THU0117 Abatacept can demonstrate maximum efficacy without background methotrexate treatment in rheumatoid arthritis
Authors: N. Takahashi, T. Kojima, K. Funahashi, D. Kato, H. Matsubara, Y. Hattori, N. Ishiguro
Journal: Annals of the Rheumatic Diseases (2013)

<h3>Background</h3> Abatacept (ABT), a selective co-stimulation modulator, is the first in a new class of biologic agents for the treatment of rheumatoid arthritis (RA) that inhibits T cell activation by binding to CD80/86, and modulating its interaction with CD28. Some other biologic agents have been reported to require concomitant methotrexate (MTX) treatment to maximize their clinical efficacy while there have been only few data about ABT. Although they reported that the efficacy in the patients receiving ABT monotherapy was comparable to that seen in patients receiving background DMARD in the ARRIVE trial [1], they did not compare directly between the patients taking ABT monotherapy and with background MTX. <h3>Objectives</h3> We studied whether background MTX treatment increased the ABT efficacy or not, by using data from Japanese multicenter registry system for RA patients taking biologic treatments. <h3>Methods</h3> All RA patients who underwent ABT treatment for at least 24 weeks (n=111) at Nagoya University Hospital and 12 other institutes (Tsurumai Biologics Communication Study Group [2]) were enrolled in this study. Demographic data at baseline and the following parameters of disease activity (tender joint count (TJC) and swollen joint count (SJC) on 28 joints, patient global assessment (VAS), ESR, and serum CRP and MMP-3 levels during 24 weeks. We compared these clinical data between the patients treated without concomitant MTX (ABT mono, n=44) and those treated with concomitant MTX (ABT+MTX, n=67, mean MTX dose of 7.4 mg/week). The last observation carried forward (LOCF) method was used in each analysis. <h3>Results</h3> In the baseline characteristic data, ABT mono group showed significantly higher mean patient age (65.5 and 61.6, p&lt;0.01) compared to ABT+MTX group while no other parameters showed significant difference including RA disease duration (11.6 and 9.8 years) and the all disease activity indices such as DAS28 (4.5 and 4.6), ESR (53.4 and 52.2 mm/h), and CRP (2.4 and 2.3 mg/dL). As shown in Fig. A-1 and Fig. A-2, both ABT mono and ABT+MTX group showed significant decreasing of DAS28 and SJC at week 4 compared to the baseline and further decreasing were seen at week 24. There was no significant difference between these two groups at any time point. When we compared the percentage of patients who achieved low disease activity (DAS28&lt;3.2) or clinical remission (DAS28&lt;2.6) we found no significant difference between ABT mono and ABT+MTX group (Fig. B-1 and Fig. B-2). Importantly, concomitant MTX usage did not demonstrate any additional decreasing of disease activity at any time point. <h3>Conclusions</h3> The abatacept treatment in the patients without concomitant MTX demonstrated the equivalent efficacy compared to the patients with MTX. Abatacept seems not to require the background MTX treatment to maximize the drug efficacy. Abatacept would be good treatment option in the patients with high risk factors for MTX usage, such as pulmonary or renal involvements. <h3>References</h3> Ann Rheum Dis 2009;68:1708 Mod Rheumatol. 2011 Sep 3. [Epub ahead of print] <h3>Disclosure of Interest</h3> N. Takahashi: None Declared, T. Kojima Speakers Bureau: Abbott Japan, Chugai Pharmaceutical, Eisai, Mitsubishi Tanabe Pharma, Pfizer Japan, Takeda Pharmaceutical, Bristol-Myers Squibb, K. Funahashi: None Declared, D. Kato: None Declared, H. Matsubara: None Declared, Y. Hattori: None Declared, N. Ishiguro Speakers Bureau: Abbott Japan, Chugai Pharmaceutical, Eisai, Mitsubishi Tanabe Pharma, Pfizer Japan, Takeda Pharmaceutical, Bristol-Myers Squibb