#5130 THE EXPERIENCE OF SELECTIVE PLASMA EXCHANGE THERAPY IN PATIENTS WITH MULTIPLE MYELOMA
Authors: Fomin Aleksandr , Fedulkina Veronika , Grankin Victor , Zulkarnaev Aleksei 
Published: June 2023

Abstract

Background and Aims
High concentrations of free light chains (FLCs) in multiple myeloma lead to cast-nephropathy and obstructive acute renal failure in 18-56% of patients. The aim of this research is to estimate the efficiency of extracorporeal free light chains of immunoglobulin elimination under this pathological condition during plasma exchange therapy using selective filters.

Method
Selective plasma exchange therapy (SEPET) was carried out in 11 patients with multiple myeloma. The patients were 61 [47-69] years old. Paraproteinemia level at primary examination varied from 1.6 to 78.8 g/liter. All patients exhibited proteinuria of 0.56 to 12.7 g/day, Bence Jones protein excretion (from 0.4 to 11.2 g/day) was detected in 9 cases. Blood creatinine levels ranged from 272 μmol/L to 534 μmol/L. None of the patients required renal replacement therapy. FLCs levels above 500 mg/L, irrespective of azotemia level, served as an indication for starting the procedure. All patients received VMP induction chemotherapy after sessions of selective plasma exchange therapy. SEPET was carried out on a “Multifiltrate” (Fresenius) hemodialysis machine in hemofiltration mode. «Evaclio 2C20» plasmafilter (Japan) was used. Patients underwent one procedures of SEPET in a dose of 3 volumes of circulating plasma. Blood flow velocity during varied from 40 to 60 ml/min, the duration of each procedure was 5-6 hours. Plasma substitution was performed with «Prismasol K4» solution - 10.0 L and albumin solution 20%-400 ml. Regulated clotting by nonfractionated heparin was calculated individually from the APTT values. No early or delayed complications of extracorporeal hemocorrection were recorded. FLCs, creatinine levels, and coagulogram results of patients were examined before and after the procedure.

Results
Analysis of serum FLC values before treatment showed a significant increase of κ- or λ-FLC levels, significantly surpassing normal values: 3-21.5 mg/liter κ-FLC and 5-27 mg/liter λ-FLC, with κ/λ-FLC proportion of 0.25-1.65. The primary levels of involved FLC medians in the group were 472 [312;44700] mg/L for κ-FLC and 163 [ 473; 24673] mg/L for λ-FLC, κ/λ-FLC proportions were 2.89. Through the membrane of the plasma filter “Evaclio 2C20” are sieved and removed substances with a molecular weight less than the molecular weight of albumin (65 kD). Kappa FLCs circulate as monomers of 22 kDa but may assemble into dimers of 45 kDa, particularly lambda FLCs. There is a partial loss of albumin. High molecular weight substances do not pass through this membrane. During SEPET the κ-FLC level in the plasmafiltrate was 272 mg/L, the λ-FLC level was 94 mg/L. After SEPET median serum κ-FLC was 231 mg/L, median serum λ-FLC was 96 mg/L. Compared with baseline data, serum FLC levels decreased after 24 hours, so that median serum κ-FLC was 281 mg/L, median serum λ-FLC was 101 mg/L. Clinical tolerance of extracorporeal detoxification was satisfactory and hemodynamically stable in all patients; and there were no were traumas of blood elements or decrease of serum albumin. Renal function recovered in 3 patients in the course of therapy, improved in 5 patients with renal insufficiency, and remained unchanged in 3 patients.

Conclusion
The Selective plasma exchange therapy directly removes FLCs excess from circulating blood. Rapid reduction of FLCs level in the course of selective extracorporeal elimination can prevent the development of irreversible renal failure and make it possible to carry out adequate antitumor therapy.