A Study of the Efficacy and Safety of Zigakibart + Atrasentan in Adult Patients With Primary IgA Nephropathy

This is a Phase IIIb, multicenter, two-arm, randomized, double-blind, parallel group study to evaluate the efficacy and safety of zigakibart + atrasentan compared to zigakibart + placebo in patients with primary IgAN at risk of disease progression.

Inclusion Criteria: * Aged ≥ 18 years at the time of signing the informed consent, prior to initiation of any study specific activities/procedures * Biopsy-proven IgAN diagnosed within the past 10 years prior to Screening, that, in the opinion of the Investigator, is not due to secondary causes. If a biopsy report within 10 years is not available, re-biopsy may be performed locally during Screening. * eGFR ≥ 30 mL/min/1.73m2 by a central laboratory at Screening, calculated using serum creatinine based on the 2021 CKD-EPI equation (Inker et al 2021) * UPCR ≥ 0.7 g/g (700 mg/g), as measured from a 24 hour urine collection by a central laboratory at Screening * Stable on a maximally tolerated dose of ACEi and/or ARB for at least 12 weeks prior to Screening unless intolerant to ACEi and ARB. May also be on a stable and well tolerated dose of SGLT2i, MRA, and/or GLP-1A if stable for at least 12 weeks prior to Screening. Participants are expected to stay on a stable dose of ACEi, ARB, SGLT2i, MRA and/or GLP-1A for the duration of the study. Exclusion Criteria: * Chronic Kidney Disease (CKD), either clinically suspected or based on biopsy, resulting from any condition or another glomerulopathy/podocytopathy other than IgAN * Secondary forms of IgAN as determined by the Investigator, in the setting of systemic disorders, infections, autoimmune disorders or neoplasia * Diagnosis of active IgA vasculitis * Clinical suspicion of IgAN with rapidly progressive glomerulonephritis (RPGN) based on Kidney Disease: Improving Global Outcomes (KDIGO) guidelines (2025) * Current clinical diagnosis of nephrotic syndrome * Known history of heart failure or conditions relating to fluid overload such as pulmonary edema, uncontrolled peripheral edema, pleural effusion, or ascites * Current severe infection requiring antimicrobials, or history of recurrent, severe infections as determined by the Investigator Other protocol-defined inclusion/exclusion criteria may apply