Background Tumor necrosis factor alpha (TNFa) is a proinflammatory cytokine than its synthesis increases in patients with Rheumatoid Arthritis, promoting other proinflammatories cytokines and is associated with tenderness and swelling of joints. Etanercept is a DNA recombinant fusion protein, acting as a TNFa inhibitor.

Objectives To evaluate the efficacy and safety of Infinitam^® (biosimilar etanercept) compared with Enbrel^®(reference etanercept) after 12 and 24 weeks of treatment.

Methods This is a three treatment group randomized study: first and second group were in a PK sub population. First group received methotrexate plus biosimilar Etanercept 25 mg twice weekly (n=12) during 24 weeks. Second group initially received methotrexate plus reference Etanercept25 mg twice weekly (n=12) followed by 12 weeks with methotrexate plus biosimilar Etanercept 25 mg twice weekly. Third group received methotrexate plus biosimilar Etanercept 25 mg twice weekly (n=30) during 24 weeks. Primary end point was to evaluate the average on patients who achieved on the Disease Activity Score 28 joint assessment (DAS28) at weeks 12 and 24.

Results A total of 58 patients were randomized to groups 1, 2 and 3 (12; 12 and 34 respectively). Patients mean age was 47 years old, 91.2% female, and average of methotrexate dose was 12.3 mg/week. The average of DAS28 score at baseline was 6.4, 6.2, 5.9; as week 12: 3.1, 3.8, 3.7 and at 24 week 2.4, 2.7, 2.8 respectively A, B, and C group. None significant difference was observed in the pharmacokinetic groups (p=0.355). Serious adverse events ocurred in one patient of group 3

Conclusions Clinical response, procedures and observations at the end of treatment was as expected in all group of patients. Study drug safety was similar for both drugs. All patients improved DAS28 evaluations.

References Klareskog L, Van der Heijde D, de Pager JP, et al. Therapeutic effect of the combination of Etanercept and methotrexate compared with each treatment alone in patients with rheumatoid arthritis: double-blind randomized controlled trial. Lancet 2004;363:675-81. Kavanaughm A, Klareskog L, Van Der E. D, et al. Improvement in clinical response between 12 and 24 weeks in patients with rheumatoid arthritis on Etanercept therapy with or without methotrexate. Ann Rheum Dis 2008;67:1444-1447. Weinblatt ME, Kremer JM, Bankhurst AD, et al. A comparison of Etanercept, a recombinant tumor necrosis factor receptor: Fc fusion protein, in patients rheumatoid arthritis receiving methotrexate. N Engl J Med 1999;340:253-9. G Wells, JC Becker, J Teng, M Dougados, et al. Validation of the 28-joint Disease Activity Score (DAS28) and European League Against Rheumatism response criteria based on C-reactive protein against disease progression in patients with rheumatoid arthritis, and comparison with the DAS28 based on erythrocyte sedimentation rate. Ann Rheum Dis. 2009; 68(6): 954-960

Disclosure of Interest None Declared