The Selective Endothelin Receptor Antagonist SC0062 in IgA Nephropathy

Key Points Patients with IgA nephropathy and significant proteinuria are at high risk of progressive kidney function loss and kidney failure. We report the results of a clinical trial assessing the selective endothelin receptor antagonist SC0062 for the treatment of IgA nephropathy. SC0062 led to clinically meaningful improvements in proteinuria and did not increase risk of peripheral edema at higher doses. Background Endothelin receptor type A activation contributes to kidney injury in patients with IgA nephropathy. SC0062 is a novel selective endothelin receptor type A antagonist. We report the results of a phase 2 dose-finding trial to characterize the efficacy and safety of SC0062 in patients with IgA nephropathy. Methods We conducted a randomized, placebo-controlled, double-blind, clinical trial in adults with biopsy-proven IgA nephropathy and eGFR ≥30 ml/min per 1.73 m 2 with urinary protein-creatinine ratio (UPCR) ≥0.75 g/g or proteinuria ≥1 g/24 hour despite using maximum tolerated doses of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. Patients were randomized 1:1:1:1 to 24-week treatment with SC0062 5, 10, and 20 mg or matching placebo once daily. The primary efficacy outcome was percent change from baseline in UPCR in 24-hour urine samples after 12 weeks of treatment. Secondary end points included changes in eGFR. Safety outcomes including treatment emerging adverse events and serious adverse events were recorded. Results Overall, 131 patients (mean age 42 years [SD, 11]; mean eGFR 72 ml/min per 1.73 m 2 [SD 24] and median 24-hour UPCR 1.2 g/g [25th–75th percentile, 0.9–1.5 g/g]) were randomized to placebo ( n =34) or SC0062 5 mg ( n =33), 10 mg ( n =32), or 20 mg ( n =32). All SC0062 doses reduced UPCR versus placebo throughout treatment. At week 12, placebo-corrected geometric mean changes (95% confidence interval) from baseline in UPCR with SC0062 5, 10, and 20 mg were−27.6% (−43.0 to −8.2), −20.5% (−37.4 to 1.0), and −38.1% (−51.4 to −21.0), respectively, and at week 24 they were−22.4% (−42.2 to 4.3), −30.9% (−48.6 to −7.0), and −51.6% (−64.2 to −34.6), respectively. No differences in eGFR were observed among treatment groups. The proportion of participants with treatment emerging adverse events or serious adverse events was balanced among treatment groups. Peripheral edema was reported by 2 (6%), 1 (3%), 1 (3%) participants in the 5, 10, and 20 mg SC0062-treated groups, respectively, compared with 5 (15%) in the placebo group. Conclusions In patients with IgA nephropathy, SC0062 reduced proteinuria and did not increase risk of peripheral edema. Clinical Trial registry name and registration number: A Study to Evaluate the Efficacy and Safety of SC0062 in the Treatment of CKD, NCT05687890.