Maintenance rituximab for relapsing thrombotic thrombocytopenic purpura: a case report.

BACKGROUND: Appropriate management to prevent relapses of acquired, autoimmune thrombotic thrombocytopenic purpura (TTP) is not clear. Rituximab (375 mg/m2 /week × 4) is effective treatment for acute episodes but it is not consistently effective for prevention of relapses. Maintenance rituximab, 375 mg/m2 /3 months for 2 years, is commonly used to prevent progression of follicular lymphoma, but the outcome of maintenance rituximab to prevent TTP relapses has been rarely reported. CASE REPORT: An 8-year-old girl was diagnosed with acquired TTP in 2008; her ADAMTS13 activity was less than 5%, with a functional inhibitor of greater than 8 Bethesda units/mL. She achieved remission with therapeutic plasma exchange, corticosteroids, and rituximab (375 mg/m2 /week × 4). During the following 6 years she had seven additional episodes. Each episode responded to therapeutic plasma exchange, sometimes requiring additional treatments (corticosteroids, rituximab, and cyclophosphamide). However, these treatments, as well as splenectomy and trials of cyclophosphamide and mycophenolate mofetil during clinical remissions, failed to prevent relapses. Her ADAMTS13 activity remained 8% or less throughout all of her remissions. Maintenance rituximab was begun in 2013: 500 mg (313 mg/m2 ) every 2-3 months × 5, then 600 mg (375 mg/m2 ) every 6 months × 2. After 1 year, her ADAMTS13 was 26%; after 2 years, 51%. During the past 3 years since stopping rituximab, she has remained well, with normal ADAMTS13 activity (70%-78%). CONCLUSION: Maintenance rituximab treatment may be effective for prevention of relapses in patients with acquired, autoimmune TTP, even when splenectomy and intensive immunosuppression, including multiple conventional courses of rituximab, fail to prevent subsequent relapses.