Normalisation of haemoglobin and control of breakthrough haemolysis with increased frequency pegcetacoplan dosing in treated paroxysmal nocturnal haemoglobinuria.

Paroxysmal nocturnal haemoglobinura is an acquired life-threatening haemolytic condition, which is generally well controlled with terminal complement blockade with eculizumab. Whilst almost all patients treated with terminal complement inhibitors develop extravascular haemolysis, only a small proportion of these results in symptomatic anaemia limiting their activities and requiring red cell transfusion. This case highlights the potential role for the C3 inhibitor, pegcetacoplan, in controlling both intravascular and extravascular haemolysis, and is the first case to report on the use of additional doses of pegcetacoplan to control breakthrough haemolysis.