Monoclonal gammopathy of renal significance (MGRS): Real-world data on outcomes and prognostic factors

The Mayo MGRS Prediction Tool calculates the risk of finding monoclonal gammopathy of renal significance in a kidney biopsy in patients with monoclonal gammopathy

INTRODUCTION

Monoclonal gammopathy of renal significance (MGRS) is increasingly recognized as an important causes of kidney failure. A kidney biopsy remains an important diagnostic measure. However, a kidney biopsy is not without risks. Here, we devised the Mayo MGRS Prediction Tool to assess the probability of finding MGRS in patients with chronic kidney disease with monoclonal gammopathy (MG).

METHODS

We included patients from 2013 to October 2023 who underwent a kidney biopsy at the Mayo Clinic excluding those whose hematological condition required specific treatment due to tumor burden such as multiple myeloma.

RESULTS

Of 280 patients, 92 (32.9%) had MGRS lesions with amyloid light chain or primary amyloidosis being the most common lesion in 38 patients (41.3%). We performed multivariable logistic regression with forward variable selection to fit the model. The final model included eight predictors: diabetes, affected/unaffected free light chain ratio, urinary protein (g/24 hours), positive urine protein electrophoresis or immunofixation electrophoresis, serum creatinine, C3 level (mg/dL), hematuria, and systolic blood pressure. The calculated and optimism corrected area under the curve was 0.896 and 0.836 respectively. The decision curve analysis showed that the model provided net benefit across all thresholds. A threshold probability of 0.10 was 98.9% sensitive and 50.5% specific and threshold probability of 0.25 was 88.0% sensitive and 70.2% specific. The model was validated using an external cohort of 109 patients from the University of Minnesota with good performance.

CONCLUSIONS

Our Mayo MGRS Prediction Tool is useful assisting clinicians in predicting the probability of finding an MGRS lesion in a kidney biopsy.

Monoclonal gammopathy of renal significance (MGRS): retrospective monocentric analysis of clinical outcomes and treatment strategies

Monoclonal Gammopathy of Renal Significance (MGRS) is a group of rare disorders in which monoclonal proteins cause kidney damage. Due to its rarity, ongoing research is vital to refine diagnostics, enhance treatment, and improve outcomes. This retrospective study analyzed 34 patients with renal biopsy-proven MGRS-defining lesions. Patients were divided into two subgroups: kidney-limited AL amyloidosis (MGRS-A, 44%, n = 15) and other MGRS (MGRS-NA, 56%, n = 19). Key outcomes included progression-free survival and overall survival. Baseline characteristics such as histopathology, plasma cell percentage, kidney function, and proteinuria were documented alongside initial treatments, and hematologic and renal response. Distinct differences were observed between the two groups: MGRS-NA was primarily associated with glomerular lesions, while MGRS-A exhibited broader kidney involvement. Treatment varied: bortezomib for plasma cell-driven cases and rituximab for B-cell-related conditions. Anemia was the most common side effect (71%), associated with treatment intensity. Despite similar overall survival outcomes, MGRS-A followed a more aggressive course, with a shorter time from diagnosis to death (206 vs. 728 days). Renal and hematologic responses were comparable between the groups, although baseline factors such as hemoglobin and CRP levels were predictive of mortality. These findings underscore the need for more precise characterization and standardized criteria to optimize the management of MGRS.

Clinical and Pathological Characteristics of Non-AL Amyloidosis MGRS: A Single-Center Experience Over 10 Years

Objective

Monoclonal gammopathy of renal significance (MGRS) is a heterogeneous and relatively recently defined disorder that encompasses many kidney and hematologic pathologies. MGRS remains a rare disease and there is a need for more literature regarding its treatment and outcomes. In this study, we share our center's experience with MGRS including incidence of different kidney pathologies, clone type, kidney and hematologic response, and progression-free survival.

Methods

Data from 35 patients diagnosed with MGRS excluding light-chain amyloidosis between 2013 and 2022 at a single Canadian tertiary care center were retrospectively analyzed. All cases required kidney biopsy. Initial treatment included regimens containing bortezomib, rituximab, or cyclosporine, or steroids only. Parameters studied included incidence of different kidney pathologies, clone type, depth of hematologic response, kidney survival (KS), overall survival (OS), and progression-free survival (PFS).

Results

Out of 35 patients, there were 10 cases of monoclonal immunoglobulin deposition disease, 8 of proliferative glomerulonephritis with immune deposits, 5 of microtubular immune deposits including immunotactoid and types 1 and 2 cryoglobulinemic nephropathy, 3 of C3 glomerulonephritis, and 9 of other diagnoses. There were 21 cases with a plasma cell clone identified in bone marrow, 2 each of B cell and low-grade lymphoma, 1 atypical T cell clone, and 9 cases without an expanded clone on bone marrow biopsy. A total of 6 patients required kidney replacement therapy and 4 patients died; the median PFS was 59.3 months. Very good partial hematologic response or better was significantly associated with decreased proteinuria but not preserved eGFR. There was a non-significant trend toward better PFS with hematologic response.

Conclusion

Our experience confirms that MGRS is a heterogeneous disease and adds to the literature concerning the diagnosis and treatment of MGRS. Successful treatment of the underlying hematologic disorder with targeted therapy is more likely to lead to an improvement in kidney function.

Genomic instability and genetic heterogeneity in aging: insights from clonal hematopoiesis (CHIP), monoclonal gammopathy (MGUS), and monoclonal B-cell lymphocytosis (MBL)

Aging is a multifaceted process characterized by a gradual decline in physiological function and increased susceptibility to a range of chronic diseases. Among the molecular and cellular mechanisms driving aging, genomic instability is a fundamental hallmark, contributing to increased mutation load and genetic heterogeneity within cellular populations. This review explores the role of genomic instability and genetic heterogeneity in aging in the hematopoietic system, with a particular focus on clonal hematopoiesis of indeterminate potential (CHIP), monoclonal gammopathy of undetermined significance (MGUS), and monoclonal B-cell lymphocytosis (MBL) as biomarkers. CHIP involves the clonal expansion of hematopoietic stem cells with somatic mutations. In contrast, MGUS is characterized by the presence of clonal plasma cells producing monoclonal immunoglobulins, while MBL is characterized by clonal proliferation of B cells. These conditions are prevalent in the aging population and serve as measurable indicators of underlying genomic instability. Studying these entities offers valuable insights into the mechanisms by which somatic mutations accumulate and drive clonal evolution in the hematopoietic system, providing a deeper understanding of how aging impacts cellular and tissue homeostasis. In summary, the hematopoietic system serves as a powerful model for investigating the interplay between genomic instability and aging. Incorporating age-related hematological conditions into aging research, alongside other biomarkers such as epigenetic clocks, can enhance the precision and predictive power of biological age assessments. These biomarkers provide a comprehensive view of the aging process, facilitating the early detection of age-related diseases and hopefully enabling personalized healthcare strategies.

Diagnosis and management of monoclonal gammopathy of renal significance: A British Society for Haematology good practice paper

This guideline provides consensus opinion on the investigations required for people presenting with suspected monoclonal gammopathy of renal significance to both nephrology and haematology physicians. The guideline discusses the principles of treating a patient with MGRS and provides recommendations for both supportive management and haematological therapy. It details the recommended on-going monitoring required for both specialty areas.

Minimal Residual Disease Significance in Multiple Myeloma Patients Treated with Anti-CD38 Monoclonal Antibodies

Minimal residual disease (MRD) evaluation is a recognized endpoint in clinical trials. Both next-generation flow and sequencing could be used as complementary techniques to detect myeloma cells after therapy to measure the depth of response and novel drug efficacy. Anti-CD38 monoclonal antibodies combined with proteasome inhibitors and immunomodulatory drugs have increased the quality of response in myeloma patients, and MRD evaluation is also entering routine clinical practice in many hematological centers. This review analyzes updated results from recent clinical trials utilizing anti-CD38 monoclonal antibodies such as isatuximab and daratumumab in terms of their responses and MRD data. MRD-driven therapy appears promising for the future of MM patients, and emerging minimally invasive techniques to assess MRD are under investigation as novel potential methods to replace or integrate traditional MRD evaluation.

Clinical Presentation and Long-Term Survival Outcomes of Patients With Monoclonal Gammopathy of Renal Significance (MGRS): A Multicenter Retrospective Study

INTRODUCTION

MGRS are new rare clinical entities, whose recognition and optimal management is evolving.

METHODS

To implement real-life data, we retrospectively analysed a multicentre cohort of 60 patients with renal biopsy-proven MGRS receiving mainly novel treatments (between 2006 and 2021) in eight Italian centres. Based on renal biopsy, patients were divided into two subgroups: AL amyloidosis (70%, n = 42) and other-MGRS (30%, n = 18).

RESULTS

Baseline characteristics follow typical manifestations of MGRS disorders in terms of small clonal burden, laboratory and clinical features. More patients with AL amyloidosis had monotypic lambda light-chain disease, estimated glomerular filtration rate (eGFR) ≥ 60 mL/min and nephrotic proteinuria than other-MGRS group. The most widely used drug was bortezomib, and about one-third of patients underwent ASCT. Overall response rate was 86% with no differences in the two subgroups. However, high-quality hematologic responses ≥very good partial response (VGPR) were greater in AL amyloidosis than in other-MGRS group (67% vs 28%, p = 0.015). The depth of haematological response influenced renal response, obtained in 32 (59%) of evaluable patients, similarly in the subgroups. Indeed, 75% patients with ≥ VGPR (p = 0.049) and none with stable disease (p ≤ 0.001) obtained a renal response. No association between renal response and histotypes (p = 0.9) or type of first-line therapy (p = 0.3) was found. At a median follow-up of 54.4 months (IQR 24.8-102.8), median progression-free survival (PFS) was 100.1 months (95% CI 34.9-NR), and median overall survival not reached (95% CI 129.8-NR). No significant difference emerged between the two groups in terms of survival outcomes. Achieving ≥ VGPR was confirmed as the main independent predictor of prolonged PFS in the general population (HR = 0.29, p = 0.023) and AL amyloidosis group (HR 0.23; p = 0.023). Preserved renal function at diagnosis was predictive of improved PFS in the AL amyloidosis group (eGFR ≥ 60 mL/min: HR = 0.003; p = 0.018; eGFR 30-60 mL/min: HR = 0.04, p = 0.046).

CONCLUSION

Further research is warranted to develop standardised response criteria and treatment strategies to improve MGRS management.

Unraveling monoclonal gammopathy of renal significance: a mini review on kidney complications and clinical insights

Monoclonal gammopathy of renal significance (MGRS) is where kidney injury occurs due to the accumulation or effects of abnormal monoclonal proteins. These proteins, originating from non-cancerous or pre-cancerous plasma cells or B cells, deposit in specific areas of the kidney. Mechanisms contributing to MGRS include high levels of vascular endothelial growth factor secretion, autoantibodies targeting complement components, and targeting specific receptors leading to nephropathy. Kidney lesions in monoclonal gammopathy of renal significance (MGRS) are classified based on the presence of organized or nonorganized deposits, including fibrillar, microtubular, or crystal inclusions. Kidney biopsy is essential for confirming the diagnosis of MGRS by identifying monoclonal immunoglobulin deposits. Immunofluorescence helps determine the class of light and/or heavy chain involved in MGRS. The treatment approach is clone-directed and hence it depends on the presence of B cell clone or plasma cell clone or any detectable monoclonal protein. Chemotherapy targeting plasma cell or B cell malignancies and autologous hematopoietic cell transplantation may be used to manage MGRS. Kidney outcomes in MGRS patients strongly correlate with the hematologic response to chemotherapy.

Monoclonal gammopathy of renal significance from the perspective of nephrologists

Kidney disease is a frequent complication of multiple myeloma and other malignancies associated with monoclonal gammopathies. Additionally, dysproteinemia-related kidney disease can occur independently of overt multiple myeloma or hematologic malignancies. Monoclonal gammopathy of renal significance (MGRS) is a spectrum of disorders in which a monoclonal immunoglobulin produced by a benign or premalignant B-cell or plasma cell clone causes kidney damage. MGRS-associated renal disease manifests in various forms, including immunoglobulin-associated amyloidosis, monoclonal immunoglobulin deposition diseases (light chain, heavy chain, and combined light and heavy chain deposition diseases), proliferative glomerulonephritis with monoclonal immunoglobulin deposits, C3 glomerulopathy with monoclonal gammopathy, and light chain proximal tubulopathy. Although MGRS is a nonmalignant or premalignant hematologic condition, it has significant renal implications that often lead to progressive kidney damage and, eventually, end-stage kidney disease. This review discusses the epidemiology, pathogenesis, and management of MGRS and focuses on the perspective of nephrologists.

The Role of Monoclonal Antibodies in the Treatment of Myeloma Kidney Disease

Renal failure is one of the most important manifestations of multiple myeloma. It is caused by renal lesions such as cast nephropathy, immunoglobulin deposition disease, AL amyloidosis or other glomerular and/or tubular diseases, mostly due to the toxic effect of free light chains in serum. Renal failure can represent a clinical emergency and is associated with poor outcome in newly diagnosed and relapsed/refractory multiple myeloma patients. Although progression-free survival and overall survival have improved with the introduction of novel agents, renal failure remains a challenge for the treatment of patients with multiple myeloma. Monoclonal antibodies are a component of therapy for newly diagnosed and relapsed/refractory patients and, based on clinical trials and real-world experience, are also safe and effective for subjects with renal failure, even if they are on dialysis. Most of the data are on anti-CD38 and anti-SLAM7 antibodies, but new antibody-drug conjugates such as belantamab mafodotin and bispecific antibodies also appear to be effective in myeloma kidney disease. In the future, we will have to face some challenges, such as defining new criteria for renal response to treatment, defining specific trials for these difficult-to-treat patients and integrating different therapeutic options.

Paraprotein-Mediated Glomerular Diseases

Paraproteinemias are a group of complex diseases associated with an overproduction of a monoclonal immunoglobulin that can cause a diversity of kidney disorders and end-organ damage. In this review, we focus on paraprotein-mediated glomerular diseases. Kidney biopsy plays a crucial role in diagnosing these disorders, enabling the identification of specific histological patterns. These lesions are categorized into organized (such as amyloidosis, immunotactoid glomerulopathy, fibrillary glomerulonephritis, cryoglobulinemic glomerulonephritis, and monoclonal crystalline glomerulopathies) and nonorganized deposits (such as monoclonal Ig deposition disease and proliferative glomerulonephritis with monoclonal Ig deposits) based on the characteristics of immunofluorescence findings and the ultrastructural appearance of deposits on electron microscopy. This review aims to provide an update, highlight, and discuss clinicopathological aspects such as definition, epidemiology, clinical manifestations, mechanisms of kidney injury, histological features, and diagnostic procedures.

Monoclonal Gammopathy and Its Association with Progression to Kidney Failure and Mortality in Patients with CKD

BACKGROUND

Little is known about the prognostic significance of monoclonal gammopathy of undetermined and renal significance (MGUS and MGRS) in patients with CKD. The objective of this study was to determine the clinical and kidney outcomes of patients with CKD with either MGUS or MGRS compared with those with CKD without MGUS or MGRS.

METHODS

We conducted a retrospective cohort study from 2013 to 2018. Patients who had both CKD diagnosis and monoclonal testing were identified. Patients were divided into MGRS, MGUS, and no monoclonal gammopathy groups. Cumulative incidence functions and Cox proportional hazards regression were used to model time to event data and to evaluate the association between monoclonal gammopathy status and risk of kidney failure, with death treated as a competing risk.

RESULTS

Among 1535 patients, 59 (4%) had MGRS, 648 (42%) had MGUS, and 828 (54%) had no monoclonal gammopathy. Unadjusted analysis showed that compared with no monoclonal gammopathy patients, patients with MGRS were at higher risk of kidney failure (hazard ratio [HR] [95% confidence interval]: 2.5 [1.5 to 4.2] but not patients with MGUS (HR [95% confidence interval]: 1.3 [0.97 to 1.6]), after taking death into account as a competing risk. However, in the multivariable analysis, after adjusting for age, sex, eGFR, proteinuria, and Charlson Comorbidity Index, the risk of progression to kidney failure (with death as competing risk) in the MGRS group was no longer statistically significant (HR: 0.9 [0.5 to 1.8]). The same was also true for the MGUS group compared with the group with no monoclonal gammopathy (HR: 1.3 [0.95 to 1.6]). When evaluating the association between MGUS/MGRS status and overall survival, MGRS was significantly associated with mortality in fully adjusted models compared with the group with no monoclonal gammopathy, while MGUS was not.

CONCLUSIONS

After adjusting for traditional risk factors, MGUS/MGRS status was not associated with a greater risk of kidney failure, but MGRS was associated with a higher risk of mortality compared with patients with no monoclonal gammopathy.

Systematic review and meta-analysis of the clinical features of MGRS

BACKGROUND

It is crucial to identify patients with monoclonal gammopathy of renal significance (MGRS) from those without MGRS but with monoclonal gammopathy and concomitant kidney diseases. However, there have been few studies with large sample sizes, and their findings were inconsistent. This study aimed to conduct a meta-analysis of MGRS to describe the general characteristics of MGRS and its predictive factors.

METHODS

Cohort or case-control studies published through December 2022 and related to clinicopathological features of MGRS were retrieved from the PubMed, Cochrane Library, Web of Science, Scopus, and Embase databases. Two researchers searched for studies that met the inclusion criteria. In the univariate analysis, fixed- or random- effects models were used to obtain pooled estimates of the weighted mean difference (WMD) and odds ratio (OR) for risk factors. In the multivariate analysis, the ORs of the independent risk factors from each study were pooled after transforming the original estimates.

RESULTS

The meta-analysis included six studies. Univariate analysis showed that the following variables were statistically significant in MGRS: age (WMD = 1.78, 95%CI 0.21-3.35), hypertension (OR = 0.54, 95%CI 0.4-0.73), diabetes (OR = 0.42, 95%CI 0.29-0.59), albumin (WMD = - 0.26, 95%CI - 0.38--0.14), urinary protein level (WMD = 0.76, 95%CI 0.31-1.2), urinary protein ≥ 1.5 g/d (OR = 1.98, 95%CI 1.46-2.68), lambda-chain value (WMD = 29.02, 95%CI 16.55-41.49), abnormal free light-chain ratio (OR = 4.16, 95%CI 1.65-10.47), bone marrow puncture rate (OR = 5.11, 95% CI 1.31-19.95), and abnormal bone marrow outcome rate (OR = 9.63, 95%CI 1.98-46.88). Multivariate analysis showed urinary protein ≥ 1.5 g/d (OR = 2.80, 95%CI 1.53-5.15) and an abnormal free light-chain ratio (OR = 6.98, 95%CI 4.10-11.91) were associated with predictors of MGRS.

CONCLUSIONS

Compared with non-MGRS patients with monoclonal gammopathy and concomitant kidney diseases, patients with MGRS were older, had fewer underlying diseases, more urinary protein, more abnormal free light-chain ratio, and more abnormal bone marrow results. Urinary protein ≥ 1.5 g/d and an abnormal free light-chain ratio were independent risk factors for MGRS.

Monoclonal Gammopathy of Undetermined Cardiovascular Significance; Current Evidence and Novel Insights

Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant condition characterized by the presence of low levels of a monoclonal protein in the serum and a low percentage of clonal plasma cells in the bone marrow. MGUS may progress to multiple myeloma or other plasma cell disorders at a rate of 1% annually. However, MGUS may also have adverse effects on the cardiovascular system independent of its malignant potential. Emerging data have shown that MGUS is associated with cardiovascular disease. The mechanisms underlying this association are not fully understood but may involve genetic abnormalities, vascular calcification, cryoglobulinemia, cold agglutinin disease, autoantibodies and the direct or indirect effects of the monoclonal protein on the vascular endothelium. Herein, we review current evidence in this field and we suggest that patients with MGUS may benefit from regular cardiovascular risk assessment to prevent severe cardiovascular complications, in parallel with close hematological follow-up to monitor potential disease progression.

Clinical Outcomes of Monoclonal Gammopathy of Renal Significance Without Detectable Clones

Introduction

Monoclonal gammopathy of renal significance (MGRS) is characterized by monoclonal immunoglobulin deposition in kidneys. However, monoclonal immunoglobulin and responsible clone(s) are not always detectable. Treatment response and kidney outcome of MGRS without detectable clones remain unclear.

Methods

In this single-center, retrospective cohort study, we identified MGRS without detectable clones from our biopsy repository between 2010 and 2022. We investigated the correlations between treatment regimens and kidney outcomes defined by proteinuria and estimated glomerular filtration rate (eGFR), and the impact of repeat kidney biopsy.

Results

Our study cohort included 29 cases (27 native kidney and 2 transplant allograft biopsies) of MGRS without detectable clones. At diagnosis, median serum creatinine was 1.8 mg/dl (interquartile range [IQR] 1.3-2.7), with proteinuria 4.6 g/gCr (IQR 2.3-7.9). Treatment regimens were variable: 6 (21%) received conservative therapy, 13 (45%) received plasma cell clone-directed therapy, 8 (28%) received lymphocytic clone-directed therapy, and 2 (7%) received nonclone-directed immunosuppressive therapy. Of 24 patients with proteinuria >0.5 g/gCr at diagnosis, 9 (38%) and 6 (25%) achieved complete response (CR) and partial response (PR), respectively. If interstitial fibrosis and tubular atrophy (IFTA) was >50% at the initial biopsy, less proportion of patients achieved CR. Six of 7 repeat biopsies showed progression of chronic changes (e.g., IFTA) but provided limited information on treatment response.

Conclusion

Treatment regimens and outcomes of MGRS without detectable clones were extremely variable. Repeat biopsy provided limited information to assess disease activity or the need for additional treatment. More sensitive tools are needed to detect clones and to assess treatment response.

Role of the mechanisms for antibody repertoire diversification in monoclonal light chain deposition disorders: when a friend becomes foe

The adaptive immune system of jawed vertebrates generates a highly diverse repertoire of antibodies to meet the antigenic challenges of a constantly evolving biological ecosystem. Most of the diversity is generated by two mechanisms: V(D)J gene recombination and somatic hypermutation (SHM). SHM introduces changes in the variable domain of antibodies, mostly in the regions that form the paratope, yielding antibodies with higher antigen binding affinity. However, antigen recognition is only possible if the antibody folds into a stable functional conformation. Therefore, a key force determining the survival of B cell clones undergoing somatic hypermutation is the ability of the mutated heavy and light chains to efficiently fold and assemble into a functional antibody. The antibody is the structural context where the selection of the somatic mutations occurs, and where both the heavy and light chains benefit from protective mechanisms that counteract the potentially deleterious impact of the changes. However, in patients with monoclonal gammopathies, the proliferating plasma cell clone may overproduce the light chain, which is then secreted into the bloodstream. This places the light chain out of the protective context provided by the quaternary structure of the antibody, increasing the risk of misfolding and aggregation due to destabilizing somatic mutations. Light chain-derived (AL) amyloidosis, light chain deposition disease (LCDD), Fanconi syndrome, and myeloma (cast) nephropathy are a diverse group of diseases derived from the pathologic aggregation of light chains, in which somatic mutations are recognized to play a role. In this review, we address the mechanisms by which somatic mutations promote the misfolding and pathological aggregation of the light chains, with an emphasis on AL amyloidosis. We also analyze the contribution of the variable domain (V_L) gene segments and somatic mutations on light chain cytotoxicity, organ tropism, and structure of the AL fibrils. Finally, we analyze the most recent advances in the development of computational algorithms to predict the role of somatic mutations in the cardiotoxicity of amyloidogenic light chains and discuss the challenges and perspectives that this approach faces.

Management of multiple myeloma-related renal impairment: recommendations from the International Myeloma Working Group

Here, the International Myeloma Working Group (IMWG) updates its clinical practice recommendations for the management of multiple myeloma-related renal impairment on the basis of data published until Dec 31, 2022. All patients with multiple myeloma and renal impairment should have serum creatinine, estimated glomerular filtration rate, and free light chains (FLCs) measurements together with 24-h urine total protein, electrophoresis, and immunofixation. If non-selective proteinuria (mainly albuminuria) or involved serum FLCs value less than 500 mg/L is detected, then a renal biopsy is needed. The IMWG criteria for the definition of renal response should be used. Supportive care and high-dose dexamethasone are required for all patients with myeloma-induced renal impairment. Mechanical approaches do not increase overall survival. Bortezomib-based regimens are the cornerstone of the management of patients with multiple myeloma and renal impairment at diagnosis. New quadruplet and triplet combinations, including proteasome inhibitors, immunomodulatory drugs, and anti-CD38 monoclonal antibodies, improve renal and survival outcomes in both newly diagnosed patients and those with relapsed or refractory disease. Conjugated antibodies, chimeric antigen receptor T-cells, and T-cell engagers are well tolerated and effective in patients with moderate renal impairment.

Glomerulonephritis: immunopathogenesis and immunotherapy

'Glomerulonephritis' (GN) is a term used to describe a group of heterogeneous immune-mediated disorders characterized by inflammation of the filtration units of the kidney (the glomeruli). These disorders are currently classified largely on the basis of histopathological lesion patterns, but these patterns do not align well with their diverse pathological mechanisms and hence do not inform optimal therapy. Instead, we propose grouping GN disorders into five categories according to their immunopathogenesis: infection-related GN, autoimmune GN, alloimmune GN, autoinflammatory GN and monoclonal gammopathy-related GN. This categorization can inform the appropriate treatment; for example, infection control for infection-related GN, suppression of adaptive immunity for autoimmune GN and alloimmune GN, inhibition of single cytokines or complement factors for autoinflammatory GN arising from inborn errors in innate immunity, and plasma cell clone-directed or B cell clone-directed therapy for monoclonal gammopathies. Here we present the immunopathogenesis of GN and immunotherapies in use and in development and discuss how an immunopathogenesis-based GN classification can focus research, and improve patient management and teaching.

Functional Imaging in the Evaluation of Treatment Response in Multiple Myeloma: The Role of PET-CT and MRI

Bone disease is among the defining characteristics of symptomatic Multiple Myeloma (MM). Imaging techniques such as fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET/CT) and magnetic resonance imaging (MRI) can identify plasma cell proliferation and quantify disease activity. This function renders these imaging tools as suitable not only for diagnosis, but also for the assessment of bone disease after treatment of MM patients. The aim of this article is to review FDG PET/CT and MRI and their applications, with a focus on their role in treatment response evaluation. MRI emerges as the technique with the highest sensitivity in lesions' detection and PET/CT as the technique with a major impact on prognosis. Their comparison yields different results concerning the best tool to evaluate treatment response. The inhomogeneity of the data suggests the need to address limitations related to these tools with the employment of new techniques and the potential for a complementary use of both PET/CT and MRI to refine the sensitivity and achieve the standards for minimal residual disease (MRD) evaluation.

Monoclonal Gammopathies of Clinical Significance: A Critical Appraisal

Monoclonal gammopathies of clinical significance (MGCSs) represent a group of diseases featuring the association of a nonmalignant B cells or plasma cells clone, the production of an M-protein, and singularly, the existence of organ damage. They present a current framework that is difficult to approach from a practical clinical perspective. Several points should be addressed in order to move further toward a better understanding. Overall, these entities are only partially included in the international classifications of diseases. Its definition and classification remain ambiguous. Remarkably, its real incidence is unknown, provided that a diagnostic biopsy is mandatory in most cases. In fact, amyloidosis AL is the final diagnosis in a large percentage of patients with renal significance. On the other hand, many of these young entities are syndromes that are based on a dynamic set of diagnostic criteria, challenging a timely diagnosis. Moreover, a specific risk score for progression is lacking. Despite the key role of the clinical laboratory in the diagnosis and prognosis of these patients, information about laboratory biomarkers is limited. Besides, the evidence accumulated for many of these entities is scarce. Hence, national and international registries are stimulated. In particular, IgM MGCS deserves special attention. Until now, therapy is far from being standardized, and it should be planned on a risk and patient-adapted basis. Finally, a comprehensive and coordinated multidisciplinary approach is needed, and specific clinical trials are encouraged.

Steps towards a Multiple Myeloma Cure?

Multiple myeloma survival has increased in last 20 years because of new treatments, better clinical management due to novel diagnostic tools such as imaging, and better understanding of the disease, biologically and genetically. Novel drugs have been introduced that act with different therapeutic mechanisms, but so have novel therapeutic strategies such as consolidation and maintenance after autologous stem cell transplant. Imaging (such as PET-CT and MRI) has been applied at diagnosis and after therapy for minimal residual disease monitoring. Multiparametric flow and molecular NGS may detect, with high-sensitivity, residual monoclonal plasma cells in the bone marrow. With this novel therapeutic and biological approach, a considerable fraction of multiple myeloma patients can achieve durable remission or even MGUS-like regression, which can ultimately lead to disease disappearance. The big dogma, “Myeloma is an incurable disease”, is hopefully fading.