C5 and paroxysmal nocturnal hemoglobinuria: Ravulizumab (ALXN1210), a second generation anti-C5 mAb engineered from eculizumab, has recently received marketing authorization for the treatment of adult patients with PNH in the United States, EU, and Japan, based on the positive results of the two published Phase 3 ALXN1210-301 and 302 clinical trials demonstrating an equal efficacy and a similar safety profile to the current standard of care treatment with eculizumab [11–13].