Long-term outcome of children with steroid-resistant nephrotic syndrome treated with tacrolimus

Urinary Neutrophil Gelatinase Associated Lipocalin: A Novel Biomarker Determining Steroid Responsiveness in Nephrotic Syndrome

BACKGROUND

Urinary Neutrophil Gelatinase Associated Lipocalin (uNGAL) has been demonstrated to be a powerful marker of progression in chronic kidney disease. The present study was done to find out the ability of uNGAL as a biomarker to differentiate steroid-sensitive nephrotic syndrome (SSNS), steroid-dependent nephrotic syndrome (SDNS), and steroid-resistant nephrotic syndrome (SRNS) from each other.

METHOD

The cross-sectional study included 45 patients with Idiopathic Nephrotic Syndrome (INS) (15 each of SSNS, SDNS, and SRNS). uNGAL was measured by ELISA. Demographic profile of patients with INS, lab parameters including Serum albumin, cholesterol, urinary albumin, creatinine, etc., were estimated using standard laboratory methods. Various statistical methods were used to assay the usefulness of NGAL as a diagnostic marker.

RESULTS

Among the three groups, the median value of uNGAL was 8.68 ng/ml in SSNS, higher in SDNS (32.8 ng/ml), and highest in the SRNS group (50 ng/ml). The receiver operating curve (ROC) was generated for uNGAL to differentiate between SDNS and SSNS. Cut-off 13.26 ng/ml had a sensitivity of 86.7% and specificity of 97.4%, PPV 92.9%, and NPV 87.5 % with an area under the curve (AUC) of 0.958. Another ROC was generated for uNGAL to differentiate between SRNS and SDNS, and cut-off 40.02 ng/ml had a sensitivity of 80% and specificity of 86.7% with an AUC of 0.907. A similar result was observed when ROC was generated to differentiate SRNS from SSNS and SDNS combined.

CONCLUSION

uNGAL can distinguish between SSNS, SDNS, and SRNS.

Efficacy and Safety of Immunosuppressive Therapy in Primary Focal Segmental Glomerulosclerosis: A Systematic Review and Meta-analysis

Rationale & Objective

Focal segmental glomerulosclerosis (FSGS) is a rare condition that can lead to kidney function decline and chronic kidney failure. Immunosuppressants are used to treat primary FSGS. However, their efficacy and safety in FSGS are not clearly established. We assessed current knowledge on clinical effectiveness and safety of immunosuppressants for primary FSGS.

Study Design

Systematic review of randomized controlled trials, interventional nonrandomized controlled trials, observational studies, retrospective studies, and registries.

Setting & Participants

Patients with primary and genetic FSGS.

Selection Criteria for Studies

Medline, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for English-language, primary-FSGS studies from inception to 2019. Clinical outcomes were changes from baseline in proteinuria, kidney function, and kidney survival.

Data Extraction

2 investigators independently screened studies and extracted data.

Analytical Approach

Study results were summarized using random-effects models either as ratios of means between follow-up and baseline measurements or as HRs.

Results

We included 98 articles. Substantial heterogeneity was observed in patient baseline characteristics and study designs. Most studies assessed treatment with corticosteroids alone or combined with other drugs, mainly immunosuppressants. Patients treated with immunosuppressants showed reduced proteinuria (14 studies; ratio of means, 0.36; 95% CI, 0.20-0.47), decreased creatinine clearance (mean difference, −25.03; 95% CI, −59.33 to −9.27) and (significantly) lower estimated glomerular filtration rates (mean difference, −7.61 mL/min/1.73 m²; 95% CI, −14.98 to 0.25 mL/min/1.73 m²). Immunosuppressant therapy had an uncertain effect on reducing the chronic kidney failure risk. Hypertension and infections were the most commonly reported adverse events.

Limitations

Heterogeneity in study designs, patient populations, and treatment regimens; no access to individual patient–level data.

Conclusions

This systematic review supports proteinuria reduction with immunosuppressant therapy in primary FSGS over varying follow-up periods. The effects of immunosuppressants on kidney survival remain uncertain. This review underscores the need for better-designed and adequately controlled studies to assess immunosuppressant therapy in patients with primary FSGS.

Management of Steroid-Resistant Nephrotic Syndrome in Children

Nephrotic syndrome (NS) affects 115-169 children per 100,000, with rates varying by ethnicity and location. Immune dysregulation, systemic circulating substances, or hereditary structural abnormalities of the podocyte are considered to have a role in the etiology of idiopathic NS. Following daily therapy with corticosteroids, more than 85% of children and adolescents (often aged 1 to 12 years) with idiopathic nephrotic syndrome have full proteinuria remission. Patients with steroid-resistant nephrotic syndrome (SRNS) do not demonstrate remission after four weeks of daily prednisolone therapy. The incidence of steroid-resistant nephrotic syndrome in children varies between 35 and 92 percent. A third of SRNS patients have mutations in one of the important podocyte genes. An unidentified circulating factor is most likely to blame for the remaining instances of SRNS.

The aim of this article is to explore and review the genetic factors and management of steroid-resistant nephrotic syndrome. An all language literature search was conducted on MEDLINE, COCHRANE, EMBASE, and Google Scholar till September 2021. The following search strings and Medical Subject Headings (MeSH) terms were used: “Steroid resistance”, “nephrotic syndrome”, “nephrosis” and “hypoalbuminemia”. We comprehensively reviewed the literature on the epidemiology, genetics, current treatment protocols, and management of steroid-resistant nephrotic syndrome.

We found that for individuals with non-genetic SRNS, calcineurin inhibitors (cyclosporine and tacrolimus) constitute the current mainstay of treatment, with around 70% of patients achieving full or partial remission and an acceptable long-term prognosis. Patients with SRNS who do not react to calcineurin inhibitors or other immunosuppressive medications may have deterioration in kidney function and may develop end-stage renal failure. Nonspecific renal protective medicines, such as angiotensin-converting enzyme inhibitors, angiotensin 2 receptor blockers, and anti-lipid medications, slow the course of the illness. Recurrent focal segmental glomerulosclerosis in the allograft affects around a third of individuals who get a kidney transplant, and it frequently responds to a combination of plasma exchange, rituximab, and increased immunosuppression. Despite the fact that these results show a considerable improvement in outcome, further multicenter controlled studies are required to determine the optimum drugs and regimens to be used.

Therapeutic Response and Long-Term Renal Outcomes in Childhood Idiopathic Steroid-Resistant Nephrotic Syndrome: A Single-Center Study

<b><i>Purpose:</i></b> We aimed to evaluate therapeutic response and long-term renal outcomes of childhood idiopathic steroid-resistant nephrotic syndrome (iSRNS). <b><i>Methods:</i></b> We retrospectively reviewed treatment regimens, especially calcineurin inhibitor (CNI), pathologic diagnoses, and long-term renal outcomes of iSRNS patients for 30 years. <b><i>Results:</i></b> Of 516 patients with idiopathic NS, 52 (10.1%) had iSRNS. Renal biopsies from 48 patients showed minimal change disease (MCD) in 23 (47.9%), focal segmental glomerulosclerosis in 24 (50.0%), and mesangioproliferative glomerulonephritis in 1 (2.1%). The median follow-up period was 66.5 (range, 4–275) months, and 90.4% of them were treated with a CNI. CNI induced remission in 70.2% within 50.4 ± 43.5 days. Of the patients with MCD and focal segmental glomerular sclerosis (FSGS), 86.4% (19/22) and 45.0% (9/20) (<i>p =</i> 0.005) responded to CNI, respectively. Mean time until remission after using CNI was longer with FSGS (90.4 ± 54.0 days) than with MCD (29.6 ± 26.3 days) (<i>p =</i> 0.010). CNI-responsive patients with FSGS or MCD showed preserved renal function, and CNI nonresponsive MCD patients also showed preserved renal function during follow-up. However, end-stage renal disease (ESRD) progressed in 8 out of 11 patients with FSGS nonresponsive to the CNI for an average of 44.9 ± 18.4 months after diagnosis. <b><i>Conclusion:</i></b> Different response rates and times for remission were achieved with the CNI according to the pathology of iSRNS. All MCD patients regardless of CNI response and all CNI-responsive patients with FSGS showed excellent renal outcomes, while almost all FSGS patients nonresponsive to CNI eventually progressed to ESRD.

Early Prediction of Tacrolimus-Induced Tubular Toxicity in Pediatric Refractory Nephrotic Syndrome Using Machine Learning

Background and Aims: Tacrolimus(TAC)-induced nephrotoxicity, which has a large individual variation, may lead to treatment failure or even the end-stage renal disease. However, there is still a lack of effective models for the early prediction of TAC-induced nephrotoxicity, especially in nephrotic syndrome(NS). We aimed to develop and validate a predictive model of TAC-induced tubular toxicity in children with NS using machine learning based on comprehensive clinical and genetic variables. Materials and Methods: A retrospective cohort of 218 children with NS admitted between June 2013 and December 2018 was used to establish the models, and 11 children were prospectively enrolled for external validation. We screened 47 clinical features and 244 genetic variables. The changes in urine N- acetyl- β-D- glucosaminidase(NAG) levels before and after administration was used as an indicator of renal tubular toxicity. Results: Five machine learning algorithms, including extreme gradient boosting (XGBoost), gradient boosting decision tree (GBDT), extremely random trees (ET), random forest (RF), and logistic regression (LR) were used for model generation and validation. Four genetic variables, including TRPC6 rs3824934_GG, HSD11B1 rs846910_AG, MAP2K6 rs17823202_GG, and SCARB2 rs6823680_CC were incorporated into the final model. The XGBoost model has the best performance: sensitivity 75%, specificity 77.8%, accuracy 77.3%, and AUC 78.9%. Conclusion: A pre-administration model with good performance for predicting TAC-induced nephrotoxicity in NS was developed and validated using machine learning based on genetic factors. Physicians can estimate the possibility of nephrotoxicity in NS patients using this simple and accurate model to optimize treatment regimen before administration or to intervene in time after administration to avoid kidney damage.

Population pharmacokinetics model and initial dose optimization of tacrolimus in children and adolescents with lupus nephritis based on real-world data

The present study aimed to establish a population pharmacokinetics model of tacrolimus and further optimize the initial dosing regimen of tacrolimus in pediatric and adolescent patients with lupus nephritis (LN). Pediatric and adolescent patients with LN were recruited between August 2014 and September 2019 at the Children's Hospital of Fudan University (Shanghai, China). Relevant information was used to set up a population pharmacokinetics model with a Nonlinear Mixed Effect Model and the initial dosage regimen was simulated with the Monte Carlo method. Body weight and co-administration of wuzhi capsule were indicated to influence tacrolimus clearance in pediatric and adolescent patients with LN, and at the same body weight, the rate of tacrolimus clearance in patients without vs. with co-administration of wuzhi capsule was 1:0.71. In addition, in patients who were not administered wuzhi capsule, an initial dosage regimen of 0.15 mg/kg/day was recommended for a body weight of 10-23 kg and 0.10 mg/kg/day for 23-60 kg; in patients who were administered wuzhi capsule, an initial dosage regimen of 0.10 mg/kg/day was recommended for a body weight of 10-23 kg and 0.05 mg/kg/day for 23-60 kg. To the best of our knowledge, the present study was the first to establish a population pharmacokinetics model of tacrolimus in order to determine the optimal initial dosage regimen of tacrolimus in pediatric and adolescent patients with LN.

Off-label use of tacrolimus in children with glomerular disease: Effectiveness, safety and pharmacokinetics

Glomerular diseases are leading causes of end-stage renal disease in children. Tacrolimus is frequently used off-label in the treatment of glomerular diseases. The effectiveness, safety and pharmacokinetic data of tacrolimus in the treatment of glomerular diseases in children are reviewed in this paper to provide evidence to support its rational use in clinical practice. The remission rates in previously published studies were different. In 19 clinical trials on children with nephrotic syndrome, the overall remission rate was 52.6-97.6%. In four clinical trials on children with lupus nephritis, the overall remission rate was 81.8-89.5%. In a pilot study with paediatric Henoch-Schönlein purpura nephritis patients, the overall remission rate was 100.0%. Infection, nephrotoxicity, gastrointestinal symptoms and hypertension are the most common adverse events. Body weight, age, CYP3A5 genotype, cystatin-C and daily dose of tacrolimus may have significant effects on the pharmacokinetics of tacrolimus in children with glomerular disease. More prospective controlled trials with long follow-up are needed to demonstrate definitely the effectiveness, safety and pharmacokinetics of tacrolimus in children with glomerular diseases.

Risk factors and clinical characteristics of tacrolimus-induced acute nephrotoxicity in children with nephrotic syndrome: a retrospective case-control study

PURPOSE

Acute nephrotoxicity is a common adverse reaction of tacrolimus therapy; however, its risk factors in pediatric nephrotic syndrome (NS) remain to be evaluated. The objective of this study was to investigate the risk factors and characteristics of tacrolimus-induced acute nephrotoxicity in children with NS.

METHODS

Past records of children with NS admitted to our hospital from 2014 to 2018 were reviewed. The incidence and characteristics of nephrotoxicity were analyzed. Multivariate logistic regression analysis was used to identify the risk factors of nephrotoxicity. A clinically applicable risk score was developed and validated.

RESULTS

Tacrolimus-induced nephrotoxicity occurred in 25 of 129 patients, 13 patients were grade 1, and the renal function was recovered in 22 patients. Multivariate regression analysis showed that the maximum trough concentrations (C_12h) of tacrolimus (OR, 1.48; 95% CI, 1.16 to 1.88; P < 0.001), huaiqihuang granules (OR, 0.095; 95% CI, 0.014 to 0.66; P = 0.017), and diarrhea (OR, 22.00; 95% CI, 1.58 to 306.92; P = 0.022) were independently associated with tacrolimus-induced nephrotoxicity. The maximum C_12h were significantly higher in patients with nephrotoxicity (median 9.0 ng/ml) and the cut-off value for acute nephrotoxicity was 6.5 ng/ml. The area under the receiver operating characteristic curve was 0.821 for the proposed model based on the observations used to create the model and 0.817 obtained from k-fold cross-validation.

CONCLUSIONS

High trough concentration of tacrolimus and diarrhea can potentiate the risk of tacrolimus-induced acute nephrotoxicity in children with NS, while huaiqihuang granules can protect this condition.

Population pharmacokinetics of tacrolimus in pediatric refractory nephrotic syndrome and a summary of other pediatric disease models

Different tacrolimus (TAC) population pharmacokinetic (PPK) models have been established in various pediatric disease populations. However, a TAC PPK model for pediatric refractory nephrotic syndrome (PRNS) has not been well characterized. The current study aimed to establish a TAC PPK model in Chinese PRNS and provide a summary of previous literature concerning TAC PPK models in different pediatric diseases. A total of 147 TAC conventional therapeutic drug monitoring (TDM) data from multiple blood samples obtained from 65 Chinese patients with PRNS were characterized using nonlinear mixed-effects modeling. The impacts of demographic features, biological characteristics and drug combination were evaluated. Model validation was assessed using the bootstrap method. A one-compartment model with first-order absorption and elimination was determined to be the most suitable model for TDM data in PRNS. The absorption rate constant (Ka) was set at 4.48 h⁻¹. The typical values of apparent oral clearance (CL/F) and apparent volume of distribution (V/F) in the final model were 5.46 l/h and 57.1 l, respectively. The inter-individual variability of CL/F and V/F were 22.2 and 0.2%, respectively. The PPK equation for TAC was: CL/F = 5.46 × exponential function (EXP)(0.0323 × age) × EXP(−0.359 × cystatin-C) × EXP(0.148 × daily dose of TAC). No significant effects of covariates on V/F were observed. In conclusion, the current study developed and validated the first TAC PPK model for patients with PRNS. The study also provided a summary of previous literature concerning other TAC PPK models in different pediatric diseases.

Population pharmacokinetics of tacrolimus in children with nephrotic syndrome

AIMS

Nephrotic syndrome (NS) is the most common clinical manifestation of glomerular disease in children. Currently, tacrolimus (TAC) is widely used in children with NS. However, pharmacokinetic data in children with nephrotic syndrome is limited. This study was intended to evaluate the population pharmacokinetics (PPK) of TAC in paediatric NS and to optimize dosing regimen.

METHODS

Blood samples from NS children treated with TAC were collected and the blood concentrations of TAC were detected using HPLC-MS/MS. A PPK model was developed using NONMEM software. Pharmacogenetic analysis was carried out in the CYP3A5 gene.

RESULTS

The data from 28 children were used for PPK analysis. A one-compartment model and first-order elimination were accorded with the TAC data in paediatric NS. A covariate analysis showed that body weight and CYP3A5 genotype significantly affected TAC pharmacokinetics. Monte Carlo simulation indicated that NS children with CYP3A5*3/*3 receiving 0.10 mg kg-1  dose-1 twice daily and NS children with CYP3A5*1 receiving 0.25 mg kg-1  dose-1 twice daily TAC could achieve the target concentrations of 5-10 ng ml-1 .

CONCLUSION

The PPK of TAC was estimated in children with NS and a CYP3A5 genotype-based dosing regimen was set up based on simulations.

Idiopathic nephrotic syndrome in children

The incidence of idiopathic nephrotic syndrome (NS) is 1·15-16·9 per 100 000 children, varying by ethnicity and region. The cause remains unknown but the pathogenesis of idiopathic NS is thought to involve immune dysregulation, systemic circulating factors, or inherited structural abnormalities of the podocyte. Genetic risk is more commonly described among children with steroid-resistant disease. The mainstay of therapy is prednisone for the vast majority of patients who are steroid responsive; however, the disease can run a frequently relapsing course, necessitating the need for alternative immunosuppressive agents. Infection and venous thromboembolism are the main complications of NS with also increased risk of acute kidney injury. Prognosis in terms of long-term kidney outcome overall is excellent for steroid-responsive disease, and steroid resistance is an important determinant of future risk of chronic or end-stage kidney disease.

Idiopathic nephrotic syndrome in South African children

BACKGROUND

Different histo-pathological types and treatment response patterns of Idiopathic nephrotic syndrome (INS) have been associated with differences in ethnicity and geographical location.

OBJECTIVE

To provide an update on the steroid response and renal histo-pathological pattern in children treated for INS.

METHOD

Medical records of children with INS treated at the Charlotte Maxeke Johannesburg Academic Hospital were reviewed.

RESULTS

Mean age was 5.3 years ± 2.8. The majority (68.1%) of the 163 children were of the black racial group. The highest rate of INS was seen in the 2-6 year age group (71.2%). The black racial group had the highest rate (42/111; 37.8%) of focal segmental glomerulosclerosis (FSGS), and the white race had the highest rate (9/14; 64.3%) of minimal change disease (MCD). Ninety four (57.7%) patients were steroid sensitive (SSNS) while 69 patients (42.3%) were steroid resistant (SRNS). Minimal change disease was the most common histo-pathological type seen in SSNS (60%), while FSGS was the most common observed in patients who had SRNS (65.2%).

CONCLUSION

There appears to be a higher rate of FSGS in all the racial groups, and also a higher rate of MCD in the black race group, when compared to previous reports.

Nephrotic syndrome in infants and children: pathophysiology and management

Nephrotic syndrome is defined by nephrotic-range proteinuria (≥40 mg/m²/hour or urine protein/creatinine ratio ≥200 mg/mL or 3+ protein on urine dipstick), hypoalbuminaemia (<25 g/L) and oedema. This review focuses on the classification, epidemiology, pathophysiology, management strategies and prognosis of idiopathic nephrotic syndrome of childhood, and includes a brief overview of the congenital forms.

Therapy of tacrolimus combined with corticosteroids in idiopathic membranous nephropathy

We evaluated the efficacy and safety of tacrolimus (TAC) combined with corticosteroids in treating patients with idiopathic membranous nephropathy (IMN). One hundred seventy-seven biopsy-proven IMN patients were recruited in this retrospective clinical study. Sixty patients received TAC (target blood concentration of 4–8 ng/mL) and 117 patients received daily cyclophosphamide (CYC, 100 mg) combined with prednisone. Remission rates at the end of the first, second and third month in the TAC group were significantly higher than that in the CYC group (1st: 35.0 vs 19.7%, P<0.05; 2nd: 56.7 vs 38.5%, P<0.05; 3rd: 76.7 vs 59.0%, P<0.05). In the first 3 months, daily urinary protein and serum albumin in the TAC group obtained a better improvement than that in the CYC group (P<0.05). At the end of the sixth and the twelfth month, the remission rates, daily urinary protein and serum albumin were all comparable between the two groups (P>0.05). No significant difference of relapse rate between the groups was found (16.3 vs 12.0%, P>0.05). Patients were more likely to develop glucose intolerance in the TAC group. The TAC regimen obtained more benefits in treating IMN patients, especially in the first 3 months, than the CYC regimen.

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.

Predictive risk factors of steroid dependent nephrotic syndrome in children

Background:

Development of steroid dependency is one of the difficult problems in the management of children with idiopathic nephrotic syndrome, leading to increased morbidity, complications and cost of treatment. Thus, predicting early in the disease course will be useful in counseling parents and may improve treatment strategy.

Objectives:

To determine the clinical characteristics that can predict the development of steroid dependency early in the initial episodes of steroid sensitive nephrotic syndrome (SSNS).

Patients and Methods:

The study included 52 children with SSNS. Their ages ranged from 3 to 16 years. Patients were divided into two groups. Group A consisted of 24 patients with steroid dependency or frequent relapses nephrotic syndrome and group B consisted of 28 patients with complete remission or recurrent nephrotic syndrome. Data obtained retrospectively from patients’ files.

Results:

Children who require a cumulative steroid dose equal or more than 140 mg/kg to maintain remission during the first 6 months of the disease are at high risk to require steroid sparing agents (SSA) for disease control, and who did not achieve remission by day 20 of the initial prednisone course became steroid dependent with 96% specificity but with low sensitivity (50%). All steroid dependent children in this study showed relapses associated significantly with upper respiratory tract infections.

Conclusions:

Cumulative steroid dose in the first 6 months of treatment and the need of more than 20 days to achieve initial remission can predict steroid dependency in children with nephrotic syndrome.

A Novel Biomarker Panel to Identify Steroid Resistance in Childhood Idiopathic Nephrotic Syndrome

Idiopathic nephrotic syndrome (NS) is the most common glomerular disorder of childhood. Response to initial treatment with corticosteroids is an indicator of prognosis, as resistant patients often present more progressive disease. In this cross-sectional pilot study, we set out to discover a panel of noninvasive biomarkers that could distinguish steroid-resistant nephrotic syndrome (SRNS) from steroid-sensitive nephrotic syndrome (SSNS). Information gleaned from such a panel could yield more individualized treatment plans and prevent unnecessary steroid exposure in patients unlikely to respond. Urine was collected from 50 pediatric patients diagnosed with idiopathic NS at Cincinnati Children's Hospital Medical Center. Isobaric tags for relative and absolute quantitation (iTRAQ) was used to discover 13 proteins that were differentially expressed in SSNS vs SRNS in a small 5 × 5 discovery cohort. Suitable assays were found for 9 of the 13 markers identified by iTRAQ and were used in a 25 SRNS × 25 SSNS validation cohort. Vitamin D-binding protein (VDBP), alpha-1 acid glycoprotein 1 (AGP1), alpha-1 acid glycoprotein 2 (AGP2), alpha-1-B glycoprotein (A1BG), fetuin-A, prealbumin, thyroxine-binding globulin and hemopexin, and alpha-2 macroglobulin were measured and combined with urine neutrophil gelatinase-associated lipocalin (NGAL), which had been previously shown to distinguish patients with SRNS. Urinary VDBP, prealbumin, NGAL, fetuin-A, and AGP2 were found to be significantly elevated in SRNS using univariate analysis, with area under the receiver operating characteristic curves (AUCs) ranging from 0.65 to 0.81. Multivariate analysis revealed a panel of all 10 markers that yielded an AUC of 0.92 for identification of SRNS. A subset of 5 markers (including VDBP, NGAL, fetuin-A, prealbumin, and AGP2) showed significant associations with SRNS and yielded an AUC of 0.85.

Tacrolimus Monotherapy after Intravenous Methylprednisolone in Adults with Minimal Change Nephrotic Syndrome

Glucocorticoid treatment is the first choice therapy for adults with minimal change nephrotic syndrome; however, this therapy associates with many adverse effects. Tacrolimus may be an alternative to conventional glucocorticoid therapy. To investigate this possibility, we conducted a prospective, randomized, controlled trial (WHO International Clinical Trials Registry Platform: ChiCTR-TRC-11001454) in eight renal units across China. We randomized enrolled patients with adult-onset minimal change nephrotic syndrome (n=119) to receive glucocorticoid therapy or tacrolimus after intravenous methylprednisolone (0.8 mg/kg per day) for 10 days. Patients received a conventional glucocorticoid regimen or tacrolimus monotherapy, starting with 0.05 mg/kg per day (target trough whole-blood level of 4-8 ng/ml) for 16-20 weeks and subsequently tapering over approximately 18 weeks. Remission occurred in 51 of 53 (96.2%; all complete remission) glucocorticoid-treated patients and 55 of 56 (98.3%; 52 complete and three partial remission) tacrolimus-treated patients (P=0.61 for remission; P=0.68 for complete remission). The groups had similar mean time to remission (P=0.55). Relapse occurred in 49.0% and 45.5% of the glucocorticoid- and tacrolimus-treated patients, respectively (P=0.71), with similar time to relapse (P=0.86). Seven (13.7%) glucocorticoid-treated and four (7.3%) tacrolimus-treated patients suffered frequent relapse (P=0.28); five glucocorticoid-treated and two tacrolimus-treated patients became drug dependent (P=0.26). Adverse events occurred more frequently in the glucocorticoid group (128 versus 81 in the tacrolimus group). Seven adverse events in the glucocorticoid group and two adverse events in the tacrolimus group were serious. Consequently, tacrolimus monotherapy after short-term intravenous methylprednisolone is noninferior to conventional glucocorticoid treatment for adult-onset minimal change nephrotic syndrome in this cohort.

Tacrolimus combined with low-dose corticosteroids is an effective and safe therapeutic option for refractory IgA nephropathy

Tacrolimus (TAC) has been shown to improve remission from proteinuria in patients with refractory IgA nephropathy (IgAN); however, the efficacy and safety of TAC in such patients have not been fully explored. Therefore, the present study was conducted to evaluate the tolerance to and efficacy of TAC combined with low-dose corticosteroids in patients with refractory IgAN. This was a single-center retrospective study. A total of 28 patients with refractory IgAN were randomly included and received TAC plus corticosteroid; 26 patients received TAC and prednisone, and 2 patients received TAC and methylprednisolone. In addition, all patients were treated with an angiotensin inhibitor. Total urinary protein excretion, serum albumin, blood glucose, complete remission (CR), partial remission (PR), cholesterol, low-density lipoprotein (LDL), serum creatinine (Scr) and estimated GFR (eGFR) were tested at baseline and at 3, 6 and 12 months after the initiation of treatment in all patients. The primary endpoints were CR and PR. Secondary endpoints included changes of Scr, eGFR, clinical data and adverse events. After 12 months, CR was achieved in 40.1% of patients and PR in 43.4%, yielding a total response rate of 83.5%, and the total urinary protein excretion, serum albumin, cholesterol and LDL results were improved significantly compared with those at baseline. Proteinuria and serum albumin results were significantly improved by month 3 of treatment. Two patients relapsed during months 3-6 of follow-up. At the 12-month follow-up, renal function was improved compared with the baseline level as evidenced by eGFR and Scr, respectively. The blood glucose level was stable. One case of pneumococcal pneumonia developed in a patient treated with TAC plus low-dose methylprednisolone and one case of upper gastrointestinal hemorrhage was found in a patient treated with TAC plus low-dose prednisone; both cases completely recovered after treatment. In conclusion, TAC combined with low-dose corticosteroids may be an effective and safe therapeutic option for the treatment of refractory IgAN. However, given the small number of patients in this study, further prospective randomized controlled trials are required with a larger sample of participants and longer follow-up period.

Urinary Vitamin D-Binding Protein as a Biomarker of Steroid-Resistant Nephrotic Syndrome

BACKGROUND

Idiopathic nephrotic syndrome (NS) is one of the most common glomerular disorders of childhood and is associated with increased urinary vitamin D-binding protein (uVDBP) excretion. We tested the hypothesis that uVDBP represents a biomarker to differentiate steroid-resistant nephrotic syndrome (SRNS) from the more benign forms of steroid-sensitive nephrotic syndrome (SSNS).

METHODS

This cross-sectional study included children with SRNS (n = 24), SSNS (n = 28), and normal controls (n = 5). Urine and clinical data were collected from patients. Measurements of uVDBP were performed with a commercially available ELISA kit and normalized to urine creatinine.

RESULTS

Concentrations of uVDBP were significantly higher (P < 0.001) in patients with SRNS (13,659 ng/mL, interquartile range [IQR] 477–22,979) than in patients with SSNS (94 ng/mL, IQR 53–202) and normal controls (23 ng/mL, IQR 22–99, P = 0.002). Significance did not change when the results were corrected for urine creatinine. uVDBP was significantly negatively correlated with estimated glomerular filtration rate (eGFR; R = −0.76, P = 0.03). However, uVDBP was still markedly elevated in patients with SRNS with eGFR >100 mL/minute/1.73 m². There was a positive correlation between microalbuminuria (MALB/Cr) and uVDBP (R = 0.67, P < 0.001). However, uVDBP displayed a much higher discriminatory ability for distinguishing SRNS than MALB/Cr (area under the curve = 0.92 vs 0.67, respectively). An uVDBP cutoff of 362 ng/mL yielded the optimal sensitivity (80%) and specificity (83%) to distinguish SRNS from SSNS.

CONCLUSIONS

In this preliminary study, uVDBP represents a noninvasive biomarker that could distinguish SRNS from the more benign SSNS with high discriminatory power.

Response to cyclosporine in steroid-resistant nephrotic syndrome: discontinuation is possible

BACKGROUND

Steroid-resistant nephrotic syndrome (SRNS) is still regarded as a serious disease although treatment with cyclosporine (CSA) has improved outcome. However, the duration of treatment in responders is unclear, and treatment of patients with genetic causes is a matter of debate.

METHODS

Thirty-six patients with SRNS were studied retrospectively. Median age at presentation was 3.2 (range, 0.06-15.0) and median follow-up 15.5 years (range, 1.8-27.7), respectively; 23 (64%) had focal segmental glomerulosclerosis (FSGS) on biopsy. In 33/36 patients (92%), genetic testing was performed for at least three most common genes known to be mutated in SRNS.

RESULTS

Nineteen patients (53%), especially those with minimal change nephrotic syndrome (MCNS) at initial biopsy (p < 0.002), entered complete remission with CSA monotherapy, including one patient with compound heterozygous NPHS1 and dominant ACTN4 mutation, respectively. Ten patients entered partial remission (28%, all FSGS), including two with NPHS2 mutations. Seven patients (six FSGS, one MCNS) did not respond to treatment. In 15 of 19 responders to CSA, treatment was stopped after a median of 3.1 years (range, 0.5-14) and no further relapses occurred in 11/15 (73%) patients with median follow-up of 9.7 years.

CONCLUSIONS

CSA monotherapy is effective in SRNS. Discontinuation of CSA is possible in many patients with complete remission.

Spectrum of steroid-resistant and congenital nephrotic syndrome in children: the PodoNet registry cohort

BACKGROUND AND OBJECTIVES

Steroid-resistant nephrotic syndrome is a rare kidney disease involving either immune-mediated or genetic alterations of podocyte structure and function. The rare nature, heterogeneity, and slow evolution of the disorder are major obstacles to systematic genotype-phenotype, intervention, and outcome studies, hampering the development of evidence-based diagnostic and therapeutic concepts. To overcome these limitations, the PodoNet Consortium has created an international registry for congenital nephrotic syndrome and childhood-onset steroid-resistant nephrotic syndrome.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Since August of 2009, clinical, biochemical, genetic, and histopathologic information was collected both retrospectively and prospectively from 1655 patients with childhood-onset steroid-resistant nephrotic syndrome, congenital nephrotic syndrome, or persistent subnephrotic proteinuria of likely genetic origin at 67 centers in 21 countries through an online portal.

RESULTS

Steroid-resistant nephrotic syndrome manifested in the first 5 years of life in 64% of the patients. Congenital nephrotic syndrome accounted for 6% of all patients. Extrarenal abnormalities were reported in 17% of patients. The most common histopathologic diagnoses were FSGS (56%), minimal change nephropathy (21%), and mesangioproliferative GN (12%). Mutation screening was performed in 1174 patients, and a genetic disease cause was identified in 23.6% of the screened patients. Among 14 genes with reported mutations, abnormalities in NPHS2 (n=138), WT1 (n=48), and NPHS1 (n=41) were most commonly identified. The proportion of patients with a genetic disease cause decreased with increasing manifestation age: from 66% in congenital nephrotic syndrome to 15%-16% in schoolchildren and adolescents. Among various intensified immunosuppressive therapy protocols, calcineurin inhibitors and rituximab yielded consistently high response rates, with 40%-45% of patients achieving complete remission. Confirmation of a genetic diagnosis but not the histopathologic disease type was strongly predictive of intensified immunosuppressive therapy responsiveness. Post-transplant disease recurrence was noted in 25.8% of patients without compared with 4.5% (n=4) of patients with a genetic diagnosis.

CONCLUSIONS

The PodoNet cohort may serve as a source of reference for future clinical and genetic research in this rare but significant kidney disease.

Long-Term Outcomes in Children with Steroid-Resistant Nephrotic Syndrome Treated with Calcineurin Inhibitors

BACKGROUND

Steroid-resistant nephrotic syndrome (SRNS) is an important cause of chronic kidney disease (CKD) in children that often progresses to end-stage renal disease (ESRD). Calcineurin inhibitors (CNIs) have been shown to be effective in inducing short-term remission in some patients with SRNS. However, there are little data examining their long-term impact on ESRD progression rates.

METHODS

We performed a retrospective chart review of all patients treated for SRNS with CNIs at our institution from 1995 to 2013. Data collected including demographics, initial response to medical therapy, number of relapses, progression to ESRD, and treatment complications.

RESULTS

A total of 16 patients met inclusion criteria with a mean follow-up of 6.6 years (range 0.6-17.6 years). Histopathological diagnoses were focal segmental glomerulosclerosis (8), mesangial proliferative glomerulonephritis (4), IgM nephropathy (3), and minimal change disease (1). Three patients (18.8%) were unresponsive to CNIs while the remaining 13 (81.2%) achieved remission with CNI therapy. Six patients (37.5%) progressed to ESRD during the study period, three of whom did so after initially responding to CNI therapy. Renal survival rates were 87, 71, and 57% at 2, 5, and 10 years, respectively. Non-Caucasian ethnicity was associated with progression to ESRD. Finally, a higher number of acute kidney injury (AKI) episodes were associated with a lower final estimated glomerular filtration rate.

DISCUSSION

Despite the majority of SRNS patients initially responding to CNI therapy, a significant percentage still progressed to ESRD despite achieving short-term remission. Recurrent episodes of AKI may be associated with progression of CKD in patients with SRNS.

A new 'tac' for childhood nephrotic syndrome

Calcineurin inhibitors (CNIs) are frequent first-line agents in children with steroid-resistant nephrotic syndrome (SRNS). However, limited randomized controlled trial (RCT) data are available comparing CNIs with alternative therapies. Gulati and colleagues report their experience with tacrolimus versus cyclophosphamide in childhood SRNS. Their results establish clear superiority of tacrolimus over cyclophosphamide and give further proof that RCTs in childhood SRNS are both feasible and vital for improving the standard of care.

Efficacy of tacrolimus in the treatment of children with focal segmental glomerulosclerosis

BACKGROUND

Focal segmental glomerulosclerosis (FSGS) is the most common glomerular condition leading to end-stage renal disease (ESRD) and the third most common cause of ESRD in pediatric patients.

METHODS

This is a retrospective study consisting of 22 pediatric patients with FSGS and heavy proteinuria. After demonstrating steroids resistance, the patients were treated with tacrolimus, targeting a trough level 5-8 ng/mL. The primary outcome is the induction of remission with tacrolimus.

RESULTS

Thirteen patients (59%) achieved remission (complete in 31.8% and partial in 27.2%) and 12 patients showed stable or improved renal function over an average follow-up of 2.9 years (range: 0.5-7 years). There was no significant difference in response rate between African American and Caucasian patients. None of the patients had significant side-effect to tacrolimus and none of the repeat biopsies showed an increase in interstitial fibrosis compared to baseline. The best renal outcome was for patients who achieved complete remission. Partially responsive patients had improved renal function compared with resistant patients.

CONCLUSION

Tacrolimus is a viable option in the treatment of children with idiopathic steroid resistant FSGS.

Treatment of FSGS in Children

Focal segmental glomerulosclerosis (FSGS) is a pathologic condition that represents many disease entities. The goals of therapy are to cure the disease. When this is not possible, the secondary goals are to reduce proteinuria to avoid the complications of nephrotic syndrome and to delay progression of kidney disease. Proteinuria remission is one of the most important independent predictors of kidney survival. Children with FSGS who do not achieve partial or complete remission have a 50% risk of progression to ESRD within 5 years whereas those who enter complete remission have a 5-year kidney survival rate of 90%. Treatment of idiopathic FSGS commonly involves immune-based and nonimmunologic therapy options. This manuscript will review the current state of FSGS therapy for children.

Second-line immunosuppressive treatment of childhood nephrotic syndrome: a single-center experience

Objective

Most cases of idiopathic nephrotic syndrome in childhood are responsive to corticosteroids. However, there is a small group of children that demonstrate steroid resistance (steroid-resistant nephrotic syndrome; SRNS), steroid dependence, or that frequently relapse (frequent-relapse steroid-sensitive nephrotic syndrome; FR-SSNS) which are more clinically difficult to treat. Therefore, second-line immunosuppressants, such as alkylating agents, calcineurin inhibitors, antimetabolites and, more recently, rituximab, have been used with varying success. The objective was to evaluate the response rates of various second-line therapies in the treatment of childhood nephrotic syndrome.

Study Design

A retrospective chart review of pediatric subjects with idiopathic nephrotic syndrome was conducted at a single tertiary care center (2007-2012). Drug responses were classified as complete response, partial response, and no response.

Results

Of the 188 charts reviewed, 121 children were classified as SSNS and 67 children as SRNS; 58% were classified as FR-SSNS. Sixty-five subjects were diagnosed with focal segmental glomerulosclerosis via biopsy. Follow-up ranged from 6 months to 21 years. The combined rate of complete and partial response for mycophenolate mofetil (MMF) was 65% (33/51) in SSNS and 67% (6/9) in SRNS. For tacrolimus, the response rate was 96% (22/23) for SSNS and 77% (17/22) for SRNS. Eighty-three percent (5/6) of SSNS subjects treated with rituximab went into complete remission; 60% relapsed after B-cell repletion. Eight refractory subjects were treated with combined MMF/tacrolimus/corticosteroid therapy with a 75% response rate.

Conclusion

Our experience demonstrates that older medications can be replaced with newer ones such as MMF, tacrolimus, and rituximab with good outcomes and better side effect profiles. The treatment of refractory cases with combination therapy is promising.

Urinary low-molecular-weight protein excretion in pediatric idiopathic nephrotic syndrome

BACKGROUND

Minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) are the most common causes of idiopathic nephrotic syndrome (INS). We have evaluated the reliability of urinary neutrophil-gelatinase-associated lipocalin (uNGAL), urinary alpha1-microglobulin (uα1M) and urinary N-acetyl-beta-D-glucosaminidase (uβNAG) as markers for differentiating MCD from FSGS. We have also evaluated whether these proteins are associated to INS relapses or to glomerular filtration rate (GFR).

METHODS

The patient cohort comprised 35 children with MCD and nine with FSGS; 19 healthy age-matched children were included in the study as controls. Of the 35 patients, 28 were in remission (21 MCD, 7 FSGS) and 16 were in relapse (14 MCD, 2 FSGS). The prognostic accuracies of these proteins were assessed by receiver operating characteristic (ROC) curve analyses.

RESULTS

The level of uNGAL, indexed or not to urinary creatinine (uCreat), was significantly different between children with INS and healthy children (p = 0.02), between healthy children and those with FSGS (p = 0.007) and between children with MCD and those with FSGS (p = 0.01). It was not significantly correlated to proteinuria or GFR levels. The ROC curve analysis showed that a cut-off value of 17 ng/mg for the uNGAL/uCreat ratio could be used to distinguish MCD from FSGS with a sensitivity of 0.77 and specificity of 0.78. uβNAG was not significantly different in patients with MCD and those with FSGS (p = 0.86). Only uα1M, indexed or not to uCreat, was significantly (p < 0.001) higher for patients in relapse compared to those in remission.

CONCLUSIONS

Our results indicate that in our patient cohort uNGAL was a reliable biomarker for differentiating MCD from FSGS independently of proteinuria or GFR levels.

Tacrolimus as rescue therapy for adult-onset refractory minimal change nephrotic syndrome with reversible acute renal failure

BACKGROUND

Some adult patients with minimal change nephrotic syndrome (MCNS) who are refractory to steroid treatment or combination with immunosuppressive drug developed reversible acute renal failure (ARF) due to persistent severe hypoalbuminemia and proteinuria. It is a challenge to find rescue therapies that are effective and safe in treating such difficult patients.

METHODS

In this prospective observational study, 13 patients with adult-onset MCNS, all unresponsive to treatment with a steroid or a steroid with other immunosuppressive drugs, were studied from January 2005 to February 2009. All patients developed ARF before enrollment. Oral tacrolimus (TAC) was started at 1 mg/day (target trough levels of 3-6 ng/mL) before serum creatinine (SCr) decreased to ≤133 μmol/L, and then increased doses were given (target trough level of 5-10 ng/mL) when SCr decreased to ≤133 μmol/L. Primary outcome variables were remission, and recovery from ARF. Secondary outcome variables were time to recovery from ARF, time to remission, relapse rate, changes in SCr and estimated glomerular filtration rate (eGFR).

RESULTS

One patient discontinued TAC due to deterioration of ARF, and 12 patients recovered from ARF. The mean time to recovery from ARF was 15.8 ± 4.4 days. Nine patients (69.2%) experienced complete remission (CR) and two patients (15.4%) experienced partial remission (PR). The mean time to PR and CR was 4.8 ± 2.7 and 9.4 ± 2.3 weeks, respectively. After a mean follow-up of 69.6 months, 36.4% (4/11) of patients who had remission experienced relapses. One patient who was resistant to TAC therapy had a doubling of serum creatinine concentration during follow-up.

CONCLUSIONS

TAC may be a suitable therapeutic option for treatment of adult-onset refractory MCNS with reversible ARF.

Effect of prolonged tacrolimus treatment in idiopathic membranous nephropathy with nephrotic syndrome

OBJECTIVE

Tacrolimus has been used for idiopathic membranous nephropathy (IMN) therapy, but most patients who achieved remission showed a high relapse rate when tacrolimus was withdrawn after 6-12 months of therapy. We proposed that a prolonged therapeutic course should help reduce the relapse rate.

METHODS

A total of 42 patients with nephrotic syndrome caused by IMN were randomly divided into short-term (n = 20) and long-term (n = 22) groups. All patients received initial treatment with tacrolimus and prednisone for 6 months, and afterward only the long-term patient group was tapered with low-dose tacrolimus until 24 months.

RESULTS

Over 85% of the patients achieved proteinuria reduction, serum albumin improvement and serum lipid recovery; the probability of remission in both groups was over 80% at 6 months. The remission rate was steady at over 80% after 12 and 24 months in the long-term group, but only 50 and 45%, respectively, in the short-term group. Nine patients (45%) relapsed in the short-term group after tacrolimus withdrawal, while not a single patient suffered recurrence in the long-term group. The concentration of tacrolimus remained similar between the two groups at 5-8 ng/ml during the initial 6 months, and was significantly decreased at 12 months compared to 6 months (p < 0.05), along with reduction of oral administration in the long-term group.

CONCLUSION

Combined therapy of tacrolimus with prednisone can relieve IMN significantly; prolonged tacrolimus treatment at a low blood concentration can alleviate the illness persistently, with a low recurrence rate and gratifying safety.

Prospective 5-year follow-up of cyclosporine treatment in children with steroid-resistant nephrosis

BACKGROUND

Cyclosporine has improved remission rates in children with steroid-resistant nephrotic syndrome (SRNS). However, little prospective long-term follow-up data is available.

METHODS

We prospectively followed and analyzed 5-year outcomes of all 35 patients enrolled in our previous prospective multicenter trial with cyclosporine and steroids in children with SRNS. At enrollment, 23 cases were classified as minimal change (MC), five as diffuse mesangial proliferation (DMP), and seven as focal segmental glomerulosclerosis (FSGS).

RESULTS

Renal survival at 5 years (median 7.7 years) was 94.3 %. Patient status was complete remission (CR) in 31 (88.6 %) (MC/DMP, 25; FSGS, 6); partial remission in one (FSGS); and non-remission in three (MC/DMP), including chronic kidney disease and end-stage kidney disease in one each. Among 31 patients with CR, 22 (71.0 %) were receiving treatment with immunosuppressants at 5 years, including cyclosporine in 19, and seven of these 22 continued to show frequent relapse. Response to cyclosporine at 4 months predicted 5-year outcome in 31 of 35 patients.

CONCLUSIONS

Although SRNS treatment with cyclosporine provides high renal survival and remission rates, many children require ongoing immunosuppression. Management has advanced from the prevention of end-stage kidney disease to the long-term maintenance of remission and management of relapse after induction therapy.

Treatment of tacrolimus or cyclosporine A in children with idiopathic nephrotic syndrome

BACKGROUND

Cyclosporine A (CsA) and tacrolimus (TAC) are often alternative treatment choices for patients with nephrotic syndrome.

METHODS

In this prospective study, the efficacy and safety of CsA and TAC in inducing and maintaining remission in 74 children with idiopathic nephrotic syndrome (INS) were evaluated.

RESULTS

In terms of short-term efficacy, TAC was more effective than CsA in children with steroid-resistant nephrotic syndrome (χ(2) = 13.75, P = 0.001), although no significant difference in number of episodes of relapse were found in patients with complete remission between the two treatment groups (first year: χ(2) = 0.261, P = 0.88; second year: χ(2) = 2.685, P = 0.26). In patients with frequently relapsing or steroid-dependent nephrotic syndrome, no significant difference in short-term remission (χ(2) = 1.908, P = 0.39) or in relapse frequency during follow-up (within first year: χ(2) = 1.046, P = 0.59; within second year: χ(2) = 0.587, P = 0.75) were found between the two groups. There was a difference in the rate of adverse effects between the two treatment groups [nephrotoxicity: 4/24 (CsA) vs .0/50 (TAC), P = 0.002; hirsutism: 8/24 (CsA) vs. 0/50 (TAC), P < 0.001].

CONCLUSIONS

In our pediatric patient cohort, the treatment of steroid-resistant nephrotic syndrome with tacrolimus was associated with higher efficacy and lower renal toxicity in comparison to CsA, although no favorable outcome in relapse rate during long-term follow-up was seen. On the other hand, tacrolimus was not always the better choice to replace CsA in the treatment of severe frequently relapsing or steroid-dependent nephrotic syndrome.

Treatment with tacrolimus and prednisolone is preferable to intravenous cyclophosphamide as the initial therapy for children with steroid-resistant nephrotic syndrome

There are limited data on the relative efficacy and safety of calcineurin inhibitors and alkylating agents for idiopathic steroid-resistant nephrotic syndrome in children. To clarify this, we compared tacrolimus and intravenous cyclophosphamide therapy in a multicenter, randomized, controlled trial of 131 consecutive pediatric patients with minimal change disease, focal segmental glomerulosclerosis, or mesangioproliferative glomerulonephritis, stratified for initial or late steroid resistance. Patients were randomized to receive tacrolimus for 12 months or 6-monthly infusions of intravenous cyclophosphamide with both arms receiving equal amounts of alternate-day prednisolone. The primary outcome of complete or partial remission at 6 months, based on spot urine protein to creatinine ratios, was significantly higher in children receiving tacrolimus compared to cyclophosphamide (hazard ratio 2.64). Complete remission was significantly higher with tacrolimus (52.4%) than with cyclophosphamide (14.8%). The secondary outcome of sustained remission or steroid-sensitive relapse of nephrotic syndrome at 12 months was significantly higher with tacrolimus than cyclophosphamide. Treatment withdrawal was higher with cyclophosphamide, chiefly due to systemic infections. Compared to cyclophosphamide, 3 patients required treatment with tacrolimus to achieve 1 additional remission. Thus, tacrolimus and prednisolone are effective, safe, and preferable to cyclophosphamide as the initial therapy for patients with steroid-resistant nephrotic syndrome.

NGAL distinguishes steroid sensitivity in idiopathic nephrotic syndrome

BACKGROUND

Idiopathic nephrotic syndrome (NS) is the most common glomerular disorder of childhood. Invasive biopsy remains the diagnostic method of choice for NS. Prognosis correlates with steroid responsiveness, from sensitive (SSNS) to resistant (SRNS). Neutrophil gelatinase-associated lipocalin (NGAL) has been demonstrated to be a powerful risk marker of chronic kidney disease progression. We set out to determine if urine NGAL can distinguish between patients with SRNS, SSNS, and healthy controls.

METHODS

Urine and clinical data were collected from patients at Cincinnati Children's Hospital who were recently diagnosed with active nephrotic syndrome as well as healthy controls. Participants included SRNS (n = 15), SSNS (n = 14), and healthy controls (n = 10). Urinary NGAL was measured by ELISA and normalized to creatinine.

RESULTS

Median NGAL was significantly (p < 0.001) higher in SRNS (172.3 ng/ml, IQR 18.8-789) than both SSNS (6.3 ng/ml, IQR 4.9-9.9) and healthy controls (6.5 ng/ml, IQR 4.2-9.1). The area under the curve (AUC) for NGAL to distinguish SRNS from SSNS was 0.91 (p < 0.0001). NGAL levels demonstrated a significant negative correlation with glomerular filtration rate (r = -0.5, p < 0.001). Results did not change with NGAL corrected for urine creatinine and were independent of the degree of proteinuria.

CONCLUSIONS

NGAL levels differentiate SSNS from SRNS and correlate with disease severity in SRNS.

Tacrolimus improves the proteinuria remission in patients with refractory IgA nephropathy

BACKGROUND

Tacrolimus has been reported to be effective in refractory nephrotic syndrome, such as focal segmental glomerulosclerosis and membranous nephropathy. Some IgA nephropathy (IgAN) patients with massive proteinuria showed resistance to steroids and/or cytotoxic immunosuppressants based on the supportive therapy with renin- angiotensin system blockade. The efficacy and safety of tacrolimus in such refractory IgAN patients are extremely ambiguous, and the mechanism of tacrolimus improving proteinuria remission needs to be investigated.

METHODS

14 refractory IgAN patients were enrolled. The patients received tacrolimus (0.05-0.1 mg/kg/day) and prednisone (0.5 mg/kg/day) for at least 6 months. Synaptopodin and calcineurin expression were detected in renal tissues of patients who received re-biopsy. A puromycin aminonucleoside (PAN)-induced human podocyte injury model was applied to investigate the possible role of tacrolimus in proteinuria remission.

RESULTS

Of the 14 patients enrolled, 3 were withdrawn because serum creatinine increased over 30% baseline. In 11 patients treated with tacrolimus over 6 months, 9 showed complete or partial remission and 7 achieved remission within 1 month. In renal tissues, the expression of calcineurin increased while synaptopodin decreased and recovered partially after tacrolimus therapy. In an in vitro study, F-actin disrupted in human podocytes after stimulation of PAN, while calcineurin increased and synaptopodin decreased. After co-treatment with tacrolimus the reorganization of F-actin and the expression of calcineurin and synaptopodin recovered.

CONCLUSIONS

Tacrolimus showed a rapid proteinuria remission in refractory IgAN patients. The possible mechanism of tacrolimus to proteinuria remission might be podocyte cytoskeleton stabilization through inhibition of calcineurin expression.

Novel multidrug therapy for children with cyclosporine-resistant or -intolerant nephrotic syndrome

An effective treatment for children with refractory nephrotic syndrome (NS), especially in those with cyclosporine (CsA)-resistant or CsA-intolerant NS, has yet to be established. Recently, the efficacy of multidrug therapy consisting of tacrolimus (Tac), mycophenolate mofetil (MMF) in combination with prednisolone (PDN) in adult patients with refractory NS has been reported. We successfully treated 14 consecutive children with refractory CsA-resistant or CsA-intolerant NS using combination therapy consisting of relatively low-dose Tac, mizoribine (MZR), which has a mechanism of action very similar to that of MMF, and PDN. There were no serious clinical toxicities. Of the 14 children, 9 with a mean age of 13.0 years had steroid-dependent NS (SDNS) and 5 with a mean age of 9.6 years had steroid-resistant NS (SRNS). All SDNS patients had minimal change disease (MCD), 4 with SRNS had focal segmental glomerulosclerosis (FSGS), and the remaining child had MCD on renal biopsy. All patients were in a prospective cohort, but were evaluated retrospectively. The mean follow-up from the initiation of multidrug therapy was 18.4 months in SDNS and 18.6 months in SRNS patients. At the last observation point, the calculated relapse rate and minimum dose of PDN required for maintenance of clinical remission after the start of multidrug therapy were significantly decreased compared with those prior to this therapy, while on CsA, in SDNS patients (0.4 ± 0.5 times/year vs 2.9 ± 1.5 times/year, P = 0.0077, and 0.3 ± 0.2 mg/kg on alternate days vs 0.5 ± 0.2 mg/kg on alternate days, P = 0.0184 respectively). All SDNS and two SRNS patients (40%) achieved complete remission, allowing further decreases in the minimal doses of PDN required for maintenance of clinical remission in most our patients. However, one patient with FSGS remained refractory to multidrug therapy and subsequently developed end-stage renal disease. These clinical observations, although preliminary and involving a small number of patients, suggest that multidrug therapy consisting of relatively low-dose Tac, MZR, and PDN might be effective and safe for treating children with refractory CsA-resistant or CsA-intolerant NS. However, further studies involving larger numbers of patients are needed.

New therapies in steroid-sensitive and steroid-resistant idiopathic nephrotic syndrome

Although many children with idiopathic nephrotic syndrome (INS) respond initially to steroid therapy, repeated courses for patients with relapses often cause significant steroid toxicity. Patients with frequent relapses who develop steroid dependency thus require alternative treatment. The first such options have been considered to be cyclophosphamide or levamisole, although the latter is no longer available in many countries. There is also an increasing body of data indicating that mycophenolic acid (MPA) may be an alternative for these patients. Calcineurin inhibitors (cyclosporine A or tacrolimus) are usually effective and often used after cytotoxic treatment, but long-term treatment with these agents is necessary, raising concerns of a possible accumulation of side effects. Some patients show a tendency to relapse even on such maintenance regimens, and some even have a refractory course that creates a medical dilemma. For this situation, recent data indicate that monoclonal antibodies directed to B-cells (e.g. rituximab) may have some effect and that such drugs may also prove to be a therapeutic option in less complicated cases. Patients that do not respond to steroid treatment need genetic testing and a renal biopsy since focal segmental glomerulosclerosis (FSGS) may be present. Treatment options include pulse methylprednisolone, often in addition to calcineurin inhibitors, mainly in the form of cyclosporine, but tacrolimus has also come into recent favor. Some studies have found cytotoxic treatment, especially intravenous cyclophosphamide, to be effective in steroid resistant nephrotic syndrome, but it seems to be inferior to calcineurin inhibitors. MPA and rituximab have also been used in children with primary FSGS, but the response seems to be inferior to that in patients with steroid sensitive nephrotic syndrome. Taken together, INS in both steroid-sensitive and steroid-resistant patients is a potentially complicated disorder, and despite a wide arsenal of immunological interventions, some patients have a treatment refractory course. Prospective studies or at least standardized treatment for complicated cases is urgently needed.

A phase 1, single-dose study of fresolimumab, an anti-TGF-β antibody, in treatment-resistant primary focal segmental glomerulosclerosis

Primary focal segmental glomerulosclerosis (FSGS) is a disease with poor prognosis and high unmet therapeutic need. Here, we evaluated the safety and pharmacokinetics of single-dose infusions of fresolimumab, a human monoclonal antibody that inactivates all forms of transforming growth factor-β (TGF-β), in a phase I open-label, dose-ranging study. Patients with biopsy-confirmed, treatment-resistant, primary FSGS with a minimum estimated glomerular filtration rate (eGFR) of 25  ml/min per 1.73  m(2), and a urine protein to creatinine ratio over 1.8  mg/mg were eligible. All 16 patients completed the study in which each received one of four single-dose levels of fresolimumab (up to 4  mg/kg) and was followed for 112 days. Fresolimumab was well tolerated with pustular rash the only adverse event in two patients. One patient was diagnosed with a histologically confirmed primitive neuroectodermal tumor 2 years after fresolimumab treatment. Consistent with treatment-resistant FSGS, there was a slight decline in eGFR (median decline baseline to final of 5.85 ml/min per 1.73  m(2)). Proteinuria fluctuated during the study with the median decline from baseline to final in urine protein to creatinine ratio of 1.2  mg/mg with all three Black patients having a mean decline of 3.6  mg/mg. The half-life of fresolimumab was ∼14 days, and the mean dose-normalized Cmax and area under the curve were independent of dose. Thus, single-dose fresolimumab was well tolerated in patients with primary resistant FSGS. Additional evaluation in a larger dose-ranging study is necessary.

Discovery and initial validation of α 1-B glycoprotein fragmentation as a differential urinary biomarker in pediatric steroid-resistant nephrotic syndrome

PURPOSE

In this cross-sectional pilot study we set out to discover a non-invasive biomarker that could distinguish steroid-resistant nephrotic syndrome (SRNS) from steroid-sensitive nephrotic syndrome (SSNS).

EXPERIMENTAL DESIGN

Urine and clinical data were collected from patients with idiopathic nephrotic syndrome and healthy controls. Using SELDI-TOF-MS, we identified an 11-fold upregulated 13.8 kDa fragment of α 1-B glycoprotein (A1BG) in urine in SRNS. To validate our findings, A1BG was detected by Western blot. Creatinine was measured and transformed to glomerular filtration rate (GFR) by the new Schwartz formula and classified to chronic kidney disease (CKD) stage. p-Values were determined by unpaired t-test and Mann-Whitney rank sum test. Microalbumin was also measured to determine albumin/creatinine ratios.

RESULTS

The 13.8 kDa A1BG was present in 7 of 19 patients with SRNS; but absent in all SSNS (n=15) and controls (n=10). The A1BG(+) patients had lower GFR than A1BG(-) patients (p<0.009) and tended to have higher CKD stage.

CONCLUSION AND CLINICAL RELEVANCE

The 13.8 kDa A1BG fragment had a high discriminatory power for steroid resistance in pediatric nephrotic syndrome, but is only present in a subset of patients. Additional longitudinal studies are required to determine the usefulness of this biomarker as a non-invasive predictive marker of therapeutic response.

Renal interstitial fibrosis in children treated with FK506 for nephrotic syndrome

BACKGROUND

Steroid-dependent, steroid-resistant or frequently relapsing nephrotic syndrome carries a poor prognosis, including progression to renal failure. There are a number of studies confirming the efficacy of FK506 in steroid-resistant or steroid-dependent nephrotic syndrome. Although the use of this medication is becoming more common, we know very little about the potential nephrotoxicity when used in nephrotic syndrome.

METHOD

We retrospectively reviewed the characteristics and biopsy findings of 11 children with steroid-dependent or frequently relapsing nephrotic syndrome treated with FK506. Two sequential biopsies were evaluated for the change in interstitial fibrosis, measured by a quantitative stereological method, and the change in arteriolar hyaline thickening, tubular atrophy and interstitial fibrosis, graded according to Banff criteria.

RESULTS

There was an increase in interstitial fibrosis (P = 0.005), with a median absolute change in the per cent volume density between initial and follow-up biopsies of 1.8% [interquartile range (IQR) 3.9%]. Median percentage change in volume density of interstitial fibrosis, relative to volume density of interstitial fibrosis prior to initiating FK506, was 93% (IQR 138%). Banff scores for interstitial fibrosis and tubular atrophy also increased following tacrolimus therapy (P = 0.04 for both). Average FK506 trough level over the treatment period was significantly associated with change in fibrosis (Spearman's rho = 0.67 and P = 0.02).

CONCLUSIONS

This is some of the first histological data concerning tacrolimus nephrotoxicity in childhood nephrotic syndrome. Although the role of the natural progression of the underlying disease in the observed change is not definitively clear, the changes seen are in keeping with the known nephrotoxic effects of FK506 demonstrated in renal transplant. This increase is small when presented as a median change. However, there were a number of children who had a larger change in fibrosis. The factors predictive of interstitial fibrosis while on FK506 are not well defined; the findings from this study suggest that FK506 level may be a factor. Given the observations and limitations of the few published studies, there is an obvious need for further study in a large multicenter prospective trial.