FP534
EXTRACORPOREAL TREATMENTS FOR LIGHT CHAIN REMOVAL IN MYELOMA-INDUCED CAST NEPHROPATHY

Introduction and Aims: In patients affected by multiple myeloma (MM), kappa and lambda (K, L) chains may be responsible of acute kidney injury (AKI) due to cast nephropathy (CN). There is a strong rationale supporting the use of extracorporeal treatments aimed to light chain (LC) removal, since AKI recovery is higly related to the reduction of the LC toxic burden. The aim of our work was to evaluate the efficacy of the extracorporeal LC removal, in combination with chemotherapy, on the renal function outcome.

Methods: In collaboration with the Hematologists, we treated 21 patients affected by MM (12 M, 9 F), aged 33-82 yrs. Mean creatinine clearance was 15.5+11 ml/min. On the basis of the AKI-KDIGO classification, 7/21 patients were in stage 2, and the remaining 14/21 on stage 3.

The monoclonal chain was K in 13 patients (8019+5465 mg/L) and L in 8 (7110 +1348 mg/L). Renal biopsy was carried out in 15/21 patients (6 patients excluded due to coagulation problems) and showed: pure CN in 11 patients and a combination of CN and other lesions in 4.

The chemotherapy protocol was the following : induction with Bortezomib, Talidomide and Dexametahsone in association. Melphalan and Prednisone were used in patients not eligible to the bone marrow transplant program.

For the LC removal, different extracorporeal techniques were used, with a personalized approach, based on the LC plasma level and the AKI stage, the metabolic picture, the urinary output: high cutoff membrane (45 KDa) HD, adsorption onto resin, coupled adsorption-filtration with or without dialysis.

Each patient was treated until at least 60% reduction of the plasma LC concentration was reached.

Results: The median number of treatments was 11 per patient. An 85.6% reduction of the plasma LC concentration was obtained. The renal response (based on the International Myeloma Working Group, IMWG, classification) was the following: complete in 19% of the patients, partial in 19%, minor in 25%, unchanged in the remaining patients. Ten patients reached a serum creatinine concentration < 2 mg/dl. Seventeen out of 21 (80%) was dialysis-free in a median time (Bortezomib start-end of extracorporeal treatments) of 32 days. The hematologic response (IMWG criteria) was at least partial in 80% of the cases.

Conclusions: In patients with MM, the use of special extracorporeal treatments able to effectively reduce the LC burden, in combination with the new chemotherapy protocols, may be a valid help for the renal function recovery. Special attention must drawn to the choice of the treatment that should be individualized, and if necessary modified on the basis of the evolving picture.