Anti-cyclic citrullinated peptide antibodies (anti-CCP) are a serological marker of rheumatoid arthritis (RA), and also have a prognostic value for more aggressive disease. Whether anti-CCP levels may change during treatment according to clinical response is matter of debate. Likewise, it is unknown whether different biological drugs have peculiar effects on anti-CCP levels. This study aimed to investigate changes in anti-CCP serum levels in RA patients on biological drugs with different mechanism of action.
We studied 71 patients with active RA tested positive for anti-CCP who started a first biological drug (54 anti-TNF-α drug, 9 rituximab, 8 tocilizumab). In 14 patients stopping anti-TNF-α treatment for ineffectiveness, rituximab was started. Anti-CCP and rheumatoid factor (RF) isotypes (IgM, IgA, IgG) levels were measured at entry, 12 months and again at 12 months after swapping to rituximab.
After 1 year of therapy of the first biological drug, patients taking anti-TNF-α drugs showed a significant reduction of the anti-CCP levels (p=0.002), and all RF isotypes (p=0.003). Also patients treated with rituximab or tolicizumab had a significant decrease in anti-CCP (p=0.01) and RF isotype levels (p=0.01). Anti-CCP levels did not correlated with DAS28 over time. In patients switching to rituximab after failure of TNF-α blockers, anti-CCP levels did not change at 12 months (p=0.06), despite of the reduction of DAS28 (p=0.02) and RFs levels (p=0.02).
Our study showed that anti-CCP levels may change during RA course, regardless of the biological drug used and the clinical response.