Experience with long-term rituximab use in a multiple sclerosis clinic

Abstract

Background: Rituximab is a monoclonal antibody directed at CD20 positive B-lymphocytes and a potential therapeutic option in the treatment of multiple sclerosis. The safety of recurrent dosing is not established. Objectives: The objective of this work was to report the experience of long-term rituximab administration in a comprehensive multiple sclerosis care clinic. Methods: This was a single-center retrospective observational analysis of patients receiving rituximab for the treatment of multiple sclerosis from 2004 to 2015. Different dosing regimens were reviewed to determine whether frequency or dose may affect safety. CD19 and CD20 counts were collected to evaluate B-cell suppression during therapy. Relapses, magnetic resonance imaging activity and rituximab-related adverse events were collected by chart review and prospective database entry. Results: Of 107 patients included, the average duration of treatment was 33.2 months. Seventy-seven patients received recurrent rituximab dosing after initiation. CD19/20 reconstitution occurred in approximately 20% of patients at 6 months, regardless of dosing strategy. Despite CD19/20 counts of 0, three patients had relapses or magnetic resonance imaging activity. Mostly mild side effects in relation to therapy were seen, with the exception of three patients requiring hospitalization for urinary tract infections. Conclusions: In our clinic population, rituximab was well tolerated and safe with recurrent administration.