 Eculizumab was approved by the US Food and Drug Administration (FDA) in March 2007 for the treatment of PNH, Eculizumab has exclusivity rights until 2017, which protects it from competition until 2017.When the FDA approved it in September 2011 for the treatment of aHUS, it designated it as an orphan drug.The 2011 FDA approval was based on two small prospective trials of 17 people and 20 people.