• Rheumatology Clinical Trials
• Rheumatoid Arthritis

The approved dose of rituximab for the treatment of rheumatoid arthritis (RA) is 1000 mg x 2, but some data have suggested similar clinical efficacy with rituximab 500 mg x 2. The objective of this analysis, presented by Katerina Chatzidionysiou, MD, Karolinska Institute, Stockholm, Sweden, was to compare the efficacy of the 2 doses, given as first or second treatment courses.

The data for this analysis were obtained from the European Collaborative Registries for the Evaluation of Rituximab in Rheumatoid Arthritis (CERERRA), which includes 10 European registries. The registries submitted anonymous datasets with demographic, efficacy, and treatment data on patients who had started rituximab therapy. Treatment and retreatment efficacy were assessed by Disease Activity Score (DAS) 28 reductions and EULAR responses after 6 months.

Information on rituximab doses was available for 2873 (88%) of 3266 patients in the registries. A total of 2625 patients (91.4%) received 1000 mg x 2 of rituximab, and 248 patients (8.6%) received 500 mg x 2. Baseline characteristics that were significantly different between the 500 mg x 2 and 1000 mg x 2 groups, respectively, were: age (55.2 vs 52.6 years; p=0.002), disease duration (13.6 vs 10.9 years; p<0.0001), number of prior biologics (0.7 vs 1.0; p <0.0001), number of prior disease-modifying antirheumatic drugs (DMARDs; 2.6 vs 2.4; p=0.04), baseline DAS28 (5.7 vs 5.9; p=0.02), concurrent DMARDs (72.6% versus 83.1%; p<0.0001), concurrent corticosteroids (65.7% vs 59.3%; p=0.03), and TNF-naïvete (42% vs 62.5%; p<0.0001).

There were no significant differences in DAS28 or Health Assessment Questionnaire (HAQ) responses between the 2 dose groups at 3 months and 6 months. The change in ΔDAS28 at 3 months was 1.3±1.3 in the 500 mg x 2 group versus 1.8±1.4 in the 1000 mg x 2 group (p=0.005, corrected for baseline difference in DAS28). The Δ HAQ at 3 months was 0.3±0.5 in the 500 mg x 2 group versus 0.5±0.6 in the 1000 mg x 2 group (p=0.02). There was no significant difference between the 2 groups in change in DAS28 or HAQ at 6 months. No significant difference was seen in EULAR response or remission rates between the 2 dose groups.

Data on 622 patients who received a second cycle with 2 rituximab infusions were available at 6±1 months. At 6 months after retreatment, the 1000 mg x 2 group versus the 500 mg x 2 group had significant improvements in DAS28 at 12 months (p<0.0001), change in DAS28 at 12 months (p=0.001), and change in DAS28 from 6 to 12 months (p=0.015). EULAR response at 6 months after retreatment was significantly improved in the 1000 mg x 2 versus the 500 mg x 2 group (p<0.0001), but the difference in remission rates was not significant.

In this large, observational cohort, initial treatment with rituximab at 500 mg x 2 and 1000 mg x 2 led to comparable clinical outcomes. The 1000 mg x 2 dose was associated with further DAS28 reductions when given as a second treatment course.

• © 2012 MD Conference Express®