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 in effectiveness of ABT treatment have not been understood.
Objectives The objective of this retrospective study is to analyze the patients’ characteristics of RA patients who are treated with ABT with rapid effectiveness.
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) was over 3.2 at initiation of ABT and below 3.2 at 24 weeks. Patients in whom early improvement rate of DAS28 (=delta DAS28 from 0w to 4w/delta DAS28 from 0w to 24w) was over 50% were called rapid effectiveness group (RG, n=14) and patients in whom early improvement rate was below 50% were called slow effectiveness group (SG, n=14). Patients’ characteristics at baseline were compared between two groups.
Results Mean DAS28 were 4.59(0w), 2.89(4w), 2.50(12w), 2.25(24w) in RG and 4.20(0w), 3.92(4w), 3.05(12w), 2.57(24w) in SG. There was a significant difference between two groups at only 4w. 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 was 85.7% in RG and 35.7% in SG (p=0.018). Serum immune globulin G (IgG) value at initiation of ABT was 1672mg/dl in RG and 1332mg/dl in SG (p=0.035). There was a tendency of difference in MTX usage (78.6% in RG, 35.7% in SG) and RA duration (8.8 y in RG, 12.6y in SG).
Conclusions This study showed that previous biologics treatment might affects immunological condition in patients with RA and that might result in the differences in effectiveness speed of ABT. This study 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-cell), function of B-cells is influenced by function of T-lymphocytes (T-cell). Serum IgG shows the function of T-cells indirectly and effectiveness in ABT treatment may be rapid in RA patients with increased function of T-cells compared with in patients with decreased function of T-cells.
Sciff M et al. Efficacy and safety of abatacept or infliximab vs placebo in ATTEST: a phase III, multi-centre, 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 Syst Rev. 2011; 2: CD008794.
Disclosure of Interest None Declared
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