Background/Purpose: : The standard dose of rituximab (RTX) in rheumatoid arthritis (RA) is two intravenous (iv) 1 g infusions, separated by two weeks. Recently, the efficacy of a low-dose of RTX for retreatment in RA patients has been reported (1). Our aim is to assess the long-term sustained effectiveness of a low-dose of RTX in daily clinical practice.

Methods: Observational retrospective study in a tertiary hospital. We included all RA patients that have received at least one cycle of RTX, at a standard dose, between May 2006 and May 2017. We selected those patients who achieved a good or moderate EULAR response, and thereafter were down-titrated to a low-dose regimen (1 g), according to clinical judgment. Variables analyzed: age, sex, duration of RA, presence of ACPA (antiCCP2) and rheumatoid factor (RF), use and dosage of glucocorticoids (GC) and synthetic DMARD (csDMARD) before and after RTX treatment, number of biologic DMARD (bDMARD) used prior to initiate RTX. Disease activity was measured using the DAS28-ESR index (at baseline, at initiation and during the low-dose RTX period, and at the last follow-up visit).

Results: From 2006 until 2017, 53 RA patients received, at least, one cycle of 2g RTX. Thirty-seven patients (69.8%) achieved a good or moderate EULAR response (mean initial pre-RTX DAS-28: 5.79 ± 1.17) and were step-down to a low dose re-treatment regimen. Baseline characteristics of patients receiving low-dose RTX: mean age 56.4 ± 10.9 years; 13.5% male, mean disease duration 12.7 ± 9.8 years, 91.9% RF + and 97.3 % ACPA +; mean pre-low dose RTX DAS-28: 4.08 ± 1.39. Thirty-four patients (91.9%) were on cs-DMARDs (51.4% with methotrexate (MTX) and 37.8% with leflunomide (LEF)), and 32 (86.5%) received concomitant GC. RTX was the first biologic only in 10 patients (27%). In the remaining cases, the mean number of previous b-DMARDs was 2.52 ± 1.5. Twenty-seven patients (73%) received only one standard cycle (2g) before RTX dose reduction.

A statistically significant reduction in the mean DAS-28 was observed between the first visit on 1g RTX (4.08 ± 1.39) with the last follow-up visit (3.04 ± 0.95; p< 0.0001), as well as, with the mean DAS-28 during the low-dose RTX period (3.63 ± 0.92; p<0.006).

11 were able to reduce dosage (8 MTX, 3 LEF), with a significant reduction for MTX (16.5 ± 4.4 mg vs. 11.92 ± 8.0 mg; p<0.01). From the 32 patients initially receiving GC, 18 (56.3%) were able to reduce dose (9.36 ± 5.06 vs 4.80 ± 4.04; p< 0.0001), and 9 (28%) discontinued GC therapy.

After a follow-up of 3 ± 1.8 years, only 10 (25%) patients have withdrawn RTX. Reasons were: recurrent infections in 4 cases (11%), loss of efficacy in 2 cases (5.6%), and adverse event and patient preferences in one case, respectively.

Conclusion: A sustained clinical response was observed with the 1 gr retreatment of RTX over a long term period.

Reference:

1. Mariette X et al. Ann Rheum Dis 2014; 73: 1508-14.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/sustained-clinical-response-in-refractory-rheumatoid-arthritis-patients-with-a-low-dose-rituximab-retreatment-regimen-a-single-center-experience/