The purpose of this study is to determine if zigakibart is safe and effective for long-term use in patients with immunoglobulin A nephropathy (IgAN). This is an extension study for patients who have already completed an another zigakibart study.

This is an open-label Phase 2 study evaluating the long term safety and tolerability of GFB-887 in patients with focal segmental glomerulosclerosis (FSGS), and treatment-resistant minimal change disease (TR-MCD)