Background/Purpose: Activated B lymphocytes and plasma cells are implicated in the pathogenesis of rheumatoid arthritis (RA). The anti-CD20 monoclonal antibody therapy (Rituximab) is an effective therapy in some RA patients. The goal of this study was to evaluate the clinical and laboratory factors associated with long-term responses to Rituximab therapy in patients with RA.

Methods: One hundred and fourteen RA patients received Rituximab (1g doses x 2, 2 weeks apart), at a single centre, between 2003-2016. Prior to treatment, arthroscopy and synovial biopsy was performed on patients in this cohort who had active knee arthritis. Demographic, clinical and outcome data were collected prospectively and immunohistology was subsequently performed on synovial tissue biopsies. Clinical and laboratory outcomes were evaluated using linear and binary logistic regression.

Results: The median (IQR) disease duration was 13.5 (7, 24.3) years. The number of prior csDMARDs was 1 (0, 2), and biologic DMARD was 1 (0, 2). Rituximab monotherapy was used in 34 patients, while 80 patients received rituximab-csDMARD combination therapy. Forty-four patients underwent an arthroscopy and synovial biopsy prior to treatment. Synovial tissue lymphoid aggregates (LA) were observed in 21 subjects, of which 17 (81%) showed complete or partial remission in response to treatment with Rituximab. The presence of LA was significantly associated with remission in these patients treated with rituximab (p=0.007, OR=7.286 [1.737-30.555]). A significant association was also shown between LA and CD138 plasma cell staining in the synovial biopsies (p< 1.0x10^-4, OR=22.667 [3.979-129.119]). 73% of patients were female, 85% were rheumatoid factor (RF) positive, 64% anti-citrullinated protein antibody (ACPA) positive, 59% double positive, and 11% seronegative. Rituximab treatment follow-up time had a median (IQR) of 3.1 (1.8, 6.1) years and median number of treatment courses was 3 (2, 5). Sixty-eight patients (60%) reached sustained remission, while 14 (12%) were primary non-responders, 25 (22%) were secondary non-responders, and 7 (6%) stopped due to adverse events. Twenty-six of the 68 patients in remission (38%) received Rituximab monotherapy and 42/68 (62%) received combination therapy with a csDMARD. Twenty-four of 39 (62%) biologic naïve patients achieved remission on treatment with rituximab. There was no significant association between any other clinical or laboratory markers and remission in patients treated with rituximab.

Conclusion: These data show significant evidence for lymphoid aggregates as a predictive marker for response to treatment with rituximab. Rituximab is an effective long-term treatment for RA, with high remission rates that are associated with synovial lymphoid aggregates.

« Back to ACR Convergence 2021

ACR Meeting Abstracts - https://acrabstracts.org/abstract/synovial-tissue-lymphoid-aggregates-are-associated-with-response-to-rituximab-therapy-in-rheumatoid-arthritis-patients/