Treatment of steroid and cyclosporine-resistant idiopathic nephrotic syndrome in children

Serum albumin level is associated with mycophenolic acid concentration in children with idiopathic nephrotic syndrome

Mycophenolate mofetil is effective for the treatment of pediatric idiopathic nephrotic syndrome (INS). The dosage of mycophenolate mofetil is adjusted according to the serum concentration of mycophenolic acid (MPA). Kidney function or cyclosporine (CsA) concentrations affect serum MPA levels. However, few studies have focused on the association between serum concentrations of MPA and albumin. This retrospective observational study aimed to evaluate the relationship between the serum concentrations of MPA and albumin in INS children. Subjects were children with INS who underwent the therapeutic drug monitoring of CsA and MPA. We obtained the serum albumin (sAlb) concentration, estimated glomerular filtration rate (eGFR), age, and MPA and CsA areas under concentration-time curves from 0 to 12 h (AUC_0-12). Multiple linear regression analysis and generalized estimating equations were performed to predict values for MPA AUC_0-12. We obtained information for 51 INS children with 261 MPA AUC_0-12 measurements. The standardized regression coefficients of sAlb, eGFR, CsA AUC_0-12, and age were 0.54, - 0.21, - 0.07, and 0.04, respectively. Furthermore, MPA AUC_0-12 levels positively correlated with sAlb concentrations (p < 0.001) and were inversely correlated with eGFR values (p = 0.005) but not with CsA AUC_0-12 (p = 0.24) and age (p = 0.65).Conclusion: Serum albumin concentration was strongly associated with total MPA concentration compared with kidney function or CsA values. Although patients with INS may have a low serum concentration of total MPA in the presence of low sAlb concentration, close attention should be paid to the interpretation of the low MPA values. What is Known: • The dosage of mycophenolate mofetil is adjusted according to the serum concentration of total mycophenolic acid. • Kidney function, cyclosporin concentrations, or serum albumin concentrations influence serum mycophenolic acid levels. What is New: • Serum albumin concentration is more strongly associated with total mycophenolic acid concentration than kidney function or cyclosporin values. • In children with nephrotic syndrome, the total mycophenolic acid concentration may not increase in the presence of severe hypoalbuminemia.

Current understandings in treating children with steroid-resistant nephrotic syndrome

Steroid-resistant nephrotic syndrome (SRNS) remains a challenge for paediatric nephrologists. SRNS is viewed as a heterogeneous disease entity including immune-based and monogenic aetiologies. Because SRNS is rare, treatment strategies are individualized and vary among centres of expertise. Calcineurin inhibitors (CNI) have been effectively used to induce remission in patients with immune-based SRNS; however, there is still no consensus on treating children who become either CNI-dependent or CNI-resistant. Rituximab is a steroid-sparing agent for patients with steroid-sensitive nephrotic syndrome, but its efficacy in SRNS is controversial. Recently, several novel monoclonal antibodies are emerging as treatment option, but their efficacy remains to be seen. Non-immune therapies, such as angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, have been proven efficacious in children with SRNS and are recommended as adjuvant agents. This review summarizes and discusses our current understandings in treating children with idiopathic SRNS.

Mycophenolate mofetil for sustained remission in nephrotic syndrome

The clinical application of mycophenolate mofetil (MMF) has significantly widened beyond the prophylaxis of acute and chronic rejections in solid organ transplantation. MMF has been recognized as an excellent treatment option in many immunologic glomerulopathies. For children with frequently relapsing nephrotic syndrome (FRNS) or steroid-dependent nephrotic syndrome (SDNS) experiencing steroid toxicity, MMF has been recommended as a steroid-sparing drug. Uncontrolled studies in patients with FRNS and SDSN have shown that many patients can achieve sustained remission of proteinuria with MMF monotherapy. Three randomized controlled trials have similarly demonstrated that MMF is beneficial in these patients, but less effective than the calcineurin inhibitors cyclosporin A or tacrolimus. Some, but not all, patients with steroid-resistant nephrotic syndrome (SRNS) may also respond to MMF, usually given in combination with other drugs, with partial or complete remission. There are important limitations to the interpretation and comparability of these studies including study design, sample size, patient selection, clinical endpoints, carry-over effects, and duration of follow-up. In all studies, MMF had relatively few side effects, no nephrotoxicity, or no systemic toxicity. MMF is teratogenic, and contraceptive advice is required in females. There is a poor correlation between MMF dose and mycophenolic acid (MPA) exposure and significant inter- and intra-patient variability in drug pharmacokinetics. A higher estimated MPA-AUC_0-12 target range than recommended for pediatric renal transplant recipients is essential to prevent relapses. Therefore, therapy should be guided by drug monitoring to avoid relapses. Further studies are needed to test the efficacy of MMF in inducing remission and, as part of a combination therapy, achieving sustained remission in patients with SRNS.

Mycophenolate mofetil is inferior to tacrolimus in sustaining remission in children with idiopathic steroid-resistant nephrotic syndrome

Studies of nephrotic syndrome show that substitution of calcineurin inhibitors by mycophenolate mofetil (MMF) enables sustained remission and corticosteroid sparing and avoids therapy associated adverse effects. However, controlled studies in patients with steroid resistance are lacking. Here we examined the effect of switching from therapy with tacrolimus to MMF on disease course in an open-label, one-to-one randomized, controlled trial on children (one to 18 years old), recently diagnosed with steroid-resistant nephrotic syndrome, at a referral center in India. Following six months of therapy with tacrolimus, patients with complete or partial remission were randomly assigned such that 29 received MMF while 31 received tacrolimus along with tapering prednisolone on alternate days for 12 months. On intention-to-treat analyses, the proportion of patients with a favorable outcome (sustained remission, infrequent relapses) at one year was significantly lower (44.8%) in the MMF group than in the tacrolimus group (90.3%). The incidence of relapses was significantly higher for patients treated with MMF than tacrolimus (mean difference: 1.05 relapses per person-year). While there was no difference in the proportion of patients with sustained remission, the risk of recurrence of steroid resistance was significantly higher for patients receiving MMF compared to tacrolimus (mean difference: 20.7%). Compared to tacrolimus, patients receiving MMF had a significantly (71%) lower likelihood of a favorable outcome and significantly increased risk of treatment failure (frequent relapses, steroid resistance). Thus, replacing tacrolimus with MMF after six months of tacrolimus therapy for steroid-resistant nephrotic syndrome in children is associated with significant risk of frequent relapses or recurrence of resistance. These findings have implications for guiding the duration of therapy with tacrolimus for steroid-resistant nephrotic syndrome.

Cyclosporine in the treatment of childhood idiopathic steroid resistant nephrotic syndrome: a single centre experience in Nigeria

Introduction

Children with steroid resistant nephrotic syndrome usually require treatment with second-line agents and calcineurin inhibitors such as cyclosporine are now recommended as initial therapy. These agents only recently become available in our environment and their impact on care is unknown. We reviewed the short-term treatment outcomes of their use in comparison with previous outcomes.

Methods

Medical records of children managed for idiopathic steroid resistant nephrotic syndrome over a 5 year period were reviewed. Remission rates and improvement in renal function following use of various agents were compared.

Results

Of 103 children with idiopathic nephrotic syndrome, 25(24.3%) were steroid resistant, of whom 17 received additional medications. Full remission rate for cyclosporine was 70% (7/10). Remission rates prior to the availability of cyclosporine were 40% (2/5) for cyclophosphamide and 66% (2/3), (partial remission only) with enalapril, an angiotensin converting enzyme inhibitor used in combination with alternate day prednisolone. One child with cyclophosphamide resistance subsequently achieved remission with cyclosporine. Remission was not related to sex (p=0.96), age (p=0.54), serum albumin (p=0.37) or hypertension (p=0.43) but to serum cholesterol (p= 0.02). The estimated glomerular filteration rate (eGFR) among children treated with cyclosporine ranged from 30-167 ml/min/1.73m² as follows: >90 (5); 60-89 (3); 30-59 (2) while the mean pre and post treatment eGFR in those with eGFR <90 were 60 and 104ml/min/1.73m² respectively (p=0.03). Mortality rate was 10% (1/10) in children treated with cyclosporine compared with 28.6% (2/7) in those treated with other medications (p=0.54).

Conclusion

Cyclosporine resulted in improved treatment outcomes in children with idiopathic steroid resistant nephrotic syndrome.

Immunosuppressive therapy in children with steroid-resistant, frequently-relapsing, and steroid-dependent idiopathic nephrotic syndrome: a single center experience

Introduction

Immunosuppressive agents are recommended for the management of children with steroid-resistant (SRNS), frequently-relapsing (FRNS), and steroid-dependent idiopathic nephrotic syndrome (SDNS). This study evaluated the efficacy of immunosuppressive agents in these cases.

Methods

This is a retrospective analysis of the records of 130 pediatric cases recruited from a tertiary-care center over a period of two years. They were divided into two groups: 51 patients with SRNS (Group I) and 79 cases with SDNS and FRNS (Group II). They were treated with immunosuppressive agents in addition to steroids, either as double- or triple-combination therapy. Complete or partial remission was considered a good response.

Results

In group I, the proportions of good response to cyclophosphamide, cyclosporine A, and mycophenolate mofetil were 48.6, 60, and 80%, respectively (p = 0.162). In group II, the resistance rate was significantly higher with levamisole than with cyclophosphamide and azathioprine (p = 0.046). Leukopenia was reported infrequently after the administration of cyclophosphamide or azathioprine. The most serious adverse reaction was to cyclosporine A, which induced nephrotoxicity (6.4%), while no adverse effects related to levamisole were reported. Histopathological diagnoses were available in only 39 patients.

Conclusion

The high potency of cyclosporine with steroids recommends its use in patients with idiopathic SRNS with a normal glomerular filtration rate. Its efficacy is augmented when combined with mycophenolate mofetil. Cyclophosphamide, orally or as intravenous boluses, together with alternate-day steroids, could be a good option outside the peripubertal age. The outcomes of FRNS and SDNS could be improved by encouraging compliance with the use of levamisole.

Osthole improves an accelerated focal segmental glomerulosclerosis model in the early stage by activating the Nrf2 antioxidant pathway and subsequently inhibiting NF-κB-mediated COX-2 expression and apoptosis

Inflammatory reactions and oxidative stress are implicated in the pathogenesis of focal segmental glomerulosclerosis (FSGS), a common chronic kidney disease with relatively poor prognosis and unsatisfactory treatment regimens. Previously, we showed that osthole, a coumarin compound isolated from the seeds of Cnidium monnieri, can inhibit reactive oxygen species generation, NF-κB activation, and cyclooxygenase-2 expression in lipopolysaccharide-activated macrophages. In this study, we further evaluated its renoprotective effect in a mouse model of accelerated FSGS (acFSGS), featuring early development of proteinuria, followed by impaired renal function, glomerular epithelial cell hyperplasia lesions (a sensitive sign that precedes the development of glomerular sclerosis), periglomerular inflammation, and glomerular hyalinosis/sclerosis. The results show that osthole significantly prevented the development of the acFSGS model in the treated group of mice. The mechanisms involved in the renoprotective effects of osthole on the acFSGS model were mainly a result of an activated Nrf2-mediated antioxidant pathway in the early stage (proteinuria and ischemic collapse of the glomeruli) of acFSGS, followed by a decrease in: (1) NF-κB activation and COX-2 expression as well as PGE2 production, (2) podocyte injury, and (3) apoptosis. Our data support that targeting the Nrf2 antioxidant pathway may justify osthole being established as a candidate renoprotective compound for FSGS.