A Phase 2 Trial of the Safety and Efficacy of Bardoxolone Methyl in Patients With Rare Chronic Kidney Diseases - PHOENIX

Inclusion Criteria: * Male and female patients 18 ≤ age ≤ 65 upon study consent; * Screening eGFR (average of Screen A and Screen B eGFR values) ≥ 30 and ≤ 90 mL/min/1.73 m2. The two eGFR values collected at Screen A and Screen B visits used to determine eligibility must have a percent difference ≤ 25%; * Albumin to creatinine ratio (ACR) ≤ 2500 mg/g at Screen B visit; * If receiving an angiotensin-converting enzyme (ACE) inhibitor and/or an angiotensin II receptor blocker (ARB), patients should be prescribed the maximally tolerated labeled daily dose (MTLDD) for at least 6 weeks prior to the Screen A visit; * For patients enrolling in T1D Cohort: Diagnosis of type 1 diabetes confirmed by fasting C-peptide level. Diagnosis must have been made ≤ 35 years of age; and prescribed stable dose of insulin to maintain adequate glucose control for at least 6 months prior to the Screen A visit; * For patients enrolling in IgAN Cohort: Biopsy-confirmed IgA nephropathy; * For patients enrolling in FSGS Cohort: Biopsy-confirmed FSGS that is not due to known secondary causes including morbid obesity, decreased renal mass, viral infections, drug-induced nephrotoxicity, or prior history of vasculitis; * For patients enrolling in ADPKD Cohort: Genetic confirmation of PKD1 mutation; * Adequate bone marrow reserve and organ function at the Screen A visit as follows: Hematologic: Absolute neutrophil count \> 1.5 x 109/L, platelets \> 100 x 109/L, hemoglobin (Hgb) ≥ 9 g/dL; and Hepatic: Total bilirubin (TBL) ≤ 1.5 times the upper limit of normal (ULN), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 1.5 times ULN. Exclusion Criteria: * Kidney or any other solid organ transplant recipient or a planned transplant during the study; * B-type natriuretic peptide (BNP) level \> 200 pg/mL at Screen A visit; * Acute dialysis or acute kidney injury within 12 weeks prior to Screen A visit or during Screening; * Serum albumin \< 3 g/dL at Screen A visit; * Systemic immunosuppression for more than 2 weeks, cumulatively, within the 12 weeks prior to randomization or anticipated need for immunosuppression during the study; * For patients enrolling in IgAN Cohort: Systemic manifestations of Henoch-Schonlein purpura within 1 year prior to Screen A visit; or have used belimumab, eculizumab, or rituximab within 6 months prior to Screen A visit; * For patients enrolling in ADPKD Cohort: Receiving tolvaptan; * Cerebrovascular event (stroke, transient ischemic attack) or aneurysm within 6 months prior to Screen A visit or during Screening; * History of clinically significant left-sided heart disease and/or clinically significant cardiac disease; * Uncontrolled systemic hypertension; * Systolic BP \< 90 mm Hg at Screen A visit after a period of rest; * History of malignancy within 2 years prior to Screen A visit, with the exception of localized skin or cervical carcinomas; * Uncontrolled diabetes (HbA1c \> 10.0%) at Screen A visit; * Untreated or uncontrolled active bacterial, fungal, or viral infection; * Participation in other interventional clinical studies within 30 days prior to Day 1; * Unwilling to practice acceptable methods of birth control (both males who have partners of child-bearing potential and females of childbearing potential) during Screening, while taking study drug, and for at least 30 days after the last dose of study drug is ingested; * Women who are pregnant or breastfeeding.