CD40LG and systemic lupus erythematosus: Although the CD40–CD40 ligand (CD40L) signaling axis is important for the abnormal development and maturation of T cells and B cells in SLE patients, many trials of anti‐CD40 antibodies, such as rupizumab (BG9588), ibanalumab (VAY736), and iscalimab (CFZ533) [264], have terminated or failed to meet primary endpoints [265, 266] because of adverse effects (AEs) or unsatisfactory therapeutic outcomes in SLE patients.