Acquired thrombotic thrombocytopenic purpura (TTP) is an autoimmune disorder resulting in potentially life-threating systemic thrombotic microangiopathy due to production of antibodies directed against the von Willebrand factor-cleaving protease ADAMTS13. Typically managed with plasma exchange, glucocorticoids, and the first-generation anti-CD20 monoclonal antibody rituximab, patients with multiple relapses or refractory disease present unique management challenges. We describe a case of a young woman with multiple relapses of TTP despite standard therapy who was treated with ofatumumab, a second-generation anti-CD20 monoclonal antibody, after developing a severe hypersensitivity reaction to rituximab precluding its use. Ofatumumab was effective for the treatment of an acute relapse of TTP in combination with plasmapheresis and as a single-agent for prophylaxis. The patient has had no evidence of relapse 2 years after completion of acute treatment and 1 year after completing prophylactic therapy. Hypersensitivity to ofatumumab did not develop.
Keywords: Drug hypersensitivity; Ofatumumab; Prophylaxis; Rituximab; Thrombotic thrombocytopenic purpura.