Long-term follow-up after cyclophosphamide therapy in steroid-dependent nephrotic syndrome

IPNA clinical practice recommendations for the diagnosis and management of children with steroid-sensitive nephrotic syndrome

Idiopathic nephrotic syndrome is the most frequent pediatric glomerular disease, affecting from 1.15 to 16.9 per 100,000 children per year globally. It is characterized by massive proteinuria, hypoalbuminemia, and/or concomitant edema. Approximately 85-90% of patients attain complete remission of proteinuria within 4-6 weeks of treatment with glucocorticoids, and therefore, have steroid-sensitive nephrotic syndrome (SSNS). Among those patients who are steroid sensitive, 70-80% will have at least one relapse during follow-up, and up to 50% of these patients will experience frequent relapses or become dependent on glucocorticoids to maintain remission. The dose and duration of steroid treatment to prolong time between relapses remains a subject of much debate, and patients continue to experience a high prevalence of steroid-related morbidity. Various steroid-sparing immunosuppressive drugs have been used in clinical practice; however, there is marked practice variation in the selection of these drugs and timing of their introduction during the course of the disease. Therefore, international evidence-based clinical practice recommendations (CPRs) are needed to guide clinical practice and reduce practice variation. The International Pediatric Nephrology Association (IPNA) convened a team of experts including pediatric nephrologists, an adult nephrologist, and a patient representative to develop comprehensive CPRs on the diagnosis and management of SSNS in children. After performing a systematic literature review on 12 clinically relevant PICO (Patient or Population covered, Intervention, Comparator, Outcome) questions, recommendations were formulated and formally graded at several virtual consensus meetings. New definitions for treatment outcomes to help guide change of therapy and recommendations for important research questions are given.

Second and Third Generational Advances in Therapies of the Immune-Mediated Kidney Diseases in Children and Adolescents

Therapy of immune-mediated kidney diseases has evolved during recent decades from the non-specific use of corticosteroids and antiproliferative agents (like cyclophosphamide or azathioprine), towards the use of more specific drugs with measurable pharmacokinetics, like calcineurin inhibitors (cyclosporine A and tacrolimus) and mycophenolate mofetil, to the treatment with biologic drugs targeting detailed specific receptors, like rituximab, eculizumab or abatacept. Moreover, the data coming from a molecular science revealed that several drugs, which have been previously used exclusively to modify the upregulated adaptive immune system, may also exert a local effect on the kidney microstructure and ameliorate the functional instability of podocytes, reducing the leak of protein into the urinary space. The innate immune system also became a target of new therapies, as its specific role in different kidney diseases has been de novo defined. Current therapy of several immune kidney diseases may now be personalized, based on the detailed diagnostic procedures, including molecular tests. However, in most cases there is still a space for standard therapies based on variable protocols including usage of steroids with the steroid-sparing agents. They are used as a first-line treatment, while modern biologic agents are selected as further steps in cases of lack of the efficacy or toxicity of the basic therapies. In several clinical settings, the biologic drugs are effective as the add-on therapy.

Oral cyclophosphamide therapy in 100 children with steroid-sensitive nephrotic syndrome: experience from a developing country

BACKGROUND

Oral cyclophosphamide (CYP) is an important therapeutic agent in treatment of steroid-sensitive nephrotic syndrome having a steroid-dependent (SD) or frequent relapsing (FR) course. This retrospective observational study aimed to determine response to oral CYP and factors associated with positive response in these patients.

METHODS

We studied 100 children (male; 75) with FR (19%) and SD (81%) NS treated with CYP in the Pediatric Nephrology clinic. Responders were defined as children in whom steroids were stopped for at least 6 months following CYP and factors affecting response were analysed. Relapse-free survival was estimated by Kaplan-Meier method.

RESULTS

Median age at onset of NS was 3 years (IQR 2-5.2). Median age at CYP was 5.7 years (IQR 3.7-7.9). Fifty percent of patients were in the responder group at 6 months of CYP. Relapse-free survival post CYP therapy was 31% at 1 year, 11% at 2 years. Factors predicting good response were age at onset of NS > 3 years with 61.2% response at 6 months (p = 0.028) and older age at CYP initiation (> 5 years) with 61% response (p = 0.008). Multivariate regression analysis showed age at start of CYP > 5 years was an independent factor for good response (p = 0.044, OR = 2.903, CI -1.03 to 8.18).

CONCLUSIONS

Judicious selection of patients, especially with age of onset of NS more than 3 years and initiation of CYP after age of 5 years, can predict better response in this group of patents.

A global antiB cell strategy combining obinutuzumab and daratumumab in severe pediatric nephrotic syndrome

BACKGROUND

Steroid-sensitive nephrotic syndrome (SSNS) is, in most patients, a chronic disease with 80% experiencing at least one relapse after first flare. B cell depletion using rituximab is effective in preventing relapse in steroid-dependent (SDNS) patients but fails to maintain long-term remission following B cell recovery, possibly due to development of autoreactive long-lived plasma cells. We investigated sequential combination of antiCD20 antibody targeting all B cell subsets, and antiCD38 antibody with high plasma cell cytotoxicity in patients with uncontrolled SDNS after failure of one or several attempts at B cell depletion.

METHODS

Fourteen patients with median disease duration 7.8 years received 1000 mg/1.73 m² obinutuzumab followed by 1000 mg/1.73 m² daratumumab 2 weeks later. Oral immunosuppression was discontinued within 6 weeks, and biological monitoring performed monthly until B cell recovery.

RESULTS

Median age at treatment was 11.0 [IQR 10.4-14.4] years. B cell depletion was achieved in all patients, and B cell reconstitution occurred in all at median 9.5 months after obinutuzumab injection. After median follow-up 20.3 months (IQR 11.5-22.6), 5/14 patients relapsed including 4 within 100 days following B cell repletion. Relapse-free survival was 60% at 24 months from obinutuzumab infusion. Mild infusion reactions were reported in 3/14 patients during obinutuzumab and 4/14 during daratumumab infusions. Mild transient neutropenia (500-1000/mm³) occurred in 2/14 patients. Intravenous immunoglobulins were given to 12/14 patients due to hypogammaglobulinemia. Low IgA and IgM levels were noted in 8 and 14 patients, respectively. No severe infection was reported.

CONCLUSION

Global antiB cell strategy combining obinutuzumab and daratumumab induces prolonged peripheral B cell depletion and remission in children with difficult-to-treat SDNS.

Treating the idiopathic nephrotic syndrome: are steroids the answer?

The use of steroids in idiopathic nephrotic syndrome is the major discovery of the twentieth century in the field of pediatric nephrology. At onset of the twenty-first century, steroids remain the first line of treatment at first flare. All the protocols to treat the first flare are similar by a common sequence including a first phase of daily prednisolone/prednisone at a dose of 60 mg/m²/day for at least 4 weeks followed by an alternate-day regimen for several weeks. It appears that a cumulated dose of 2240 mg/m² given in 8 weeks at the first flare without tapering sequence is not inferior to increased dose and duration in terms of prevalence of frequent relapsers and the subsequent cumulated dose of steroids at 24 months of follow-up. A higher cumulated dose might only be interesting in patients aged below 4 years although a formal demonstration is still missing. Several retrospective studies are concordant to suggest that intravenous methylprednisolone pulses are useful to reach a full urinary remission in case of oral resistance to 4 weeks of oral prednisone/prednisolone. A majority of patients have multiple relapses after the treatment of the first flare and half meet the definition of steroid dependency. In those patients, long-lasting alternate-day prednisone/prednisolone therapy does not lead to long-lasting remission, opening the question of the best strategy of immunosuppression.

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.

[Cyclophosphamide in idiopathic nephrotic syndrome: Outcome and outlook]

INTRODUCTION

Cyclophosphamide (CYP) has been used for over 40 years in patients with steroid-sensitive nephrotic syndrome (NSSS) presenting frequent relapses (NSRF) or steroid dependence (NSSD). However, the long-term success of treatment with cyclophosphamide is difficult to predict. The objectives of this study are to determine long-term outcomes of cyclophosphamide and identify the factors associated with sustained remission.

METHODS

We retrospectively studied the data from 50 patients with idiopathic nephrotic syndrome, treated by oral cyclophosphamide and followed at service of pediatric for more than 8 years for idiopathic nephrotic syndrome and related factors for survival without relapse were evaluated by univariate analysis.

RESULTS

The median age at the time of diagnosis was 4.3 years, and median follow-up time was 1.7 years with the median of 8 years at the first use of CYC. Patients had received a median cumulative dose of 168mg/kg. At the end of follow-up, 38% of patients entered into remission after using CYC while 62% failed to respond and further relapses then occur. The median time of stopping corticosteroid therapy was three month. The survival without relapse was respectively 56% (28 patients), 52% (26 patients), 48% (24 patients), and 38% (19 patients), at 6 months, one year, two years and more than two years. In univariate analysis, the survival without relapse was related to the age at the moment of starting the therapy par CYC (the median was 5 months for an age < 8 years and 41 months for an age≥8 years; P=0.049), the type of nephrotic syndrome [36 months for SNRF, 4 months for NSSD and nephrothic syndrome steroid resistant (NSSR); P=0.068], and the histological lesion (6 months for diffuse mesangial proliferation, 2 months for segmental glomerulosclerosis; P=0.009). The age at the moment of diagnosis, the sex and the cumulative dose of CYC did not have significant influence.

CONCLUSION

The results presented in this study suggest the use of oral cyclophosphamide for short period remain second line effective therapy. Further well-designed trials are required to evaluate the efficacy of other steroid-sparing agents.

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.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Mycophenolate mofetil in steroid-dependent idiopathic nephrotic syndrome

BACKGROUND

Prospective studies have established the mycophenolate mofetil (MMF) efficiency in childhood idiopathic nephrotic syndrome (INS) but reports on the long-term outcome are lacking. Moreover, the search for factors influencing its efficiency would be useful to define its place among the other treatments.

METHODS

We performed a monocentric retrospective study including 96 children with steroid-dependent INS followed for 4.7 years (median) (IQ 3-6) after the onset of MMF treatment. The characteristics of responder patients (n = 74), as defined by a 50 % decrease of relapse rate and/or a 60 % decrease of steroid dose, and of non-responder patients (n = 22) were compared by univariate analysis and multivariate logistic regression.

RESULTS

Withdrawal of prednisone was achieved in 48/96 patients after a median duration of 18.1 months (IQ 7.8-30.0) of MMF. Only 26/48 patients did not relapse under MMF alone. After MMF was stopped in these patients, only six remained in remission without any treatment at last follow-up. Responders had a shorter time to remission at the first flare (9.5 vs. 15 days, p = 0.02), a shorter disease duration prior to the onset of MMF (22.2 vs. 94.5 months, p = 0.001), and were younger at the MMF initiation (6.7 vs. 10.1 years, p = 0.02) than non-responder patients. The age of MMF initiation was an independent factor associated with efficiency (OR = 0.80, 95 % CI [0.69, 0.93], p < 0.01).

CONCLUSIONS

MMF is more efficient in young patients treated early in the disease course. Nevertheless, MMF has no remnant effect while nearly all patients relapsed after withdrawal of the drug.

Ethnic Differences in Incidence and Outcomes of Childhood Nephrotic Syndrome

BACKGROUND AND OBJECTIVES

Ethnic differences in outcomes among children with nephrotic syndrome are unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a longitudinal study at a single regional pediatric center comparing ethnic differences in incidence from 2001 to 2011 census data and longitudinal outcomes, including relapse rates, time to first relapse, frequently relapsing disease, and use of cyclophosphamide. Among 711 children, 24% were European, 33% were South Asian, 10% were East/Southeast Asian, and 33% were of other origins.

RESULTS

Over 10 years, the overall incidence increased from 1.99/100,000 to 4.71/100,000 among children ages 1-18 years old. In 2011, South Asians had a higher incidence rate ratio of 6.61 (95% confidence interval, 3.16 to 15.1) compared with Europeans. East/Southeast Asians had a similar incidence rate ratio (0.76; 95% confidence interval, 0.13 to 2.94) to Europeans. We determined outcomes in 455 children from the three largest ethnic groups with steroid-sensitive disease over a median of 4 years. South Asian and East/Southeast Asian children had significantly lower odds of frequently relapsing disease at 12 months (South Asian: adjusted odds ratio; 0.55; 95% confidence interval, 0.39 to 0.77; East/Southeast Asian: adjusted odds ratio; 0.42; 95% confidence interval, 0.34 to 0.51), fewer subsequent relapses (South Asian: adjusted odds ratio; 0.64; 95% confidence interval, 0.50 to 0.81; East/Southeast Asian: adjusted odds ratio; 0.47; 95% confidence interval, 0.24 to 0.91), lower risk of a first relapse (South Asian: adjusted hazard ratio, 0.74; 95% confidence interval, 0.67 to 0.83; East/Southeast Asian: adjusted hazard ratio, 0.65; 95% CI, 0.63 to 0.68), and lower use of cyclophosphamide (South Asian: adjusted hazard ratio, 0.82; 95% confidence interval, 0.53 to 1.28; East/Southeast Asian: adjusted hazard ratio, 0.54; 95% confidence interval, 0.41 to 0.71) compared with European children.

CONCLUSIONS

Despite the higher incidence among South Asians, South and East/Southeast Asian children have significantly less complicated clinical outcomes compared with Europeans.

Evaluation of mycophenolate mofetil or tacrolimus in children with steroid sensitive but frequently relapsing or steroid-dependent nephrotic syndrome

AIM

Approximately 30-40% of children with steroid sensitive nephrotic syndrome have frequently relapsing nephrotic syndrome (FRNS) or steroid-dependent nephrotic syndrome (SDNS). Mycophenolate mofetil (MMF) and tacrolimus (TAC) are often alternative treatment choices for these patients.

METHODS

A single-center prospective study was conducted to compare the efficacy of MMF or TAC in reducing relapses and maintaining remission in children with FRNS or SDNS. Of the 72 recruited patients, either MMF (20∼30 mg/kg/d, n = 34) or TAC (0.05∼0.15 mg/kg/d, n = 38) was administered for 12 months.

RESULTS

The mean 6-month relapse rates decreased from 2.56 episodes before therapy to 0.76 episodes in the first 6 months after therapy (c(2) = 44.362, p < 0.001) and 0.67 in the next 6 months (c(2) = 37.817, p < 0.001) in the MMF group. In the TAC group, the mean 6-month relapse rates decreased from 2.39 episodes before therapy to 0.41 episodes in the first 6 months after therapy (c(2) = 62.242, p < 0.001) and 0.42 in next 6 months (c(2) = 67.482, p < 0.001). No significant difference in the relapse rate was found between the groups (before therapy, c(2) = 0.902, p = 0.637; first 6 months, c(2) = 5.358, p = 0.147; second 6 months, c(2) = 4.089, p = 0.252). And there was also no significant difference in cumulative sustained remission and the incidence of adverse events between two groups.

CONCLUSIONS

In combination with low-dose steroids, MMF or TAC presented similar efficacy in maintaining remission in children with FRNS/SDNS in the present study. Therapy with MMF or TAC is a promising strategy with a moderate risk of side effects in children who are steroid sensitive but have FRNS/SDNS.

Morbidity in children with frequently relapsing nephrosis: 10-year follow-up of a randomized controlled trial

BACKGROUND

To investigate the long-term outcome in children with frequently relapsing nephrotic syndrome (FRNS) we conducted a follow-up of a previous randomized controlled trial (RCT) 10 years after the initiation of the treatment protocol.

METHODS

We previously conducted an RCT on the efficacy of cyclosporine for treating children with FRNS. After 2 years of treatment, a recommended a management protocol of steroids, and immunosuppressants was provided.

RESULTS

Valid information was available for 46 of the 56 patients (82.1 %) enrolled in the original RCT. The median follow-up period was 10.3 years from the start of protocol treatment with cyclosporine. At last follow-up (mean age 18.7 years), only ten patients (21.7 %) showed disease-free remission (no relapse for at least 2 years). In contrast, 23 (50.0 %) continued to relapse frequently or were on immunosuppressants, eight patients (17.4 %) had infrequent relapses without immunosuppressants. Adverse effects attributable to treatment included short stature (6 patients), osteoporosis (six patients), obesity (4 patients), cataracts (3 patients) and hypertension (3 patients). No lethal event or renal dysfunction occurred during follow-up.

CONCLUSIONS

This 10-year follow-up study shows that most children with FRNS experience relapses after 2 years of cyclosporine treatment, in adolescence and into adulthood. Outcomes in terms of life expectancy and renal function are favorable.

Assaying environmental nickel toxicity using model nematodes

Although nickel exposure results in allergic reactions, respiratory conditions, and cancer in humans and rodents, the ramifications of excess nickel in the environment for animal and human health remain largely undescribed. Nickel and other cationic metals travel through waterways and bind to soils and sediments. To evaluate the potential toxic effects of nickel at environmental contaminant levels (8.9-7,600 µg Ni/g dry weight of sediment and 50-800 µg NiCl₂/L of water), we conducted assays using two cosmopolitan nematodes, Caenorhabditis elegans and Pristionchus pacificus. We assayed the effects of both sediment-bound and aqueous nickel upon animal growth, developmental survival, lifespan, and fecundity. Uncontaminated sediments were collected from sites in the Midwestern United States and spiked with a range of nickel concentrations. We found that nickel-spiked sediment substantially impairs both survival from larval to adult stages and adult longevity in a concentration-dependent manner. Further, while aqueous nickel showed no adverse effects on either survivorship or longevity, we observed a significant decrease in fecundity, indicating that aqueous nickel could have a negative impact on nematode physiology. Intriguingly, C. elegans and P. pacificus exhibit similar, but not identical, responses to nickel exposure. Moreover, P. pacificus could be tested successfully in sediments inhospitable to C. elegans. Our results add to a growing body of literature documenting the impact of nickel on animal physiology, and suggest that environmental toxicological studies could gain an advantage by widening their repertoire of nematode species.

Is cyclophosphamide effective in patients with IgM-positive minimal change disease?

BACKGROUND

We analyzed the impact of immunoglobulin M (IgM) positivity on the relapse-free interval post completed course of cyclophosphamide (CYC) treatment in patients with steroid-dependent nephrotic syndrome (SDNS) and minimal change disease (MCD).

METHODS

This was a retrospective chart review of all children who received CYC for SDNS and MCD between 1988 and 2009. Patients were divided into three groups based on kidney biopsy: MCD without immunoglobulin M (IgM) positivity (IgM-), MCD with IgM-positive immunofluorescence (IF) only (IgM+), and MCD with IgM-positive IF and electron-dense deposits on electron microscopy (IgM++). The relapse-free time interval to the first relapse post-CYC therapy or up to 48 months of follow-up (if no relapse occurred) was used for survival analysis.

RESULTS

Forty children aged 1.5-12.3 years (15 were IgM-, 16 were IgM+, 9 were IgM++) received a cumulative CYC dose of 175 ± 30 mg/kg. The overall relapse-free survival time was 75 % at 12 months, 64 % at 24 months, 59 % at 36 months, and 56 % at 48 months, with no significant differences between the IgM groups (p = 0.80).

CONCLUSIONS

Based on our results, we conclude that more than 50% of our SDNS patients with MCD remained relapse-free 4 years post-CYC treatment. No significant difference in the response to CYC was observed between patients with or without IgM positivity.

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.

Mycophenolate mofetil for steroid-dependent nephrotic syndrome: a phase II Bayesian trial

Mycophenolate mofetil (MMF) has emerged as a new therapeutic option in steroid-dependent nephrotic syndrome (SDNS). We conducted a phase II Bayesian trial of MMF in children with SDNS. Phase II trials, usually single-arm studies, investigate the effect of new treatments. Standard Fleming's procedure relies on observed results (relapse rate during the trial), whereas Bayesian approach combines observed results with prior information (expected relapse rate according to prior studies and clinical experience). All patients were required to have received prior alkylating-agent treatment. Sixty-seven percent of them had also received levamisole. Patients received MMF (1,200 mg/m(2)/day) and prednisone according to a defined schedule [reduction of alternate-day (e.o.d) dose to 50% of pre-MMF dose at 3 months, 25% at 6 months]. Twenty-four children (median age 6.0 years, 2.8-14.4) entered the study and 23 completed it. Bayesian analysis showed that adding four patients would not change significance of results, allowing stopping inclusions. Four patients relapsed during the first 6 months (estimated probability 17.6%, 95% credibility interval: 5.4-35.0%) and two at months 8 and 11.5. In the 19 patients free of relapse during the first 6 months, median (Q1-Q3) prednisone maintenance dose decreased from 25 (10-44) to 9 (7.5-11.2) mg/m(2) e.o.d (p < 0.001) and cumulative dose from 459 (382-689) to 264 (196-306) mg/m(2)/month (p < 0.001) before and on MMF respectively. Pre-MMF patient characteristics and MMF pharmacokinetics did not differ between patients with or without relapse. MMF reduces relapse rate and steroid dose in children with SDNS and should be proposed before cyclosporine and cyclophosphamide.