BackgroundSeveral agents provide treatment for established rheumatoid arthritis (RA), but a crucial therapeutic goal is to delay/prevent progression of undifferentiated arthritis (UA) or very early RA.ObjectiveTo determine the impact of T-cell costimulation modulation in patients with UA or very early RA.MethodsIn this double-blind, phase II, placebocontrolled, 2-year study, anti-cyclic citrullinated peptide (CCP)2-positive patients with UA (not fulfilling the ACR criteria for RA) and clinical synovitis of two or more joints were randomised to abatacept (∼10 mg/kg) or placebo for 6 months; the study drug was then terminated. The primary end point was development of RA (by ACR criteria) at year 1. Patients were monitored by radiography, MRI, CCP2, rheumatoid factor and 28 joint count Disease Activity Score (DAS28) over 2 years.ResultsAt year 1, 12/26 (46%) abatacept-treated versus 16/24 (67%) placebo-treated patients developed RA (difference (95% CI) −20.5% (−47.4% to 7.8%)). Adjusted mean changes from baseline to year 1 in Genant-modified Sharp radiographic scores for abatacepttreated versus placebo-treated patients, respectively, were 0 versus 1.1 for total score, and 0 versus 0.9 for erosion score. Mean changes from baseline to year 1 in MRI erosion, osteitis and synovitis scores were 0, 0.2 and 0.2, respectively, versus 5.0, 6.7 and 2.3 in the abatacept versus placebo groups. Safety was comparable between groups; serious adverse events occurred in one patient (3.6%) in each group.ConclusionAbatacept delayed progression of UA/very early RA in some patients. An impact on radiographic and MRI inhibition was seen, which was maintained for 6 months after treatment stopped. This suggests that it is possible to alter the progression of RA by modulating T-cell responses at a very early stage of disease.Trial registration numberNCT00124449.

Objective:Assess the effect of abatacept on progression of structural damage over 2 years in patients with rheumatoid arthritis who had an inadequate response to methotrexate.Methods:539 patients entered an open-label extension of the AIM (Abatacept in Inadequate responders to Methotrexate) trial and received abatacept. Radiographic assessment of the hands and feet was performed at baseline, year 1 and year 2. At year 2, each patient’s radiographs were scored for progression blinded to sequence and treatment allocation.Results:In patients treated with abatacept for 2 years, greater reduction in progression of structural damage was observed in year 2 than in year 1. The mean change in total Genant-modified Sharp scores was reduced from 1.07 units in year 1 to 0.46 units in year 2. Similar reductions were observed in erosion and joint space narrowing scores. Following 2 years of treatment with abatacept, 50% of patients had no progression of structural damage as defined by a change in the total score of ⩽0 compared with baseline. 56% of patients treated with abatacept had no progression during the first year compared with 45% of patients treated with placebo. In their second year of treatment with abatacept, more patients had no progression than in the first year (66% vs 56%).Conclusions:Abatacept has a sustained effect that inhibits progression of structural damage. Furthermore, the mean change in radiographic progression in patients treated with abatacept for 2 years was significantly lower in year 2 versus year 1, suggesting that abatacept may have an increasing disease-modifying effect on structural damage over time.

Polyclonal CD4+ T cell activation is characteristic of spontaneous lupus. As a potential explanation for this phenotype, we hypothesized that T cells from lupus-prone mice are intrinsically hyperresponsive to stimulation with antigen, particularly to those peptide ligands having a low affinity for the T cell receptor (TCR). To test this hypothesis, we backcrossed the α and β chain genes of the AND TCR specific for amino acids 88–104 of pigeon cytochrome C (PCC) to the Fas-intact MRL/Mp+ Fas-lpr and to the H-2k–matched control backgrounds B10.BR and CBA/CaJ (MRL.AND, B10.AND, and CBA.AND, respectively), and assessed naive CD4+ TCR transgenic T cell activation in vitro after its encounter with cognate antigen and lower affinity altered peptide ligands (APLs). MRL.AND T cells, compared with control B10.AND and CBA.AND cells, proliferated more when stimulated with agonist antigen. More strikingly, MRL.AND T cells proliferated significantly more and produced more interleukin 2 when stimulated with the APLs of PCC 88–104, having lower affinity for the transgenic TCR. These results imply that one of the forces driving polyclonal activation of α/β T cells in lupus is an intrinsically heightened response to peptide antigen, particularly those with low affinity for the TCR, independent of the nature of the antigen-presenting cell and degree of costimulation.

Objectives: Abatacept is the only agent currently approved to treat rheumatoid arthritis (RA) that targets the co-stimulatory signal required for full T-cell activation. No studies have been conducted on its effect on the synovium, the primary site of pathology. The aim of this study was to determine the synovial effect of abatacept in patients with RA and an inadequate response to tumour necrosis factor alpha (TNFa) blocking therapy. Methods: This first mechanistic study incorporated both dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and arthroscopy-acquired synovial biopsies before and 16 weeks after therapy, providing tissue for immunohistochemistry and quantitative real-time PCR analyses. Results: Sixteen patients (13 women) were studied; all had previously failed TNFa-blocking therapy. Fifteen patients completed the study. Synovial biopsies showed a small reduction in cellular content, which was significant only for B cells. The quantitative PCR showed a reduction in expression for most inflammatory genes (Wald statistic of p,0.01 indicating a significant treatment effect), with particular reduction in IFNc of 252% (95% CI 273 to 215, p,0.05); this correlated well with MRI improvements. In addition, favourable changes in the osteoprotegerin and receptor activator of nuclear factor kappa B levels were noted. DCE-MRI showed a reduction of 15-40% in MRI parameters. Conclusion: These results indicate that abatacept reduces the inflammatory status of the synovium without disrupting cellular homeostasis. The reductions in gene expression influence bone positively and suggest a basis for the recently demonstrated radiological improvements that have been seen with abatacept treatment in patients with RA.Understanding of disease pathogenesis in rheumatoid arthritis (RA) has led to novel approaches in targeted drug development. Despite the demonstrated success of tumour necrosis factor (TNF) antagonists, up to 50% of patients have an inadequate response to TNF blockade therapy. [1][2][3][4] This observation has fuelled the search for alternative targeted approaches.Abatacept is a recombinant fusion protein comprising the extracellular domain of human cytotoxic T-lymphocyte antigen 4 and a fragment of the Fc domain of human IgG1. It acts by competing with CD28 for binding to CD80/CD86, modulating the second co-stimulatory signal required for full T-cell activation. 6Abatacept has demonstrated benefits in patients with RA and an inadequate response to methotrexate 7 that are comparable to those observed in studies of TNF blockade, with efficacy also confirmed in the particularly resistant group of patients who have failed TNF blockade therapy. 8There is limited information on the impact of costimulation modulation on the synovium. The objective of this first mechanistic study was to determine the synovial effect of abatacept in a TNF antagonist-resistant group of patients. A novel and validated method of gene expression analysis was employed in combination with immunohistochemistry to eval...

The effect of abatacept, a selective T-cell co-stimulation modulator, on vaccination has not been previously investigated. In this open-label, single-dose, randomized, parallel-group, controlled study, the effect of a single 750 mg infusion of abatacept on the antibody response to the intramuscular tetanus toxoid vaccine (primarily a memory response to a T-celldependent peptide antigen) and the intramuscular 23-valent pneumococcal vaccine (a less T-cell-dependent response to a polysaccharide antigen) was measured in 80 normal healthy volunteers. Subjects were uniformly randomized to receive one of four treatments: Group A (control group), subjects received vaccines on day 1 only; Group B, subjects received vaccines 2 weeks before abatacept; Group C, subjects received vaccines 2 weeks after abatacept; and Group D, subjects received vaccines 8 weeks after abatacept. Anti-tetanus and antipneumococcal (Danish serotypes 2, 6B, 8, 9V, 14, 19F and 23F) antibody titers were measured 14 and 28 days after vaccination. While there were no statistically significant differences between the dosing groups, geometric mean titers following tetanus or pneumococcal vaccination were generally lower in subjects who were vaccinated 2 weeks after receiving abatacept, compared with control subjects. A positive response (defined as a twofold increase in antibody titer from baseline) to tetanus vaccination at 28 days was seen, however, in ≥ 60% of subjects across all treatment groups versus 75% of control subjects. Similarly, over 70% of abatacept-treated subjects versus all control subjects (100%) responded to at least three pneumococcal serotypes, and approximately 25-30% of abatacept-treated subjects versus 45% of control subjects responded to at least six serotypes.