Atrasentan in Patients With IgA Nephropathy

Approximately 320 patients with biopsy-proven IgAN will be randomized to receive 0.75 mg atrasentan or placebo daily for 132 weeks. Subjects receive a 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. An exception will be made for subjects who are unable to tolerate RAS inhibitor therapy. Additional subjects receiving a stable dose of SGLT2i will be enrolled to the study. Enrollment in this SGLT2i stable stratum will be in accordance with local regulations in regions that prescribe SGLT2i and will be independent of the 320 subjects enrolled for the primary and secondary analyses. The primary objective of the study is to evaluate the effect of atrasentan versus placebo on proteinuria as measured by UPCR. Secondary and tertiary objectives include evaluating the change in kidney function over time as measured by eGFR, safety and tolerability. Subjects will have assessments of safety and efficacy over 2 ½ years. To facilitate study participation over this time period, where allowed by local regulations, options for remote study visits using telemedicine and home health may be offered. Subjects who complete treatment through Week 132 and complete the double-blinded portion of the study may be eligible to enroll in the open label (OL) extension of the study to receive atrasentan 0.75 mg daily for up to 48 weeks. Subjects who complete the 48 weeks of atrasentan treatment in OL extension or who are treated with atrasentan long enough to sufficiently determine its efficacy as per clinical judgement of the Principal Investigator may be optionally re-evaluated for eligibility to participate in the substudy if available at their clinical site. Eligible subjects following re-evaluation may enter the co-administration treatment phase, receiving atrasentan 0.75 mg orally once daily plus zigakibart for 48 weeks.