Summary
Background and objectives
Although the safety and efficacy of cyclosporine in children with frequently relapsing nephrotic syndrome (FRNS) have been confirmed, no prospective follow-up data on relapse after cyclosporine have appeared. This study is a prospective follow-up trial after 2-year treatment with cyclosporine to investigate cyclosporine dependency after its discontinuation.
Design, setting, participants, & measurements
Participants who had undergone 2-year protocol treatment with microemulsified cyclosporine for FRNS between January 2000 and December 2005 were followed for an additional 2 years. The primary end point was relapse-free survival after the complete discontinuation of cyclosporine, and the secondary end point was regression-free survival (time to regression to FRNS).
Results
After exclusion of 7 patients who showed regression to FRNS during the 2-year treatment period, 49 children (median age, 6.5 years) were followed, and classified as children without (n=32; group A) and with (n=17; group B) relapse during the initial cyclosporine treatment. Overall, relapse-free survival probability at 24 months after cyclosporine discontinuation was 15.3% and regression to FRNS-free survival probability was 40.8%. By group, the probability of relapse-free survival was significantly higher in group A (17.9%) than in group B (8.3%) (P<0.001).
Conclusions
Children with FRNS who receive cyclosporine are at high risk of relapse after discontinuation, particularly those who experience relapse during cyclosporine treatment.
Introduction
The safety and efficacy of cyclosporine in children with frequently relapsing nephrotic syndrome (FRNS) and steroid-dependent nephrotic syndrome (SDNS) have been demonstrated in a number of studies, including a randomized controlled trial (1–8). We previously showed that microemulsified cyclosporine administered according to our treatment protocol is safe and effective in children with FRNS (2). In that study, the probability of relapse-free survival at month 24 was 58.1% and the probability of regression (to frequently relapsing nephrotic syndrome)–free survival at month 24 was 88.5%. Cyclosporine nephrotoxicity was detected in only 8.6% of patients who underwent renal biopsy after 2 years of treatment. Nevertheless, an important limitation of this treatment is cyclosporine dependency, namely the frequent relapse of nephrosis after discontinuation(9–12). Most studies of relapse after cyclosporine to date have been retrospective, however, and no prospective evaluation in these patients has been reported.
Several factors have been linked to a prolonged disease course in children with FRNS, including age at the onset of nephrotic syndrome (13,14) and number of relapses or steroid dependency (13,15,16). However, factors associated with relapse after cyclosporine have not been clearly established. Furthermore, it is unclear whether infrequent relapse during cyclosporine treatment is associated with disease activity. Identification of risk factors would allow better treatment decisions, particularly in predicting patients at highest risk of regression of FRNS.
Here, we conducted a prospective follow-up study of the participants of our previous clinical trial to evaluate the rate of relapse of nephrosis and FRNS after the complete discontinuation of cyclosporine. We also evaluated factors associated with relapse.
Materials and Methods
Previous Trial
This study was a prospective follow-up analysis of a previous multicenter trial that evaluated the efficacy and safety of 2-year treatment with cyclosporine in children with FRNS between January 2000 and December 2005. Entry criteria and protocol have been detailed elsewhere (2). Briefly, children aged 1–18 years with FRNS who had idiopathic nephrotic syndrome were eligible. Patients with a history of cyclosporine treatment were excluded. Microemulsified cyclosporine (Neoral; Novartis, Basel, Switzerland) was administered for 2 years under trough control. For the first 6 months, all patients were administered a dose that maintained a whole-blood trough level between 80 and 100 ng/ml of cyclosporine. The dose was adjusted over the next 18 months to maintain a trough level between 60 and 80 ng/ml. Maintenance prednisolone was not prescribed. After 2 years of treatment, all patients were scheduled to undergo renal biopsy, and cyclosporine was stopped by dose tapering at a rate of 0.5–1.0 mg/kg per week.
Follow-Up Study
This study was conducted under a prospective, follow-up design in 21 participating institutions. Eligibility was restricted to patients who completed 2-year treatment with cyclosporine in the previous trial. Follow-up was conducted for 2 years, beginning from the time of complete cessation of cyclosporine. Patients who experienced relapse of nephrosis during the study period were administered prednisolone at 2 mg/kg per day in three divided doses (maximum, 80 mg/d) until remission, and then a single dose of prednisolone at 2 mg/kg in the morning on alternate days for 2 weeks, 1 mg/kg on alternate days for the next 2 weeks, and 0.5 mg/kg on alternate days for a final 2 weeks. Children who then met the criteria for FRNS received cyclosporine by the same protocol as in the original trial (2), or cyclophosphamide (2.5 mg/kg per day) for 8–12 weeks if cyclosporine nephrotoxicity was found on renal biopsy. Use of antihypertensive drugs was not restricted, including angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers. Data were collected from the participating institutions for analysis at 1-year intervals, and included body weight and height, BP, medications given, blood analysis (complete blood cell count, blood chemistry), and urine tests (urinalysis, quantitative proteinuria).
The design and execution of this study were in accordance with the ethical standards of the Declaration of Helsinki. The protocol was approved by the ethics committee of Tokyo Metropolitan Kiyose Children’s Hospital (predecessor of Tokyo Metropolitan Children’s Medical Center). Informed consent was obtained from all patients or their parents. This study was registered in the University Hospital Medical Information Network public trials registry (ID C000000010; http://www.umin.ac.jp/ctr/index.htm).
Criteria and Definitions
The criteria for and definitions of nephrotic syndrome, remission, and relapse were in accordance with the International Study of Kidney Disease in Children (17). FRNS was defined as ≥2 relapses of nephrotic syndrome within 6 months after the initial episode, ≥3 within any 6-month period, or ≥4 within any 12-month period. Furthermore, FRNS was defined as including SDNS and any case requiring the administration of an immunosuppressant (cyclosporine or cyclophosphamide). Steroid dependence was defined as the occurrence of two consecutive relapses during tapering of the steroid dosage or within 14 days after the cessation of administration. Renal function was evaluated as estimated GFR (eGFR) calculated using the Chronic Kidney Disease in Children study equation [0.413 × (height/serum creatinine)] (18).
Statistical Analyses
Kaplan–Meier analyses for relapse from the complete discontinuation of cyclosporine were conducted in children who had discontinued cyclosporine without the occurrence of FRNS during tapering. Analyses included time to first relapse and time to the regression to FRNS. Differences between groups were compared using the log-rank test. Risk ratio and 95% confidence interval (CI) for first recurrence and for regression to FRNS after discontinuation of cyclosporine were evaluated by Poisson regression analysis, using the explanatory variables of group (patients without [group A] and with [group B] relapse during cyclosporine treatment), age (<6 years and ≥6 years), and history of steroid dependence before the start of cyclosporine treatment. Sandwich variance was used to handle the overdispersion problem. Relapses occurring during tapering were excluded from the primary analysis of relapse-free survival, with only those occurring after the complete discontinuation of cyclosporine counted as events in the Kaplan–Meier and Poisson analyses. Patients administered cyclosporine or cyclophosphamide by their attending physician were considered to have regressed to FRNS regardless of whether they fulfilled the criteria of FRNS. All statistical analyses were performed using the SAS software package for Windows (release 9.13; SAS Institute Inc, Cary, NC). A two-sided P value <0.05 was considered statistically significant in all analyses.
Results
Data Set
Of the 62 children with FRNS in our previous study who received cyclosporine for 2 years (2), 7 regressed to FRNS during protocol treatment. Cyclosporine in these children was discontinued and their data were excluded from the present analyses. After exclusion of 6 other children, 4 due to loss to follow-up and 2 due to protocol violation (refusal to discontinue cyclosporine), this study followed and analyzed a total of 49 children (median age at complete discontinuation of cyclosporine, 6.5 years; 39 male patients) (Figure 1). Although follow-up was set at 24 months, one patient each was censored at 16, 19, and 21 months due to loss to follow-up, and six patients completed 2-year follow-up at 23 months. The participants were classified into two groups, with group A consisting of patients who had not experienced relapse during the 2-year cyclosporine treatment (n=32) and group B consisting of those who had (n=17). Basic characteristics of these children are shown in Table 1.
Figure 1.
Flow diagram. Group A included children without relapse during the initial cyclosporine treatment, whereas group B included children with relapse during the initial cyclosporine treatment. CSA, cyclosporine; FRNS, frequently relapsing nephrotic syndrome.
Table 1.
Background characteristics of study participants
| All Participants | Participants Succeeding in Discontinuing CSA | |||||
|---|---|---|---|---|---|---|
| Group | All | Group | All | |||
| A | B | A | B | |||
| Number of participants | 32 | 17 | 49 | 32 | 12 | 44 |
| Sex | ||||||
| Male | 24 | 15 | 39 | 24 | 10 | 34 |
| Female | 8 | 2 | 10 | 8 | 2 | 10 |
| Age (yr) | ||||||
| 0<6 | 12 | 5 | 17 | 12 | 4 | 16 |
| 6–12 | 17 | 6 | 23 | 17 | 6 | 23 |
| ≥12 | 3 | 6 | 9 | 3 | 2 | 5 |
| Median (IQR) | 6.4 (5.3–8.5) | 7.4 (5.9–12.1) | 6.5 (5.5–9.6) | 6.4 (5.3–8.5) | 6.5 (5.8–10.3) | 6.4 (5.4–8.5) |
| Steroid dependence | ||||||
| No | 16 | 7 | 23 | 16 | 6 | 22 |
| Yes | 16 | 10 | 26 | 16 | 6 | 22 |
| Discontinuation of CSA | ||||||
| Successful | 32 | 12 | 44 | 32 | 12 | 44 |
| Failed | 0 | 5 | 5 | |||
| CSA does tapering period (d) | ||||||
| Median (IQR) | 68 (45–94) | 77 (63–112) | 69 (48–97) | |||
| Relapse in the tapering period | ||||||
| No | 31 | 9 | 40 | |||
| Yes | 1 | 3 | 4 | |||
CSA, cyclosporine; IQR, interquartile range.
Probability of Relapse-Free and Regression-Free Survival
The median (interquartile range [IQR]) cyclosporine dose tapering period was 68 (45–94) days in group A and 77 (63–112) days in group B (Table 1). Discontinuation of cyclosporine failed in five participants due to the regression of FRNS during tapering, all of whom belonged to group B. Kaplan–Meier and Poisson analyses were conducted in the remaining 44 children (group A, n=32; group B, n=12).
Thirty-seven children experienced relapse during the follow-up period. The median (IQR) time from the complete cessation of cyclosporine to relapse was 4.3 (1.5–15.6) months for group A and 0.5 (0.0–1.1) months for group B (Table 2). In group A, 6 patients (19%) did not experience a relapse, 9 (28%) had infrequent relapses, and 17 (53%) regressed to FRNS after the discontinuation of cyclosporine. In group B, one patient (8.3%) did not experience a relapse, two (16.7%) had infrequent relapses, and nine (75%) regressed to FRNS after discontinuation. Time to regression to FRNS was 16.6 months for group A and 3.8 months for group B. The probability of relapse-free survival at 24 months from complete discontinuation was 15.3% in all children (Figure 2) and that of regression to FRNS-free survival was 40.8% (Figure 3). By group, the probability of relapse-free survival was significantly higher in group A (17.9%) than in group B (8.3%) (P<0.001, Figure 2).
Table 2.
Number of participants who experienced relapse and time to relapse
| Group | Total, n | Children Who Experienced Relapse, n (%) | Time to First Relapse (mo), Median (IQR) | Children Who Regressed to FRNS, n (%) | Time to FRNS (mo), Median (IQR) |
|---|---|---|---|---|---|
| A | 32 | 26 (81) | 4.3 (1.5–15.6) | 17 (53) | 16.6 (7.5) |
| B | 12 | 11 (92) | 0.5 (0.0–1.1) | 9 (75) | 3.8 (3.1–11.1) |
| All | 44 | 37 (84) | 2.0 (0.7–13.3) | 26 (59) | 10.2 (4.4) |
FRNS, frequently relapsing nephrotic syndrome; IQR, interquartile range.
Figure 2.
Relapse after the discontinuation of cyclosporine. Relapse-free survival probability at 2 years was 15.3% in all participants, and 17.9% in those without (group A) and 8.3% in those with (group B) relapse during cyclosporine treatment (P<0.001, log-rank test).
Figure 3.
Regression to FRNS after discontinuation of cyclosporine. Regression (to FRNS)–free survival probability at 2 years was 40.8% in all participants, and 46.7% in those without (group A) and 25.0% in those with (group B) relapse during cyclosporine treatment (P=0.05, log-rank test). FRNS, frequently relapsing nephrotic syndrome.
Factors Associated with Relapse
The recurrence rates were 0.089 per month (26 of 292.7 months) for group A and 0.30 per month (11 of 36.3 months) for group B, whereas the rate of regression to FRNS was 0.034 per month (17 of 506.2 months) and 0.074 per month (9 of 122.4 months), respectively. Results of Poisson regression are shown in Table 3. Controlling for age and steroid dependence at the beginning of cyclosporine treatment, the risk ratio of group A to B for first recurrence was 0.17 (95% CI, 0.04–0.72; P=0.02). Similar results were obtained for the risk of regression to FRNS. The risk ratio for group A compared with group B was 0.35 (95% CI, 0.15–0.83; P=0.02).
Table 3.
Poisson regression analyses for first recurrence (n=44)
| Parameter | Risk Ratio | 95% Confidence Interval | P |
|---|---|---|---|
| Group | |||
| A | 0.17 | 0.04–0.72 | 0.02 |
| B | 1.00 | — | |
| Steroid dependence | |||
| Yes | 0.31 | 0.11–0.88 | 0.03 |
| No | 1.00 | — | |
| Age at the start of follow-up (yr) | |||
| ≤6 | 1.23 | 0.44–3.40 | 0.70 |
| >6 | 1.00 | — |
Patient Survival, Renal Survival, and Growth
Information regarding patient survival and renal survival was available for 58 of 62 patients who received protocol treatment with cyclosporine. No lethal event was seen. Mean eGFR was 140.9±31.6 ml/min per 1.73 m2 (n=62, no patient with eGFR <90 ml/min per 1.73 m2) at initial study entry (beginning of cyclosporine treatment), 143.5±27.7 ml/min per 1.73 m2 (n=58, again no patient with eGFR <90) at the end of cyclosporine treatment, and 132.1±23.9 ml/min per 1.73 m2 (n=36, eGFR of one patient in group A was <90 [87.8 ml/min per 1.73 m2]) in the children analyzed in this study. One patient (group A) progressed to SRNS during the follow-up period, but finally remitted with cyclosporine. Mean (±SD) score for body height was −0.27±1.01 (n=62) at initial study entry, 0.27±0.97 (n=58) at the end of cyclosporine treatment, and 0.15±1.09 (n=42) at the end of follow-up.
Adverse Events of Steroids and Immunosuppressants
Other adverse events attributable to corticosteroids and immunosuppressants at the end of follow-up are shown in Table 4. Hypertension, defined as a requirement for antihypertensive agents during the trial, was seen in 3 of 49 (6.1%) patients but was manageable, and no severe sequelae of hypertension such as encephalopathy, seizures, or cardiac dysfunction were detected.
Table 4.
Adverse events
| All Participants | Participants Succeeding in Discontinuing CSA | |||||
|---|---|---|---|---|---|---|
| Group | All | Group | All | |||
| A | B | A | B | |||
| Number of participants | 32 | 17 | 49 | 32 | 12 | 44 |
| Adverse reaction | ||||||
| Yes | 2 | 4 | 6 | 2 | 4 | 6 |
| No | 30 | 13 | 43 | 30 | 8 | 38 |
| Gastrointestinal discomfort | 1 | 2 | 3 | 1 | 2 | 3 |
| Hypertension | 0 | 3 | 3 | 0 | 3 | 3 |
| Osteoporosis | 0 | 2 | 2 | 0 | 2 | 2 |
| Cataract | 0 | 1 | 1 | 0 | 1 | 1 |
| Obesity | 1 | 0 | 1 | 1 | 0 | 1 |
| Adrenal suppression | 0 | 1 | 1 | 0 | 1 | 1 |
CSA, cyclosporine.
Discussion
In this follow-up study of patients who had completed 2-year protocol treatment with cyclosporine for the treatment of FRNS, we found that the relapse rate was high, with approximately 60% of patients regressing to FRNS within 2 years of cessation. Risk of relapse of nephrotic syndrome and regression to FRNS were higher in those who had experienced relapse during the 2-year treatment with cyclosporine. These findings indicate that patients experiencing relapse of nephrotic syndrome during treatment with cyclosporine are at high risk of relapse after discontinuation of the drug. To our knowledge, this is the first prospective study to identify the risk of relapse in children with nephrotic syndrome treated with cyclosporine.
The effectiveness and limitations of cyclosporine in children with FRNS have been reported. Several regimens have been tried, which differed with regard to target blood cyclosporine concentration and duration of administration (5–8,19), and although these showed certain efficacy for controlling relapse with varying degrees of adverse events, including nephrotoxicity, these studies did not provide definitive information on treatment dosage or duration. To better define the optimal dosage and duration of treatment with cyclosporine, we conducted a randomized controlled trial with cyclosporine (Sandimmune; Novartis, Basel, Switzerland) (1), followed by a prospective multicenter trial with microemulsified cyclosporine (Neoral) (2), on which the present follow-up study was based. These two trials helped establish that 2-year treatment with cyclosporine under trough control is effective and safe in children with FRNS. Nevertheless, the frequent relapse seen in patients after the cessation of cyclosporine remained of concern.
In this study, most children with FRNS experienced relapse within a few months after the 2-year protocol treatment with cyclosporine was discontinued. These findings strongly suggest that the current 2-year administration period for cyclosporine in the long-term management of children with FRNS is insufficient. The 2-year period was originally established on the basis of previous findings of an increased risk of nephrotoxicity when administration was extended beyond 2 years (20). However, our more recent prospective finding that only 5 of 58 children experienced biopsy-proven nephrotoxicity (mostly mild arteriolar hyalinosis and mild interstitial fibrosis) indicates the good safety of cyclosporine for 2 years (2). In addition, the present high prevalence of relapse after complete discontinuation indicates that the initial treatment period may be extended beyond 2 years, with consideration to the advisability of repeated renal biopsy at 2- to 3-year intervals (9) and relatively lower doses of cyclosporine (8).
Risk factors for relapse after the complete discontinuation of cyclosporine were also evaluated. Comparison of relapse-free survival between those who did (group B) and did not (group A) relapse during the 2-year treatment showed a significantly greater risk in those who did relapse. Similarly, group B had a significantly greater risk of regression to FRNS than group A. These results indicate that the experience of relapse during cyclosporine treatment predicts the course after its discontinuation. Furthermore, they may also suggest the necessity of extending the cyclosporine treatment period beyond 2 years, or a change in immunosuppressive therapy after 2-year treatment with cyclosporine.
We also analyzed other factors with a possible association with relapse, namely age at the beginning of observation and steroid dependency before treatment with cyclosporine. Contrary to our expectation and the results of previous reports (13,14,16), age at the beginning of observation was not significantly associated with either relapse or the regression of FRNS. Similarly, nonsignificant results were also obtained using age at the onset of nephrotic syndrome instead of age at the beginning of observation (data not shown). Moreover, steroid dependency was not a risk factor for relapse or regression to FRNS. The trend is nevertheless consistent with our previous finding that relapse during cyclosporine treatment was unrelated to steroid dependence (2). To note, however, four of five children who were excluded from analysis due to relapse during tapering were steroid dependent; inclusion of these children would have strengthened the association between steroid dependency and risk. In six patients (three each in group A and B), mizoribine, an agent in the same antimetabolite class as mycophenolate mofetil whose efficacy is mild and limited to patients aged ≤10 years (21), was administered during follow-up to prevent regression to FRNS (data not shown). On inclusion in Poisson analyses, administration of mizoribine was positively associated with relapse. Administration was at the discretion of the physician in charge and may have been administered early in those at risk of relapse.
Consistent with a previous report (15), the life expectancy and renal prognosis of our patients were excellent, supporting cyclosporine’s role as first-line treatment in children with FRNS. No lethal events occurred during the approximately 4 years from the beginning of cyclosporine treatment in any participant, and only one patient developed a very mild decrease in renal function. Growth in terms of height was also maintained or slightly improved during the 4 years in spite of relapses and the administration of prednisolone. Other adverse events attributable to corticosteroids and immunosuppressants were also acceptable. This may have been partly due to our prednisolone protocol for relapse, which moves relatively quickly from daily administration to administration every second day.
FRNS has been shown to be a chronic condition (22,23) which requires a long-term strategy with several immunosuppressants and prednisolone (24). Whereas the efficacy of cyclosporine remains clear, we speculate that in addition to prolonged or repeated administration of cyclosporine, the combination of several immunosuppressants given in sequence should also be considered. Recent attention has focused on the efficacy of several emerging immunosuppressants, including tacrolimus (24,25) and rituximab (24,26), in controlling relapse, and both are now under evaluation in children with FRNS in a multicenter, prospective, randomized fashion in Japan. In addition to the control of relapse, long-term management must also consider any adverse effects of therapy as well as the growth and quality of life of children.
Several strengths of this study warrant mention. First, the study is the first multicenter, prospective trial to evaluate the clinical course of children with FRNS after the discontinuation of cyclosporine. Second, the number of participants was relatively large. Several limitations also warrant mention. First, although protocols for the administration of immunosuppressants and prednisolone after treatment with cyclosporine were provided, treatment was at the discretion of the physician in charge. Immunosuppressants were occasionally started before criteria for the diagnosis of FRNS or SDNS had been met, and mizoribine to prevent relapse was sometimes started very early, even before the first relapse, owing to its low incidence of adverse events (21). Second, several data points were missing, including some measurements of height and serum creatinine, particularly among stable children. Third, because of the small sample size, several factors potentially associated with relapse were not examined in Poisson regression analysis. Fourth, five patients in group B who failed in tapering were excluded from analysis. Findings for group B would have been worse if these cases had been included.
In conclusion, we found that children with FRNS who received cyclosporine were at high risk of relapse after its discontinuation. This effect was particularly large in those who experienced relapse during cyclosporine treatment. Given that overall prognosis in terms of life expectancy and renal survival in these children was excellent, long-term strategies should be formulated in consideration of not only relapse, but also adverse effects of treatment, as well as growth and quality of life.
Disclosures
N.Y. has received research grants from Novartis, Japan.
Acknowledgments
The authors thank Drs. Y. Akioka (Tokyo), M. Awazu (Tokyo), A. Furuse (Kumamoto), S. Fujinaga (Saitama), M. Goto (Tokyo), R. Hamada (Tokyo), K. Hamahira (Hyogo), Y. Hamasaki (Tokyo), T. Harada (Kanagawa), K. Hatae (Fukuoka), H. Hataya (Tokyo), M. Hattori (Tokyo), S. Hattori (Kumamoto), M. Hiramatsu (Oita), T. Igarashi (Tokyo), M. Ikeda (Tokyo), S. Kagami (Tokushima), Y. Kaku (Fukuoka), K. Kamei (Tokyo), S. Kodama (Kagoshima), T. Konomoto (Miyazaki), Y. Mishuku (Kanagawa), N. Nakanishi (Osaka), F. Niimura (Kanagawa), K. Nozu (Hyogo), R. Ochiai (Tokyo), Y. Otsuka (Saga), Y. Owada (Tochigi), M. Sako (Tokyo), T. Sato (Saga), H. So (Kagoshima), R. Tanaka (Hyogo), Y. Tanaka (Saitama), H. Wakaki (Tokyo), and K. Yoshidome (Kagoshima) of the Japanese Study Group of Renal Disease in Children for their contributions to this study.
This study was supported in part by the Kidney Foundation, Japan.
The results presented in this article have not been published previously in whole or part, except in abstract form at the 42nd Annual Meeting of the American Society of Nephrology, October 27–November 1, 2009, in San Diego, California.
Footnotes
Published online ahead of print. Publication date available at www.cjasn.org.
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