A Study of the Safety and Activity of Sparsentan for the Treatment of Patients With Immunoglobulin A Nephropathy

For Cohort A (Patients with Incident IgAN) Inclusion Criteria: * The patient is willing and able to provide signed informed consent. * The patient can understand written and spoken English. * The patient is male or female, aged ≥18 years. * The patient has been diagnosed with biopsy-proven IgAN within the last 6 months (calculated from the date of kidney biopsy, upon which the IgAN-positive diagnosis was made, to the signing of the informed consent form). * The patient has a urine total protein value ≥0.5 g/day at screening. * The patient has an eGFR value ≥30 mL/min/1.73 m2 at screening. * The patient has not previously been treated with ACEI and/or ARB therapy for IgAN OR has not received ACEI and/or ARB therapy within the last 12 months. * The patient has a systolic BP ≤150 mmHg and ≥100 mmHg, and diastolic blood pressure ≤100 mmHg and ≥60 mmHg at screening. * Women of childbearing potential (WOCBP), beginning at menarche, must agree to the use of one highly reliable (ie, can achieve a failure rate of \<1% per year) method of contraception from 7 days prior to the first dose of trial medication until 90 days after the last dose of trial medication. Highly reliable contraception methods include stable oral, implanted, transdermal, or injected contraceptive hormones associated with inhibition of ovulation, or an intrauterine device (IUD) in place for at least 3 months. One additional barrier method must also be used during sexual activity, such as a diaphragm or diaphragm …