Good response to infliximab in rheumatoid arthritis following failure of interleukin-1 receptor antagonist

Aim: To evaluate the efficacy of tumor necrosis factor inhibitor infliximab in patients with rheumatoid arthritis (RA) who were disease-resistant to recombinant human interleukin-1 receptor antagonist (IL-1Ra). Methods: A total of 104 patients with active RA despite methotrexate (MTX) treatment were enrolled in the open trial. Among them, 27 IL-1Ra nonresponders Switchers' and 51 biologic-naive patients Naivers' received an infusion of 3mg/kg infliximab at weeks 0, 2, 6 and 14, combined with concurrent MTX therapy, while the other 26 patients who had never received any biologics Controls' continued MTX monotherapy. Clinical outcomes and safety were assessed at weeks 0, 2 and every 4weeks thereafter for 18weeks with the American College of Rheumatology (ACR) core set criteria, the Disease Activity Score in 28 joints, and records of adverse events (AEs) and abnormal laboratory findings. Results: At week 18, an ACR20 response was achieved in 56% of Switchers and 61% of Naivers, compared with 23% of Controls (P=0.0013 and 0.0126, respectively). Compared with Controls, both Switchers and Naivers achieved a significant improvement in tender-joint count, swollen-joint count, patient's assessment of pain, patient's and physician's global assessment of disease activity, erythrocyte sedimentation rate and C-reactive protein. Switchers even achieved a greater benefit from health assessment questionnaire (HAQ) scores than Naivers. Infliximab was well tolerated, with a similar incidence of AEs across all study groups. Conclusion: Switching from IL-1Ra to infliximab is effective in improving disease activity and maintaining joint function.