Randomized, Double-Blind, Safety and Efficacy Study of RE-021 (Sparsentan) in Focal Segmental Glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a rare glomerular disorder which results in frank proteinuria and in some patients progression to end-stage kidney disease (ESKD) over 5-10 years. Proteinuria reduction is widely regarded to be beneficial and is considered the primary goal of treatment in FSGS and slowing its progressive course (D'Agati, et. al, 2011). Patients are currently treated with angiotensin receptor blockers (ARB) and angiotensin converting inhibitors (ACEI) to lower proteinuria with steroids, calcineurin inhibitors, and other immunosuppressive agents reserved for patients with severe proteinuria and in particular with nephrotic syndrome. Despite these therapies, many patients have nephrotic range proteinuria and new therapeutic agents are needed. Endothelin receptor antagonists (ERA) have been shown to lower proteinuria in clinical trials of diabetic nephropathy and have been speculated to be effective in FSGS.