Successful treatment of myeloma cast nephropathy using bortezomib-based chemotherapy plus selective plasma exchange.

Myeloma cast nephropathy is a major complication of multiple myeloma. Recent evidence has demonstrated that the earlier induction of bortezomib-based chemotherapy with plasma exchange (PE) provides better results for kidney function and patient survival. Due to its non-selectivity, PE with albumin replacement carries the risk of fibrinogen loss, leading to bleeding. We herein report a case of successful treatment of myeloma cast nephropathy using bortezomib-based chemotherapy and selective PE. A 61-year-old woman who had a 20-year history of type II diabetes mellitus was admitted to our hospital for the evaluation of hypercalcemia, severe kidney dysfunction, and anemia. Subsequent bone marrow evaluation and renal biopsy revealed that she had multiple myeloma (IgG-κ) and myeloma cast nephropathy. Ten days after admission, bortezomib-based chemotherapy with selective PE achieved rapid and thorough free light-chain (FLC) reduction; within a month, her kidney function had been recovered (creatinine level, 1.2 mg/dl). Her serum fibrinogen level was not reduced, and no bleeding complication occurred. Five months later, autologous hematopoietic stem-cell transplantation was performed successfully, and the patient's kidney function was stable (creatinine level, 1.1 mg/dl) thereafter. This case report demonstrates the importance of early induction therapy with bortezomib-based chemotherapy and PE in a patient with myeloma cast nephropathy, which is especially applicable in patients aged <65 years. In addition, it shows that selective PE is a safe and effective method of FLC removal.