Long-term risk of relapse in immune-mediated thrombotic thrombocytopenic purpura and the role of anti-CD20 therapy

•Forty percent of patients with iTTP relapse after 5 years of follow-up.•Preemptive anti-CD20 therapy is efficacious in 96% of ADAMTS13 relapses regardless of relapse frequency to achieve ADAMTS13 levels of >20%. [Display omitted] Disease relapse is recognized as a risk in immune-mediated thrombotic thrombocytopenic purpura (iTTP) after treatment of the acute presenting episode. Identification of patients at risk of relapse and its patterns are yet to be clearly established. We reviewed patients with iTTP having had >3 years of follow-up over 10 years in the United Kingdom to identify patient characteristics for relapse, assess relapse rates and patterns, and response to anti-CD20 therapy in those with a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) relapses (ADAMTS13 activity of 20%. Anti-CD20 therapy was demonstrated to be an effective long-term treatment regardless of relapse pattern and there was no loss of this treatment response after subsequent treatment episodes. The acute mortality of immune-mediated thrombotic thrombocytopenic purpura (iTTP) has been markedly reduced with the use of plasma exchange, immune suppression, and caplacizumab, and it is now often a chronic disease with relapsing episodes of thrombotic microangiopathy. In this month’s CME article, Doyle et al show from UK national registry data that 40% of patients with iTTP relapse after 5-years’ follow-up and that preemptive anti-CD20 therapy is highly effective in preventing clinical rela