Objective:To validate and compare the definition of the Disease Activity Score 28 based on C-reactive protein (DAS28 (CRP)) to the definition based on erythrocyte sedimentation rate (ESR).Methods:Data were analysed from two randomised, double-blind, placebo-controlled trials of abatacept of 6-month and 12-month duration in patients with rheumatoid arthritis. European League Against Rheumatism (EULAR) response criteria and the proportion of patients in remission (DAS28 <2.6) based on the two DAS28 definitions were examined. Trends in radiographic progression (erosion score, joint space narrowing score and total score) and physical function (Health Assessment Questionnaire Disability Index (HAQ-DI)) across the EULAR responder states (none, moderate and good) were analysed.Results:There was general agreement in determining the EULAR responder state using both DAS28 definitions (κ = 0.80, 95% CI 0.76 to 0.83). Overall, there was 82.4% agreement on the EULAR response criteria; when disagreements occurred, the DAS28 (CRP) yielded a better EULAR response more often then DAS28 (ESR) (12.6% vs 4.9%, respectively). There was also agreement in determining remission: κ = 0.69 (95% CI 0.60 to 0.78). Radiographic progression decreased in patients treated with abatacept across EULAR states (from none to moderate to good) based on both definitions. For patients treated with placebo, the trend was not as pronounced, with radiographic scores higher for moderate vs non-responders. For physical function, similar trends were observed across the EULAR states for both DAS28 definitions.Conclusions:The DAS28 (CRP) has been validated against radiographic progression and physical function. While the DAS28 (CRP) yielded a better EULAR response more often than the DAS28 (ESR), the validation profile was similar to the DAS28 (ESR), indicating that both measures are useful for assessing disease activity in patients with rheumatoid arthritis.

ObjectiveTo compare the efficacy and safety of subcutaneous (SC) and intravenous (IV) abatacept.MethodsIn this phase IIIb double-blind, double-dummy, 6-month study, patients with rheumatoid arthritis (RA) and inadequate responses to methotrexate were randomized to receive 125 mg SC abatacept on days 1 and 8 and weekly thereafter (plus an IV loading dose [∼10 mg/kg] on day 1) or IV abatacept (∼10 mg/kg) on days 1, 15, and 29 and every 4 weeks thereafter. The primary end point for determining the noninferiority of SC abatacept to IV abatacept was the proportion of patients in each group meeting the American College of Rheumatology 20% improvement criteria (achieving an ACR20 response) at month 6. Other efficacy end points, immunogenicity, and safety were also assessed.ResultsOf 1,457 patients, 693 of 736 (94.2%) treated with SC abatacept and 676 of 721 (93.8%) treated with IV abatacept completed 6 months. At month 6, 76.0% (95% confidence interval 72.9, 79.2) of SC abatacept–treated patients versus 75.8% (95% confidence interval 72.6, 79.0) of IV abatacept–treated patients achieved an ACR20 response (estimated difference between groups 0.3% [95% confidence interval –4.2, 4.8]), confirming noninferiority of SC abatacept to IV abatacept. Onset and magnitude of ACR responses and disease activity and physical function improvements were comparable between the SC and IV abatacept–treated groups. The proportions of adverse events (AEs) and serious AEs over 6 months were 67.0% and 4.2%, respectively, in the SC abatacept–treated group and 65.2% and 4.9%, respectively, in the IV abatacept–treated group, with comparable frequencies of serious infections, malignancies, and autoimmune events between groups. SC injection site reactions (mostly mild) occurred in 19 SC abatacept (IV placebo)–treated patients (2.6%) and 18 IV abatacept (SC placebo)–treated patients (2.5%). Abatacept-induced antibodies occurred in 1.1% of SC abatacept–treated patients and 2.3% of IV abatacept–treated patients.ConclusionSC abatacept provides efficacy and safety comparable with that of IV abatacept, with low immunogenicity and high retention rates, consistent with the established IV abatacept profile. Rates of injection site reactions were low. SC abatacept will provide additional treatment options, such as an alternative route of administration, for patients with RA.

NCT00124982.

Objective. To assess the safety and efficacy of abatacept, a selective T cell costimulation modulator, in patients with psoriatic arthritis (PsA).Methods. In this 6-month, multicenter, randomized, double-blind, placebo-controlled, phase II study, 170 PsA patients with a psoriasis target lesion (TL) >2 cm who had previously taken disease-modifying antirheumatic drugs (DMARDs), including anti-tumor necrosis factor (anti-TNF) agents, were randomized (1:1: 1:1) to receive placebo or abatacept at doses of 3 mg/kg, 10 mg/kg, or 30/10 mg/kg (2 initial doses of 30 mg/kg, followed by 10 mg/kg) on days 1, 15, and 29 and then once every 28 days thereafter. The primary end point was the American College of Rheumatology 20% criteria for improvement (ACR20 response) on day 169. Other key end points were magnetic resonance imaging (MRI) scores for joint erosion, osteitis, and synovitis, scores on the Health Assessment Questionnaire (HAQ) and the Short Form-36 (SF-36) health survey, the investigator's global assessment of psoriasis, the TL score, and the Psoriasis Area and Severity Index (PASI) score.Results. Proportions of patients achieving an ACR20 response were 19%, 33%, 48%, and 42% in the placebo, the abatacept 3 mg/kg, the abatacept 10 mg/kg, and the abatacept 30/10 mg/kg groups, respectively. Compared with placebo, improvements were significantly higher for the abatacept 10 mg/kg (P ‫؍‬ 0.006) and 30/10 mg/kg (P ‫؍‬ 0.022) groups, but not for 3 mg/kg group (P ‫؍‬ 0.121). All abatacept regimens resulted in improved MRI, HAQ, and SF-36 scores, with 10 mg/kg showing the greatest improvements. Improvements in the TL and PASI scores were observed in all abatacept arms; a response according to the investigator's global assessment was seen only with 3 mg/kg of abatacept. The safety profiles were similar among the treatment arms.Conclusion. The results of this study suggest that 10 mg/kg of abatacept, the approved dosage for rheumatoid arthritis and juvenile idiopathic arthritis, may be an effective treatment option for PsA.Psoriatic arthritis (PsA) is a chronic inflammatory disease characterized by both arthritis and psoriasis ClinicalTrials.gov identifier: NCT00534313.

Objective. To evaluate the efficacy, radiographic changes, and safety of abatacept and methotrexate therapy through 2 years in a long-term extension of a previously published 1-year study.Methods. Patients who received placebo during year 1 were switched to abatacept. Patients taking abatacept continued to take it. Efficacy and safety were assessed through 2 years.Results. Of 539 patients enrolled in the initial 1-year study, 488 completed 1 year of the long-term extension (2% discontinued for lack of efficacy). .8% for the HAQ DI, and 9.7 versus 10.6 and 7.3 versus 7.2, respectively, for the mean change in the physical and mental components summary scores of the SF-36). In the abatacept group, post hoc analysis demonstrated further inhibition of radiographic progression during year 2 (57% reduction in mean change of total score in year 2 versus year 1; P < 0.0001), and minimal radiographic progression was observed (mean change in total score from baseline was 1.1 and 1.6 at year 1 and 2, respectively). Rates of adverse events (AEs) and severe AEs were consistent throughout the cumulative period.Conclusion. The improvements in signs and symptoms, physical function, and HRQOL observed after 1 year of abatacept treatment were maintained through 2 years of treatment. This durability was accompanied by a safety profile consistent with that in the double-blind portion of the study. Radiographic proClinicalTrials.gov identifier: NCT00048568.