RCT: Atrasentan Reduces Proteinuria in Patients with IgA Nephropathy
3 Nov, 2024 | 18:29h | UTCBackground: IgA nephropathy is the most common primary glomerular disease worldwide, leading to a substantial risk of kidney failure. Despite treatment with renin–angiotensin system (RAS) inhibitors, many patients experience persistent proteinuria and progressive kidney function decline. Endothelin-1, acting via the endothelin type A receptor, contributes to the disease’s pathophysiology. Atrasentan, a selective endothelin type A receptor antagonist, has shown potential in reducing proteinuria in prior studies.
Objective: To evaluate the efficacy and safety of atrasentan in reducing proteinuria among patients with IgA nephropathy.
Methods: In this phase 3, multinational, double-blind, randomized controlled trial, adults with biopsy-proven IgA nephropathy, urinary protein excretion of at least 1 g/day, and an estimated glomerular filtration rate (eGFR) of at least 30 ml/min/1.73 m² were enrolled. Patients on maximum tolerated doses of ACE inhibitors or ARBs were randomized 1:1 to receive atrasentan (0.75 mg/day) or placebo for 132 weeks. The primary outcome was the change in the 24-hour urinary protein-to-creatinine ratio from baseline to week 36, assessed in a prespecified interim analysis of the first 270 patients.
Results: Among these patients (135 per group), the geometric mean percentage reduction in the urinary protein-to-creatinine ratio at week 36 was significantly greater with atrasentan (−38.1%) compared to placebo (−3.1%), yielding a between-group difference of −36.1 percentage points (95% CI, −44.6 to −26.4; P<0.001). Adverse events were similar between groups. Fluid retention was reported in 11.2% of the atrasentan group and 8.2% of the placebo group but did not lead to discontinuation. No cases of cardiac failure or severe edema occurred.
Conclusions: Atrasentan significantly reduced proteinuria compared to placebo in patients with IgA nephropathy without significant safety concerns.
Implications for Practice: Atrasentan may serve as an effective additional therapy for patients with IgA nephropathy who remain at high risk of progression despite standard care, potentially influencing clinical decision-making toward more aggressive proteinuria reduction strategies.
Study Strengths and Limitations: Strengths include the randomized controlled design and a representative high-risk population. Limitations involve the interim analysis nature of the data and underrepresentation of Black patients, which may limit generalizability.
Future Research: Long-term effects on eGFR decline and the potential benefits of combining atrasentan with other therapies, such as SGLT2 inhibitors, warrant further investigation.