Practical Issues in ADAMTS13 Testing and Emerging Therapies in Thrombotic Thrombocytopenic Purpura

While our understanding of the pathophysiology of both congenital and acquired forms of thrombotic thrombocytopenic purpura (TTP) has increased, it is only over the past couple of years that this understanding has been translated into clinically significant advances in the diagnosis, management, and treatment of TTP. More specifically, our understanding of the central role of the ADAMTS13 protease in the pathophysiology of TTP has allowed ADAMTS13 testing to have a more prominent role in confirming or re-evaluating the clinical diagnosis of idiopathic TTP with the finding of severely deficient or measurable ADAMTS13, respectively. Additionally, measurement of ADAMTS13 activity at presentation and during remission may be useful to predict both the risk of exacerbation and relapse in patients with idiopathic TTP. There are also several novel approaches to the therapy of TTP including a recombinant ADAMTS13 protease and agents that target the A1 domain of von Willebrand factor (VWF), blocking its interaction with platelet glycoprotein (GP)Ib to prevent the formation of microthrombotic disease in patients with TTP. The addition of these exciting new therapies to conventional plasma-based and/or immune modulating therapies provide hope for improved treatment outcomes for TTP patients.