Rituximab and minimal change nephrotic syndrome: a therapeutic option

Steroid-resistant nephrotic syndrome as paraneoplastic syndrome of Waldenström macroglobulinemia: a case report

Reports of glomerulonephritis associated with lymphoproliferative disorders are common, but reports of minimal change disease (MCD) accompanying non-Hodgkin's lymphoma are rare. Here, we present a case of a 45-year-old woman diagnosed with primary Waldenström's macroglobulinemia (WM) during MCD treatment. Her kidney biopsy revealed endothelial cell injury in parts of the MCD. Subsequently, she developed steroid-resistant nephrotic syndrome and temporary acute kidney injury, requiring dialysis. Remission of the nephrotic syndrome was achieved after initiating combination therapy with bendamustine and rituximab for WM. The renal histological findings and treatment course suggest a causal relationship between MCD and WM in this case. The pathogenesis of MCD associated with WM may involve the release of glomerular permeability factors derived from B lymphocytes. Although mild WM is often managed with observation, steroid-resistant nephrotic syndrome associated with WM should raise suspicion of a paraneoplastic syndrome, necessitating active chemotherapy targeting WM as a critical treatment approach.

B cell phenotype, activity, and function in idiopathic nephrotic syndrome

Idiopathic nephrotic syndrome (INS) is the most frequent glomerular disease in childhood. However, its underlying etiology mechanism lacks thorough understanding. Previous studies have described INS as a T cell functional disorder resulting in increased plasma lymphocyte-derived permeability factors. In children with frequent relapses of nephrotic syndrome, the mechanism underlying the therapeutic efficacy of CD20 monoclonal antibodies in depleting B cells may provide additional evidence in exploring the critical role of B lymphocytes in INS pathogenesis. Previous studies have proposed that RTX bound to CD20 through antibody-dependent and complement-dependent cytotoxicity and led to lytic clearance of B cells. Additionally, RTX exerted an effect by blocking the interaction between B and T cells or regulating homeostasis and functions of T cell subsets. Recent studies on the development, differentiation, and activation of B-lymphocytes in glomerular diseases have suggested that the B-lymphocytes participate in the INS pathogenesis through interaction with T cells, secretion of antibodies, or production of cytokines. In this study, we aimed to provide a detailed description of the current knowledge on the development, differentiation, activity, functions, and related regulating factors of B cells involved in INS. Thus, further understanding of the immunopathogenesis of INS may offer some opportunities in precisely targeting B cells during therapeutic interventions. IMPACT: The topic "B cells play a role in glomerular disease" is a novel point, which is not completely described previously. We described interactions between T and B cells and immunoglobulin, IgG, IgM, IgE, etc. as well in glomerular disease. The research of regulatory factors associated with B cell's function, like BAFF, is a hot topic in other diseases; however, it is rare in glomerular disease.

Comparison of treatment options in adults with frequently relapsing or steroid-dependent minimal change disease

Background

Studies comparing all treatment options for frequently-relapsing/steroid-dependent (FR/SD) minimal change disease (MCD) in adults are lacking.

Methods

Medical records of 76 adults with FR/SD MCD who were treated with corticosteroids as the first-line therapy were reviewed. Treatment options were compared for the time to relapse, change of therapy and progression (relapse on full-dose treatment).

Results

Second-line treatments included rituximab (RTX; n = 13), mycophenolate mofetil (MMF; n = 12), calcineurin inhibitors (CNI; n = 26) and cyclophosphamide (CTX; n = 16). During the second-line treatments, 48 (71.6%) patients relapsed at median 17 (range 2–100)  months. The majority of relapses occurred during dose tapering or off drug. Twenty of 65 (30.8%) changed therapy after the first relapse. The median time to relapse after the second line was 66 versus 28 months in RTX versus non-RTX groups (P = 0.170). The median time to change of treatment was 66 and 44 months, respectively (P = 0.060). Last-line treatment options included RTX (n = 8), MMF (n = 4), CNI (n = 3) and CTX (n = 2). Seven (41.2%) patients had a relapse during the last-line treatment at median 39 (range 5–112)  months. The median time to relapse was 48 versus 34 months in the RTX versus non-RTX groups (P = 0.727). One patient in the RTX group died presumably of heart failure. No major adverse event was observed. During the median follow-up of 81 (range 9–355)  months, no patients developed end-stage renal disease.

Conclusions

Relapse is frequent in MCD in adults. Patients treated with RTX may be less likely to require a change of therapy and more likely to come off immunosuppressive drugs.

Rituximab versus cyclophosphamide as first steroid-sparing agent in childhood frequently relapsing and steroid-dependent nephrotic syndrome

BACKGROUND

Approximately 50% of children with steroid-sensitive nephrotic syndrome (SSNS) will suffer from frequent relapses or steroid dependency, prompting the use of so-called steroid-sparing drugs. In this pilot study, we compare the efficacy and safety of rituximab to oral cyclophosphamide as first-line steroid-sparing medications.

METHODS

A prospective open-label non-randomized study of children with frequent relapsing or steroid-dependant SSNS. Exclusion criteria were steroid-resistant disease, prescription of immunosuppressive agents other than prednisolone or levamisole, evidence of impaired kidney function, leucopenia, or active infection. The recruited children were allocated either to the oral cyclophosphamide (3 mg/kg/day for 8 weeks) or intravenous rituximab treatment (two doses of 375 mg/m²/dose, 2 weeks apart) and were monitored for relapses and side effects for 12 months.

RESULTS

Forty-six subjects were included from two centers; 27 received cyclophosphamide and 19 received rituximab. One-year relapse-free survival was reached in 17 (58.6%) patients treated with cyclophosphamide compared to 16 (84.2%) with rituximab (adjusted HR 0.36; 95% CI 0.09-1.45; p = 0.151). The mean interval to relapse was 6.9 months in the cyclophosphamide group (N = 10) and 6.3 months in the rituximab group (N = 3). Both treatments were associated with a significant (p < 0.001) reduction in prescribed dose of oral alternate-day steroid from 1.02 to 0.36 mg/kg (cyclophosphamide) and 0.86 to 0.08 mg/kg (rituximab). Importantly, a significantly (p = 0.003) higher percentage of patients achieved complete withdrawal of steroid within 3 months of commencing study treatment in the rituximab (73.7%) versus cyclophosphamide (29.6%) group. Transient leucopenia was the most frequent adverse effect observed in the cyclophosphamide group (18.5%) and one patient (3.4%) had acute hepatotoxicity besides severe leucopenia and neutropenia in the 7th week of treatment with complete recovery with the withdrawal of cyclophosphamide and maintenance of remission. A minor infusion-related reaction in the form of a generalized macular skin rash was observed in one patient (5%) in the rituximab group.

CONCLUSIONS

Rituximab is non-inferior to cyclophosphamide and safe as a first-line steroid-sparing agent in children with SSNS. A larger multicenter study is required to assess superiority over cyclophosphamide. Graphical abstract.

Rituximab as a front-line therapy for adult-onset minimal change disease with nephrotic syndrome

Minimal change disease (MCD) accounts for 15% of adult nephrotic syndrome (NS) cases. Adult-MCD patients may have more severe clinical features than pediatric patients. In children, Rituximab (RTX) has been used since 2006 to treat frequently relapsing NS. In adults, data about the efficacy of RTX for MCD are limited. We report our experience on the use of RTX in adult biopsy-proven MCD. Our series includes 6 adult patients (2 males and 4 females), age 45–73 years, treated with RTX (4 weekly doses of 375 mg/m²). Proteinuria decreased from 11,2 (23–4.8) g/24 hours to 0.6 (0–2) g/24 hours after 6 months, and to 0.4 (0–1, 4) g/24 h in the 4 pts with the longer follow-up. Creatinine decreased from 1.95 (0.5–5) mg/dl to 0.88 (0.6–1.3) mg/l. Five patients achieved a complete renal remission, while in 1 pt proteinuria decreased by 75%. RTX successfully depleted CD19 lymphocytes in 100% of pts for at least 6 months. No clinically relevant adverse events have been observed. This case series shows a remarkable efficacy of RTX in treatment of MCD. RTX can be an attractive alternative both in recurrent forms and in induction-therapy of MCD. RTX may be preferentially used in patients at a high risk of development of the adverse effects of corticosteroids and should be considered as an alternative option in patients with recurrent NS. Additional data are needed to inform clinical practice on how best to use RTX in this patient population, so that definitive randomized trials can be planned.

Loss of the podocyte glucocorticoid receptor exacerbates proteinuria after injury

Nephrotic syndrome is a common disorder in adults and children whose etiology is largely unknown. Glucocorticoids remain the mainstay of therapy in most cases, though their mechanism of action remains poorly understood. Emerging evidence suggests that immunomodulatory therapies used in nephrotic syndrome directly target the podocytes. To study how steroids directly affect the podocytes in the treatment of proteinuria, we created a mouse model with podocyte-specific deletion of the glucocorticoid receptor. The podocyte-specific glucocorticoid receptor (GR) knockout mice had similar renal function and protein excretion compared to wild type. However, after glomerular injury induced by either LPS or nephrotoxic serum, the podocyte GR knockout mice demonstrated worsened proteinuria compared to wild type. Ultrastructural examination of podocytes confirmed more robust foot process effacement in the knockout animals. Expression of several key slit diaphragm protein was down regulated in pGR KO mice. Primary podocytes isolated from wild type and podocyte GR knockout mice showed similar actin stress fiber staining patterns in unstimulated conditions. Yet, when exposed to LPS, GR knockout podocytes demonstrated fewer stress fibers and impaired migration compared to wild type podocytes. We conclude that the podocyte glucocorticoid receptor is important for limiting proteinuria in settings of podocyte injury.

The Evolving Role of Rituximab in Adult Minimal Change Glomerulopathy

BACKGROUND

Minimal-change glomerulopathy is defined histologically by the presence of normal glomeruli on light microscopy and diffuse podocyte effacement on electron microscopy. Although effective in children, corticosteroid treatment in adults is more variable and time to response can be prolonged. Data to support rituximab use in adults with corticosteroid-dependent or resistant minimal-change glomerulopathy are limited. Here, we describe the clinical course of adults with corticosteroid-dependent or -resistant minimal-change glomerulopathy who received rituximab.

METHODS

Demographic and clinical data were collected and analyzed from all adult patients with native kidney, biopsy-proven, minimal-change glomerulopathy who were administered rituximab between 2009 and 2014 and cared for at the UNC Kidney Center.

RESULTS

Ten patients with corticosteroid-resistant (n = 5) or corticosteroid-dependent (n = 5) idiopathic minimal-change glomerulopathy were treated with rituximab between 2009 and 2014. Rituximab treatment induced remission in all 10 patients with a median time to remission of 2 months. The median time from rituximab to corticosteroid discontinuation was 3.5 months. The median remission time was 29 months and follow-up time was 39.5 months. No serious adverse events attributable to rituximab were observed.

CONCLUSION

Rituximab induced remission in all patients with corticosteroid-dependent or -resistant minimal-change glomerulopathy, and may hold great therapeutic potential with good efficacy and minimal toxicity. Mounting evidence implies that a well-conducted randomized controlled clinical trial using rituximab in adults with minimal-change glomerulopathy in both corticosteroid-resistant and corticosteroid-dependent patients is warranted.

Rituximab use in adult primary glomerulopathy: where is the evidence?

Rituximab is a chimeric anti-CD20 antibody that results in depletion of B-cell lymphocytes. It is currently used in the treatment of a variety of autoimmune diseases, in addition to CD20-positive lymphomas. The use of rituximab in the treatment of the adult primary glomerular diseases has emerged recently, although not yet established as first-line therapy in international guidelines. In patients with steroid-dependent minimal change disease or frequently relapsing disease, and in patients with idiopathic membranous nephropathy (IMN), several retrospective and prospective studies support the use of rituximab to induce remission, whereas in idiopathic focal and segmental glomerulosclerosis (FSGS), the use of rituximab has resulted in variable results. Evidence is still lacking for the use of rituximab in patients with immunoglobulin A nephropathy (IgAN) and idiopathic membranoproliferative glomerulonephritis (MPGN), as only few reports used rituximab in these two entities. Randomized controlled trials (RCTs) are warranted and clearly needed to establish the definitive role of rituximab in the management of steroid-dependent and frequently relapsing minimal change disease, IMN, both as first-line and second-line treatment, and in MPGN. We await the results of an ongoing RCT of rituximab use in IgAN. Although current evidence for the use of rituximab in patients with idiopathic FSGS is poor, more RCTs are needed to clarify its role, if any, in the management of steroid-resistant or steroid-dependent FSGS.

The role of the immune system in idiopathic nephrotic syndrome: a review of clinical and experimental studies

Idiopathic nephrotic syndrome (INS) is a multifactorial disease, characterized by proteinuria, hypoalbuminemia, edema and hyperlipidemia. Studies in humans and animal models have associated INS with changes in the immune response. The purpose of this article is to review clinical and experimental findings showing the involvement of the immune response in the pathogenesis of INS. The role of the immune system in INS has been shown by clinical and experimental studies. However, the pattern of immune response in patients with INS is still not clearly defined. Many studies show changes in the dynamics of T lymphocytes, especially the regulatory T cells. Alternatively, there are other reports regarding the involvement of the complement system and B lymphocytes in the pathophysiology of INS. Indeed, none of the immunological biomarkers evaluated were undeniably linked to changes in glomerular permeability and proteinuria. On the other hand, some studies suggest a link between urinary chemokines, such as IL-8/CXCL8 and MCP-1/CCL2, and changes in glomerular permeability and/or the deterioration of glomerulopathies. To understand the pathophysiology of INS, longitudinal studies are clearly needed. The characterization of the profile of the immune response might help the development of specific and individualized therapies, leading to clinical improvement and better prognosis.

A distinct lymphocyte distribution in relapse after rituximab for steroid-dependent nephrotic syndrome

Rituximab (RTX) is a new steroid-sparing therapy for childhood steroid-dependent nephrotic syndrome (NS). However, relapses frequently occur immediately after CD19 recovery. We report the cases of two steroid-dependent NS patients treated with RTX followed by mizoribine (MZB). One patient relapsed, and the other developed proteinuria after CD19 recovery until the MZB was replaced by mycophenolate mofetil. These patients exhibited different lymphocyte phenotypes, with the CD4+/CD8+ profile favoring CD8+ T lymphocytes, while CD3+ HLA-DR-expressing activated T lymphocyte expansion occurred in the relapsed patient. Based on these findings, we suggest that T cell activation may influence outcome and that phenotypic analysis in addition to B cell monitoring may facilitate the detection of NS relapse.

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.

Rituximab is an efficient and safe treatment in adults with steroid-dependent minimal change disease

Development of steroid dependency in patients with nephrotic syndrome may require a long-term multi-drug therapy at risk of drug toxicity and renal failure. Rituximab treatment reduces the steroid dosage and the need for immunosuppressive therapy in pediatric patients. Here we retrospectively analyze the efficacy and safety of rituximab in adult patients with steroid-dependent minimal change disease. To do this, we analyzed the outcome of all adult patients treated with rituximab for steroid-dependent minimal change nephrotic syndrome over a mean follow-up of 29.5 months (range 5.1-82 months). Seventeen patients with steroid-dependent or frequently relapsing minimal change nephrotic syndrome, unresponsive to several immunosuppressive medications, were treated with rituximab. Eleven patients had no relapses after rituximab infusion (mean follow-up 26.7 months, range 5.1-82 months) and nine of them were able to come off all other immunosuppressive drugs and steroids during follow-up. Six patients relapsed at least once after a mean time of 11.9 months (mean follow-up 34.5 months, range 16.9-50.1 months), but their immunosuppressive drug treatment could be stopped or markedly reduced during this time. No adverse events were recorded. Thus, rituximab is efficient and safe in adult patients suffering from severe steroid-dependent minimal change disease. Prospective randomized trials are needed to confirm this study.