Maintenance treatment using the purine-synthesis inhibitor mizoribine in a patient with relapsing thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is a rare but life-threatening disease. Although plasma exchange (PE) therapy and corticosteroids are standard remission induction and maintenance therapies, some patients are easily refractory and frequently relapse under treatment with this therapy, and require additional treatment. However, there are limited data about additional treatment interventions. We report a case of 56-year-old man who was hospitalized for fever, general fatigue and hemoglobinuria. Owing to the symptoms and the laboratory findings of hemolysis, he was diagnosed with TTP. He was treated with PE therapy and corticosteroids, and the TTP went into remission. However, his TTP relapsed and remission induction was attempted again. As a remission maintenance treatment, we used combination therapy with the purine-synthesis inhibitor mizoribine (MZR) and corticosteroids. The administration of MZR maintained disease activity with no adverse event for long periods and allowed us to gradually reduce the corticosteroids dose. Hence, we propose that MZR is an effective treatment for TTP maintenance.