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.