A study of the effect and safety of sparsentan in the treatment of patients with immunoglobulin A nephropathy.

INTERVENTION: Sparsentan will be administered daily as a 200‐mg oral tablet, over‐encapsulated (blinded) size 00 capsule, for the first 2 weeks of the study following randomization. For patients who tolerate the initial dose of 200 mg and maintain systolic blood pressure >100 mmHg and diastolic blood pressure >60 mmHg after 2 weeks will increase their dose to 400 mg at Week 3 through Week 110. If patients do not tolerate the increase in dose, they can move back down to the initial dose for the duration of the study. Patient's compliance with the treatment will be assessed. Patients will be asked to return all unused study medication at each visit. CONDITION: Immunoglobulin A Nephropathy PRIMARY OUTCOME: Change from baseline in urine protein/creatinine ratio (UP/C) at Week 36 SECONDARY OUTCOME: Number of patients with urinary protein excretion <=0.3 g/day at Week 36. Rate of change in estimated glomerular filtration rate (eGFR) over a 104‐week period following initial acute effect of randomized therapy. Rate of change in estimated glomerular filtration rate (eGFR) over a 52‐week period following initial acute effect of randomized therapy. INCLUSION CRITERIA: • Age 18 years or older at screening • Biopsy‐proven primary IgAN • Proteinuria of >=1 g/day at screening • eGFR >=30 mL/min/1.73 m2 at screening • Currently on stable dose of ACEI and/or ARB therapy for at least 12 weeks prior to screening • Systolic BP <=150 mmHg and diastolic BP <=100 mmHg at screening • Agree to contraception