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

Deciphering the causal link between gut microbiota and membranous nephropathy: insights into potential inflammatory mechanisms

BACKGROUND

Membranous nephropathy (MN), a leading cause of adult nephrotic syndrome and renal failure, has been linked to gut microbiota (GM) and their metabolites. However, direct causal relationships and therapeutic implications remain unclear.

METHODS

We utilized a comprehensive GWAS dataset that encompasses GM, metabolites, and MN through two-sample Mendelian randomization (MR) analyses, bidirectional MR evaluations, and detailed sensitivity tests.

RESULTS

We identified strong causal associations between nine specific types of GM, including class Clostridia (OR = 1.816, 95%CI: 1.021-3.236, p = .042), class Melainabacteria (OR = 0.661, 95%CI: 0.439-0.996, p = .048), order Gastranaerophilales (OR = 0.689, 95%CI: 0.480-0.996, p = .044), genus Alistipes (OR = 0.480, 95%CI: 0.223-0.998, p = .049), genus Butyricicoccus (OR = 0.464, 95%CI: 0.216-0.995, p = .048), genus Butyrivibrio (OR = 0.799, 95%CI: 0.639-0.998, p = .048), genus Ruminococcaceae UCG003 (OR = 0.563, 95%CI: 0.362-0.877, p = .011), genus Streptococcus (OR = 0.619, 95%CI: 0.393-0.973, p = .038), and genus Oscillibacter (OR = 1.90, 95%CI: 1.06-3.40, p = .031). Additionally, the metabolite tryptophan also exhibited a significant causal influence on MN (OR = 0.852, 95%CI: 0.754-0.963, p = .010). Sensitivity and reverse MR analyses confirmed the robustness of these findings. Further exploration using gutMGene database suggests that GM may influence MN by affecting the release of inflammatory factors and modulating inflammatory pathways.

CONCLUSION

This study offers a comprehensive understanding of the causal links between GM, their metabolites, and MN, which highlight potential pathways for developing new preventive and therapeutic strategies for this condition.

Treatment of nephrotic syndrome with anti-CD20 therapies in pregnancy: a case series and review of the literature

Membranous nephropathy (MN), focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD) are autoimmune kidney diseases and the most common causes of nephrotic syndrome. Anti-CD20 monoclonal antibodies are now recommended as first-line therapy for MN. Anti-CD20 monoclonal antibodies are also effective in steroid-dependent or frequently relapsing nephrotic syndrome associated with MCD or FSGS. Many women eligible for these treatments are of childbearing age. The impact of anti-CD20 therapies on pregnancy and fetal outcomes remains uncertain, particularly in glomerular diseases. We describe three cases of patients with glomerular disease treated with anti-CD20 therapies in the context of pregnancy and review the literature.

Modified Huangqi Chifeng decoction alleviates podocyte injury on rat with experimental membranous nephropathy

OBJECTIVE

This study aims to investigate the therapeutic effects of modified Huangqi Chifeng decoction (MHCD) on proteinuria in membranous nephropathy (MN) and its potential protective effects on podocytes. Furthermore, we explored whether these effects are associated with the inhibition of the nuclear factor kappa-B (NF-κB) pathway.

METHODS

Passive Heymann nephritis (PHN) rat model was applied with a single tail vein injection of sheep anti-rat Fx1A serum (0.4 ml/100g). All rats were divided into four groups: normal group, PHN group, benazepril group (10 mg/kg), and MHCD group (12.5 g/kg), and were treated for 6 weeks. 24-hour urine protein levels and serum biochemical parameters were measured. Optical microscopy and transmission electron microscopy were performed to assess pathological changes in renal tissues. Additionally, the expression levels of IgG, C5b-9, nephrin, podocin, Wilms' tumor gene 1 (WT-1), and NF-κB p65 were evaluated.

RESULTS

PHN rats exhibited progressive proteinuria over time. However, MHCD treatment significantly reduced levels of proteinuria and triglyceride, while increased levels of albumin. Moreover, MHCD alleviated pathological damage in renal tissues, and reduced the expression of IgG and membrane attack complex (C5b-9). Immunohistochemistry analysis revealed that MHCD increased the expression of nephrin, podocin, and WT-1. Western blot analysis showed that MHCD increased the expression of nephrin and podocin while inhibiting the activation of NF-κB p65.

CONCLUSIONS

Our findings indicate that MHCD exert reno-protective effects in the experimental rat model of MN by alleviating podocyte damage and inhibiting the NF-κB pathway.

Evaluation of immunotherapy for idiopathic membranous nephropathy based on risk stratification and pathological stage

BACKGROUND

The treatment options for idiopathic membranous nephropathy (IMN) based on risk stratification and pathological staging unclear.

METHODS

This prospective cohort study included patients over 18 years of age with biopsy-proven, estimated glomerular filtration rate >50 mL/min/1.73 m2 IMN, as well as IMN patients at moderate and high risk according to the KDIGO guidelines, with pathological stages II and III, who were treated with tacrolimus (TAC), rituximab (RTX) or cyclophosphamide (CYC). Low-risk patients were divided into supportive care (SC) and non-SC (NSC) groups.

RESULTS

The incidence of complete remission (CR) was significantly greater in the TAC + glucocorticoids (GC) group than in the RTX and CYC + GC groups in the moderate-risk group at 12 months (P = 0.045). In the high-risk group, the CR rates were 48.0 %, 35.6 %, and 16.7 % in the TAC + GC, CYC + GC, and RTX groups, respectively (P < 0.001), and the average time to CR was the shortest in the TAC + GC group (P = 0.008). In stage II group, TAC + GC group had a higher CR rate and shorter average time to CR (P = 0.001, P = 0.015, respectively). At 6 months, the NSC group had significantly lower mean proteinuria compared to the SC group (P = 0.035), but the overall remission rates remained similar between both groups.

CONCLUSION

Compared with RTX and CYC + GC groups, TAC + GC group presented a greater rate of CR in moderate and high-risk groups, and had a greater incidence of CR and a shorter average time to CR in the stage II subgroup.

Efficacy and safety of rituximab for membranous nephropathy in adults: a meta-analysis of RCT

Background

Membranous nephropathy (MGN) represents a significant challenge in nephrology, with Rituximab emerging as a potential therapeutic intervention.

Methods

A comprehensive systematic review was conducted using PubMed, EMBASE, and Web of Science databases, focusing exclusively on randomized controlled trials (RCTs) from January 2002 to November 2024. Stringent eligibility criteria were applied, including studies with at least ten participants, with data extracted by two independent reviewers. The meta-analysis utilized fixed and random effects models to assess Rituximab's efficacy and safety across multiple outcome measures.

Results

The meta-analysis revealed nuanced findings across different follow-up periods. At 6 months, complete remission rates showed non-significant odds ratios ranging from 2.12 to 2.48. By 12 months, the pooled odds ratio was 0.8085 (95% CI: 0.2238-2.9213), with complete remission rates varying between 13.8% and 19.4%. Notably, at 24 months, the common effects model demonstrated a statistically significant odds ratio of 5.0792 (95% CI: 2.2609-11.4107, p < 0.0001). Proteinuria reduction showed consistent improvement, with a median difference of 4.3225. Adverse event analysis indicated a relatively low risk, with an odds ratio of 0.9706 (95% CI: 0.5781-1.6297).

Conclusion

Rituximab demonstrates potential efficacy in treating MGN, with promising long-term outcomes and a favorable adverse event profile.

Association of rituximab use with adverse events in adults with lymphoma or autoimmune disease: a single center experience

Objective

Rituximab (RTX) is a chimeric human/murine CD20 monoclonal antibody, which has been administered in treating hematological malignancies and various autoimmune disorders. This study aimed to present our center's experience in RTX use in adults with lymphoma and autoimmune diseases (AID) including primary membranous nephropathy (pMN), as well as therapeutic effects of RTX on clinical outcome of pMN patients.

Methods

A total of 761 Chinese patients were retrospectively included, who received RTX treatment at Shandong Provincial Hospital between January 1st, 2017 and December 31st, 2021, with person time of exposure spanning between their first dose of RTX and last follow-up date or the end of the study period.

Results

Adverse events (AEs) occurred in 487 patients (64.0%), with a majority of infection (309, 40.6%) and a minority of non-infectious AEs (178, 23.4%); and the incidences of AEs were higher in lymphoma patients (381, 65.8%) than that in AID patients (106, 58.2%). Respiratory infections (215, 28.3%), gastrointestinal infections (49, 6.4%), urinary tract infections (41, 5.4%), cutaneous and mucosal infections (31, 4.1%), and infections in the abdominal cavity or pleurisy (4, 0.5%) were the leading types of infections. Cancer diagnosis [hazard ratio (HR), 3.926; 95% confidence interval (CI), 1.730-8.913] and prophylactic sulfamethoxazole/trimethoprim (SMZ/TMP) administration (HR, 3.793; 95% CI, 1.101-13.069) were associated with increased risk of infections. Immediate non-infectious AEs included anaphylaxis (44, 5.8%) and infusion reactions (99, 13.0%). Long-term non-infectious AEs included hypogammaglobulinemia (106, 28.6%), neutropenia (11, 5.5%) and interstitial lung disease (1, 0.1%). Female sex (HR, 0.515; 95% CI, 0.289-0.918) and cancer diagnosis (HR, 0.126; 95% CI, 0.049-0.323) were associated with higher risk of hypogammaglobulinemia. In 74 pMN patients, 13 (17.6%) patients experienced infections, with 2 cases of non-infectious AEs (2.7%). 6-month follow-up showed remission was achieved in 45 patients (60.8%), either as initial (61.0%) or alternative therapy (60.7%), without significant impacts on kidney function (p > 0.05).

Conclusion

Our findings indicated AEs were common during RTX treatment, particularly in lymphoma patients, most of which were moderate and mild, highlighting a whole-process monitoring, timely interference and caring. And RTX was a safe and effective therapeutic option for pMN either as initial or alternative therapy in adult Chinese patients.

Telitacicept monotherapy for refractory idiopathic membranous nephropathy: a case report and literature review

Background

Patients with refractory membranous nephropathy (MN) face risks of progressive renal decline and end-stage renal disease (ESRD), with limited treatment efficacy. Telitacicept, a novel humanized recombinant fusion protein effective in lupus nephritis and immunoglobulin A nephropathy (IgAN), has few reports on its use in refractory MN.

Case presentation

In May 2023, an 82-year-old man was admitted to Shaoxing Second Hospital with bilateral lower extremity edema. A renal biopsy confirmed idiopathic membranous nephropathy (IMN). Standard therapies, including glucocorticoids (GC), cyclophosphamide (CYC), tacrolimus (TAC), and rituximab (RTX), were ineffective. He developed steroid-induced diabetes and acute renal failure during treatment. Complete proteinuria remission was achieved with telitacicept monotherapy. The patient is under ongoing clinical follow-up.

Conclusion

Telitacicept holds promise as a potential second-line therapy for refractory MN when conventional treatments prove ineffective. However, due to the current lack of robust evidence supporting its use in IMN, further research is warranted to establish its clinical efficacy and safety.

Artificial intelligence-based personalised rituximab treatment protocol in membranous nephropathy (iRITUX): protocol for a multicentre randomised control trial

INTRODUCTION

Membranous nephropathy is an autoimmune kidney disease and the most common cause of nephrotic syndrome in non-diabetic Caucasian adults. Rituximab is now recommended as first-line therapy for membranous nephropathy. However, Kidney Disease Improving Global Outcomes guidelines do not recommend any specific protocol. Rituximab bioavailability is reduced in patients with membranous nephropathy due to urinary drug loss. Underdosing of rituximab is associated with treatment failure. We have previously developed a machine learning algorithm to predict the risk of underdosing. We have retrospectively shown that patients with a high risk of underdosing required higher doses of rituximab to achieve remission. The aim of this prospective study is to evaluate the efficacy of algorithm-driven rituximab treatment in patients with membranous nephropathy compared to standard treatment.

METHODS

A multicentre, randomised, controlled, open-label, prospective superiority clinical trial will be conducted in 13 French hospitals. 130 consecutive patients with primary membranous nephropathy and active nephrotic syndrome will be randomised to either the standard protocol control group (two 1 g rituximab infusions on days 0 and 15) or the algorithm-driven rituximab treatment group. In the latter, the rituximab dose will depend on the algorithm-estimated risk of underdosing. Patients with an algorithm-estimated risk of underdosing ≤50% will receive 1 g of rituximab on days 0 and 15. Patients with an algorithm-estimated risk of underdosing between 51% and 75% will receive 1 g of rituximab on days 0, 15 and 30. Finally, patients with an estimated risk of underdosing >75% will receive 1 g of rituximab on days 0, 15, 30 and 45. The primary study outcome is the rate of clinical remission (complete or partial) at month 6 after treatment initiation. The secondary outcomes include clinical remission at month 12, immunological remission, proteinuria, albuminuria, serum creatinine, estimated glomerular filtration rate, phospholipase A2 receptor type 1 antibody titre, anti-rituximab antibody occurrence, lymphocyte count, serum rituximab level and related adverse events.

ETHICS AND DISSEMINATION

The trial received ethics approval from the local ethics boards. The results of this study will confirm whether algorithm-driven rituximab treatment is more effective in inducing remission than the standard regimen and thus may contribute to improving management of patients with membranous nephropathy. The results of our study will be submitted to a peer-review journal.

TRIAL REGISTRATION NUMBER

NCT06341205 trial number. Registered on 2 April 2024.

Comparison of the efficacy and impact on coagulation function of different rituximab dosage regimens in the treatment of membranous nephropathy

OBJECTIVE

To compare the efficacy and safety of two rituximab (RTX) dosage regimens - 1 g and 375 mg/m2 - in patients with idiopathic membranous nephropathy (IMN), focusing on their effects on coagulation function.

METHODS

We conducted a single-center, retrospective cohort study involving 323 IMN patients treated at Baoji High-Tech Hospital between May 1, 2022, and February 28, 2024. Patients were categorized into a standard-dose group (375 mg/m2, n=157) and a low-dose group (1 g, n=166) based on their RTX regimen. We compared clinical remission rates, relapse rates, adverse reactions, and changes in coagulation parameters (thrombin time [TT], prothrombin time [PT], fibrinogen [Fib]) between the groups.

RESULTS

Baseline characteristics, including age, gender, BMI, comorbidities, and immune indices, were similar between the groups (all P>0.05). Complete remission rates were 28.7% in the standard-dose group and 31.3% in the low-dose group, with overall response rates of 82.2% and 71.7%, respectively. Relapse rates were 19.1% and 19.3%, showing no significant differences (P>0.05). No significant differences in renal function, serum protein, urine protein, or PLA2R levels were observed between the groups (all P>0.05). Coagulation parameters remained unchanged before and after treatment (all P>0.05). Adverse reactions, including infections, infusion reactions, liver dysfunction, and gastrointestinal symptoms, occurred at similar rates in both groups (all P>0.05). Multivariate analysis identified BMI (OR=1.710, P<0.001), history of diabetes (OR=7.186, P=0.002), 24-hour urine protein at 6 months (OR=2.227, P<0.001), and PLA2R levels (OR=1.391, P<0.001) as independent risk factors for hypercoagulability.

CONCLUSION

Both 1 g and 375 mg/m2 RTX regimens exhibit comparable efficacy and safety in IMN patients, without significantly affecting coagulation function. Treatment should be individualized based on factors such as BMI, diabetes history, urine protein levels, and PLA2R levels to optimize coagulation risk management.

Obinutuzumab and Ofatumumab are More Effective Than Rituximab in the Treatment of Membranous Nephropathy Patients With Anti-Rituximab Antibodies

Introduction

Although rituximab has significantly improved outcomes for patients with membranous nephropathy, response to treatment is not universal and drug resistance can occur. One mechanism of resistance is the occurrence of antidrug antibodies. Obinutuzumab and ofatumumab are humanized and human monoclonal antibodies, respectively, that target B cells. These treatments have been shown to be effective in membranous nephropathy. However, obinutuzumab and ofatumumab have never been compared with rituximab in the treatment of patients with membranous nephropathy with anti-rituximab antibodies. We aimed to compare the efficacy and safety of obinutuzumab and ofatumumab with rituximab in patients with membranous nephropathy with anti-rituximab antibodies.

Methods

This international retrospective multicenter study enrolled 34 patients with membranous nephropathy from 5 nephrology departments in France, India, and Italy. All the patients had previously developed anti-rituximab antibodies. Nineteen patients received rituximab, 12 received obinutuzumab, and 3 received ofatumumab.

Results

Patients treated with obinutuzumab or ofatumumab were more likely to achieve clinical remission than those treated with rituximab at month 6 (87% vs. 37%, P = 0.005) and month 12 (87% vs. 42%, P = 0.01). Patients treated with obinutuzumab or ofatumumab were more likely to achieve immunological remission and B-cell depletion at month 6 than the patients treated with rituximab (92% vs. 56%, P = 0.04 and 93% vs. 35%, P = 0.002, respectively). No serious adverse events were reported in the obinutuzumab or ofatumumab group.

Conclusion

Obinutuzumab and ofatumumab are more effective than rituximab in treating patients with membranous nephropathy with anti-rituximab antibodies. Anti-rituximab antibodies should be systematically monitored, to determine appropriate treatment.

The role of obinutuzumab in rituximab-refractory membranous nephropathy and minimal change disease

Background

Obinutuzumab, a new-generation anti-CD20 monoclonal antibody, was originally developed to overcome resistance to rituximab in B-cell malignancies. There is limited research regarding the use of obinutuzumab in patients with rituximab-refractory membranous nephropathy (MN) and minimal change disease (MCD).

Methods

A retrospective analysis was performed at Changzheng Hospital from September 2022 to September 2024, and screened patients with rituximab-refractory MN or MCD. Participants were treated because they were refractory to rituximab and consented to receive infusions of obinutuzumab. Primary outcomes were defined as complete remission (CR, proteinuria <0.3 g/d) or partial remission (PR, proteinuria <3.5 g/d with a ≥50% reduction). Secondary outcome was immunological remission in patients with phospholipase A2 receptor (PLA2R)-related MN.

Results

Seven patients with MN and five with MCD were included in the cohort. Among patients with MN, six of seven (86%) achieved at least PR, of whom two patients reached CR with a median time to first remission (either PR or CR) of 8.0 months. Among patients with positive serum anti-PLA2R antibodies at baseline, all achieved an immunological response. No patients experienced a relapse during the follow-up period. Among patients with MCD, all patients achieved a CR with the median time of 1.0 months. Patients who were steroid-dependent or immunosuppressant-dependent were able to taper their medications in the short term without experiencing relapse. No treatment-related severe adverse events were reported.

Conclusions

Our study demonstrated that obinutuzumab represents a promising alternative therapeutic option for the management of rituximab-refractory MN and MCD.

Exploring the Role of TRAF6-TAK1 Pathway in Podocyte Pyroptosis and Its Implications for Primary Membranous Nephropathy Therapy

Primary membranous nephropathy (PMN) is a prevalent renal disorder characterized by immune-mediated damage to the glomerular basement membrane, with recent studies highlighting the significant role of pyroptosis in its progression. In this study, we investigate the molecular mechanisms underlying PMN, focusing on the role of Tumor necrosis factor receptor-associated factor 6 (TRAF6) in promoting disease advancement. Specifically, we examine how TRAF6 facilitates PMN progression by inducing the ubiquitination of Transforming growth factor-beta-activated kinase 1 (TAK1), which in turn activates the Gasdermin D (GSDMD)/Caspase-1 axis, leading to podocyte pyroptosis. Utilizing transcriptomic data from the gene expression omnibus database, we identified key regulatory factors involved in pyroptosis and validated these findings through the establishment of a C3a-induced podocyte injury model and a Sprague-Dawley (SD) rat model of PMN. Our findings reveal that TRAF6 is significantly upregulated in PMN, and its interaction with TAK1 is crucial for the activation of the GSDMD/Caspase-1 axis, ultimately driving podocyte pyroptosis. Further biochemical and molecular analyses confirmed the pivotal role of the TRAF6/TAK1 signaling pathway in the pathogenesis of PMN. These results underscore the importance of TRAF6-mediated signaling in the progression of PMN and suggest that targeting the TRAF6/TAK1/GSDMD/Caspase-1 axis may offer a novel therapeutic strategy for the treatment of this debilitating renal disease.

A bibliometric analysis from 2014 to 2024 reveals research hotspots and trends in the immunotherapy for glomerulonephritis

This study aimed to present an overview of the current status of research and important discoveries about immunotherapy for glomerulonephritis in general using bibliometric analysis. We collected the literature on immunotherapy for glomerulonephritis from the Web of Science (WOS) database for the last 10 years (2014-2024), and we assessed the mapping of knowledge using Citespace. The findings demonstrated that there were 258 articles concerning the immunotherapy for glomerulonephritis, with a faster growth after 2018. The USA, Charite Universitatsmedizin Berlin, and Anders, Hans-Joachim are the nation, organization, and writer with the highest number of publications. The most often cited reference is Rovin BH (2021) as well (5). The best partnerships are formed by prestigious universities and developed countries for glomerulonephritis research on immunotherapy. Three research hotspots in this area are rituximab, adjuvant, and antibody production erythematosus, respectively.

Different Dosage Regimens of Rituximab in Primary Membranous Nephropathy Treatment: A Systematic Review

Primary membranous nephropathy (PMN) is one of the prevalent pathological types of adult primary nephrotic syndrome. Pathogenic autoantibodies targeting podocyte antigens such as phospholipase A2 receptor (PLA2R) lead to the disease. Patients frequently experience notable adverse effects when treated with conventional immunosuppressive therapies. Rituximab (RTX), a mouse/human monoclonal antibody, selectively depletes B cells and leads to a decrease in the antibody levels in the circulation, which helps to alleviate membranous nephropathy. Various RTX dosage regimens have been applied globally in the PMN treatment with satisfactory effects. Nevertheless, the optimal dosage of RTX has yet to be determined. This article reviews the application of different doses of RTX in the management of PMN so far.

B cell dysregulation and depletion therapy in primary membranous nephropathy: Prospects and potential challenges

B cells are crucial to the humoral immune response, originating in the bone marrow and maturing in the spleen and lymph nodes. They primarily function to protect against a wide range of infections through the secretion of antibodies. The role of B cells in primary membranous nephropathy (PMN) has gained significant attention, especially following the discovery of various autoantibodies that target podocyte antigens and the observed positive outcomes from B cell depletion therapy. Increasing evidence points to the presence of abnormal B cell subsets and functions in MN. B cells have varied roles during the different stages of disease onset, progression, and relapse. Initially, B cells facilitate self-antigen presentation, activate effector T cells, and initiate cellular immunity. Subsequently, the disruption of both central and peripheral immune tolerance results in the emergence of autoreactive B cells, with strong germinal center responses as a major source of MN autoantibodies. Additionally, critical B cell subsets, including Bregs, memory B cells, and plasma cells, play roles in the immune dysregulation observed in MN, assisting in predicting disease recurrence and guiding management strategies for MN. This review offers a detailed overview of research advancements on B cells and elucidates their pathological roles in MN.

TFAB002s, novel CD20-targeting T cell-dependent bispecific Fab-FabCH3 antibodies, exhibit potent antitumor efficacy against malignant B-cell lymphoma

B-cell lymphoma, clinically, comprises a heterogeneous group of malignancies that encompass various subtypes. CD20 is an optimal target for therapeutic antibodies in B-cell lymphoma immunotherapy since approximately 90% of B-cell malignancies typically exhibit CD20 expression on their surface, while its presence is limited in normal tissues. In this study, we have developed a series of novel non-IgG-like T cell-dependent bispecific antibodies by constructing Fab-FabCH3, referred to as Tandem Antigen-binding Fragment 002 (TFAB002), which specifically target CD20 for the treatment of malignant B-cell lymphoma. TFAB002s display strong binding affinity with CD20 and moderate binding affinity with CD3, thereby triggering target-specific T-cell activation, cytokine release, and tumor cell lysis in vitro. Furthermore, TFAB002s exhibit potent cytotoxicity against B-cell malignancies that express varying levels of CD20. Besides, the TFAB002s show potent pharmacodynamic activity in vivo in the WIL2-S cells CDX mouse model. Collectively, these results underscore the potential of TFAB002s as a highly promising therapeutic approach for selectively depleting CD20-positive B cells, thereby warranting further clinical evaluation as a viable treatment option for CD20-expressing B-cell malignancies.

Case report: Effective treatment of rituximab-resistant minimal change disease with obinutuzumab in an adult

Background

Minimal change disease (MCD) is a common cause of adult nephrotic syndrome. Most adults with MCD achieve complete remission (CR) after initial steroid therapy. However, approximately 30% of adults who respond to steroids experience frequent relapses, becoming steroid-dependent and potentially developing refractory MCD. Treating refractory MCD in adults poses a significant challenge.

Main body

A 37-year-old woman presented to the nephrology department with a 6-year history of MCD. The diagnosis of MCD was confirmed via renal biopsy. She initially achieved CR with steroid treatment but experienced relapse during steroid tapering. Subsequent CR was achieved with a regimen of steroids and tacrolimus although multiple relapses occurred. Rituximab led to another CR, but its maintenance lasted only 6 months. The response to subsequent rituximab treatments was unsatisfactory. Ultimately, obinutuzumab was selected, resulting in the induction and maintenance of CR for 12 months.

Conclusions

This case demonstrates the successful treatment of frequently relapsed, steroid-dependent, and rituximab-resistant MCD with obinutuzumab. Obinutuzumab is a promising therapeutic option for rituximab-resistant MCD.

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.

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.

A Policy Call to Address Rare Kidney Disease in Health Care Plans

Despite a large number of people globally being affected by rare kidney diseases, research support and health care policy programs usually focus on the management of the broad spectrum of CKD without particular attention to rare causes that would require a targeted approach for proper cure. Hence, specific curative approaches for rare kidney diseases are scarce, and these diseases are not treated optimally, with implications on the patients' health and quality of life, on the cost for the health care system, and society. There is therefore a need for rare kidney diseases and their mechanisms to receive the appropriate scientific, political, and policy attention to develop specific corrective approaches. A wide range of policies are required to address the various challenges that target care for rare kidney diseases, including the need to increase awareness, improve and accelerate diagnosis, support and implement therapeutic advances, and inform the management of the diseases. In this article, we provide specific policy recommendations to address the challenges hindering the provision of targeted care for rare kidney diseases, focusing on awareness and prioritization, diagnosis, management, and therapeutic innovation. In combination, the recommendations provide a holistic approach aiming for all aspects of rare kidney disease care to improve health outcomes, reduce the economic effect, and deliver benefits to society. Greater commitment from all the key stakeholders is now needed, and a central role should be assigned to patients with rare kidney disease to partner in the design and implementation of potential solutions.

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.

Hypokalemia after rituximab administration in nephrotic syndrome: two case reports

Rituximab, a chimeric anti-CD20 monoclonal antibody, is an effective treatment for nephrotic syndrome. Hypokalemia is a rare adverse reaction among patients treated with rituximab although there have been extensive reports of acute and chronic adverse events with the administration of rituximab. We herein report two cases of symptomatic hypokalemia after intravenous rituximab administration in our center, to help health professionals consider the possibility of acute hypokalemia after rituximab administration, monitor potassium timely and develop an appropriate treatment plan.

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.

Comparative analysis of the efficacy of different treatments for idiopathic membranous nephropathy: a retrospectively real-world study

BACKGROUND

This study aimed to explore the clinical efficacy of different treatment regimens for idiopathic membranous nephropathy (IMN).

METHODS

Patients with IMN were retrospectively analyzed by dividing into two groups: glucocorticoids combined with cyclophosphamide group (GC + CYC) and glucocorticoids combined with calcineurin inhibitor group (GC + CNIs). After 1 year of treatment, those who found that the initial treatment was not effective were switched to another regimen. Patients continued to be followed up for at least 1 year to observe the treatment effects of different treatment regimens.

RESULTS

This study found that the rate of complete and partial remission (CR + PR) in the GC + CYC and GC + CNIs groups was 76.19 vs. 82.63% after 1 year of follow-up (p > .05). In the GC + CYC and GC + CNIs groups, 27.78 and 11.95% of the patients switched treatment regimens, respectively. After 2 years of follow-up, the CR + PR rate was significantly higher in the change to GC + CNIs group after the switch compared to before the switch (80.00 vs. 31.43%, p < .001). It was also significantly higher in the change to GC + CYC group compared to before the switch (68.42 vs. 31.58%, p = .023). The recurrence rate was significantly higher in the maintain GC + CNIs and change to GC + CNIs groups than in the maintain GC + CYC and change to GC + CYC groups (25.14 vs 6.36%, p < .001). The disengagement rate from immunotherapy was significantly higher in the maintain GC + CYC group and the change to GC + CYC group than in the maintain GC + CNIs group and the change to GC + CNIs group (76.36% vs 29.71%, p < .001). High titer of anti-phospholipase A2 receptor (anti-PLA2R) antibody (95%CI: 0.199-0.947, p = .036) and serum C3 (95%CI: 0.030-0.570, p = .007) were independent risk factors, while serum IgG (95%CI: 1.000-1.331, p = .050) was a favorable factor for achieving CR. Anti-PLA2R antibody was the independent risk factor that affected the worse renal condition (p = .023).

CONCLUSIONS

Timely change of treatment regimen can significantly enhance therapeutic effect. Compared with patients administered with CYC, those administered with CNIs were less likely to leave treatment and had a higher recurrence rate.

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.

Successful treatment of patients with refractory idiopathic membranous nephropathy with low-dose Rituximab: A single-center experience

BACKGROUND

The recognition of idiopathic membranous nephropathy (IMN) as an autoimmune disease has paved the way for the use of B-cell-depleting agents, such as Rituximab (RTX), which is now a first-line drug for treating IMN with proven safety and efficacy. Nevertheless, the usage of RTX for the treatment of refractory IMN remains controversial and challenging.

AIM

To evaluate the efficacy and safety of a new low-dose RTX regimen for the treatment of patients with refractory IMN.

METHODS

A retrospective study was performed on refractory IMN patients that accepted a low-dose RTX regimen (RTX, 200 mg, once a month for five months) in the Xiyuan Hospital of Chinese Academy of Chinese Medical Sciences’ Department of Nephrology from October 2019 to December 2021. To assess the clinical and immune remission data, we performed a 24 h urinary protein quantification (UTP) test and measured the serum albumin (ALB) and serum creatinine (SCr) levels, phospholipase A2 receptor (PLA2R) antibody titer, and CD19⁺ B-cell count every three months.

RESULTS

A total of nine refractory IMN patients were analyzed. During follow-up conducted twelve months later, the results from the 24 h UTP decreased from baseline [8.14 ± 6.05 g/d to 1.24 ± 1.34 g/d (P < 0.05)] and the ALB levels increased from baseline [28.06 ± 8.42 g/L to 40.93 ± 5.85 g/L (P < 0.01)]. Notably, after administering RTX for six months, the SCr decreased from 78.13 ± 16.49 μmol/L to 109.67 ± 40.87 μmol/L (P < 0.05). All of the nine patients were positive for serum anti-PLA2R at the beginning, and four patients had normal anti-PLA2R titer levels at six months. The level of CD19⁺ B-cells decreased to 0 at three months, and CD19⁺ B-cell count remained at 0 up until six months of follow-up.

CONCLUSION

Our low-dose RTX regimen appears to be a promising treatment strategy for refractory IMN.

The role of the complement system in primary membranous nephropathy: A narrative review in the era of new therapeutic targets

Primary membranous nephropathy (MN) is an important cause of nephrotic syndrome and chronic kidney disease (CKD) in the adult population. Although the discovery of different autoantibodies against glomerular/podocytic antigens have highlighted the role of B cells in the pathogenesis of MN, suboptimal response or even resistance to B cell-directed therapies occurs, suggesting that other pathophysiological mechanisms are involved in mediating podocyte injury. The complement system plays an important role in the innate immune response to infection, and dysregulation of the complement system has been observed in various kidney diseases. There is compelling evidence of complement cascade activation in primary MN, with the mannose-binding lectin (MBL) and alternative pathways particularly implicated. With appropriate validation, assays of complements and associated activation products could hold promise as adjunctive tools for non-invasive disease monitoring and prognostication. While there is growing interest to target the complement system in MN, there is concern regarding the risk of infection due to encapsulated organisms and high treatment costs, highlighting the need for clinical trials to identify patients most likely to benefit from complement-directed therapies.

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.