Long-term outcomes of persistent disease and relapse in primary membranous nephropathy

Bucillamine-induced membranous nephropathy versus primary membranous nephropathy: comparing pathological features and kidney prognosis

To evaluate the pathological and clinical course differences between bucillamine‑induced membranous nephropathy (BCL-MN) and primary membranous nephropathy (p-MN). This retrospective cohort study included 29 BCL-MN patients and 98 p-MN patients at two hospitals from 2000 to 2019. We compared the kidney biopsy findings and clinical course between the BCL-MN and p-MN groups, focusing on pathological differences, proteinuria relapse rates, and 30% or greater decrease in the eGFR. While kidney function and proteinuria levels were similar, histopathological differences were observed. BCL-MN group showed less spike formation in LM and more stage I cases. IgG1 was predominant in BCL-MN group, contrasting with IgG4 in p-MN group. BCL-MN group had significantly higher prevalence of segmental subepithelial deposits (66.7% vs. 24.7%, p < 0.001) and para-mesangial deposits (61.5% vs. 18.1%, p < 0.001). Notably, foot process effacement in areas without dense deposits was more common in BCL-MN (96.3% vs. 4.6%, p < 0.001). Clinically, the majority of patients in the BCL-MN group experienced proteinuria resolution after 1 year of drug discontinuation alone, and there was no progression of renal function decline. BCL-MN differs from p-MN both histologically and clinically, which may be related to the mechanism induced by BCL.

A multicenter retrospective study on comparing the efficacy and safety of the therapy of intermittent cyclophosphamide and corticosteroids versus rituximab for primary membranous nephropathy

BACKGROUND

Few clinical studies compare the long-term remission, relapse, and safety of rituximab (RTX) or a combination of intermittent intravenous infusion of cyclophosphamide (CTX) and oral corticosteroid for primary membranous nephropathy (PMN) patients.

METHODS

We collected multicenter retrospective data on PMN patients with nephrotic syndrome who received RTX or intermittent intravenous CTX with oral corticosteroids between 1 January 2019 and 31 January 2024. Patients were followed up until two years after receiving immunotherapy. The primary outcomes were a composite of complete or partial remission rates at 6, 12, and 24 months. The secondary outcomes were the relapse and safety evaluation.

RESULTS

Forty patients treated with RTX and 27 with the CTX regime were available for analysis. No significant difference in the remission rate at 6, 12, or 24 months was observed between the two groups (p > .05). Kaplan-Meier's survival analysis showed that the relapse-free cumulative survival rate of the RTX group was superior to that of the CTX group (p = .023). Compared with baseline, both the media of urine protein and serum albumin levels in the two groups showed a significant improvement at 6 months and maintained through to the second year. No significant difference in the occurrence of total side effects between the two groups (p = .160).

CONCLUSIONS

There was no difference in remission rates and safety between RTX versus intermittent intravenous CTX combined with oral corticosteroid treatment for patients with PMN within 2 years. RTX appeared to have benefits in terms of prolonging relapse-free survival.

PLA2R Antibody Does Not Outperform Conventional Clinical Markers in Predicting Outcomes in Membranous Nephropathy

Introduction

The prognostic value of PLA2R antibody (Ab) test in clinical practice remains unclear. We aimed to evaluate its ability in predicting hard outcomes in primary membranous nephropathy (PMN) after adjustments to conventional markers of disease activity.

Methods

A total of 222 patients diagnosed with PMN from January 2003 to July 2019 having had a serum PLA2R Ab test, were included from 3 centers in the north of England. Baseline conventional markers, PLA2R-Ab-status (positive vs. negative), Ab-titer (high vs. low), and time of testing (pre-PLA2R era vs. PLA2R era) were evaluated for association with outcomes. Primary outcome was time to progression (composite of doubling of creatinine, stage 5 chronic kidney disease, or death). Secondary outcomes were time to partial remission (PR) and time to immunosuppression. Cox proportional hazard testing was used.

Results

During a median follow-up of 5.26 years, progression was seen in 65 (29.3%) and PR in 179 of 222 patients (80.6%). There was a clear association of estimated glomerular filtration rate (eGFR) (standardized hazard ratio [HRZ] = 0.767, P < 0.05) and urine protein-to-creatinine ratio (uPCR) (HRZ = 1.44, P < 0.005) with time to progression among all patients, and eGFR (HRZ = 0.606, P < 0.005) in Ab-positive patients. Baseline Ab-positivity was not associated with time to progression (adjusted hazard ratio [aHR] = 0.93, P = 0.71) or time to PR (aHR = 0.84, P = 0.13). Similarly, baseline high Ab-titer was not associated with time to progression (aHR = 1.07, P = 0.77) or time to PR (aHR = 0.794, P = 0.08).

Conclusion

Once adjusted to conventional markers of disease activity, baseline PLA2R Ab-positivity or Ab-titer do not predict disease progression or time to PR. Further studies are needed to harness the utility of PLA2R Ab test in prognostication in PMN.

Immunosuppressive therapy for progressive idiopathic membranous nephropathy: a cost-effectiveness analysis in China

BACKGROUND

This study aims to evaluate the cost-effectiveness of immunosuppressive therapy for patients with progressive idiopathic membranous nephropathy (IMN) from the Chinese healthcare system perspective.

METHODS

To estimate the cost-effectiveness of four regimens namely cyclophosphamide, cyclosporine, rituximab and tacrolimus-rituximab in treatment of IMN recommended by the updated Kidney Disease: Improving Global Outcomes (KDIGO) guideline 2021, a Markov model with five discrete states (active disease, remission, dialysis, kidney transplant and death) based on IMN patients aged 50 or above over a 30-years time horizon was constructed. Total costs were imputed from the Chinese healthcare system perspective, and health outcomes were converted into quality-adjusted life years (QALYs). The incremental cost-effectiveness ratio (ICER) was used to describe the results. The willingness-to-pay (WTP) threshold was set at $12,044 (China's 2021 Gross Domestic Product per capita). Sensitivity analyses were performed to test the uncertainties of the results.

RESULT

Compared with cyclophosphamide, both cyclosporine (incremental cost $28,337.09, incremental QALY-1.63) and tacrolimus-rituximab (incremental cost $28,324.13, incremental QALY -0.46) were considered at strictly dominated for their negative values in QALYs, and the ICER value of rituximab was positive (incremental cost $9,162.19, incremental QALY 0.44). Since the ICER of rituximab exceeds the pre-determined threshold, cyclophosphamide was likely to be the best choice for the treatment of IMN within the acceptable threshold range. The results of the sensitivity analysis revealed that the model outcome was mostly affected by the probability of remission in rituximab. In a probabilistic sensitivity analysis, cyclophosphamide had 62.4% probability of being cost-effective compared with other regimens when the WTP was $12,044 per QALY. When WTP exceeded $18,300, rituximab was more cost-effective than cyclophosphamide.

CONCLUSION

Compared with cyclosporine, rituximab and tacrolimus-rituximab, our model results indicated that cyclophosphamide represented the most cost-effective regimen for patients with progressive IMN in China.

Non-diabetic urine glucose in idiopathic membranous nephropathy

This study aims to analyze the characteristics of idiopathic membranous nephropathy (iMN) with nondiabetic urine glucose during the follow-up. We retrospectively analyzed the data of 1313 patients who were diagnosed iMN. The prevalence of nondiabetic urine glucose during follow-up was 10.89%. There were significant differences between the patients with nondiabetic urine glucose and those without urine glucose in gender, hypertension ratio, proteinuria, N-acetyl-β-glucosaminidase, retinol binding protein, serum albumin, serum creatinine (Scr), cholesterol, triglyceride and positive anti-phospholipase A2 receptor antibody ratio, glomerular sclerosis ratio, acute and chronic tubular injury lesion at baseline. To exclude the influence of the baseline proteinuria and Scr, case control sampling of urine glucose negative patients was applied according to gender, baseline proteinuria and Scr. The proteinuria nonremission (NR) ratio was 45.83 versus 12.50% of the urine glucose positive group and case control group. Partial remission (PR) ratio of the two groups was 36.46 versus 23.96% and complete remission (CR) ratio was 19.79% versus 63.54%, respectively. Patients with urine glucose had higher risk of 50% estimated glomerular filtration rate (eGFR) reduction. Cox regression showed that urine glucose and baseline Scr were risk factors of 50% reduction of eGFR. Urine glucose remission ratio of the patients with proteinuria NR, PR, and CR was 13.33, 56.25, and 94.73% (p < 0.005). Patients who got urine glucose remission also had better renal survival. In conclusion, non-diabetic urine glucose was closely related to proteinuria. It could be applied as a tubular injury marker to predict renal function.

A low rate of end-stage kidney disease in membranous nephropathy: A single centre study over 2 decades

INTRODUCTION

Membranous nephropathy is the commonest cause of nephrotic syndrome in non-diabetic Caucasian adults over the age of 40 years. Primary membranous nephropathy is limited to the kidneys. Clinical management aims to induce remission, either spontaneously with supportive care, or with immunosuppression. Here, we describe the natural history of this condition in a large tertiary centre in the UK.

METHODS

178 patients with primary membranous nephropathy were identified over 2 decades. We collected data on demographics, baseline laboratory values, treatment received and outcomes including progression to renal replacement therapy and death. Analysis was performed on the whole cohort and specific subgroups. Univariate and multivariate Cox regression was also performed.

RESULTS

Median age was 58.3 years with 63.5% male. Median baseline creatinine was 90μmol/L and urine protein-creatinine ratio 664g/mol. Remission (partial or complete) was achieved in 134 (75.3%), either spontaneous in 60 (33.7%) or after treatment with immunosuppression in 74 (41.6%), and of these 57 (42.5%) relapsed. Progression to renal replacement therapy was seen in 10.1% (much lower than classically reported) with mortality in 29.8%. Amongst the whole cohort, those who went into remission had improved outcomes compared to those who did not go into remission (less progression to renal replacement therapy [4.5% vs 28%] and death [20.1% vs 67%]. Those classified as high-risk (based on parameters including eGFR, proteinuria, serum albumin, PLA2R antibody level, rate of renal function decline) also had worse outcomes than those at low-risk (mortality seen in 52.6% vs 10.8%, p<0.001). The median follow-up period was 59.5 months.

CONCLUSION

We provide a comprehensive epidemiologic analysis of primary membranous nephropathy at a large tertiary UK centre. Only 10.1% progressed to renal replacement therapy. For novelty, the KDIGO risk classification was linked to outcomes, highlighting the utility of this classification system for identifying patients most likely to progress.

The evolution of the therapeutic approach to membranous nephropathy

Primary membranous nephropathy (MN) is a frequent cause of nephrotic syndrome (NS) in adults. In untreated patients, the outcome is variable, with one-third of the patients entering remission while the remaining ones show persisting proteinuria or progression to end-stage renal disease. Randomized clinical trials reported the efficacy of a 6-month regimen alternating intravenous and oral glucocorticoids with an alkylating agent every other month. The potential side effects of this regimen were limited by the fact that the use of glucocorticoids and alkylating agent did not exceed 3 months each. Two randomized trials with follow-ups (FU) up to 10 years provided assurance about the long-term efficacy and safety of this cyclical therapy. Calcineurin inhibitors have also been used successfully. However, in most responders, NS relapsed after the drug was withdrawn. Conflicting results have been reported with mycophenolate salts and adrenocorticotropic hormone. Observational studies reported good results with rituximab (RTX). Two controlled trials demonstrated the superiority of RTX over antiproteinuric therapy alone and cyclosporine. However, the FUs were relatively short and no randomized trial has been published against cyclical therapy. The available results, together with the discovery that most patients with MN have circulating antibodies against the phospholipase A2 receptor 1, support the use of cytotoxic drugs or RTX in MN. It is difficult to choose between these two different treatments. RTX is easier to use, but the FUs of the available studies are short, thus doubts remain about the long-term risk of relapses and the safety of repeated administrations of RTX.

Long-term renal survival and related risk factors for primary membranous nephropathy in Chinese children: a retrospective analysis of 217 cases

BACKGROUND

Primary membranous nephropathy (PMN) is a rare pathological finding in paediatric patients. Data on PMN in children have been restricted to studies with small samples and fairly short follow-up periods. Therefore, we conducted this single-centre study to evaluate the long-term renal survival and related risk factors for PMN in children, and the clinical and histological characteristics were also described.

METHOD

Two hundred and seventeen children with PMN were enrolled from July 2008 to September 2017. Patients with follow-up durations < 12 months were excluded, except for patients who progressed to end-stage kidney disease (ESKD) or experienced a related death within 12 months. Long-term renal survival and related risk factors were analysed.

RESULT

The sex ratio was 1.33:1 (male vs female), and the median age was 15.0 (14.0-17.0) years old. The most prominent clinical manifestation was nephrotic syndrome (130 59.9%), which was accompanied by various degrees of oedema (142 65.4%), hyperlipidaemia (151 69.6%), hypoalbuminemia (130 59.9%), and nephrotic proteinuria (135 62.2%). Hypertension occurred in 36.4% of children with PMN. After a median follow-up of 45.0 (23.5-74.0) months, 11 patients (5.1%) developed ESKD, and the cumulative kidney survival rates of ESKD at 5 and 10 years after renal biopsy were 95.3% and 67.8%, respectively. The cumulative kidney survival rates of the combined event of ESKD and/or 30% decline in estimated glomerular filtration rate (eGFR) at 5 and 10 years after renal biopsy were 92.6% and 59.5%, respectively. Cox multivariate regression and Kaplan-Meier analysis demonstrated that hypertension and proteinuria ≥ 50 mg/kg/day were associated with renal outcome.

CONCLUSION

In this study, the 5-year and 10-year cumulative renal survival rates of ESKD in children with PMN were reported for the first time as 95.3% and 67.8%, respectively. In addition, this is the first report to find that hypertension and proteinuria  ≥ 50 mg/kg/day are associated with renal outcome in children with PMN.

Efficacy of low or standard rituximab-based protocols and comparison to Ponticelli's regimen in membranous nephropathy

BACKGROUND

Patients (pts) with primary Membranous nephropathy (MN) have an autoimmune disease caused by autoantibodies against podocyte antigens and 60-80% of them have antibodies directed against the M-type phospholipase A2 receptor (PLA2R). Immunosuppressive treatment is recommended in high-medium risk pts. Recently the use of rituximab (RTX), has emerged as an important therapeutic option in pts with primary MN. The appropriate cumulative dose of RTX in PMN pts is still uncertain, and favorable outcomes even with low-dose of RTX has been described. We compared efficacy and safety of 3 different treatment regimens: low-dose RTX (Protocol 1, one dose of RTX 375 mg/m²), standard RTX protocol (Protocol 2, four weekly doses of rituximab 375 mg/m²) and Ponticelli's regimen.

METHODS

42 pts with primary MN and nephrotic syndrome were assigned to Protocol 1 (14 pts) or Protocol 2 (14 pts). All patients were followed for 24 months after RTX. Fourteen pts, matched for age and baseline serum creatinine (sCr) and proteinuria, treated with Ponticelli's regimen were examined as controls.

RESULTS

At 24 months, a significant improvement in proteinuria levels was observed in pts treated with Protocol 1 (7.5 ± 4.8 at T0; 0.21 ± 0.15 at T24, p < 0.01), Protocol 2 (5.1 ± 1.41 g/24 at T0; 0.35 ± 0.39 at T24 p < 0.01) and controls (8.27 ± 4.78 T0; 2.2 ± 1.9 g/24 h at T24, p < 0.01). No differences in clinical response (p = 0.53) was observed comparing the 3 groups.

CONCLUSIONS

Our data suggest that the RTX is a promising alternative to Ponticelli's regimen even at low-doses. This makes RTX a cost-effective treatment of primary MN in the short and medium terms.

Persistent Disease Activity in Patients With Long-Standing Glomerular Disease

INTRODUCTION

Glomerular diseases are characterized by variable disease activity over many years. We aimed to analyze the relationship between clinical disease activity and duration of glomerular disease.

METHODS

Disease activity in adults with chronic minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, and IgA nephropathy (IgAN; first diagnostic biopsy >5 years before enrollment; Of Longstanding Disease [OLD] cohort, n = 256) followed at Columbia University Medical Center (CUMC), was compared with disease activity of an internal and external cohort of patients with first diagnostic biopsy <5 years before enrollment drawn from the Cure Glomerulonephropathy Network (CureGN cohort, n = 1182; CUMC-CureGN cohort, n = 362). Disease activity was defined by (i) Kidney Disease: Improving Global Outcomes-recommended threshold criteria for initiation of immunosuppression in primary glomerulonephropathy (GN) and (ii) CureGN's Disease Activity Working Group definitions for activity.

RESULTS

No significant differences were detected among the 3 cohorts in terms of age, sex, serum creatinine, and urinary protein-to-creatinine ratio. For each GN subtype, disease activity in the OLD cohort was comparable with disease activity in the entire CureGN and the CUMC-CureGN cohort. When limiting our comparisons to disease activity in incident CUMC-CureGN patients (first diagnostic biopsy within 6 months of enrollment), OLD patients demonstrated similar activity rates as incident patients.

CONCLUSION

Disease activity did not differ among patients with shorter versus longer duration of disease. Such survivor patients, with long-term but persistent disease, are potentially highly informative for understanding the clinical course and pathogenesis of GN and may help identify factors mediating more chronic subtypes of disease.

Association of diabetes with failure to achieve complete remission of idiopathic membranous nephropathy

PURPOSE

The association of type 2 diabetes with proteinuria remission and renal function decline in patients with idiopathic membranous nephropathy (IMN) remains elusive. This study was designed to assess such association.

METHODS

In this retrospective cohort study, we included 656 IMN patients treated with immunosuppressants or plus corticosteroids, of whom 72 were diagnosed as type 2 diabetes prior to or at diagnosis of IMN. Data on age, sex, body mass index, presence of hypertension and diabetes, laboratory tests, and therapeutic regimens were retrospectively retrieved from medical record. Cox regression was used to analyze risks of failure to achieve remission, relapse, and developing a ≥ 30% decline in estimated glomerular filtration rate (eGFR) or end-stage renal disease (ESRD) associated with baseline diabetes.

RESULTS

The patients were followed for 36.6 (IQR 17.5-59.0) months, of whom 451 reached complete remission, 92 achieved partial remission, and 61 developed a ≥ 30% eGFR decline or ESRD. IMN relapse occurred in 30.6% of the 543 remitted patients. Baseline diabetes was associated with failure to achieve complete remission (HR 0.61, 95% CI 0.43-0.86, P = 0.005) in patients with IMN, independently of age, sex, hypertension, baseline serum albumin, urine protein levels, and eGFR, and therapeutic regimens. However, we failed to identify independent association between baseline diabetes and failure to achieve total remission (HR  0.85, 95% CI 0.63-1.1, P = 0.29), IMN relapse (OR 0.92, 95% CI 0.49-1.7, P = 0.80), or ≥ 30% decline in eGFR or ESRD (HR  1.4, 95% CI 0.78-2.7, P = 0.24) in patients with IMN.

CONCLUSIONS

Baseline diabetes may be independently associated with failure to achieve complete remission, but not with IMN relapse and renal function decline in IMN patients.

Rituximab versus steroids and cyclophosphamide for the treatment of primary membranous nephropathy: protocol of a pilot randomised controlled trial

INTRODUCTION

Primary membranous nephropathy (MN) is a common cause of nephrotic syndrome in adults. The disease may have different long-term outcomes. After 10 years of follow-up, 35%-50% of the untreated patients with persistent nephrotic syndrome may die or progress to end stage renal disease. The 2012 KDIGO (Kidney Disease Improving Global Outcomes) guidelines recommend that initial therapy should consist of alternating steroids and an alkylating agent for 6 months. Recent observational studies showed that the anti-CD20 antibody rituximab may be effective in inducing remission. We designed a pilot multicentre randomised trial to inform the design of a larger trial testing the efficacy and safety of treatment with steroids and cyclophosphamide versus rituximab in patients with primary MN and heavy proteinuria (>3.5 g/24 hours).

METHODS AND ANALYSIS

This pilot, open-label, two-parallel-arm, randomised clinical trial will enrol 70 patients with primary MN and heavy proteinuria. Patients will be randomised in a 1:1 ratio to either the intervention arm (rituximab) or the active comparator arm (corticosteroid/alkylating-agent therapy). The study will provide estimates of the probability of complete remission of proteinuria and risk of serious side effects at 12 months to inform the design of a larger trial. We will also assess the recruitment potential of each participating centre to address study feasibility.

ETHICS AND DISSEMINATION

The trial received ethics approval from the local ethics boards. We will publish pilot data to inform the design of a larger clinical trial.

TRIAL REGISTRATION NUMBERS

NCT03018535; 2011-006115-59.

The investigative burden of membranous nephropathy in the UK

Background

Membranous nephropathy (MN) represents two distinct disease entities. Primary MN is now recognized as an autoimmune condition associated with the anti-PLA₂R antibody and secondary MN occurs in tandem with malignancy, infection, drug therapy and other autoimmune conditions. Prior to the development of accessible enzyme-linked immunosorbent assays, the diagnosis of MN was one of exclusion. We studied whether the introduction of serum anti-PLA₂R antibody testing leads to a reduction in the frequency of investigations in MN patients.

Methods

Patients from three UK centres with a diagnosis of MN between 2009 and 2014 were identified. We compared patients who had a positive anti-PLA₂R test within 6 months of biopsy with those who had no test or a negative test. Records were reviewed for investigations that took place 6 months prior to and 6 months following the biopsy date to see if these were normal or identified a secondary cause of MN.

Results

In total, 184 patients were included: 80 had no test, 66 had a negative anti-PLA₂R test and 38 had a positive test within 6 months of diagnosis. In 2012, 46.5% of patients had an anti-PLA₂R test, increasing to 93.3% in 2014. From 2012 to 2014 the number of screening tests dropped from 10.03 to 4.29 and the costs from £497.92 to £132.94.

Conclusions

Since its introduction, a progressively higher proportion of patients diagnosed with MN had an anti-PLA₂R test. This has led to a reduction in the number of screening tests and in the cost of investigations carried out. The anti-PLA₂R test has the potential to reduce this burden as its use becomes more widespread.

Intravenous pulse cyclophosphamide and steroids induce immunological and clinical remission in New-incident and relapsing primary membranous nephropathy

AIM

Primary membranous nephropathy is associated with progression to end stage renal diseasein some patients. Standard therapy with cyclical cyclophosphamide and corticosteroids can be associated with significant adverse effects. We aimed to assess immunological and clinical response with intravenous pulse cyclophosphamide and oral steroids in patients with severe nephrotic syndrome - in a prospective observational cohort study.

METHODS

A total of 17 consecutive patients (nine new-incident and eight relapses) with severe nephrotic syndrome received monthly intravenous pulse cyclophosphamide and oral steroids after failure to achieve remission with supportive therapy. Immunosuppressive therapy was discontinued at 6 months or earlier if proteinuria regressed to <100 mg/mmol and patients were followed for 12 months. Achievement of partial remission was primary outcome; changes in clinical parameters and anti-PLA₂ R were secondary outcomes.

RESULTS

Dose of cyclophosphamide received was 5.4 g in New-incident patients and 4.2 g in patients with relapses. All 17 patients achieved partial remission within 6 months: proteinuria improved from 656 to 102 mg/mmol at 6 months and 55 mg/mmol at 12 months (P < 0.001); eGFR improved from 31 to 48 mL/min per 1.73 m² at 6 months and 45 mL/min per 1.73 m² at 12 months (P < 0.05). Anti-PLA₂ R levels reduced from 244 to 10 U/L at 6 months and 10 U/L at 12 months (P < 0.001). Two out of nine patients in the New-incident group developed subsequent relapse. Cumulative doses of cyclophosphamide and steroids that patients received was about half of the standard regime.

CONCLUSION

Pulse cyclophosphamide with oral steroids induced immunological and clinical partial remission at significantly reduced doses in primary membranous nephropathy.

Membranous Nephropathy and Anti-Podocytes Antibodies: Implications for the Diagnostic Workup and Disease Management

The discovery of circulating antibodies specific for native podocyte antigens has transformed the diagnostic workup and greatly improved management of idiopathic membranous nephropathy (iMN). In addition, their identification has clearly characterized iMN as a largely autoimmune disorder. Anti-PLA2R1 antibodies are detected in approximately 70% to 80% and anti-THSD7A antibodies in only 2% of adult patients with iMN. The presence of anti-THSD7A antibodies is associated with increased risk of malignancy. The assessment of PLA2R1 and THSD7A antigen expression in glomerular immune deposits has a better sensitivity than measurement of the corresponding autoantibodies. Therefore, in the presence of circulating anti-podocytes autoantibodies and/or enhanced expression of PLA2R1 and THSD7A antigens MN should be considered as primary MN (pMN). Anti-PLA2R1 or anti-THSD7A autoantibodies have been proposed as biomarkers of autoimmune disease activity and their blood levels should be regularly monitored in pMN to evaluate disease activity and predict outcomes. We propose a revised clinical workup flow for patients with MN that recommends assessment of kidney biopsy for PLA2R1 and THSD7A antigen expression, screening for circulating anti-podocytes antibodies, and assessment for secondary causes, especially cancer, in patients with THSD7A antibodies. Persistence of anti-podocyte antibodies for 6 months or their increase in association with nephrotic proteinuria should lead to the introduction of immunosuppressive therapies. Recent data have reported the efficacy and safety of new specific therapies targeting B cells (anti-CD20 antibodies, inhibitors of proteasome) in pMN which should lead to an update of currently outdated treatment guidelines.

[Membranous nephropathy in a Russian population]

AIM

To analyze the clinical and morphological manifestations of membranous nephropathy (MN) and to evaluate the efficiency of its therapy.

MATERIAL AND METHODS

MN cases in 2009 to 2016 were retrospectively detected with a subsequent analysis of patients with primary MN (PMN). The titer of IgG-autoantibodies to phospholipase A2 receptor (anti-PLA2R Ab) was determined by an indirect immunofluorescence assay. Treatment outcomes, such as the time course of changes in proteinuria, nephrotic syndrome (NS), and the development of complete and partial remissions (CR and PR), were assessed.

RESULTS

MN was detected in 201 cases; the secondary etiology of the disease was established in 24.9%. The prevalence of MN among morphologically confirmed glomerulopathies was 14%; that of PMN was 10.4%. The median period to diagnosis PMN was 8 (5; 19) months. 150 patients with PMN (66.7% were men; age was 50±15 years) were distributed according to the following morphological stages: Stages I (23.9%), II (48.5%), III (26.1%), and IV (1.5%). Elevated anti-PLA2R Ab levels were found in 51.6% of cases; NS in the presence of proteinuria was detected in 85.6% of patients. An estimated glomerular filtration rate (eGFR) of <60 ml/min/1.73 m2 was seen in 25% of cases. Treatment outcomes were evaluated in 80 cases; the median follow-up period was 19 (8; 40) months. 68% of cases had CR (32%) or PR (36%) with a median follow-up of 26 (13; 44) months. Spontaneous CRs or PRs were observed in 7.5% of the patients. Multivariate analysis showed that the probability of CR or PR increased 3.2-fold in the use of cyclophosphamide and/or cyclosporine and decreased as eGFR dropped.

CONCLUSION

In Russia, PMN is a common type of glomerulopathy, the specific features of which should include the low rates of spontaneous remissions and detection of anti-PLA2R Abs. For renal protection, the majority of patients with PMN require timely diagnosis and treatment; individualization of the choice of treatment and its enhanced efficiency call for further investigations.

Low-dose Rituximab therapy in resistant idiopathic membranous nephropathy: single-center experience

Background

Persistent significant proteinuria has been associated with increased risk of progression to end-stage kidney disease in patients with idiopathic membranous nephropathy (IMN). Rituximab (RTX) therapy has given encouraging results in IMN, but most of the studies have used a higher dose, which is limited by the high cost as well as a potential increased risk of infections. Our study aimed to assess the efficacy and safety of low-dose RTX in patients with immunosuppression-resistant IMN.

Methods

A total of 21 patients with treatment-resistant IMN treated with RTX from 2015 to 2016 at our center were included in the study. They received two doses of RTX (500 mg each) infusion 7 days apart. CD19 count was performed after 4 weeks. A single dose of RTX was repeated after 4–6 weeks if CD19 count was not depleted.

Results

The mean standard deviation age of patients was 33.3 ± 12.3 years and 33.3% were females. Mean proteinuria before RTX therapy was 6.2 ± 2.2 g/day, serum creatinine was 0.9 ± 0.3 mg/dL and estimated glomerular filtration rate (eGFR) was 95.8 ± 26.9 mL/min/1.73 m². All the patients were non-responders to prior immunosuppressive treatment. Twenty (95.2%) patients achieved targeted CD19 depletion with two doses of RTX. One patient required one additional RTX dose due to inadequate B-cell suppression. A total of 13 (61.9%) patients achieved remission with RTX therapy: 4 (19.0%) complete and 9 (42.9%) partial remission. Patients who did not respond to RTX had a significantly lower baseline eGFR compared with those who achieved remission (P = 0.022). One patient developed respiratory tract infection following RTX during the follow-up, which responded to a course of oral antibiotics. During median follow-up of 13.1 (10–23.9) months, four (19%) patients had deterioration in renal function and one patient relapsed after achieving partial remission. Renal survival was significantly better in patients who responded to RTX therapy as compared with those who did not achieve remission (P = 0.0037).

Conclusion

Low-dose RTX therapy is effective and safe in immunosuppression-resistant IMN.

Membranous nephropathy: thinking through the therapeutic options

Idiopathic membranous nephropathy (IMN) remains the most common cause of the nephrotic syndrome in adults and one of the leading identifiable causes of end-stage kidney disease. Prior to considering the best approach to treatment, three important components need to be considered. First, the natural history of the typical membranous patient today; second, the importance of identifying the causative factors; and third, the integration of the current data on the known autoantibody/antigen systems involved in IMN into the diagnosis and management of the patient. Combining this with information on the known indicators associated with a poor prognosis plus new data on surrogate markers that provide important clues that the treatment plan is correct has provided us with a more secure platform for choosing the right treatment for each patient. This already provides a more rational and precise approach to the use of our current therapeutic options. Even today, we can slow disease progression and in the future new approaches and new therapies are likely to lead to prevention of progression or even reversal of the injury in IMN, thereby leading to improved quality of life of our patients.

Comparison of prognostic, clinical, and renal histopathological characteristics of overlapping idiopathic membranous nephropathy and IgA nephropathy versus idiopathic membranous nephropathy

Overlapping idiopathic membranous nephropathy (IMN) and immunoglobulin A nephropathy (IgAN) is rare. This study aims to investigate the unique prognostic, clinical, and renal histopathological characteristics of IMN+IgAN. This retrospective observational study included 73 consecutive cases of IMN+IgAN and 425 cases of IMN treated between September 2006 and November 2015. Prognostic and baseline clinical and histopathological data were compared between the two patient groups. Poor prognostic events included a permanent 50% reduction in eGFR, end-stage renal disease, and all-cause mortality. Renal histopathology demonstrated that the patients with IMN+IgAN presented with significantly increased mesangial cell proliferation and matrix expansion, increased inflammatory cell infiltration, and higher proportions of arteriole hyalinosis and lesions than the patients with IMN (all P < 0.05). Kaplan–Meier analysis showed that the patients with IMN+IgAN had significantly higher cumulative incidence rates of partial or complete remission (PR or CR, P = 0.0085). Multivariate Cox model analysis revealed that old age at biopsy and high baseline serum creatinine and uric acid levels were significantly associated with poor prognosis (all P < 0.05), and increased IgA expression correlated significantly with PR or CR (P < 0.05). The present study found that overlapping IMN and IgAN presents with unique renal histopathology and appears not to cause a poorer prognosis than IMN.

A Proposal for a Serology-Based Approach to Membranous Nephropathy

Primary membranous nephropathy (MN) is an autoimmune disease mainly caused by autoantibodies against the recently discovered podocyte antigens: the M-type phospholipase A2 receptor 1 (PLA2R) and thrombospondin type 1 domain-containing 7A (THSD7A). Assays for quantitative assessment of anti-PLA2R antibodies are commercially available, but a semiquantitative test to detect anti-THSD7A antibodies has been only recently developed. The presence or absence of anti-PLA2R and anti-THSD7A antibodies adds important information to clinical and immunopathologic data in discriminating between primary and secondary MN. Levels of anti-PLA2R antibodies and possibly, anti-THSD7A antibodies tightly correlate with disease activity. Low baseline and decreasing anti-PLA2R antibody levels strongly predict spontaneous remission, thus favoring conservative therapy. Conversely, high baseline or increasing anti-PLA2R antibody levels associate with nephrotic syndrome and progressive loss of kidney function, thereby encouraging prompt initiation of immunosuppressive therapy. Serum anti-PLA2R antibody profiles reliably predict response to therapy, and levels at completion of therapy may forecast long-term outcome. Re-emergence of or increase in antibody titers precedes a clinical relapse. Persistence or reappearance of anti-PLA2R antibodies after kidney transplant predicts development of recurrent disease. We propose that an individualized serology-based approach to MN, used to complement and refine the traditional proteinuria-driven approach, will improve the outcome in this disease.

Membranous nephropathy: integrating basic science into improved clinical management

Idiopathic membranous nephropathy (INM) remains a common cause of the nephrotic syndrome in adults. The autoimmune nature of IMN was clearly delineated in 2009 with the identification of the glomerular-deposited IgG to be a podocyte receptor, phospholipase A2 receptor (PLA2R) in 70% to 75% of cases. This anti-PLA2R autoantibody, predominantly the IgG4 subclass, has been quantitated in serum using an enzyme-linked immunosorbent assay and has been used to aid diagnosis and monitor response to immunosuppressive therapy. In 2014, a second autoantigen, thrombospondin type 1 domain-containing 7A (THSD7A), was identified. Immunostaining of biopsy specimens has further detected either PLA2R or THSD7A antigen in the deposited immune complexes in 5% to 10% of cases autoantibody seronegative at the time of biopsy. Therefore, the term IMN should now be superseded by the term primary or autoimmune MN (AMN) (anti-PLA2R or anti-THSD7A positive) classifying ∼80% to 90% of cases previously designated IMN. Cases of secondary MN associated with other diseases show much lower association with these autoantibodies, but their true incidence in secondary cases still needs to be defined. How knowledge of the autoimmune mechanism and the sequential measurement of these autoantibodies is likely to change the clinical management and trajectory of AMN by more precisely defining its diagnosis, prognosis, and treatment is discussed. Their application early in the disease course to new and old therapies will provide additional precision to AMN management. We also review innovative therapeutic approaches on the horizon that are expected to lead to our ultimate goal of improved patient care in A(I)MN.