Efficacy and safety of long-term repeated use of rituximab in pediatric patients with nephrotic syndrome

BACKGROUND

We aimed to investigate the efficacy and safety of repeated use of rituximab (RTX) in pediatric patients with nephrotic syndrome (NS).

METHODS

Retrospective review of 50 patients with steroid-dependent NS (SDNS) who had received more than three cycles of RTX was conducted; each consisted of one to four infusions until B lymphocytes were depleted.

RESULTS

The median age of starting the first RTX cycle was 12.4 years (interquartile ranges (IQR) 10.2-14.6). During a median follow-up period of 6.3 (IQR 3.6-8.6) years, patients received a median of 5.0 RTX cycles (IQR 4.0-7.3). The number of relapses decreased from a median of 2.0 relapses per year (IQR 1.0-3.0) to 0.2 relapses per year (IQR 0.0-0.5) after long-term RTX treatments (P < 0.001). Longer relapse-free periods were associated with more than four RTX cycles, longer B-cell depletion, older age at each RTX treatment, and lower cholesterol levels. B lymphocytes recovered to 1% at a median of 5.9 months (95% confidence interval 5.7-6.1) after RTX administration. Factors related to a longer period of B-cell depletion included more than five RTX cycles, a higher dose of RTX, older age at treatment, and concurrent use of antimetabolites. During repeated RTX treatments, 8.0%, 6.0%, and 2.0% of patients developed hypogammaglobulinemia, severe infection, and severe neutropenia, respectively.

CONCLUSIONS

Long-term repeated use of RTX may be effective and safe in pediatric NS patients. Furthermore, the redosing of RTX could be chosen by considering predictive factors for relapse-free and B-cell depletion periods.

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.

Update on the treatment of steroid-sensitive nephrotic syndrome

Steroid-sensitive nephrotic syndrome (SSNS) is a rare condition that develops primarily in preadolescent children after the age of 1 year. Since the 1950s, oral corticosteroids have been the mainstay of treatment of all children presenting with nephrotic syndrome, with most patients responding within 4 weeks to an oral course of prednisone (PDN). However, corticosteroids have important side effects and 60-80 % of patients relapse, developing frequently relapsing or steroid-dependent forms. For these reasons, many patients require second-line steroid-sparing immunosuppressive medications that have considerably improved relapse-free survival, while avoiding many PDN-related toxicities. Since most patients will eventually heal from their disease with a normal kidney function, the morbidity of SSNS is primarily related to side effects of drugs that are used to maintain prolonged remission. Therefore, treatment is essentially based on balancing the use of different drugs to achieve permanent remission with the lowest cumulative number of side effects. Treatment choice is based on the severity of SSNS, on patient age, and on drug tolerability. This review provides an update of currently available therapeutic strategies for SSNS.

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.

[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.

[Childhood steroid-dependent idiopathic nephrotic syndrome: Predictive factors for the need of immunosuppressive treatment]

BACKGROUND AND AIMS

More than half of the children with idiopathic nephrotic syndrome become steroid-dependent (or frequent relapsers) and will later require the use of complementary treatment aiming to reduce steroids' side effects and to limit the number of proteinuria relapses. It appears important to identify these children as early as possible in order to adapt their treatment. The aim of this study was to analyze the population of children, under 18 years of age, diagnosed between 1/01/2000 and 31/05/2015 with an idiopathic nephrotic syndrome and followed at the Montpellier University Hospital to search for criteria predictive of steroid-sparing agent use.

METHODS

In this retrospective study of children with idiopathic nephrotic syndrome, the exclusion criteria were primary steroid resistance and children with no proteinuria relapse after diagnosis.

RESULTS

Eighty-four children (54 boys) were included in this study. The mean follow-up duration was 5.5 years (0.75-16). The mean age at diagnosis was 4.6 years. Sixty-five children (77%) received at least one steroid-sparing agent during their follow-up, within a mean 10 months after diagnosis. In these patients, the first relapse of the disease occurred earlier when compared with the children who were maintained on steroid alone (4 months vs 7 months; P<0.001). The use of methylprednisolone pulses to obtain a remission, the cumulative dose of steroid treatment, and the number of proteinuria relapses were also significantly correlated with the use of complementary immunosuppressive therapy.

CONCLUSION

We found no predictive criteria of the use of steroid-sparing agents at diagnosis in our population of children. Nevertheless, with the steroid regimen used, the time within which the first proteinuria relapse occurred appears to be a significant criterion for the secondary use of a steroid-sparing agent. These data should be taken into account when choosing the treatment regimen.

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.

[Comparison of therapeutic effects of prednisone combined with mycophenolate mofetil versus cyclosporin A in children with steroid-resistant nephrotic syndrome]

OBJECTIVE

To compare the therapeutic effects of prednisone combined with mycophenolate mofetil (MMF) versus cyclosporin A (CsA) in children with steroid-resistant nephrotic syndrome (SRNS).

METHODS

The clinical data of 164 SRNS children who were treated with prednisone combined with MMF or CsA between January 2004 and December 2013 were collected, and the clinical effect of prednisone combined with MMF (MMF group, 112 children) or CsA (CsA group, 52 children) was analyzed retrospectively.

RESULTS

At 1 month after treatment, the CsA group had a significantly higher remission rate than the MMF group (67.3% vs 42.9%; P<0.05). At 3 months after treatment, the CsA group also had a significantly higher remission rate than the MMF group (78.8% vs 63.3%; P<0.05). The 24-hour urinary protein excretion in both groups changed significantly with time (P<0.05) and differed significantly between the two groups (P<0.05). There were no serious adverse events in the two groups.

CONCLUSIONS

Prednisone combined with MMF or CsA is effective and safe for the treatment of SRNS in children, and within 3 months of treatment, CsA has a better effect than MMF.

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.

Urinary IgG and α2-macroglobulin are powerful predictors of outcome and responsiveness to steroids and cyclophosphamide in idiopathic focal segmental glomerulosclerosis with nephrotic syndrome

Objective. To assess whether high-molecular-weight proteins excretion predicts outcome and therapy-responsiveness in patients with FSGS and nephrotic syndrome. Research Design and Methods. Thirty-eight patients measured at biopsy fractional excretion of IgG (FEIgG) and urinary α2-macroglobulin/creatinine ratio (α2m/C). Low and high risk groups were defined by cutoffs assessed by ROC analysis. In all patients first-line therapy was with steroids alone or in combination with cyclophosphamide. Results. α2m/C and FEIgG were correlated with segmental sclerosis (r = 0.546; r = 0.522). Twenty-three patients (61%) entered Remission and 9 (24%) progressed to ESRD. Comparing low and high risk groups, by univariate analysis remission was predicted by FEIgG (77% versus 25%, P = 0.016) and α2m/C (81% versus 17%, P = 0.007) and ESRD at best by FEIgG (0% versus 75%, P < 0.0001) and α2m/C (4% versus 67%, P < 0.0001). By multivariate analysis FEIgG was the only independent predictor of remission and α2m/C the most powerful predictor of ESRD. Low and high risk groups of FEIgG and α2m/C in combination had very high predictive value of sustained remission and ESRD in response to therapy. Conclusions. FEIgG and α2m/C are powerful predictors of outcome and responsiveness to steroids and cyclophosphamide; their predictive value, if validated in prospective studies, may be useful in clinical practice suggesting first-line alternative treatments in high risk patients.

Mycophenolate mofetil versus cyclosporin A in children with frequently relapsing nephrotic syndrome

The severe side effects of long-term corticosteroid or cyclosporin A (CsA) therapy complicate the treatment of children with frequently relapsing steroid-sensitive nephrotic syndrome (FR-SSNS). We conducted a randomized, multicenter, open-label, crossover study comparing the efficacy and safety of a 1-year treatment with mycophenolate mofetil (MMF; target plasma mycophenolic acid trough level of 1.5-2.5 µg/ml) or CsA (target trough level of 80-100 ng/ml) in 60 pediatric patients with FR-SSNS. We assessed the frequency of relapse as the primary endpoint and evaluated pharmacokinetic profiles (area under the curve [AUC]) after 3 and 6 months of treatment. More relapses per patient per year occurred with MMF than with CsA during the first year (P=0.03), but not during the second year (P=0.14). No relapses occurred in 85% of patients during CsA therapy and in 64% of patients during MMF therapy (P=0.06). However, the time without relapse was significantly longer with CsA than with MMF during the first year (P<0.05), but not during the second year (P=0.36). In post hoc analysis, patients with low mycophenolic acid exposure (AUC <50 µg⋅h/ml) experienced 1.4 relapses per year compared with 0.27 relapses per year in those with high exposure (AUC>50 µg⋅h/ml; P<0.05). There were no significant differences between groups with respect to BP, growth, lipid levels, or adverse events. However, cystatin clearance, estimated GFR, and hemoglobin levels increased significantly with MMF compared with CsA. These results indicate that MMF is inferior to CsA in preventing relapses in pediatric patients with FR-SSNS, but may be a less nephrotoxic treatment option.

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.

Rituximab for childhood refractory nephrotic syndrome

Several therapies including immunosuppressive agents have been shown to be effective and safe for frequently relapsing nephrotic syndrome/steroid-dependent nephrotic syndrome (FRNS/SDNS) and steroid-resistant nephrotic syndrome in children. It is evident, however, that a substantial number of children are still refractory to treatment despite these therapies. Rituximab is a chimeric monoclonal antibody, which inhibits CD20-mediated B-cell proliferation and differentiation. It was first introduced for the treatment of B-cell non-Hodgkin's lymphoma and was subsequently administered to patients with autoimmune diseases, such as rheumatoid arthritis, lupus erythematosus, or immunocomplex glomerulonephritis. Recently, a number of case reports and non-controlled clinical trials have suggested that rituximab may be effective for children with refractory nephrotic syndrome. Controlled prospective trials, however, are required to establish the value of rituximab in refractory nephrotic syndrome. The purpose of the present study was therefore to evaluate the efficacy and safety of rituximab in childhood-onset refractory nephrotic syndrome. The Research Group of Childhood-onset Refractory Nephrotic Syndrome (RCRNS) conducted a randomized, double-blind, placebo-controlled, multi-center clinical trial (RCRNS-01) and an open-label, multi-center, pharmacokinetic clinical trial (RCRNS-02). These two trials were investigator-initiated, registration-directed clinical trials designed to apply Ministry of Health, Labour and Welfare approval for the use of rituximab for childhood-onset refractory FRNS/SDNS in Japan. RCRNS-01 could be the first study to clarify whether rituximab is effective and safe for childhood-onset refractory FRNS/SDNS.

Cyclophosphamide in steroid-dependent nephrotic syndrome

In order to determine the long-term effects of cyclophosphamide (CPO) and to identify parameters associated with sustained remission, we retrospectively studied the data from 90 patients with steroid-dependent nephrotic syndrome (SDNS) who received a single course of oral cyclophosphamide (2 mg/kg/day for 10 to 12 weeks). The median follow-up period after CPO was 5.5 years (interquartile range 3.2-8.5). Sustained remission reached the cumulative rate of 57% at 1 year, 42% at 2 years, and 31% at 5 years. For the patients who relapsed, the median threshold dose of prednisone between CPO initiation and first relapse has significantly decreased (22.1 mg/kg/day versus 4.9 mg/kg/day, p < 0.001). No further immunosuppressive agent was required in 60% of all patients. Young age at CPO initiation was associated with a lower rate of sustained remission (p < 0.001). Age at diagnosis of nephrotic syndrome, gender, cumulative dose of CPO (in mg/kg), and level of steroid dependence at CPO initiation did not influence the outcome. The incidence of side effects was low. These findings suggest that despite the wide use of new immunosuppressive agents, a short course of CPO remains an effective second-line therapy in SDNS patients. Optimal efficiency was observed in children over 7.5 years.