Rituximab (RTX) is an anti-CD20 monoclonal antibody, widely used as an off-label treatment for multiple sclerosis (MS). Despite well-known efficacy and safety, RTX regimen has not yet been standardized.
We aimed to compare efficacy and safety data of two different rituximab doses at two large Catalan multiple sclerosis centres.
A two-centre ambispective study considering all MS patients that have received at least one RTX cycle until February 2020 was conducted. In Barcelona centre (BC), RTX regimen used was 2g intravenously (IV), at least during 3 cycles, followed by 1g every 6 months, while in Girona centre (GC), was 2g IV, at least the first cycle, followed by 500mg every 6 months. Patients were clinically followed every 6 months with lab tests, and brain MRI scans were performed at baseline and yearly thereafter. Baseline clinical, radiological and demographic characteristics were collected. Annual relapse rate (ARR), contrast-enhancing lesions (CELs) and new T2 lesions at one and third year on treatment, as well as EDSS changes at last follow-up visit, were evaluated. Also, the dynamics of CD19% lymphocytes and IG immunoglobulin (IgG) values in serum, as well as the incidence of adverse events (AE) were described.
A total of 303 patients (249 at BC and 54 at GC) were included. Main reason to start RTX was clinical progression plus inflammatory activity (clinical, radiological or both) (45.8% BC vs 79.6% GC). No differences on age at RTX onset, gender and disease duration were found between both centres. At baseline, mean ARR was 0.37±0.6 (BC) vs. 0.33±0.5 (GC); median EDSS was 5.5 (1-9.0) (BC) vs. 6.0 (1-8.0) (GC); and proportion of MRI with CELs was 32.4% (BC) vs. 42.6% (GC). ARR decrease to 0.05 (87.5%, p<0.001) for BC vs. 0.03 (90.3%, p=0.018) for GC at first year, and to 0.08 (88.3%, p=0.016) vs. 0 (100%, p=0.172) at third year. Considering only progressive MS phenotypes, 79.4% vs. 71.4% of patients remained stable or improved the EDSS. Regarding MRI findings, percentages of patients with CELs and new T2 lesions (BC vs GC) were 2.7% vs. 8% and 19% vs. 16% at one year; and 0% vs. 0% and 12% vs. 0% at third year. AE incidence was higher at BC during the first year (14.8% vs 4.1%). No difference in the dynamics of CD19% lymphocytes was found, while IgG values decreased significantly in the BC cohort throughout the first 3 years.
In the treatment of multiple sclerosis, low doses of rituximab seem to offer similar effectiveness with better safety profile than high doses.