A Study of the Effect and Safety of Sparsentan in the Treatment of Patients With IgA Nephropathy

This is a 114-week,randomized, multicenter, double-blind, parallel-group, active-control study with an open-label extension period of up to 156 weeks, for a total duration of up to 270 weeks in patients with IgAN who have persistent overt proteinuria and remain at high risk of disease progression despite being on a stable dose (or doses) of an angiotensin-converting enzyme inhibitor (ACEI) and/or angiotensin receptor blocker (ARB) that is (are) a maximum tolerated dose that is at least one half of the maximum labeled dose (MLD) (according to approved labeling. Approximately 380 patients aged ≥18 years will be enrolled in the study globally. The investigational drug (sparsentan) is a dual acting angiotensin receptor blocker and endothelin receptor antagonist. The active control is irbesartan. The purpose of the study is to evaluate the potential benefit of sparsentan on kidney function by analyzing change in proteinuria (protein in urine) and estimated glomerular filtration rate (eGFR) as compared to current standard treatment. Patients enrolled in the PROTECT study (Protocol 021IGAN17001) will be those at high risk of progressing to renal failure. They will be randomly assigned in a 1:1 ratio to either sparsentan or irbesartan, as the active control (current standard treatment) at the Day 1 (Randomization) visit. Study medication (sparsentan and irbesartan) will be administered as a single oral morning dose. The primary analysis is change in proteinuria (urine protein/creatinine ratio) from baseline at Week 36 in sparsentan-treated patients as compared to irbesartan-treated patients. Primary completion date represents the anticipated completion date of the double-blind portion of the study. Study completion date represents the anticipated completion date of the open-label extension portion of the study. Patients participating in the open-label extension period may be evaluated for eligibility to participate in a randomized, open-label, controlled Sub study evaluating the safety and efficacy of an SGLT2 inhibitor in addition to stable sparsentan treatment (OLE Sub study). The SGLT2 inhibitor, dapagliflozin will be provided as "study medication" for the OLE Sub study. Following completion of the visit 12 weeks after the OLE baseline visit, eligible patients may receive open-label dapagliflozin for at least 12 weeks but up to 24 additional weeks, or through the end of the open-label extension period, whichever is shortest. Approximately 60 patients from the open-label extension period will be enrolled into the OLE Sub study.