Low-dose rituximab as effective as high-dose, but safer

Results of a Spanish two-centre study suggest that low doses of rituximab are equally as effective as high doses, but have a superior safety profile [1]. A standardised treatment schedule for this anti-CD20 monoclonal antibody has yet to be established. The study authors think these results will change clinical practice.

The efficacy and safety of 2 rituximab regimens were compared at 2 large MS centres in Barcelona and Girona. The Barcelona centre (BC; n=249) applied higher doses of rituximab than the Girona centre (GC; n=54). In the BC, at least 3 cycles of 2 g intravenously (IV) were followed by 1 g every 6 months; in the GC, a minimum of 1 cycle of 2 g IV was followed by 500 mg every 6 months. For the 303 study participants, clinical progression plus inflammatory activity was the main reason to start rituximab in the BC (45.8%) as well as the GC (79.6%).

At baseline, mean annualised relapse rate (ARR) was 0.37 (BC) and 0.33 (GC), median EDSS was 5.5 and 6.0, and the proportion of MRI with contrast-enhancing lesions was 32.4% and 42.6%, respectively. In the BC and GC, mean ARR decreased to 0.05 (87.5%, P<0.001) and 0.03 (90.3%, P=0.018), respectively, in the first year of treatment. In the third year, ARR was 0.08 (88.3%, P=0.016) and 0.0 (100%, P=0.172). Of participants with progressive MS, EDSS remained stable or improved in 79.4% (BC) and 71.4% (GC). The proportion of patients with contrast-enhancing lesions and new T2 lesions were 2.7% and 19% (BC) and 8% and 16% (GC) after 1 year; this decreased 0% and 12% (BC) and 0% and 0% (GC) after 3 years.

In the first year, the incidence of adverse events was 14.8% in the BC and 4.1% in the GC cohort. There were no differences in the dynamics of CD19 lymphocyte percentages. Throughout the first 3 years, IgG values decreased significantly in the BC but not in the GC cohort.

1. Midaglia L, et al. Rituximab treatment for MS: an observational multicentric dose comparison. MSVirtual 2020, PS01.05.