Investigational drugs in thrombotic thrombocytopenic purpura

Familial and acquired, idiopathic, thrombotic thrombocytopenic purpura (TTP) are life-threatening thrombotic microangiopathies characterized by thrombocytopenia and microangiopathic hemolytic anemia deriving from a deficiency of a disintegrin-like and metalloprotease with thrombospondin repeats (ADAMTS)13 activity induced by genetic defects or autoantibodies. Although the introduction of plasma exchange in 1991 made these conditions curable, many patients still die from TTP and improved therapeutic approaches are, therefore, required.

Based on recent progress in terms of etiology and pathogenesis of TTP, several innovative therapies have been proposed in the last few years. This review provides an overview of results obtained with the ?new? therapeutic options in the light of the ?old? treatments that have been already validated by clinical trials.

Plasma exchange and steroids are still the most effective treatments for TTP, but several new therapeutic approaches promise to further improve the prognosis of affected patients. Immunosuppressants stronger than steroids are expected to inhibit the production of anti-ADAMTS13 autoantibodies in acquired forms when the standard approach fails to reach this goal. Moreover, new antithrombotic drugs are expected to reduce the risk of thrombosis during the period required for inhibiting the production of autoantibodies. Finally, the possibility of replacing the infusion of fresh frozen plasma with recombinant ADAMTS13 could further improve the prognosis of TTP, especially in subjects with familial forms.