To study the influence of several factors (rheumatoid factor [RF], anti-cyclic citrullinated peptide [anti-CCP], serum Ig level, and Epstein-Barr virus [EBV] load) on clinical response to rituximab (RTX) after 6 months in rheumatoid arthritis (RA) patients.
Sixty-four patients receiving RTX (two 1-gm doses 2 weeks apart) for active RA were prospectively included. RF, anti-CCP, gamma globulin level, and EBV load were assessed prior to the first RTX cycle. Clinical responses were analyzed 6 months after RTX initiation using the European League Against Rheumatism criteria. Univariate and multivariate analyses were performed to identify factors associated with RTX response at 6 months.
The mean disease duration was 16.4 years and 46 patients (71.9%) had already received at least 1 anti-tumor necrosis factor agent prior to RTX. At 6 months, 46 patients (71.9%) had a good to moderate response to RTX. Anti-CCP positivity was associated with a good to moderate response (odds ratio [OR] 4, 95% confidence interval [95% CI] 1.04-15.5; P = 0.04). RF positivity (P = 0.26) and positive initial EBV load (P = 0.16) were not associated with a good to moderate response. Hyperimmunoglobulin was correlated with a poorer response to RTX than normal Ig levels (OR 0.04, 95% CI 0.005-0.28; P = 0.002).
Anti-CCP positivity was a predictor of good to moderate response to RTX in RA patients. On the other hand, high Ig levels were associated with a poorer outcome in contrast to previous findings. Further support from larger studies is necessary so as to optimize the management of the RA patients with high Ig levels.