Background/Purpose:

Rituximab is an effective treatment for rheumatoid arthritis (RA). Data on long-term outcomes following rituximab treatment are limited. The aim of this study was to evaluate the long-term efficacy of, and identify predictors of response to, rituximab in our centre.

Methods:

We conducted an observational study of RA patients treated with rituximab from 2003-2016. Demographic and clinical characteristics, including response to treatment, were assessed with tender joint count, swollen joint count, erythrocyte sedimentation rate, and C-reactive protein. Arthroscopy was performed in patients where clinically indicated. Univariate and multivariable logistic regression models were established to evaluate baseline predictors of treatment response. Remission was defined as DAS28-CRP <2.6 or meeting the 2011 ACR/EULAR remission criteria.

Results:

114 RA patients were treated with rituximab. Mean (range) age was 62 (49-75) years. 73% were female, 85% were rheumatoid factor (RF)+, 64% anti-citrullinated protein antibody (ACPA)+, 59% RF+ and ACPA+. Median (IQR) disease duration was 13.5 (7,24.3) years and number of prior conventional synthetic DMARDs (csDMARDs) was 1 (0,2) and biologic DMARDs was 1 (0,2). Baseline characteristics of patients are shown in Table 1. 34 were receiving rituximab monotherapy, 80 were receiving combination therapy with a csDMARD. At last follow-up median (IQR) duration of rituximab treatment was 3.1 (1.8, 6.1) years. 68 (60%) patients maintained remission, 14 (12%) were primary non-responders (7% RF-, 50% ACPA-, 7% RF-ACPA-), 25 (22%) secondary non-responders (24% RF-, 40% ACPA-, 12% RF-ACPA-), and 7 (6%) stopped rituximab due to adverse events (3 hypersensitivity reactions, 2 recurrent LRTIs, 1 neutropenia, 1 severe herpes zoster). Of the 68 patients in remission, 26 (38%) were on rituximab monotherapy and 42 (62%) were receiving combination therapy with a csDMARD. Of the 39 biologic naïve patients, 24 (62%) were in remission and 15 (38%) were not; rituximab achieved equally good outcomes in patients who had previously failed a biologic. No significant baseline predictors of treatment response were identified using logistic regression modelling. In the 44 patients who had an arthroscopy, baseline ESR (p=0.312), CRP (p=0.590), patient global assessment (p=0.934), DAS28-CRP (p=1), TJC (p=0.750), SJC (p=0.848), macroscopic synovitis (p=0.490), macroscopic vascularity (p=0.936), and histologic inflammation (p=0.146) did not predict response to rituximab.

Conclusion:

Rituximab is an effective long-term treatment, with 60% remission, for many of our RA patients, including those who have previously failed a biologic. In this cohort, no baseline demographic, clinical, or serological characteristics accurately predict response to rituximab.

Table 1: Baseline characteristics of 114 rituximab treated patients

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/long-term-outcome-of-rituximab-in-rheumatoid-arthritis-real-world-experience/