Synovial Tissue Lymphoid Aggregates Are Associated With Response To Rituximab Therapy In Rheumatoid Arthritis Patients

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Background: To evaluate the clinical and laboratory factors associated with long-term responses to rituximab therapy in patients with RA. Methods: One hundred fourteen RA patients received intravenous Rituximab between 2003-2016. Prior to treatment, arthroscopy and synovial biopsy was performed on a subgroup of this cohort who had active knee arthritis. Demographic, clinical, and outcome data were collected prospectively and immunohistology was performed on synovial tissue biopsies.Results: In the overall cohort, 89% of patients were seropositive for either RF (rheumatoid factor) or ACPA (anti-citrullinated protein antibodies). At baseline, median disease duration was 13.5 years. Seventy-four percent of patients had received a csDMARD and two thirds had received a bDMARD before rituximab. Rituximab monotherapy was used in 34 patients, while 80 patients received rituximab-csDMARD combination therapy. 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. 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 rituximab-induced remission in these patients (p=0.007, OR=7.286 [1.737-30.555]). Conclusion: In this real world series, patients with RA demonstrate long-term, high response rates to rituximab therapy and synovial biopsy B-cell rich lymphoid aggregates are associated with a higher rate of good response.