What is the role of rituximab in the treatment of polymyositis?

Updated: Jan 05, 2021
  • Author: Mythili Seetharaman, MD; Chief Editor: Herbert S Diamond, MD  more...
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The anti-CD20 monoclonal antibody rituximab may be an approach to therapy for refractory cases. The benefit of rituximab was demonstrated in the Rituximab in Myositis (RIM) study, the largest randomized trial ever completed in myositis. RIM included 200 patients with polymyositis, dermatomyositis, or juvenile dermatomyositis not controlled by corticosteroids and other immunosuppressive agents. [39]

The study had a placebo phase design in which half the patients received two rituximab infusions at baseline, whereas the other half received rituximab 8 weeks later. At a median of approximately 20 weeks, 83% of study subjects receiving rituximab met the International Myositis Assessment and Clinical Studies Group preliminary definition of improvement. Whether rituximab was received early or late made no significant difference in the time to achieve the definition of improvement. [39]

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