Immune thrombotic thrombocytopenic purpura (iTTP) can be treated with rituximab, an anti-CD20 monoclonal antibody, either during acute presentation or disease recurrence. Severe hypersensitivity events, including anaphylaxis and rituximab-induced serum sickness, are undesirable side effects, with a minority of patients not continuing to respond to therapy.

Obinutuzumab and ofatumumab are two different humanized anti-CD20 therapies that have been employed. Around 15 patients got these medications throughout 26 treatment episodes (8 obinutuzumab & 18 ofatumumab), according to an assessment of the UK TTP Registry. Severe infusion-related responses, acute rituximab-induced serum sickness, and short-lived illness remission were all signs that an alternate anti-CD20 therapy was necessary.

After a median of 15 days, all patients had a disease remission (ADAMTS13 [A disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13] activity ≥30 iu/dl), and 92% of episodes ended with complete remission (≥60 iu/dl). With a median relapse-free survival of 17.4 months, 7 patients needed further therapy for illness return. When relapse occurred, all patients continued to react to re-treatment with the previous medication. In 26 treatment sessions, there were 4 adverse events (15%): 2 infections and 2 infusion responses.

Due to their similar safety profiles, lack of major hypersensitivity events, and persistent normalization of ADAMTS13, obinutuzumab, and ofatumumab may be treated as an alternative to rituximab in the treatment of iTTP.

Reference: onlinelibrary.wiley.com/doi/10.1111/bjh.18192