell transplantation). Here we describe the validation of a novel variation to the established assay, directly quantifying TREC/ml from 300 microl whole blood. We show the assay to be reproducible, robust and stable longitudinally and we show equivalence of performance when compared with more standard assays. This assay particularly lends itself to the measurement of thymic function in children and where monitoring clinical variables is limited by tissue availability.

Therapeutic T-cell manipulation in rheumatoid arthritis: past, present and future.

Accumulating evidence suggests that RA is a T-cell-mediated autoimmune disease. Early attempts at disease modulation using strategies such as CD4 mAbs were severely hampered by a lack of biomarkers of autoreactivity. Recently, however, co-stimulation blockade has emerged as an effective treatment for RA. Alongside a greatly improved mechanistic understanding of immune regulation, this has rekindled hopes for authentic and robust immune programming. The final pieces of the jigsaw are not yet in place for RA but, in other disciplines, emerging treatment paradigms such as non-mitogenic anti-CD3 mAbs, autoantigenic peptides and even cellular therapies are providing hope for a future in which immunopathology can be specifically and vigorously curtailed.

A pilot study of combination anti-cytokine and anti-lymphocyte biological therapy in rheumatoid arthritis.

BACKGROUND: Immunological tolerance in humans using anti-T-cell monoclonal antibodies (mAbs) may be hampered by a pro-inflammatory microenvironment. All clinical trials of such therapies in rheumatoid arthritis (RA), however, have selected patients with active disease at baseline. Concurrent neutralization of inflammation with a TNFalpha antagonist should maximize the potential of anti-T-cell mAbs to induce tolerance in RA. AIM: To evaluate the safety of combining a TNFalpha antagonist and CD4 mAb in RA. DESIGN: An iterative pilot study focused on the safety of such combination therapy. METHODS: Eight poor prognosis, seropositive RA patients were treated with combined CD4 and TNFalpha blockade. Prolonged CD4 blockade was achieved with a humanized mAb, and TNFalpha blockade with a p55 TNF receptor fusion protein. RESULTS: There was a low incidence of classical first-dose reactions to the CD4 mAb, possibly reflecting concomitant TNFalpha blockade. An unusual anaphylactoid reaction was seen, however, and one patient developed a probable allergic reaction after several infusions. Skin rashes were common, as previously reported with CD4 mAb monotherapy. No serious infections were documented during follow-up, despite CD4+ lymphopenia in some patients. Most patients appeared to demonstrate improved RA disease control after the study. After 17-49 months after therapy, one patient was in remission, one remained off disease modifying anti-rheumatic drugs and five had stable disease, three on previously ineffective doses of methotrexate. CONCLUSION: We report, for the first time in man, immunotherapy with a combination of an anti-cytokine and an anti-T-cell reagent. We witnessed an unusual first-dose reaction but there were no significant infectious complications.

Abnormal T cell differentiation persists in patients with rheumatoid arthritis in clinical remission and predicts relapse.

OBJECTIVES: An abnormal CD4+ T cell subset related to inflammation exposure (inflammation-related cells, IRC) has been identified in rheumatoid arthritis (RA). Patients with inflammatory and non-inflammatory diseases were used to examine the relationship between inflammation and this T cell subset in vivo. METHODS: Blood was collected from healthy controls and patients with RA (active disease or in clinical remission), Crohn's disease and osteoarthritis. IRC and chemokine receptors were quantified by flow cytometry. Thymic activity and apoptotic factors were measured by real-time polymerase chain reaction. Circulating cytokines were measured by enzyme-linked immunosorbent assay. CXCR4 and SDF1 in synovial biopsies were measured using immunohistochemistry. RESULTS: IRC were identified in patients with RA (p<0.0001) and Crohn's disease (p = 0.005), but not in those with osteoarthritis. In RA in remission, IRC persisted (p<0.001). In remission, hyperproliferation of IRC was lost, chemokine receptor expression was significantly lowered (p<0.007), Bax expression dropped significantly (p<0.001) and was inversely correlated with IRC (rho = -0.755, p = 0.03). High IRC frequency in remission was associated with relapse within 18 months (OR = 6.4, p<0.001) and a regression model predicted 72% of relapse. CONCLUSIONS: These results suggest a model in which, despite the lack of systemic inflammation, IRC persist in remission, indicating that IRC are an acquired feature of RA. They have, however, lost their hyper-responsiveness, acquired a potential for survival, and no longer express chemokine receptors. IRC persistence in remission confirms their important role in chronic inflammation as circulating precursors of pathogenic cells. This was further demonstrated by much higher incidence of relapse in patients with high IRC frequency in remission.

The role of the cellular prion protein in the immune system.

Prion protein (PrP) plays a key role in the pathogenesis of prion diseases. However, the normal function of the protein remains unclear. The cellular isoform (PrP(C)) is expressed widely in the immune system, in haematopoietic stem cells and mature lymphoid and myeloid compartments in addition to cells of the central nervous system. It is up-regulated in T cell activation and may be expressed at higher levels by specialized classes of lymphocyte. Furthermore, antibody cross-linking of surface PrP modulates T cell activation and leads to rearrangements of lipid raft constituents and increased phosphorylation of signalling proteins. These findings appear to indicate an important but, as yet, ill-defined role in T cell function. Although PrP(-/-) mice have been reported to have only minor alterations in immune function, recent work has suggested that PrP is required for self-renewal of haematopoietic stem cells. Here, we consider the evidence for a distinctive role for PrP(C) in the immune system and what the effects of anti-prion therapeutics may be on immune function.

Early rheumatoid arthritis is associated with a deficit in the CD4+CD25high regulatory T cell population in peripheral blood.

OBJECTIVE: Our aim was to test the hypothesis that there is a deficit in the CD4+CD25high regulatory T-cell population in early rheumatoid arthritis (RA), either in size or functional activity. METHODS: Peripheral blood mononuclear cells were examined from subjects with early active RA who had received no previous disease-modifying therapy (n = 43), from individuals with self-limiting reactive arthritis (n = 14), from subjects with stable, well-controlled RA (n = 82) and from healthy controls (n = 72). The frequencies of CD4+CD25high T-cells were quantified using flow cytometry, and function was assessed by the ability to suppress proliferation of CD4+CD25- T-cells. Paired blood and synovial fluid was analysed from a small number of RA and reactive arthritis patients. RESULTS: There was a smaller proportion of CD4+CD25high T-cells in the peripheral blood of early active RA patients (mean 4.25%) than in patients with reactive arthritis or in controls (mean 5.90 and 5.30%, respectively, P = 0.001 in each case). Frequencies in stable, well-controlled RA (mean 4.63%) were not significantly different from early active RA or controls. There were no differences in suppressor function between groups. Higher frequencies of CD4+CD25high T-cells were found in synovial fluid than blood in both RA and reactive arthritis. CONCLUSIONS: These data demonstrate a smaller CD4+CD25high regulatory T-cell population in peripheral blood of individuals with early active RA prior to disease-modifying treatment. This may be a contributory factor in the susceptibility to RA and suggests novel approaches to therapy.