Milestones in TTP therapy. The major developments since TTP was first described were the discovery that PEX led to recovery in the majority of patients; the identification of the role of ultra-large VWF multimers, ADAMTS13, and anti- ADAMTS13 antibodies in the pathogenesis of TTP; and the use of rituximab for acute and relapsing TTP. The last decade has seen the development of multiple promising novel targeted therapies.