This is a multicenter, open-label, 112-week study of sparsentan in approximately 57 pediatric subjects aged ≥1 year to <18 years with selected proteinuric glomerular diseases, divided into 2 populations, defined as follows:~Population 1: Subjects with selected proteinuric glomerular diseases associated with Focal Segmental Glomerulosclerosis (FSGS) and Minimal Change Disease (MCD) histological patterns~Population 2: Subjects with kidney biopsy-confirmed immunoglobulin A nephropathy (IgAN), immunoglobulin A vasculitis (IgAV), or subjects with Alport syndrome (AS)~The study will evaluate long-term safety, tolerability, and efficacy with pharmacokinetic evaluations at Day 1 (Baseline), Day 2 (Visit 4), and Week 12 (Visit 9). For each population, subjects will be enrolled in 3 cohorts based on age ranges.~Study Enrollment:~Population 1: FSGS and/or MCD (30 subjects total)~Cohort 1 (6 subjects): ≥8 years to <18 years~Cohort 2 (18 subjects): ≥3 years to <8 years~Cohort 3 (6 subjects): ≥1 year to <3 years~Population 2: IgAN, IgAV, or AS (27 subjects total)~Cohort 1 (9 subjects): ≥8 years to <18 years~Cohort 2 (12 subjects): ≥5 years to <8 years~Cohort 3 (6 subjects): ≥2 years to <5 years
To evaluate the safety, efficacy and tolerability of sparsentan oral suspension and assess changes in proteinuria after once-daily dosing over the 108-week treatment period.