Secondary failure to treatment with recombinant human IL-1 receptor antagonist in Chinese patients with rheumatoid arthritis

The aim of this study is to assess the efficacy of anakinra, a recombinant human interleukin 1 receptor antagonist, plus methotrexate (MTX) in patients with active rheumatoid arthritis (RA) refractory to MTX therapy. A total of 54 patients with active RA, who were taking MTX at a stable dosage, were randomized to receive daily subcutaneous injections of anakinra (80 mg) or placebo. Clinical outcomes were assessed every 4 weeks for 24 weeks by using the criteria of the American College of Rheumatology. After 24 weeks, more patients achieved clinical benefits as determined by the ACR20 improvement treated with anakinra plus MTX compared with MTX alone (64% vs. 17%, P=0.004). In the anakinra group, an ACR50 response was observed in 38% and an ACR70 response in 17%. None of the patients treated with MTX alone achieved ACR50 or ACR 70 improvement. However, nine of 42 (21.4%) patients in the anakinra group, who showed therapeutic response initially, had secondary drug failure to anakinra therapy thereafter. A significant increase in mean DAS28 from baseline was found in the non-responders to anakinra compared with placebo (0.83 +/- 1.38 vs. -1.28 +/- 0.78, P<0.001). Anakinra is effective in the treatment of patients with active RA by blocking IL-1. However, the efficacy of anakinra is soon lost in about one fifth of patients in spite of initial good response.