Renal involvement in monoclonal gammopathy

Current status and prospect of anti-amyloid fibril therapy in AL amyloidosis

Amyloid light-chain (AL) amyloidosis is a rare hematological disease that produces abnormal monoclonal immunoglobulin light chains to form amyloid fibrils that are deposited in tissues, resulting in organ damage and dysfunction. Advanced AL amyloidosis has a very poor prognosis with a high risk of early mortality. The combination of anti-plasma cell therapy and amyloid fibrils clearance is the optimal treatment strategy, which takes into account both symptoms and root causes. However, research on anti-amyloid fibrils lags far behind research on anti-plasma cells, and there is currently no approved treatment that could clear amyloid fibrils. Nevertheless, anti-amyloid fibril therapies are being actively investigated recently and have shown potential in clinical trials. In this review, we aim to outline the preclinical work and clinical efficacy of fibril-directed therapies for AL amyloidosis.

[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.

Clinicopathological characteristics of patients with paraproteinemia and renal damage

Background

This study aimed to analyze the clinicopathological characteristics of patients with paraproteinemia and renal damage.

Methods

Ninety-six patients from 2014 to 2018 with paraproteinemia and renal damage were enrolled and the clinical data, renal pathology, treatment and prognosis data were collected.

Results

A total of 96 patients (54 male and 42 female), accounting for 2.7% of all renal biopsies, were enrolled in this study. Among them, 42 were monoclonal gammopathy of renal significance (MGRS), 21 were renal monotypic immunoglobulin alone (renal monoIg), and 19 were monoclonal gammopathy of undetermined significance (MGUS). Individuals with multiple myeloma (MM) accounted for the fewest number of patients (n  =  14). In the MGRS group, the main diseases were amyloidosis (n  =  25) and cryoglobulinemic glomerulonephritis (n  =  7), while in the MM group, the main diseases were cast nephropathy (n  =  9) and light chain deposit disease (n  =  3). In the MGUS group, it was mainly IgA nephropathy (IgAN, n  =  10) and idiopathic membranous nephropathy (n  =  5); while in the renal monoIg group, most of the cases were IgAN (n  =  19). Chemotherapy was mainly administered to patients in the MM group, while immunosuppression therapy was mostly administered to patients in the renal monoIg group. Most patients with renal monoIg exhibited a major response, followed by the patients with MGUS and MGRS, while most of the patients with MM had a partial response but none had a major response. Approximately more than half (57.1%) of the patients with MM progressed to end-stage renal disease (ESRD), followed by MGRS (33.3%); however, the mortality rate was low in both the MGRS and MM groups. The survival analysis reviewed that serum creatinine, hemoglobin levels, and the serum κ/λ ratio were independent risk factors for ESRD in patients with MGRS.

Conclusions

The clinicopathological changes in patients with MGRS were between those in patients with MM and MGUS. The treatment for MGRS and MM was more intensive, and the overall mortality rate was low. Both MGUS and renal monoIg alone exhibited slighter clinicopathological features than MGRS and MM, and the treatment was focused mostly on primary renal diseases.

Bortezomib Maintenance for the Treatment of Monoclonal Gammopathy of Renal Significance

Monoclonal gammopathy of renal significance (MGRS) defines renal diseases resulting from the nephrotoxic effects of monoclonal proteins secreted from non-malignant clonal B cells or plasma cells, that do not meet criteria for multiple myeloma, Waldenstrom’s macroglobulinemia, chronic lymphocytic leukemia, or lymphomas. Renal disease in MGRS can result from monoclonal immunoglobulin deposition to different parts of the kidney and includes a wide spectrum of glomerular, tubulointerstitial and vascular renal diseases. Recognizing MGRS is important because renal outcomes are poor and treatments targeting the underlying clonal disease have been associated with improved renal survival. In this case report, we present a case of a patient with proliferative glomerulonephritis with monoclonal immunoglobulin deposits (PGNMID) subtype of MGRS who underwent a phased clone directed treatment of induction and extended maintenance therapy to achieve renal response.

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.

The role of the immune system in kidney disease

The immune system and the kidneys are closely linked. In health the kidneys contribute to immune homeostasis, while components of the immune system mediate many acute forms of renal disease and play a central role in progression of chronic kidney disease. A dysregulated immune system can have either direct or indirect renal effects. Direct immune-mediated kidney diseases are usually a consequence of autoantibodies directed against a constituent renal antigen, such as collagen IV in anti-glomerular basement membrane disease. Indirect immune-mediated renal disease often follows systemic autoimmunity with immune complex formation, but can also be due to uncontrolled activation of the complement pathways. Although the range of mechanisms of immune dysregulation leading to renal disease is broad, the pathways leading to injury are similar. Loss of immune homeostasis in renal disease results in perpetual immune cell recruitment and worsening damage to the kidney. Uncoordinated attempts at tissue repair, after immune-mediated disease or non-immune mediated injury, result in fibrosis of structures important for renal function, leading eventually to kidney failure. As renal disease often manifests clinically only when substantial damage has already occurred, new diagnostic methods and indeed treatments must be identified to inhibit further progression and promote appropriate tissue repair. Studying cases in which immune homeostasis is re-established may reveal new treatment possibilities.

Light chain amyloidosis: Where are the light chains from and how they play their pathogenic role?

Amyloid light-chain (AL) amyloidosis is a plasma-cell dyscrasia, as well as the most common type of systematic amyloidosis. Pathogenic plasma cells that have distinct cytogenetic and molecular properties secrete an excess amount of amyloidogenic light chains. Assisted by post-translational modifications, matrix components, and other environmental factors, these light chains undergo a conformational change that triggers the formation of amyloid fibrils that overrides the extracellular protein quality control system. Moreover, the amyloidogenic light-chain itself is cytotoxic. As a consequence, organ dysfunction is caused by both organ architecture disruption and the direct cytotoxic effect of amyloidogenic light chains. Here, we reviewed the molecular mechanisms underlying this sequence of events that ultimately leads to AL amyloidosis and also discuss current in vitro and in vivo models, as well as relevant novel therapeutic approaches.

Renal lesions associated with monoclonal gammopathies of undetermined significance: clinical forms, mechanisms of development, approaches to treatment

The term «monoclonal gammopathies of undetermined significance» (MGUS) was introduced by R. Kyle in 1978 to designate the condition characterized by the presence ofsmall amounts ofM-protein in the serum. In some patients, such condition remains benign for a long time but predetermines for the development of multiple myeloma and other B-lymphocytic tumours. Also, it can provoke non-cancerous diseases due to the toxic action of monoclonal proteins (immunoglobulins and free light chains) on various organs, especially kidneys. MGUS-associated renal lesions include glomerulopathies with organized deposits, such as AL-amyloidosis (amyloid light chain of immunoglobulin), cryoglobulinic and immunotactoid glomerulonephritis, and with unorganized deposits (light chain deposition and proliferative forms of idiopathic glomerulonephritis. The available experimental data throw light on the possible mechanisms of renal lesions. We summarized the literature data and original observations to describe methods for differential diagnostics of MGUS-associated renal lesions including the highly sensitive test for free light chine identification (Freelite method) and principles of pathogenetic treatment by the impact on the pathological B-cell clone.

Paraprotein-Related Kidney Disease: Diagnosing and Treating Monoclonal Gammopathy of Renal Significance

Paraprotein-related kidney disease represents a complex group of diseases caused by an abnormal paraprotein secreted by a clone of B cells. The disease manifestations range from tubulopathies, such as the Fanconi syndrome, to a spectrum of glomerular diseases that can present with varying degrees of proteinuria and renal dysfunction. Diagnosis of these diseases can be challenging because of the wide range of manifestations as well as the relatively common finding of a serum paraprotein, especially in elderly patients. Thus, renal biopsy along with detailed hematologic workup is essential to link the presence of the paraprotein to the associated renal disease. Recent advances in treatment with more effective and targeted chemotherapies, as well as stem cell transplantation, have improved the renal and overall prognosis for many of these disorders.

Hematopoietic Cell and Renal Transplantation in Plasma Cell Dyscrasia Patients

Gammopathies, multiple myeloma, and amyloidosis are plasma dyscrasias characterized by clonal proliferation and immunoglobulin overproduction. Renal impairment is the most common and serious complication with an incidence of 20–30% patients at the diagnosis. Kidney transplant has not been considered feasible in the presence of plasma dyscrasias because the immunosuppressive therapy may increase the risk of neoplasia progression, and paraproteins may affect the graft. However, recent advances in clinical management of multiple myeloma and other gammopathies allow considering kidney transplant as a possible alternative to dialysis. Numerous evidence indicates the direct relationship between hematological remission and renal function restoring. The combination of kidney and hematopoietic cell transplant has been reported as a promising approach to reestablish end-organ function and effectively treat the underlying disease. This review describes current protocols used to perform kidney transplantation in patients with plasma dyscrasias.