Study to Assess the Efficacy, Pharmacokinetics, Safety and Tolerability of Atrasentan in Pediatric Patients With Primary IgAN

This Phase III study aims to address the unmet medical need in pediatric primary IgAN by assessing the efficacy, pharmacokinetics, safety, and tolerability of atrasentan in patients aged 2 to \<18 years. Pediatric patients with biopsy-confirmed IgAN will receive atrasentan (0.75 mg or a body-weight-adjusted dose) for up to 104 weeks while taking the maximally tolerated and stable dose of a RAS (renin-angiotensin system) inhibitor \[such as angiotensin converting enzyme inhibitor (ACEi) or angiotensin-receptor antagonist (ARB)\] as part of standard of care, if possible.

The primary objective of the study is to evaluate the effect of atrasentan in reducing proteinuria from Baseline to Week 36. UPCR will be measured based on the geometric mean of 2 FMVs obtained during the Run-in period and preceding each scheduled visit.

The study will enroll pediatric patients in a staggered approach. The approach will be to first enroll a subset of Cohort 1 (≥40 kg of body weight) patients to collect safety data, tolerability data, PK data and biomarker data for up to 104 weeks (EOS). Confirmatory PK and safety review will be held at multiple timepoints throughout the trial. There is a data monitoring committee (DMC) which will function independently of all other individuals associated with the conduct of this clinical trial, including the site investigators participating in the study. The DMC will assess at defined intervals the progress of a clinical trial, safety data and recommend to the study team whether to continue, modify, or terminate the trial.

Subjects who complete treatment through Week 104 and complete the study may be eligible to enroll in the open label extension of the study to receive atrasentan 0.75 mg or a body-weight adjusted appropriate dose.