Prognostic value of kidney biopsy in myeloma cast nephropathy: a retrospective study of 70 patients

Renal outcome in multiple myeloma patients with cast nephropathy: a retrospective analysis of potential predictive values on clinical and renal outcome

OBJECTIVE

Cast nephropathy (CN) is the leading cause of acute kidney injury (AKI) in multiple myeloma (MM). Since it is sparsely documented why some patients with CN do achieve a renal response while others do not, we describe a single-center cohort of patients with multiple myeloma and biopsy-confirmed CN to evaluate potential markers of renal response.

METHODS

The data was collected as a retrospective, single-center analysis of CN-patients treated at the Medical University Vienna between 01/01/2004 and 01/01/2022. Baseline parameters and clinical outcome was compared between renal responders and non-responders.

RESULTS

Among 28 patients with CN, n = 23 were assessed for renal response (14 responders; 9 non-responders). Renal responders were younger (median age: 61 years; 77 years, p = 0.039), showed higher overall survival (153months; 58months, p = 0.044) and achieved hematologic response (≥PR) to first-line therapy (p = 0.029), and complete hematologic response (CR) at any time (p = 0.025) significantly more often. Further, we could show that rapid initiation of anti-myeloma therapy after initial presentation correlated significantly with renal response (median 9 days; 27 days, p = 0.016). Analyses of kidney biopsy specimens revealed that patients with a high IF/TA score showed end stage renal disease (dialysis ≥ 3 months) significantly more often (p = <0.001).

DISCUSSION

In summary, our data suggests, that a rapid start with systemic hematologic treatment in patients with MM and CN is crucial and achieving an early hematologic response is important for renal recovery. Moreover, achieving a deep hematologic response and subsequent renal recovery improves clinical outcome as reflected by an overall survival benefit.

A rare case of IgA lambda multiple myeloma in a 32-year-old woman with t(14;16) translocation associated with kidney injury and non-albumin proteinuria

BACKGROUND

Multiple myeloma (MM) is a malignant disorder characterized by monoclonal differentiated plasma cells. While it is more commonly diagnosed in elderly individuals, it can also affect younger populations, though with a lower incidence.

CASE PRESENTATION

Here, we present the case of a 32-year-old woman diagnosed with IgA lambda MM. She presented with fatigue, nausea, acute kidney injury (AKI) with a rapid increase in creatinine, and anemia. A kidney biopsy was done to rule out a rapidly progressive glomerular disease and a diagnosis was thus reached. A genetic workup revealed t(14;16) translocation and an extra copy of TP53. The patient received aggressive intravenous steroids and intravenous fluid resuscitation, resulting in an improvement in renal function. Treatment with daratumumab in combination with bortezomib, thalidomide, and dexamethasone was initiated and well tolerated. Despite the generally poor prognosis of IgA MM, our case emphasizes the importance of considering MM in young patients with unexplained kidney injury.

CONCLUSION

Early recognition and prompt intervention are essential in managing MM patients, especially in those with high-risk cytogenetic abnormalities. This case serves as a reminder for clinicians to maintain a high index of suspicion for MM, even in younger populations, when presented with unexplained kidney injury.

Kidney outcomes and prognostic factors of myeloma associated acute kidney injury in the contemporary era

Myeloma cast nephropathy (MCN) has historically been associated with poor kidney outcomes. We aimed to evaluate the kidney outcomes and identify prognostic factors of myeloma-associated acute kidney injury (M-AKI) in the contemporary era of anti-plasma cell therapy. Patients who received anti-myeloma therapy with M-AKI (January 2012 to June 2020) from a single centre were identified from electronic medical records. Diagnosis of MCN was either biopsy confirmed (BC) or clinically suspected (CS), the latter defined as acute kidney injury with reduced estimated glomerular filtration rate (eGFR) <30 mL/min/1.73 m2 and involved serum free light chains (iSFLC) >500 mg/L at diagnosis. Twenty-six patients with M-AKI were identified (BC: n = 13, CS: n = 13). Median eGFR at diagnosis was 12 (interquartile range 6-20) mL/min/1.73 m2 . All six dialysis-requiring patients achieved dialysis independence after 71 (43-208) days. The best-achieved eGFR was 47 (32-67) mL/min/1.73 m2 after 120 (63-167) days post-treatment, which was maintained at 47 (33-66) mL/min/1.73 m2 12 months post-treatment. Patients with best-achieved eGFR above the median were more likely to have achieved an iSFLC of <20 mg/L (above median group 62% versus below median group 0%; p < .001) and lower best post-treatment iSFLC (20 (12-90) versus 67 (29-146) mg/L; p < .05). Best-achieved iSFLC was a prognostic factor for superior eGFR following treatment for M-AKI. Despite low eGFR at diagnosis, contemporary anti-myeloma therapy can achieve significant recovery of kidney function.

Exosomal miR-21-5p derived from multiple myeloma cells promote renal epithelial-mesenchymal transition through targeting TGF-β/SMAD7 signalling pathway

The prognosis of multiple myeloma (MM) patients combined with renal insufficiency is poor. Renal fibrosis is an important pathological cause for MM patients combined with renal insufficiency. It is reported that epithelial-mesenchymal transition (EMT) of renal proximal tubular epithelial cells is an important mechanism in renal fibrosis. We speculated that EMT might play an important role in the renal insufficiency of MM with unclear mechanism. MM cells derived exosomes could affect the function of targeted cells by delivering microRNAs (miRNAs). Literature has shown that the expression of miR-21 is closely related to EMT. In this research, we found that co-culture of HK-2 cells (human renal proximal tubular epithelial cells) and exosomes derived from MM cells promoted the EMT of HK-2 cells, resulting in the down-regulation of epithelial-related marker (E-cadherin), and up-regulation of stroma-related marker (Vimentin). Meanwhile, the expression of SMAD7, one of the downstream targets in the TGF-β signalling pathway, was suppressed and the expression of TGF-β was increased. After transfecting the inhibitor of miR-21 in MM cells, the expression of miR-21 in exosomes secreted by MM cells was significantly decreased, and the co-culture of these treated exosomes and HK-2 cells inhibited the EMT of HK-2 cells. In conclusion, these findings showed that exosomal miR-21 derived from MM cells could promote renal EMT through targeting TGF-β/SMAD7 signalling pathway.

Risk nomogram for assessing renal recovery in patients with newly diagnosed multiple myeloma-related renal impairment

To determine risk factors affecting renal recovery in newly diagnosed multiple myeloma (NDMM) patients with renal impairment (RI) and establish a risk nomogram. This multi-center, retrospective cohort study included 187 NDMM patients with RI, 127 of whom were admitted to Huashan Hospital and assigned to the training cohort and 60 were admitted to Changzheng Hospital and assigned to the external validation cohort. The baseline data of the 2 cohorts were compared, and survival and renal recovery rates were analyzed. Independent risk factors affecting renal recovery were determined by binary logistic regression analysis, and a risk nomogram was established and subsequently tested in the external validation cohort. Results: The median overall survival (OS) improved in patients who achieved renal recovery etc within 6 courses of MM directed treatment compared with patients without renal recovery. Median time to renal recovery was 2.65 courses, and the cumulative renal recovery rate during the first 3 courses was 75.05%. Involved serum free light chain (sFLC) ratio of >120 at diagnosis, time from renal impairment to treatment > 60 days, and a hematologic response without a very good partial remission (VGPR) or better resulted as independent risk factors for renal recovery during the first 3 courses. The established risk nomogram had good discriminative ability and accuracy. Involved sFLC was a key factor affecting renal recovery. Starting treatment as soon as possible after detecting RI and achieving deep hematologic remission during the first 3 courses of treatment helped achieve renal recovery and improve prognosis.

Role of light chain clearance in the recovery of renal function in multiple myeloma: another point of view

BACKGROUND

Acute kidney injury (AKI) in patients with multiple myeloma (MM) requiring renal replacement treatment (RRT) is associated with high morbidity and mortality. Early reduction of serum free light chains (FLC) using both targeted therapy against MM and intensive hemodialysis (IHD) may improve renal outcomes. We evaluated the effectiveness of two different RRT techniques on renal recovery in an MM patient population: standard dialysis procedure vs IHD with either polymethylmethacrylate (PMMA) or hemodiafiltration with endogenous reinfusion (HFR).

METHODS

This was a multicentric retrospective study with severe AKI related to MM, between 2011 and 2018. Twenty-five consecutive patients with AKI secondary to MM requiring RRT were included. Patients that underwent IHD received six dialysis sessions per week during the first 14 days (PMMA vs HFR). All patients were diagnosed with de novo MM or first relapsed MM. Primary outcome was renal recovery defined as dialysis-free at 6 months follow-up.

RESULTS

A total of 25 patients were included. Seventeen patients received IHD and eight standard dialysis. All patients were treated with targeted therapy, 84% bortezomib-based. Of the 25 patients included, 14 (56%) became dialysis independent. We observed a higher proportion of patients who received IHD in the group who recovered kidney function compared with those who remained in HD (92.9% vs 36.4%, P = .007). In our study, the use of IHD to remove FLC had a statistically significant association with renal recovery compared with the standard dialysis group (P = .024).

CONCLUSION

Early reduction of FLC with IHD as an adjuvant treatment along with MM-targeted therapy may exert a positive impact on renal recovery.

[Renal failure in multiple myeloma: Specific management issues]

Renal impairment is common during multiple myeloma and persistent reduction in kidney function strongly affects prognosis. Cast nephropathy, by monoclonal free light chains precipitation with uromodulin in renal tubules, is the main cause of acute kidney injury in multiple myeloma. Kidney biopsy, although not necessary for diagnosis, allows assessment of renal prognosis according to the extent of cast formation, tubular atrophy and interstitial fibrosis. Prevention and early diagnosis of acute kidney injury are essential to optimize management and avoid progression to chronic kidney disease. Rehydration, interruption of nephrotoxic treatments, correction of precipitating factors, anti-plasma cell chemotherapy can rapidly reduce the free light chains nephrotoxicity. The association of the proteasome inhibitor Bortezomib and high dose Dexamethasone is the reference treatment in newly diagnosed patients with renal impairment. Adding Cyclophosphamide or the immunomodulator Lenalidomide may improve the hematological response, but with a poorer tolerance. Use of anti-CD38 monoclonal antibodies is being evaluated in this population. Hemodialysis with high-flux or high-cut-off membranes, combined to chemotherapy, may improve renal function recovery. Management of multiple myeloma have to be adapted in patients with chronic kidney disease, dialysis or kidney transplantation. Because of improvement in global survival, kidney transplantation remains an option to consider in selected patients. Collaboration between hematologists and nephrologists is essential throughout the course of the disease.

Successful renal recovery from multiple myeloma-associated crystalline light chain cast nephropathy and accompanying acute kidney injury with early use of bortezomib-based therapy: a case report and literature review

Crystalline light chain cast nephropathy is a rare distinct morphologic variant of light chain cast nephropathy which is the most common renal lesion associated with multiple myeloma. It is often related to high myeloma tumor burden, severe acute kidney injury, and an unfavorable prognosis. A 79-year-old Japanese man was referred to our medical center with anemia, proteinuria, and acute exacerbation of the serum creatinine accompanying anuria. A renal biopsy showed crystalline cast filling the tubular lumens, injured tubular cells, and inflammatory cells infiltration of interstitium. Serum and urine immunofixation detected a monoclonal protein (IgA-λ and Bence-Jones Protein-λ, respectively), and bone marrow examination observed 64% of plasma cells. IgA-λ type multiple myeloma-associated crystalline light chain cast nephropathy and accompanying acute kidney injury were confirmed. Hydration and emergency hemodialysis were immediately introduced, and the treatment with bortezomib and dexamethasone was initiated. The patient showed successful recovery in renal manifestations. We suggest that early use with bortezomib-based therapy should be considered for patients with acute kidney injury caused by multiple myeloma-associated crystalline light chain cast nephropathy.

Clinicopathological Profile of Paraprotein-Associated Kidney Disease in Monoclonal Gammopathies: An Observational Study

Background Renal involvement in monoclonal gammopathies presents with different clinico-morphological patterns and can manifest at the onset or the late phase of hematological disease, or after chemotherapy. The spectrum is ever-expanding with advancements in diagnostic methods. Renal biopsy is needed for accurate diagnosis, as each of these patterns carries therapeutic and prognostic implications. Methods A total of 41 cases of monoclonal gammopathies were included in the study. Clinical, biochemical, and hematological details were obtained, and pathological variables were observed. Patients were followed till the maximum possible period, and treatment history and follow-up creatinine details were collected. Results The spectrum of renal biopsy lesions observed included light chain cast nephropathy (LCCN) n=19, amyloidosis n=11, monoclonal immunoglobulin deposition disease (MIDD) n=6, and proliferative glomerulonephritis with monoclonal immunoglobulin deposition (PGNMID) n=5; 10 of these cases can be categorized as monoclonal gammopathy of renal significance (MGRS). Acute kidney injury (AKI) (41%) is the predominant clinical presentation in general whereas the majority of amyloidosis cases presented with nephrotic and sub-nephrotic proteinuria. LCCN cases had high serum creatinine and calcium, positivity for M-spike, as well as a high FLC ratio, compared to the other types. Around 100% of LCCN and MIDD patients had myeloma and 100% of PGNMID cases had normal marrow. Conclusion More than three-fourths of patients were diagnosed with monoclonal gammopathies with biochemical and hematological workups after an initial kidney biopsy. The clinicopathological profile of these patients had a broad spectrum but there were still some consistent findings within the different types. A subgroup of patients (MGRS) had undetectable serum paraproteins but had monoclonal immunoglobulin deposition in the kidney.

Risk factors for renal impairment in patients with hematological cancer receiving antineoplastic treatment

PURPOSE

Antineoplastic treatments, mainly chemotherapy, affect the kidneys, causing toxicity, and can trigger acute and chronic kidney injuries. This study aimed to analyze the prevalence of renal disorders in patients with oncohematological neoplasms receiving antineoplastic treatment.

METHODS

This retrospective cohort study included 75 patients with hematological cancer who underwent chemotherapy between 2012 and 2018 in the Hematology Sector of the Walter Cantídeo University Hospital of the Federal University of Ceará. Sociodemographic and clinical data, blood biochemical assessment findings, and glomerular filtration rate (GFR) were analyzed using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. The data were tabulated; transferred to the Statistical Package for the Social Sciences software, version 20.0; and analyzed using Pearson's chi-square test or Fisher's exact test for categorical variables followed by a multinomial logistic regression model (p < 0.05).

RESULTS

The prevalence of renal disorders was 52.4% according to the CKD-EPI equation for GFR events. There was a significant association between the decrease in GFRs and the following variables: female sex (p = 0.002), diagnosis of multiple myeloma (p = 0.008), start of treatment within 40 days (p = 0.005), and the following antineoplastic treatments: cyclophosphamide, vincristine, and prednisone (p = 0.026); irarubicin (p = 0.032); azacytidine, dexamethasone, and cyclophosphamide (p < 0.001); zoledronic acid (p < 0.001); and pamidronate (p = 0.012). CALGB 8811 (p < 0.001) was inversely associated with a reduction in the GFR.

CONCLUSIONS

The prevalence of renal disorders was high in patients with oncohematological neoplasms receiving antineoplastic treatment. This requires periodic monitoring of the evaluation of renal function since reductions in GFRs were significantly associated with different treatment protocols used.

Histological Findings in Kidney Biopsies of Patients with Monoclonal Gammopathy—Always a Surprise

Background: The simultaneous occurrence of impaired kidney function and paraproteinemia is common in our constantly aging society. Both can be independent entities; however, renal insufficiency can also be caused by the paraprotein. We assessed all kidney biopsies in patients with monoclonal gammopathy in our clinic over the past 20 years and evaluated the histological results. Methods: Biopsies were systematically performed in nearly all patients with paraproteinemia and impaired kidney function (n = 178). The histological findings were systematically evaluated and correlated with the initial clinical diagnosis. Results: We found cast nephropathy (CN) in n = 66 (37.1%) biopsies, AL amyloidosis in n = 31 (17.4%) biopsies, monoclonal immunoglobulin deposition disease (MIDD) in n = 7 (3.9%) biopsies and other renal diseases (ORDs) in n = 74 (41.6%) biopsies. In the latter group, paraprotein-associated changes were found in 37 of 74 (50%) patients, whereas paraprotein-independent changes were found in the other half. Whereas, in the group of patients with MGUS, the findings were heterogenous, most of the patients with known multiple myeloma (MM) or B-NHL showed malignancy-associated changes in the kidney. The biopsy changed the diagnoses in a significant proportion of the patients: The group of patients with MM grew from 71 to 112 patients, whereas, in the MGUS group, only 31 of 44 patients remained. Conclusion: Kidney biopsies in patients with paraproteinemia and renal impairment show a wide range of findings that can lead to a change in diagnosis.

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.

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Management of acute kidney injury in frail patients with biopsy-proven cast nephropathy: a combined approach with chemotherapy plus Supra-hemodiafiltration with post-adsorption endogenous reinfusion

BACKGROUND

Patients with multiple myeloma often have kidney involvement with acute kidney injury which is frequently due to cast nephropathy. Hemodiafiltration with endogenous reinfusion (HFR) allows removal from the circulation of significant amounts of free light chains (FLCs) responsible for tubular damage.

METHODS

Between 2014 and 2018, 13 patients affected by multiple myeloma (64% λ chain and 36% k), including 10 cases with biopsy-proven cast nephropathy, were treated with this technique. Each patient had high free light chains levels at diagnosis: median 8586 mg/l for λ and 4200 mg/l for k, and stage III acute kidney injury (median serum creatinine 7.5 mg/dl). We initially performed daily HFR-Supra sessions and then modulated them based on renal response (mean 10 sessions/patient). At the same time, the patients also received various chemotherapy regimens, depending on their hematological criteria.

RESULTS

Forty-six percent of patients showed at least partial renal function recovery within the third month, thus allowing dialysis discontinuation; 38% remained on dialysis. Two patients died. The mean reduction rate of free light chains at the end of the HFR-Supra cycle was 85% (k) and 40% (λ), respectively. Serum albumin remained stable during the whole treatment.

DISCUSSION

In our experience, the synergistic effect of chemotherapy and HFR-Supra led to a recovery of renal function in 6 out of 13 patients presenting with severe dialysis-requiring acute kidney injury. HFR-Supra allowed stable albumin levels, with high free light chains removal rate, at a relatively low costs.

[Renal involvement in monoclonal gammopathies]

INTRODUCTION

The kidney is one of the organs most frequently affected by disease processes which produce monoclonal immunoglobins, therefore renal morphological and immunopathological alterations should be clearly recognized.

OBJECTIVE

To describe the pathological features of renal involvement in monoclonal gammopathies.

MATERIAL AND METHODS

A descriptive, retrospective and cross-sectional study of renal biopsies studied in a single center during a period of 14 years was carried out.

RESULTS

102 cases were included, of which 53% were male patients and the median age was 62.5 years (range 34 - 79). 97% of the biopsies were from native kidneys. The most frequent histopathological diagnosis (31.4%) was myeloma kidney, with kappa being the light chain most frequently deposited (65.6% of cases). AL amyloidosis was the second most common (29.4%) where the lambda chain predominated in 86.6%, followed by light chain deposition disease (20.6%) with the predominance of the kappa chain in 66.6%.

CONCLUSIONS

The most frequent renal involvement due to monoclonal gammopathies was myeloma kidney with deposition of kappa light chains, followed by AL lambda amyloidosis; these diseases were found more frequently in patients over 50 years of age.

Indications and considerations for kidney biopsy: an overview of clinical considerations for the non-specialist

Around 3 million people in the UK have chronic kidney disease and 20% of hospital admissions are complicated by acute kidney injury. Decline in kidney function is not a diagnosis; it is essential to identify and treat underlying causes of acute and chronic kidney disease to either achieve recovery or slow the decline of kidney function. Thorough clinical assessment and simple investigations help determine the category of kidney injury (pre-renal, intrinsic or post-renal) and inform the need for kidney biopsy, which can provide significant information in the evaluation of suspected intrinsic kidney disease, supporting diagnosis, guiding prognosis and management, and identifying disease relapse. The procedure is invasive and not without risk, which although small has the potential to be both organ- and life-threatening. This review outlines roles of kidney biopsy for the non-specialist, with focus of its role in patients with diabetes, lupus, myeloma and in the older patient.

Clinicopathological features and outcomes of coexistent light chain cast nephropathy and light chain deposition disease in patients with newly diagnosed multiple myeloma

AIMS

A varying proportion of patients with multiple myeloma suffer from more than one type of kidney disease simultaneously, of which the most common pattern is coexistent light chain cast nephropathy and light chain deposition disease (LCCN+LCDD). We investigated clinicopathological characteristics and outcomes of LCCN+LCDD in comparison with pure LCCN and pure LCDD.

METHODS

We retrospectively analysed 45 newly diagnosed multiple myeloma patients with pure LCCN (n=26), LCCN +LCDD (n=9) and pure LCDD (n=10) between 2000 and 2019 at Peking University First Hospital.

RESULTS

Pathologically, patients with LCCN+LCDD were more likely to have λ light chain isotype and presented atypical features of LCDD including less nodular glomerulosclerosis and less deposit distribution than patients with pure LCDD. In clinical characteristics, patients with LCCN +LCDD and patients with pure LCCN shared similar features. The death-censored renal survival in patients with LCCN +LCDD was similar to patients with pure LCCN but worse than patients with pure LCDD, but the overall survival was much better than patients with LCCN alone and similar to patients with pure LCDD. For patients with pure LCCN, the independent predictor of death-censored renal survival was lactate dehydrogenase, and the independent predictors of overall survival were the mean number of casts and serum albumin.

CONCLUSIONS

Patients with LCCN+LCDD had similar renal outcome compared with patients with pure LCCN but the overall survival is much better. Thus, for patients with LCCN, especially those with λ restriction, pathologists should carefully evaluate the kidney specimens to exclude the possibility of combined LCDD.

Monoclonal Immunoglobulin-Associated Renal Lesions in Patients with Newly Diagnosed Multiple Myeloma: A Report from a Single Center

Background

Monoclonal immunoglobulin-associated renal lesions in patients with newly diagnosed myeloma vary. We aimed to determine the pathological spectrum and analyze associated prognostic factors.

Methods

Fifty-six patients with newly diagnosed multiple myeloma and biopsy-proven renal lesions were enrolled. Kidney biopsies were reanalyzed, and the baseline clinical characteristics, treatments and outcomes were recorded.

Results

Fifty-one patients had monoclonal immunoglobulin-associated renal lesions, with myeloma cast nephropathy (MCN) being the most common pattern. We divided our cohort into pure MCN, MCN+ other pathologies and non-MCN. Patients with MCN had more severe renal injury than those with non-MCN. In our cohort, none of the patients with pure MCN or MCN + other pathologies presented with nephrotic syndrome. Patients with non-MCN had better renal and overall survival than those with pure MCN but similar survivals to those with MCN + other pathologies. Number of myeloma casts (HR 1.08, p = 0.012) was the only independent prognostic factor for renal survival. Male sex (HR: 3.64; p = 0.015) and number of casts (HR: 1.17; p = 0.001) were independent prognostic factors for overall survival.

Conclusion

Patients with MCN had more severe renal injury than those with non-MCN. Patients with non-MCN had better renal and overall outcomes than those with pure MCN, but their outcomes were similar to those with MCN + other pathologies. The independent predictors of overall survival were male sex and number of myeloma casts.

The Proximal Tubule Toxicity of Immunoglobulin Light Chains

Plasma and B cells dyscrasias that overproduce monoclonal immunoglobulin free light chains (FLCs) affect the kidney frequently in various ways. The hematologic dyscrasia responsible for the production of FLCs may or may not meet the criteria for cancer, such as multiple myeloma (MM) or lymphoma, or may remain subclinical. If there is overt malignancy, the accompanying kidney disorder is called myeloma- or lymphoma-associated. If the dyscrasia is subclinical, the associated kidney disorders are grouped as monoclonal gammopathy of renal significance. Glomeruli and tubules may both be involved. The proximal tubule disorders comprise a spectrum of interesting syndromes, which range in severity. This review focuses on the recent insights gained into the patterns and the mechanisms of proximal tubule toxicity of FLCs, including subtle transport disorders, such as proximal tubule acidosis, partial or complete Fanconi syndrome, or severe acute or chronic renal failure. Histologically, there may be crystal deposition in the proximal tubule cells, acute tubule injury, interstitial inflammation, fibrosis, and tubule atrophy. Specific structural alterations in the V domain of FLCs caused by somatic hypermutations are responsible for crystal formation as well as partial or complete Fanconi syndrome. Besides crystal formation, tubulointerstitial inflammation and proximal tubulopathy can be mediated by direct activation of inflammatory pathways through cytokines and Toll-like receptors due to cell stress responses induced by excessive FLC endocytosis into the proximal tubule cells. Therapy directed against the clonal source of the toxic light chain can prevent progression to more severe lesions and may help preserve kidney function.

Kinetics of Renal Function during Induction in Newly Diagnosed Multiple Myeloma: Results of Two Prospective Studies by the German Myeloma Study Group DSMM

Simple Summary

Renal insufficiency is frequently seen in newly diagnosed multiple myeloma and can be due to the disease itself but also caused by medical interventions or infections. Patients with severe renal insufficiency are known to have an adverse prognosis, but recently, it was shown that even moderately impaired kidney function can have long-term sequelae. Achieving quick disease control by effective antimyeloma therapy can lead to the recovery of renal function. We investigated the kidney-specific variables in a large cohort of 770 myeloma patients receiving three different three-drug regimens for initial myeloma treatment to learn more about the differential effects on kidney function in an early disease phase. All regimens had a positive impact on kidney function without a difference in the proportion of patients who reached normal renal function after three cycles. Interestingly, patients who received bortezomib, lenalidomide, and dexamethasone tended to have higher risk for a worse renal function following induction when compared to the initial values.

Abstract

Background: Preservation of kidney function in newly diagnosed (ND) multiple myeloma (MM) helps to prevent excess toxicity. Patients (pts) from two prospective trials were analyzed, provided postinduction (PInd) restaging was performed. Pts received three cycles with bortezomib (btz), cyclophosphamide, and dexamethasone (dex; VCD) or btz, lenalidomide (len), and dex (VRd) or len, adriamycin, and dex (RAD). The minimum required estimated glomerular filtration rate (eGFR) was >30 mL/min. We analyzed the percent change of the renal function using the International Myeloma Working Group (IMWG) criteria and Kidney Disease: Improving Global Outcomes (KDIGO)-defined categories. Results: Seven hundred and seventy-two patients were eligible. Three hundred and fifty-six received VCD, 214 VRd, and 202 RAD. VCD patients had the best baseline eGFR. The proportion of pts with eGFR <45 mL/min decreased from 7.3% at baseline to 1.9% PInd (p < 0.0001). Thirty-seven point one percent of VCD versus 49% of VRd patients had a decrease of GFR (p = 0.0872). IMWG-defined “renal complete response (CRrenal)” was achieved in 17/25 (68%) pts after VCD, 12/19 (63%) after RAD, and 14/27 (52%) after VRd (p = 0.4747). Conclusions: Analyzing a large and representative newly diagnosed myeloma (NDMM) group, we found no difference in CRrenal that occurred independently from the myeloma response across the three regimens. A trend towards deterioration of the renal function with VRd versus VCD may be explained by a better pretreatment “renal fitness” in the latter group.

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.

A non-invasive differential diagnostic model for light chain cast nephropathy in newly diagnosed multiple myeloma patients with renal involvement: a multicenter study

OBJECTIVE

Light chain cast nephropathy is the most common form of renal lesion in multiple myeloma. Kidney impairment caused by light chain cast nephropathy can be reversed and survival can be improved if early diagnosis is available. It is thus of imperative importance to develop a non-invasive method to diagnose light chain cast nephropathy once the kidney biopsy is not always applicable.

METHODS

We consecutively screened newly diagnosed multiple myeloma patients with kidney biopsies from 4 centers in China. Kidney pathologies were reviewed and clinical presentations were recorded. Then a diagnostic model was established by logistic regression and the predictive values were assessed.

RESULTS

Between 1 June 1999 and 30 June 2019, a kidney biopsy was performed in 94 patients with newly diagnosed multiple myeloma, and light chain cast nephropathy was the most common pattern, seen in 52% of biopsied patients. The diagnostic model was established by multivariate logistic regression analysis as P(z) = 1/(1 + e^-z) and z = - 0.093 Hemoglobin (g/L) + 0.421 Serum albumin (g/L) + 3.463 Acute kidney injury (0/1) - 9.207 High-density lipoprotein (mmol/L). If P(z) ≥ 0.55, the diagnosis pointed to light chain cast nephropathy; if P(z) < 0.55, the diagnosis favored non-light chain cast nephropathy. The area under the receiver operating characteristic curves was 0.981 (95% CI 0.959, 1.000). The model had a sensitivity of 93.9%, a specificity of 95.6%, a positive predictive value of 96.0%, a negative predictive value of 94.0%, and a total consistency of 95.0%.

CONCLUSION

We built a novel, non-invasive diagnostic model through a multicenter study, which may be helpful in the diagnosis of light chain cast nephropathy in newly diagnosed multiple myeloma patients.

[Autologous haematopoietic stem cell transplantation in patients with multiple myeloma complicated by dialysis-dependent renal failure]

AIM

To assess the safety and efficacy of autologous haematopoietic stem cell transplantation (auto-HSCT) in multiple myeloma (MM) patients with dialysis-dependent renal failure.

MATERIALS AND METHODS

During a period from May 2010 to December 2016 fourteen MM patients with dialysis-dependent renal failure aged 48 to 65 years underwent auto-HSCT. After the induction therapy complete response, very good partial response, partial response were documented in 64, 29, 7% of patients, respectively. In no case was a renal response achieved. Haematopoietic stem cell mobilization in most patients (13/14) was performed according to the scheme: G-CSF 10 g/kg. Melphalan in 3 dosages was used as pre-transplant conditioning: 100, 140 and 200 mg/m2; 13 patients underwent a single and in one case underwent a tandem auto-HSCT against the background of hemodialysis. Evaluation of the antitumor and renal response was assessed on the 100th day after auto-HSCT. Subsequently, against the background of programmed hemodialysis and in the setting of high-dosed melphalan (100200 mg/m2), 13 patients underwent a single and one patient underwent a tandem auto-HSCT. At +100 days after auto-HSCT, an antitumor response and renal response were assessed.

RESULTS

The period of agranulocytosis after auto-HSCT was from 5 to 12 days (median 8,5) and was accompanied by infectious complications, cardiac and neurological dysfunctions. At +100 days after auto-HSCT, the complete response was confirmed in 71% patients and very good partial response was confirmed in 29% patients. The minimal renal response was registered in 2 patients (14%), hemodialysis was stopped. The transplant-related mortality was absent. After a median follow-up of 53 months 5-year progression-free survival was 59%, and overall survival was 93%.

CONCLUSION

Carrying out auto-HSCT in patients with dialysis-dependent renal failure contributed to the achievement of a minimal renal response in 14% of cases, which allowed these patients to stop hemodialysis. Patients whose conditioning regimen was performed using melphalan at a dose of 200 mg/m2showed more frequent complications in the early post-transplant period compared to patients who received a lower dose of melphalan (100140 mg/m2). Auto-HSCT in MM patients with dialysis-dependent renal failure is a feasible and effective treatment method, which in some cases contributes to independence from hemodialysis.

[Morphological and immunohistochemical predictors of renal response to therapy patients with myeloma cast nephropathy and dialysis-dependent acute kidney injury]

AIM

Reveal morphological and immunohistochemical predictors of reversibility of dialysis-dependent acute kidney injury (AKI) in patients with myeloma cast nephropathy (MCN) based on the study of kidney biopsy.

MATERIALS AND METHODS

Renal pathological findings were studied in 36 patients with MCN and dialysis-dependent stage 3 AKI (AKIN, 2012). The study of biopsy samples was performed by a semi-quantitative and quantitative analysis using computer morphometry. The expression of E-cadherin, vimentin and-smooth muscle actin was determined immunohistochemically in the tubular cells and interstitium. Induction therapy for 26 patients was carried out to bortezomib-based programs; in 10 patients other schemes were used. A comparative analysis of morphological changes in nephrobiopathy depending on the renal response was performed in patients with achieved hematologic remission.

RESULTS

Improved renal function was observed only in patients with hematologic response to therapy. There were no differences in the number of sclerotic glomeruli, protein casts, the area of inflammatory interstitial infiltration, and the degree of acute tubular damage in patients with and without renal response. In patients with renal response compared with patients without improving renal function, the area of interstitial fibrosis was less (24.9% and 45.9%, respectively;p=0.001), and the area of E-cadherin expression was larger (15.9% and 7.1%, respectively;p=0.006). Interstitial fibrosis of 40% or more and/or the area of expression of E-cadherin less than 10% of the area of tubulo-interstitium have an unfavorable prognostic value in achieving a renal response in MCN.

CONCLUSION

If the interstitial fibrosis area is 40% or more and the expression area of E-cadherin is less than 10%, the probability of the absence of a renal response is 93.3% (OR=24.5) even when a hematological response to induction therapy is achieved. The number of protein casts, the prevalence of acute tubular damage and inflammatory interstitial infiltration have not prognostic value.

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.

Plasma exchange combined with bortezomib-based chemotherapy is effective for early renal recovery in a patient with IgD-λ type multiple myeloma

The immunoglobulin (Ig) D type is a rare variant of multiple myeloma (MM), that accounts for 1-2% of all cases. Compared to the more common types of MM, IgD MM is known to have more severe symptoms at presentation, and a poorer prognosis. A woman was admitted to our hospital for severe acute kidney disease and disorder (AKD) and back pain, and was started on hemodialysis. The renal biopsy revealed light chain cast nephropathy. She was diagnosed with IgD-λ MM based on Bence-Jones protein expression and high IgD serum levels, and started bortezomib therapy with plasma exchange (PE). After three sessions of PE, the serum free light chain levels decreased by 92%, and she was withdrawn from dialysis. The patient underwent autologous transplantation and is still in remission, demonstrating the benefits of a bortezomib-based regimen in combination with PE for IgD MM with AKD.

KIDNEY DISEASE ASSOCIATED WITH MONOCLONAL GAMMOPATHIES: SINGLE-CENTER STUDY

INTRODUCTION:Renal injury associated with monoclonal gammopathies (MG) is an area of interest of practical onconephrology. Prevalence, spectrum and renal outcome as far as approaches to treatment in this pathological entity, particularly in Russian population, still remain unclear and need refinement. AIM: Analysis of the prevalence, spectrum, treatment approaches and renal outcome in kidney injury associated with monoclonal gammopathies (MG).

PATIENTS AND METHODS:Patients with MG and renal injury proven by kidney biopsies from 01.01.2011 till 01.05.2018 were enrolled into this one-center prospective study (n=119). Cases of MG of undetermined significance and non-amyloid kidney lesions were estimated as MG of renal significance (MGRS). Treatment approaches, haematological and renal responses were analysed. Worsening of kidney function was estimated as eGFR decrease >25 % from initial value or initiation of renal replacement treatment (RRT), improving – as eGFR increase >25 % from the initial value or the discontinuation of RRT. Other cases were determined as stable kidney function. Kidney outcome was determined in RRT initiation or eGFR<15 ml/min/1,73m2 at the end of follow-up. Long-term kidney outcome was estimated by Kaplan-Meier survival analysis. The median follow-up period was 12 (2; 27) months.

RESULTS.Prevalence of kidney injury associated with MG among all performed kidney biopsies was 7,5 %, MGRS – 0,94 %. Multiple myeloma (MM), AL-amyloidosis and lymphoproliferative disorder (LPD) were diagnosed in 39, 55 and 10 patients, respectively. Prevalence of kidney injury types was the following: Al-amyloidosis (53 %); cast nephropathy (12 %); light chain deposition disease (12 %); C3-glomerulopathy (3 %); proliferative glomerulonephritis (GN) with monoclonal immunoglobulin deposits (3 %); cryoglobulinemic GN (2 %); thrombotic microangiopathy (2 %); podocytopathy (2 %); acute tubular necrosis – 2 %; immunotactoid GN (1 %); fibrillary GN (1 %); proximal tubulopathy (1 %), combination of different types (6 %). Patients mostly were treated with bortezomib and dexamethasone. Autologous stem cell transplantation was performed in 13 patients. Haematological response was achieved in 48,8 %, 45,4 % and 46,7 % of patients with MM, AL-amyloidosis and MGRS, respectively. Worsening of kidney function was registered in 11,1 % of MM and in 37,2 % of AL-amyloidosis; improving or stable kidney function was in 88,9 % and 62,7 % MM and AL-amyloidosis patients, respectively. In MGRS improving (20 %) and stable kidney function (80 %) were detected. Four-years cumulative renal survival in MM, AL-amyloidosis, MGRS and LPD groups was 63 %, 54 %, 80 % and 39 %, respectively, and does not differ between 4 groups.

CONCLUSION:MG-associated kidney disease represented by diverse clinical and morphological patterns is standard problem in routine clinical practice. It is associated with inferior renal outcome and requires a practical implementation of highly-specialized interdisciplinary approach to diagnostics and treatment.

Treatment of multiple myeloma with renal involvement: the nephrologist's view

Renal injury is a common complication in multiple myeloma (MM). In fact, as many as 10% of patients with MM develop dialysis-dependent acute kidney injury related to increased free light chain (FLC) production by a plasma cell clone. Myeloma cast nephropathy (MCN) is the most prevalent pathologic diagnosis associated with renal injury, followed by light chain deposition disease and light chain amyloidosis. Several FLC removal techniques have been explored to improve kidney disease in MM but their impact on renal clinical outcomes remains unclear. According to the evidence, high cut-off haemodialysis should be restricted to MM patients on chemotherapy with histological diagnosis of MCN and haemodialysis requirements. From our perspective, more efforts are needed to improve kidney outcomes in patients with MM and renal failure.

Intratubular amyloid in light chain cast nephropathy is a risk factor for systemic light chain amyloidosis

Light chain cast nephropathy is the most common form of kidney disease in patients with multiple myeloma. Light chain casts may occasionally show amyloid staining properties, that is, green birefringence after Congo red staining. The frequency and clinical significance of this intratubular amyloid are poorly understood. Here, we retrospectively assessed the clinicopathological features of 60 patients with histologically proven light chain cast nephropathy with a specific emphasis on intratubular amyloid, especially, its association with extrarenal systemic light chain amyloidosis. We found intratubular amyloid in 17 cases (17/60, 28%) and it was more frequent in patients with λ light chain gammopathy (13/17 in the 'intratubular amyloid' group vs 19/43 in the 'no intratubular amyloid' group, P=0.02). Pathological examination of extrarenal specimens showed that intratubular amyloid was significantly associated with the occurrence of systemic light chain amyloidosis (5/13 in the 'intratubular amyloid' group vs 0/30 in the 'no intratubular amyloid' group, P=0.001). Our results indicate that first, intratubular amyloid is not a rare finding in kidney biopsies of patients with light chain cast nephropathy, and, second, it reflects an amyloidogenic capacity of light chains that can manifest as systemic light chain amyloidosis. Thus, intratubular amyloid should be systematically screened for in kidney biopsies from patients with light chain cast nephropathy and, if detected, should prompt a work-up for associated systemic light chain amyloidosis.

Effect of High-Cutoff Hemodialysis vs Conventional Hemodialysis on Hemodialysis Independence Among Patients With Myeloma Cast Nephropathy: A Randomized Clinical Trial

Importance

Cast nephropathy is the main cause of acute kidney injury in multiple myeloma and persistent reduction in kidney function strongly affects prognosis. Strategies to rapidly remove nephrotoxic serum-free light chains combined with novel antimyeloma agents have not been evaluated prospectively.

Objective

To compare the hemodialysis independence rate among patients newly diagnosed with myeloma cast nephropathy treated with hemodialysis using a high-cutoff dialyzer (with very large membrane pores and high permeability to immunoglobulin light chains) or a conventional high-flux dialyzer (with small pores and lower permeability).

Design, Setting, and Participants

Randomized clinical trial involving 98 patients with biopsy-proven myeloma cast nephropathy requiring hemodialysis treated at 48 French centers between July 2011 and June 2016; the final date of follow-up was June 29, 2016.

Interventions

Intensive hemodialysis (eight 5-hour sessions over 10 days) with either a high-cutoff dialyzer (46 patients) or a conventional high-flux dialyzer (48 patients). All patients received the same chemotherapy regimen of bortezomib and dexamethasone.

Main Outcomes and Measures

Primary end point was hemodialysis independence at 3 months; secondary end points: hemodialysis independence rates at 6 and 12 months, hemodialysis- and chemotherapy-related adverse events, and death.

Results

Among 98 randomized patients, 94 (96%) (median age, 68.8 years [interquartile range, 61.2-75.3 years]; 45% women) were included in the modified intent-to-treat analysis. The hemodialysis independence rate at 3 months was 41.3% (n = 19) in the high-cutoff hemodialysis group vs 33.3% (n = 16) in the conventional hemodialysis group (between-group difference, 8.0% [95% CI, -12.0% to 27.9%], P = .42); at 6 months, the rate was 56.5% (n = 26) vs 35.4% (n = 17), respectively (between-group difference, 21.1% [95% CI, 0.9% to 41.3%], P = .04); and at 12 months, the rate was 60.9% (n = 28) vs 37.5% (n = 18) (between-group difference, 23.4% [95% CI, 3.2% to 43.5%], P = .02). The incidence of hemodialysis-related adverse events was 43% in the high-cutoff hemodialysis group vs 39% in the conventional hemodialysis group; chemotherapy-related serious adverse events, 39% vs 37%, respectively; and at 12 months, 9 patients vs 10 patients died.

Conclusions and Relevance

Among patients with myeloma cast nephropathy treated with a bortezomib-based chemotherapy regimen, the use of high-cutoff hemodialysis compared with conventional hemodialysis did not result in a statistically significant difference in hemodialysis independence at 3 months. However, the study may have been underpowered to identify an early clinically important difference.

Trial Registration

clinicaltrials.gov Identifier: NCT01208818.

Paraprotein-Related Kidney Disease: Evaluation and Treatment of Myeloma Cast Nephropathy

Nearly 50% of patients with multiple myeloma develop renal disease, most commonly from AKI caused by cast nephropathy. Development of AKI is associated with poor 1-year survival and reduces the therapeutic options available to patients. There is a great need for more effective therapies. Cast nephropathy is caused by the interaction and aggregation of filtered free light chains and Tamm-Horsfall protein causing intratubular obstruction and damage. The key to treating cast nephropathy is rapid lowering of free light chains, because this correlates with renal recovery. Newer chemotherapy agents rapidly lower free light chains and have been referred to as renoprotective. There is additional great interest in using extracorporeal therapies to remove serum free light chains. Small trials initially showed benefit of therapeutic plasma exchange to improve renal outcomes in cast nephropathy, but a large randomized trial of therapeutic plasma exchange failed to show benefit. A newer technique is extended high-cutoff hemodialysis. This modality uses a high molecular weight cutoff filter to remove free light chains. To date, trials of high-cutoff hemodialysis use in patients with cast nephropathy have been encouraging. However, there are no randomized trials showing the benefit of high-cutoff hemodialysis when used in addition to newer chemotherapeutic regimens. Until these studies are available, high-cutoff hemodialysis cannot be recommended as standard of care.

Paraprotein-Related Kidney Disease: Kidney Injury from Paraproteins-What Determines the Site of Injury?

Disorders of plasma and B cells leading to paraproteinemias are associated with a variety of renal diseases. Understanding the mechanisms of injury and associated nephropathies provides a framework that aids clinicians in prompt diagnosis and appropriate adjunctive treatment of these disorders. Glomerular diseases that may be associated with paraproteinemias include amyloid deposition, monoclonal Ig deposition disease, proliferative GN with monoclonal Ig deposits, C3 glomerulopathy caused by alterations in the complement pathway, immunotactoid glomerulopathy, fibrillary GN, and cryoglobulinemia. Tubular lesions include the classic Fanconi syndrome, light-chain proximal tubulopathy, interstitial fibrosis, and cast nephropathy. These paraproteinemic renal diseases are distinct in their pathogenesis as well as their urinary and kidney biopsy findings. Renal pathology is usually initiated by deposition and direct involvement of the intact monoclonal Ig or Ig fragments with resident cells of the nephron. Our review summarizes current insights into the underlying molecular pathogenesis of these interesting kidney lesions.

Monotypic plasma cell interstitial nephritis as the only clinical manifestation in a patient with previously undiagnosed indolent multiple myeloma: A case report

INTRODUCTION

Predominantly monotypic plasma cell infiltrates are an uncommon renal finding in patients with malignant lymphoplasmacytic proliferation.

CASE PRESENTATION

We report the case of a 52-year-old man with chronic kidney disease and significant proteinuria associated with a monoclonal immunoglobulin spike (IgGκ). Kidney biopsy revealed the presence of atypical multinucleated CD138 plasma cells with voluminous nuclei stained exclusively with a κ antibody. Electron microscopy showed mesangial and segmental parietal electron-dense, nonorganized hyaline deposits without immunogold labeling for the κ light chain. The bone marrow aspirate revealed 6% of apparently mature plasmocytes without dystrophy. We therefore concluded that the patient had an indolent multiple myeloma with specific renal involvement in the form of malignant monotypic interstitial plasmacytic infiltration. We initiated a specific chemotherapy regimen including bortezomib-cyclophosphamide-dexamethasone. After 4 months of follow-up, creatinine levels had improved slightly and free κ light-chain levels had decreased significantly within the normal range.

CONCLUSION

This case highlights the need to consider neoplastic interstitial plasma cell infiltration systematically in patients diagnosed with an apparently benign monoclonal gammopathy and to consider adaptation of the chemotherapy regimen, to improve renal function.

Therapeutic Efficacy and Cost Effectiveness of High Cut-Off Dialyzers Compared to Conventional Dialysis in Patients with Cast Nephropathy

Background

High Cut-Off (HCO) dialysis membranes efficiently reduce serum free light chain (FLC) concentrations and may improve renal recovery and survival from multiple myeloma (MM) associated renal failure with cast nephropathy. However, clinical trials comparing dialysis with HCO versus conventional filters are lacking. The aim of this study was to assess clinical outcomes and economic impact of HCO dialyzers compared to conventional hemodialysis membranes in cast nephropathy.

Methods

Multicenter retrospective analysis of 19 patients treated for renal failure from FLC associated cast nephropathy with standard induction chemotherapy (bortezomib/dexamethasone). We compared hemodialysis treatment with High Cut-Off (n = 12) versus conventional dialyzers (n = 7). Primary endpoint was survival; secondary endpoints were renal recovery, renal function and treatment costs.

Results

At 12 months, patient survival was 25% in the HCO group versus 0% in controls (p = NS). A tendency towards faster renal recovery (p = 0.066) and better renal function at 3, 6 and 12 months (p = 0.109) after diagnosis of MM was noted in the HCO group. Complete renal response rate was achieved in 10.5 and 0% of HCO and control patients, respectively, partial renal response in 15.8 and 5.3%, and minor renal response in 26.3 and 15.8%, respectively. Both patient survival and renal recovery were significantly correlated with the extent of free light chain (FLC) reduction in serum. Median treatment costs were CHF 230’000 and 223’000 (p = NS) in the HCO and control group, respectively.

Conclusions

Hemodialysis treatment with HCO membranes for cast nephropathy tended towards better survival as well as faster and better recovery of renal function versus conventional dialyzers. Moreover, total medical costs were comparable between groups. In the absence of results from randomized prospective trials on this topic, the use of HCO dialyzers in patients with renal failure from cast nephropathy may be recommended. Prospective randomized trials are required.