Light chains removal by extracorporeal techniques in acute kidney injury due to multiple myeloma: a position statement of the Onconephrology Work Group of the Italian Society of Nephrology.

Acute kidney injury (AKI) is a frequent complication of multiple myeloma and is associated with increased short-term mortality. Additionally, even a single episode of AKI can eventually lead to end-stage renal disease (ESRD), significantly reducing quality of life and long-term survival. In the setting of multiple myeloma, severe AKI (requiring dialysis) is typically secondary to cast nephropathy (CN). Renal injury in CN is due to intratubular obstruction from precipitation of monoclonal serum free light chains (sFLC) as well as direct tubular toxicity of sFLC via stimulation of nuclear factor (NF)κB inflammatory pathways. Current mainstays of CN treatment are early removal of precipitating factors such as nephrotoxic drugs, acidosis and dehydration, together with rapid reduction of sFLC levels. Introduction of the proteasome inhibitor bortezomib has significantly improved the response rates in multiple myeloma due to its ability to rapidly reduce sFLC levels and has been referred to as "renoprotective" therapy. As an adjunct to chemotherapy, several new extracorporeal techniques have raised interest as a further means to reduce sFLC concentrations in the treatment of CN. Whether addition of extracorporeal therapies to renoprotective therapy can result in better renal recovery is still a matter of debate and there are currently no guidelines in this field. In this positon paper, we offer an overview of the available data and the authors' perspectives on extracorporeal treatments in CN.