Jingjing Wang, Fei Liu, Weili Yan, Jianhua Zhou, Yu Zhang, Liping Rong, Xiaoyun Jiang, Fei Zhao, Chunhua Zhu, Xiaochuan Wu, Xiaoyan Li, Shuzhen Sun, Jing Wang, Mo Wang, Qin Yang, Hong Xu, Jing Chen, Cuihua Liu, Ming Tian, Shipin Feng, Qinwei Duan, Xuhui Zhong, Yun Zhu, Xiaozhong Li, Haidong Fu, Lingfei Huang, Daqing Ma, Jie Ding, Qing Ye, Jianhua Mao
5 min
Children with steroid-sensitive nephrotic syndrome often develop frequently relapsing (FRNS) or steroid-dependent (SDNS) forms of the disease, requiring long-term use of steroid-sparing agents. While both tacrolimus (TAC) and mycophenolate mofetil (MMF) are recommended as first-line treatments, there has been a lack of high-quality, randomized clinical trial evidence to determine which is superior. This multicenter, open-label, parallel-arm randomized clinical trial (the STAMP trial) enrolled 270 children across 12 centers in China to directly compare the efficacy and safety of these two medications over a one-year period.
The study found that tacrolimus was superior to mycophenolate mofetil in maintaining remission. Patients treated with TAC had a 1.86-fold higher 1-year relapse-free survival rate compared to those on MMF. Additionally, the TAC group experienced a significantly lower annual relapse rate (17.78% vs 41.48%) and required a lower cumulative dose of corticosteroids. While both groups showed similar safety profiles regarding adverse events, the TAC group demonstrated a more pronounced decline in estimated glomerular filtration rate (eGFR) slope, raising potential concerns about subclinical nephrotoxicity that require longer-term monitoring.
These findings provide the first large-scale, prospective evidence to guide clinical decision-making for pediatric nephrologists treating FRNS and SDNS. By demonstrating that tacrolimus is more effective at sustaining long-term remission and reducing steroid exposure, the study supports prioritizing TAC in patients who require robust relapse prevention. However, the observed decline in eGFR slope serves as a reminder that clinicians must balance the superior efficacy of calcineurin inhibitors like tacrolimus against the potential for long-term kidney damage, necessitating careful, individualized dosing and ongoing monitoring.
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.
Sam: But twelve months is a limited window for a calcineurin inhibitor.
Alex: Precisely. The authors flag this themselves. There was a trend toward eGFR decline in the tacrolimus group that remained subclinical over the trial period — but subclinical at twelve months doesn't mean irrelevant at five years. Calcineurin inhibitor nephropathy is characteristically insidious. This is the single most important constraint on how much weight the safety finding can bear, and it's the result that most needs a longer follow-up study to resolve.
Sam: What about the trial design itself — where would a careful referee push back?
Alex: The open-label design is the main methodological vulnerability. Allocation concealment was rigorous, so the randomization is sound. But without masking, clinician judgment about whether a child is in early relapse — which is often a borderline call — could be influenced by treatment assignment. If clinicians managing tacrolimus patients are slightly more inclined to treat ambiguous symptoms as remission rather than relapse, that would inflate the apparent efficacy advantage. It's not a fatal flaw, but it does mean the effect size should be interpreted with some caution.
Sam: And the generalizability question — this was conducted entirely in China, which matters for a disease where genetic background and environmental factors may shape the phenotype.
Alex: That's a real constraint. The distribution of podocin and nephrin variants, the background infection burden that can trigger relapses — these could differ in ways that affect which agent performs better. The finding is internally valid, but extrapolating it as a universal standard of care requires replication in more diverse cohorts.
Sam: So where does this leave the field? Is tacrolimus now the first-line steroid-sparing agent for this population?
Alex: The data support moving it up the hierarchy. For a clinician managing a child with frequent relapses and significant steroid toxicity, this trial gives you the evidence to prefer tacrolimus over MMF as your initial steroid-sparing choice. But it doesn't close the conversation. The pharmacogenomics question is largely unaddressed — there are almost certainly MMF-responders in this population, and identifying them prospectively would be a meaningful step toward personalized management. And the long-term renal safety data simply isn't there yet.
Sam: So the practical takeaway is: tacrolimus is the more effective tool for preventing relapses in the short term, but it comes with an obligation for vigilant monitoring and a genuine need for longer follow-up before we're confident about the renal safety profile.
Alex: That's exactly right. The STAMP trial breaks the equipoise on efficacy — that's a meaningful contribution after years of operating on consensus alone. What it doesn't do is fully resolve the long-term safety question, and that's where the next phase of evidence needs to go. Thanks for listening to ResearchPod.