Rituximab-refractory thrombotic thrombocytopenic purpura responsive to intravenous but not subcutaneous bortezomib

BACKGROUND Thrombotic thrombocytopenic purpura (TTP) is often characterized by formation of antibodies against a disintegrin and metalloprotease with thrombospondin repeat, member 13 (ADAMTS13). Therapeutic plasma exchange (PEX) is the basis of TTP therapy, with additional immunosuppression to eradicate ADAMTS13 antibody-producing B cells. CASE REPORT We describe a case of a 22-year-old female with TTP refractory to PEX, high-dose corticosteroid therapy, and rituximab. Laboratory blood tests showed a severe ADAMTS13 deficiency and the presence of an inhibitor. Although one cycle of subcutaneous bortezomib resulted in clinical improvement, the patient remained PEX dependent. A second course of intravenous (IV) bortezomib resulted in a complete remission without evidence of relapse after 18 months. CONCLUSION This case confirms the efficacy of bortezomib for refractory TTP and suggests that the in vivo activity of IV bortezomib may be distinct from subcutaneous drug in this setting.