Background/Purpose: The dosage of rituximab (RTX) approved for the treatment of active rheumatoid arthritis (RA) is two intravenous (iv.) 1 g infusions, separated by two weeks. However, it has recently been reported that, after initial treatment with the standard dosage, RTX retreatment at a lower dose may have comparable efficacy and be more cost-effective¹. Our objective was to analyse whether retreatment with RTX at a lower dose (1 g total dose) is equally effective in maintaining the clinical response as the standard dosage of cycles of 2g.

Methods: Observational, descriptive, retrospective study. We analysed the long-term efficacy of RTX retreatment with 1 g (total dose) cycles (2 iv. 500 mg infusions separated by 2 weeks; or 1 g iv single infusion) in routine clinical practise. All patients had initially been treated with at least one 2g (total dose) cycle, with a good response according to clinical judgment. The main efficacy variables were: mean DAS-28 score at the last follow-up visit and at the follow-up visit previous to RTX dose reduction; need to increase the RTX dose to the standard 2g dose; treatment withdrawal due to inefficacy. Secondary variables were: erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) values after retreatment in order to analyse variations between the last follow-up visit (dosage of 1g total dose) and the follow-up visit previous to RTX dose reduction (2g total dose).

Results: From 2006 to 2013, 53 patients (86.8% RA) attended by our Department received at least, one cycle of 2g RTX (standard dosage); 41 out of 53 (77.3%) had a good response. Since September 2011, RTX retreatment was administered at a reduced 1g (total dose)/ cycle in 29 patients (mean age: 59.5±10.4 years; 86.2% female; disease duration 11.7±7.9 years; 79.3% positive for rheumatoid factor/anti-cyclic citrullinated peptides). 79.3% of patients received concomitant disease-modifying antirheumatic drugs (DMARD) and 86.2% glucocorticoids. The mean number of RTX cycles received per patient before RTX dose reduction was 2.03±1.35. No increase in the DAS-28 score was found at the last follow-up visit (2.85±0.98) compared to the follow-up visit previous to RTX dose reduction (3.66±1.17) (p<0.0001). After a follow-up of 20.7±9.3 months, none of the 29 patients required a RTX dose increase or treatment withdrawal due to loss of efficacy. No significant differences were observed in ESR and CRP values between the last follow-up visit and the follow-up visit previous to the RTX dose reduction (mean ESR: 18.1±12.3 vs 18.4±13.1 mm/h, respectively; p=0.50; mean CRP: 0.6±0.8 vs 0.9±1.2 mg/dl, respectively; p=0.07). We observed no increase in the frequency of RTX cycles required after dose reduction (8.5±3.2 (1g total dose) vs 8.2±2.8 (2g total dose) months).

Conclusion: After an initial favourable response to the standard dose of RTX, posterior retreatment with a total dose of 1g/cycle maintained the clinical response over time and was more cost-effective.

Reference: ¹Mariette X et al. Ann Rheum Dis. 2013 May 30

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/analysis-of-the-clinical-sustained-response-after-retreatment-with-a-lower-dose-of-rituximab-in-patients-with-chronic-inflammatory-arthropathies/