The role of rituximab in the management of patients with acquired thrombotic thrombocytopenic purpura

Case presentation A 40-year-old obese black woman developed abdominal pain with progressive generalized weakness over several days. Physical examination was normal except for several small bruises on her extremities. Laboratory data revealed the following: hemoglobin, 5.0 g/dL; platelet count, 4000/mL; creatinine, 0.8 mg/dL; lactate dehydrogenase, 1364 U/L. Peripheral blood smear revealed many schistocytes. Acquired thrombotic thrombocytopenic purpura (TTP) was diagnosed, and treatment was initiated with daily plasma exchange (PEX) and prednisone (1 mg/kg/day). The subsequent report of ADAMTS13 (a disintegrin and metalloprotease with a thrombospondin type 1 motif, member 13) activity <5% with an inhibitor titer of 3 Bethesda Units supported the diagnosis of TTP. After 6 days of PEX, she was asymptomatic, and her platelet count had been normal for 2 days, reaching 178 000/mL; PEX was stopped. Should rituximab have been given as initial treatment of TTP, in addition to PEX and corticosteroids? If her platelet count had decreased to 13 000/mL 3 days after PEX was stopped (an exacerbation, indicating refractory TTP), should rituximab be used in addition to resuming daily PEX? The patient remained well following discontinuation of PEX and corticosteroids. Three years after her first episode, routine measurement of ADAMTS13 activity while she was asymptomatic documented activity of 57%. One year later, while still asymptomatic with normal laboratory evaluation, her ADAMTS13 activity was 4% with an inhibitor titer of 1 Bethesda Unit. Should rituximab be given to prevent a relapse of TTP?