Background Abatacept (ABT) is an effective biological agent which has unique mechanism to reduce disease activity of rheumatoid arthritis (RA). Although good continuation rate and safety in ABT treatment was reported, ABT treatment has a tendency that response of drug was relatively delayed, what we call the slow starter [1, 2]. However, rapid effectiveness with ABT treatment is seen in some RA patients in clinical setting and the factors influencing the rapidness of effectiveness of ABT treatment have not been well understood.
Objectives The objectives of this retrospective study is to analyze the patients’ characteristics of RA patients treated with ABT with rapid effectiveness using Japanese multicenter registry system (TBC).
Methods A Japanese multicenter registry database for biological treatment in RA patients (TBC) was used in this study. This study utilized RA patients who continued ABT for 24 weeks and in whom disease activity score 28 using CRP (DAS28-CRP) was over 3.2 at initiation of ABT and below 3.2 at 24 weeks (responders). Patients in whom early improvement rate of DAS28 (=delta DAS28 from 0w to 4w/delta DAS28 from 0w to 24w) was over 0.5 were called rapid effectiveness group (RG, n=35) and patients in whom early improvement rate was below 0.5 were called slow effectiveness group (SG, n=38). Patients’ characteristics at baseline were compared between two groups.
Results Mean DAS28 were 4.69(0w), 3.03(4w), 2.79(12w), 2.43(24w) in RG and 4.58(0w), 4.10(4w), 3.24(12w), 2.45(24w) in SG. There was a significant difference between two groups at 4w and 12w. There were no significant differences between two groups in age, RA duration, rheumatoid factor level and baseline disease activity evaluated using DAS28, SDAI, CDAI, CRP, ESR and MMP-3. The rate of bio-naive which meant ABT was first biologics was 77.1% (27 cases) in RG and 55.3% (21 cases) in SG (p=0.049). Mean serum immune globulin G (IgG) value at initiation of ABT was 1731mg/dl in RG and 1420mg/dl in SG (p=0.078). The rate of concomitant methotrexate (MTX) was 62.9% (22 cases) in RG and 39.5% (15 cases) in SG.
Conclusions This study suggests that previous biologics treatment may affects immunological condition in patients with RA and that may result in the differences in effectiveness speed of ABT. This study also showed that serum IgG level at baseline was one of the predictive factors of rapid effectiveness in ABT treatment. Although IgG is secreted from B-lymphocytes (B-cells), function of B-cells is influenced by the activity of T-lymphocytes (T-cells). Serum IgG shows the activity of T-cells indirectly and effectiveness in ABT treatment may be rapid in RA patients with increased actuvity of T-cells compared with in patients with decreased activity of T-cells.
Sciff M et al. Efficacy and safety of abatacept or infliximab vs placebo in ATTEST: a phase III, multicentre, randomized, double-blind, placebo-controlled study in patients with rheumatoid arthritis and an inadequate response to methotrexate. Ann Rheum Dis. 2008; 67: 1096-1103.
Singh JA et al. Adverse effects of biologics: a network meta-analysis and Cochrane overview. Cochrane Database
Disclosure of Interest None Declared