LAUSR

Background Rituximab is only approved for rheumatoid arthritis (RA) treatment in patients with an incomplete response or intolerance to others DMARDs, including TNF alfa inhibitors. It represents a significant advance in RA biologics arsenal due to its safety and efficacy profiles. Objectives To evaluate the effectiveness of rituximab in RA patients and to compare the response between first-line rituximab patients and those previously exposed to other biologics. Methods An observational retrospective study was conducted, including all the consecutive patients with diagnosis of RA under rituximab, followed at our Rheumatology department until December 2016. Demographic and clinical data were obtained by consulting the national database (Reuma.pt). DAS28 variations and EULAR response were measured at 6, 12 and 18 months. Parametric and non parametric tests were used for statistics (SPSS 20.0). Results We included 63 RA patients (81% of women), with a mean (SD) age of 61 (10) years and a mean disease duration of 19 (10) years; 86% rheumatoid factor positive and 87% anti- citrullinated peptide antibody (ACPA) positive. Bone erosions and extra-articular manifestations were present in 85,7% and 58,7% of the patients, respectively. At baseline, the mean DAS28 was 5.79 (65% and 29% of patients with severe and moderate disease activity, respectively, and 6% in clinical remission). Thirty patients were treated with rituximab as first-line therapy and 33 patients were previously exposed to other biologics. Combination therapy with methotrexate (MTX) was observed in 48% and with others classic DMARDs in 30%, while 22,3% received rituximab monotherapy. First-line rituximab option was justified by lung involvement in 21%, past malignancy in 13%, recurrent infections in 5%, congestive cardiac failure in 3%, vascular involvement in 3% and untreated latent tuberculosis in 3%. In the group previously exposed to biologics, 13% switched therapy due to ineffectiveness and 87% due to adverse events. No significant differences were found between the 2 groups in terms of age, gender, concomitant use of MTX and baseline DAS28. The group previously exposed to biologics had a longer disease duration (mean 23 vs 15 years, p=0.001) and fewer patients with ACPA seropositivity (79% vs 97%, p=0.035). There was a significant reduction of DAS28 at 6, 12 and 18 months (p<0.001 for all). Fifty six percent of the patients achieved a EULAR response at 6 months, 46% at 12 months and 59% at 18 months. DAS28 variation at 6 months differed significantly between groups, with a better clinical response in naive biological patients comparing to those previously exposed to biologics (median 1.173 vs 0.477; p=0.038). There were no differences in terms of DAS28 variation at 12 and 18 months (p=0.642 and p=0.135, respectively) and in EULAR responses at 6, 12 and 18 months between the groups (p=0.289, p=0.523 and p=1.000, respectively). Conclusions Our study confirms the effectiveness of rituximab in RA patients and suggests a higher magnitude of response in naive biological patients at 6 months of RTX therapy. These findings put in perspective an extension of rituximab as a first-line biologic for RA treatment. Disclosure of Interest None declared