Atrasentan in Patients With IgA Nephropathy

Inclusion Criteria:

1. Biopsy-proven IgA nephropathy.
2. Receiving a maximally tolerated dose of RAS inhibitor therapy (ACEi or ARB) that has been stable for at least 12 weeks. Exceptions from this requirement will be made for subjects who are unable to tolerate RAS inhibitor therapy.
3. Total urine protein ≥1 g/day as measured via 24-hour urine collection by central laboratory at Screening.
4. eGFR of at least 30 mL/min/1.73 m2 at Screening based on the CKD-EPI equation.
5. Willing and able to provide informed consent and comply with all study requirements.
6. SGLT2i Stable Stratum Only - Receiving a stable dose of an SGLT2i (per Investigator choice) in addition to a maximally tolerated and optimized dose of a RAS inhibitor that has been stable for at least 12 weeks prior to Screening.

Exclusion Criteria:

1. Current diagnosis with another chronic kidney disease, including diabetic kidney disease.
2. History of kidney transplantation or other organ transplantation.
3. Use of systemic immunosuppressant medications, such as steroids, for more than 2 weeks in the past 3 months.
4. Blood pressure above 150 mmHg systolic or 95 mmHg diastolic as evaluated by the Investigator.
5. Known history of heart failure or a previous hospital admission for fluid overload.
6. Clinically significant history of liver disease as assessed by the Investigator.
7. Hemoglobin below 9 g/dL as measured by the Investigator or prior history of blood transfusion for anemia within the past 3 months.
8. Malignancy within the past 5 years. Exceptions to this criteria include nonmelanoma skin cancer and curatively treated cervical carcinoma in situ.
9. For women, pregnancy, breast feeding, or intent to become pregnant during the study. and at least 1 month afterward.
10. For men, intent to father a child or donate sperm during the study.
11. Have received any investigational agent or approved treatment for IgAN (other than a RAS inhibitor) including SGLT2i (except for subjects in the SGLT2i stable stratum) within 1 month (or 5 half-lives of the agent, whichever is longer) prior to Screening. If the investigational agent is a cytotoxic or immunosuppressive agent then this washout period is 6 months.