Rituximab for Idiopathic Membranous Nephropathy: Who Can Benefit?

Novel approaches to primary membranous nephropathy: Beyond the KDIGO guidelines

Primary membranous nephropathy (PMN) is an immune-mediated glomerular disease. Rituximab (RTX) is recommended as a first-line immunosuppressive therapy and shows high clinical efficacy, but the optimal doses remain controversial. Approximately 20%-40% of PMN patients experience RTX resistance and failure. Reduced bioavailability, RTX internalization and attack, anti-RTX antibody production, autoreactive B-cell reservoirs and chronic and irreversible renal damage may contribute to this problem. Therefore, new treatment modalities are needed to compensate for this deficit. New interventions and new dose combinations are being proposed. Multiple drug combination therapies show comparable clinical efficacy to conventional treatments by blocking the production of disease-causing antibodies in multiple directions, and can reduce single-agent doses without increasing adverse effects. New therapies that directly target B cells, plasma cells, and antibody production have shown encouraging results. In addition, new techniques for sweeping antibodies and chimeric antigen receptor T-cell therapy also may be promising strategies for PMN. Immunoadsorption could be used as an auxiliary choice for severe cases. This article explores new treatments for PMN and highlights possible mechanisms for potential new technologies that offer new ideas for treatment.

Significance of the total renal chronicity score in predicting renal outcome in PLA2R-associated membranous nephropathy

BACKGROUND

Phospholipase A2 receptor (PLA2R)-associated membranous nephropathy accounts for the majority of membranous nephropathy; however, few studies have determined the prognostic impact and clinical application of renal pathologic change on this disease.

METHODS

A retrospective cohort study of 262 patients with PLA2R-associated membranous nephropathy was conducted. The total renal chronicity score calculated according to the degree of glomerulosclerosis, interstitial fibrosis, tubular atrophy, and arteriosclerosis was applied to evaluate renal chronicity. Baseline bias was adjusted by inverse probability weight when assessing the prognostic impact of chronicity, and multiple parameters were used to evaluate the application value of renal chronicity.

RESULTS

During a median follow-up of 24.5 months, renal outcome (kidney function deterioration and/or end-stage kidney disease) was observed in 22 (8.40%) patients. Not only did a higher total renal chronicity score independently predict renal outcome [odds ratio (OR): 1.562, 95% confidence interval (CI) 1.073-2.273, P = 0.020], but non-minimal chronicity was also an independent risk factor for renal outcome (OR: 3.170, 95% CI 1.040-9.659, P = 0.042). Moreover, the membranous nephropathy risk classification in the Kidney Disease: Improving Global Outcomes (KDIGO) guideline integrated with non-minimal chronicity showed improvements in categorical net reclassification (0.174, 95% CI 0.012-0.335, P = 0.035), continuous net reclassification (0.462, 95% CI 0.087-0.838, P = 0.016), and integrated discrimination (0.019, 95% CI 0.003-0.035, P = 0.020) compared to the original classification.

CONCLUSIONS

Renal chronicity is closely associated with renal outcomes in PLA2R-associated membranous nephropathy, and combining the KDIGO risk classification with chronicity scores may provide a more accurate prognostic prediction.

An Updated Review of Membranous Nephropathy

Membranous nephropathy (MN) is one of the most common causes of nephrotic syndrome in adults. The discovery of phospholipase A2 receptor (PLA2R) as a target antigen has led to a paradigm shift in the understanding and management of MN. At present, serum PLA2R antibodies are used for diagnosis, prognostication, and guiding treatment. Now, with the discovery of more than 20 novel target antigens, antigen mapping is almost complete. The clinical association of certain antigens provides clues for clinicians, such as the association of nerve epidermal growth factor-like 1 with malignancies and indigenous medicines. Serum antibodies are detected for most target antigens, except exostosin 1 and 2 and transforming growth factor-beta receptor 3, but their clinical utility is yet to be defined. Genome-wide association studies and studies investigating environmental factors, such as air pollution, shed more light on the underpinnings of MN. The standard therapy of MN diversified from cyclical cyclophosphamide and steroids to include rituximab and calcineurin inhibitors over the past decades. Here, we provide a cutting-edge review of MN, focusing on genetics, immune system and environmental factors, novel target antigens and their clinical characteristics, and currently available and emerging novel therapies in MN.

Rituximab, Use and B Cell Depletion in Patients with Membranous Nephropathy- A Retrospective, Observational Study

Introduction

Rituximab (Rtx), an anti-CD20 monoclonal antibody, results in selective B-cell depletion and has emerged as an important therapeutic option in idiopathic membranous nephropathy (MN). We conducted a retrospective observational study to evaluate the efficacy and tolerability of Rtx in MN with respect to the B-cell count depletion.

Methods

Twenty patients with biopsy proven primary MN, both treatment naïve and treatment resistant, who received a fixed dose protocol of 500mg IV Rtx 1month apart were retrospectively observed with a minimum follow-up period of 12 months. The primary clinical outcome was complete (CR) or partial remission (PR) at 12 months in relation to B-cell depletion at 6 and 12 months.

Results

All were patients (men, 90%) of PLA2R-Ab positive with MN with a mean age of 37.7 ± 12.5 years. The mean 24-h urinary protein was 7.5 ± 2.15 gm/day, serum albumin was 2.01 ± 0.6gm/dL, and eGFR was 86.5 ± 20 mL/min/1.73m2. Primary composite outcome at 12 months was 66.7%, with 5.6% CR and 61.1% PR.The mean PLA2R-Ab at 12 months was low in those with remission compared to those who did not achieve (17.8 ± 21.2 RU/mL vs 311.7 ± 356.0; P = 0.01). Sustained B cell depletion at 6 months was seen in 84.3% (OR = 2.2, 95% CI = 0.11-42.7; P = 0.53) and 32% at 12 months (OR = 2.25, 95% CI = 0.18-27.7, and P = 0.66).

Conclusion

Acceptable remission rates were seen with Rtx in both treatment naïve and treatment-resistant patients with MN. There was no significant association between B-cell depletion and remission.

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 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.

Membranous nephropathy: new pathogenic mechanisms and their clinical implications

Membranous nephropathy (MN) is characterized histomorphologically by the presence of immune deposits in the subepithelial space of the glomerular filtration barrier; its clinical hallmarks are nephrotic range proteinuria with oedema. In patients with primary MN, autoimmunity is driven by circulating autoantibodies that bind to one or more antigens on the surface of glomerular podocytes. Compared with other autoimmune kidney diseases, the understanding of the pathogenesis of MN has substantially improved in the past decade, thanks to the discovery of pathogenic circulating autoantibodies against phospholipase A₂ receptor 1 (PLA₂R1) and thrombospondin type 1 domain-containing protein 7A (THSD7A). The subsequent identification of more proteins associated with MN, some of which are also endogenous podocyte antigens, might further advance the clinical characterization of MN, including its diagnosis, treatment and prognosis. Insights from studies in patients with MN, combined with the development of novel in vivo and in vitro experimental models, have potential to improve the management of patients with MN. Characterizing the interaction between autoimmunity and local glomerular lesions provides an opportunity to develop more specific, pathogenesis-based treatments.

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.

Immunosuppressive treatment for primary membranous nephropathy in adults with nephrotic syndrome

BACKGROUND

Primary membranous nephropathy (PMN) is a common cause of nephrotic syndrome in adults. Without treatment, approximately 30% of patients will experience spontaneous remission and one third will have persistent proteinuria. Approximately one-third of patients progress toward end-stage kidney disease (ESKD) within 10 years. Immunosuppressive treatment aims to protect kidney function and is recommended for patients who do not show improvement of proteinuria by supportive therapy, and for patients with severe nephrotic syndrome at presentation due to the high risk of developing ESKD. The efficacy and safety of different immunosuppressive regimens are unclear. This is an update of a Cochrane review, first published in 2004 and updated in 2013.

OBJECTIVES

The aim was to evaluate the safety and efficacy of different immunosuppressive treatments for adult patients with PMN and nephrotic syndrome.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 1 April 2021 with support from the Cochrane Kidney and Transplant Information Specialist using search terms relevant to this review. Studies in the Register were identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) investigating effects of immunosuppression in adults with PMN and nephrotic syndrome were included.

DATA COLLECTION AND ANALYSIS

Study selection, data extraction, quality assessment, and data synthesis were performed using Cochrane-recommended methods. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes, and mean difference (MD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

Sixty-five studies (3807 patients) were included. Most studies exhibited a high risk of bias for the domains, blinding of study personnel, participants and outcome assessors, and most studies were judged unclear for randomisation sequence generation and allocation concealment. Immunosuppressive treatment versus placebo/no treatment/non-immunosuppressive treatment In moderate certainty evidence, immunosuppressive treatment probably makes little or no difference to death, probably reduces the overall risk of ESKD (16 studies, 944 participants: RR 0.59, 95% CI 0.35 to 0.99; I² = 22%), probably increases total remission (complete and partial) (6 studies, 879 participants: RR 1.44, 95% CI 1.05 to 1.97; I² = 73%) and complete remission (16 studies, 879 participants: RR 1.70, 95% CI 1.05 to 2.75; I² = 43%), and probably decreases the number with doubling of serum creatinine (SCr) (9 studies, 447 participants: RR 0.46, 95% CI 0.26 to 0.80; I² = 21%). However, immunosuppressive treatment may increase the number of patients relapsing after complete or partial remission (3 studies, 148 participants): RR 1.73, 95% CI 1.05 to 2.86; I² = 0%) and may lead to a greater number experiencing temporary or permanent discontinuation/hospitalisation due to adverse events (18 studies, 927 participants: RR 5.33, 95% CI 2.19 to 12.98; I² = 0%). Immunosuppressive treatment has uncertain effects on infection and malignancy. Oral alkylating agents with or without steroids versus placebo/no treatment/steroids Oral alkylating agents with or without steroids had uncertain effects on death but may reduce the overall risk of ESKD (9 studies, 537 participants: RR 0.42, 95% CI 0.24 to 0.74; I² = 0%; low certainty evidence). Total (9 studies, 468 participants: RR 1.37, 95% CI 1.04 to 1.82; I² = 70%) and complete remission (8 studies, 432 participants: RR 2.12, 95% CI 1.33 to 3.38; I² = 37%) may increase, but had uncertain effects on the number of patients relapsing, and decreasing the number with doubling of SCr. Alkylating agents may be associated with a higher rate of adverse events leading to discontinuation or hospitalisation (8 studies 439 participants: RR 6.82, 95% CI 2.24 to 20.71; I² = 0%). Oral alkylating agents with or without steroids had uncertain effects on infection and malignancy. Calcineurin inhibitors (CNI) with or without steroids versus placebo/no treatment/supportive therapy/steroids We are uncertain whether CNI with or without steroids increased or decreased the risk of death or ESKD, increased or decreased total or complete remission, or reduced relapse after complete or partial remission (low to very low certainty evidence). CNI also had uncertain effects on decreasing the number with a doubling of SCr, temporary or permanent discontinuation or hospitalisation due to adverse events, infection, or malignancy. Calcineurin inhibitors (CNI) with or without steroids versus alkylating agents with or without steroids We are uncertain whether CNI with or without steroids increases or decreases the risk of death or ESKD. CNI with or without steroids may make little or no difference to total remission (10 studies, 538 participants: RR 1.01, 95% CI 0.89 to 1.15; I² = 53%; moderate certainty evidence) or complete remission (10 studies, 538 participants: RR 1.15, 95% CI 0.84 to 1.56; I² = 56%; low certainty evidence). CNI with or without steroids may increase relapse after complete or partial remission. CNI with or without steroids had uncertain effects on SCr increase, adverse events, infection, and malignancy. Other immunosuppressive treatments Other interventions included azathioprine, mizoribine, adrenocorticotropic hormone, traditional Chinese medicines, and monoclonal antibodies such as rituximab. There were insufficient data to draw conclusions on these treatments.

AUTHORS' CONCLUSIONS

This updated review strengthened the evidence that immunosuppressive therapy is probably superior to non-immunosuppressive therapy in inducing remission and reducing the number of patients that progress to ESKD. However, these benefits need to be balanced against the side effects of immunosuppressive drugs. The number of included studies with high-quality design was relatively small and most studies did not have adequate follow-up. Clinicians should inform their patients of the lack of high-quality evidence. An alkylating agent (cyclophosphamide or chlorambucil) combined with a corticosteroid regimen had short- and long-term benefits, but this was associated with a higher rate of adverse events. CNI (tacrolimus and cyclosporin) showed equivalency with alkylating agents however, the certainty of this evidence remains low. Novel immunosuppressive treatments with the biologic rituximab or use of adrenocorticotropic hormone require further investigation and validation in large and high-quality RCTs.

Rituximab Therapy for Primary Membranous Nephropathy in a Chinese Cohort

Background: Rituximab has become one of the first-line therapies for the treatment of moderate and high-risk primary membranous nephropathy (pMN). We retrospectively reviewed 95 patients with pMN who received rituximab therapy and focused on the therapeutic effects and safety of this therapy in a Chinese cohort.

Methods: Ninety-five consecutive patients with pMN diagnosed by kidney biopsy received rituximab and were followed up for >6 months. Four weekly doses of rituximab (375 mg/m²) was adopted as the initial administration. Repeated single infusions were administrated to maintain B cell depletion levels of <5 cells/mL.

Results: A total of 91 patients completed rituximab therapy with the total dose of 2.4 (2.0, 3.0) g; 64/78 (82.1%) patients achieved anti-PLA2R antibody depletion in 6.0 (1.0, 12.0) months; 53/91 (58.2%) patients achieved clinical remission in 12.0 (6.0, 24.0) months, including complete remission in 18.7% of patients and partial remission in 39.6% of patients. Multivariate logistic regression analysis showed that severe proteinuria (OR = 1.22, P = 0.006) and the persistent positivity of anti-PLA2R antibodies (OR = 9.00, P = 0.002) were independent risk factors for no-remission. The remission rate of rituximab as an initial therapy was higher than rituximab as an alternative therapy (73.1 vs. 52.3%, P = 0.038). Lastly, 45 adverse events occurred in 37 patients, but only one patient withdrew from treatment due to severe pulmonary infection.

Conclusion: Rituximab is a safe and effective treatment option for Chinese patients with pMN, especially as an initial therapy.

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."

Clinical Response and Pattern of B cell Suppression with Single Low Dose Rituximab in Nephrology

Background

There is no consensus regarding dose and frequency of rituximab in nephrology with extrapolation of doses used in treating lymphoproliferative disorders. There are no guidelines on targeting initial and subsequent doses on the basis of CD19⁺ B cells.

Methods

Initially, 100 mg rituximab was given to 42 adults with steroid-dependent nephrotic syndrome (SDNS) and frequently relapsing nephrotic syndrome (FRNS), idiopathic membranous nephropathy (MN), and high-immunologic-risk kidney transplantation. Absolute and percentage levels of CD19 B cells and clinical status were assessed at baseline, days 30, 90, and 180, and at 1 year. Subsequent doses of rituximab were on the basis of CD19 B cell reconstitution and clinical response.

Results

CD19 B cell percentage decreased from 16.3 ± 7.6 to 0.3 ± 0.3 (P≤0.001), 1.9 ± 1.7 (P≤0.001), and 4.0 ± 4.5 (P=0.005) by 30, 90, and 180 days, respectively. Suppression of CD19 B cell count below 1% at days 30, 90, and 180 was seen in 40 of 42 (95.2%), 18 of 42 (42.9%), and 7 of 42 (16.7%) patients, respectively. Of 30 with SDNS and FRNS followed up for 1 year, 29 (96.7%) went into remission at day 30. Remission was sustained in 23 (76.6%) at day 180 and 21 (70%) at 1 year. There was a significant decrease (P<0.001) in the dose of steroids needed to maintain remission at 180 days after rituximab (0.27 ± 0.02 mg/kg to 0.02 ± 0.00 mg/kg). CD19 B cell percentage at 90 days correlated with relapse (P=0.001; odds ratio 1.42; 95% confidence interval, 1.25 to 2.57). Eighteen (60%) required an additional dose. Of five with MN, four achieved remission by 6 months, which was sustained in three by 1 year. Of the seven kidney transplant recipients, two had antibody-mediated rejections, although CD19 B cells were suppressed even at 1 year.

Conclusions

Low-dose rituximab induces sustained depletion of CD19 B cells for up to 90 days. Its role in preventing relapses in SDNS, FRNS, MN, and rejection needs further study.

Rituximab in Patients With Phospholipase A2 Receptor-Associated Membranous Nephropathy and Severe CKD

Introduction

Patients with phospholipase A2 receptor (PLA2R)–associated membranous nephropathy and stage 4 or 5 chronic kidney disease are at high risk of end-stage kidney disease. In recent years, rituximab (RTX) emerged as a safe and efficient treatment for patients with PLA2R-associated membranous nephropathy. Whether its use is also appropriate in patients with an estimated glomerular filtration rate <30 ml/min per 1.73 m² has not been investigated.

Methods

We retrospectively reviewed characteristics and outcome of 13 patients with PLA2R-associated membranous nephropathy and stage 4 or 5 chronic kidney disease who received a total of 14 consecutive RTX treatments from January 2012 to March 2018. The treatment regimen consisted of either 2 weekly infusions of 375 mg/m² or 2 RTX infusions of 1 g/d two weeks apart. When needed, the regimen was repeated to achieve immunological remission.

Results

The mean estimated glomerular filtration rate, serum albumin level, and urinary protein level at the first RTX infusion were 18 ± 7 ml/min per 1.73 m², 25.2 ± 5.4 g/l, and 13.2 ± 7.5 g/d, respectively, with all patients being tested positive for serum PLA2R antibodies. Ten treatment courses led to an increase in estimated glomerular filtration rate and remission of nephrotic syndrome after a median follow-up of 40.8 months (interquartile range, 14.8–46.8). Conversely, 4 RTX treatments were unsuccessful, with patients requiring chronic hemodialysis within 1 year. The urinary albumin-to-protein ratio before treatment was predictive of renal response. Immunological remission occurred after 11 treatment courses and was associated with clinical response in 10 of 11 patients. Three patients experienced severe adverse events.

Conclusion

RTX seems effective and reasonably safe in PLA2R-associated membranous nephropathy with stage 4 or 5 chronic kidney disease. Immunological remission is associated with a good clinical outcome.

Membranous Nephropathy Posttransplantation: An Update of the Pathophysiology and Management

Membranous nephropathy (MN) is a common cause of nephrotic syndrome after transplantation and is associated with an increased risk of allograft loss. MN may occur either as a recurrent or as a de novo disease. As in native kidneys, the pathophysiology of the MN recurrence is in most cases associated with antiphospholipid A2 receptor antibodies. However, the posttransplant course has some distinct features when compared with primary MN, including a lower chance of spontaneous remission and a greater requirement for adjuvant immunosuppressive therapy to induce complete remission. Although the efficacy of rituximab in primary MN is now well established, no randomized studies have assessed its effectiveness in MN after transplant, and there are no specific recommendations for the management of these patients. This review aims to synthesize and update the pathophysiology of posttransplant MN, as well as to address unsolved issues specific to transplantation, including the prognostic value of antiphospholipid A2 receptor, the risk of living-related donation, the link between de novo MN and rejection, and different therapeutic strategies so far deployed in posttransplant MN. Lastly, we propose a management algorithm for patients with MN who are planning to receive a kidney transplant, including pretransplant considerations, posttransplant monitoring, and the clinical approach after the diagnosis of recurrence.

Membranous Nephropathy (MN) Recurrence After Renal Transplantation

Primary membranous nephropathy (MN) is a frequent cause of NS in adults. In native kidneys the disease may progress to ESRD in the long term, in some 40–50% of untreated patients. The identification of the pathogenic role of anti-podocyte autoantibodies and the development of new therapeutic options has achieved an amelioration in the prognosis of this disease. MN may also develop in renal allograft as a recurrent or a de novo disease. Since the de novo MN may have some different pathogenetic and morphologic features compared to recurrent MN, in the present paper we will deal only with the recurrent disease. The true incidence of the recurrent form is difficult to assess. This is mainly due to the variable graft biopsy policies in kidney transplantation, among the different transplant centers. Anti-phospholipase A2 receptor (PLA2R) autoantibodies are detected in 70–80% of patients. The knowledge of anti-PLA2R status before transplant is useful in predicting the risk of recurrence. In addition, the serial survey of the anti-PLA2R titers is important to assess the rate of disease progression and the response to treatment. Currently, there are no established guidelines for prevention and treatment of recurrent MN. Symptomatic therapy may help to reduce the signs and symptoms related to the nephrotic syndrome. Anecdotal cases of response to cyclical therapy with steroids and cyclophosphamide have been published. Promising results have been reported with rituximab in both prophylaxis and treatment of recurrence. However, these results are based on observational data, and prospective controlled trials are still missing.

A case report of remission of refractory membranous nephropathy progressing to stage 4 chronic kidney disease using low-dose rituximab: A long-term follow-up

RATIONALE

As suggested by the 2012 KDIGO guidelines, persistent elevation of serum creatinine > 3.5 mg/dl (> 309 μmol/l) (or an estimated glomerular filtration rate < 30 ml/min per 1.73 m is one of contradictions for the use of immunosuppressive therapy in membranous nephropathy.

PATIENT CONCERNS

A 45-year-old man with membranous nephropathy negative for serum anti-phospholipase-A2-receptor antibody, showed no response to corticosteroids and cyclophosphamide. He progressed to chronic kidney disease stage 4 (CKD4) under tacrolimus and relapsed after withdrawal.

DIAGNOSES

The patient received repeated renal biopsy, comfirming the diagnosis of membranous nephropathy with progressive glomerular and tubulointerstitial scarring.

INTERVENTIONS

He was treated with successfully four times with lose-dose (180 mg/m every 2-3 months) rituximab (RTX) depending on his B cell counts, aiming to remain at 0-5 cells/μl.

OUTCOMES

The patient was followed-up for almost 6 years. He achieved a partial remission at 11 months and a complete remission of the nephritic range of proteinuria at 34 months following infusion of RTX. RTX was well tolerated and the patient's renal function improved. He had no edema and his dosage of corticosteroids could be discontinued.

LESSONS

This case strongly suggested that rituximab has promising therapeutic significance, even in patients progressing to CKD4.

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

Background

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

Methods

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

Results

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

Conclusion

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

Single-dose Rituximab Therapy for Refractory Idiopathic Membranous Nephropathy: A Single-center Experience

To date, a recognized treatment for refractory membranous nephropathy (MN) has not been established. Recently, several reports have indicated the efficacy of rituximab as a novel treatment option. However, only a few published accounts exist of rituximab therapy for idiopathic MN (IMN) in the Asian population. We present the cases of three IMN patients who were treated with single-dose rituximab after they showed no response to conventional therapies, including corticosteroids, cyclosporine, cyclophosphamide, mizoribine, and mycophenolate mofetil. Although one case showed no response, a complete or incomplete remission was achieved in the other two cases. Rituximab may therefore be a beneficial treatment option for IMN.

Rituximab in Membranous Nephropathy: Not All Studies Are Created Equal

Many prospective studies and a recent randomized controlled trial have shown that the B-cell-depleting monoclonal antibody, rituximab, safely promotes the remission of nephrotic syndrome in approximately 65% of patients with membranous nephropathy (MN). Mechanistic studies have indicated that rituximab-induced proteinuria reduction is associated with clearance of anti-podocyte antigens phospholipase 2 receptor autoantibodies and subepithelial immune complexes, the hallmarks of the disease. A recently published study reported results which, at first sight, looked less favorable and implied that, due to a publication bias against negative results, the efficacy of rituximab in MN might be overestimated. Since patients received only one or 2 rituximab administrations, the authors suggest that when rituximab is used, higher doses and longer treatments should be considered. In this study, we highlight limitations of the study and warn against an oversimplified interpretation of the data. Though information on the optimal dose of rituximab to use in MN is still limited, available data from studies with predefined rituximab administration protocols collectively support the concept of titrating rituximab to the number of circulating B-cells that are invariably depleted after the first or second administration. Additional doses may increase the risk of adverse effects and related costs without augmenting efficacy. Importantly, underpowered studies with inconclusive results should not be confused with negative studies formally proving a neutral effect of a treatment. Until data from ad hoc designed clinical trials are available, the B-cell-driven protocol should be the preferred regimen, since it is similarly effective, but safer and more cost effective than other protocols employing multiple rituximab administrations.

Biologics for the treatment of autoimmune renal diseases

Biological therapeutics (biologics) that target autoimmune responses and inflammatory injury pathways have a marked beneficial impact on the management of many chronic diseases, including rheumatoid arthritis, psoriasis, inflammatory bowel disease, and ankylosing spondylitis. Accumulating data suggest that a growing number of renal diseases result from autoimmune injury - including lupus nephritis, IgA nephropathy, anti-neutrophil cytoplasmic antibody-associated glomerulonephritis, autoimmune (formerly idiopathic) membranous nephropathy, anti-glomerular basement membrane glomerulonephritis, and C3 nephropathy - and one can speculate that biologics might also be applicable to these diseases. As many autoimmune renal diseases are relatively uncommon, with long natural histories and diverse outcomes, clinical trials that aim to validate potentially useful biologics are difficult to design and/or perform. Some excellent consortia are undertaking cohort studies and clinical trials, but more multicentre international collaborations are needed to advance the introduction of new biologics to patients with autoimmune renal disorders. This Review discusses the key molecules that direct injurious inflammation and the biologics that are available to modulate them. The opportunities and challenges for the introduction of relevant biologics into treatment protocols for autoimmune renal diseases are also discussed.

Recurrent Membranous Nephropathy After Kidney Transplantation: Treatment and Long-Term Implications

BACKGROUND

Membranous nephropathy (MN) can recur in kidney allografts leading to graft dysfunction and failure. The aims of these analyses were to assess MN recurrence, clinical and histologic progression, and response to anti-CD20 therapy.

METHODS

Included were 63 kidney allograft recipients with biopsy proven primary MN followed up for 77.0 (39-113) months (median, interquartile range). Disease recurrence was diagnosed by biopsy (protocol or clinical), and follow-up was monitored by laboratory parameters and protocol biopsies.

RESULTS

Thirty of 63 patients (48%) had histologic recurrence often during the first year. In 53% of the cases, recurrence was diagnosed by protocol biopsy. Recurrence risk was higher in patients with higher proteinuria pretransplant [hazard ratio = 1.869 (95% confidence interval, 1.164-3.001) per gram, P = 0.010] and those with anti-phospholipase A2 receptor antibodies [hazard ratio = 3.761 (1.635-8.652), P = 0.002]. Thirteen patients with recurrence had no clinical progression, and in 2, MN resolved histologically. Seventeen of 63 patients (27%) had progressive proteinuria and were treated with anti-CD20 antibodies, resulting in complete response in 9 (53%), partial response in 5 (29%), and no response in 3 (18%). Posttreatment biopsies were obtained in 15 patients and showed histologic resolution in 6 (40%). Disease recurrence did not correlate with graft survival. However, 5 of 11 (45.4%) graft losses were due to recurrent MN. Death-censored graft survival in MN did not differ from that of 273 control recipients with autosomal dominant polycystic kidney disease.

CONCLUSIONS

Membranous nephropathy recurs in 48% of cases threatening the allograft. Treatment of early but progressive recurrence with anti-CD20 antibodies is quite effective achieving clinical remission and histologic resolution of MN.

A new rescue regimen with plasma exchange and rituximab in high-risk membranous glomerulonephritis

BACKGROUND

Even though current treatment guidelines for idiopathic membranous glomerulonephritis (iMGN) exist, many questions regarding an optimal therapy remain unanswered. Complete remission cannot be achieved in all patients; relapses occur, in some cases frequently, and side effects from the immunosuppressive therapy are common. Therapeutic options in high-risk patients not responding to standard immunosuppressive therapies are limited. Recent research reveals that the human M-type phospholipase A2 receptor (PLA2 R) is a causative factor in iMGN that parallels clinical disease activity. However, in some patients, this correlation is not evident and additional undetermined factors seem to play a role.

DESIGN

We evaluated a new rescue protocol including plasma exchanges (PE) against albumin, intravenous immunoglobulins (IVIGs) and rituximab for 10 patients with a biopsy-proven diagnosis of iMGN who were therapy-resistant to all conventional regimens and had a urinary protein to creatinine ratio of more than 10 000 mg/g Crea. We compared this protocol with standard immunosuppressive protocols including monthly alternating prednisolone plus cyclophosphamide (18 patients), cyclosporine plus prednisolone (23 patients) and rituximab alone (eight patients) in a retrospective design.

RESULTS

Our rescue regimen with PE, IVIGs and rituximab achieved partial remission in 90% of patients who had been otherwise refractory to therapy. The mean time to partial remission was 2·1 months. Furthermore, two anti-PLA2 R-antibody negative patients were also treated with this rescue regimen, achieving partial remission after 1 and 4 months.

CONCLUSION

A combination of PE, IVIGs and rituximab is a treatment option to consider for high-risk patients with iMGN who are refractory to conventional therapy.

B cell suppression in primary glomerular disease

Membranous nephropathy, focal segmental glomerulosclerosis (FSGS), and minimal change disease (MCD) are the most common causes of idiopathic nephrotic syndrome. For many years prednisone, alkylating agents, and calcineurin inhibitors have been the standard of therapy for these patients. More effective or better tolerated treatment modalities are needed. B cell targeted therapy was recently introduced in clinical practice. In this review, we briefly summarize the current standard therapy and discuss the efficacy of B cell targeted therapy in primary glomerular diseases. Observational, short-term studies suggest that rituximab is effective and comparable to standard therapy in maintaining remissions in patients with frequently relapsing or steroid-dependent MCD or FSGS. In contrast, response is limited in patients with steroid-resistant nephrotic syndrome. Rituximab also induces remissions in patients with membranous nephropathy. Controlled clinical trials on kidney endpoints are urgently needed to position B cell targeted therapy in clinical practice.

Treatment of idiopathic membranous nephropathy

Immunosuppressive treatment of patients with idiopathic membranous nephropathy (iMN) is heavily debated. The controversy is mainly related to the toxicity of the therapy and the variable natural course of the disease-spontaneous remission occurs in 40-50% of patients. The 2012 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline for Glomerulonephritis provides guidance for the treatment of iMN. The guideline suggests that immunosuppressive therapy should be restricted to patients with nephrotic syndrome and persistent proteinuria, deteriorating renal function or severe symptoms. Alkylating agents are the preferred therapy because of their proven efficacy in preventing end-stage renal disease. Calcineurin inhibitors can be used as an alternative although efficacy data on hard renal end points are limited. In this Review, we summarize the KDIGO guideline and address remaining areas of uncertainty. Better risk prediction is needed to identify patients who will benefit from immunosuppressive therapy, and the optimal timing and duration of this therapy is unknown because most of the randomized controlled trials were performed in low-risk or medium-risk patients. Alternative therapies, directed at B cells, are under study. The discovery of anti-M type phospholipase A2 receptor-antibodies is a major breakthrough and we envisage that in the near future, antibody-driven therapy will enable more individualized treatment of patients with iMN.

Rituximab therapy in nephrotic syndrome: implications for patients' management

Rituximab offers an alternative to current immunosuppressive therapies for difficult-to-treat nephrotic syndrome. The best outcomes are seen in patients with steroid-dependent nephrotic syndrome who have failed to respond to multiple therapies. By contrast, the benefits of rituximab therapy are limited in patients with steroid-resistant nephrotic syndrome, particularly those with focal segmental glomerulosclerosis (FSGS). Therapy with plasma exchange and one or two doses of rituximab has shown success in patients with recurrent FSGS. Young patients and those with normal serum albumin at recurrence of nephrotic syndrome are most likely to respond to rituximab therapy. A substantial proportion of rituximab-treated patients with idiopathic membranous nephropathy show complete or partial remission of proteinuria, and reduced levels of phospholipase A(2) receptor autoantibodies, which are implicated in the pathogenesis of this disorder. Successful rituximab therapy induces prolonged remission and enables discontinuation of other medications without substantially increasing the risk of infections and other serious adverse events. However, the available evidence of efficacy of rituximab therapy is derived chiefly from small case series and requires confirmation in prospective, randomized, controlled studies that define the indications for use and predictors of response to this therapy.

Depletion of B lymphocytes in idiopathic membranous glomerulopathy: results from patients with extended follow-up

Aims

To assess the long-term therapeutic benefit of temporary depletion of B lymphocytes in patients with idiopathic membranous glomerulopathy (MGN) and search for potential predictors of response.

Patients and Methods

The patients included had been diagnosed with biopsy-proven MGN in the absence of secondary causes. Estimated glomerular filtration rate should be above 30 ml/min/1.73 m² and 24-hour proteinuria 3 g/day or more. Patients who had been treated with cyclosporine or cytotoxic agents the year prior to study entry were excluded. Depletion of B cells was achieved with rituximab, which was administered intravenously for 4 consecutive weeks. Partial remission was defined as a >50% decrease in proteinuria with absolute proteinuria <3 g/day, while complete remission was defined as a >50% decrease in proteinuria and an absolute protein excretion <0.3 g/day.

Results

Twelve patients were studied (4 females/8 males) with a mean age of 51.3 years. No major adverse effects were observed. During a median follow-up time of 48 months, 11/12 (91.6%) patients achieved remission [7/12 (58.3%) complete remission and 4/12 (33.3%) partial remission], while 1 patient did not respond to therapy. Twelve months after therapy, 68.8% (p = 0.003) of cases had achieved partial and 28.4% complete remission. Measurements of lymphocyte subpopulations did not reveal any changes except for the B cell depletion. B cell infiltrates captured per mm³ of renal tissue in the diagnostic biopsy did not correlate with subsequent response.

Conclusion

Depletion of B cells in idiopathic MGN was well tolerated and resulted in significant and long-lasting response rates in a series of 12 patients.

A case of membranous nephropathy as a manifestation of graft-versus-host disease

Nephrotic syndrome (NS) rarely occurs after hematopoietic stem cell transplantation (HSCT) as a late manifestation of graft-versus-host disease (GVHD). Herein, we report a case of HSCT-associated membranous nephropathy in a female patient with aplastic anemia. The patient received an allogeneic HSCT from her human leukocyte antigen-identical brother following myeloablative conditioning chemotherapy. NS occurred 21 months after HSCT without any concurrent features of chronic GVHD. The patient was treated with prednisolone and cyclosporine after renal biopsy confirmed membranous nephropathy, and achieved complete remission. Our report contradicts previous assumptions that concomitant chronic GVHD is responsible for the development of NS, suggesting that NS can develop as a new, independent manifestation of GVHD.

Low- and high-molecular-weight urinary proteins as predictors of response to rituximab in patients with membranous nephropathy: a prospective study

BACKGROUND

Selective urinary biomarkers have been considered superior to total proteinuria in predicting response to treatment and outcome in patients with membranous nephropathy (MN).

METHODS

We prospectively tested whether urinary (U) excretion of retinol-binding protein (RBP), α1-microglobulin (α1M), albumin, immunoglobulin IgG and IgM and/or anti-phospholipase 2 receptor (PLA(2)R) levels could predict response to rituximab (RTX) therapy better than standard measures in MN. We also correlated changes in antibodies to PLA(2)R with these urinary biomarkers.

RESULTS

Twenty patients with MN and proteinuria (P) >5 g/24 h received RTX (375 mg/m(2) × 4) and at 12 months, 1 patient was in complete remission (CR), 9 were in partial remission (PR), 5 had a limited response (LR) and 4 were non-responders (NR). At 24 months, CR occurred in 4, PR in 12, LR in 1, NR in 2 and 1 patient relapsed. By simple linear regression analysis, UIgG at baseline (mg/24 h) was a significant predictor of change in proteinuria at 12 months (Δ urinary protein) (P = 0.04). In addition, fractional excretion (FE) of IgG, urinary alpha 1 microglobulin (Uα1M) (mg/24 h) and URBP (μg/24 h) were also predictors of response (P = 0.05, 0.04, and 0.03, respectively). On the other hand, UIgM, FEIgM, albumin and FE albumin did not predict response (P = 0.10, 0.27, 0.22 and 0.20, respectively). However, when results were analyzed in relation to proteinuria at 24 months, none of the U markers that predicted response at 12 m could predict response at 24 m (P = 0.55, 0.42, 0.29 and 0.20). Decline in anti-PLA(2)R levels was associated with and often preceded urinary biomarker response but positivity at baseline was not a predictor of proteinuria response.

CONCLUSIONS

The results suggest that in patients with MN, quantification of low-, medium- and high-molecular-weight urinary proteins may be associated with rate of response to RTX, but do not correlate with longer term outcomes.

Partial therapeutic response to Rituximab for the treatment of chronic alloantibody mediated rejection of kidney allografts

BACKGROUND AND OBJECTIVES

Chronic rejection leads to kidney allograft failure and develops in many kidney transplant recipients. One cause of chronic rejection, chronic antibody mediated rejection (CAMR), is attributed to alloantibodies. Maintenance immunosuppression including prednisone, mycophenolate mofetil (MMF) and calcineurin inhibitors may limit alloantibody production in some patients, but many maintain or develop alloantibody production, leading to CAMR. Therefore, no efficacious therapy to treat CAMR is presently available to prevent the progression of CAMR to kidney allograft failure.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

We performed a retrospective review of 31 subjects with CAMR, of which 14 received Rituximab and 17 subjects did not. Response to Rituximab was defined as decline or stabilization of serum creatinine for at least one year. Data reviewed included demographic, clinical, allograft, post-transplant, and pathological variables. Pathological variables in the diagnostic allograft biopsy were scored according to Banff criteria.

RESULTS

The median survival time (MST) for allografts in the control group was 439 days, and for the Rituximab treated group was 685 days. The Rituximab group was dichotomous with 8 subjects showing a medial survival time of 1180 days, and 6 subjects having a median survival time of 431 days. The MST for the responders was statistically significant from the non-responders and controls. No pathological parameter distinguished any subset of subjects.

CONCLUSIONS

These data show that Rituximab followed by standard maintenance immunosuppression shows a therapeutic effect in the treatment of CAMR, which is confined to a subset of treated subjects, not identifiable a priori.

Treatment of idiopathic membranous nephropathy

Exciting progress recently has been made in our understanding of idiopathic membranous nephropathy, as well as treatment of this disease. Here, we review important advances regarding the pathogenesis of membranous nephropathy. We will also review the current approach to treatment and its limitations and will highlight new therapies that are currently being explored for this disease including Rituximab, mycophenolate mofetil, and adrenocorticotropic hormone, with an emphasis on results of the most recent clinical trials.

Our experience with rituximab therapy for adult-onset primary glomerulonephritis and review of literature

BACKGROUND

B cell-targeted immunosuppression with rituximab as primary treatment or when conventional therapy is contraindicated or unsuccessful can induce remission in idiopathic membranous nephropathy (IMN). We explored the efficacy and safety of rituximab therapy in an adult population with IMN and other primary glomerulonephritides.

METHOD

This study is a single-centre retrospective case review of 24 adult patients who received rituximab (RTX) for IMN (n = 11), minimal change disease (MCD, n = 7), focal segmental glomerulosclerosis (FSGS, n = 4), and membranoproliferative glomerulonephritis (MPGN, n = 2). Outcomes included the proportion of patients with complete and partial remission, frequency of relapse, the amount of post-RTX immunosuppression, and toxicity.

RESULTS

The median follow-up for all patients was 31.5 months (IQR: 15.0-44.0). Rituximab therapy induced remission in 19/24 (79.2 %) patients (IMN: 63.6 %, MCD: 100 %, FSGS: 75 %, and MPGN: 100 %). Disease recurrence in patients with ≥ 3 relapses pre-RTX therapy (MCD, n = 6 and FSGS, n = 1) decreased from 37.0 to 19.6 events per 1,000 patient-months. All patients with steroid maintenance, discontinued or achieved at least a 50 % dose reduction at 3.0 months (IQR: 1.5-8.0) post-treatment. One patient ceased CSA in addition to a 50 % steroid dose reduction 13 months post-RTX. Rituximab was well tolerated with a single serious infection (4.2 %) responsive to treatment.

CONCLUSIONS

Rituximab induced remission in IMN comparable with published reports but had an additional benefit in inducing remission in other common glomerulonephritides. Additional randomized studies are needed to confirm its potential therapeutic benefit and optimal dosing for adult-onset primary glomerulonephritis.

Rituximab in children with resistant idiopathic nephrotic syndrome

Idiopathic nephrotic syndrome resistant to standard treatments remains a therapeutic dilemma in pediatric nephrology. To test whether the anti-CD20 monoclonal antibody rituximab may benefit these patients, we conducted an open-label, randomized, controlled trial in 31 children with idiopathic nephrotic syndrome unresponsive to the combination of calcineurin inhibitors and prednisone. All children continued prednisone and calcineurin inhibitors at the doses prescribed before enrollment, and one treatment group received two doses of rituximab (375 mg/m(2) intravenously) as add-on therapy. The mean age was 8 years (range, 2-16 years). Rituximab did not reduce proteinuria at 3 months (change, -12% [95% confidence interval, -73% to 110%]; P=0.77 in analysis of covariance model adjusted for baseline proteinuria). Additional adjustment for previous remission and interaction terms (treatment by baseline proteinuria and treatment by previous remission) did not change the results. In conclusion, these data do not support the addition of rituximab to prednisone and calcineurin inhibitors in children with resistant idiopathic nephrotic syndrome.

Chronic alloantibody mediated rejection

Alloantibodies clearly cause acute antibody mediated rejection, and all available evidence supports their pathogenic etiology in the development of chronic alloantibody mediated rejection (CAMR). But the slow evolution of this disease, the on-going immunosuppression, the variations in titer of alloantibodies, and variation in antigenic targets all complicate identifying which dynamic factors are most important clinically and pathologically. This review highlights the pathological factors related to the diagnosis of CAMR, the time course and natural history of this disease. What is known about CAMR pathogenesis is discussed including alloantibodies, the role of complement, gene activation, and Fc effector cell function. Therapy, which is problematic for this disease, is also discussed, including on-going and potential therapies and their limitations.

Rituximab in immunologic glomerular diseases

Experimental data suggest that the B-cell antigen CD20 may play a significant role in the pathogenesis of many diseases including glomerular diseases. These and other findings underpin the central concept of B-cell-depleting therapies that target CD20 antigen as treatments for lupus nephritis, idiopathic membranous nephropathy, focal segmental glomerulosclerosis, cryglobulinemic glomerulonephritis, antibody mediated renal allograft rejection and recurrent glomerulonephritis in renal allograft. Use of rituximab as a B-cell depleting therapy has been associated with clinical improvement and has emerged as a possible adjunct or alternative treatment option in this field of nephrology.

Management of hepatitis C in patients with chronic kidney disease

Chronic kidney disease represents a global health problem. Chronic hepatitis C virus (HCV) infection is prevalent in patients with end stage renal disease (ESRD) on hemodialysis (HD) and in renal transplant recipients with significant impact on morbidity and mortality. Furthermore, HCV can cause various forms of glomerulopathy with the predominant type being cryglobulinemia associated membranoproliferative glomerulonephritis. Liver enzymes are traditionally used as markers of liver injury; however, there is wide variation in aminotransferase levels in patients with ESRD. Therefore, diagnosis of chronic hepatitis C (CHC) in patients with ESRD is based on HCV antibody testing and further confirmation with polymerase chain reaction testing. Current standard therapy for CHC is composed of pegylated interferon and ribavirin. However, this combination is challenging in patients with ESRD due to its tolerability. We describe in this review relevant issues in epidemiology, diagnosis and management of CHC in ESRD, HD and renal transplant recipients.

Rituximab treatment for membranous nephropathy: a French clinical and serological retrospective study of 28 patients

The development of well-tolerated and effective therapies that target the pathogenesis of membranous nephropathy (MN) would be useful. Our objective was to evaluate the efficacy of rituximab in MN. We analyzed the outcome of 28 patients treated with rituximab for idiopathic MN. Anti-PLA₂R antibodies in serum and PLA₂R antigen in kidney biopsy were assessed in 10 and 9 patients, respectively. Proteinuria was significantly decreased by 56, 62 and 87% at 3, 6 and 12 months, respectively. At 6 months, 2 patients achieved complete remission (CR) and 12 partial remission (PR; overall renal response, 50%). At 12 months (n = 23), CR was achieved in 6 patients and PR in 13 patients (overall renal response, 82.6%). Three patients suffered a relapse of nephrotic proteinuria 27–50 months after treatment. Univariate analysis suggested that the degree of renal failure (MDRD estimated glomerular filtration rate <45/ml/min/1.73 m²) is an independent factor that predicts lack of response to rituximab. Anti-PLA₂R antibodies were detected in the serum of 10 patients, and PLA₂R antigen in immune deposits in 8 of 9 patients. Antibodies became negative in all 5 responsive patients with available follow-up sera. In this retrospective study, a high rate of remission was achieved 12 months after treatment.

Short-term effects of rituximab in children with steroid- and calcineurin-dependent nephrotic syndrome: a randomized controlled trial

BACKGROUND AND OBJECTIVES

Prednisone and calcineurin inhibitors are the mainstay therapy of idiopathic nephrotic syndrome (INS) in children. However, drug dependence and toxicity associated with protracted use are common. Case series suggest that the anti-CD20 monoclonal antibody rituximab (RTX) may maintain disease remission.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This open-label randomized controlled trial was powered to show that a strategy based on RTX and lower doses of prednisone and calcineurin inhibitors was noninferior to standard doses of these agents in maintaining 3-month proteinuria as low as baseline or up to 1 g/d greater (noninferiority margin). Participants were stratified by the presence of toxicity to prednisone/calcineurin inhibitors and centrally assigned to add RTX (Mabthera, 375 mg/m(2) intravenously) to lower doses of standard agents or to continue with current therapy alone. The risk of relapse was a secondary outcome.

RESULTS

Fifty-four children (mean age 11 ± 4 years) with INS dependent on prednisone and calcineurin inhibitors for >12 months were randomized. Three-month proteinuria was 70% lower in the RTX arm (95% confidence interval 35% to 86%) as compared with standard therapy arm (intention-to-treat); relapse rates were 18.5% (intervention) and 48.1% (standard arm) (P = 0.029). Probabilities of being drug-free at 3 months were 62.9% and 3.7%, respectively (P < 0.001); 50% of RTX cases were in stable remission without drugs after 9 months.

CONCLUSIONS

Rituximab and lower doses of prednisone and calcineurin inhibitors are noninferior to standard therapy in maintaining short-term remission in children with INS dependent on both drugs and allow their temporary withdrawal.

Correlation between B Lymphocyte Abnormality and Disease Activity in Patients with Idiopathic Membranous Nephropathy

This study investigated the relationship between peripheral blood B lymphocytes, regulatory T-cells and T lymphocyte subsets, the distribution of B lymphocytes in the kidney, and the pathogenesis of idiopathic membranous nephropathy (IMN). Lymphocyte subsets were measured using flow cytometry in 66 patients with clinically-confirmed IMN and in 40 healthy control subjects. Compared with healthy subjects, the number of peripheral blood B lymphocytes was significantly increased in IMN patients and that of regulatory T-cells was significantly decreased, accompanied by an increased CD4+/CD8+ T-cell ratio. There was no relationship between the number of peripheral blood B lymphocytes and markers of kidney function. Although the number of infiltrating B lymphocytes in the kidney of IMN patients was higher, there was no relationship with the number of peripheral blood B lymphocytes. In conclusion, there was no relationship between peripheral blood B lymphocytes and disease activity, suggesting that peripheral blood B lymphocytes are not a biomarker of disease activity and therapeutic efficacy in IMN.

Management of idiopathic membranous nephropathy

IMPORTANCE OF THE FIELD

Idiopathic membranous nephropathy (IMN) can have a variable natural course. Treatments able to induce remission can improve the long-term prognosis. However, the optimal therapy for IMN remains controversial.

AREA COVERED IN THIS REVIEW

We reviewed the historical and current literature from 1979 to 2010 regarding the natural course of IMN and the possible treatments giving special emphasis to randomized controlled trials and to more recent approaches.

WHAT THE READER WILL GAIN

The reader will gain a comprehensive review of the available treatments of IMN. A personal therapeutic algorithm for nephrotic patients with IMN is also provided.

TAKE HOME MESSAGE

At least five different treatments showed efficacy in many (but not all) patients with IMN.