[Treatment strategy for patients with thrombotic thrombocytopenic purpura]

Thrombotic thrombocytopenic purpura (TTP) is a rare and potentially life-threatening disease that is characterized by microangiopathic hemolytic anemia, consumptive thrombocytopenia, and ischemic organ damage resulting from the formation of platelet-rich thrombi in the microvasculature. It is especially related to a severe deficiency of ADAMTS13, the specific von Willebrand factor-cleaving protease. Thus, <10% of the normal activity of ADAMTS13 is an essential diagnostic marker for establishing a diagnosis of TTP. TTP can be of congenital form that is termed the Upshaw-Schulman syndrome (USS) that is caused by genetic abnormality of ADAMTS13 and acquired form that is caused by autoantibodies against ADAMTS13. The congenital form is treated with the infusion of fresh frozen plasma, and the treatment of the acquired form involves plasma exchange combined with immunosuppressive therapy that uses corticosteroids and rituximab. Recently, the efficacy and safety of new drugs caplacizumab, single-domain antibody against ADAMTS13, and recombinant ADAMTS13 products have been reported in large-scale clinical trials conducted in other countries. These results suggested the better outcome in the treatment for the patients with TTP in the near future.