Changes of anti-citrullinated peptide antibodies titers after biologic treatment in patients with rheumatoid arthritis: a systematic literature review and retrospective study

There is an increasing body of evidence suggesting a direct pathophysiological role of anti-citrullinated peptide antibodies (ACPA) in rheumatoid arthritis (RA), and immunological remission could be a target for treatment. However, data related to the ability of biologics to reduce ACPA titres are contradictory.We aimed to evaluate the changes in ACPA titres after treatment with different biologics in patients with RA. As a first step, a systematic review of the literature available on 3 biologics (TNFi, abatacept and rituximab) and ACPA in patients with RA was performed in Pubmed and Cochrane. As a second step, a retrospective study was performed: all RA patients treated with the 3 above-mentioned biologics were identified. To be included in the analysis, patients had to have at least two titres of ACPA (one before and one after biologic treatment) available. ACPA titres were compared before and after treatment in each of the treatment groups. As a result of the literature review, 24 articles were retained confirming that the data on change in ACPA under biologics is contradictory, particularly for abatacept and TNFi. 144 RA patients (79.3% female, mean age: 56 years) were included in the retrospective analysis: 59 patients had received rituximab, 31 abatacept, 55 TNFi. ACPA titres decreased significantly with rituximab but not with abatacept nor TNFi. Modelling of ACPA titres over follow-up confirmed the significant decrease of ACPA over time rituximab. In this real-life study, ACPA titres only significantly decreased after treatment with rituximab.