A randomized trial of cyclosporine in patients with steroid-resistant focal segmental glomerulosclerosis. North America Nephrotic Syndrome Study Group

Focal Segmental Glomerulosclerosis

Focal segmental glomerular sclerosis (FSGS) is a histological lesion characterized by sclerosis in sections (segmental) of some glomeruli (focal) in association with podocyte injury. Historically, FSGS has often been characterized as a disease, but it is a heterogeneous entity based on etiology, clinical course, and therapeutic approach. A unifying feature is podocyte injury and loss, which can be primary or the result of secondary maladaptive responses to glomerular stressors. FSGS has been demonstrated over time to carry a large health burden and remains a leading glomerular cause of ESRD globally. Recent clinical practice guidelines highlight the unmet scientific need for better understanding of disease pathogenesis, particularly for immunologic etiologies, as well as more targeted therapeutic drug development. In this review, we will discuss the current FSGS classification scheme, pathophysiologic mechanisms of injury, and treatment guidelines, along with emerging and investigational therapeutics.

Membranous nephropathy treatment standard

Membranous nephropathy (MN) is characterized by deposition of immune complexes leading to thickening of glomerular basement membranes. Over time, the understanding of MN has evolved, with the identification of specific autoantibodies against novel podocyte antigens and the unraveling of intricate pathogenic pathways. Although the anti-CD20 monoclonal antibody rituximab is favored as part of the initial therapy in MN, a subgroup of MN patients may be resistant to rituximab necessitating the use of alternative agents such as cytotoxic therapies. In addition, newer agents such as novel anti-CD20 monoclonal antibodies, therapies targeting the CD38-positive plasma cells and anti-complement therapy are being studied in patients who are resistant to traditional treatment strategies. This manuscript furnishes a review of the novel developments in the pathophysiology of MN including the identification of target antigens and current treatment standards for MN, concentrating on evidenced-based interventions designed to attain remission and to prevent disease progression.

Focal Segmental Glomerulosclerosis: Assessing the Risk of Relapse

Introduction

Kidney outcomes are improved in primary focal segmental glomerulosclerosis (FSGS) by maintaining a remission in proteinuria. However, characteristics associated with relapses are uncertain. We sought to identify these by analyzing each remission.

Methods

We performed a retrospective study in patients with biopsy-proven lesions of FSGS, absent identifiable secondary cause, who had at least 1 remission from nephrotic-range proteinuria. In each patient, we identified every remission, every relapse, and their durations. Using a multilevel logistic regression to account for the clustering of multiple remissions within a patient, we tested which clinical characteristics were independently associated with relapses.

Results

In 203 individuals, 312 remissions occurred, 177 with and 135 without relapse. A minority of remissions were atypical, defined by either absent hypoalbuminemia and/or no immunosuppression (IS), in contrast to the classic nephrotic syndrome that remits with IS. Atypical remission variants were just as likely to relapse as the classical presentation. Only 24% of remission events were on maintenance therapy at relapse. Independent characteristics associated with relapses were higher maximal proteinuria while nephrotic; and in remission, higher nadir proteinuria, lower serum albumin, and higher blood pressure. Using these variables, we created a tool estimating the 1-year risk of relapse ranging from 9% to 80%, well-calibrated to the observed data.

Conclusion

In FSGS, relapses are frequent but predictable using independent clinical characteristics. We also provide evidence that atypical presentations remit and relapse following the same pattern as classic FSGS presentations. Treatment strategies to prolong remission duration should be addressed in future trials.

Current understanding of the molecular mechanisms of circulating permeability factor in focal segmental glomerulosclerosis

The pathogenetic mechanisms underlying the onset and the post-transplant recurrence of primary focal segmental glomerulosclerosis (FSGS) are complex and remain yet to be fully elucidated. However, a growing body of evidence emphasizes the pivotal role of the immune system in both initiating and perpetuating the disease. Extensive investigations, encompassing both experimental models and patient studies, have implicated T cells, B cells, and complement as crucial actors in the pathogenesis of primary FSGS, with various molecules being proposed as potential "circulating factors" contributing to the disease and its recurrence post kidney-transplantation. In this review, we critically assessed the existing literature to identify essential pathways for a comprehensive characterization of the pathogenesis of FSGS. Recent discoveries have shed further light on the intricate interplay between these mechanisms. We present an overview of the current understanding of the engagement of distinct molecules and immune cells in FSGS pathogenesis while highlighting critical knowledge gaps that require attention. A thorough characterization of these intricate immune mechanisms holds the potential to identify noninvasive biomarkers that can accurately identify patients at high risk of post-transplant recurrence. Such knowledge can pave the way for the development of targeted and personalized therapeutic approaches in the management of FSGS.

Curcumin ameliorates focal segmental glomerulosclerosis by inhibiting apoptosis and oxidative stress in podocytes

Focal segmental glomerulosclerosis (FSGS), a podocyte disease, is the leading cause of end-stage renal disease (ESRD). Nevertheless, the current effective treatment for FSGS is deficient. Curcumin (CUR) is a principal curcuminoid of turmeric, which is a member of the ginger family. Previous studies have shown that CUR has renoprotective effects. However, the mechanism of CUR in anti-FSGS is not clear. This study aimed to explore the mechanism of CUR against FSGS through a combination of network pharmacological methods and verification of experiments. The analysis identified 98 shared targets of CUR against FSGS, and these 98 targets formed a network of protein-protein interactions (PPI). Of these 98 targets, AKT1, TNF, IL-6, VEGFA, STAT3, MAPK3, HIF1A, CASP3, IL1B, and JUN were identified as the hub targets. Molecular docking suggested that the best binding to CUR is MAPK3 and AKT1. Apoptotic process and cell proliferation were identified as the main biological processes of CUR against FSGS by gene ontology (GO) analysis. The most enriched signaling pathway in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was the PI3K-AKT signaling pathway. Western blots and flow cytometry showed that CUR could inhibit adriamycin (ADR) induced apoptosis, oxidative stress damage, and attenuate podocyte epithelial-mesenchymal transition (EMT) by repressing the AKT signaling pathway. Collectively, our study demonstrates that CUR can attenuate apoptosis, oxidative stress damage, and EMT in FSGS in vitro. These results supply a compelling basis for future studies of CUR for the clinical treatment of FSGS.

Japanese clinical practice patterns of primary nephrotic syndrome 2021: a web-based questionnaire survey of certified nephrologists

BACKGROUND

With the publication of the "Evidence-Based Clinical Practice Guideline for Nephrotic Syndrome 2020," we examined nephrologists' adherence to the recommendations of four of its clinical questions (CQs).

METHODS

This was a cross-sectional web-based survey conducted between November and December 2021. The target population comprised nephrologists certified by the Japanese Society of Nephrology who were recruited using convenience sampling. The participants answered six items regarding the four CQs about adult patients with nephrotic syndrome and their characteristics.

RESULTS

In total, 434 respondents worked in at least 306 facilities, of whom 386 (88.9%) provided outpatient care for primary nephrotic syndrome. Of these patients, 179 (41.2%) answered that they would not measure anti- phospholipase A2 receptor antibody levels in cases of suspected primary membranous nephropathy (MN) in which kidney biopsy was not possible (CQ1). Regarding immunosuppressants as maintenance therapy after relapse of minimal change nephrotic syndrome (CQ2), cyclosporine was the most common choice (290 [72.5%] and 300 [75.0%] of 400 respondents after the first and second relapses, respectively). The most common treatment for steroid-resistant cases of primary focal segmental glomerulosclerosis (CQ3) was cyclosporine (323 of 387, 83.5%). For the initial treatment of primary MN with nephrotic-range proteinuria (CQ4), corticosteroid monotherapy was the most common choice (240 of 403, 59.6%), followed by corticosteroid and cyclosporine (114, 28.3%).

CONCLUSION

Gaps in recommendations and practices regarding serodiagnosis and treatment of MN (i.e., CQ1 and 4) are observed, suggesting the need to address the barriers to their insurance reimbursement and the lack of evidence behind them.

[Diagnosis and treatment of focal-segmental glomerulosclerosis-2023]

The histopathological term focal-segmental glomerulosclerosis comprises different pathogenic processes with the unifying features of a high proteinuria and the name-giving glomerular lesion pattern seen on light microscopy. A differentiation according to the underlying cause into primary, secondary and genetic forms is therefore of utmost importance. The pathogenesis of primary focal-segmental glomerulosclerosis remains unknown but, like minimal-change disease, an autoimmune-mediated process leading to podocyte damage is assumed. Consequently, the unifying term "podocytopathy" is increasingly being used for both entities. Supportive treatment measures to preserve kidney function are important in all subtypes. In contrast, immunosuppressive treatment is only indicated in primary focal-segmental glomerulosclerosis. Steroid-dependence, steroid-resistance and frequently relapsing disease often complicate disease management and necessitate alternative treatment strategies. Here, the Austrian Society of Nephrology (ÖGN) provides consensus recommendations on how to best diagnose and manage patients with focal-segmental glomerulosclerosis.

Role of cyclosporin A in the treatment of kidney disease and nephrotoxicity

The clinical use of cyclosporin A (CsA) has led to significant advances and achievements in the field of transplantation and immune diseases. However, the nephrotoxicity of CsA is a major concern in current immunosuppression regimens. CsA causes abnormal kidney function while treating kidney disease, causing problems for clinicians and patients. Evidence of CsA nephrotoxicity is almost always present in transplant recipients after long-term CsA administration (up to 10 years), and similar phenomena occur with other calcineurin inhibitors. In this review, we summarize the mechanisms and influencing factors of CsA for the treatment of primary nephrotic syndrome. The mechanisms of CsA nephrotoxicity, clinical-pathological features, diagnosis, prevention strategies, and risk factors are summarized. We discuss the correlates and mechanisms of the switch between kidney disease prevention and nephrotoxicity of CsA to better understand the function of CsA in the kidney and to provide a basis for the prevention and treatment of CsA nephrotoxicity.

Quantifying the benefits of remission duration in focal and segmental glomerulosclerosis

BACKGROUND

Although the clinical benefit of obtaining a remission in proteinuria in nephrotic patients with focal and segmental glomerulosclerosis (FSGS) is recognized, the long-term value of maintaining it and the impact of relapses on outcome are not well described.

METHODS

We examined the impact of remissions and relapses on either a 50% decline in kidney function or ESKD (combined event) using time-dependent and landmark analyses in a retrospective study of all patients from the Toronto Glomerulonephritis Registry with biopsy-proven FSGS, established nephrotic-range proteinuria and at least one remission.

RESULTS

In the 203 FSGS individuals with a remission, 89 never relapsed and 114 experienced at least one relapse. The first recurrence was often followed by a repeating pattern of remission and relapse. The 10-year survival from a combined event was 15% higher in those with no relapse versus those with any relapse. This smaller than anticipated difference was related to the favorable outcome in individuals whose relapses quickly remitted. Relapsers who ultimately ended in remission (n = 46) versus in relapse (n = 68) experienced a 91% and 32% 7-year event survival (p<0.001). Using time-varying survival analyses that considered all periods of remission and relapse in every patient and adjusting for each period's initial eGFR, the state of relapse was associated with a 2.17 (95%CI,1.32-3.58, p = 0.002) greater risk of experiencing a combined event even in this FSGS remission cohort.

CONCLUSIONS

In FSGS, unless remissions are maintained and relapses avoided, long-term renal survival remains poor. Treatment strategies addressing remission duration remain poorly defined and should be an essential question in future trials.

Efficacy and Safety of Immunosuppressive Therapy in Primary Focal Segmental Glomerulosclerosis: A Systematic Review and Meta-analysis

Rationale & Objective

Focal segmental glomerulosclerosis (FSGS) is a rare condition that can lead to kidney function decline and chronic kidney failure. Immunosuppressants are used to treat primary FSGS. However, their efficacy and safety in FSGS are not clearly established. We assessed current knowledge on clinical effectiveness and safety of immunosuppressants for primary FSGS.

Study Design

Systematic review of randomized controlled trials, interventional nonrandomized controlled trials, observational studies, retrospective studies, and registries.

Setting & Participants

Patients with primary and genetic FSGS.

Selection Criteria for Studies

Medline, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for English-language, primary-FSGS studies from inception to 2019. Clinical outcomes were changes from baseline in proteinuria, kidney function, and kidney survival.

Data Extraction

2 investigators independently screened studies and extracted data.

Analytical Approach

Study results were summarized using random-effects models either as ratios of means between follow-up and baseline measurements or as HRs.

Results

We included 98 articles. Substantial heterogeneity was observed in patient baseline characteristics and study designs. Most studies assessed treatment with corticosteroids alone or combined with other drugs, mainly immunosuppressants. Patients treated with immunosuppressants showed reduced proteinuria (14 studies; ratio of means, 0.36; 95% CI, 0.20-0.47), decreased creatinine clearance (mean difference, −25.03; 95% CI, −59.33 to −9.27) and (significantly) lower estimated glomerular filtration rates (mean difference, −7.61 mL/min/1.73 m²; 95% CI, −14.98 to 0.25 mL/min/1.73 m²). Immunosuppressant therapy had an uncertain effect on reducing the chronic kidney failure risk. Hypertension and infections were the most commonly reported adverse events.

Limitations

Heterogeneity in study designs, patient populations, and treatment regimens; no access to individual patient–level data.

Conclusions

This systematic review supports proteinuria reduction with immunosuppressant therapy in primary FSGS over varying follow-up periods. The effects of immunosuppressants on kidney survival remain uncertain. This review underscores the need for better-designed and adequately controlled studies to assess immunosuppressant therapy in patients with primary FSGS.

The Role of Rituximab in Primary Focal Segmental Glomerular Sclerosis of the Adult

Introduction

Primary focal segmental glomerular sclerosis (FSGS) is a rare, likely immune-mediated disease. Rituximab (RTX) may play a role in management, although data in adults are scanty.

Methods

We collected cases of RTX-treated primary FSGS within the Italian Society of Nephrology Immunopathology Working Group and explored response rate (24-hour proteinuria <3.5 g and <50% compared with baseline, stable estimated glomerular filtration rate).

Results

A total of 31 patients were followed for at least 12 months; further follow-up (median 17 months, interquartile range [IQR] 15–33.5) was available for 11. At first RTX administration, median creatinine and 24-hour proteinuria were 1.17 mg/dl (IQR 0.83–1.62) and 5.2 g (IQR 3.3–8.81), respectively. Response rate at 3, 6, and 12 months was 39%, 52%, and 42%, respectively. In the first 12 months, creatinine level remained stable whereas proteinuria and serum albumin level improved, with an increase in the proportion of patients tapering other immunosuppressants. There were 6 patients who were retreated with RTX within 12 months, either for proteinuria increase or refractory disease; only the 2 responders to the first RTX course experienced a further response. At univariate analysis, 6-month response was more frequent in steroid-dependent patients (odds ratio [OR] 7.7 [95% CI 1.16–52.17]) and those with proteinuria <5 g/24 h (OR 8.25 [1.45–46.86]). During long-term follow-up, 4 of 5 responders at 12 months maintained a sustained response, either without further immunosuppression (2 of 4) or with pre-emptive RTX (2 of 4); 1 relapsed and responded to RTX retreatment.

Conclusion

RTX may be an option in primary FSGS, especially in steroid-dependent patients, with 24-hour proteinuria <5 g and previously responders to RTX. Optimal long-term management for responders is unclear, with some patients experiencing sustained remission and others requiring RTX retreatment, either preemptive or after rising proteinuria.

Histopathological and Clinical Findings of Biopsy-Proven Focal and Segmental Glomerulosclerosis: A Retrospective Study

Background

Focal segmental glomerulosclerosis (FSGS) is characterized by the presence of glomerular damage on histopathological examination. The major defining symptom of FSGS is proteinuria, which indicates damage to the glomerular filtration barrier. Additionally, FSGS is the most common cause of primary nephrotic syndrome. However, in Saudi Arabia, there is a paucity of research on this topic. Therefore, this study was designed to examine the clinical features, laboratory findings, and presence of comorbidities in patients with FSGS to determine their effects on clinical outcomes.

Methods

We retrospectively analyzed the histopathological and clinical data of patients diagnosed with FSGS via biopsy at King Abdulaziz University Hospital, Jeddah, Saudi Arabia, during the period 1989-2020. Biopsy samples were labeled according to the Columbia classification as tip, perihilar, cellular, collapsing, or not otherwise specified (NOS).

Results

We included 39 children and 21 adults. Males accounted for 54.1% of the sample. Hypertension was the most common comorbidity. Regarding FSGS subtypes, 60.9% of the lesions in the adult patients were collapsing lesions, followed by NOS (26.1%). In pediatric patients, 36.8% of the lesions were NOS, followed by collapsing lesions (28.9%). We also observed a very low rate of remission. In both age groups, the most common clinical presentation was nephrotic syndrome.

Conclusion

We found a high prevalence of collapsing and NOS FSGS subtypes in both the adult and pediatric age groups. The most prevalent outcome was the persistence of nephrotic syndrome with low rates of remission.

Interventions for focal segmental glomerulosclerosis in adults

BACKGROUND

Focal segmental glomerulosclerosis (FSGS) can be separated into primary, genetic or secondary causes. Primary disease results in nephrotic syndrome while genetic and secondary forms may be associated with asymptomatic proteinuria or with nephrotic syndrome. Overall only about 20% of patients with FSGS experience a partial or complete remission of nephrotic syndrome with treatment. FSGS progresses to kidney failure in about half of the cases. This is an update of a review first published in 2008.

OBJECTIVES

To assess the benefits and harms of immunosuppressive and non-immunosuppressive treatment regimens in adults with FSGS.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies to 21 June 2021 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs of any intervention for FSGS in adults were included. Studies comparing different types, routes, frequencies, and duration of immunosuppressive agents and non-immunosuppressive agents were assessed.

DATA COLLECTION AND ANALYSIS

At least two authors independently assessed study quality and extracted data. Statistical analyses were performed using the random-effects model and results were expressed as a risk ratio (RR) for dichotomous outcomes, or mean difference (MD) for continuous data with 95% confidence intervals (CI). Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

Fifteen studies (560 participants) were included. No studies specifically evaluating corticosteroids compared with placebo or supportive therapy were identified. Studies evaluated participants with steroid-resistant FSGS. Five studies (240 participants) compared cyclosporin with or without prednisone with different comparators (no specific treatment, prednisone, methylprednisolone, mycophenolate mofetil (MMF), dexamethasone). Three small studies compared monoclonal antibodies (adalimumab, fresolimumab) with other agents or placebo. Six single small studies compared rituximab with tacrolimus, cyclosporin plus valsartan with cyclosporin alone, MMF with prednisone, chlorambucil plus methylprednisolone and prednisone with no specific treatment, different regimens of dexamethasone and CCX140-B (an antagonist of the chemokine receptor CCR2) with placebo. The final study (109 participants) compared sparsentan, a dual inhibitor of endothelin Type A receptor and of the angiotensin II Type 1 receptor, with irbesartan. In the risk of bias assessment, seven and five studies were at low risk of bias for sequence generation and allocation concealment, respectively. Four studies were at low risk of performance bias and 14 studies were at low risk of detection bias. Thirteen, six and five studies were at low risk of attrition bias, reporting bias and other bias, respectively. Of five studies evaluating cyclosporin, four could be included in our meta-analyses (231 participants). Cyclosporin with or without prednisone compared with different comparators may increase the likelihood of complete remission (RR 2.31, 95% CI 1.13 to 4.73; I² = 1%; low certainty evidence) and of complete or partial remission (RR 1.64, 95% CI 1.10 to 2.44; I² = 19%) but not of partial remission (RR 1.36, 95% CI 0.78 to 2.39, I² = 22%). In Individual studies, cyclosporin with prednisone versus prednisone may increase the likelihood of partial (49 participants: RR 7.96, 95% CI 1.09 to 58.15) or complete or partial remission (49 participants: RR 8.85, 95% CI 1.22 to 63.92) but not of complete remission. The remaining individual comparisons may make little or no difference to the likelihood of complete remission, partial remission or complete or partial remission compared with no treatment, methylprednisolone, MMF, or dexamethasone. Individual study data and combined data showed that cyclosporin may make little or no difference to the outcomes of chronic kidney disease or kidney failure. It is uncertain whether cyclosporin compared with these comparators in individual or combined analyses makes any difference to the outcomes of hypertension or infection. MMF compared with prednisone may make little or no difference to the likelihood of complete remission (33 participants: RR 1.05, 95% CI 0.58 to 1.88; low certainty evidence), partial remission, complete or partial remission, glomerular filtration rate, or infection. It is uncertain whether other interventions make any difference to outcomes as the certainty of the evidence is very low. It is uncertain whether sparsentan reduces proteinuria to a greater extent than irbesartan.

AUTHORS' CONCLUSIONS

No RCTs, which evaluated corticosteroids, were identified although the KDIGO guidelines recommend corticosteroids as the first treatment for adults with FSGS. The studies identified included participants with steroid-resistant FSGS. Treatment with cyclosporin for at least six months was more likely to achieve complete remission of proteinuria compared with other treatments but there was considerable imprecision due to few studies and small participant numbers. In future studies of existing or new interventions, the investigators must clearly define the populations included in the study to provide appropriate recommendations for patients with primary, genetic or secondary FSGS.

Later Response to Corticosteroids in Adults With Primary Focal Segmental Glomerular Sclerosis Is Associated With Favorable Outcomes

INTRODUCTION

Guidelines advise initial therapy with corticosteroids (CSs) in patients with presumed primary focal segmental glomerular sclerosis (pFSGS). Many patients do not achieve complete remission (CR) after 8 or 16 weeks. Although these patients are considered steroid resistant, clinical outcomes are ill defined.

METHODS

A retrospective cohort study of patients with pFSGS who were referred between January 1995 and December 2014. Data of clinical presentation until last follow-up were collected from patient records.

RESULTS

A total of 51 patients (median age 47 years, 20 female/31 male) were included (median follow-up 7.1 years). There were 10 patients who achieved partial response (PR) at 8 weeks. High-dose CS monotherapy was continued for a median of 17 weeks (interquartile range [IQR] 11-21 weeks) (total duration 56 weeks [IQR 28-83 weeks]). With CSs, the cumulative incidence of CR + PR was 18% and 35%, respectively. Of 24 patients with persistent nephrotic-range proteinuria, 22 received additional immunosuppressive (IS) therapy, resulting in CR in 3 (14%) and PR in 11 patients (50%). A decrease of >20% of proteinuria at 8 weeks predicted response. In addition, 8 patients (36%) were considered primary nonresponders. A genetic cause was found in 2 patients. Proteinuria at end of follow-up was 1.2 g (IQR 0.4-3.0 g/24 hours or g/10 mmol creatinine). Renal survival at 3, 5, and 10 years was 92%, 87%, and 64%, respectively.

CONCLUSION

Patients with presumed pFSGS often respond late to IS therapy. A decrease in proteinuria of >20% after 8 weeks of therapy is a predictor of responsiveness. Regardless of CR in some patients, improved biomarkers are needed to predict response/outcomes in patients with pFSGS.

Safety and Efficacy of GFB-887, a TRPC5 Channel Inhibitor, in Patients With Focal Segmental Glomerulosclerosis, Treatment-Resistant Minimal Change Disease, or Diabetic Nephropathy: TRACTION-2 Trial Design

Introduction

A critical unmet need exists for precision therapies for chronic kidney disease. GFB-887 is a podocyte-targeting, small molecule inhibitor of transient receptor potential canonical-5 (TRPC5) designed specifically to treat patients with glomerular kidney diseases characterized by an overactivation of the TRPC5-Rac1 pathway. In a first-in-human study, GFB-887 was found to be safe and well tolerated, had a pharmacokinetic (PK) profile allowing once-daily dosing, and dose dependently decreased urinary Rac1 in healthy adults.

Methods

TRACTION-2 is a phase 2a, double-blind, placebo-controlled, multiple-ascending dose study of GFB-887 in patients with focal segmental glomerulosclerosis (FSGS), treatment-resistant minimal change disease (TR-MCD), or diabetic nephropathy (DN) (NCT04387448). Adult patients on stable renin-angiotensin system blockade and/or immunosuppression with persistent proteinuria will be randomized and dosed in 3 ascending dose levels to GFB-887 or placebo for 12 weeks. Cohorts may be expanded or biomarker-enriched depending upon results of an adaptive interim analysis.

Results

The primary objective is to evaluate the effect of increasing doses of GFB-887 on proteinuria. Safety and tolerability, quality of life, pharmacokinetic/pharmacodynamic profiles, and the potential association of urinary Rac1 with efficacy will also be evaluated. The projected sample size has 80% power to detect a treatment difference in proteinuria of 54% (FSGS/TR-MCD) or 44% (DN) compared to placebo.

Conclusion

TRACTION-2 will explore whether targeted blockade of the TRPC5-Rac1 pathway with GFB-887 is an efficacious and safe treatment strategy for patients with FSGS, TR-MCD, and DN and the potential value of urinary Rac1 as a predictive biomarker of treatment response.

Perspectives in membranous nephropathy

The identification of the phospholipase A2 receptor 1 (PLA2R) and thrombospondin type-1 domain-containing protein 7A (THSD7A) as podocyte antigens in adult patients with membranous nephropathy (MN) has strongly impacted both experimental and clinical research on this disease. Evidence has been furnished that podocyte-directed autoantibodies can cause MN, and novel PLA2R- and THSD7A-specific animal models have been developed. Today, measurement of serum autoantibody levels and staining of kidney biopsies for the target antigens guides MN diagnosis and treatment worldwide. Additionally, anti-PLA2R antibodies have been proven to be valuable prognostic biomarkers in MN. Despite these impressive advances, a variety of questions regarding the disease pathomechanisms, clinical use of antibody measurement, and future treatments remain unanswered. In this review, we will outline recent advances made in the field of MN and discuss open questions and perspectives with a focus on novel antigen identification, mechanisms of podocyte injury, clinical use of antibody measurement to guide diagnosis and treatment, and the potential of innovative, pathogenesis-based treatment strategies.

Autoimmunity in Focal Segmental Glomerulosclerosis: A Long-Standing Yet Elusive Association

Focal segmental glomerulosclerosis (FSGS) is a histological term that describes a pathologic renal entity affecting both adults and children, with a wide array of possible underlying etiologies. Podocyte damage with scarring, the hallmark of this condition, leads to altered permeability of the glomerular barrier, which may result in massive proteinuria and relentless renal function deterioration. A definite cause of focal segmental glomerulosclerosis can be confirmed in a minority of cases, while most forms have been traditionally labeled as primary or idiopathic. Despite this definition, increasing evidence indicates that primary forms are a heterogenous group rather than a single disease entity: several circulating factors that may affect glomerular permeability have been proposed as potential culprits, and both humoral and cellular immunity have been implicated in the pathogenesis of the disease. Consistently, immunosuppressive drugs are considered as the cornerstone of treatment for primary focal segmental glomerulosclerosis, but response to these agents and long-term outcomes are highly variable. In this review we provide a summary of historical and recent advances on the pathogenesis of primary focal segmental glomerulosclerosis, focusing on implications for its differential diagnosis and treatment.

Utility of Columbia classification in focal segmental glomerulosclerosis: renal prognosis and treatment response among the pathological variants

BACKGROUND

The utility of the Columbia classification (Col-class) for focal segmental glomerulosclerosis (FSGS) has not yet been fully proven.

METHODS

We extracted 201 FSGS patients from 10 nephrology centers in Japan and investigated the difference of a composite renal endpoint, defined as doubling of serum creatinine and/or development of end-stage renal disease, in pathological variants. Sensitivity analysis was used to prove the utility of the Col-class to predict renal outcomes. Additionally, the renal protective effects of steroids and/or immunosuppression (steroid/IS) were investigated in patients stratified according to the Col-class.

RESULTS

The patients were classified into the following variants: not otherwise specified [NOS; n = 121 (60.1%)], perihilar [n = 31 (15.4%)], cellular [n = 19 (9.5%)], tip [n = 17 (8.5%)] and collapsing [n = 13 (6.5%)]. No tip variant patients reached the renal endpoint. The renal outcome in the collapsing variant was significantly poorer than that in the NOS [hazard ratio (HR) 3.71; P = 0.005]. In the sensitivity analysis, the area under the receiver operating characteristic curve for the renal endpoint was increased by adding Col-class to a model including common risk factors (P = 0.021). In a subgroup treated without steroid/IS, the outcome in the cellular variant was worse than that in the NOS (HR 5.10; P = 0.040) but the difference was not observed in the subgroup with steroid/IS (HR 0.54; P = 0.539).

CONCLUSIONS

The Col-class is useful to predict renal prognosis in Japanese patients with FSGS. In addition to good prognosis in the tip variant and poor in the collapsing variant, good clinical course in the cellular variant treated with steroid/IS was suggested.

Management of Patients With Glomerulonephritis During the COVID-19 Pandemic: Recommendations From the Canadian Society of Nephrology COVID-19 Rapid Response Team

PURPOSE OF PROGRAM

This article will provide guidance on how to best manage patients with glomerulonephritis (GN) during the COVID-19 pandemic.

SOURCES OF INFORMATION

We reviewed relevant published literature, program-specific documents, and guidance documents from international societies. An informal survey of Canadian nephrologists was conducted to identify practice patterns and expert opinions. We hosted a national webinar with invited input and feedback after webinar.

METHODS

The Canadian Society of Nephrology (CSN) Board of Directors invited physicians with expertise in GN to contribute. Specific COVID-19-related themes in GN were identified, and consensus-based recommendations were made by this group of nephrologists. The recommendations received further peer input and review by Canadian nephrologists via a CSN-sponsored webinar. This was attended by 150 kidney health care professionals. The final consensus recommendations also incorporated review by Editors of the Canadian Journal of Kidney Health and Disease.

KEY FINDINGS

We identified 9 areas of GN management that may be affected by the COVID-19 pandemic: (1) clinic visit scheduling, (2) clinic visit type, (3) provision of multidisciplinary care, (4) blood and urine testing, (5) home-based monitoring essentials, (6) immunosuppression, (7) other medications, (8) patient education and support, and (9) employment.

LIMITATIONS

These recommendations are expert opinion, and are subject to the biases associated with this level of evidence. To expedite the publication of this work, a parallel review process was created that may not be as robust as standard arm's length peer review processes.

IMPLICATIONS

These recommendations are intended to provide optimal care during the COVID-19 pandemic. Our recommendations may change based on the evolving evidence.

Rituximab in adult minimal change disease and focal segmental glomerulosclerosis - What is known and what is still unknown?

Primary forms of minimal change disease and focal segmental glomerulosclerosis are rare podocytopathies and clinically characterized by nephrotic syndrome. Glucocorticoids are the cornerstone of the initial immunosuppressive treatment in these two entities. Especially among adults with minimal change disease or focal segmental glomerulosclerosis, relapses, steroid dependence or resistance are common and necessitate re-initiation of steroids and other immunosuppressants. Effective steroid-sparing therapies and introduction of less toxic immunosuppressive agents are urgently needed to reduce undesirable side effects, in particular for patients whose disease course is complex. Rituximab, a B cell depleting monoclonal antibody, is increasingly used off-label in these circumstances, despite a low level of evidence for adult patients. Hence, critical questions concerning drug-safety, long-term efficacy and the optimal regimen for rituximab-treatment remain unanswered. Evidence in the form of large, multicenter studies and randomized controlled trials are urgently needed to overcome these limitations.

Focal Segmental Glomerulosclerosis: State-of-the-Art and Clinical Perspective

Focal segmental glomerulosclerosis (FSGS) is a histological pattern of glomerular injury, rather than a single disease, that is caused by diverse clinicopathological entities with different mechanisms of injury with the podocyte as the principal target of lesion, leading to the characteristic sclerotic lesions in parts (i.e., focal) of some (i.e., segmental) glomeruli. The lesion of FSGS has shown an increasing prevalence over the past few decades and is considered the most common glomerular cause leading to ESKD. Primary FSGS, which usually presents with nephrotic syndrome, is thought to be caused by circulating permeability factors that have a main role in podocyte foot process effacement. Secondary forms of FSGS include maladaptive FSGS secondary to glomerular hyperfiltration such as in obesity or in cases of loss in nephron mass, virus-associated FSGS, and drug-associated FSGS that can result in direct podocyte injury. Genetic FSGS is increasingly been recognized and a careful evaluation of patients with atypical primary or secondary FSGS should be performed to exclude genetic causes. Unlike primary FSGS, secondary and genetic forms of FSGS do not respond to immunosuppression and tend not to recur after kidney transplantation. Distinguishing primary FSGS from secondary and genetic causes has a prognostic significance and is crucial for an appropriate management. In this review, we examine the pathogenesis, clinical approach to distinguish between the different causes, and current recommendations in the management of FSGS.

Response to First Course of Intensified Immunosuppression in Genetically Stratified Steroid Resistant Nephrotic Syndrome

BACKGROUND AND OBJECTIVES

Intensified immunosuppression in steroid-resistant nephrotic syndrome is broadly applied, with disparate outcomes. This review of patients from the United Kingdom National Study of Nephrotic Syndrome cohort aimed to improve disease stratification by determining, in comprehensively genetically screened patients with steroid-resistant nephrotic syndrome, if there is an association between response to initial intensified immunosuppression and disease progression and/or post-transplant recurrence.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Pediatric patients with steroid-resistant nephrotic syndrome were recruited via the UK National Registry of Rare Kidney Diseases. All patients were whole-genome sequenced, whole-exome sequenced, or steroid-resistant nephrotic syndrome gene-panel sequenced. Complete response or partial response within 6 months of starting intensified immunosuppression was ascertained using laboratory data. Response to intensified immunosuppression and outcomes were analyzed according to genetic testing results, pattern of steroid resistance, and first biopsy findings.

RESULTS

Of 271 patients, 178 (92 males, median onset age 4.7 years) received intensified immunosuppression with response available. A total of 4% of patients with monogenic disease showed complete response, compared with 25% of genetic-testing-negative patients (P=0.02). None of the former recurred post-transplantation. In genetic-testing-negative patients, 97% with complete response to first intensified immunosuppression did not progress, whereas 44% of nonresponders developed kidney failure with 73% recurrence post-transplant. Secondary steroid resistance had a higher complete response rate than primary/presumed resistance (43% versus 23%; P=0.001). The highest complete response rate in secondary steroid resistance was to rituximab (64%). Biopsy results showed no correlation with intensified immunosuppression response or outcome.

CONCLUSIONS

Patients with monogenic steroid-resistant nephrotic syndrome had a poor therapeutic response and no post-transplant recurrence. In genetic-testing-negative patients, there was an association between response to first intensified immunosuppression and long-term outcome. Patients with complete response rarely progressed to kidney failure, whereas nonresponders had poor kidney survival and a high post-transplant recurrence rate. Patients with secondary steroid resistance were more likely to respond, particularly to rituximab.

Rituximab in maintaining remission in adults with podocytopathy

Rituximab is currently used after the conventional agents have failed in the management of steroid-dependent (SD)/ steroid-resistant (SR) podocytopathies and have a safer toxicity profile. We report 53 adults with podocytopathies who were managed effectively with CD19-targeted rituximab therapy.

METHODS

This was a prospective study carried out at a tertiary care centre in India between January 2014 and June 2019. Adults between 16 and 60 years with SD, frequently relapsing (FR), and SR nephrotic syndrome (NS) due to podocytopathy received rituximab in a CD19-targeted approach.

PRIMARY OUTCOME

Percentage of patients who were in remission at 6 and 12 months. Secondary outcome: Percentage of patients in remission at the last follow-up, rituximab dose and adverse events of rituximab therapy.

RESULTS

Fifty-three adults with SD/FR/SR NS received CD19-targeted rituximab. The median age at the time of first rituximab injection was 30.09 ± 13.21 (16.53) years. At the time of first rituximab infusion, all patients were in remission with steroids and/or calcineurin inhibitors (CNIs). Fifty (94.33%) patients were in remission at the end of 6 and 12 months and the last follow-up (median: 36 months). The mean total dose of rituximab at 1 year was 788.7 ± 128.1 (6 001 100) mg. At last follow-up (median 36 months), 42 (79%) patients did not require any additional CNI or steroids therapy. No serious adverse events to rituximab were noted.

CONCLUSION

CD19-targeted rituximab therapy is safe and efficacious in the management of SD/SR adult podocytopathy. Also, rituximab is effective in maintaining remission in treatment naïve adult SD or FR podocytopathy.

Rituximab in kidney disease and transplant

Rituximab is a chimeric monoclonal antibody that binds to CD20 antigen of B-cells. It depletes the level of mature B-cells by various mechanisms such as mediation of antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity, and B-cell apoptosis. Rituximab is a USFDA approved drug for clinical use in non-Hodgkin's B-cell lymphoma (NHL), rheumatoid arthritis, chronic lymphocytic leukemia (CLL), granulomatosis with polyangiitis and pemphigus vulgaris. It is also known for its "off label" use in renal disease and renal transplant worldwide. However, the exact mechanisms by which it exerts its effect in the aforementioned condition remain unclear but may be related to its long-term effects on plasma cell development and the impact on B-cell modulation of T cell responses. This review discusses the current use of rituximab in renal disease and renal transplantation, and its potential role in novel therapeutic protocols.

European Society of Pediatric Nephrology survey on current practice regarding recurrent focal segmental glomerulosclerosis after pediatric kidney transplantation

INTRODUCTION

Primary FSGS is an important cause of ESRD in children. FSGS recurrence after kidney transplantation is associated with early graft loss. No guidelines for treatment of FSGS recurrence exist. We conducted a survey to gain insight into variation of treatment between centers.

METHODS

A survey was sent to all members of the ESPN on behalf of the "Renal Transplantation" and "Idiopathic Nephrotic Syndrome" working groups.

RESULTS

Fifty-nine nephrologists from 31 countries responded, reporting 807 FSGS patients, with 241 (30%) FSGS recurrences after transplantation. Recurrence varied from 0% to 100% between respondents. Native nephrectomy before or during transplantation was performed, respectively, always (37%), never (39%), or on clinical indication (17%). Half of the respondents started preventive treatment before transplantation, using PF (n = 10); R (n = 4); PF or IA, plus R (n = 9); cyclosporine (n = 2); or unknown (n = 4). Immunosuppressive therapy for patients without known mutations consisted of a combination of steroids, tacrolimus/cyclosporine, and MMF, with or without IL-2R-blockade in, respectively, 61% and 86% of the respondents. Sixty-three percent applied a similar regimen to patients with known mutations. FSGS recurrence was treated with PF or IA, plus R by 66% of respondents; 54% observed no response. Complete remission in >50% of patients was reported by 41% of the respondents.

DISCUSSION

FSGS recurrence after transplantation is common, but varies greatly between centers. We found great variability in preventive and therapeutic treatment regimens. Future research should focus on predisposing factors, including biopsy findings and genetic mutations, and standardized treatment.

Steroid-resistentes nephrotisches Syndrom

Das steroid-resistente nephrotische Syndrom (SRNS) mit dem histomorphologischen Korrelat der fokal-segmentalen Glomerulosklerose (FSGS) stellt eine bedeutende Ursache für eine terminale Niereninsuffizienz im Kindesalter, aber auch bei erwachsenen Patienten dar. Das Erkrankungsspektrum zeichnet sich durch eine große genetische Heterogenität aus, wobei auch nicht genetische Ursachen bei der FSGS beobachtet werden. Die genetische Grundlage des SRNS/FSGS-Komplexes ist v. a. für ältere Kinder/Jugendliche und Erwachsene bisher noch unzureichend verstanden. Die eindeutige Abgrenzung genetischer SRNS/FSGS-Ursachen ist unerlässlich, da sich bereits heute hieraus eine Vielzahl an klinischen Implikationen ergeben. Die Identifikation unbekannter Erkrankungsallele oder Erkrankungsgene kann zudem Erkenntnisse bringen, die ein gänzlich neues Verständnis der Pathomechanismen ermöglichen. Durch umfassende genetische Untersuchungen besteht die Möglichkeit, die ungelöste genetische Basis der Rekurrenz der FSGS-Erkrankung bei bislang Varianten-negativen Patienten zu finden.

Calcineurin Inhibitors With Reduced-Dose Steroids as First-Line Therapy for Focal Segmental Glomerulosclerosis

Introduction

High-dose corticosteroids remain the first-line therapy for focal and segmental glomerulosclerosis (FSGS), whereas calcineurin inhibitors (CNIs) are reserved for those patients resistant to corticosteroid therapy.

Methods

This is a retrospective cohort analysis in patients with primary FSGS diagnosed between 2007 and 2014. According to the administered treatment, patients were segregated into 3 groups: high-dose prednisone, first-line CNIs plus low-dose prednisone, and rescue CNIs. Cumulative corticosteroid doses were compared as well as response to therapy and long-term renal survival by Cox regression analysis.

Results

A total of 66 patients were included (39 treated with high-dose prednisone, 11 treated with first-line CNI, 16 treated with high-dose prednisone followed by rescue CNI). Cumulative doses of prednisone in the high-dose group were 9.3 g (interquartile range [IQR] = 7.5−12.5 g), compared to 2.5 g (IQR = 1.82−3.12 g) in the first-line CNI plus low-dose corticosteroid group and 13.8 g (IQR = 9.2−15.8 g) rescue CNI groups, respectively (P < 0.001). Time under corticosteroid management was also higher in the high-dose prednisone group compared to the first-line CNI group. There was a response to treatment in 76.9%, 72.7%, and 87.5% of high-dose prednisone, first-line CNI and rescue CNI groups, with complete remission in 48.7%, 36.4%, and 31.3% respectively. There was no difference in relapse incidence after treatment (48.4%, 44.4%, and 46.7%) or in 5-year renal survival (87.2%, 81.8%, and 87.5%). Baseline proteinuria, biopsy chronicity score, and response to therapy were independent predictors of renal survival.

Conclusion

An initial CNI plus low-dose corticosteroid approach in primary FSGS reduces corticosteroid exposure with a response-to-therapy rate similar to that of the currently recommended high-dose corticosteroid regimen. These findings justify a randomized trial to formally test this hypothesis.

Continuous B-cell depletion in frequently relapsing, steroid-dependent and steroid-resistant nephrotic syndrome

Background

Patients with frequently relapsing (FR), steroid-dependent (SD) and steroid-resistant (SR) nephrotic syndrome are a therapeutic challenge with limited treatment options. Here, we retrospectively analyze the efficacy and safety of rituximab-induced continuous B-cell depletion in these populations.

Methods

Patients were included if they were at least 18 years of age and had FR, SD or SR minimal change disease (MCD) or primary focal segmental glomerulosclerosis (FSGS) and were treated with a strategy of continuous B-cell depletion. Partial remission (PR) was defined as a urinary protein:creatinine ratio (UPCR) of ≤3.5 g/g and a 50% reduction in the UPCR from baseline. Complete remission (CR) was defined as a UPCR ≤0.3 g/g.

Results

We identified 20 patients with MCD (n = 13) or FSGS (n = 7) who fulfilled the inclusion criteria. All patients had either SD (n = 12), SR (n = 7) or FR (n = 1) disease. Patients received a median of nine rituximab doses [interquartile range (IQR) 7.5, 11] and were treated for a median time of 28 months (IQR 23, 41). Prednisone was weaned from a median of 60 mg daily (IQR 40, 60) at rituximab initiation to 4.5 mg daily (IQR 0, 5.5) by 12 months. All patients achieved PR. CR occurred in 11 of 13 patients with FR or SD disease, but only 1 of 7 patients with SR disease (logrank P = 0.01). Four relapses occurred, all in patients with SR disease. Three serious infections occurred over 70.3 patient-years.

Conclusion

Continuous B-cell depletion is a therapeutic option in the management of complicated nephrotic syndrome. Additional studies are needed to clarify the utility of this strategy.

Protecting Podocytes: A Key Target for Therapy of Focal Segmental Glomerulosclerosis

BACKGROUND

Focal segmental glomerulosclerosis (FSGS) is a histologic pattern of injury demonstrated by renal biopsy that can arise from a diverse range of causes and mechanisms. It has an estimated incidence of 7 per 1 million and is the most common primary glomerular disorder leading to end-stage renal disease in the United States. This review focuses on damage to the podocyte and the consequences of this injury in patients with FSGS, the genetics of FSGS, and approaches to treatment with a focus on the effects on podocytes.

SUMMARY

The podocyte is central to the glomerular filtration barrier and is particularly vulnerable because of its highly differentiated post-mitotic phenotype. The progressive structural changes involved in the pathology of FSGS include podocyte foot process effacement, death of podocytes and exposure of the glomerular basement membrane, filtration of nonspecific plasma proteins, expansion of capillaries, misdirected filtration at points of synechiae, and mesangial matrix proliferation. Although damage to and death of podocytes can result from single-gene disorders, evidence also suggests a role for soluble factors, such as soluble urokinase-type plasminogen activator receptor, cardiotrophin-like cytokine-1, and anti-CD40 antibodies, that promote FSGS recurrence post transplant. Several classes of medications, including corticosteroids, calcineurin inhibitors, endothelin receptor antagonists, adrenocorticotropic hormone, and rituximab, have been shown to be effective for the treatment of FSGS and have been demonstrated to have significant protective effects on podocytes. Key Messages: Greater understanding of podocyte biology is essential to the identification of new treatment targets and medications for the management of patients with FSGS.

The Role of Glucocorticoid Receptors in Podocytes and Nephrotic Syndrome

Glucocorticoid receptor (GC), a founding member of the nuclear hormone receptor superfamily, is a glucocorticoid-activated transcription factor that regulates gene expression and controls the development and homeostasis of human podocytes. Synthetic glucocorticoids are the standard treatment regimens for proteinuria (protein in the urine) and nephrotic syndrome (NS) caused by kidney diseases. These include minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN) and immunoglobulin A nephropathy (IgAN) or subsequent complications due to diabetes mellitus or HIV infection. However, unwanted side effects and steroid-resistance remain major issues for their long-term use. Furthermore, the mechanism by which glucocorticoids elicit their renoprotective activity in podocyte and glomeruli is poorly understood. Podocytes are highly differentiated epithelial cells that contribute to the integrity of kidney glomerular filtration barrier. Injury or loss of podocytes leads to proteinuria and nephrotic syndrome. Recent studies in multiple experimental models have begun to explore the mechanism of GC action in podocytes. This review will discuss progress in our understanding of the role of glucocorticoid receptor and glucocorticoids in podocyte physiology and their renoprotective activity in nephrotic syndrome.

Focal segmental glomerulosclerosis in children complicated by posterior reversible encephalopathy syndrome

An uncommon side effect of cyclosporine A (CsA) use is posterior reversible encephalopathy syndrome (PRES). PRES usually develops because of disturbed capacity of posterior cerebral blood flow to autoregulate an acute rise in blood pressure. We present the case of a 10-year-old girl who was previously diagnosed in our department with focal segmental glomerulosclerosis. She was treated with CsA and developed seizures, progressive loss of consciousness, and visual disturbance on the 7th day of treatment. Brain magnetic resonance imaging showed degeneration of white matter with diffuse demyelination in the parietal and posterior occipital lobes, consistent with the diagnosis of PRES. Cases of PRES reported in children are usually secondary to immunosuppressive therapy in oncological and haematological diseases. Our case is the fifth reported case of focal segmental glomerulosclerosis in children treated with CsA and complicated by PRES. Rapid recognition of PRES and stopping neurotoxic therapy early are essential for a good prognosis.

Exploring the Clinical and Genetic Spectrum of Steroid Resistant Nephrotic Syndrome: The PodoNet Registry

Background: Steroid resistant nephrotic syndrome (SRNS) is a rare condition, accounting for 10-15% of all children with idiopathic nephrotic syndrome. SRNS can be caused by genetic abnormalities or immune system dysfunction. The prognosis of SRNS varies from permanent remission to progression to end-stage kidney disease, and post-transplant recurrence is common. Objectives: The PodoNet registry project aims to explore the demographics and phenotypes of immune-mediated and genetic forms of childhood SRNS, to assess genotype-phenotype correlations, to evaluate clinical management and long-term outcomes, and to search for novel genetic entities and diagnostic and prognostic biomarkers in SRNS. Methods: In 2009, an international registry for SRNS was established to collect retro- and prospective information on renal and extrarenal disease manifestations, histopathological and genetic findings and information on family history, pharmacotherapy responsiveness and long-term outcomes. To date, more than 2,000 patients have been enrolled at 72 pediatric nephrology centers, constituting the largest pediatric SRNS cohort assembled to date. Results: In the course of the project, traditional Sanger sequencing was replaced by NGS-based gene panel screening covering over 30 podocyte-related genes complemented by whole exome sequencing. These approaches allowed to establish genetic diagnoses in 24% of the patients screened, widened the spectrum of genetic disease entities presenting with SRNS phenotype (COL4A3-5, CLCN5), and contributed to the discovery of new disease causing genes (MYOE1, PTPRO). Forty two percent of patients responded to intensified immunosuppression with complete or partial remission of proteinuria, whereas 58% turned out multi-drug resistant. Medication responsiveness was highly predictive of a favorable long-term outcome, whereas the diagnosis of genetic disease was associated with a high risk to develop end-stage renal disease during childhood. Genetic SRNS forms were generally resistant to immunosuppressive treatment, justifying to avoid such pharmacotherapies altogether once a genetic diagnosis is established. Even symptomatic anti-proteinuric treatment with RAS antagonists seems to be challenging and of limited efficacy in genetic forms of SRNS. The risk of post-transplant disease recurrence was around 30% in non-genetic SRNS whereas it is negligible in genetic cases. Conclusion: In summary, the PodoNet Registry has collected detailed clinical and genetic information in a large SRNS cohort and continues to generate fundamental insights regarding demographic and etiological disease aspects, genotype-phenotype associations, the efficacy of therapeutic strategies, and long-term patient and renal outcomes including post-transplant disease recurrence.

Are Tacrolimus Pharmacokinetics Affected by Nephrotic Stage?

BACKGROUND

Although tacrolimus therapy is not the first-line therapy for childhood nephrotic syndrome, it is often used instead of cyclosporine to ameliorate the side effects. The pharmacokinetics (PK) of tacrolimus (Tac) can be influenced by many conditions, and it has a high plasma protein binding. The Tac PK during relapse and remission of childhood nephrotic syndrome has not been well described.

METHODS

We performed 14 PK profiles (with measurements before intake and 0.5, 1, 2, 4, and 12 hours postintake) in 7 children with steroid-resistant nephrotic syndrome at week 1 (all nephrotic) and week 16 after Tac therapy (all in remission). These data were compared with historical PK data of 161 PK profiles in 87 pediatric renal transplant recipients with measurements before intake and 0.5, 1, 1.5, 2, 3, 4, 6, 8, and 12 hours postintake. Tac levels were measured using the Abbott Tacro II assay. We used descriptive statistics to generate percentiles and compared these with those of patients with steroid-resistant nephrotic syndrome.

RESULTS

The median age of patients with nephrotic syndrome was 3.2 years (range 2.5, 17.2), male gender 71.4%, significantly younger than the control group. Median Tac dose was similar during both PK profiles (0.11 mg·kg·d at week 1 versus 0.13 mg·kg·d at week 16, P = 0.81). There were no statistically significant differences in median dose-normalized area-under-the-time-concentration profiles, peak concentration, time to reach peak concentration, and Tac trough levels. Individual dose-normalized Tac levels for each time point during the PK profile were also not different (P = 0.81).

CONCLUSIONS

We conclude that Tac PK profiles are unaltered during relapse of nephrotic syndrome.

Immunosuppressive therapy for steroid-resistant nephrotic syndrome: a Bayesian network meta-analysis of randomized controlled studies

BACKGROUND

The purpose of this study was to conduct a meta-analysis examining the efficacy of cyclophosphamide, cyclosporin, and tacrolimus in treating steroid resistant nephrotic syndrome.

METHODS

Medline, Cochrane, EMBASE, and Google Scholar were searched until May 02, 2017 using the keywords: immunosuppressive therapy, steroid-resistant nephrotic syndrome, cyclophosphamide, cyclosporine A, and tacrolimus. Inclusion criteria were randomized controlled trials (RCTs) including patients with SRNS treated with an immunosuppressive therapy or placebo.

RESULTS

Seven RCTs were included, and the number of patients ranged from 30 to 131. Conventional pair-wise meta-analysis indicated a higher odds of complete or partial remission with tacrolimus as compared to cyclophosphamide [odds ratio (OR) 4.908, 95% confidence interval (CI) 2.278-10.576, P < 0.001], and cyclophosphamide (OR 0.143, 95% CI 0.028-0.721, P = 0.019) and placebo (OR 0.043, 95% CI 0.012-0.157, P < 0.001) were associated with a lower likelihood of complete or partial remission than cyclosporine. Bayesian analysis indicated that tacrolimus and cyclosporine were the best and the second-best agents for inducing a complete or partial remission (rank probability = 0.53 for tacrolimus and 0.46 for cyclosporine).

CONCLUSION

As compared to cyclophosphamide and cyclosporin, tacrolimus is more effective at inducing remission in patients with SRNS.

Long-Term Outcome of Steroid-Resistant Nephrotic Syndrome in Children

We investigated the value of genetic, histopathologic, and early treatment response information in prognosing long-term renal outcome in children with primary steroid-resistant nephrotic syndrome. From the PodoNet Registry, we obtained longitudinal clinical information for 1354 patients (disease onset at >3 months and <20 years of age): 612 had documented responsiveness to intensified immunosuppression (IIS), 1155 had kidney biopsy results, and 212 had an established genetic diagnosis. We assessed risk factors for ESRD using multivariate Cox regression models. Complete and partial remission of proteinuria within 12 months of disease onset occurred in 24.5% and 16.5% of children, respectively, with the highest remission rates achieved with calcineurin inhibitor-based protocols. Ten-year ESRD-free survival rates were 43%, 94%, and 72% in children with IIS resistance, complete remission, and partial remission, respectively; 27% in children with a genetic diagnosis; and 79% and 52% in children with histopathologic findings of minimal change glomerulopathy and FSGS, respectively. Five-year ESRD-free survival rate was 21% for diffuse mesangial sclerosis. IIS responsiveness, presence of a genetic diagnosis, and FSGS or diffuse mesangial sclerosis on initial biopsy as well as age, serum albumin concentration, and CKD stage at onset affected ESRD risk. Our findings suggest that responsiveness to initial IIS and detection of a hereditary podocytopathy are prognostic indicators of favorable and poor long-term outcome, respectively, in children with steroid-resistant nephrotic syndrome. Children with multidrug-resistant sporadic disease show better renal survival than those with genetic disease. Furthermore, histopathologic findings may retain prognostic relevance when a genetic diagnosis is established.

Investigational drugs in development for focal segmental glomerulosclerosis

INTRODUCTION

Focal segmental glomerulosclerosis is an important cause of end stage kidney disease and is a paradigm for the study of glomerular scarring. There are no FDA approved treatments for this condition. Current therapies, assessed based on reduction in proteinuria, are generally effective in a subset of patients which suggests that FSGS is a heterogeneous group of glomerular disorders or podocytopathies that converge on a common histopathological phenotype. Areas covered: We searched for investigational drugs agents that target different pathophysiological pathways using the key words 'FSGS' and 'podocyte' in American and European clinical trial registers (clinicaltrials.gov; clinicaltrialsregister.eu). Published articles were searched in PubMed, Medline, the Web of Science and the Cochrane Central Register of Controlled Trials Library. Expert opinion: Progress is being made in defining the mechanism of action of subtypes of FSGS. Current and investigational therapies for FSGS target these different pathways of injury. It is anticipated that advances in systems biology will further refine the classification of FSGS by subdividing the disease based on the primary mechanism of glomerular injury, identify biomarkers to discriminate between different subtypes, and enable appropriate selection of appropriate therapy for each individual in accordance with the goals of precision medicine.

Safety and Efficacy of Combination ACTHar Gel and Tacrolimus in Treatment-Resistant Focal Segmental Glomerulosclerosis and Membranous Glomerulopathy

Introduction

H.P. ACTHar gel is a preparation of melanocortin peptides that has been used to treat resistant forms of nephrotic syndrome. To determine whether combination therapy with ACTHar gel and tacrolimus reduces proteinuria and stabilizes renal function, we conducted a prospective, open-label trial in patients with treatment-resistant membranous glomerulopathy (MGN) and focal segmental glomerulosclerosis (FSGS).

Methods

Nine patients with treatment-resistant MGN and 13 with treatment-resistant FSGS received subcutaneous ACTHar gel for 6 months. Patients with no response or a partial response to ACTHar gel alone received an additional 6 months of therapy with combination ACTHar gel and oral tacrolimus. The study endpoint was the percentage of patients achieving a complete or partial remission after 6 months of combination therapy.

Results

Among patients with MGN, treatment with ACTHar gel alone achieved a partial remission in 44% and no response in 56% of patients. No patient achieved a complete response with ACTHar gel therapy alone. An additional 6 months of combination therapy with ACTHar gel and tacrolimus resulted in partial and complete response rates of 25% and 75%, respectively. Among patients with FSGS, ACTHar gel therapy alone resulted in complete and partial response rate of 7.7% and 62.0%. Combination therapy increased complete response rates to 17% and partial responses to 66%. Proteinuria (urinary protein-to-creatinine ratio) was significantly reduced in both patients with MGN and those with FSGS after 6 months of ACTHar gel alone and was further reduced among the patients with MGN with the addition of tacrolimus. There were no significant changes in estimated glomerular filtration rate during the treatment phase or long-term follow-up.

Discussion

Combination therapy with ACTHar gel and tacrolimus was well tolerated by patients with treatment-resistant MGN and FSGS and significantly reduced proteinuria and improved clinical response rates compared with ACTHar gel alone.

Optimal management of primary focal segmental glomerulosclerosis in adults

Focal segmental glomerulosclerosis (FSGS) is a frequent glomerular kidney disease that is revealed by proteinuria or even nephrotic syndrome. A diagnosis can be established from a kidney biopsy that shows focal and segmental glomerulosclerosis. This histopathological lesion may be caused by a primary podocyte injury (idiopathic FSGS) but is also associated with other pathologies (secondary FSGS). The first-line treatment for idiopathic FSGS with nephrotic syndrome is a prolonged course of corticosteroids. However, steroid resistance or steroid dependence is frequent, and despite intensified immunosuppressive treatment, FSGS can lead to end-stage renal failure. In addition, in some cases, FSGS can recur on a graft after kidney transplantation: an unidentified circulating factor may be implicated. Understanding of its physiopathology is unclear, and it remains an important challenge for the scientific community to identify a specific diagnostic biomarker and to develop specific therapeutics. This study reviews the treatment of primary FSGS and the recurrence of FSGS after kidney transplantation in adults.

Recent Treatment Advances and New Trials in Adult Nephrotic Syndrome

The etiology of nephrotic syndrome is complex and ranges from primary glomerulonephritis to secondary forms. Patients with nephrotic syndrome often need immunosuppressive treatment with its side effects and may progress to end stage renal disease. This review focuses on recent advances in the treatment of primary causes of nephrotic syndrome (idiopathic membranous nephropathy (iMN), minimal change disease (MCD), and focal segmental glomerulosclerosis (FSGS)) since the publication of the KDIGO guidelines in 2012. Current treatment recommendations are mostly based on randomized controlled trials (RCTs) in children, small RCTs, or case series in adults. Recently, only a few new RCTs have been published, such as the Gemritux trial evaluating rituximab treatment versus supportive antiproteinuric and antihypertensive therapy in iMN. Many RCTs are ongoing for iMN, MCD, and FSGS that will provide further information on the effectiveness of different treatment options for the causative disease. In addition to reviewing recent clinical studies, we provide insight into potential new targets for the treatment of nephrotic syndrome from recent basic science publications.

A Phase 2, Double-Blind, Placebo-Controlled, Randomized Study of Fresolimumab in Patients With Steroid-Resistant Primary Focal Segmental Glomerulosclerosis

Introduction

Steroid-resistant focal segmental glomerulosclerosis (SR-FSGS) is a common glomerulopathy associated with nephrotic range proteinuria. Treatment goals are reduction in proteinuria, which can delay end-stage renal disease.

Methods

Patients with SR-FSGS were enrolled in a randomized, double-blind placebo-controlled trial of fresolimumab, a monoclonal anti−transforming growth factor−β antibody, at 1 mg/kg or 4 mg/kg for 112 days, followed double-blind for 252 days (NCT01665391). The primary efficacy endpoint was the percentage of patients achieving partial (50% reduction) or complete (< 300 mg/g Cr) remission of proteinuria.

Results

Of 36 enrolled patients, 10, 14, and 12 patients received placebo, fresolimumab 1 mg/kg, and fresolimumab 4 mg/kg, respectively. The baseline estimated glomerular filtration rate (eGFR) and urinary protein/creatinine ratio were 63 ml/min/1.73 m² and 6190 mg/g, respectively. The study was closed before reaching its target of 88 randomized patients. None of the prespecified efficacy endpoints for proteinuria reduction were achieved; however, at day 112, the mean percent change in urinary protein/creatinine ratio (a secondary efficacy endpoint) was –18.5% (P = 0.008), +10.5% (P = 0.52), and +9.0% (P = 0.91) in patients treated with fresolimumab 1 mg/kg, fresolimumab 4 mg/kg, and placebo, respectively. There was a nonsignificant trend toward greater estimated glomerular filtration rate decline in the placebo group compared to either of the fresolimumab-treated arms up to day 252.

Discussion

The study was underpowered and did not meet the primary or secondary endpoints. However, fresolimumab was well tolerated and is appropriate for continued evaluation in larger studies with adequate power.

Mycophenolate mofetil is inferior to tacrolimus in sustaining remission in children with idiopathic steroid-resistant nephrotic syndrome

Studies of nephrotic syndrome show that substitution of calcineurin inhibitors by mycophenolate mofetil (MMF) enables sustained remission and corticosteroid sparing and avoids therapy associated adverse effects. However, controlled studies in patients with steroid resistance are lacking. Here we examined the effect of switching from therapy with tacrolimus to MMF on disease course in an open-label, one-to-one randomized, controlled trial on children (one to 18 years old), recently diagnosed with steroid-resistant nephrotic syndrome, at a referral center in India. Following six months of therapy with tacrolimus, patients with complete or partial remission were randomly assigned such that 29 received MMF while 31 received tacrolimus along with tapering prednisolone on alternate days for 12 months. On intention-to-treat analyses, the proportion of patients with a favorable outcome (sustained remission, infrequent relapses) at one year was significantly lower (44.8%) in the MMF group than in the tacrolimus group (90.3%). The incidence of relapses was significantly higher for patients treated with MMF than tacrolimus (mean difference: 1.05 relapses per person-year). While there was no difference in the proportion of patients with sustained remission, the risk of recurrence of steroid resistance was significantly higher for patients receiving MMF compared to tacrolimus (mean difference: 20.7%). Compared to tacrolimus, patients receiving MMF had a significantly (71%) lower likelihood of a favorable outcome and significantly increased risk of treatment failure (frequent relapses, steroid resistance). Thus, replacing tacrolimus with MMF after six months of tacrolimus therapy for steroid-resistant nephrotic syndrome in children is associated with significant risk of frequent relapses or recurrence of resistance. These findings have implications for guiding the duration of therapy with tacrolimus for steroid-resistant nephrotic syndrome.

Focal Segmental Glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a leading cause of kidney disease worldwide. The presumed etiology of primary FSGS is a plasma factor with responsiveness to immunosuppressive therapy and a risk of recurrence after kidney transplant-important disease characteristics. In contrast, adaptive FSGS is associated with excessive nephron workload due to increased body size, reduced nephron capacity, or single glomerular hyperfiltration associated with certain diseases. Additional etiologies are now recognized as drivers of FSGS: high-penetrance genetic FSGS due to mutations in one of nearly 40 genes, virus-associated FSGS, and medication-associated FSGS. Emerging data support the identification of a sixth category: APOL1 risk allele-associated FSGS in individuals with sub-Saharan ancestry. The classification of a particular patient with FSGS relies on integration of findings from clinical history, laboratory testing, kidney biopsy, and in some patients, genetic testing. The kidney biopsy can be helpful, with clues provided by features on light microscopy (e.g, glomerular size, histologic variant of FSGS, microcystic tubular changes, and tubular hypertrophy), immunofluorescence (e.g, to rule out other primary glomerulopathies), and electron microscopy (e.g., extent of podocyte foot process effacement, podocyte microvillous transformation, and tubuloreticular inclusions). A complete assessment of renal histology is important for establishing the parenchymal setting of segmental glomerulosclerosis, distinguishing FSGS associated with one of many other glomerular diseases from the clinical-pathologic syndrome of FSGS. Genetic testing is beneficial in particular clinical settings. Identifying the etiology of FSGS guides selection of therapy and provides prognostic insight. Much progress has been made in our understanding of FSGS, but important outstanding issues remain, including the identity of the plasma factor believed to be responsible for primary FSGS, the value of routine implementation of genetic testing, and the identification of more effective and less toxic therapeutic interventions for FSGS.

Efficacy and Safety of Sparsentan Compared With Irbesartan in Patients With Primary Focal Segmental Glomerulosclerosis: Randomized, Controlled Trial Design (DUET)

Introduction

Primary focal segmental glomerulosclerosis (FSGS) is a leading cause of nephrotic syndrome and end-stage renal disease. There are no US Food and Drug Administration−approved therapies for FSGS, and treatment often fails to reduce proteinuria. Endothelin is an important factor in the pathophysiology of podocyte disorders, including FSGS. Sparsentan is a first-in-class, orally active, dual-acting angiotensin receptor blocker (ARB) and highly selective endothelin Type A receptor antagonist. This study is designed to evaluate whether sparsentan lowers proteinuria compared with an ARB alone and has a favorable safety profile in patients with FSGS.

Methods

DUET is a phase 2, randomized, active-control, dose-escalation study with an 8-week, fixed-dose, double-blind period followed by 136 weeks of open-label sparsentan treatment. Patients aged 8 to 75 years with primary FSGS will be randomized to treatment with sparsentan or irbesartan for 8 weeks.

Results

The primary efficacy objective is to test the hypothesis that sparsentan over the dose range (200 mg, 400 mg, or 800 mg daily) is superior to irbesartan (300 mg daily) in decreasing the urinary protein-to-creatinine ratio (UPC) from baseline to 8 weeks postrandomization. As secondary objectives, the trial will evaluate the proportion of patients who achieve prespecified targets of UPC reduction, changes in laboratory and quality-of-life indices, and detailed safety analysis. Analyses will be conducted at the end of the double-blind (week 8) and open-label (week 144) periods.

Discussion

This study will provide important evidence on whether dual ARB and endothelin blockade may be an effective therapeutic strategy for FSGS and may provide the rationale for next-phase trials.

Calcineurin Inhibitors in the Treatment of Primary Focal Segmental Glomerulosclerosis: A Systematic Review and Meta-analysis of the Literature

Purpose of review:

Primary focal segmental glomerulosclerosis (FSGS) is the most common cause of nephrotic syndrome in adults. Glucocorticoids have been evaluated in the treatment of primary FSGS in numerous retrospective studies. Evidence suggesting a role for including calcineurin inhibitors (CNIs) in early therapy remains limited. The aim of this study was to systematically review the literature examining the efficacy of CNIs in the treatment of primary FSGS both as first-line therapy and as an adjunctive agent in steroid-resistant patients, with respect to remission in proteinuria and renal survival.

Sources of information:

PubMed and EMBASE were searched from inception to August 2014 for prospective controlled trials, and case-control and cohort studies.

Findings:

After systematically applying our inclusion criteria, a total of 152 titles and abstracts were identified. Six randomized controlled trials and 2 cohort studies were reviewed. Three randomized controlled trials compared CNIs with placebo or supportive therapy. The pooled relative “risk” of proteinuria remission associated with cyclosporine was 7.0 (95% confidence interval, 2.9-16.8) compared with placebo/supportive therapy. There was very low heterogeneity among these studies with an I-squared of 0%. Three studies compared CNIs with another immunosuppressive agent. All prospective trials were conducted in patients with primary FSGS deemed steroid-resistant.

Limitations:

The relatively small number of included studies and their heterogeneity with respect to treatment protocols, and possible publication bias, limit conclusions drawn from this systematic review.

Implications:

The efficacy of CNIs has been evaluated in steroid-resistant primary FSGS patients. There is no evidence supporting their role as first-line therapy. Further studies are needed to determine this role.