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

Clinical applicability of 2023 International Pediatric Nephrology Association recommended limited therapeutic drug monitoring formulae to assess mycophenolic acid exposure

BACKGROUND

The 2023 IPNA guidelines recommended a 12-h mycophenolic acid (MPA) area under the curve (AUC) estimation for managing pediatric nephrotic syndrome and MPA AUC > 50 mg * h/L for an optimal therapeutic response to mycophenolate mofetil (MMF). The IPNA guidelines endorsed two limited AUC formulae based on three-point MPA measurements to predict 12-h MPA AUC. The relative performance of these two limited AUC formulae has not been tested.

METHODS

We analyzed 156 MPA AUCs from 122 stable kidney transplant recipients to predict the 12-h AUC (10 MPA measurements analyzed with trapezoid rule) using the IPNA-recommended three-point Formula 1 and Formula 2.

RESULTS

Three-point Formula 1 and Formula 2 classified 69% and 60% limited MPA AUCs as > 50 mg * h/L (difference 8.90%, p = 0.10). Three-point Formula 1 and Formula 2 demonstrated a similar association with 12-h AUC (R2 0.72 vs. 0.71) and exhibited identical areas under ROC (AUROC) for predicting 12-h AUC > 50 mg * h/L (AUROC 0.82, 95% CI 0.75, 0.88 vs. 0.80, 95% CI 0.73, 0.86; p = 0.53). Fixed MMF dose and MPA C0 level showed a relatively weaker association (R2 0.16 and 0.43) with 12-h AUC. Four-point MPA formulae improved the prediction of 12-h AUC compared to the three-point formulae. Among all C0 thresholds, C0 > 3.5 mg/L demonstrated the best prediction of 12-h AUC > 50 mg * h/L (AUROC 0.74, 95% CI 0.66, 0.80).

CONCLUSIONS

IPNA recommended limited AUC formulae perform equivalently and improve upon MMF dose and C0 level to predict 12-h MPA AUC.

Tacrolimus or Mycophenolate Mofetil for Frequently Relapsing or Steroid-Dependent Nephrotic Syndrome: A Randomized Clinical Trial

Importance

Both tacrolimus (TAC) and mycophenolate mofetil (MMF) are recommended for children with frequently relapsing nephrotic syndrome (FRNS) or steroid-dependent nephrotic syndrome (SDNS). However, their comparative effectiveness and safety have not been evaluated through randomized clinical trials.

Objective

To compare the effectiveness and safety of TAC and MMF in children with FRNS or SDNS.

Design, Setting, and Participants

In this multicenter, open-label randomized clinical trial conducted at 12 pediatric nephrology centers across China, 270 children aged 2 to 18 years with FRNS or SDNS were allocated at a 1:1 ratio to treatment with either TAC or MMF. The study was conducted from November 2019 to July 2023, and data analysis was completed from July 2023 to March 2024.

Intervention

Patients received either TAC (0.025-0.050 mg/kg, orally twice daily) or MMF (10-15 mg/kg, orally twice daily) for 1 year, along with a tapering regimen of steroids.

Main Outcomes and Measures

The primary end point was 1-year relapse-free survival. Relapse frequency, cumulative steroid dosage, and safety profiles were also evaluated.

Results

A total of 292 patients from 12 care centers were assessed for eligibility, and 270 patients were randomized to receive either TAC (n = 135) or MMF (n = 135). Among 270 patients, median (IQR) age was 6.91 (4.25-9.96) years, and 70 patients (25.9%) were female. Compared with MMF, the 1-year relapse-free survival rate in the TAC group was 1.86-fold higher (hazard ratio [HR], 2.86; 95% CI, 1.79-4.76; P < .001) in the intention-to-treat analysis. This difference was also significant after adjusting for the per-protocol analysis (HR, 2.78; 95% CI, 1.72-4.55; P < .001). The mean (SD) time to first relapse was significantly longer in the TAC group (323.99 [98.33] days) compared to the MMF group (263.21 [132.84] days). Furthermore, the TAC group showed a lower annual relapse rate than the MMF group (17.78% vs 41.48%) and required a significantly lower mean (SD) cumulative steroid dose (0.22 [0.10] mg/kg/day vs 0.34 [0.22] mg/kg/day). The safety profile was similar in both groups.

Conclusions and Relevance

In this randomized clinical trial, compared with MMF, a 1-year course of TAC therapy significantly extended the period of relapse-free survival in children with FRNS or SDNS.

Trial Registration

ClinicalTrials.gov Identifier: NCT04048161.

Minimal Change Disease

Minimal change disease represents a common cause of nephrotic syndrome in both pediatric and adult patients. Although much remains to be discovered, there have been significant recent advancements in our understanding of the pathophysiology of minimal change disease, including the discovery of antinephrin antibodies as a marker for diagnosis of disease. Here we will review what is known about the pathophysiology, treatment, and prognosis of minimal change disease and the differences between pediatric and adult patients. Recent advances in our understanding of the mechanisms of disease will be noted. We will discuss how this may change the treatment of minimal change disease going forward and what remains to be studied.

Immunosuppressive agents for frequently relapsing/steroid-dependent nephrotic syndrome in children: a systematic review and network meta-analysis

Aim

This study aimed to systematically compare the efficacy of various immunosuppressive agents in treating pediatric frequently relapsing or steroid-dependent nephrotic syndrome (FRSDNS).

Methods

We conducted systematic searches of PubMed, Embase, the Cochrane Library, and the Web of Science up to May 23, 2023. Outcome measures included relapses within 1 year, mean cumulative exposure to corticosteroids, patients with treatment failure at 1 year, relapse-free survival during 1 year, and adverse events. The quality of the included studies was evaluated using the modified Jadad scale, the Methodological Index for Non-Randomized Studies (MINORS), and the modified Newcastle-Ottawa Scale (NOS).

Results

Rituximab was found to be the most likely (92.44%) to be associated with the fewest relapses within 1 year and was also most likely (99.99%) to result in the lowest mean cumulative exposure to corticosteroids. Rituximab had the highest likelihood (45.98%) of being associated with the smallest number of patients experiencing treatment failure at 1 year. CsA was most likely (57.93%) to achieve the highest relapse-free survival during 1 year, followed by tacrolimus (26.47%) and rituximab (30.48%). Rituximab showed no association with serious side effects and had comparable adverse effects to ofatumumab and tacrolimus.

Conclusion

Rituximab may be the most favorable immunosuppressive agent for treating pediatric FRSDNS. Nephrologists should consider this drug, along with their clinical experience, patient characteristics, and cost considerations, when choosing a treatment approach.

Therapeutic drug monitoring in childhood idiopathic nephrotic syndrome: a state of the art review

Immunosuppressants are commonly used as steroid-sparing agents in childhood idiopathic nephrotic syndrome (NS) to induce and sustain remissions. These drugs have narrow therapeutic indices with high inter- and intra-patient variability. Therapeutic drug monitoring (TDM) would therefore be essential to guide the prescription. Multiple factors in NS contribute to additional variability in drug concentrations, especially during relapses. In this article, we review the currently available evidence of TDM in NS and suggest a practical approach for clinicians' reference.

Childhood nephrotic syndrome

Idiopathic nephrotic syndrome is the most common glomerular disease in children. Corticosteroids are the cornerstone of its treatment, and steroid response is the main prognostic factor. Most children respond to a cycle of oral steroids, and are defined as having steroid-sensitive nephrotic syndrome. Among the children who do not respond, defined as having steroid-resistant nephrotic syndrome, most respond to second-line immunosuppression, mainly with calcineurin inhibitors, and children in whom a response is not observed are described as multidrug resistant. The pathophysiology of nephrotic syndrome remains elusive. In cases of immune-mediated origin, dysregulation of immune cells and production of circulating factors that damage the glomerular filtration barrier have been described. Conversely, up to a third of cases of steroid-resistant nephrotic syndrome have a monogenic origin. Multidrug resistant nephrotic syndrome often leads to kidney failure and can cause relapse after kidney transplant. Although steroid-sensitive nephrotic syndrome does not affect renal function, most children with steroid-sensitive nephrotic syndrome have a relapsing course that requires repeated steroid cycles with significant side-effects. To minimise morbidity, some patients require steroid-sparing immunosuppressive agents, including levamisole, mycophenolate mofetil, calcineurin inhibitors, anti-CD20 monoclonal antibodies, and cyclophosphamide. Close monitoring and preventive measures are warranted at onset and during relapse to prevent acute complications (eg, hypovolaemia, acute kidney injury, infections, and thrombosis), whereas long-term management requires minimising treatment-related side-effects. A subset of patients have active disease into adulthood.

Mycophenolate Mofetil in the Treatment of Steroid-Dependent or Frequently Relapsing Nephrotic Syndrome in Children: A Meta-Analysis

Objectives: This meta-analysis aims to evaluate the efficacy and safety of the mycophenolate mofetil (MMF) in the treatment of steroid-dependent nephrotic syndrome (SDNS) or frequently relapsing nephrotic syndrome (FRNS) in children. Methods: We searched for the studies especially the randomized controlled trials in PubMed, Cochrane Library, Embase, China National Knowledge Infrastructure, and Wan Fang database. The data were analyzed by Review Manager 5.3 software. We used the GRADE pro-Guideline Development Tool online software to evaluate the quality of evidence. Results: Finally, we identified 620 studies, of which we included five randomized controlled trials and one prospective cohort study with 447 children. The results showed the following: (1) the relapse-free survival rate within 1 year-the MMF group was superior to the levamisole group [ratio difference (RD) = 0.13, 95% CI (0.02, 0.24), P = 0.02] but not to the calcineurin inhibitors (CNIs) group [RD = -0.27, 95%CI (-0.40, -0.14), P < 0.0001]; (2) the number of relapses within 1 year-the MMF group was less than that in the CNIs and levamisole group [mean difference (MD) = -0.26, 95%CI (-0.45, -0.08), P = 0.005]; (3) the cumulative prednisone dosage-the MMF group was lower than that in the control group [standardized mean difference (SMD) = -0.32, 95%CI (-0.53, -0.11), P = 0.003]; (4) incidence of adverse reactions-there was no significant difference between the MMF group and the control group [RD = 0.02, 95%CI (-0.04, 0.09), P = 0.46]. Conclusion: The therapy of mycophenolate mofetil in the treatment of SDNS or FRNS in children has a certain advantage in reducing the number of relapses and cumulative prednisone dosage within 1 year when compared with the CNIs and levamisole. However, due to the limited quantity and quality of the included studies, the conclusions above need to be confirmed by more high-quality randomized controlled trials.

Tacrolimus treatment in childhood refractory nephrotic syndrome: A retrospective study on efficacy, therapeutic drug monitoring, and contributing factors to variable blood tacrolimus levels

Tacrolimus, an immunosuppressive drug, was recommended by the 2012 KDIGO guidelines to treat nephrotic syndrome (NS) in children and adults. However, it has high interpatient pharmacokinetic variability and exposure levels should be monitored, although there are no specified target concentrations. This retrospective study aimed to review efficacy and safety after concomitant treatment with tacrolimus and prednisone, and to identify factors that contribute to the variable blood-trough-concentration-to-dose (C₀/Dose) ratio in children with refractory NS (RNS). A 6-month therapy induced complete or partial remission in 95% of patients. One-year follow-up indicated a high remission rate and low nephrotoxicity. Under maintenance dosages, approximately 95% of the C₀ values were 2-7 ng/mL. Body weight (BW), age, CYP3A5 polymorphisms were the factors affecting the C₀/Dose ratio. The C₀/Dose ratio in patients with a BW of <20 kg was 1.5-fold than that in patients with BW of ≥40 kg. Moreover, the C₀/Dose ratio in patients aged 1-≤6 and 6-≤12 years was significantly lower than that in patients aged 12-≤18 years, by 25% and 48%, respectively. There were no significant association between CYP3A5 genotyping and C₀/Dose ratio in younger children (1-≤6 years), rather than older children (6-≤18 years). In conclusion, routine CYP3A5 genotyping should be considered in children aged over 6 years and exposure levels (C₀) of 2-7 ng/mL may be feasible when tacrolimus is combined with low-dose prednisone to treat childhood RNS.

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.

Mycophenolate mofetil for sustained remission in nephrotic syndrome

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

[Treatments of steroid-dependent nephrotic syndrome in children]

Primary nephrotic syndrome (NS) is the most common glomerular disease in children. It is characterized by massive proteinuria and hypoalbuminemia. It typically has a sudden onset and more than 70% of patients will experience at least one relapse. An immunological origin has long been postulated, although the precise molecular mechanisms underlying the disease remain debated. Steroids are the first-line therapy with cumulative dose and duration of initial treatment varying among countries. Steroid-sparing agents may be indicated in case of steroid-dependency or frequent relapses. However, no consensus exists regarding the different treatment options. These treatments are mostly suspensive and therefore, need to be prolonged for several months. Levamisole, an antihelminthic drug, also has an immunomodulatory function, and alone or in combination with steroids, it can decrease cumulative steroid dose and relapses. It is usually well tolerated, and its principal side effects are cytopenia and elevated liver enzymes. Mycophenolate mofetil is an immunosuppressive agent whose reported side effects are cytopenia and diarrhea. Calcineurin inhibitors (cyclosporine or tacrolimus) have long been used in steroid-dependent patients. Their major side effects are hirsutism, gum hypertrophy, and nephrotoxicity, leading to interstitial kidney fibrosis and chronic kidney disease. Cyclophosphamide is an efficient treatment but its gonadal toxicity is a major drawback to its use. More recent drugs such as rituximab are very effective but require hospitalization for the infusion and induce an increased risk of opportunistic infection, prolonged neutropenia, and anaphylaxis. In this review, we present the available treatments, their indications, and the side effects.