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 3 mg/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 4 weeks thereafter for 18 weeks 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.