Anti-cyclic citrullinated protein antibodies as a predictor of response to anti-tumor necrosis factor-alpha therapy in patients with rheumatoid arthritis.

Objective: . The treatment of rheumatoid arthritis (RA) has changed dramatically with the introduction of anti-tumor necrosis factor (TNF) agents. Unfortunately, a subset of patients have partial or no response. No measurements were found to predict the efficacy of this therapy. Anti-cyclic citrullinated protein antibodies (anti-CCP) are highly specific and sensitive for RA, and their titer correlates with erosive disease. We investigated the correlation between the efficacy of infliximab therapy and the titer of anti-CCP.

Methods: Thirty consecutive seropositive patients with RA were treated with infusion of 3 mg/kg infliximab on Weeks 0, 2, 6, and 14. Clinical assessment and blood withdrawal were done before each treatment, i.e., at the minimal concentration of the drug. Disease activity was assessed by DAS28 score and by interleukin 6 (IL-6) level. Anti-CCP titer was measured by a commercial ELISA at Week 0 and Week 14.

Results: At baseline, 24 patients were positive for anti-CCP antibodies. In most patients there was a significant correlation between clinical response to therapy and anti-CCP titer. The results were especially noteworthy in those patients who showed a sustained and significant decrease in IL-6 levels through the entire period.

Conclusion: Anti-CCP titer and IL-6 levels might be early predictors of the efficacy of anti-TNF therapy in patients with RA.