High-Dose Rituximab and Early Remission in PLA2R1-Related Membranous Nephropathy

Fibrinogen-albumin ratio predicts treatment response in phospholipase A2 receptor-associated membranous nephropathy with nephrotic syndrome

BACKGROUND

The M-type phospholipase A2 receptor (PLA2R)-associated primary membranous nephropathy (PMN) is an immune-related disease in adults with increasing morbidity and variable treatment response, in which inflammation may contribute to the multifactorial immunopathogenesis. The relationship between fibrinogen-albumin ratio (FAR), serving as a novel inflammatory biomarker, and PMN is still unclear. Therefore, this study aims to clarify the association between FAR and disease activity and therapy response of PMN.

METHODS

110 biopsy-proven phospholipase A2 receptor (PLA2R) -associated PMN participants with nephrotic syndrome from January 2017 to December 2021 were recruited in the First Affiliated Hospital of Nanjing Medical University. The independent risk factors of non-remission (NR) and the predictive ability of FAR were explored by Cox regression and receiver-operating characteristic (ROC) curve analysis. According to the optimal cutoff value, study patients were categorized into the low-FAR group (≤the cutoff value) and the high-FAR group (>the cutoff value). Spearman's correlations were used to examine the associations between FAR and baseline clinicopathological characteristics. Kaplan-Meier method was used to assess the effects of FAR on remission.

RESULTS

In the entire study cohort, 78 (70.9%) patients reached complete or partial remission (CR or PR). The optimal cutoff value of FAR for predicting the remission outcome (CR + PR) was 0.233. The Kaplan-Meier survival analysis demonstrated that the high-FAR group (>0.233) had a significantly lower probability to achieve CR or PR compared to the low-FAR group (≤0.233) (Log Rank test, p = 0.021). Higher levels of FAR were identified as an independent risk factor for NR, and the high-FAR group was associated with a 2.27 times higher likelihood of NR than the low-FAR group (HR 2.27, 95% CI 1.01, 5.13, p = 0.048). These relationships remained robust with further analysis among calcineurin inhibitors (CNIs)-receivers. In the multivariate Cox regression model, the incidence of NR was 4.00 times higher in the high-FAR group than in the low-FAR group (HR 4.00, 95% CI 1.41, 11.31, p = 0.009). Moreover, ROC analysis revealed the predictive value of FAR for CR or PR with a 0.738 area under curve (AUC), and the AUC of anti-PLA2R Ab was 0.675. When combining FAR and anti-PLA2R Ab, the AUC was boosted to 0.766.

CONCLUSIONS

FAR was significantly correlated with proteinuria and anti-PLA2R Ab in PMN. As an independent risk factor for NR, FAR might serve as a potential inflammation-based prognostic tool for identifying cases with poor treatment response, and the best predictive cutoff value for outcomes was 0.233.

Efficacy and safety of Mahuang Fuzi and Shenzhuo Decoction for treatment of primary membranous nephropathy: a multicenter prospective trial

BACKGROUND

This study aims to undertake a comprehensive assessment of the effectiveness and safety profile of Mahuang Fuzi and Shenzhuo Decoction (MFSD) in the management of primary membranous nephropathy (PMN), within the context of a prospective clinical investigation.

METHODS

A multicenter, open-label clinical trial was executed on patients diagnosed with PMN. These individuals were subjected to MFSD therapy for a duration of at least 24 months, with primary outcome of clinical remission rates. The Cox regression analysis was employed to discern the pertinent risk factors exerting influence on the efficacy of MFSD treatment, with scrupulous monitoring of any adverse events.

RESULTS

The study comprised 198 participants in total. Following 24 months of treatment, the remission rate was 58.6% (116/198). Among the subgroup of 130 participants subjected to a 36-month follow-up, the remission rate reached 70% (91/130). Subgroup analysis revealed that neither a history of immunosuppressive therapy (HIST) nor an age threshold of ≥60 years exhibited a statistically significant impact on the remission rate at the 24-month mark (p > .05). Multivariate Cox regression analyses elucidated HIST, nephrotic syndrome, or mass proteinuria, and a high-risk classification as noteworthy risk factors in the context of MFSD treatment. Remarkably, no fatalities resulting from side effects were documented throughout the study's duration.

CONCLUSIONS

This trial establishes the efficacy of MFSD as a treatment modality for membranous nephropathy. MFSD demonstrates a favorable side effect profile, and remission rates are consistent across patients, irrespective of HIST and age categories.

Predictive value of the domain specific PLA2R antibodies for clinical remission in patients with primary membranous nephropathy: A retrospective study

BACKGROUND

M-type phospholipase A2 receptor (PLA2R) is a major auto-antigen of primary membranous nephropathy(PMN). Anti-PLA2R antibody levels are closely associated with disease severity and therapeutic effectiveness. Analysis of PLA2R antigen epitope reactivity may have a greater predictive value for remission compared with total PLA2R-antibody level. This study aims to elucidate the relationship between domain-specific antibody levels and clinical outcomes of PMN.

METHODS

This retrospective analysis included 87 patients with PLA2R-associated PMN. Among them, 40 and 47 were treated with rituximab (RTX) and cyclophosphamide (CTX) regimen, respectively. The quantitative detection of -immunoglobulin G (IgG)/-IgG4 targeting PLA2R and its epitope levels in the serum of patients with PMN were obtained through time-resolved fluorescence immunoassays and served as biomarkers in evaluating the treatment effectiveness. A predictive PMN remission possibility nomogram was developed using multivariate logistic regression analysis. Discrimination in the prediction model was assessed using the area under the receiver operating characteristic curve (AUC-ROC).Bootstrap ROC was used to evaluate the performance of the prediction model.

RESULTS

After a 6-month treatment period, the remission rates of proteinuria, including complete remission and partial remission in the RTX and CTX groups, were 70% and 70.21% (P = 0.983), respectively. However, there was a significant difference in immunological remission in the PLA2R-IgG4 between the RTX and CTX groups (21.43% vs. 61.90%, P = 0.019). Furthermore, we found differences in PLA2R-CysR-IgG4(P = 0.030), PLA2R-CTLD1-IgG4(P = 0.005), PLA2R-CTLD678-IgG4(P = 0.003), and epitope spreading (P = 0.023) between responders and non-responders in the CTX group. Multivariate logistic analysis showed that higher levels of urinary protein (odds ratio [OR], 0.49; 95% confidence interval [CI], 0.26-0.95; P = 0.035) and higher levels of PLA2R-CTLD1-IgG4 (OR, 0.79; 95%CI,0.62-0.99; P = 0.041) were independent risk factors for early remission. A multivariate model for estimating the possibility of early remission in patients with PMN is presented as a nomogram. The AUC-ROC of our model was 0.721 (95%CI, 0.601-0.840), in consistency with the results obtained with internal validation, for which the AUC-ROC was 0.711 (95%CI, 0.587-0.824), thus, demonstrating robustness.

CONCLUSIONS

Cyclophosphamide can induce immunological remission earlier than rituximab at the span of 6 months. The PLA2R-CTLD1-IgG4 has a better predict value than total PLA2R-IgG for remission of proteinuria at the 6th month.

Optimized rituximab regimen versus recommended regimen for idiopathic membranous nephropathy: A single-center retrospective cohort study

BACKGROUND

Rituximab (RTX) has become the first-line treatment for idiopathic membranous nephropathy (IMN). Compared with conventional therapy, rituximab therapy has a more favorable safety profile. However, the recommended RTX dose as a flux may have its limitations. The aim of this study was to investigate the clinical efficacy and safety of three regimens, including a cyclic corticosteroid-cyclophosphamide regimen and two different doses of RTX regimens, for the treatment of IMN.

METHODS

We recruited 58 patients with IMN confirmed by renal biopsy. 20 patients were treated with a cycle regimen, 22 patients were received RTX with 500 mg per week, totaling a dose of 2000 mg (optimized RTX group), and 16 patients received RTX with 1000 mg at day 1 and day 15 (recommended RTX group). Treatment responses, including complete remission (CR) and partial remission (PR), and outcome adverse events such as steroid diabetes, infections and a drop in white blood cell count, were compared among the three groups after 9 months of follow-up.

RESULTS

At 9-month follow-up, the composite remission rates (CR + PR) were 90 %, 72.7 %, and 75 % for the cycle regimen group, optimized RTX group, and recommended RTX group, respectively, with CR of 35 %, 22.7 %, and 25 %, respectively. There was no statistical difference between the three groups on CR and composite remission. Kaplan-Meier survival analyses showed no significant differences in cumulative CR rates and cumulative composite remission rates among the three groups (P = 0.632, P = 0.258). The cycle regimen group had a higher risk of steroid diabetes (35 %). Compared with the recommended RTX regimen, the optimized regimen reduced the incidence of adverse events of infection (9.1 % vs. 37.5 %, P = 0.049), especially in patients older than 60 years of age (P = 0.026). A lower anti-PLA2R at baseline may be associated with a higher risk of infection (P = 0.043).

CONCLUSIONS

The efficiency of low-dose and long-course of RTX regiment is not inferior to the recommended treatment regimen, and this regimen can effectively reduce the incidence of infection in patients with IMN. Moreover, we recommend a low-dose, long course of RTX treatment for the elderly.

Dosing optimization of rituximab for primary membranous nephropathy by population pharmacokinetic and pharmacodynamic study

Primary membranous nephropathy (PMN) is the most common cause for adult nephrotic syndrome. Rituximab has demonstrated promising clinical efficacy by random controlled trials and the off-label use is widely adopted in PMN. However, the standard dosage is borrowed from B cell lymphoma treatment with far more antigens and is oversaturated for PMN treatment, accompanied with additional safety risk and unnecessary medical cost. More than 15% serious adverse events were observed under standard dosage and low dose therapies were explored recently. Dose optimization by clinical trials is extremely time- and cost-consuming and can be significantly accelerated with the aid of model-informed drug development. Here, we aim to establish the first population pharmacokinetic and pharmacodynamic (PPK/PD) model for rituximab in PMN to guide its dosage optimization. Rituximab pharmacokinetic and pharmacodynamic data from 41 PMN patients in a retrospective study under a newly proposed monthly mini-dose were used to construct quantitative dose-exposure-response relationship via mechanistic target-mediated drug disposition (TMDD) model followed by regression between the reduction of anti-PLA2R titer and time after the treatment. The final model, validated by goodness-of-fit plots, visual predictive checks and bootstrap, was used to recommend the optimized dosing regimen by simulations. The model was well validated for PK/PD prediction. The systemic clearance and half-life are 0.54 L/h and 14.7 days, respectively. Simulation of a novel regimen (6 monthly doses of 100 mg) indicated the comparable ability and superior duration time of CD20+ B cell depletion compared with standard dosage, while the cumulative dosage and safety risk was significantly decreased. We established the first PPK/PD model and provide evidence to support the dosage optimization based on monthly mini-dose. Our study can also efficiently accelerate dosage optimization of novel anti-CD20 antibodies in PMN and other indications.

Understanding the podocyte immune responses in proteinuric kidney diseases: from pathogenesis to therapy

The glomerular filtration barrier, comprising the inner layer of capillary fenestrated endothelial cells, outermost podocytes, and the glomerular basement membrane between them, plays a pivotal role in kidney function. Podocytes, terminally differentiated epithelial cells, are challenging to regenerate once injured. They are essential for maintaining the integrity of the glomerular filtration barrier. Damage to podocytes, resulting from intrinsic or extrinsic factors, leads to proteinuria in the early stages and eventually progresses to chronic kidney disease (CKD). Immune-mediated podocyte injury is a primary pathogenic mechanism in proteinuric glomerular diseases, including minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, and lupus nephritis with podocyte involvement. An extensive body of evidence indicates that podocytes not only contribute significantly to the maintenance of the glomerular filtration barrier and serve as targets of immune responses but also exhibit immune cell-like characteristics, participating in both innate and adaptive immunity. They play a pivotal role in mediating glomerular injury and represent potential therapeutic targets for CKD. This review aims to systematically elucidate the mechanisms of podocyte immune injury in various podocyte lesions and provide an overview of recent advances in podocyte immunotherapy. It offers valuable insights for a deeper understanding of the role of podocytes in proteinuric glomerular diseases, and the identification of new therapeutic targets, and has significant implications for the future clinical diagnosis and treatment of podocyte-related disorders.

Comparative pharmacoeconomic analysis of rituximab and traditional tacrolimus regimens in membranous nephropathy in China

Background: Rituximab (RTX) is a monoclonal antibody that selectively targets CD20 and is frequently used in the treatment of membranous nephropathy (MN). Analysis of the therapeutic efficacy and safety of RTX in treating MN in practice and a comparative pharmacoeconomic analysis of the RTX and traditional tacrolimus (TAC) regimens can provide valuable insights to aid decision-making by the government and relevant medical insurance departments. Methods: We conducted a statistical analysis of medical records from patients diagnosed with MN who underwent RTX treatment between 1 January 2019 and 1 January 2023. The TAC data were obtained from the clinical literature. The efficacy rates and incidence of adverse effects (AEs) were calculated to compare the efficacy and safety of RTX and TAC. Based on the patient's disease status, we developed a Markov model to compare the total cost, remission rate, and incremental cost-effectiveness ratio (ICER) of the two regimens. Both univariate and probability sensitivity analyses were performed to validate the stability of the developed model. Results: The RTX group enrolled 53 patients with MN, and the 12-month overall efficacy rate was not significantly different from that of the TAC group with 35 patients (86.79% vs. 71.4%, p = 0.0131); however, the relapse rate was significantly lower in the RTX group (3.77% vs. 22.8%, p = 0.016). The RTX group demonstrated no severe AEs (SAEs), while the TAC group demonstrated six cases of SAEs, including 4 cases of severe pneumonia, 1 case of lung abscess and 1 case of interstitial lung disease, accounting for 7.89% of traditional tacrolimus-treated patients. The baseline analysis results revealed that over a 5-year post-treatment period, RTX increased quality-adjusted life years (QALYs) by 0.058 and costs by ¥7,341. Assuming three times the 2022 domestic gross domestic product as the willingness-to-pay (WTP) threshold per QALY, the ICER of RTX compared to TAC was ¥124,631.14/QALY, which is less than the WTP threshold of ¥257,094/QALY, indicating that RTX treatment is approximately two times more cost-effective compared to TAC. Conclusion: The current analysis indicates that despite the expensive unit price of RTX, it remains a cost-effective treatment option for MN compared to TAC.

Optimization of Rituximab Therapy in Adult Patients With PLA2R1-Associated Membranous Nephropathy With Artificial Intelligence

Introduction

Rituximab is a first-line treatment for membranous nephropathy. Nephrotic syndrome limits rituximab exposure due to urinary drug loss. Rituximab underdosing (serum level <2 μg/ml at month-3) is a risk factor for treatment failure. We developed a machine learning algorithm to predict the risk of underdosing based on patients' characteristics at rituximab infusion. We investigated the relationship between the predicted risk of underdosing and the cumulative dose of rituximab required to achieve remission.

Methods

Rituximab concentrations were measured at month-3 in 92 sera from adult patients with primary membranous nephropathy, split into a training (75%) and a testing set (25%). A forward-backward machine-learning procedure determined the best combination of variables to predict rituximab underdosing in the training data set, which was tested in the test set. The performances were evaluated for accuracy, sensitivity, and specificity in 10-fold cross-validation training and test sets.

Results

The best variables combination to predict rituximab underdosing included age, gender, body surface area (BSA), anti-phospholipase A2 receptor type 1 (anti-PLA2R1) antibody titer on day-0, serum albumin on day-0 and day-15, and serum creatinine on day-0 and day-15. The accuracy, sensitivity, and specificity were respectively 79.4%, 78.7%, and 81.0% (training data set), and 79.2%, 84.6% and 72.7% (testing data set). In both sets, the algorithm performed significantly better than chance (P < 0.05). Patients with an initial high probability of underdosing experienced a longer time to remission with higher rituximab cumulative doses required to achieved remission.

Conclusion

This algorithm could allow for early intensification of rituximab regimen in patients at high estimated risk of underdosing to increase the likelihood of remission.

Therapeutic drug monitoring in childhood idiopathic nephrotic syndrome: a state of the art review

Immunosuppressants are commonly used as steroid-sparing agents in childhood idiopathic nephrotic syndrome (NS) to induce and sustain remissions. These drugs have narrow therapeutic indices with high inter- and intra-patient variability. Therapeutic drug monitoring (TDM) would therefore be essential to guide the prescription. Multiple factors in NS contribute to additional variability in drug concentrations, especially during relapses. In this article, we review the currently available evidence of TDM in NS and suggest a practical approach for clinicians' reference.

Sirtuin 6 protects against podocyte injury by blocking the renin-angiotensin system by inhibiting the Wnt1/β-catenin pathway

Sirtuins (Sirts) are a family of nicotinamide adenine dinucleotide-dependent protein deacetylases that share diverse cellular functions. Increasing evidence shows that Sirts play a critical role in podocyte injury, which is a major determinant of proteinuria-associated renal disease. Membranous nephropathy (MN) is a typical glomerular disease in which podocyte damage mediates proteinuria development. In this study we investigated the molecular mechanisms underlying the regulatory roles of Sirt in podocyte injury in MN patients, rats with cationic bovine serum albumin (CBSA)-induced MN and zymosan activation serum (ZAS)-stimulated podocytes. Compared with healthy controls, MN patients showed significant reduction in intrarenal Sirt1 and Sirt6 protein expression. In CBSA-induced MN rats, significant reduction in intrarenal Sirt1, Sirt3 and Sirt6 protein expression was observed. However, only significant decrease in Sirt6 protein expression was found in ZAS-stimulated podocytes. MN patients showed significantly upregulated protein expression of Wnt1 and β-catenin and renin-angiotensin system (RAS) components in glomeruli. CBSA-induced MN rats exhibited significantly upregulated protein expression of intrarenal Wnt1 and β-catenin and their downstream gene products as well as RAS components. Similar results were observed in ZAS-stimulated podocytes. In ZAS-stimulated podocytes, treatment with a specific Sirt6 activator UBCS039 preserved the protein expression of podocin, nephrin and podocalyxin, accompanied by significant inhibition of the protein expression of β-catenin and its downstream gene products, including Snail1 and Twist; treatment with a β-catenin inhibitor ICG-001 significantly preserved the expression of podocyte-specific proteins and inhibited the upregulation of downstream β-catenin gene products accompanied by significant suppression of the protein expression of RAS components. Thus, we demonstrate that Sirt6 ameliorates podocyte injury by blocking RAS signalling via the Wnt1/β-catenin pathway. Sirt6 is a specific therapeutic target for the treatment of podocyte damage-associated renal disease.

How to Choose the Right Treatment for Membranous Nephropathy

Membranous nephropathy is an autoimmune disease affecting the glomeruli and is one of the most common causes of nephrotic syndrome. In the absence of any therapy, 35% of patients develop end-stage renal disease. The discovery of autoantibodies such as phospholipase A2 receptor 1, antithrombospondin and neural epidermal growth factor-like 1 protein has greatly helped us to understand the pathogenesis and enable the diagnosis of this disease and to guide its treatment. Depending on the complications of nephrotic syndrome, patients with this disease receive supportive treatment with diuretics, ACE inhibitors or angiotensin-receptor blockers, lipid-lowering agents and anticoagulants. After assessing the risk of progression of end-stage renal disease, patients receive immunosuppressive therapy with various drugs such as cyclophosphamide, steroids, calcineurin inhibitors or rituximab. Since immunosuppressive drugs can cause life-threatening side effects and up to 30% of patients do not respond to therapy, new therapeutic approaches with drugs such as adrenocorticotropic hormone, belimumab, anti-plasma cell antibodies or complement-guided drugs are currently being tested. However, special attention needs to be paid to the choice of therapy in secondary forms or in specific clinical contexts such as membranous disease in children, pregnant women and patients undergoing kidney transplantation.

Development and External Validation of a Nomogram for Predicting the Effect of RTX on the Treatment of Membranous Nephropathy

Introduction

Rituximab (RTX) has been shown to be effective in inducing immunological remission in patients with membranous nephropathy (MN). Some patients required more than one course of RTX to achieve immunological remission. Identifying patients who need more courses of RTX to achieve immunological remission is beneficial for better physician-patient communication, the assessment of treatment course, and the evaluation of medical costs. This study aims to establish a practical model to predict the probability of immunological remission after receiving one cycle of RTX.

Methods

This study enrolled 106 patients from the First Affiliated Hospital of Zhengzhou University in the modeling group and 30 patients from Henan Provincial Hospital of Traditional Chinese Medicine in the external validation group. Patients in the modeling group were divided into responders or nonresponders according to whether they achieved immunological remission or not after following up for 6 months. A nomogram was established based on the results of logistic regression analysis. The predictive performance of the nomogram was evaluated by the area under the receiver operating characteristic curve (AUC), calibration curves, and decision curve analysis (DCAs).

Results

In the modeling group, 75 (70.8%) patients achieved immunological remission within 6 months after receiving one cycle of RTX. Significant differences were observed between nonresponders and responders. Risk factors used in nomogram included PLA2R antibody, hemoglobin, and gender. The AUC value of nomogram was 0.797 (95% CI 0.701-0.894, P<0.001). The calibration curves demonstrated acceptable agreement between the predicted outcomes by the nomogram and the actual values. DCA curves showed good positive net benefits in the predictive model. The external validation also demonstrated the reliability of the prediction nomogram.

Conclusion

A predictive nomogram including PLA2R antibody, hemoglobin, and gender may provide a basis to predict the doses of RTX needed in MN patients.

Oxidative stress and inflammation are mediated via aryl hydrocarbon receptor signalling in idiopathic membranous nephropathy

Membranous nephropathy (MN) patients are diagnosed by the presence of phospholipase A2 receptor (PLA2R) before they progress to renal failure. However, the subepithelium-like immunocomplex deposit-mediated downstream molecular pathways are poorly understood. The aryl hydrocarbon receptor (AHR), NF-ƙB and Nrf2 pathways play central roles in the pathogenesis and progression of chronic kidney disease. However, their mutual effects on MN require further examination. Thus, we investigated the effect of AHR signalling on the NF-ƙB and Nrf2 pathways in IMN patients, cationic bovine serum albumin (CBSA)-injected rats and zymosan activation serum (ZAS)-treated podocytes. IMN patients show significantly decreased serum total protein and albumin levels, increased urine protein levels and intrarenal IgG4 and PLA2R protein expression in glomeruli compared with controls. IMN patients exhibited increased mRNA expression of intrarenal AHR and its target genes, including CYP1A1, CYP1A2, CYP1B1 and COX-2. This increase was accompanied by significantly upregulated protein expression of CD3, NF-ƙB p65 and COX-2 and significantly downregulated Nrf2 and HO-1 expression. Similarly, CBSA-induced rats showed severe proteinuria and activated intrarenal AHR signalling. This was accompanied by significantly upregulated protein expression of intrarenal p-IκBα, NF-κB p65 and its gene products, including COX-2, MCP-1, iNOS, 12-LOX, p47phox and p67phox, and significantly downregulated protein expression of Nrf2 and its gene products, including HO-1, catalase, GCLC, GCLM, MnSOD and NQO1. These results were further verified in ZAS-induced podocytes. Treatment with the AHR antagonist CH223191 and AHRsiRNA significantly preserved podocyte-specific protein expression and improved the NF-ƙB and Nrf2 pathways in ZAS-induced podocytes. In contrast, similar results were obtained in ZAS-induced podocytes treated with the NF-ƙB inhibitor BAY 11-7082 and NF-κBp65 siRNA. However, neither method had a significant effect on AHR signalling. Collectively, these results indicate that the NF-ƙB pathway is a downstream target of AHR signalling. Our findings suggest that blocking AHR signalling inhibits oxidative stress and inflammation, thereby improving proteinuria and renal injury.

The place of cyclical therapy for the treatment of membranous nephropathy in the era of rituximab

Primary membranous nephropathy (MN) is the most frequent cause of nephrotic syndrome in adults, due to a variety of autoantibodies, most frequently against phospholipase A2 receptor (PLA2R). In severe cases or when spontaneous remission is not achieved, immunosuppression is required. Cyclical therapy, based on glucocorticoids and cyclophosphamide on alternate months for 6 months, has proven effective to induce remission and reduce the risk of end-stage renal disease. Since the early 2000s, rituximab (RTX) has emerged as a key player in the management of MN, showing overall comparable effectiveness and likely better safety compared with the cyclical regimen, despite the lack of adequately powered trials comparing the two approaches head to head. For these reasons, RTX is now considered the agent of choice for most patients with MN. However, there are still uncertainties. Around 20-40% of patients are resistant to RTX, especially in the setting of high anti-PLA2R levels, and this drug remains relatively unexplored in patients with the most severe disease. In these scenarios, although the expanding therapeutic armamentarium is probably going to provide further options, the cyclical regimen still plays a key role as a safety net. The aim of this article is to illustrate the role of cyclical therapy in the RTX era.

Monthly mini-dose rituximab for primary anti-PLA2R-positive membranous nephropathy: a personalized approach

BACKGROUND

The currently recommended dose of rituximab for primary membranous nephropathy is as high as that for lymphoma. However, the clinical manifestations of membranous nephropathy vary widely. Therefore, achieving individualized treatment is a topic that needs to be explored. This study assessed the efficacy of monthly mini-dose rituximab monotherapy in patients with primary membranous nephropathy.

METHODS

This retrospective study included 32 patients with primary membranous nephropathy treated at Peking University Third Hospital between March 2019 and January 2023. All patients were anti-phospholipase A2 receptor (PLA2R) antibody-positive and received rituximab 100 mg intravenously monthly for at least 3 months without other immunosuppressive therapy. Rituximab infusions were sustained until either remission of the nephrotic syndrome or a minimum serum anti-PLA2R titer ˂ 2 RU/mL was achieved.

RESULTS

The baseline parameters included: proteinuria, 8.5 ± 3.6 g/day; serum albumin, 24.8 ± 3.4 g/L; and anti-PLA2R antibody, 160 (20-2659) RU/mL. B-cell depletion was achieved in 87.5% patients after the first dose of rituximab 100 mg and in 100% after the second equivalent dose. The median follow-up was 24 months (range 18-38). Twenty-seven (84%) patients achieved remission, with 11 (34%) patients achieving complete remission by last follow-up. The relapse-free survival from the last infusion was 13.5 months (range 3-27). Patients were stratified into the low-titer (< 150 RU/mL, n = 17) and high-titer groups (≥ 150 RU/mL, n = 15) based on the anti-PLA2R titer. Sex, age, urinary proteins, serum albumin, and estimated glomerular filtration rate at baseline did not differ significantly between the two groups. At 18 months, compared to the low-titer group, the rituximab dose (960 ± 387 vs 694 ± 270 mg, p = 0.030) was higher, while serum albumin (37.0 ± 5.4 vs 41.3 ± 5.4 g/L, p = 0.033) and the complete remission rate (13% vs 53%, p = 0.000) were both lower in the high-titer group.

CONCLUSIONS

Monthly rituximab 100 mg appeared as a potential effective regimen for treating anti-PLA2R-associated primary membranous nephropathy with a low anti-PLA2R titer. The lower the anti-PLA2R titer, the lower the rituximab dose required to achieve remission.

TRIAL REGISTRATION

A retrospective study, registered at ChiCTR (ChiCTR2200057381) on March 10, 2022.

Update on the Application of Monoclonal Antibody Therapy in Primary Membranous Nephropathy

When first introduced, rituximab (RTX), a chimeric anti-CD20 monoclonal antibody, brought about an alternative therapeutic paradigm for primary membranous nephropathy (PMN). Rituximab was shown to be effective and safe in PMN patients with kidney dysfunction, with. patients receiving second-line rituximab therapy achieving remission as effectively as those patients who had not previously received immunotherapy. No safety issues were reported. The B cell-driven protocol seems to be as efficient as the 375 mg/m² × 4 regimen or 1 g × 2 regimen in achieving B cell depletion and remission, but patients with high M-type phospholipase A2 receptor (PLA2R) antibody levels may benefit from a higher dose of rituximab. While rituximab added another therapeutic option to the treatment regimen, it does have limitations as 20 to 40% of patients do not respond. Not all patients respond to RTX therapy for lymphoproliferative disorders either, therefore further novel anti-CD20 monoclonal antibodies have been developed and these may provide alternative therapeutic options for PMN. Ofatumumab, a fully human monoclonal antibody, specifically recognizes an epitope encompassing both the small and large extracellular loops of the CD20 molecule, resulting in increased complement-dependent cytotoxic activity. Ocrelizumab binds an alternative but overlapping epitope region to rituximab and displays enhanced antibody-dependent cellular cytotoxic (ADCC) activities. Obinutuzumab is designed to have a modified elbow-hinge amino acid sequence, leading to increased direct cell death induction and ADCC activities. In PMN clinical studies, ocrelizumab and obinutuzumab showed promising results, while ofatumumab displayed mixed results. However, there is a lack of randomized controlled trials with large samples, especially direct head-to-head comparisons. Alternative molecular mechanisms have been suggested in this context to explore novel therapeutic strategies. B cell activator-targeted, plasma cell-targeted and complement-directed treatments may lead to novel therapy paradigms for PMN. Exploratory strategies for the use of drugs with different mechanisms, such as a combination of rituximab and cyclophosphamide and a steroid, a combination of rituximab and a calcineurin inhibitor, may provide more rapid and efficient remission, but the combination of standard immunosuppression with rituximab could increase infection risk.

Efficacy of low or heavy rituximab‑based protocols and comparison with seven regimens in idiopathic membranous nephropathy: a systematic review and network meta-analysis

OBJECTIVE

Numerous studies have demonstrated the efficiency of tacrolimus + rituximab and rituximab in idiopathic membranous nephropathy (IMN). But optimal dosages of rituximab for IMN are still controversial. This network meta-analysis (NMA) was conducted to compare the efficacy of different rituximab dosages and other main treatments in IMN treatment.

METHODS

Randomized controlled trials (RCTs) and observational studies analyzing nine therapeutic regimens for IMN were included from some databases. Network comparisons were performed to analyze the rates of total remission (TR) and relapse rate. The surface under the cumulative ranking area (SUCRA) was calculated to rank interventions.

RESULTS

Twelve RCTs and 12 observational studies involving 1724 patients were pooled for comparison of 9 interventions. This NMA demonstrated steroids + tacrolimus was ranked first in the aspect of total remission at 6 months (92%) and 12 months (81.3%). The total remission rate associated with tacrolimus + rituximab increased rapidly between the sixth (SUCRA 22.5%) and the twelfth month (SUCRA 63.9%). Tacrolimus and cyclosporine A were associated with higher total remission at 6 months (78.8% and 65.4%, separately) and decreased at 12 months (58.1 and 34.9%, separately). Steroids + cyclophosphamide, rituximab (Heavy dose) and rituximab (Low dose) had stable remission rates at 6 (63.7%, 46.6%, and 19.4%) and 12 months (SUCRA 66.9%, 39.6%, and 28.8%). Tacrolimus and cyclosporine A were associated with a significantly higher risk of relapse than that with steroids + cyclophosphamide, rituximab (Heavy dose), and rituximab (Low dose).

CONCLUSIONS

For IMN in adults, steroids + tacrolimus was ranked first in the aspect of total remission, followed by steroids + cyclophosphamide and steroids + cyclosporine A. The TR associated with rituximab (Heavy and Low dosage) at 12 months was higher than that at 6 months. And rituximab (Heavy dose) achieves a higher rate of total remission than that of rituximab (Low dose).

Primary membranous nephropathy: an endless story

Primary membranous nephropathy (PMN) is an autoimmune disease caused by the attack of autoantibodies against podocyte antigens leading to the in situ production of immune complexes. However, the etiology is unknown and the pathogenesis is still far from being completely elucidated. MN is prevalently idiopathic or primary, but in about 20-30% of cases it is secondary to chronic infections, systemic diseases, exposure to drugs, or malignancy. The differentiation between primary and secondary MN may be difficult, particularly when MN precedes signs and symptoms of the original disease, as in some cases of cancer or systemic lupus erythematosus. The natural course of PMN is variable, but in the long term 40-60% of patients with nephrotic syndrome progress to end-stage renal disease (ESRD) or die from thrombotic or cardiovascular events. PMN is a treatable disease. Patients with asymptomatic proteinuria should receive supportive care. Immunosuppressive treatments should be given to patients with nephrotic syndrome or risk of progression. The most frequently adopted treatments rely on cyclical therapy alternating steroids with a cytotoxic agent every other month, i.e., rituximab at different doses, or calcineurin inhibitors plus low-dose steroids. A good rate of response may be obtained but relapses can occur. Randomized controlled trials, with adequate size, long-term follow-up, and fair definition of endpoints are needed to identify treatment with the best therapeutic index.

Treatment of membranous nephropathy: Perspectives on current and future therapies

Primary membranous nephropathy remains one of the most frequent causes of nephrotic syndrome in adults. It is an autoimmune disorder in which auto-antibodies target antigens at the podocytes cell membrane-basement membrane interface. Our understanding of membranous nephropathy has expanded dramatically as of late. After the initial discovery of the phospholipase A2 receptor auto-antibody in 2009, eight more antigens have been discovered. These discoveries have led to refinement in our understanding of the pathogenesis, diagnosis, and natural history of primary membranous nephropathy. Now, many experts advocate for redefining primary membranous nephropathy based on antigen, potentially shedding the primary and secondary nomenclature. Recently, therapies for primary membranous have also expanded. Immunosuppressive therapies like cyclophosphamide and rituximab, which primarily target B-cells, remain the cornerstone of therapy. However, there is still significant room for improvement, as many as 30-40% do not respond to this therapy according to recent trials. Additionally, drugs targeting complement, and other novel therapies are also under investigation. In this review we will discuss the available therapies for primary membranous nephropathy in light of recent clinic trials like GEMRITUX, MENTOR, RI-CYCLO, and STARMEN, as well as management strategies. While the last 10 years have seen a boom in our mechanistic understanding of this ever-diversifying disease, we are likely to see a similar boom in the therapeutic options in the years to come.

Efficacy and safety of rituximab for primary membranous nephropathy with different clinical presentations: a retrospective study

Background

Rituximab (RTX) is gaining increasing clinical acceptance in the treatment of primary membranous nephropathy (PMN), with demonstrated efficacy and safety. However, there are few clinical studies on RTX for PMN in Asian populations, especially in China.

Methods

To observe and analyse the efficacy and safety of RTX treatment, 81 patients with PMN suffering from nephrotic syndrome (NS) were enrolled and divided into an initial therapy group, a conventional immunosuppressive therapy relapse group, and a conventional immunosuppressive therapy ineffective group according to their pre-RTX treatment background. Patients in each group were followed up for 12 months. The primary outcome was clinical remission at 12 months, and the secondary outcomes were safety and the occurrence of adverse events.

Results

At 12 months, 65 of 81 (80.2%) patients achieved complete (n=21, 25.9%) or partial (n=44, 54.3%) remission after rituximab treatment. Thirty-two of 36 (88.9%) patients in the initial therapy group, 11 of 12 (91.7%) patients in the relapse group and 22 of 33 (66.7%) patients in the ineffective group achieved clinical remission. All 59 patients with positive anti-PLA2R antibodies showed a decreasing trend in antibody levels after RTX treatment, and 55 (93.2%) of them achieved antibody clearance (<20 U/mL). Logistic regression analysis showed that a high anti-PLA2R antibody titer (OR=0.993, P=0.032) was an independent risk factor for nonremission. Adverse events occurred in 18 (22.2%) patients, of which 5 (6.2%) were serious adverse events, and none were malignant or otherwise fatal.

Conclusion

RTX alone can effectively induce remission PMN and maintain stable renal function. It is recommended as the first choice of treatment and is also effective in patients who relapse and have poor responses to conventional immunosuppressive therapy. Anti-PLA2R antibodies can be used as a marker for RTX treatment monitoring, and antibody clearance is necessary to achieve and improve the rates of clinical remission.

Implications of rituximab pharmacokinetic and pharmacodynamic alterations in various immune-mediated glomerulopathies and potential anti-CD20 therapy alternatives

The specific B-cell depleting anti-CD20 monoclonal antibody rituximab (RTX) is effective in terms of the treatment of various immune-mediated glomerulopathies. The administration of RTX has been shown to be reliable and highly effective particularly in patients with ANCA-associated vasculitis, which is manifested predominantly with non-nephrotic proteinuria. Stable long-term B-cell depletion is usually readily attained in such patients using standard dosing regimens. However, in patients with nephrotic syndrome and non-selective proteinuria, the RTX pharmacokinetics is altered profoundly and RTX does not maintain high enough levels for a sufficiently long period, which may render RTX treatment ineffective. Since complement-derived cytotoxicity is one of the important modes of action of RTX, hypocomplementemia, frequently associated with systemic lupus erythematodes, may act to hamper the efficacy of RTX in the treatment of patients with lupus nephritis. This review provides a description of RTX pharmacokinetics and pharmacodynamics in several selected glomerulopathies, as well as the impact of proteinuria, anti-drug antibodies and other clinical variables on the clearance and volume of distribution of RTX. The impact of plasmapheresis and peritoneal dialysis on the clearance of RTX is also discussed in the paper. A review is provided of the potential association between pharmacokinetic and pharmacodynamic alterations in various kidney-affecting glomerular diseases, the sustainability of B-cell depletion and the clinical efficacy of RTX, with proposals for potential dosing implications. The role of therapeutic drug monitoring in treatment tailoring is also discussed, and various previously tested RTX dosing schedules are compared in terms of their clinical and laboratory treatment responses. Since alternative anti-CD20 molecules may prove effective in RTX unresponsive patients, their pharmacokinetics, pharmacodynamics and current role in the treatment of glomerulopathies are also mentioned.

Toxic Occupational Exposures and Membranous Nephropathy

BACKGROUND AND OBJECTIVES

Membranous nephropathy is a rare autoimmune kidney disease whose increasing prevalence in industrialized countries pleads for the involvement of an environmental factor in the development of the disease. In addition, the predominance of men in membranous nephropathy, classically attributed to biologic or genetic differences between men and women, could also be due to different occupational exposures. To support this hypothesis, we sought to describe the toxic occupational exposures of patients with membranous nephropathy.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this observational epidemiologic study, we compared the occupations and toxic occupational exposures of 100 patients with membranous nephropathy with those of the general population, consisting of two cohorts of 26,734,000 and 26,500 French workers. We then compared the characteristics of patients exposed to an occupational toxic substance with those of unexposed patients.

RESULTS

Patients with membranous nephropathy worked more frequently in the construction sector than the general population (33% versus 7%, P<0.001). This difference remained significant by age and sex. They were also more frequently exposed to toxic substances, such as asbestos (16% versus 5%, P<0.001), lead (9% versus 1%, P<0.001), or organic solvents (37% versus 15%, P<0.001), than the general population. The predominance of men in the subgroup of patients occupationally exposed to toxic substances was not observed in unexposed individuals (organic solvents: 80% men versus 41%, P<0.001; asbestos: 90% men versus 55%, P=0.004). In addition, patients with phospholipase A2 receptor 1 (PLA2R1) epitope spreading were more frequently exposed to asbestos and organic solvents than patients without epitope spreading (32% versus 7%, P=0.02 and 74% versus 43%, P=0.02, respectively), with a dose-dependent effect.

CONCLUSIONS

Patients with membranous nephropathy were more frequently exposed to certain occupational toxic substances, such as asbestos and organic solvents, than the general population. This occupational exposure was more frequent in men and in patients with PLA2R1 epitope spreading.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Immunopathological Analysis in a French National Cohort of Membranous Nephropathy (IHMN), NCT04326218.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2022_10_25_CJN02930322.mp3.

Rituximab Dosing in Glomerular Diseases: A Scoping Review

Purpose of Review

Rituximab is increasingly prescribed for glomerular diseases. However, the recently published Kidney Disease Improving Global Outcomes (KDIGO) 2021 Clinical Practice Guideline for the Management of Glomerular Diseases lacks details on recommended dosing regimens for most individual glomerular diseases. We performed this scoping review summarizing the evidence for rituximab dosing in glomerular disease.

Sources of Information

PubMed database.

Methods

The PubMed search methodology was developed with a medical librarian and performed by the first, with review by a second, author. Randomized controlled trials (RCTs) and prospective cohort studies (PCSs) examining rituximab efficacy and/or safety in antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV), membranous nephropathy (MN), lupus nephritis (LN), or podocytopathies (minimal change disease or focal segmental glomerulosclerosis [FSGS]) were included. Fifty-three studies (14 RCTs and 39 PCSs) were included.

Key Findings

We identified 16 different rituximab dosing regimens studied as induction therapy for one or more of the 5 glomerular diseases of interest. The most frequently studied rituximab induction regimens were 1000 mg as 2 doses 2 weeks apart (17 studies, 32%) and 4 doses of 375 mg/m²/week (18 studies, 33.9%). Twenty-six studies (49%) examined rituximab as monotherapy or in conjunction with corticosteroids alone, while the remaining studies examined rituximab as part of combination immunosuppression. Adapting treatment to achieve B-cell depletion, with frequent evaluation of disease-specific biomarkers, might prove the optimal approach to achieving and maintaining remission. Rituximab might also enable steroid minimization or avoidance.

Limitations

Restriction of the search to a single database and to studies published in the English language, and with an accompanying abstract, could have led to selection bias. While the search was limited to prospective observational studies and RCTs, no formal assessment of study quality was performed.

Rituximab in patients with membranous nephropathy and kidney insufficiency

Introduction: Patients with membranous nephropathy and kidney insufficiency have an extremely high risk of progression to end-stage renal disease. Whether rituximab can effectively treat membranous nephropathy patients with renal dysfunction remains unknown at present. The aim of our study was to evaluate the effectiveness and safety of rituximab (RTX) in membranous nephropathy with kidney insufficiency.

Methods: We retrospectively analyzed the clinical data of 35 membranous nephropathy patients with kidney insufficiency administered in the First Affiliated Hospital of Zhengzhou University between January 2020 and December 2021. Patients were followed every 1–3 months for a total of 6 months. Clinical data were collected including anti-phospholipase A2 receptor antibody (anti-PLA2R antibody) quantification, 24-h urinary protein, serum albumin, and serum creatinine. The percentage of patients who achieved clinical remission was measured.

Results: There were 7 (20%) patients who achieved complete or partial response at 6 months after RTX treatment. After 6 months of treatment, patients were clinically improved as evidenced by significant improvements in anti- PLA2R antibody titer [7.70 (5.72, 16.72) vs. 59.20 (17.70, 187.50) RU/ml, p < 0.001], 24-h urine protein [7.04 (4.43, 8.90) vs. 10.15 (4.83, 13.57) g/d, p < 0.001], serum albumin [30.55 (24.97, 33.27) vs. 21.40 (16.75, 25.00)g/L, p < 0.001], serum creatinine [99.50 (75.25, 140.25) vs. 152.00 (134.50, 232.50) µmol/L, p = 0.022], and estimated glomerular filtration rate (eGFR) [78.29 (50.15, 101.55) vs. 41.12 (26.53, 51.41) ml/min/1.73 m², p = 0.045]. There were no significantly differences between responders and nonresponders in the baseline levels of anti-PLA2R antibodies, proteinuria, serum albumin, and renal function. After the RTX treatment, anti-PLA2R antibodies turned negative in all responders, but the antibody level persisted maintained positive in all but 5 nonresponders. The patients who achieved response maintained a stable kidney function during the study period, with eGFR 29.03 (28.76, 35.07) ml/min/1.73 m² before rituximab treatment and 62.73 (62.34, 63.13) ml/min/1.73 m² at the end of follow-up (p = 0.053).

Conclusion: RTX therapy might be an alternative treatment in reducing proteinuria and maintaining stable renal function among membranous nephropathy patients even with kidney insufficiency.

Level of interleukin-35 in patients with idiopathic membranous nephropathy and its predictive value for remission time

Objective

As a member of interleukin-12 family, interleukin-35 (IL-35) plays an important regulatory role in immune response. The relationship between IL-35 and idiopathic membranous nephropathy (IMN) is still unclear, and the purpose of this study is to clarify the relationship between IL-35 and disease activity and remission of IMN.

Methods

This study was a single-center, retrospective study in which all patients were diagnosed with IMN by renal biopsy or aPLA2R titer and treated with Mahuang Fuzi and Shenzhuo Decoction (MFSD). A follow-up was conducted with the endpoint of clinical complete or partial remission (CR+PR). Levels of serum IL-35 were measured and its relationship with IMN remission were analyzed. The regulatory T cell (Treg) and inducible IL-35 producing Tregs (iTR35) in peripheral blood of IMN patients were detected by flow cytometry.

Results

A total of 76 IMN patients (age 51.95 ± 13.29) were followed-up for 18 (12, 24) months. The level of serum IL-35 in all patients increased after treatment, but the degree of increase in remission group was significantly higher than that in no remission (NR) group (117.6% vs 83.7%, P<0.01). The baseline IL-35 level in remission group was higher than that in NR group (174.87 vs.151.87 pg/ml, P=0.016). Cox regression analysis showed that baseline IL-35 level was a independent risk factor for IMN remission (HR 1.081, 95%CI 1.048-1.116, P<0.001). Patients with baseline IL-35 lower than the lower quartile (≤145.49 pg/ml) had an average remission time twice as long as those with baseline IL-35 higher than the upper quartile (> 203.05 pg/ml) (12mon vs. 24mon, P<0.01). The baseline IL-35 can predict the remission time of IMN patients with either aPLA2R positive (AUC=0.673) or negative (AUC=0.745). Analysis of 18 patients with IMN showed that IL-35 level had a higher correlation with iTR35, but not Treg (r=0.613, P<0.05).

Conclusions

The level of IL-35 in patients with IMN showed an increasing trend with the progress of treatment, and the baseline IL-35 could predict the remission time of IMN patients, including those patients with negative aPLA2R. The level of IL-35 is related to the number of iTR35 cells.

T Cell Help in the Autoreactive Germinal Center

The germinal center serves as a site of B cell selection and affinity maturation, critical processes for productive adaptive immunity. In autoimmune disease tolerance is broken in the germinal center reaction, leading to production of autoreactive B cells that may propagate disease. Follicular T cells are crucial regulators of this process, providing signals necessary for B cell survival in the germinal center. Here we review the emerging roles of follicular T cells in the autoreactive germinal center. Recent advances in immunological techniques have allowed study of the gene expression profiles and repertoire of follicular T cells at unprecedented resolution. These studies provide insight into the potential role follicular T cells play in preventing or facilitating germinal center loss of tolerance. Improved understanding of the mechanisms of T cell help in autoreactive germinal centers provides novel therapeutic targets for diseases of germinal center dysfunction.

Advances in the Management of Primary Membranous Nephropathy and Rituximab-Refractory Membranous Nephropathy

Primary membranous nephropathy (pMN) is an auto-immune disease characterized by auto-antibodies targeting podocyte antigens resulting in activation of complement and damage to the glomerular basement membrane. pMN is the most common cause of nephrotic syndrome in adults without diabetes. Despite a very heterogeneous course of the disease, the treatment of pMN has for many years been based on uniform management of all patients regardless of the severity of the disease. The identification of prognostic markers has radically changed the vision of pMN and allowed KDIGO guidelines to evolve in 2021 towards a more personalized management based on the assessment of the risk of progressive loss of kidney function. The recognition of pMN as an antibody-mediated autoimmune disease has rationalized the use immunosuppressive drugs such as rituximab. Rituximab is now a first line immunosuppressive therapy for patients with pMN with proven safety and efficacy achieving remission in 60-80% of patients. For the remaining 20-40% of patients, several mechanisms may explain rituximab resistance: (i) decreased rituximab bioavailability; (ii) immunization against rituximab; and (iii) chronic glomerular damage. The treatment of patients with rituximab-refractory pMN remains controversial and challenging. In this review, we provide an overview of recent advances in the management of pMN (according to the KDIGO 2021 guidelines), in the understanding of the pathophysiology of rituximab resistance, and in the management of rituximab-refractory pMN. We propose a treatment decision aid based on immunomonitoring to identify failures related to underdosing or immunization against rituximab to overcome treatment resistance.

Therapies for Membranous Nephropathy: A Tale From the Old and New Millennia

Primary Membranous Nephropathy (PMN) is the most frequent cause of nephrotic syndrome in adults. If untreated, PMN can lead to end-stage renal disease; moreover, affected patients are at increased risk of complications typical of nephrotic syndrome such as fluid overload, deep vein thrombosis and infection. The association of PMN with HLA-DQA1 and the identification in around 70% of cases of circulating autoantibodies, mainly directed towards the phospholipase A2 receptor, supports the autoimmune nature of the disease. In patients not achieving spontaneous remission or in the ones with deteriorating kidney function and severe nephrotic syndrome, immunosuppression is required to increase the chances of achieving remission. The aim of this review is to discuss the evidence base for the different immunosuppressive regimens used for PMN in studies published so far; the manuscript also includes a section where the authors propose, based upon current evidence, their recommendations regarding immunosuppression in the disease, while highlighting the still significant knowledge gaps and uncertainties.

Mathematical modeling of tumor-immune system interactions: the effect of rituximab on breast cancer immune response

tBregs are a newly discovered subcategory of B regulatory cells, which are generated by breast cancer, resulting in the increase of Tregs and therefore in the death of NK cells. In this study, we use a mathematical and computational approach to investigate the complex interactions between the aforementioned cells as well as CD8⁺ T cells, CD4⁺ T cells and B cells. Furthermore, we use data fitting to prove that the functional response regarding the lysis of breast cancer cells by NK cells has a ratio-dependent form. Additionally, we include in our model the concentration of rituximab - a monoclonal antibody that has been suggested as a potential breast cancer therapy - and test its effect, when the standard, as well as experimental dosages, are administered.

Acute chest pain and dyspnoea as clinical presentation of primary membranous nephropathy. A case report and literature review

Membranous nephropathy (MN) is the commonest cause of nephrotic syndrome (NS) in adult male patients worldwide. Most of the cases (80%) are idiopathic (primary MN, PMN), whereas about 20% are associated with autoimmune diseases, malignancies or exposures (secondary MN). PMN is a kidney-specific autoimmune glomerular disease mediated by antibodies to the M-type phospholipase A2 receptor (anti-PLA2R) (85%), thrombospondin type 1 domain containing 7A (THSD7A) (3-5%), or by other still unidentified mechanisms (10%). Most of the patients with PMN present with NS (80%). Clinical course of PMN is characterised by spontaneous remissions (40%) and relapses (15-30%). One third develop end-stage renal disease (ESRD) within 5 to 15 years from the onset. Anti-PLA2R/THSD7A antibodies levels correlate with proteinuria, clinical course, and outcomes. The treatment still remains matter of debate. Hypertension, proteinuria, and hyperlipidaemia must be treated in all patients. Immunosuppressive therapy is indicated in patients with elevated anti-PLA2R/THSD7A levels and proteinuria >3.5 g/d at diagnosis. With proper management, only 10% or less will develop ESRD over the subsequent 10 years. Here we report a case of a 34-year-old male patient with a ten-year history of asymptomatic PMN, treated with ACE-inhibitors, who presented to our emergency room for acute chest pain and exertional dyspnoea due to ESRD that required urgent dialysis. (www.actabiomedica.it).

Rituximab Therapy for Adults with Nephrotic Syndromes: Standard Schedules or B Cell-Targeted Therapy?

Rituximab is a chimeric anti-CD20 monoclonal antibody. It acts mainly through complement-dependent cytotoxicity on B cells expressing the CD20 marker. In this review, we analyse the efficacy and possible pitfalls of rituximab to treat nephrotic syndromes by taking into account pharmacological considerations and CD19 marker testing utility. Despite the fact that the drug has been in use for years, efficacy and treatment schedules in adults with nephrotic syndrome are still a matter of debate. Clinical trials have proven the efficacy and safety of rituximab in idiopathic membranous nephropathy. Data from observational studies also showed the efficacy of rituximab in minimal change disease and focal segmental glomerulosclerosis. Rituximab use is now widely recommended by new Kidney Disease Improved Outcome (KDIGO) guidelines in membranous nephropathy and in frequent-relapsing, steroid-dependent minimal change disease or focal segmental glomerulosclerosis. However, rituximab response has a large interindividual variability. One reason could be that rituximab is lost in the urine at a higher extent in patients with nonselective nephrotic proteinuria, exposing patients to different rituximab plasma levels. Moreover, the association between CD19+ levels and clinical response or relapses is not always present, making the use of this marker in clinical practice complex. High resolution flow cytometry has increased the capability of detecting residual CD19+ B cells. Moreover, it can identify specific B-cell subsets (including IgG-switched memory B cells), which can repopulate at different rates. Its wider use could become a useful tool for better understanding reasons of rituximab failure or avoiding unnecessary retreatments.

Rituximab for the treatment of idiopathic membranous nephropathy with nephrotic syndrome: a systematic review and meta-analysis

Background/aim

This meta-analysis comprehensively investigated the efficacy and safety of rituximab (RTX) in patients with idiopathic membranous nephropathy (IMN).

Materials and methods

We searched the MEDLINE, EMBASE and Cochrane Registry of Controlled Trials databases from January 2000 to January 2020. Studies evaluating the efficacy and safety of RTX in the treatment of IMN with nephrotic syndrome (NS) were included.

Results

Nine studies (total of 357 patients) were included in the meta-analysis. The pooled complete response and overall response (OR) rates at 12 months were 13.2% [95% con fidence interval (CI), 0.09–0.18] and 60% (95% CI, 0.48–0.72), and those at 24 months were 27.8% (95% CI, 0.22–0.34) and 66% (95% CI, 0.6–0.72), respectively. The pooled OR rates for the low-, standard-, and high-dose groups were 39.3%, 64%, and 60%, respectively, and those for the first-line and second-line groups were 58% and 54%, respectively.

Conclusion

Treatment of IMN with RTX has comparable efficacy to other immunosuppressive treatments (ISTs). RTX has the advantages of no requirement for steroids and lower rates adverse event and relapse rates. Patients who relapse or are resistant to other IST agents also respond to RTX. RTX-based regimens and other B-cell-targeted therapies may represent the future of IMN therapy.

How Times Have Changed! A Cornucopia of Antigens for Membranous Nephropathy

The identification of the major target antigen phospholipase A2 receptor (PLA2R) in the majority of primary (idiopathic) cases of membranous nephropathy (MN) has been followed by the rapid identification of numerous minor antigens that appear to define phenotypically distinct forms of disease. This article serves to review all the known antigens that have been shown to localize to subepithelial deposits in MN, as well as the distinctive characteristics associated with each subtype of MN. We will also shed light on the novel proteomic approaches that have allowed identification of the most recent antigens. The paradigm of an antigen normally expressed on the podocyte cell surface leading to in-situ immune complex formation, complement activation, and subsequent podocyte injury will be discussed and challenged in light of the current repertoire of multiple MN antigens. Since disease phenotypes associated with each individual target antigens can often blur the distinction between primary and secondary disease, we encourage the use of antigen-based classification of membranous nephropathy.

The management of membranous nephropathy - an update

In the last decades several important advances have taken place in the understanding of the pathogenesis underlying membranous nephropathy, which have sparked renewed interest in its management. Four landmark trials in membranous nephropathy, and a fifth clinical trial-which was a pilot study-, have been published in the last years. The results from some of these trials have had a significant impact in the recommendations included in the 2021 Kidney Disease: Improving Global Outcomes (KDIGO) Guideline for the Management of Glomerular Diseases, which represent a significant step forward compared to the previous guideline in several aspects such as diagnosis, disease monitoring and treatment strategies. However, considering the rapidly evolving advances in the knowledge of membranous nephropathy and the recent publication of the STARMEN and RI-CYCLO trials, several recommendations contained in the guideline warrant updates. This manuscript provides a perspective of the Immunonephrology Working Group of the European Renal Association (ERA) regarding the management of membranous nephropathy in native kidneys of adult patients.

Rituximab Immunomonitoring Predicts Remission in Membranous Nephropathy

Primary membranous nephropathy (pMN) is an autoimmune kidney disease and a common cause of nephrotic syndrome in adults. Rituximab is becoming a first line therapy for patients with persistent nephrotic syndrome with proven safety and efficacy, achieving remission in 60%–80% of cases. For the remaining 20%–40% of patients there is an urgent need to identify early biomarkers of resistance to rituximab to adapt therapeutic management. In nephrotic patients, rituximab is found in the blood more transiently than in other autoimmune diseases without proteinuria, due to rituximab wasting in the urine. However, rituximab immunomonitoring is not routinely performed. We evaluated the predictive value of serum rituximab levels in patients with pMN three months after rituximab injection (month-3) on clinical remission rates six months (month-6) and 12 months (month-12) after injection and investigated predictive factors for serum rituximab levels at month-3. Sixty-eight patients treated with rituximab between July 2015 and January 2020 from two French nephrology centers were included. We identified residual rituximab levels at month-3 as a novel early predictor of remission at month-6 (p <0.0001) and month-12 (p = 0.001). Reduced likelihood of remission in patients with undetectable rituximab at month-3 was associated with lower serum albumin and higher anti-PLA2R1 titers at baseline and with lower serum albumin, higher proteinuria, higher CD19⁺ counts and higher anti-PLA2R1 titers during follow-up. In multivariate analysis, high baseline proteinuria and undetectable rituximab levels at month-3 were independent risk factors for treatment failure at month-6 and high baseline weight and undetectable rituximab levels at month-3 were independent risk factors for treatment failure at month-12. We identified serum albumin at baseline as a predictive factor for serum rituximab levels at month-3. Patients with serum albumin below 22.5 g/L at baseline had an 8.66-fold higher risk of having undetectable rituximab levels at month-3. Therefore, rituximab immunomonitoring in pMN patients treated with rituximab would allow the detection of patients at risk of treatment failure as early as month-3. Studies are needed to assess whether patients with low residual rituximab levels at month-3 may benefit from an early additional course of rituximab.

Remissions in Patients with Idiopathic Membranous Nephropathy Treated with Rituximab in Senegal

Objectives: This study aimed to evaluate the efficacy of Rituximab in the management of idiopathic membranous nephropathy (IMN) based on the following criteria: (I) Biological remission at three months (M3) and six months (M6); (II) change in mean proteinuria (24PU), mean serum albumin, and mean serum creatinine at M3 and M6; (III) and side effects. Methods: This retrospective descriptive and analytical study included patients with histologically confirmed IMN with positive plasma anti-PLA2R antibodies who received at least one dose of Rituximab after six months of follow-up without spontaneous remission. Patients with unexplainable records were not included. Results: A total of five patients (P1, P2, P3, P4, and P5), including four males and one female were analyzed. The mean age was 44.20 ± 23.14 years. All patients had IMN type 2. At inclusion, the mean albuminemia, mean creatinine, and mean 24hPU levels were 15.56 ± 5.27 g/L, 17.3 ± 7.6 mg/L, and 6.54 ± 1.13 g/24h, respectively. The median anti-PLA2R antibody titer was 100 IU with extremes of 10 and 800 IU. Partial remission was noted in three patients at M3 (P2, P4, and P5), and it was maintained until M6 in P2. No complete remission was observed. A significant decrease in mean 24hPU at M3 was noted (P < 0.001). Generalized pruritus associated with seizures was noticed in P4 after the first dose of Rituximab. Conclusions: Partial remission was noted in three patients at M3, and one patient maintained this remission at M6. Rituximab significantly reduced 24hPU at M3 after administration. Rituximab administration was well tolerated by the patients.

Combination of ultra-low dose rituximab and low dose tacrolimus versus tacrolimus alone in the treatment of non-responsive idiopathic membranous nephropathy: a Chinese retrospective cohort study

INTRODUCTION

Some patients with idiopathic membranous nephropathy (iMN) do not respond to cyclophosphamide plus steroids treatment, and we define them as non-responsive iMN. The combined regimen of rituximab (RTX) and tacrolimus (TAC) has an excellent effect on this kind of non-responsive iMN patients; however, the optimal dose is still unclear. In this retrospective study, we comapred the efficacy and safety of ultra-low dose RTX plus low-dose TAC therapy versus standard TAC monotherapy in patients with non-responsive iMN.

MATERIALS AND METHODS

Sixty-seven Chinese non-responsive iMN patients were included. There were 41 patients received standard tacrolimus monotherapy (TAC) and 26 patients received ultra-low dose rituximab plus low dose tacrolimus (RTX/TAC) combination therapy. All patients were observed for 12 months.

RESULTS

18 patients (18/26, 69.2%) in the RTX/TAC group and 17 patients (17/41, 41.5%) in the TAC group achieved clinical response after 12-month follow-up (P=0.044). The median time for achieving response in the two groups was 3.0 months. As indicated by Kaplan-Meier curve, the response rate in the RTX/TAC group was higher than that in the TAC group (P=0.015). 24-hour proteinuria, serum albumin, estimated glomerular filtration rate (eGFR) and serum creatinine in the two groups were comparable at baseline; howerver, after 12-month follow up, they were significantly improved in the RTX/TAC group compared with the TAC group (P<0.05). B-cell depletion was achieved in all patients in the RTX/TAC group during the whole follow-up period. Pneumonia, urinary tract infections and glucose intolerance were the major side effects observed in this study. All adverse events were mild, and the cumulative incidence was lower in the RTX/TAC group compared with that in the TAC group (9 (34.6%) vs 27 (65.9%), P=0.023).

CONCLUSION

The combination of ultra-low dose rituximab and low dose tacrolimus is more effective in inducing proteinuria response, improving eGFR and serum albumin in non-responsive iMN patients than standard tacrolimus monotherapy. The combined treatment also has higher safty.

A Novel Insight into the Role of PLA2R and THSD7A in Membranous Nephropathy

Membranous nephropathy (MN) is an organ-restricted autoimmune disease mainly caused by circulating autoantibodies against podocyte antigens, including the M-type phospholipase A2 receptor (PLA2R) and thrombospondin domain-containing 7A (THSD7A). Antibodies against PLA2R are present in 70%-80% and against THSD7A in 2% of adult patients, which provides a paradigm shift in molecular diagnosis and management monitoring. Both antigens share some similar characteristics: they are expressed by podocytes and have wide tissue distributions; they are bound by autoantibodies only under nonreducing conditions, and the subtype of most autoantibodies is IgG4. However, the factors triggering autoantibody production as well as the association among air pollution, malignancy, and the pathogenesis of MN remain unclear. In this review, we discuss the similarity between the pathological mechanisms triggered by disparate antigens and their associated diseases. Furthermore, we demonstrated the possibility that PM2.5, malignancy, and gene expression specifically induce exposure of these antigens through conformational changes, molecular mimicry, or increased expression eliciting autoimmune responses. Thus, this review provides novel insights into the pathological mechanism of MN.

Membranous Nephropathy: It Is Time to Go Back to the Future

CONTEXT

Membranous nephropathy (MN) is an immune-mediated glomerular disease that can lead to nephrotic syndrome and progressive kidney function loss. The cyclic steroid-cyclophosphamide regimen (the modified Ponticelli protocol) and the monoclonal anti-CD20 antibody rituximab have been advocated as effective therapies to improve renal outcomes, but a direct comparison of these treatments had never been carried out in a prospective study. Subject of Review: Scolari et al. [J Am Soc Nephrol. 2021;32:972-82] recently reported the results of a pilot randomized controlled trial (RI-CYCLO) designed to provide direct estimates of the effect of rituximab (1 g × 2) compared to the cyclic steroid-cyclophosphamide regimen in 74 patients with MN. The proportion of patients with complete remission at 12 months was higher in the cyclic regimen arm than that of rituximab (32 and 16%, respectively), but the difference was not statistically significant in intention-to-treat analyses. Interestingly, differences in the cumulative incidence of complete and partial remissions between treatment arms progressively reduced over the follow-up and became virtually nonexistent from 24 months (>80% in both groups). The frequency of serious and nonserious adverse events was similar between the 2 treatment arms. Infusion reactions and drug discontinuation were more common with rituximab, while infections and leukopenia were more frequently observed with the cyclic regimen. The risk of cancer was similar in the 2 allocation groups, but the limited follow-up length did not allow to draw definitive conclusions. Independent of treatment allocation, 18% of patients experienced at least 1 relapse after achieving complete or partial remission. Second Opinion: Notwithstanding the intrinsic limitations of a pilot study, the RI-CYCLO trial represents an important milestone in the treatment of MN. Findings from this study support the hypothesis that the cyclic regimen and rituximab may have comparable efficacy in inducing disease remission over the long term. Considering its potentially better-albeit not yet formally proven-long-term safety profile, rituximab could be considered as a first-line therapy for most patients with MN. Several questions remain to be addressed, including rituximab ideal dose and its efficacy in patients with a significant reduction in glomerular filtration rate. In light of RI-CYCLO results, a large-scale trial to assess rituximab noninferiority to the cyclic regimen would require the enrollment of thousands of patients, and it would be probably unfeasible within a reasonable time frame. In our opinion, resources should be allocated to provide an answer to the pressing matter of treatment nonresponse and intolerance, which may be addressed in the near future with novel therapeutic strategies.

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.

Rituximab in Membranous Nephropathy

Membranous nephropathy (MN) is the most common cause of primary nephrotic syndrome among adults. The identification of phospholipase A2 receptor (PLA2R) as target antigen in most patients changed the management of MN dramatically, and provided a rationale for B-cell depleting agents such as rituximab. The efficacy of rituximab in inducing remission has been investigated in several studies, including 3 randomized controlled trials, in which complete and partial remission of proteinuria was achieved in approximately two-thirds of treated patients. Due to its favorable safety profile, rituximab is now considered a first-line treatment option for MN, especially in patients at moderate and high risk of deterioration in kidney function. However, questions remain about how to best use rituximab, including the optimal dosing regimen, a potential need for maintenance therapy, and assessment of long-term safety and efficacy outcomes. In this review, we provide an overview of the current literature and discuss both strengths and limitations of "the new standard."

Autoantibodies in the Diagnosis, Monitoring, and Treatment of Membranous Nephropathy

The discovery of anti-podocyte antibodies in primary membranous nephropathy (MN) has revolutionized our approach toward the diagnosis and treatment of this disease. Evaluation of serum levels of anti-podocyte antibodies paved the way for non-invasive diagnosis and helped distinguish between primary and secondary MN although the relationship between anti-podocyte antibodies and cancer remains to be elucidated. Serum levels of anti-PLA2R antibodies directed against the major podocyte autoantigen are related to MN activity and the decrease in serum levels of anti-PLA2R antibodies in response to treatment (immunologic remission) also serves as an early indicator of the later putative proteinuric remission, enabling personalization of the treatment. The serum levels of anti-podocyte antibodies also enable the prediction of renal outcomes in terms of both remission and the risk of progression to end-stage renal disease. The positivity of anti-PLA2R antibodies before renal transplantation is associated with the risk of recurrence of MN. It remains to be established if all these relations observed in patients with anti-PLA2R antibodies are also valid for expanding spectrum of antibodies directed against recently discovered minor antigens (e.g., THSD7A, NELL-1, semaphorin 3B).

[Rituximab immunomonitoring in autoimmune diseases: a support tool in clinical practice?]

INTRODUCTION

Immune monitoring of monoclonal antibodies is a helpful tool in optimizing the management of patients treated with TNF blockers, especially in gastroenterology. In contrast, studies evaluating the interest of such monitoring are lacking for other monoclonal antibodies used in autoimmune diseases, including rituximab despite its widespread use in the field for almost 15 years. Hence, we conducted a study whose goal was to describe the clinical and biological characteristics of all patients who had a rituximab immune monitoring.

METHODS

All the clinical, biological and therapeutic data attached to the demands (from 2015 onwards) we received for immune monitoring of rituximab (measurements of rituximab serum levels and anti-rituximab antibodies using the drug-sensitive assay LISA-TRACKER Duo Rituximab®), were retrospectively reviewed. Suspected cases of hypersensitivity and secondary non-response were included.

RESULTS

Several medical specialities (nephrology, haematology, neurology, rheumatology, internal medicine) were represented among the 18 records included in the study (out of 23 demands), 10 being suspected cases of hypersensitivity and 8 secondary non-responders. All 6 patients whose symptoms were consistent with the classical presentation of serum sickness, as well as half of the secondary non-responders, were positive for antirituximab antibodies.

CONCLUSION

This detailed real world case study illustrates the potential benefits of rituximab immune monitoring (especially anti-rituximab antibodies) in autoimmune diseases, suggesting it could be helpful in suspected cases of serum sickness, as well as secondary non-response (B-cell non-depletion being an early red flag). Larger and disease-specific studies are warranted to support these findings.

Variability of rituximab and tocilizumab trough concentrations in patients with rheumatoid arthritis

Patients with rheumatoid arthritis (RA) are eligible for treatment with therapeutic monoclonal antibodies (mAbs) that target tumor necrosis factor α (TNFα), as well as others, such as rituximab (RTX) and tocilizumab (TCZ). Although pharmacokinetic variability and the link between concentration-clinical response of anti-TNFα mAbs have been well-described, little is known about RTX and TCZ. We aimed to evaluate the variability of RTX and TCZ serum concentrations in RA patients treated in second-line and the relationship between RTX/TCZ concentrations and the clinical response. Serum mAb trough concentrations of RA patients treated with RTX (n = 35) or TCZ (n = 46) were determined at week 24 by liquid chromatography-tandem mass spectrometry. The clinical response was assessed at week 24 by the change in the disease activity score in the 28 joints-erythrocyte sedimentation rate from baseline (ΔDAS28-Erythrocyte Sedimentation Rate) and according to the European League Against Rheumatism (EULAR) recommendations. RTX and TCZ trough concentrations were highly variable, with a coefficient of variation of 171.3% for RTX (median [10th-90th percentiles]: <1.0 µg/mL [<1.0-5.1]) and 132.6% for TCZ (median [10th-90th percentiles]: 5.4 µg/mL [<1.0-27.8]). Univariate analysis did not identify any determinants of such variability, except cotreatment with methotrexate, which was associated with lower RTX concentrations (P = 0.03). The response to treatment was not related to the RTX or TCZ trough concentration. RTX and TCZ trough concentrations at 24 weeks were highly variable in RA patients treated in the second line, without any link concentration-clinical response having been demonstrated.

Advances in Membranous Nephropathy

Membranous nephropathy (MN) is a rare auto-immune disease where the glomerulus is targeted by circulating auto-antibodies mostly against podocyte antigens, which results in the formation of electron-dense immune complexes, activation of complement and massive proteinuria. MN is the most common cause of nephrotic syndrome in adults leading to severe thrombotic complications and kidney failure. This review is focused on the recent therapeutic and pathophysiological advances that occurred in the last two years. For a long time, we were lacking a head-to-head comparison between cyclophosphamide considered as the gold standard therapy and other medications, notably rituximab. Substantial progress has been achieved owing to three randomized controlled trials. MENTOR (Membranous Nephropathy Trial of Rituximab) and STARMEN (Sequential Therapy with Tacrolimus and Rituximab in Primary Membranous Nephropathy) conclusively established that calcineurin inhibitor-based regimens are slower to result in an immunologic response than rituximab or cyclophosphamide, achieve fewer complete clinical remissions, and are less likely to maintainremission. Rituximab Versus Steroids and Cyclophosphamide in the Treatment of Idiopathic Membranous Nephropathy (RI-CYCLO) suggested that competition between cyclophosphamide and rituximab remains open. Given the technological leap combining laser microdissection of glomeruli and mass spectrometry of solubilized digested proteins, four "new antigens" were discovered including NELL-1 and Semaphorin 3B in so-called primary MN, and exostosins 1 and 2 and NCAM 1 in lupus MN. NELL-1 is associated with about 8% of primary MN and is characterized by segmental immune deposits and frequent association with cancer (30%). Semaphorin 3B-associated MN usually occurs in children, often below the age of two years, where it is the main antigen, representing about 16% of non-lupus MN in childhood. Exostosins 1/2 and NCAM 1 are associated with 30% and 6% of lupus MN, respectively. Exostosins 1/2 (EXT1/2) staining is associated with a low rate of end-stage kidney disease (ESKD) even in mixed classes III/IV+V. These findings already lead to revisiting the diagnostic and therapeutic algorithms toward more personalized medicine.

Membranous nephropathy: diagnosis, treatment, and monitoring in the post-PLA2R era

Membranous nephropathy (MN) is an immune complex-mediated cause of the nephrotic syndrome that can occur in all age groups, from infants to the very elderly. However, nephrotic syndrome in children is more frequently caused by conditions such as minimal change disease or focal segmental glomerulosclerosis, and much less commonly by MN. While systemic conditions such as lupus or infections such as hepatitis B may more commonly be associated as secondary causes with MN in the younger population, primary or "idiopathic" MN has generally been considered a disease of adults. Autoantibodies both to the M-type phospholipase A2 receptor (PLA2R) and to thrombospondin type-1 domain-containing 7A (THSD7A), initially described in adult MN, have now been identified in children and adolescents with MN and serve as a useful diagnostic and monitoring tool in this younger population as well. Whereas definitive therapy for secondary forms of MN should be targeted at the underlying cause, immunosuppressive therapy is often necessary for primary disease. Rituximab has been successfully used in the treatment of MN, and is likely effective in children with MN as well, although dosing in the pediatric population is not well established. This review highlights the new findings in adult and pediatric MN since last reviewed in this journal.