Background The longterm use of adalimumab (ADL) is limited by the formation of neutralizing antibodies. To the best of our knowledge, immunogenicity in juvenile idiopathic arthritis (JIA) has not been investigates in depth.
Objectives Our main objective was to evaluate the prevalence of adalimumab immunogenicity in JIA and the association of anti-adalimumab antibodies (AAA) with response to treatment. Secondary objectives were to assess the association between AAA and ADL treatment time, and the influence of use of concomitant immunosuppressive therapy in the formation of AAA.
Methods Twenty consecutive patients with JIA treated with ADL >6 month participated in our cross-sectional study. The demographic and clinical characteristics, disease activity and use of methotrexate (MTX) were collected. Until now, were evaluated drugs levels (ELISA) and AAA (Brindgind ELISA) in ten of these patients, before the next injection. Serum samples with ADL concentrations >2mg/L were not analysed for AAA.
Results A total of 10 patients with JIA were recruited, with a mean age of 12.2 years (range 8.15–18.76 yrs), 50% women. 60% of the patients were concomitantly treated with MTX. Altogether, 70% of the patients demonstrated therapeutic drug levels. Of the 10 patients studied, 3 (30%) had AAA coinciding with the relapse of the disease despite treatment. Also, these 3 patients had undetectable levels of drug. Note that 2 patients (66.6%) who have developed AAA and 4 patients (57.14%) who have not developed AAA also received MTX, there were no significant differences. The duration of JIA was 6.6 years (range 2.54–13.04 yrs) and half time ADL treatment was 2.6 years (range 0.95.5.79 yrs). Half time to ADL treatment before AAA development was 3.62 years (range 1.6–5.44 yrs) and in patients who do not develop AAA was 2.19 years (0.95–5.79 yrs), there were no significant differences.
Conclusions - Significant levels of AAA were present in up to 30% of patients with JIA treated with ADL.
- In our patients, the formation of AAA during treatment with ADL is associated with a loss of clinical response.
- In our preliminary study, the development of AAA was not associated with ADL treatment time.
- In principle, not appear to be significant using combination therapy with MTX and the development of antibodies.
- To consider that this is a preliminary study with a sample size too small, so these results should be confirmed once the study is completed.
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Disclosure of Interest None declared