Comparison of efficacy of the tumour necrosis factor alpha blocking agents Etanercept and Infliximab in patients with active rheumatoid arthritis

Background: Tumor necrosis factor (TNF) antagonists are biologic response modifiers that have significantly improved the outcomes in patients with rheumatoid arthritis (RA). The first two agents designed to modify the biologic effects of TNF alpha have been infliximab and etanercept. Objectives: The aim of our work was to evaluate differences between the two agents, in terms of clinical efficacy and the rapidity of onset of action, using the American college of Rheumatology criteria ACR 20, 50 and 70, and the improvement of quality of live using the Health assessment questionnaire (HAQ). Methods: We selected 32 patients with RA with an incomplete response to DMARDs, and randomly assigned them to one of the following treatment groups: a first group received twice weekly subcutaneous etanercept at a dosage of 25mg. The second group received Infliximab i.v. at 3mg/kg at 0, 2, 6, 8 weeks. Both group received a stable dose of methotrexate (10 -12,5 mg/week). We evaluated the efficacy after 14- 22-54 weeks of treatment. Results: After 14 weeks, the 54.4% of patients were considered ACR-responders in the etanercept group, whereas in the infliximab group the percentage of responders was 74.4%: all the core set variables show an improvement, but infliximab gives better results for the tender joint count (TJC score) (p = 0,004) and for physicians global assessment (p = 0,009). After 22 weeks, no significant difference between the two groups was present. After 54 weeks, etanercept results more effective than infliximab for TJC value (p = 0,018), for visual analogue scale for pain score (p = 0,01), for global disease assessment value (p = 0.003), with 74.4% of patients considered ACR-responders in the group treated with etanercept and 60% in the group treated with infliximab. As regards HAQ, patients in the infliximab group present higher scores at the weeks 14 but in the 22nd and 54th week patient in the etanercept group show better results. Conclusion: Our data show that both infliximab and etanercept have an established efficacy in RA, but the timing is different: infliximab leads to a rapid relief of symptoms and improvement of global status, resulting more efficacious than etanercept in 14th week. Vice versa, in 54th week is etanercept the most efficacious drug. Physicians now have two new weapons in the treatment armamentarium for patients with RA, with the same action but distinct clinical, pharmacokinetic and pharmacodynamic properties, and that can be used, for example, sequentially, starting with the drug with the most rapid onset of action to switch then to the one with an effectiveness staying on time. References: 1. Schwartzman S, Fleischmann R, Morgan GJ Jr. Do anti-TNF agents have equal efficacy in patients with rheumatoid arthritis? Arthritis Res Ther. 2004;6 Suppl 2:S3-S11. Epub 2004 Jun 21. 2. Hochberg MC, Tracy JK, Hawkins-Holt M, Flores RH. Comparison of the efficacy of the tumour necrosis factor alpha blocking agents adalimumab, etanercept, and infliximab when added to methotrexate in patients with active rheumatoid arthritis. Ann Rheum Dis. 2003 Nov;62 Suppl 2:ii13-6. 3. Mikuls TR, Moreland LW. TNF blockade in the treatment of rheumatoid arthritis: infliximab versus etanercept. Expert Opin Pharmacother. 2001 Jan;2(1):75-84.