Humanized anti CD-20 as an alternative in chronic management of relapsing thrombotic thrombocytopenic microangiopathy resistant to rituximab due to anti chimeric antibody

Acquired Immune thrombotic thrombocytopenic purpura (iTTP) is considered among clinical situations that needs not only urgent treatment in acute setting but also long term management to prevent relapses. Important progresses have been made in management of these patients that are definitely associated with reduced mortality and relapse rate. However, there are still noticeable percentage of patients that may relapse despite application of modern treatment strategies including preemptive rituximab infusions. Hereby, we share our experience concerning a frequently relapsing iTTP due to development of anti-rituximab antibody. In our case administration of obinutuzumab, a humanized type II anti CD-20 antibody was associated with complete peripheral blood B cell depletion and increasing plasma ADAMTS-13 activity.