This is a single centre, open-label, single-group study to explore the safety of, and response to sparsentan treatment in incident, renin angiotensin system (RAS) blockade-naïve patients with biopsy-proven immunoglobulin A nephropathy (IgAN). The purpose is to explore sparsentan treatment as a potential first-line treatment in patients newly diagnosed with IgAN (ie, incident patients), who have thus not received prior treatment with ACEI or ARB therapy for IgAN. Response to treatment will be assessed as changes from baseline rather than comparison to another treatment, and will be based on established proteinuria endpoints (UPCR and protein excretion), and glomerular filtration rate (GFR); a number of exploratory measures will be assessed as well.~The starting dose of sparsentan will be 200 mg/day, which will be titrated up to the target dose of 400 mg/day at Week 2. Patients who do not tolerate the target dose will have their dose reduced back to 200 or 100 mg/day; throughout the study, patients will be maintained on the maximum allowed dose of sparsentan they can tolerate. All patients will be treated with sparsentan for a total of 110 weeks, followed by an off-treatment follow-up period of 4 weeks.
To determine the nephroprotective potential of treatment with sparsentan in patients newly-diagnosed with immunoglobulin A nephropathy (IgAN) (ie, incident patients) who have not received prior angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) therapy.