Atrasentan in Patients With Proteinuric Glomerular Diseases

Inclusion Criteria: * Age 18 years and older for patients in the IgAN, FSGS, and Alport Syndrome cohorts * Age 18-70 years for patients in the DKD cohort * Receiving a maximally tolerated dose of RAS inhibitor therapy (ACEi or ARB) that has been stable for at least 12 weeks. * For patients enrolling in IgAN Cohort: 1. Biopsy-proven IgA nephropathy 2. UPCR between 0.5 to less than 1.0 g/g 3. Screening eGFR ≥ 30 mL/min/1.73 m2 * For patients enrolling in FSGS Cohort: 1. Biopsy-proven FSGS or documented genetic mutation in a podocyte protein associated with FSGS 2. UPCR \> 1.0 g/g 3. Screening eGFR ≥ 30 mL/min/1.73 m2 4. Subjects receiving systemic corticosteroids or other immunosuppressants must be on a stable dose for at least 12 weeks. 5. BMI ≤ 40 kg/m2 * For patients enrolling in Alport syndrome Cohort: 1. Diagnosis of Alport syndrome by genetic testing 2. UPCR \> 0.5 g/g 3. Screening eGFR ≥ 30 mL/min/1.73 m2 * For patients enrolling in DKD Cohort: 1. Diagnosis of type 2 diabetes mellitus 2. UACR ≥ 0.5 g/g 3. Screening eGFR ≥ 45 mL/min/1.73 m2 4. Receiving a stable dose of SGLT2 inhibitor for at least 12 weeks * Willing and able to provide informed consent and comply with all study requirements Exclusion Criteria: * Current diagnosis of another cause of chronic kidney disease or another primary glomerulopathy. * History of kidney transplantation or other organ transplantation. * Except for FSGS patients, use of systemic immunosuppressant medications, such as steroids, for more than 2 weeks in the past 3 months. * Blood pressure above 150 mmHg systolic or 95 mmHg diastolic as evaluated by the Investigator. * History of heart failure or a previous hospital admission for fluid overload. * Clinically significant history of liver disease as assessed by the Investigator. * Hemoglobin below 9 g/dL as measured by the Investigator or blood transfusion for anemia within the past 3 months. * Clinical diagnosis of nephrotic syndrome * Malignancy within the past 5 years. Exception to the criteria include nonmelanoma skin cancer and curatively treated cervical carcinoma in situ. * For women, pregnant, breastfeeding, or intent to become pregnant during the study. * For men, intent to father a child or donate sperm during the study. * Recently received an investigational agent. * Clinically significant unstable or uncontrolled medical condition as assessed by the Investigator.