Trial of Sibeprenlimab in the Treatment of A Nephropathy (IgAN)

This is a multicenter, randomized, double-blind, placebo-controlled study to evaluate the efficacy and safety of sibeprenlimab 400 mg administered SC Q 4 weeks compared to placebo in patients with IgAN. The primary objective is to compare the relative change from baseline in the urinary protein to creatinine ratio (uPCR) in 24-hour urine collections, after 9 months of treatment. The key secondary objective is to compare the annualized rate of change from baseline (slope) of estimated glomerular filtration rate (eGFR) after approximately 24 months of treatment. There will be one main cohort comprised of approximately 450 subjects with source-verified biopsy-confirmed IgAN and eGFR ≥ 30 mL/min/1.73 m\^2. An additional exploratory cohort will be comprised of up to 20 subjects with source-verified biopsy confirmed IgAN and eGFR of 20 to \< 29 mL/min/1.73 m\^2.