Drugs in phase 2 trials for lupus nephritis include ravulizumab, an anti-C5 monoclonal antibody; iptacopan, a complement factor B inhibitor; vemircopan, a complement factor D inhibitor; narsoplimab, an anti-MBL-associated serine protease 2 monoclonal antibody; and pegcetacoplan, a PEGylated C3 inhibitor. Here, C3 is linked to lupus nephritis.