C3 and primary membranoproliferative glomerulonephritis: However, recent advances in targeted complement inhibitor therapy have been made in these diseases with positive results from phase 3 clinical trials of both the factor B inhibitor, iptacopan (in adults with native kidney C3G) and the C3/C3b inhibitor, pegcetacoplan (in adults and adolescents with native or posttransplant C3G or primary IC-MPGN).