#5831 LIGHT CHAIN REMOVAL IN MULTIPLE MYELOMA PATIENTS WITH HFR-SUPRA HEMODIALYSIS: OUR EXPERIENCE
Authors: Heres Salia V Pol , Franco María Jesús Moyano , Garcia Fabiola Alonso , Víbora Elena Jiménez , Lazo Mercedes Salguiera 
Published: June 2023

Abstract

Background and Aims
Kidney injury is a common complication in multiple myeloma (MM) and it has a negative prognostic implication. Most common cause of Acute Kidney Injury (AKI) in these patients is Light chain Cast Nephropathy, where free light chains precipitate in the tubules and bind with uromodulin, turning into intratubular casts that obstruct the tubules and also promote local giant cell reaction and interstitial inflammation and fibrosis. Free light chains (FLCs) can also damage the kidneys due to direct tubular toxicity when excessive amounts are reabsorbed by the proximal tubules. Targeted therapy to reduce FLC load can help recover renal function. Both total reduction and reduction speed are relevant for prognosis. FLC removal through extracorporeal techniques can be used as an adjuvant therapy, having an important part on the evolution of the disease. We gathered data from our experience treating MM patients with AKI with HFR-supra hemodialysis (HD) and analized the evolution and possible influence of this technique on renal recovery.

Method
This is an observational retrospective study. We included all patients with a diagnosis of multiple myeloma and acute kidney injury who received HFR-Supra hemodialysis in between years 2016-2022 in Hospital Virgen Macarena (Seville). We initially performed 6-10 daily HFR-Supra HD sessions and then modulated the frequency based on renal response (if renal replacement therapy had to be continued they underwent a usual hemodialysis regime 3 days a week). We continued these sessions until renal recovery was achieved or free light chain levels were reduced in agreement with the Hematology team. Measurement of pre and post dialysis FLCs was made always at first and last session and at least once in between, depending on the total number of sessions.

Results
12 patients, with mean age at diagnosis 63.6 (43-86) years, presented with AKI stage KDIGO 3. 1 of them was oliguric. Median serum creatinine at diagnosis was 4.4 mg/dL [2,2-17], mean proteinuria was 4,1g/24 h [0,7-8,7] and 66,7% had positive Bence Jones proteinuria (mean 2,3g/24 h). 2 of the patients had previous chronic kidney disease stage 3a. All of them were diagnosed with Light Chain Multiple Myeloma (75% kappa, mean 10346 mg/L; 25% lambda, mean 5990 mg/L). Mean clonal bone marrow plasma cell was 20,7% [2-55]. According to the Revised International Staging System (R-ISS), 25% were stage 2 and 75% were stage 3. Renal biopsy was performed in 4 patients, all showed evidence of Cast Nephropathy. The indication for starting HFR-Supra HD was FLC removal in 9 patients, need of renal replacement therapy in 1 and both in 2 patients. We have experience in our center with using this therapy as an adyuvant treatment and often we start the technique in patients who present with AKI but would not necessarily have immediate need for renal replacement therapy. The goal is to remove FLCs and avoid further damage to the kidney tissue. Out of the 12 patients, 9 were able so stop dialysis (75%). They received a mean number of 12,4 [3-41] sessions in 3,7 [0,2-25] months). Free light chain removal per session was 24% on average [5-43%]. All of them were started on bortezomib-dexamethasone regime as initial chemotherapy for MM. As per renal recovery, at 3 months 33,3% achieved complete response, 11,1% partial response and 55,6% minimal response. At 1 year, 42,9% achieved complete response, 14,3% partial response and 42,9% minimal response. One-year survival rate was 91,7% (1 patient died from respiratory sepsis less than 1 month after diagnosis).

Conclusion
HFR-Supra hemodialyisis achieved a 24% free light chain removal per session on average. After presenting severe AKI (KDIGO 3), almost 43% of patients who received this adyuvant therapy obtained full renal recovery at 1 year and in 75% of patients withdrawal from hemodialysis was possible. 1 year survival was 91,7%.