Rituximab Treatment for Nephrotic Syndrome in Children

Protective effects of rituximab on puromycin-induced apoptosis, loss of adhesion and cytoskeletal alterations in human podocytes

Podocytes are highly specialized cells playing a key role in the filtration function of the kidney. A damaged podocyte ultrastructure is associated with a reorganization of the actin cytoskeleton and accompanied with a loss of adhesion to the glomerular basement membrane leading to proteinuria in many forms of glomerular diseases, e.g. nephrotic syndrome. If the first-line therapy with glucocorticoids fails, alternative immunosuppressive agents are used, which are known to have the potential to stabilize the actin cytoskeleton. A new option for preventing relapses in steroid dependent nephrotic syndrome is the monoclonal antibody rituximab, which, in addition to its B-cell depleting effect, is assumed to have direct effects on podocytes. We here provide data on the non-immunological off-target effects of the immunosuppressant rituximab on podocyte structure and dynamics in an in vitro puromycin aminonucleoside model of podocyte injury. A conditionally immortalized human podocyte cell line was used. Differentiated podocytes were treated with puromycin aminonucleoside and rituximab. Our studies focussed on analyzing the structure of the actin cytoskeleton, cellular adhesion and apoptosis using immunofluorescence staining and protein biochemistry methods. Treatment with rituximab resulted in a stabilization of podocyte actin stress fibers in the puromycin aminonucleoside model, leading to an improvement in cell adhesion. A lower apoptosis rate was observed after parallel treatment with puromycin aminonucleoside and rituximab visualized by reduced nuclear fragmentation. Consistent with this data, Western-blot analyses demonstrated that rituximab directly affects the caspase pathways by inhibiting the activation of Caspases-8, -9 and -3, suggesting that rituximab may inhibit apoptosis. In conclusion, our results indicate an important role of the immunosuppressant rituximab in terms of stability and morphogenesis of podocytes, involving apoptosis pathways. This could help to improve therapeutical concepts for patients with proteinuria mediated by diseased podocytes.

The outcome of rituximab in treating steroid dependent nephrotic syndrome.: Histopathology and immunosuppressive drugs as predicting factors

OBJECTIVES

To present our experience of treating steroid-dependent nephrotic syndrome (SDNS) in children with repeated doses of rituximab (RTX) with a relatively long follow-up, and to discuss the role of the histopathology type and previous immune-suppressor (IS) drugs on the outcome of these patients.

METHODS

The patients included in this prospective study were children with SDNS who were in remission on a high-dose steroid or with additional IS drugs. All patients underwent renal biopsy before RTX treatment. Intravenous RTX was administered monthly at 375 mg/m² for 4 doses. Response to treatment was defined as maintaining remission with no steroid-sparing agents or prednisone for one year.

RESULTS

Seventeen (14 males) patients were enrolled. Approximately 76% had minimal change disease (MCD) and 3 (18%) patients had immunoglobulin M (IgM) nephropathy. Approximately 85% of MCD and 33% of IgM nephropathy showed complete response to RTX.

CONCLUSION

Compared to other IS used to treat SDNS, RTX showed a significant decrease in relapse rate with fewer side effects. The dose and interval should be modified according to the patient's characteristics, such as medical history, pathology type, and previous IS agents.

Rituximab Use for the Treatment of Childhood Nephrotic Syndrome by Canadian Pediatric Nephrologists: A National Survey

Background:

There is known practice variation in the treatment of frequently relapsing, steroid-dependent, and steroid-resistant nephrotic syndrome in children. Rituximab is an emerging therapy for difficult-to-treat nephrotic syndrome; however, there are no clear treatment guidelines. We therefore hypothesized that a wide variety of approaches to this therapy exist.

Objective:

To evaluate when and how rituximab is used for the treatment of childhood nephrotic syndrome in Canada.

Design and setting:

An online survey was used.

Participants:

Canadian pediatric nephrologists.

Methods:

A cross-sectional survey was distributed across Canada through the Canadian Association of Pediatric Nephrologists (CAPN) to evaluate rituximab treatment practices.

Results:

Of a total of 20 responses, 19 (95%) use rituximab in the treatment of nephrotic syndrome, usually as a third or fourth agent. For the number of rituximab doses, the majority (68%) uses 2 doses each time they use it. Eighteen respondents (90%) measure B cells when using this medication, mostly monthly (50%) or every 3 months (39%). Respondents were administered additional doses of rituximab prophylactically (74%) or at first relapse (47%). Long-term drug safety and drug funding were identified as the main barriers to rituximab use.

Limitations:

This survey represents the practice styles of physicians in a single country, and there is a nonresponse bias of 63%. Also, associations were not calculated.

Conclusions:

Among Canadian pediatric nephrologists, rituximab use for nephrotic syndrome appears to be increasing, but significant practice variations remain, including approaches to B-cell monitoring. It is reserved mostly for second-line and third-line use due to cost, funding issues, and residual uncertainty regarding long-term safety. Understanding these critical areas of practice uncertainty is a first step to optimize treatment of nephrotic syndrome in children.

Successful Pregnancies in a Patient with Childhood-onset Steroid-dependent Nephrotic Syndrome during Rituximab Maintenance Therapy

There are an increasing number of reports on the safe use of rituximab (RTX), a chimeric anti-CD20 monoclonal antibody, in pregnant women with hematological malignancies or refractory autoimmune diseases. In 2014, the use of RTX for patients with complicated steroid-dependent nephrotic syndrome (SDNS) was approved in Japan. We herein report a woman with childhood-onset complicated SDNS due to focal and segmental glomerulosclerosis, who had two successful pregnancies while receiving RTX maintenance therapy. No adverse complications were observed during the pregnancies, and she delivered healthy newborns. This case suggested that RTX may be used safely in pregnant women complicated with SDNS.

Non-corticosteroid immunosuppressive medications for steroid-sensitive nephrotic syndrome in children

BACKGROUND

About 80% of children with steroid-sensitive nephrotic syndrome (SSNS) have relapses. Of these children, half relapse frequently, and are at risk of adverse effects from corticosteroids. While non-corticosteroid immunosuppressive medications prolong periods of remission, they have significant potential adverse effects. Currently, there is no consensus about the most appropriate second-line agent in children who are steroid sensitive, but who continue to relapse. In addition, these medications could be used with corticosteroids in the initial episode of SSNS to prolong the period of remission. This is the fourth update of a review first published in 2001 and updated in 2005, 2008 and 2013.

OBJECTIVES

To evaluate the benefits and harms of non-corticosteroid immunosuppressive medications in SSNS in children with a relapsing course of SSNS and in children with their first episode of nephrotic syndrome.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 10 March 2020 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are 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) or quasi-RCTs were included if they involved children with SSNS and compared non-corticosteroid immunosuppressive medications with placebo, corticosteroids (prednisone or prednisolone) or no treatment; compared different non-corticosteroid immunosuppressive medications or different doses, durations or routes of administration of the same non-corticosteroid immunosuppressive medication.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study eligibility, risk of bias of the included studies and extracted data. Statistical analyses were performed using a random-effects model and results expressed as risk ratio (RR) for dichotomous outcomes or mean difference (MD) for continuous outcomes with 95% confidence intervals (CI). The certainty of the evidence was assessed using GRADE.

MAIN RESULTS

We identified 43 studies (91 reports) and included data from 2428 children. Risk of bias assessment indicated that 21 and 24 studies were at low risk of bias for sequence generation and allocation concealment respectively. Nine studies were at low risk of performance bias and 10 were at low risk of detection bias. Thirty-seven and 27 studies were at low risk of incomplete and selective reporting respectively. Rituximab (in combination with calcineurin inhibitors (CNI) and prednisolone) versus CNI and prednisolone probably reduces the number of children who relapse at six months (5 studies, 269 children: RR 0.23, 95% CI 0.12 to 0.43) and 12 months (3 studies, 198 children: RR 0.63, 95% CI 0.42 to 0.93) (moderate certainty evidence). At six months, rituximab resulted in 126 children/1000 relapsing compared with 548 children/1000 treated with conservative treatments. Rituximab may result in infusion reactions (4 studies, 252 children: RR 5.83, 95% CI 1.34 to 25.29). Mycophenolate mofetil (MMF) and levamisole may have similar effects on the number of children who relapse at 12 months (1 study, 149 children: RR 0.90, 95% CI 0.70 to 1.16). MMF may have a similar effect on the number of children relapsing compared to cyclosporin (2 studies, 82 children: RR 1.90, 95% CI 0.66 to 5.46) (low certainty evidence). MMF compared to cyclosporin is probably less likely to result in hypertrichosis (3 studies, 140 children: RR 0.23, 95% CI 0.10 to 0.50) and gum hypertrophy (3 studies, 144 children: RR 0.09, 95% CI 0.07 to 0.42) (low certainty evidence). Levamisole compared with steroids or placebo may reduce the number of children with relapse during treatment (8 studies, 474 children: RR 0.52, 95% CI 0.33 to 0.82) (low certainty evidence). Levamisole compared to cyclophosphamide may make little or no difference to the risk for relapse after 6 to 9 months (2 studies, 97 children: RR 1.17, 95% CI 0.76 to 1.81) (low certainty evidence). Cyclosporin compared with prednisolone may reduce the number of children who relapse (1 study, 104 children: RR 0.33, 95% CI 0.13 to 0.83) (low certainty evidence). Alkylating agents compared with cyclosporin may make little or no difference to the risk of relapse during cyclosporin treatment (2 studies, 95 children: RR 0.91, 95% CI 0.55 to 1.48) (low certainty evidence) but may reduce the risk of relapse at 12 to 24 months (2 studies, 95 children: RR 0.51, 95% CI 0.35 to 0.74), suggesting that the benefit of the alkylating agents may be sustained beyond the on-treatment period (low certainty evidence). Alkylating agents (cyclophosphamide and chlorambucil) compared with prednisone probably reduce the number of children, who experience relapse at six to 12 months (6 studies, 202 children: RR 0.44, 95% CI 0.32 to 0.60) and at 12 to 24 months (4 studies, 59 children: RR 0.20, 95% CI 0.09 to 0.46) (moderate certainty evidence). IV cyclophosphamide may reduce the number of children with relapse compared with oral cyclophosphamide at 6 months (2 studies, 83 children: RR 0.54, 95% CI 0.34 to 0.88), but not at 12 to 24 months (2 studies, 83 children: RR 0.99, 95% CI 0.76 to 1.29) and may result in fewer infections (2 studies, 83 children: RR 0.14, 95% CI 0.03 to 0.72) (low certainty evidence). Cyclophosphamide compared to chlorambucil may make little or no difference in the risk of relapse after 12 months (1 study, 50 children: RR 1.31, 95% CI 0.80 to 2.13) (low certainty evidence).

AUTHORS' CONCLUSIONS

New studies incorporated in this review indicate that rituximab is a valuable additional agent for managing children with steroid-dependent nephrotic syndrome. However, the treatment effect is temporary, and many children will require additional courses of rituximab. The long-term adverse effects of this treatment are not known. Comparative studies of CNIs, MMF, levamisole and alkylating agents have demonstrated little or no differences in efficacy but, because of insufficient power; clinically important differences in treatment effects have not been completely excluded.

Difficult-to-treat idiopathic nephrotic syndrome: established drugs, open questions and future options

The idiopathic nephrotic syndrome in childhood can be classified according to the International Study of Kidney Disease in Children (ISKDC) based on the response to steroids. Typically, steroid-sensitive nephrotic syndrome (SSNS) is characterised by minimal changes in disease (MCD) histology, whereas in steroid-resistant nephrotic syndrome (SRNS) focal segmental glomerulosclerosis (FSGS) is the most prevalent lesion. Patients with SSNS may develop frequent relapses and/or steroid dependency, which can be difficult to treat. New studies confirm the value of calcineurin inhibitors (CNIs) and mycophenolic acid in preventing relapses of SSNS. Rituximab also plays an important role, but many questions regarding initial dosing, repetitions of courses, and long-term side effects remain unclear. SRNS, especially when unresponsive to treatment, can lead to chronic kidney disease. In particular, treatment with CNIs has improved the prognosis and recent data indicate that treatment can even be discontinued in many patients with full remission. In CNI-unresponsive SRNS, rituximab is less effective than in SSNS and the role of other biologicals (such as ofatumumab, abatacept, and others) remains unclear. A significant proportion of children with FSGS have genetic causes and most patients do not respond to immunosuppression, although individual patients with partial and even complete response have been documented. Future studies should evaluate treatments leading to long-term remission without maintenance immunosuppression in SSNS; in both genetic and immune-mediated SRNS, novel options to decrease the number of treatment-unresponsive patients seem mandatory, as they are at a high risk of developing end-stage renal disease.

Rituximab in children with steroid-dependent nephrotic syndrome: experience of a tertiary center and review of the literature

OBJECTIVES

Rituximab (RTX) is a new treatment option in children with difficult-to-treat steroid-dependent nephrotic syndrome (SDNS). We evaluated the experience of our tertiary center and reviewed the current literature.

METHODS

This is a retrospective single-center study evaluating the efficacy and safety of RTX in children with difficult-to-treat SDNS. Age at diagnosis, type and duration of immunosuppression, age at administration, dose of RTX, possible adverse events, number of relapses, duration of remission, and B-cell count after administration of RTX were analyzed.

RESULTS

Nine children with a median age at diagnosis of nephrotic syndrome of 4.75 (range 1.33-11.33) years and a median age at administration of RTX of 16.08 (range 3.33-19.25) years were included. Before administration of RTX they had a median number of relapses per year of 1.70 (range 0.82-4.80). At last follow-up (median 2.75 years, range 0.58-3.92), a reduction in the number of relapses per year to 0.26 (range 0-2.18) was noted, despite cessation or lowering the dose of immunosuppressive therapy. Four patients achieved complete remission after the first administration of RTX, four more patients after subsequent doses of RTX. No severe adverse events were noted.

CONCLUSION

RTX was an effective and safe therapeutic option in our cohort of children with difficult-to-treat SDNS, resulting in a significant reduction of yearly relapses in the absence of severe adverse events and facilitating the reduction of other immunosuppressive medication.

New biologics in the treatment of rare glomerular diseases of childhood

Minimal change disease and focal segmental glomerulosclerosis are rare but important causes of end-stage kidney disease in children. Though their pathogenesis is still unclear, evidence of immune abnormalities provided the background for the use of immunosuppressive drugs, such as corticosteroids, calcineurin inhibitors, antiproliferative and alkylating agents. Unfortunately, these treatments fail to achieve a sustained remission in a significant portion of patients and are burdened by significant toxicities. Recent developments of new biologics, including anti-CD20 monoclonal antibodies rituximab and ofatumumab, offered the opportunity to selectively target immune cell subsets or activation pathways, leading to more effective and safer hypothesis-driven treatments.

Rituximab for nephrotic syndrome in children

Idiopathic nephrotic syndrome is the most common chronic glomerular disease in children. At least 20 % of children with this syndrome show frequent relapses and/or steroid dependence during or after immunosuppressive therapies, a condition defined as complicated frequently relapsing/steroid-dependent nephrotic syndrome (FRNS/SDNS). Approximately 1-3 % of children with idiopathic nephrotic syndrome are resistant to steroids and all immunosuppressive agents, a condition defined as refractory steroid-resistant nephrotic syndrome (SRNS); these SRNS children have a high risk of end-stage renal failure. Rituximab, a chimeric anti-CD20 monoclonal antibody, has been shown to be effective for patients with complicated FRNS/SDNS and refractory SRNS. This review describes the recent results of rituximab treatment applied to pediatric nephrotic syndrome, as well as those of our recent study, a multicenter, double-blind, randomized, placebo-controlled trial of rituximab for childhood-onset complicated FRNS/SDNS (RCRNS01). The overall efficacy and safety of rituximab for this disease are discussed.

Efficacy of leflunomide combined with prednisone in the treatment of refractory nephrotic syndrome

OBJECTIVE

To assess the safety and clinical efficacy of leflunomide (LEF) and prednisone on refractory nephrotic syndrome (RNS).

METHODS

A total of 52 patients with RNS were treated for 24 weeks between 2010 and 2014 in our hospital. In the treated group, 26 patients were treated with LEF and prednisone, and, in the control group, 26 patients were treated with cyclophosphamide (CTX) and prednisone. During the treatment, 24 h urinary protein excretion and the serum levels of albumin and cholesterol, and kidney function were assayed before and after the therapy. Adverse reactions during treatment were recorded.

RESULTS

In the LEF group, the medication was markedly effective in eight cases and effective in nine cases; the total efficacy rate was 65.30%. In the CTX group, the treatment was markedly effective in six cases and effective in nine cases; the total efficacy rate was 57%. There were no significant differences between the results of the total efficacy rate (p > .05). The 24 h urinary protein excretion and serum cholesterol levels in both groups decreased after therapy and the serum levels of albumin in both groups increased after therapy. There were significant differences between the results for the 24 h urinary protein excretion, serum levels of albumin and cholesterol in the two groups (p < .05). The treatments were well tolerated in both groups.

CONCLUSION

LEF combined with prednisone has a certain efficacy on the RNS and displays few adverse reactions. A large-sample, randomized double-blind controlled study and long-term follow-up are needed to verify the efficacy of LEF combined with prednisone.

Pathogenesis of minimal change nephrotic syndrome: an immunological concept

Idiopathic nephrotic syndrome (INS) in children is characterized by massive proteinuria and hypoalbuminemia. Minimal change nephrotic syndrome (MCNS) is the most common form of INS in children. The pathogenesis of MCNS still remains unclear, however, several hypotheses have been recently proposed. For several decades, MCNS has been considered a T-cell disorder, which causes the impairment of the glomerular filtration barrier with the release of different circulating factors. Increased levels of several cytokines are also suggested. Recently, a "two-hit" theory was proposed that included the induction of CD80 (B7-1) and regulatory T-cell (Treg) dysfunction, with or without impaired autoregulatory functions of the podocyte. In contrast to the well-established involvement of T cells, the role of B cells has not been clearly identified. However, B-cell biology has recently gained more attention, because rituximab (a monoclonal antibody directed against CD20-bearing cells) demonstrated a very good therapeutic response in the treatment of childhood and adult MCNS. Here, we discuss recent insights into the pathogenesis of MCNS in children.