C5 and paroxysmal nocturnal hemoglobinuria: For example, the annual cost of Eculizumab treatment of a PNH patient is £340 000 in the UK, and the antibody must be administered bi‐weekly by intravenous infusion (900 mg/dose).4 There are many agents in development that target C5, for example, SKY59 (RO7112689) an anti‐C5 mAb now in phase II clinical trials.