Chinook Therapeutics U.S., Inc.

Compare the efficacy and safety of Atrasentan versus placebo in IgAN subjects at risk of progressive renal function loss; Primary assessment of the effect of Atrasentan versus placebo on proteinuria levels at Week 24; Secondary assessments to evaluate the effect of Atrasentan versus placebo on the change in estimated glomerular filtration rate (eGFR) from baseline to Week 136 (4 weeks after cessation of randomized treatment); Compare the 2-year treatment change rate of eGFR between Atrasentan and placebo (eGFR slope from Week 12 of randomized treatment to Week 120); Compare the overall study change rate of eGFR between Atrasentan and placebo (eGFR slope from baseline to Week 136) and determine the safety and tolerability profile of Atrasentan compared to placebo. Exploratory assessment of the quality of life (QOL) of subjects receiving Atrasentan compared to placebo; Steady-state pharmacokinetics (PK) of Atrasentan to support exploratory exposure-response analysis; Assess changes in disease biomarkers and other safety outcomes.