Anti-PLA2R Antibody Levels and Clinical Risk Factors for Treatment Nonresponse in Membranous Nephropathy

Designing clinical trials for the treatment of membranous nephropathy in the anti-PLA2R era: results of a Nephcure membranous nephropathy workshop

Primary membranous nephropathy is a common cause of adult-onset nephrotic syndrome, with an overall incidence of 12 cases per million per year. Primary membranous nephropathy is an autoimmune kidney disease; however, primary membranous nephropathy autoantigens remained elusive until 2009 when the M-type phospholipase A2 receptor 1 (PLA2R) was identified as a disease autoantigen. This was followed relatively rapidly by identification of several other autoantigens. Autoantibodies against PLA2R are detectable in ≈75% of patients with primary membranous nephropathy. The discovery of circulating and deposited autoantibodies against PLA2R offers an opportunity in nephrology to personalize disease management. On January 14, 2023, Nephcure Kidney International convened a scientific workshop in Arlington, Virginia, to discuss the state of the science on autoantibodies against PLA2R and considerations related to the incorporation of autoantibodies against PLA2R in drug development programs for membranous nephropathy. The present report captures the discussion that occurred at the Membranous Nephropathy Scientific Workshop.

Membranous Nephropathy

Membranous nephropathy is a glomerular disease that may be caused by exogenous risk factors in genetically predisposed individuals (primary MN) or may be associated with other autoimmune diseases, drug exposure, or cytotoxic agents (secondary MN). Primary membranous nephropathy (PMN) is an autoimmune disease in which antigens-mainly the phospholipase A2 receptor-are located in the podocytes and are targeted by circulating antibodies, leading to in situ formation of immune complexes that activate the complement system. Clinically, the disease is characterized by nephrotic syndrome (NS) and associated complications. The outcome of PMN can vary, but untreated patients with NS may progress to end-stage kidney disease (ESKD) in 35-40% of cases within 10 years. Treatment primarily aims to prevent NS complications and progression to ESKD. The most commonly used immunosuppressive drugs are rituximab, corticosteroids, cyclophosphamide, and calcineurin inhibitors. Most patients may experience an improvement of proteinuria, which can sometimes be followed by NS relapse. Fewer than 50% of patients with PMN achieve complete and stable remission. In addition to immunosuppressive therapy, antiproteinuric, anti-lipemic, and anticoagulant medicaments are often required.

Updated diagnostic and therapeutic management for membranous nephropathy

PURPOSE OF REVIEW

Pioneering contributions in membranous nephropathy over the last decade have greatly enhanced our comprehension of its pathogenesis, diagnosis, and treatments, igniting renewed interest in this entity. This review provides an updated perspective on the diagnosis and therapeutic management of membranous nephropathy.

RECENT FINDINGS

The identification of antiphospholipase A2 receptor (PLA2R) antibodies in 50-80% of membranous nephropathy patients was a key breakthrough. High or increasing PLA2R antibody levels are linked to persistent nephrotic syndrome and the need for targeted treatment. Given the high specificity of PLA2R antibodies, a kidney biopsy may not be required for pure nephrotic syndrome cases with no comorbidities. Over the years, various target antigens and associated conditions have been identified in membranous nephropathy patients, leading to a reclassification of membranous nephropathy. Treatment approaches vary based on baseline characteristics and changes in proteinuria and PLA2R titers. Rituximab has emerged as the first-line therapy for most patients without severe risk factors, with other emerging therapies under development.

SUMMARY

Advances in the diagnosis and treatment of membranous nephropathy have moved the management towards a more precision-based approach, though further studies and new therapies are needed for a comprehensive management strategy.

Designing Clinical Trials for the Treatment of Membranous Nephropathy in the Anti-Phospholipase A2 Receptor 1 Era: Results of a NephCure Membranous Nephropathy Workshop

Primary membranous nephropathy is a common cause of adult-onset nephrotic syndrome, with an overall incidence of 12 cases per million per year. Primary membranous nephropathy is an autoimmune kidney disease; however, primary membranous nephropathy autoantigens remained elusive until 2009, when the M-type phospholipase A2 receptor 1 (PLA2R) was identified as a disease autoantigen. This was followed relatively rapidly by the identification of several other autoantigens. Autoantibodies against PLA2R are detectable in ≈75% of patients with primary membranous nephropathy. The discovery of circulating and deposited autoantibodies against PLA2R offers an opportunity in nephrology to personalize disease management. On January 14, 2023, NephCure Kidney International convened a scientific workshop in Arlington, Virginia, to discuss the state of the science on autoantibodies against PLA2R and considerations related to the incorporation of autoantibodies against PLA2R in drug development programs for membranous nephropathy. The present report captures the discussion that occurred at the Membranous Nephropathy Scientific Workshop.

A novel approach to induce early remission in high-risk primary membranous nephropathy

BACKGROUND

This prospective single-arm trial with historic controls evaluated the efficacy and safety of treatment based on a combination of rituximab, intravenous cyclophosphamide and corticosteroids (RCP) administered at lower cumulative doses for the induction of early remission in primary membranous nephropathy (PMN).

METHODS

We prospectively enrolled 30 high-risk PMN patients with persistent nephrotic syndrome (NS) and elevated antibodies to the phospholipase A2 receptor who underwent RCP therapy. We compared the effectiveness of RCP with that of historic controls who received rituximab-based therapy (RTX, n = 15) or cyclosporine + corticosteroids (CSA, n = 42). The primary outcomes were complete remission (CR) and overall remission (OR) by Month 12 and the time to remission.

RESULTS

In the RCP group, the OR and CR rates by 12 months (97% and 60%) were higher than those in the RTX group (60% and 7%, P ≤ .009) and the CSA group (50% and 24%, P ≤ .003). The median time to OR [2.8 (1.6-3.9) months] was shorter compared with RTX [7.1 (3.4-17.5) months, P = .008] and CSA [7.3 (6.0-13.6) months, P < .001]. In adjusted Cox regression, hazard ratios for OR and CR attainment for RCP versus other treatments were 5.2 (95% CI 2.8-9.6) and 4.8 (95% CI 2.2-10.3), respectively. Propensity score-matched group analyses confirmed these results. One serious adverse event occurred in the RCP group in the follow-up of 56 patient-years.

CONCLUSIONS

RCP therapy is considered effective and safe for inducing early remission in high-risk PMN patients.

Combination Therapy With Rituximab and Low-Dose Cyclophosphamide and Prednisone in Membranous Nephropathy

Introduction

Standard treatment with cyclophosphamide (CP) or rituximab (RTX) is suboptimal. We adapted and used the low-dose regimen used in vasculitis (RTX 2 × 1000 mg, CP 1.5 mg/kg/d × 8 weeks, and prednisone [i.v. 2 × 1 g + 3 weeks oral starting at 1 mg/kg]).

Methods

High-risk, anti-PLA2R antibodies (PLA2Rab)-positive patients with membranous nephropathy (MN) were included in this single-arm prospective cohort study. PLA2Rab levels were regularly measured. We report the PLA2Rab kinetics and overall immunological and clinical remission (CR) rate.

Results

We analyzed 26 patients (15 males, aged 57 ± 14 years, PLA2Rab titer 176 [115-460] RU/ml, serum creatinine 128 [102-136] μmol/l, serum albumin 18 [14-21] g/l, and urinary protein-to-creatinine ratio [uPCR] 7.1 [5.7-10] g/10 mmol). Within 8 weeks immunological remission (IR) (enzyme-linked immunosorbent assay < 14 RU/ml) was 88 %. Proteinuria remission after initial therapy developed in 21 patients. Seven patients received renewed therapy, which resulted in proteinuria remission in all. IR and CR were associated with baseline PLA2Rab tertile. Five of 7 patients in need of additional therapy were identified at 4 weeks after start of therapy by PLA2Rab half-life (T1/2) > 7 days. Serious adverse events occurred in 4 patients. Adverse events were mild; leukopenia was most frequent.

Conclusion

Low-dose triple therapy induced a rapid IR and CR in most patients. Patients with insufficient clinical response were characterized by high baseline PLA2Rab levels and longer PLA2Rab T1/2. Assessment of PLA2Rab levels within 2 to 4 weeks after start of therapy may enable to identify patients who need more intensive therapy.

Pilot Trial of Hydroxychloroquine as Add-On Therapy in Patients With Membranous Nephropathy

Introduction

Kidney Disease Improving Global Outcomes guidelines indicate that glucocorticoids and immunosuppressants comprise the first therapeutic regimens after 4 to 6 months of treatment for high-risk primary membranous nephropathy (PMN). However, some patients cannot achieve complete or partial remission at 6 months. This study aimed to evaluate the efficacy of traditional immunotherapy combined with hydroxychloroquine (HCQ), a well-known immune regulator, in patients with PMN.

Methods

This was a single-center, open-label, prospective study. We recruited 72 patients with nephrotic syndrome and PMN proven by renal biopsy from May 2020 to June 2024. We compared changes in proteinuria, serum albumin levels, estimated glomerular filtration rate (eGFR), and relapse rate at 3, 6, 9, and 12 months follow-up in 41 patients who received glucocorticoid and immunosuppressant, and in 31 who received HCQ plus standard-of-care.

Results

Baseline characteristics showed no statistical significance between the 2 groups. However, the HCQ group showed significantly reduced proteinuria compared to standard-of-care group. A reduced proteinuria was seen at 6 months (1.2 [0.4-2.2] vs. 2.2 [1.0-3.8] g/d, P = 0.029) and the relapse rate with 12 months follow-up was also significantly decreased in the HCQ group compared to the standard-of-care group (3.7% vs. 23.3%, P = 0.033).

Conclusions

HCQ may serve as an effective add-on therapy for PMN.

Rituximab or cyclosporine A for the treatment of membranous nephropathy: economic evaluation of the MENTOR trial

BACKGROUND AND HYPOTHESIS

The MENTOR trial (MEmbranous Nephropathy Trial Of Rituximab) showed that rituximab was noninferior to cyclosporine in inducing complete or partial remission of proteinuria and was superior in maintaining proteinuria remission. However, the cost of rituximab may prohibit first-line use for some patients and health-care payers.

METHODS

A Markov model was used to determine the incremental cost-effectiveness ratio (ICER) of rituximab compared with cyclosporine for the treatment membranous nephropathy from the perspective of a health-care payer with a lifetime time horizon. The model was informed by data from the MENTOR trial where possible; additional parameters including cost and utility inputs were obtained from the literature. Sensitivity analyses were performed to evaluate the impact of reduced-cost biosimilar rituximab.

RESULTS

Rituximab for the treatment of membranous nephropathy was cost effective (assuming a willingness-to-pay threshold of $50 000 per quality-adjusted life year (QALY) gained; in $US 2021) compared with cyclosporine, with an ICER of $8373/QALY over a lifetime time horizon. The incremental cost of rituximab therapy was $28 007 with an additional 3.34 QALYs compared with cyclosporine. Lower cost of rituximab biosimilars resulted in a more favorable ICER, and in some cases resulted in rituximab being dominant (lower cost and great benefit) compared to cyclosporine.

CONCLUSIONS

Despite the greater cost of rituximab, it may be a cost-effective option for the treatment of membranous nephropathy when compared with cyclosporine. The cost-effectiveness of rituximab is further improved with the use of less expensive biosimilars.

Prediction model for treatment response of primary membranous nephropathy with nephrotic syndrome

OBJECTIVE

To investigate the predictors and establish a nomogram model for the prediction of the response to treatment in primary membranous nephropathy (PMN) with nephrotic syndrome (NS).

METHODS

The clinical, laboratory, pathological and follow-up data of patients with biopsy-proven membranous nephropathy at the Affiliated Hospital of Qingdao University were collected. A total of 373 patients were randomly assigned into development group (n = 262) and validation group (n = 111). Logistic regression analysis was performed in the development group to determine the predictors of treatment response. A nomogram model was established based on the multivariate logistic regression analysis and validated in the validation group. The C-index and calibration plots were used for the evaluation of the discrimination and calibration performance, respectively.

RESULTS

Serum albumin levels (OR = 1.151, 95% CI 1.078-1.229, P < 0.001) and glomerular C3 deposition (OR = 0.407, 95% CI 0.213-0.775, P = 0.004) were identified as independent predictive factors for treatment response in PMN with NS, then a nomogram was established combining the above indicators and treatment regimen. The C-indices of this model were 0.718 (95% CI 0.654-0.782) and 0.789 (95% CI 0.705-0.873) in the development and validation groups, respectively. The calibration plots showed that the predicted probabilities of the model were consistent with the actual probabilities (P > 0.05), which indicated favorable performance of this model in predicting the treatment response probability.

CONCLUSIONS

Serum albumin levels and glomerular C3 deposition were predictors for treatment response of PMN with NS. A novel nomogram model with good discrimination and calibration was constructed to predict treatment response probability at an early stage.

Membranous Nephropathy: Updates on Management

Membranous nephropathy is a major etiology of nephrotic syndrome in adults and less frequently in children. Circulating antibodies to intrinsic podocyte antigens, such as M-type phospholipase A2 receptor, or to extrinsic proteins accumulate beneath the podocyte to cause damage via complement activation and/or other mechanisms. The availability of clinical testing for autoantibodies to M-type phospholipase A2 receptor has allowed noninvasive diagnosis of this form of membranous nephropathy and a means to monitor immunologic activity to guide immunosuppressive therapy. Treatment of membranous nephropathy includes optimal supportive care with renin-angiotensin-system blockers, lipid-lowering agents, diuretics, lifestyle changes, and additional immunosuppressive therapy in patients with an increased risk of progression to kidney failure. Rituximab has been recognized as a first-line immunosuppressive therapy for most membranous nephropathy patients with an increased risk of progressive disease, except those with life-threatening nephrotic syndrome or rapidly deteriorating kidney function from membranous nephropathy. This article discusses the major and minor antigens described in membranous nephropathy, the natural history of the disease, and guidelines for clinical management and immunosuppressive treatment.

Membranous nephropathy: pathogenesis and treatments

Membranous nephropathy (MN), an autoimmune disease, can manifest at any age and is among the most common causes of nephrotic syndrome in adults. In 80% of cases, the specific etiology of MN remains unknown, while the remaining cases are linked to drug use or underlying conditions like systemic lupus erythematosus, hepatitis B virus, or malignancy. Although about one-third of patients may achieve spontaneous complete or partial remission with conservative management, another third face an elevated risk of disease progression, potentially leading to end-stage renal disease within 10 years. The identification of phospholipase A2 receptor as the primary target antigen in MN has brought about a significant shift in disease management and monitoring. This review explores recent advancements in the pathophysiology of MN, encompassing pathogenesis, clinical presentations, diagnostic criteria, treatment options, and prognosis, with a focus on emerging developments in pathogenesis and therapeutic strategies aimed at halting disease progression. By synthesizing the latest research findings and clinical insights, this review seeks to contribute to the ongoing efforts to enhance our understanding and management of this challenging autoimmune disorder.

Ten tips on immunosuppression in primary membranous nephropathy

Membranous nephropathy (MN) management poses challenges, particularly in selecting appropriate immunosuppressive treatments (IST) and monitoring disease progression and complications. This article highlights 10 key tips for the management of primary MN based on current evidence and clinical experience. First, we advise against prescribing IST to patients without nephrotic syndrome (NS), emphasizing the need for close monitoring of disease progression. Second, we recommend initiating IST in patients with persistent NS or declining kidney function. Third, we suggest prescribing rituximab (RTX) or RTX combined with calcineurin inhibitors in medium-risk patients. Fourth, we propose cyclophosphamide-based immunosuppression for high-risk patients. Fifth, we discourage the use of glucocorticoid monotherapy or mycophenolate mofetil as initial treatments. Sixth, we underscore the importance of preventing infectious complications in patients receiving IST. Seventh, we emphasize the need for personalized monitoring of IST by closely measuring kidney function, proteinuria, serum albumin and anti-M-type phospholipase A2 receptor levels. Eighth, we recommend a stepwise approach in the treatment of resistant disease. Ninth, we advise adjusting treatment for relapses based on individual risk profiles. Finally, we caution about the potential recurrence of MN after kidney transplantation and suggest appropriate monitoring and treatment strategies for post-transplantation MN. These tips provide comprehensive guidance for clinicians managing MN, aiming to optimize patient outcomes and minimize complications.

Membranous nephropathy treatment standard

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