(Adds details on treatment, sales estimates, background)
Dec 21 (Reuters) - The U.S. Food and Drug Administration on Friday approved Alexion Pharmaceuticals Inc's rare blood disorder drug Ultomiris, nearly two months earlier than expected.
The drug's sales are expected to reach $1.66 billion by 2022, according to IBES data from Refinitiv.
Ultomiris was approved to treat patients with paroxysmal nocturnal hemoglobinuria (PNH), a rare, acquired, life-threatening disorder in which red blood cells are prematurely destroyed.
Alexion already markets treatments for rare diseases, and its drug Soliris is approved to treat PNH.
The FDA had set Feb. 18 as the date for a decision.
Reporting by Manas Mishra in Bengaluru; Editing by Sriraj Kalluvila