Study of the Safety and Efficacy of OMS721 in Patients With Immunoglobulin A (IgA) Nephropathy

This is a Phase 3, double-blind, randomized, placebo-controlled, study in patients aged 18 years and above with a biopsy-confirmed diagnosis of IgAN and with 24-hour UPE that is \> 1 g/day. The purpose of this study is to evaluate the efficacy and safety of narsoplimab (OMS721) compared to placebo on proteinuria and whether narsoplimab has the ability to slow disease progression in primary IgAN patients. The primary objective of the study is to evaluate proteinuria reduction as assessed by 24-hour UPE at 36 weeks from baseline. The trial will continue beyond 36 weeks in a blinded fashion to provide confirmatory evidence of long-term efficacy based on the annualized slope of eGFR over 24 months. The trial will enroll approximately 450 patients with 225 patients per arm, all having biopsy-proven IgAN with eGFR≥30 mL/min/1.73m\^2 and 24 hour UPE \>1g/day. The study duration for each patient is expected to last approximately 112 weeks.