Pôster:

Abatacept (ABA) can reduce gamma-globulin levels and specific autoantibodies, but there is no data on anti-vimentin (anti-MCV) and information about anti-cyclic citrullinated peptide (anti-CCP) is conflicting, especially for long-term evaluation. The objective was to assess prospectively the long-term effect on gamma-globulins and autoantibodies of ABA in comparison to tumour necrosis factor inhibitors (TNFi) in rheumatoid arthritis (RA) patients.

Materials and methods

Eighteen RA patients undergoing abatacept(ABA-RA) and 18 age/sex-matched patients treated with TNFi (TNFi-RA) were compared regarding clinical, inflammatory data, total and specific (IgG, IgM, IgA) gamma-globulins, free light chains (FLC), IgG and IgM rheumatoid Factor (RF), anti-MCV and anti-CCPIII, assessed before and every 6 months, up to 24 months, with a systematic infectious screening protocol. Exclusion criteria: previous abatacept/rituximab or low gamma-globulin (<0.7g/dL).

Results

At baseline, female sex (78vs.78%), medians of age (55vs.53years), DAS28 (5.7vs.5.7), levels of gamma-globulin (1.4vs.1.35g/dL), IgG (1,168vs.1,079mg/dL), IgM (107vs.113mg/dL), IgA (333vs.322mg/dL), kappa (342vs.249mg/dL), lambda (170vs.150mg/dL), IgG-RF (63vs.25UI), IgM-RF (76vs.53UI), anti-CCPIII (216vs.189UI), and anti-MCV (202vs.102UI) were comparable (p>0.05). After 6 months and during the follow up, disease activity parameters improved similarly in both groups (p>0.05). In ABA-RA, at 6 months, remarkable decreases were observed in total gamma-globulin (1.4vs.1.05g/dL), IgG (1,168vs.997), IgA (333vs.278mg/dL), kappa (342vs.257mg/dL), lambda (170vs.144mg/dL), IgG-RF (63vs.24UI), IgM-RF (76vs.37UI), anti-CCPIII (216vs.183UI), and anti-MCV (202vs.65UI) in comparison to baseline (p<0.05) and in contrast to TNFi-RA which showed no decrease in any of these parameters (p>0.05), despite of similar disease activity control. Longitudinal measurements in ABA-RA demonstrated that levels of immunoglobulins remained mostly stable for subsequent evaluations, up to 24 months (p>0.05), but ABA-RA had more often transient IgG levels under the lower limit of normality (66.7%vs.33.3%,p=0.046) and one patient had an isolated IgG level <600mg/dL. No severe infection occurred. Regarding autoantibodies, further longitudinal reductions were seen in the 12th month for IgM-RF and in the 18th month for anti-MCV, which was lost by 24 months. Despite the decrease in autoantibodies titles, significant changes in sorologic status (immunologic remission) were not observed. Of note, only in ABA-RA group, patients who achieved low disease activity (DAS<3.2) after 6 months (n=6;33%) had higher baseline levels of IgG-RF[208(70-653)vs.25(5-120);p=0.003] and IgM-RF[143(108-807)vs.20(2-142);p=0.006] compared to those who did not.

Conclusion

These comparative data demonstrate that ABA induces a long-term and non-progressive reduction in gamma-globulin and autoantibodies levels, including anti-CCPIII and anti-MCV, regardless of disease activity control, but not associated with increased infection rate or disappearance of serologic status.