C3 and paroxysmal nocturnal hemoglobinuria: To date, only four anti‐complement therapies have been approved: C5 inhibition with eculizumab, of great benefit in PNH and aHUS, more recently approved for the treatment of myasthenia gravis (MG) and neuromyelitis optica (the eculizumab follow‐up antibody, ravulizumab, with a prolonged half‐life, has also been approved for the treatment of PNH, aHUS, and MG); avacopan, a specific inhibitor of C5a approved for the treatment of ANCA vasculitis98; pegcetacoplan, an inhibitor of C3 activation in PNH; and sutimlimab (a C1s inhibitor) in cold agglutinin disease.