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Introduction: Minimal change disease in childhood can follow a frequently relapsing or steroid-dependent course in up to 40% of cases. Second-line immunosuppressive medications that are used to manage these patients are associated with significant adverse effects. There is a need for safer alternative treatments for difficult-to-treat nephrotic syndrome. Therefore, we conducted an open-label feasibility study to assess the safety and efficacy of a gluten-free diet as treatment for pediatric patients with difficult-to-treat nephrotic syndrome. As a second aim, we sought to determine if the plasma zonulin concentration can identify those who are more likely to respond to this intervention. Methods: Seventeen patients were placed on a gluten-free diet for 6 months. A positive response was defined as a 50% reduction in the relapse rate compared to the preceding 6 months or the ability to discontinue 1 immunosuppressive drug. Results: Five (29%) participants had a positive response to the dietary intervention. The gluten-free diet was well tolerated with no clinical or laboratory adverse events. Plasma zonulin concentration was elevated in patients who failed to benefit from the gluten-free diet. Discussion/Conclusion: A gluten-free diet may be a useful adjunctive intervention for patients with difficult-to-treat nephrotic syndrome that can be implemented prior to resorting to second-line immunosuppressive therapy. Development of the plasma zonulin level as a biomarker to predict efficacy would facilitate rational use of a gluten-free diet in the management of nephrotic syndrome.
RESUMO
BACKGROUND: We evaluated and compared the effects of sparsentan, a dual endothelin type A (ETA) and angiotensin II type 1 receptor antagonist, with those of the angiotensin II type 1 receptor antagonist irbesartan in patients with primary FSGS. METHODS: In this phase 2, randomized, double-blind, active-control Efficacy and Safety of Sparsentan (RE-021), a Dual Endothelin Receptor and Angiotensin Receptor Blocker, in Patients with Focal Segmental Glomerulosclerosis (FSGS): A Randomized, Double-blind, Active-Control, Dose-Escalation Study (DUET), patients aged 8-75 years with biopsy-proven FSGS, eGFR>30 ml/min per 1.73 m2, and urinary protein-to-creatinine ratio (UP/C) ≥1.0 g/g received sparsentan (200, 400, or 800 mg/d) or irbesartan (300 mg/d) for 8 weeks, followed by open-label sparsentan only. End points at week 8 were reduction from baseline in UP/C (primary) and proportion of patients achieving FSGS partial remission end point (FPRE) (UP/C: ≤1.5 g/g and >40% reduction [secondary]). RESULTS: Of 109 patients randomized, 96 received study drugs and had baseline and week 8 UP/C measurements. Sparsentan-treated patients had greater reductions in UP/C than irbesartan-treated patients did when all doses (45% versus 19%; P=0.006) or the 400 and 800 mg doses (47% versus 19%; P=0.01) were pooled for analysis. The FSGS partial remission end point was achieved in 28% of sparsentan-treated and 9% of irbesartan-treated patients (P=0.04). After 8 weeks of treatment, BP was reduced with sparsentan but not irbesartan, and eGFR was stable with both treatments. Overall, the incidence of adverse events was similar between groups. Hypotension and edema were more common among sparsentan-treated patients but did not result in study withdrawals. CONCLUSIONS: Patients with FSGS achieved significantly greater reductions in proteinuria after 8 weeks of sparsentan versus irbesartan. Sparsentan was safe and well tolerated.