Genetic variants in C5 and poor response to eculizumab.

Background: Eculizumab is a humanized monoclonal antibody that targets complement protein C5 and inhibits terminal complement-mediated hemolysis associated with paroxysmal nocturnal hemoglobinuria (PNH). The molecular basis for the poor response to eculizumab in a small population of Japanese patients is unclear.

Methods: We assessed the sequences of the gene encoding C5 in patients with PNH who had either a good or poor response to eculizumab.