Effectiveness of Haemodiafiltration with Heat Sterilized High-Flux Polyphenylene HF Dialyzer in Reducing Free Light Chains in Patients with Myeloma Cast Nephropathy

Light Chain Cast Nephropathy in Multiple Myeloma: Prevalence, Impact and Management Challenges

“Cast nephropathy” (CN) is a pathological feature of myeloma kidney, also seen to a lesser extent in the context of severe nephrotic syndrome from non-haematological diseases. The name relates to obstruction of distal tubules by “casts” of luminal proteins concentrated by intensive water reabsorption resulting from dehydration or high-dose diuretics. Filtered proteins form complexes with endogenous tubular Tamm-Horsfall glycoprotein. The resulting gel further slows or stops luminal flow upon complete obstruction of distal convoluted tubules and collecting ducts. Thus, a tubular obstructive form of acute kidney injury (AKI) is a common consequence of CN. The pathogenesis of CN will be reviewed in light of recent advances in the understanding of monoclonal disorders of B lymphocytes, leading to the release of immunoglobulin components (free light chains, FLC) into the bloodstream and their filtration across the glomerular basement membrane. Treatment aiming at reduction of the circulating burden of FLC may help recovery of renal function in a fraction of these patients, besides filling the void between the onset of AKI, histopathological diagnosis, and full response to pharmacologic treatment.

Point your SmartPhone at the code above. If you have a QR code reader the video abstract will appear. Or use:

https://youtu.be/-LOd4bqJsIo

Critically ill cancer patient's resuscitation: a Belgian/French societies' consensus conference

To respond to the legitimate questions raised by the application of invasive methods of monitoring and life-support techniques in cancer patients admitted in the ICU, the European Lung Cancer Working Party and the Groupe de Recherche Respiratoire en Réanimation Onco-Hématologique, set up a consensus conference. The methodology involved a systematic literature review, experts' opinion and a final consensus conference about nine predefined questions1. Which triage criteria, in terms of complications and considering the underlying neoplastic disease and possible therapeutic limitations, should be used to guide admission of cancer patient to intensive care units?2. Which ventilatory support [High Flow Oxygenation, Non-invasive Ventilation (NIV), Invasive Mechanical Ventilation (IMV), Extra-Corporeal Membrane Oxygenation (ECMO)] should be used, for which complications and in which environment?3. Which support should be used for extra-renal purification, in which conditions and environment?4. Which haemodynamic support should be used, for which complications, and in which environment?5. Which benefit of cardiopulmonary resuscitation in cancer patients and for which complications?6. Which intensive monitoring in the context of oncologic treatment (surgery, anti-cancer treatment …)?7. What specific considerations should be taken into account in the intensive care unit?8. Based on which criteria, in terms of benefit and complications and taking into account the neoplastic disease, patients hospitalized in an intensive care unit (or equivalent) should receive cellular elements derived from the blood (red blood cells, white blood cells and platelets)?9. Which training is required for critical care doctors in charge of cancer patients?

Acute Kidney Injury in Monoclonal Gammopathies

Monoclonal gammopathies (MG) encompass a variety of disorders related to clonal expansion and/or malignant transformation of B lymphocytes. Deposition of free immunoglobulin (Ig) components (light or heavy chains, LC/HC) within the kidney during MG may result over time in multiple types and degrees of injury, including acute kidney injury (AKI). AKI is generally a consequence of tubular obstruction by luminal aggregates of LC, a pattern known as “cast nephropathy”. Monoclonal Ig LC can also be found as intracellular crystals in glomerular podocytes or proximal tubular cells. Proliferative glomerulonephritis with monoclonal Ig deposits is another, less frequent form of kidney injury with a sizable impact on renal function. Hypercalcemia (in turn related to bone reabsorption triggered by proliferating plasmacytoid B cells) may lead to AKI via functional mechanisms. Pharmacologic treatment of MG may also result in additional renal injury due to local toxicity or the tumor lysis syndrome. The present review focuses on AKI complicating MG, evaluating predictors, risk factors, mechanisms of damage, prognosis, and options for treatment.

Management of acute kidney injury in symptomatic multiple myeloma

Symptomatic multiple myeloma is commonly complicated by acute kidney injury through various mechanisms. The most frequent is the precipitation of monoclonal free light chains with uromodulin in the distal tubules, defining light chain cast nephropathy. Early diagnosis and identification of the cause of acute kidney injury are required for optimizing management and avoiding chronic kidney injury that strongly affects quality of life and patient survival. In light chain cast nephropathy, often manifesting with severe acute kidney injury, renal recovery requires urgent intervention based on vigorous rehydration, correction of precipitating factors, and efficient anti-plasma cell chemotherapy to rapidly reduce the secretion of nephrotoxic free light chains. Currently, the association of the proteasome inhibitor bortezomib with high-dose dexamethasone is the standard regimen in newly diagnosed patients. The addition of another drug such as cyclophosphamide or an immunodulatory agent may improve free light chain response but raises tolerance concerns in frail patients. Further studies are warranted to confirm the role of anti-CD38 monoclonal antibodies, whose efficacy and tolerance have been documented in patients without renal impairment. Despite controversial results from randomized studies, recent data suggest that in patients with light chain cast nephropathy and acute kidney injury requiring dialysis, the combination of chemotherapy with free light chain removal through high-cutoff hemodialysis may increase renal response recovery rates. Kidney biopsy may be helpful in guiding management and assessing renal prognosis that appears to depend on the extent of cast formation and interstitial fibrosis/tubular atrophy. Because of continuous improvement in life expectancy of patients with multiple myeloma, renal transplantation is likely to be increasingly considered in selected candidates.

Intravascular albumin loss is strongly associated with plasma volume withdrawal in dialysis patients

INTRODUCTION

Low circulating albumin closely predicts mortality in end-stage renal disease (ESRD) patients. The cause(s) of hypoalbuminemia (hALB) in ESRD patients remains to be elucidated. The aim of the present study was to determine the role of plasma volume (PV) withdrawal in the reduction of total circulating albumin and essential blood solutes induced by hemodialysis (HD).

METHODS

PV determined with high-precision automated carbon monoxide-rebreathing, total circulating as well as concentration of plasma albumin and electrolytes were assessed prior to and after 4-hour HD in 10 ESRD patients.

FINDINGS

Baseline PV ranged from 3.5 to 6.2 l. After HD, PV was decreased by 689 ± 566 mL (-16%) (P = 0.004). Total circulating albumin was largely reduced after HD (170.8 ± 35.1 vs. 146.1 ± 48.9 g, P = 0.008), while albumin concentration was unaltered. According to a strong linear relationship (r = 0.91, P < 0.001), one-third of total circulating albumin is lost from the intravascular compartment for every liter of PV removed. Similar results were found regarding Na⁺ and Ca²⁺ electrolytes.

DISCUSSION

Total circulating albumin, but not albumin concentration, is substantially reduced by HD in proportion to the amount of PV removed from the circulation. This study highlights the potential contributing role of PV withdrawal to hALB in ESRD patients.

Serum free light chain level at diagnosis in myeloma cast nephropathy-a multicentre study

Myeloma cast nephropathy (MCN) is a common cause of severe renal impairment in multiple myeloma (MM). The level of free light chain (FLC) that causes MCN varies substantially and there is uncertainty about the threshold level that should be used to inform clinical practice. In a multicentre cohort study of 103 patients with a diagnosis of MM and biopsy-confirmed MCN made between 2002–2014, we report prospectively measured levels of serum FLC at diagnosis obtained using a single nephelometric assay (Freelite®) and we explore the relationship between serum FLC level at diagnosis with renal outcome and patient survival. Using a landmark approach, overall survival (OS) was compared between patients who achieved independence from dialysis compared to those who remained dialysis dependent at 3-month, 6-month, 9-month, and 12-month time points. The median serum FLC level at diagnosis was 7531 mg/L (range 107–114600). Serum creatinine was 535 μmol/L (range 168–2993) and eGFR 7 ml/min/1.73 m² (range 1–34). Six patients (5.8%) had an FLC level <1500 mg/L, which is the International Myeloma Working Group threshold for MCN and two patients were below the International Kidney and Monoclonal Gammopathy working group threshold of 500 mg/L; one was hypercalcaemic, and one had high-normal serum calcium level and had received a non-steroidal anti-inflammatory agent. Sixty-nine (67%) patients required haemodialysis treatment of whom 36 (52.1%) recovered independent renal function. Sixty-six (64%) patients died with a median OS of 2.5 years (95% CI 1.8–3.3). A landmark analysis revealed that independence from dialysis was associated with improved survival at 3-months (P = 0.003), 6-months (P = 0.035) and 9-months (P = 0.014); there was no survival benefit observed beyond 12 months (P = 0.146). Serum FLC level at diagnosis was neither associated with renal function recovery nor with OS. This is the largest reported cohort of patients with biopsy-confirmed MCN and prospectively measured serum FLC levels. These results indicate that a serum monoclonal FLC > 500 mg/L should be considered the threshold level associated with the development of MCN.

Albumin handling in different hemodialysis modalities

Hypoalbuminemia is a major risk factor for morbidity and mortality in dialysis patients. With increasing interest in highly permeable membranes and convective therapies to improve removal of middle molecules, transmembrane albumin loss increases accordingly. Currently, the acceptable upper limit of albumin loss for extracorporeal renal replacement therapies is unknown. In theory, any additional albumin loss should be minimized because it may contribute to hypoalbuminemia and adversely affect the patient's prognosis. However, hypoalbuminemia-associated mortality may be a consequence of inflammation and malnutrition, rather than low albumin levels per se. The purpose of this review is to give an overview of albumin handling with different extracorporeal renal replacement strategies. We conclude that the acceptable upper limit of dialysis-related albumin loss remains unknown. Whether enhanced middle molecule removal outweighs the potential adverse effects of increased albumin loss with novel highly permeable membranes and convective therapies is yet to be determined.

High-permeability alternatives to current dialyzers performing both high-flux hemodialysis and postdilution online hemodiafiltration

Most high-flux dialyzers can be used in both hemodialysis (HD) and online hemodiafiltration (OL-HDF). However, some of these dialyzers have higher permeability and should not be prescribed for OL-HDF to avoid high albumin losses. The aim of this study was to compare the safety and efficacy of a currently used dialyzer in HD and OL-HDF with those of several other high permeability dialyzers which should only be used in HD. A prospective, single-center study was carried out in 21 patients. Each patient underwent 5 dialysis sessions with routine dialysis parameters: 2 sessions with Helixone (HD and postdilution OL-HDF) and 1 session each with steam sterilized polyphenylene, polymethylmethacrylate (PMMA), and medium cut-off (MCO) dialyzers in HD treatment. The removal ratios (RR) of urea, creatinine, ß₂ -microglobulin, myoglobin, prolactin, α₁ -microglobulin, α₁ -acid glycoprotein, and albumin were compared intraindividually. A proportional part of the dialysate was collected to quantify the loss of various solutes, including albumin. Urea and creatinine RRs with the Helixone-HDF and MCO dialyzers were higher than with the other 3 dialyzers in HD. The β₂ -microglobulin, myoglobin and prolactin RRs with Helixone-HDF treatment were significantly higher than those obtained with all 4 dialyzers in HD treatment. The β₂ -microglobulin value obtained with the MCO dialyzer was also higher than that obtained with the other 3 dialyzers in HD treatment. The myoglobin RR with MCO was higher than those obtained with Helixone and PMMA in HD treatment. The prolactin RR with Helixone-HD was significantly lower than those obtained in the other 4 study sessions. The α₁ -microglobulin and α₁ - acid glycoprotein RRs with Helixone-HDF were significantly higher than those obtained with Helixone and PMMA in HD treatment. The albumin loss varied from 0.54 g with Helixone-HD to 3.3 g with polyphenylene. The global removal score values ((Urea_RR + β₂ -microglobulin_RR + myoglobin_RR + prolactin_RR + α₁ -microglobulin_RR + α₁ -acid glycoprotein_RR - albumin_RR )/6) were 43.7% with Helixone-HD, 47.7% with PMMA, 54% with polyphenylene, 54.8% with MCO and 59.6% with Helixone-HDF, with significant differences. In conclusion, this study confirms the superiority of OL-HDF over HD with the high-flux dialyzers that allow both treatments. Although new dialyzers with high permeability can only be used in HD, they are in an intermediate position and some are very close to OL-HDF.

[Diagnosis and treatment of kidney involvement in plasma cell diseases : Renal involvement in multiple myeloma and monoclonal gammopathies]

BACKGROUND

Kidney involvement is a common complication in patients with plasma cell diseases.

OBJECTIVE

This article outlines the spectrum of renal involvement in plasma cell dyscrasia and describes diagnostic and therapeutic measures to guide clinical management.

MATERIAL AND METHODS

Evaluation and discussion of the current literature as well as existing guidelines and recommendations of professional societies.

RESULTS

The clinical manifestations of renal involvement in plasma cell disorders are heterogeneous and range from acute cast nephropathy in multiple myeloma to rare forms of glomerulonephritis. The term monoclonal gammopathy of renal significance (MGRS) was introduced to describe kidney involvement caused by monoclonal gammopathy but without evidence for underlying malignancy. Light chain cast nephropathy is the most common renal manifestation in multiple myeloma, whereas monoclonal immunoglobulin deposition disease (MIDD) and renal light chain (AL) amyloidosis can be found in multiple myeloma and MGRS. Decisive is the extended hematological diagnostics in order to exclude the presence of a hematological neoplasm. The treatment of renal involvement in monoclonal gammopathies involves the reduction of the plasma cell clone with cytoreductive treatment. The reduction of the monoclonal protein in serum is prognostically relevant for the renal response to treatment. In the case of histological evidence of a light chain cast nephropathy, high cut-off dialysis is recommended to reduce the free light chains in serum.

CONCLUSION

The spectrum of renal manifestations in plasma cell dyscrasia has been expanded, particularly since the introduction of the term MGRS. Diagnostic and therapeutic management remain an interdisciplinary challenge.

Removal of free light chains in hemodialysis patients without multiple myeloma: a crossover comparison of three different dialyzers

Background

Immunoglobulin light chains are classified as middle molecule uremic toxins able to interact with B lymphocyte membranes leading to the activation of transmembrane signaling. The ensuing impairment of neutrophil function can contribute to the chronic inflammation state of uremic patients, and the increased risk of bacterial infections or vascular calcifications. The aim of this crossover observational study was to assess the difference in free light chain removal by three different hemodialysis filters in patients not affected by multiple myeloma.

Methods

Free light chain removal was compared in the polymethylmethacrylate (PMMA) membrane Filtryzer BK-F, the polyphenylene HFR17 filter and the conventional polysulfone filter F7HPS. Twenty chronic hemodialysis patients were enrolled: mean age was 67.7 ± 17.0 years, M/F = 14/6, dialysis vintage (months) 25.5 ± 32.0. The patients were randomized into two groups of treatment lasting 6 weeks each. The dialysis sessions checked were the midweek sessions and the blood was drawn at times 0, 120’ and 240’. Kappa (k) and lambda (λ) light chain levels, β2microglobulin (β2M), C reactive protein (CRP) and albumin were checked.

Results

K light chain levels were 345.0 ± 100.0 mg/L, λ light chains were 121.4 ± 27.0 mg/L. The values of k light chains at times 120’ and 240’ were significantly lower with PMMA and HFR17 than those obtained with F7. The reduction ratio per session (RRs) for k light chains was 44.1 ± 4.3% with HFR17, 55.3 ± 3.4% with PMMA, 25.7 ± 8.3% with F7 (p = 0.018). The RRs for λ light chains was 30.3 ± 2.9% with HFR17, 37.8 ± 17.3% with PMMA, 14.0 ± 3.9% with F7 (p = 0.032). As to β2M, RRs was 42.4 ± 3.2% with HFR17 vs. 33.9 ± 2.8% with PMMA vs. 6.3 ± 1.9% with F7 (p = 0.022). The three filters tested showed no differences in CRP or albumin levels.

Conclusion

In terms of light chain and β2M removal, the PMMA and on-line HFR filters are similar and both are significantly more effective than the F7 filter in chronic dialysis patients.

Trial registration

The present trial was registered retrospectively (NCT02950389, 31/10/2016).